Spatio-temporal distributions of δ18O, δD and salinity in the Arabian Sea: Identifying processes and controls

Marine Chemistry 157 (2013) 144–161

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Spatio-temporal distributions of δ18O, δD and salinity in the Arabian Sea: Identifying processes and controls R.D. Deshpande a,⁎, P.M. Muraleedharan b, Raj Laxmi Singh a, Bhishm Kumar c,1, M. Someshwar Rao c, Medha Dave a, K.U. Sivakumar b, S.K. Gupta a a b c

Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, India National Institute of Oceanography, Dona Paula, Goa 403 004, India National Institute of Hydrology, Roorkee, Uttarakhand 247 667, India

a r t i c l e

i n f o

Article history: Received 12 June 2013 Received in revised form 1 October 2013 Accepted 2 October 2013 Available online 9 October 2013 Keywords: Arabian Sea Stable isotopes Salinity Summer monsoon India

a b s t r a c t Isotopic compositions (δ18O and δD) and salinity (S) of 683 surface water samples from the Arabian Sea (AS) collected during 2008–2010, were measured to understand the factors controlling the spatio-temporal distribution of these parameters. From the distributions of δ18O and salinity (S), and the relationships between δ18O–δD and δ18O–S, the following inferences have been drawn: (1) there is a broad correspondence between the geographic distributions of the δ18O and S; (2) in spite of a large scatter, a statistically significant δ18O–S relationship can be identified in much of the investigated part of the AS; (3) the δ18O–δD regression line for all samples clumped together has a slope of 3.2 (±0.16), much lower than that (7.37) for the global ocean surface water line (GOSWL), which in the case of the AS is seen only for samples with salinity b34; (4) the linear relationship between δ18O and δD breaks down completely in the months of March–May; (5) contrary to the adjoining Bay of Bengal (BOB), both δ18O and S progressively increase from the equator northwards; (6) the δ18O–δD and the δ18O–d-excess relationships indicate strong kinetic fractionation due to evaporation from surface waters of the AS throughout the year, with enhancement during summer months. © 2013 Elsevier B.V. All rights reserved.

1. Introduction The Arabian Sea (AS) is located in the northwestern region of the Indian Ocean. The largest rivers emptying into the AS are the Indus, Narmada, Mahi, Tapti, and numerous small rivers from the west coast of India and the Arabian Peninsula (http://www.nih.ernet.in/rbis/ india_information/rivers.htm). The surface area of the AS is ~3.95 × 106 km2. The highest salinity is found in the northern part of the basin as a result of high evaporation rates and input of salty water from the Persian Gulf and the Red Sea (Prasanna Kumar and Prasad, 1999; Prasanna Kumar et al., 2001). The northern AS receives little precipitation. In contrast, eastern part of the AS receives heavy precipitation (~300–400 cm a−1; http://www. imd.gov.in/section/climate/climate-rain.htm) all along the west coast of India during the summer southwest monsoon. Precipitation on the west coast of India systematically increases from Mumbai (~19°N), to Thiruvananthapuram (~8.5°N) by ~350 mm/° latitude (Sarkar et al., 2000). The spatio-temporal variation in the formation, movement and mixing of different water masses within the AS is governed by a combination of several processes, namely, evaporation, continental runoff, ⁎ Corresponding author. E-mail address: [email protected] (R.D. Deshpande). 1 Presently at: International Atomic Energy Agency, A-1400 Vienna, Austria. 0304-4203/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.marchem.2013.10.001

direct precipitation over the sea surface, and the ocean currents governed by the seasonal reversal of winds. In addition, at deeper levels, spreading of water from the adjoining Persian Gulf and the Red Sea, respectively via Gulf of Oman and Gulf of Aden, is also an important feature affecting the dynamics of water masses (Rochford, 1964; Prasanna Kumar and Prasad, 1999) in the AS (Fig. 1). Improved understanding of these processes is important due to their bearing on other significant issues, namely, vapor source variation for monsoon precipitation over India (Breitenbach et al., 2010), variability in tropical cyclonogenesis (Evan and Camargo, 2011; Evan et al., 2011), upper ocean response to monsoonal forcing (Lee et al., 2000), past monsoon variability, formation and spread of high salinity water mass (Prasanna Kumar and Prasad, 1999), primary productivity and marine biogeochemical processes (Gauns et al., 2005). The dynamics of water in an oceanic water body also governs its surface water temperature, which in turn can affect evaporation, atmospheric vapor loading, convection and precipitation (Das, 2005; Shenoi et al., 2002). Thus, surface water dynamics, through surface temperature variation, is coupled with the atmospheric water vapor budget of the AS, which is known to have strongly positive net divergence flux (E-P) of about 1m/yr (~3mm/day), which peaks during summer months (JJA) to as high as 20 mm/day (Delaygue et al., 2001; Trenberth and Guillemot, 1998). During the summer monsoon season a large volume (0.4 sV i.e. 4 × 105 m3 s−1) of moisture is transported from the AS to the Indian continent (Hastenrath and Greischar, 1993) and contributes

R.D. Deshpande et al. / Marine Chemistry 157 (2013) 144–161

Fig. 1. Schematic representation of the circulation in the Indian Ocean during (a) January (winter monsoon) and (b) July (summer monsoon). Redrawn from Shankar et al. (2002). The abbreviations are as follows: SC, Somali Current; EC, Equatorial Current; SMC, Summer Monsoon Current; WMC, Winter Monsoon Current; EICC, East India Coastal Current; WICC, West India Coastal Current; SECC, South Equatorial Counter Current, EACC, East African Coastal Current; SEC, South Equatorial Current; LH, Lakshadweep high; and LL, Lakshadweep low.

to precipitation. Cadet and Reverdin (1981) estimated the AS contribution to the monsoonal precipitation over India to be about 20%, the remainder originating from the Southern Hemisphere. However, considerable regional variability in contribution may be expected due to complex interactions involving surface temperature contrast between the AS coast off Somali (~15 °C) and off Mumbai (25°–30 °C) and resultant impact on monsoon winds (Das, 2005; Izumo et al., 2008); and location and regional extent of warm pools (Izumo et al., 2008; Sijikumar and Rajeev, 2012). The seasonal reversal of winds and the associated forced reversing of circulation in the upper ocean, twice a year, also affects the surface dynamics of the AS. A schematic representation of the winter (Fig. 1a) and summer (Fig. 1b) circulation in the Indian Ocean is redrawn based on Shankar et al. (2002). Different parts of the ocean currents, as shown in Fig. 1, form at different times, and only in their mature phase these currents exist as trans-basin flows (Shankar et al., 2002). In the context of the AS, circulation in summer (SW monsoon) is typical of an eastern boundary – an equator ward flowing West India Coastal Current (WICC), a pole-ward undercurrent and coastal upwelling. The eastward flowing Summer Monsoon Current (SMC) is a continuation of the Somali Current and the coastal current off Oman. It flows eastward and southeastward across the AS and around the Lakshadweep low, eastward south of Sri Lanka, and into the Bay of Bengal (BOB). The mature phase of the SMC lasts from May to September. In contrast, the westward flowing Winter Monsoon Current (WMC) divides into two branches. One of these branches continues flowing westwards, whereas the other turns around the Lakshadweep high to flow pole-

145

ward as WICC causing down-welling. In addition to the various ocean currents as above, Rochford (1964) identified three distinct water masses that originate in the northern AS, namely, the Arabian Sea High Salinity Water (ASHSW) mass, the Persian Gulf Water (PGW) mass and the Red Sea Water (RSW) mass. Of these, ASHSW is the shallowest and its core moves seasonally between 25° and 10°N (Prasanna Kumar and Prasad, 1999). The dynamics of water masses in oceanic water bodies are often studied through their δ18O–S relationships. The isotopic composition of water is usually expressed in δ notation in terms of per mil (‰) with reference to an international standard [δ18O or δD = (Rsample/ Rstandard – 1) × 1000], where R denotes the abundance ratio of heavy to light isotope [i.e., 18O/16O or 2H (or D)/1H] in the sample or standard. In the case of water, the international standard refers to ViennaStandard Mean Ocean Water (V-SMOW). The salinity usually refers to Practical Salinity (S) defined in terms of the ratio of the electrical conductivity of a seawater sample at the temperature of 15 °C and the pressure of one standard atmosphere, to that of a KCl solution, in which the mass fraction is 32.4356 × 10−3, at the same temperature and pressure. This ratio equal to 1 corresponds, by definition, to a Practical Salinity exactly equal to 35 (Millero, 2011; Millero et al., 2008; UNESCO, 1981a, 1981b). The δ18O–S relationship is an important parameter to characterize and differentiate between different oceanic waters and even to identify the contribution from different water masses/processes (runoff, precipitation, upwelling, evaporation) to a given oceanic water body. The usefulness of δ18O–S relationship arises from the fact that the two parameters are expected to have a spatially linear relationship because they respond similarly to evaporation and dilution. Besides this, the mixing due to oceanic advection and dispersion is expected to modify the δ18O–S relationship in a predictable manner (Broecker, 1990; Craig and Gordon, 1965; Delaygue et al., 2001; Östlund and Hut, 1984; Pierre et al., 1994). In addition, δ18O–S relationship is also an important parameter in paleo-oceanographic studies (Delaygue, 2001; Broecker, 1990; Duplessy, 1981, 1982; Rostek et al., 1993). The isotope and salinity data can also be useful to constrain various models of water mass movement (Delaygue, 2001). In spite of this, the existing understanding about the δ18O–S relationship in the AS is based only on a limited number of data pairs (Delaygue et al., 2001; Singh et al., 2010). The observed δ18O–S relationship (δ18O = 0.26 × S − 8.9) by Delaygue (2001) is based on seawater samples, most of which are from near the Gulf of Aden in the western AS. Recently, Singh et al. (2010) have compiled the δ18O–S relationships for different seasons in the AS. However, these relationships have certain limitations; namely, (i) samples are restricted to the southeastern or northeastern AS; (ii) number of samples is limited; and (iii) in some cases the δ18O–S relationship is derived from proxies in the sediments (Rostek et al., 1993) rather than direct measurement of oceanic water. In addition to δ18O–S relationship, the deuterium excess (d-excess= δD − 8 × δ18O) is also an important derived parameter (Dansgaard, 1964) which is strongly dependent on the kinetic fractionation of isotopes associated with evaporation of seawater and can aid identification of water masses originating from different parts of the ocean. While δ18O and S have been monitored in most oceanographic studies, there are only a few studies, in which both δ18O and δD have been measured, particularly from the AS (Srivastava et al., 2010; Rohling, 2007). This is perhaps because of a generally held view that the two isotopes in oceanic surface waters are expected to be homogeneous as in precipitation for which the relationship between the two is linear. However, as discussed earlier, the hydrology of the AS is quite complex due to variable precipitation and evaporation (both spatially and temporally), temperature contrast between the west and the east coast of the AS, monsoon driven seasonal reversal of circulation, and transfer of water masses between the BOB and the AS, between the northwestern parts (Gulfs) and the eastern part of the AS and from the southern Indian Ocean. As a result, δ18O, δD and salinity relationships in the AS may exhibit a spatio-

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temporally variable behavior. Therefore, an important objective of this study was to identify impacts of various involved processes on surface water dynamics and the distribution of natural tracers such as δ18O, δD and salinity from closely spaced sampling with much wider spatial representation of the AS. 2. Methodology The AS surface water samples (N = 683; depth ≤2 m), investigated in this study, were collected during the years 2008–2010 using different cruises as given in Table 1. All the sample bottles were checked for their air-tightness and were stored in the air-conditioned sample repository maintained at 24 ± 2 °C temperature. The geographical distribution of all sample locations is shown in Fig. 2. The samples were collected from the bow side of the vessel and were transferred into clean and dry sampling bottles from the bucket sampler. The cruises for sampling were chosen to address distribution of salinity and isotope from (i) near the west coast of India; (ii) open ocean of the eastern AS; and (iii) profiles across 0° to about 10°N latitude along ~65° and ~75°E longitude during different seasons. The samples were analyzed onboard, for salinity, using salinometers (Digi Autosal; The Tsurumi-Seiki Co., Japan or Autosal: Guildline 8400B, Canada). The isotopic analyses of water samples (δ18O and δD) were carried out at two laboratories, namely, the National Institute of Hydrology (NIH), Roorkee, India and the Physical Research Laboratory (PRL), Ahmedabad, India, following standard equilibration method in which water samples were equilibrated with CO2 (or H2) and the equilibrated CO2 (or H2) gas was analyzed in Isotope Ratio Mass Spectrometer (IRMS). At NIH, the δ18O and δD analyses were made using Isoprime IRMS in Dual Inlet mode (Kumar et al., 2010). At PRL, these analyses were made using Delta V Plus IRMS coupled to a Gasbench II in continuous flow mode (Maurya et al., 2009). The external reproducibility of measurements, based on analyses of multiple aliquots of the secondary laboratory standards, was better than 0.1‰ for δ18O and 1‰ for δD with respect to VSMOW at both the laboratories. The secondary laboratory standards, of which multiple aliquots are used in each batch of samples, were calibrated with international standard reference materials for water (VSMOW, SLAP, GISP). Inter-laboratory calibration including Isotope Hydrology Laboratory at IAEA, Vienna indicated that analyses from all the three laboratories were in agreement within ±0.1‰ for δ18O and 1‰ for δD. 3. Results and discussion 3.1. Spatial distribution The measured values of δ18O, δD and Salinity (S) along with geographical coordinates of sample locations are given in Table 1, which also identifies the analyzing laboratory. The contour plots of δ18O and S (Fig. 3) indicate a very narrow range of variation of both the parameters over much of the AS except very close to the west coast of India. The area weighted averages are 0.9 ± 0.3‰ for δ18O (range: –0.56 to 1.95) and 35.4 ± 0.9 for S (range: 28.9 to 37.2). The distributions (Fig. 3) of these parameters exhibit broad geographical correspondence with each other but the δ18O–S plot (Fig. 4a), shows considerable scatter. In spite of this scatter, the regression line [δ18O = (0.14 ± 0.01) × S – (4.31 ± 0.33); R2 = 0.25; p b 0.001; Fig. 4a] for all samples (N = 682) is statistically significant, using F statistics available in the ANOVA (analyses of variance) tool in the MS Excel. The value of significance of F (i.e. p) in the ANOVA examines if the observed regression output could have been obtained by chance or not. The low value of p (b 0.001) indicates that there is negligible (0.1%) possibility that the observed correlation could have been there by chance. The δ18O–S plot seems to also separate the surface waters of the AS into two groups, namely Group A (largely open ocean samples) and Group B (largely coastal samples). The samples in Group B (S b34) have relatively less scatter and narrower

range of δ18O compared to samples in Group A. If the Group A samples are excluded in the δ18O–S regression, the line slope (=0.08) decreases marginally and there is only a small improvement in the R2 (=0.28) value indicating that the regression line for the complete set of samples may reasonably represent the entire Arabian Sea, as a two component mixing, namely, high salinity open seawater with low salinity runoff from the west coast of India, with local variations in evaporation/ precipitation causing the observed scatter. The plot of d-excess versus S (Fig. 4b) also shows a considerable scatter with a large range in d-excess for samples with salinity N34 (Group A). For coastal samples (Group B), the d-excess values are relatively higher (average: 1 ± 1‰) indicating a mixture of continental runoff (d-excess ~10‰) and ocean water (d-excess ~0‰). This is also indicated by relatively lower values of both salinity (b34) and δ18O (b0.5‰) for these samples. Samples with salinity N34 are located away from the west coast of India where dilution from fresh water plays a small role in determining the covariation of the isotopic parameters with the salinity. For this group (Group A), the covariation of parameters is additionally governed by the direct precipitation, evaporation and mixing due to ocean currents. Obviously, the two groups have some overlap as seen in Fig. 4 suggesting that boundary values of salinity (34) and δ18O (0.5‰) are only approximate. The strip of water with significant admixture of continental runoff indicated by these low values of salinity and δ18O (Group B) is very narrow (across 1°–2° longitude) as can be seen from the contour plots of Fig. 3. This is in spite of the fact that very heavy precipitation (200– 800 cm) occurs on the Western Ghats, which largely runs off the steep slopes into the eastern AS, suggesting limited lateral dispersion. Table 2 gives the amount weighted average δ18O of rainfall at a few selected stations along the west coast of India. From this table, the amount weighted average δ18O for the runoff from the west coast of India is estimated to be –2.7‰. Using this value as one end member and the area weighted average δ18O value of the AS (0.9‰) as the other end member, one can estimate that the surface coastal waters (salinity b 34 and δ18O b0.5‰) contain about 12% of runoff. The observed high values of δ18O and salinity north of 18°N (Fig. 3) may be ascribed to high evaporation, considering that similar high values are also observed between 3° to 12°N and 68° to 70°E where evaporation alone (indicated by very low d-excess values) can explain such high values of δ18O and salinity, though the present study does not cover much of the intervening region and d-excess values from this region have not been measured. The δ18O–δD regression [δD = (3.2 ± 0.2) × δ18O + (3.1 ± 0.1); R2 = 0.55; pb0.001] of all the AS surface water samples (N=335) considered together is statistically significant. This regression slope is much lower than the GOSWL (δD = 7.37 × δ18O − 0.72; R2 = 0.97; N = 244; Rohling, 2007). As with salinity and isotope plots (Fig. 4), the δ18O–δD scatter plot (Fig. 5a) can also be split into two regression lines representing two different water masses, namely Group A [δD = (1.8 ± 0.2) × δ18O + (4.5 ± 0.2); R2 = 0.2; p b 0.001; N = 237] and Group B [δD = (7.3 ± 0.6) × δ18O + (1.7 ± 0.2); R2 = 0.6; p b 0.001; N = 98]. The slope of regression line for Group B samples is comparable to the GOSWL (Rohling, 2007). The slightly higher value of intercept for samples of Group B, compared to GOSWL, is an indication that the samples with values of salinity b34 and δ18O b0.5‰ represent an admixture of continental runoff (d-excess ~10‰) and samples of Group A (average d-excess: −1.3 ± 2‰). This is also evident from the d-excess values (average: 1 ± 1‰) of Group B samples, which is intermediate between these two values. The δ18O–δD regression for Group A samples (i.e. with salinity N 34 and δ18O N0.5‰) has a significantly lower slope (1.8) and a large scatter corroborating significant evaporation and/or mixing of high salinity waters of different origin. Similar grouping with some overlap as in Fig. 4 is also seen in the plot of d-excess against δ18O (Fig. 5b). The progressive decrease in d-excess with increasing δ18O in Fig. 5b for samples comprising Group A is also an indication that much of the AS surface

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Table 1 Arabian Sea surface water samples. Details concerning sample collection, salinity and isotopic measurements. Sr no

Sample code

Collection date

Cruise code

Long °E

Lat °N

Salinity instrument

Salinity

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73

UMC-3734 UMC-3735 UMC-3736 UMC-3696 UMC-3697 UMC-3698 UMC-3699 UMC-3700 UMC-3701 UMC-3702 UMC-3688 UMC-3689 UMC-3690 UMC-3691 UMC-3692 UMC-3693 UMC-3703 UMC-3680 UMC-3694 UMC-3695 UMC-3681 UMC-3682 UMC-3683 UMC-3684 UMC-3685 UMC-3686 UMC-3687 UMC-3672 UMC-3673 UMC-3674 UMC-3675 UMC-3634 UMC-3635 UMC-3676 UMC-3677 UMC-3678 UMC-3679 UMC-3636 UMC-3671 UMC-3637 UMC-3638 UMC-3639 UMC-3640 UMC-3641 UMC-3626 UMC-3627 UMC-3774 UMC-3775 UMC-3628 UMC-3629 UMC-3776 UMC-3630 UMC-3632 UMC-3633 UMC-3777 UMC-3622 UMC-3623 UMC-3778 UMC-3779 UMC-3780 UMC-3781 UMC-3624 UMC-3625 UMC-3766 UMC-3767 UMC-3768 UMC-3769 UMC-3770 UMC-3771 UMC-3772 UMC-3773 UMC-3760 UMC-3761

24-Aug-08 25-Aug-08 28-Aug-08 23-Sep-08 23-Sep-08 23-Sep-08 23-Sep-08 23-Sep-08 23-Sep-08 23-Sep-08 24-Sep-08 24-Sep-08 24-Sep-08 24-Sep-08 24-Sep-08 24-Sep-08 24-Sep-08 25-Sep-08 25-Sep-08 25-Sep-08 26-Sep-08 26-Sep-08 27-Sep-08 28-Sep-08 28-Sep-08 29-Sep-08 30-Sep-08 1-Oct-08 2-Oct-08 3-Oct-08 3-Oct-08 4-Oct-08 4-Oct-08 4-Oct-08 4-Oct-08 4-Oct-08 4-Oct-08 5-Oct-08 5-Oct-08 6-Oct-08 6-Oct-08 7-Oct-08 8-Oct-08 8-Oct-08 11-Oct-08 11-Oct-08 11-Oct-08 11-Oct-08 12-Oct-08 12-Oct-08 12-Oct-08 13-Oct-08 14-Oct-08 14-Oct-08 14-Oct-08 15-Oct-08 15-Oct-08 15-Oct-08 15-Oct-08 15-Oct-08 15-Oct-08 16-Oct-08 16-Oct-08 16-Oct-08 16-Oct-08 16-Oct-08 16-Oct-08 17-Oct-08 17-Oct-08 17-Oct-08 17-Oct-08 18-Oct-08 18-Oct-08

SSM-275-A SSM-275-A SSM-275-A SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SK-250 SSM-258 SSM-258 SK-250 SK-250 SK-250 SK-250 SSM-258 SK-250 SSM-258 SSM-258 SSM-258 SSM-258 SSM-258 SSM-258 SSM-258 ABP ABP SSM-258 SSM-258 ABP SSM-258 SSM-258 SSM-258 ABP SSM-258 SSM-258 ABP ABP ABP ABP SSM-258 SSM-258 ABP ABP ABP ABP ABP ABP ABP ABP ABP ABP

75.60 75.58 75.15 73.63 73.65 73.63 73.63 73.64 73.65 73.61 73.50 73.63 73.77 73.87 73.93 73.99 73.51 74.06 74.00 74.00 74.10 74.15 74.26 74.30 74.36 74.46 74.56 74.71 74.81 74.86 75.07 73.01 71.97 76.67 77.09 77.53 78.31 72.88 79.86 73.46 75.29 74.01 74.04 74.51 74.43 74.94 72.47 72.88 74.82 75.27 72.53 75.60 75.96 76.29 72.48 76.40 76.77 72.58 72.68 73.08 73.37 77.49 77.51 73.52 73.93 74.20 74.48 75.15 76.15 76.35 77.10 77.72 78.40

9.96 9.99 10.00 14.72 13.90 13.51 13.11 12.67 12.27 11.84 11.05 10.64 10.26 9.87 9.50 9.09 11.44 7.77 8.60 7.83 7.74 9.00 8.25 7.74 8.35 8.35 8.75 8.67 8.88 8.06 7.72 17.01 17.01 7.05 6.89 6.72 6.40 15.50 5.77 15.50 14.19 14.20 12.85 12.27 12.00 12.00 15.42 16.38 11.37 11.36 18.07 9.95 9.01 9.01 18.02 8.48 8.47 17.02 15.93 15.03 14.05 7.24 7.81 13.12 12.02 11.02 10.00 8.98 7.02 7.17 6.03 5.07 4.02

Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi Digi

34.60 34.05 34.00 33.69 35.29 35.29 35.17 34.75 35.05 34.99 35.41 35.00 34.86 34.61 34.89 35.16 34.58 35.08 35.08 34.92 35.10 34.96 34.84 35.17 34.91 35.11 35.36 35.32 35.43 35.40 35.21 35.28 35.58 35.30 34.80 34.99 35.03 33.87 35.28 33.44 35.37 33.40 34.99 33.93 34.99 34.65 35.82 36.17 34.34 34.11 36.14 34.43 35.16 35.01 36.38 35.31 35.23 36.71 36.71 37.00 36.50 29.50 35.13 36.14 36.28 37.09 37.15 36.58 37.18 37.10 36.87 36.95 37.05

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Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal

δ18O (‰) 0.73 0.60 0.61 0.42 0.81 0.68 0.63 0.47 0.92 0.83 0.68 0.68 0.75 0.89 0.57 0.83 0.91 0.96 0.86 0.90 0.94 0.58 0.84 0.61 0.81 0.75 0.96 0.64 0.84 0.54 0.45 1.03 0.96 0.88 0.37 0.56 0.36 0.56 0.83 0.63 0.81 0.47 0.72 0.57 0.98 0.52 0.44 0.71 0.73 1.45 0.51 0.65 1.39 1.20 0.70 0.67 1.57 0.88 0.49 0.94 0.99 0.74 0.57 0.68 0.99 1.12 0.69 0.72 0.64 0.64 0.50 0.72 0.71

δD (‰)

d-excess (‰)

Identified group

Analyzing laboratory

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

A A A/B B A A A A/B A A A A A A A A A A A A A A A A A A A A A A A/B A A A A/B A A/B A/B A A/B A B A A/B A A A/B A A A A A A A A A A A A/B A A A/B A A A A A A A A A A A

PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL

(continued on next page)

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R.D. Deshpande et al. / Marine Chemistry 157 (2013) 144–161

Table 1 (continued) Sr no

Sample code

Collection date

Cruise code

Long °E

Lat °N

Salinity instrument

Salinity

74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149

UMC-3762 UMC-3763 UMC-3764 UMC-3765 UMC-3742 UMC-3743 UMC-3744 UMC-3745 UMC-3746 UMC-3747 UMC-3737 UMC-3738 UMC3739 UMC-3740 UMC-3741 UMC-3748 UMC-3749 UMC-3663 UMC-3664 UMC-3665 UMC-3666 UMC-3667 UMC-3668 UMC-3669 UMC-3783 UMC-3784 UMC-3655 UMC-3656 UMC-3657 UMC-3658 UMC-3670 UMC-3785 UMC-3786 UMC-3652 UMC-3653 UMC-3659 UMC-3660 UMC-3661 UMC-3662 UMC-3787 UMC-3807 UMC-3654 UMC-3788 UMC-3789 UMC-3790 UMC-3808 UMC-3809 UMC-3810 UMC-3726 UMC-3727 UMC-3782 UMC-3811 UMC-3728 UMC-3729 UMC-3812 UMC-3813 UMC-3814 UMC-3730 UMC-3731 UMC-3802 UMC-3803 UMC-3804 UMC-3732 UMC-3805 UMC-3806 UMC-3718 UMC-3733 UMC-3719 UMC-3720 UMC-3721 UMC-3722 UMC-3723 UMC-3724 UMC-3725 UMC-3714 UMC-3715

18-Oct-08 18-Oct-08 19-Oct-08 19-Oct-08 14-Nov-08 14-Nov-08 14-Nov-08 14-Nov-08 14-Nov-08 14-Nov-08 15-Nov-08 15-Nov-08 15-Nov-08 15-Nov-08 15-Nov-08 15-Nov-08 15-Nov-08 02-Dec-08 02-Dec-08 03-Dec-08 03-Dec-08 03-Dec-08 03-Dec-08 03-Dec-08 4-Dec-08 4-Dec-08 04-Dec-08 04-Dec-08 04-Dec-08 04-Dec-08 04-Dec-08 5-Dec-08 5-Dec-08 05-Dec-08 05-Dec-08 05-Dec-08 05-Dec-08 05-Dec-08 05-Dec-08 6-Dec-08 6-Dec-08 06-Dec-08 7-Dec-08 7-Dec-08 7-Dec-08 7-Dec-08 7-Dec-08 7-Dec-08 07-Dec-08 07-Dec-08 8-Dec-08 8-Dec-08 08-Dec-08 08-Dec-08 9-Dec-08 9-Dec-08 9-Dec-08 09-Dec-08 09-Dec-08 10-Dec-08 10-Dec-08 10-Dec-08 10-Dec-08 11-Dec-08 11-Dec-08 11-Dec-08 11-Dec-08 12-Dec-08 12-Dec-08 13-Dec-08 17-Dec-08 17-Dec-08 18-Dec-08 18-Dec-08 19-Dec-08 20-Dec-08

ABP ABP ABP ABP SSK-181 SSK-181 SSK-181 SSK-181 SSK-181 SSK-181 SSK-181 SSK-181 SSK-181 SSK-181 SSK-181 SSK-181 SSK-181 SM-8 SM-8 SM-8 SM-8 SM-8 SM-8 SM-8 MVK-124 MVK-124 SM-8 SM-8 SM-8 SM-8 SM-8 MVK-124 MVK-124 SM-8 SM-8 SM-8 SM-8 SM-8 SM-8 MVK-124 SK-252 SM-8 MVK-124 MVK-124 MVK-124 SK-252 SK-252 SK-252 SP-12/08 SP-12/08 MVK-124 SK-252 SP-12/08 SP-12/08 SK-252 SK-252 SK-252 SP-12/08 SP-12/08 SK-252 SK-252 SK-252 SP-12/08 SK-252 SK-252 SP-12/08 SP-12/08 SP-12/08 SP-12/08 SP-12/08 SP-12/08 SP-12/08 SP-12/08 SP-12/08 SP-12/08 SP-12/08

79.45 79.95 80.63 81.43 71.65 71.60 71.65 71.60 71.60 71.65 71.13 71.13 71.10 71.13 71.10 71.10 71.10 73.84 74.08 74.73 75.00 75.11 75.19 75.28 75.50 74.50 75.43 75.52 75.78 75.63 75.53 73.50 72.73 73.51 73.49 74.80 74.26 74.00 73.75 73.63 65.00 73.26 73.28 73.08 74.00 65.00 65.00 65.00 73.21 73.48 75.00 65.00 74.28 73.55 65.00 65.00 65.00 74.47 74.09 65.00 65.00 65.35 74.50 66.81 67.66 75.08 75.47 75.89 75.29 75.95 76.29 75.85 75.94 75.32 74.77 74.15

2.80 2.02 1.13 0.00 19.28 19.28 19.35 19.35 19.43 19.43 19.47 19.50 19.62 19.63 19.67 19.43 19.47 15.00 14.32 12.62 11.93 11.25 10.52 9.89 10.03 10.23 9.05 9.39 10.32 10.87 9.00 10.40 10.55 13.67 13.77 12.24 12.86 13.30 14.55 9.98 1.00 15.15 9.00 8.37 8.77 2.00 3.00 4.00 14.54 14.33 9.33 5.00 14.22 14.13 6.00 7.00 8.00 13.63 13.39 9.00 10.00 10.15 12.70 11.17 11.69 11.70 11.82 11.33 10.99 9.68 9.93 9.85 10.81 11.03 12.88 15.03

Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Digi Auto Digi Auto Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Digi Auto Digi Auto Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Digi Auto Digi Auto Auto Sal Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Auto Sal Auto Sal Digi Auto Digi Auto Auto Sal Auto Sal Digi Auto Digi Auto Digi Auto Auto Sal Auto Sal Digi Auto Digi Auto Digi Auto Auto Sal Digi Auto Digi Auto Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal

36.77 36.78 36.83 36.45 36.28 36.02 36.03 36.05 36.03 35.98 36.37 36.36 36.38 36.40 36.39 36.05 36.04 36.27 36.28 36.10 35.91 36.23 36.60 36.44 35.76 35.13 34.94 33.57 33.75 33.82 34.99 36.06 36.11 35.16 35.27 34.73 35.39 35.24 35.30 36.21 35.31 35.50 35.55 33.77 35.83 35.87 35.72 35.72 35.31 35.37 34.59 35.72 35.18 35.31 35.70 35.86 36.06 35.03 35.46 36.30 36.45 36.42 35.49 36.50 36.52 34.64 33.65 33.65 33.71 33.13 33.25 32.08 33.41 33.13 33.81 34.86

Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal

Sal Sal

Sal Sal

Sal Sal Sal Sal Sal Sal Sal Sal

Sal Sal

Sal Sal Sal

Sal Sal Sal Sal Sal

δ18O (‰) 0.49 0.48 0.55 0.40 1.08 1.03 0.55 0.80 0.82 0.60 0.95 1.03 1.04 0.98 0.97 0.96 1.03 0.77 0.67 0.42 0.46 0.74 0.78 0.75 0.78 0.39 0.47 0.20 0.16 0.40 0.37 0.89 0.63 0.63 0.66 0.96 0.69 0.78 0.71 0.67 0.64 0.92 0.71 0.18 0.60 0.55 0.75 0.55 0.61 0.71 1.12 0.43 0.72 0.89 0.56 0.98 0.46 0.68 0.76 0.79 0.66 0.82 0.77 0.75 0.61 0.60 0.43 0.33 0.26 0.08 0.43 0.00 0.28 -0.03 0.41 0.77

δD (‰)

d-excess (‰)

Identified group

Analyzing laboratory

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

A/B A/B A A/B A A A A A A A A A A A A A A A A/B A/B A A A A A/B A/B B B B A/B A A A A A A A A A A A A B A A A A A A A A/B A A A A A/B A A A A A A A A A B B B B B B B B B A

PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL

R.D. Deshpande et al. / Marine Chemistry 157 (2013) 144–161

149

Table 1 (continued) Sr no

Sample code

Collection date

Cruise code

Long °E

Lat °N

Salinity instrument

Salinity

150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224

UMC-3716 UMC-3717 UMC-3706 UMC-3707 UMC-3708 UMC-3709 UMC-3710 UMC-3711 UMC-3712 UMC-3704 UMC-3713 UMC-3705 UMC-3616 UMC-3617 UMC-3618 UMC-3619 UMC-3620 UMC-3621 UMC-3644 UMC-3645 UMC-3646 UMC-3647 UMC-3648 UMC-3649 UMC-3650 UMC-3642 UMC-3651 UMC-3643 UMC-11179 UMC-11180 UMC-11181 UMC-11182 UMC-11183 UMC-11184 UMC-11185 UMC-3794 UMC-11186 UMC-11187 UMC-11188 UMC-11189 UMC-11190 UMC-11191 UMC-11192 UMC-11193 UMC-3795 UMC-3796 UMC-11194 UMC-3797 UMC-3817 UMC-3818 UMC-11195 UMC-11196 UMC-11197 UMC-11198 UMC-3798 UMC-3799 UMC-3819 UMC-11199 UMC-11200 UMC-11201 UMC-3791 UMC-3800 UMC-3801 UMC-3820 UMC-11202 UMC-11203 UMC-11204 UMC-3792 UMC-3821 UMC-3822 UMC-3823 UMC-11205 UMC-11206 UMC-11207 UMC-3793

21-Dec-08 22-Dec-08 5-Jan-09 5-Jan-09 6-Jan-09 6-Jan-09 6-Jan-09 7-Jan-09 7-Jan-09 8-Jan-09 8-Jan-09 9-Jan-09 4-Feb-09 4-Feb-09 5-Feb-09 5-Feb-09 5-Feb-09 5-Feb-09 6-Feb-09 6-Feb-09 6-Feb-09 6-Feb-09 7-Feb-09 7-Feb-09 8-Feb-09 9-Feb-09 9-Feb-09 10-Feb-09 10-Feb-09 11-Feb-09 11-Feb-09 12-Feb-09 12-Feb-09 12-Feb-09 12-Feb-09 12-Feb-09 13-Feb-09 14-Feb-09 14-Feb-09 15-Feb-09 15-Feb-09 15-Feb-09 16-Feb-09 16-Feb-09 16-Feb-09 16-Feb-09 17-Feb-09 17-Feb-09 18-Feb-09 18-Feb-09 18-Feb-09 18-Feb-09 18-Feb-09 18-Feb-09 18-Feb-09 18-Feb-09 19-Feb-09 19-Feb-09 19-Feb-09 19-Feb-09 19-Feb-09 19-Feb-09 19-Feb-09 20-Feb-09 20-Feb-09 20-Feb-09 20-Feb-09 20-Feb-09 21-Feb-09 21-Feb-09 21-Feb-09 21-Feb-09 21-Feb-09 21-Feb-09 21-Feb-09

SP-12/08 SP-12/08 MVK-126 MVK-126 MVK-126 MVK-126 MVK-126 MVK-126 MVK-126 MVK-126 MVK-126 MVK-126 SK-255 SK-255 SK-255 SK-255 SK-255 SK-255 MVK-128 MVK-128 MVK-128 MVK-128 MVK-128 MVK-128 MVK-128 MVK-128 MVK-128 MVK-128 SK-256 SK-256 SK-256 SK-256 SK-256 SK-256 SK-256 SK-262 SK-256 SK-256 SK-256 SK-256 SK-256 SK-256 SK-256 SK-256 SK-262 SK-262 SK-256 SK-262 MVK-129 MVK-129 SK-256 SK-256 SK-256 SK-256 SK-262 SK-262 MVK-129 SK-256 SK-256 SK-256 SK-262 SK-262 SK-262 MVK-129 SK-256 SK-256 SK-256 SK-262 MVK-129 MVK-129 MVK-129 SK-256 SK-256 SK-256 SK-262

73.00 73.69 75.00 74.50 74.00 73.50 73.00 73.58 73.40 73.75 73.22 74.35 75.71 75.41 75.51 74.27 73.82 73.82 75.50 74.98 74.50 74.00 73.42 73.42 73.47 74.00 73.05 74.75 72.13 70.04 69.40 67.87 67.62 66.65 66.53 70.75 66.64 65.49 65.52 64.42 64.19 64.00 65.02 65.02 63.99 64.98 66.18 67.02 75.50 75.00 67.05 67.03 67.03 67.05 68.00 68.73 73.50 69.00 69.00 69.02 68.27 69.93 69.07 72.67 69.95 70.17 70.17 65.00 72.73 73.10 73.67 70.37 71.25 72.44 67.02

15.24 15.56 10.13 10.23 10.32 10.42 10.48 9.83 9.33 8.72 8.83 9.03 10.38 10.72 11.13 12.53 12.65 13.22 10.03 10.15 10.22 10.30 10.42 10.48 9.53 8.82 8.42 9.22 17.10 18.35 18.90 20.19 20.38 21.16 21.28 11.25 21.17 21.74 21.75 21.80 21.83 21.78 21.85 21.87 22.01 22.00 20.94 22.00 9.97 10.00 21.08 21.05 21.05 21.04 21.97 22.13 10.23 20.35 20.39 20.82 21.00 21.00 21.00 10.48 20.92 20.92 20.90 21.00 10.00 8.38 8.67 18.41 17.87 17.32 19.82

Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Auto Sal Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Auto Sal Auto Sal Digi Auto Auto Sal Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Auto Sal Auto Sal Digi Auto Digi Auto Digi Auto Digi Auto Auto Sal Auto Sal Auto Sal Digi Auto Digi Auto Digi Auto Digi Auto Auto Sal Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Auto Sal

35.59 34.59 34.72 34.52 34.29 35.28 35.78 34.64 34.68 33.37 34.48 34.31 33.50 33.57 33.79 33.99 33.68 33.85 33.90 34.34 34.09 34.26 35.20 34.85 34.21 33.92 33.86 34.33 35.34 35.50 35.96 36.43 36.49 36.74 36.69 33.86 36.63 36.35 36.16 36.60 36.63 36.62 36.61 36.62 36.50 36.49 36.56 36.34 34.05 34.21 36.56 35.57 36.56 36.59 36.24 36.21 34.41 36.29 36.17 36.30 36.22 36.04 35.65 34.37 35.95 35.96 35.76 36.39 34.70 34.11 34.57 35.99 35.96 35.95 36.17

Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal

Sal Sal Sal Sal Sal Sal Sal

Sal Sal Sal Sal

Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal

δ18O (‰) 0.82 0.90 0.68 0.43 0.89 0.63 0.94 0.40 0.66 0.26 0.39 0.30 0.16 -0.01 0.20 0.19 0.15 0.22 0.48 0.60 0.16 0.50 0.70 0.26 0.57 0.23 0.33 0.06 0.57 0.52 1.02 0.77 0.99 0.82 1.01 0.91 0.83 1.00 0.95 0.74 0.71 0.88 0.91 1.21 0.84 0.74 1.13 0.68 0.23 0.38 1.17 1.05 1.04 1.26 0.83 1.29 0.28 1.01 0.71 0.87 0.72 0.64 0.90 0.08 1.26 1.16 0.78 0.75 0.30 0.04 0.10 1.31 1.14 1.10 0.89

δD (‰)

d-excess (‰)

Identified group

Analyzing laboratory

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

A A A A/B A A A A/B A B A/B A/B B B B B B B B A A/B A A A/B A B B A/B A A A A A A A A/B A A A A A A A A A A A A A/B A/B A A A A A A A/B A A A A A A A/B A A A A A/B A/B A/B A A A A

PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL

(continued on next page)

150

R.D. Deshpande et al. / Marine Chemistry 157 (2013) 144–161

Table 1 (continued) Sr no

Sample code

Collection date

Cruise code

Long °E

Lat °N

Salinity instrument

Salinity

225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300

UMC-3815 UMC-3816 UMC-3824 UMC-11208 UMC-11209 UMC-11210 UMC-3752 UMC-21528 UMC-21529 UMC-3754 UMC-3755 UMC-3756 UMC-3757 UMC-3610 UMC-3611 UMC-3612 UMC-3758 UMC-3613 UMC-3759 UMC-3614 UMC-3615 UMC-3750 UMC-3751 UMC-21530 UMC-21531 UMC-21532 UMC-21533 UMC-21534 UMC-21535 UMC-21536 UMC-21537 UMC-21538 UMC-21539 UMC-21540 UMC-21541 UMC-21542 UMC-21543 UMC-21544 UMC-21545 UMC-21546 UMC-21547 UMC-21548 UMC-21549 UMC-21550 UMC-21551 UMC-21552 UMC-21553 UMC-21554 UMC-21555 UMC-21556 UMC-21557 UMC-21558 UMC-21600 UMC-21601 UMC-21602 UMC-21603 UMC-21604 UMC-21605 UMC-21606 UMC-21607 UMC-21608 UMC-21609 UMC-21610 UMC-21611 UMC-21612 UMC-21613 UMC-21614 UMC-21615 UMC-21616 UMC-21617 UMC-21618 UMC-11211 UMC-11212 UMC-11213 UMC-11214 UMC-21619

22-Feb-09 22-Feb-09 22-Feb-09 22-Feb-09 22-Feb-09 22-Feb-09 1-Mar-09 2-Mar-09 2-Mar-09 4-Mar-09 5-Mar-09 6-Mar-09 7-Mar-09 8-Mar-09 8-Mar-09 8-Mar-09 8-Mar-09 9-Mar-09 9-Mar-09 10-Mar-09 10-Mar-09 10-Mar-09 11-Mar-09 12-Mar-09 13-Mar-09 15-Mar-09 17-Mar-09 17-Mar-09 19-Mar-09 20-Mar-09 24-Mar-09 25-Mar-09 27-Mar-09 28-Mar-09 29-Mar-09 30-Mar-09 31-Mar-09 3-Apr-09 4-Apr-09 6-Apr-09 6-Apr-09 6-Apr-09 6-Apr-09 7-Apr-09 7-Apr-09 7-Apr-09 8-Apr-09 8-Apr-09 8-Apr-09 9-Apr-09 9-Apr-09 9-Apr-09 22-Apr-09 23-Apr-09 23-Apr-09 23-Apr-09 24-Apr-09 24-Apr-09 24-Apr-09 25-Apr-09 25-Apr-09 26-Apr-09 26-Apr-09 27-Apr-09 27-Apr-09 27-Apr-09 28-Apr-09 28-Apr-09 4-May-09 7-May-09 8-May-09 9-May-09 10-May-09 10-May-09 10-May-09 10-May-09

MVK-129 MVK-129 MVK-129 SK-256 SK-256 SK-256 SSM-263 SK-257 SK-257 SSM-263 SSM-263 SSM-263 SSM-263 MVK-130 MVK-130 MVK-130 SSM-263 MVK-130 SSM-263 MVK-130 MVK-130 SSM-263 SSM-263 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 SK-257 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 SK-259 SK-259 SK-259 SK-259 ABP-36

74.75 75.67 74.25 72.83 73.03 73.09 68.33 71.62 71.62 64.10 65.28 66.68 66.17 74.00 73.60 73.47 66.27 73.00 68.63 72.75 73.17 70.01 70.00 72.00 71.67 71.24 71.06 71.06 70.86 71.62 70.38 70.23 69.98 69.89 69.81 69.64 69.47 69.06 69.06 68.56 68.66 68.63 68.64 68.99 69.44 69.88 69.94 69.05 69.15 69.71 70.00 70.42 70.32 68.28 67.22 66.07 65.03 63.92 62.85 61.75 59.60 58.92 58.37 58.00 57.18 57.77 58.28 57.52 59.08 59.75 60.50 75.06 75.82 76.13 76.73 61.52

9.22 9.72 8.97 17.12 17.02 17.02 18.46 14.54 14.00 21.82 21.83 22.18 21.18 10.05 9.90 9.50 21.08 8.50 20.74 10.57 10.48 21.00 18.49 13.43 13.43 13.34 14.24 14.03 13.37 14.54 13.00 14.37 13.73 13.09 15.01 14.47 13.78 14.93 12.97 13.77 13.46 13.48 13.91 13.00 13.02 13.02 14.00 14.00 14.15 14.72 15.00 14.66 13.00 11.33 10.50 9.67 8.83 8.00 7.17 6.33 7.17 8.00 8.83 9.67 10.50 11.33 12.17 13.00 8.00 7.15 6.33 10.35 8.42 7.87 7.02 5.40

Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Auto Sal Digi Auto Digi Auto Auto Sal Auto Sal Auto Sal Auto Sal Digi Auto Digi Auto Digi Auto Auto Sal Digi Auto Auto Sal Digi Auto Digi Auto Auto Sal Auto Sal Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto

34.66 34.13 34.35 35.73 35.15 35.14 35.93 35.01 35.12 36.48 36.51 36.57 36.57 34.35 34.19 34.46 36.59 34.74 35.67 34.20 34.11 36.09 35.67 35.85 35.74 35.88 35.87 35.69 34.55 35.01 35.76 35.73 35.34 36.31 35.89 35.84 36.27 36.38 35.68 36.19 35.73 35.76 35.70 35.67 35.84 35.73 35.73 35.78 35.77 35.79 35.82 35.76 35.14 35.13 35.20 34.08 34.19 34.27 34.61 34.58 34.69 34.73 34.80 34.72 35.02 35.56 35.28 35.25 34.74 34.62 34.60 35.02 34.95 35.09 35.58 35.13

Sal Sal Sal Sal Sal Sal Sal Sal

Sal Sal Sal Sal Sal Sal

Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal

δ18O (‰) 0.29 0.16 0.25 0.98 0.91 0.70 0.60 0.96 0.70 1.26 1.31 0.73 0.69 0.57 0.15 0.39 1.16 0.07 0.64 -0.10 0.41 0.84 0.65 0.80 0.73 0.96 0.80 0.74 0.89 0.64 0.84 0.89 0.68 1.04 0.72 0.85 1.02 0.96 0.83 1.17 0.95 1.33 1.04 1.31 0.96 1.03 0.96 0.87 1.95 0.99 0.93 0.91 1.09 0.76 0.94 1.19 0.66 1.71 0.95 0.76 1.19 0.96 1.35 0.99 1.18 1.35 1.32 1.78 1.28 1.15 1.57 0.74 0.63 0.67 0.67 0.80

δD (‰)

d-excess (‰)

Identified group

Analyzing laboratory

– – – – – – – 4.94 6.13 – – – – – – – – – – – – – – 7.85 6.72 7.12 6.67 6.95 6.61 6.46 7.00 6.82 5.62 7.15 7.10 6.82 7.78 7.60 6.24 7.01 6.19 6.83 6.73 6.58 5.79 6.51 6.18 6.37 7.06 6.64 6.73 5.69 7.44 6.44 7.26 4.92 5.30 6.51 6.06 5.55 6.26 6.12 6.52 6.40 6.70 6.87 6.72 7.23 5.67 5.71 5.88 – – – – 4.68

– – – – – – – −2.71 0.51 – – – – – – – – – – – – – – 1.42 0.89 −0.53 0.26 1.07 −0.53 1.38 0.25 −0.32 0.21 −1.14 1.34 0.01 −0.38 −0.09 −0.39 −2.32 −1.44 −3.83 −1.58 −3.88 −1.90 −1.71 −1.47 −0.62 −8.58 −1.25 −0.67 −1.60 −1.26 0.39 −0.24 −4.63 0.03 −7.17 −1.56 −0.55 −3.25 −1.58 −4.24 −1.55 −2.77 −3.94 −3.80 −7.03 −4.54 −3.47 −6.66 – – – – −1.74

A/B A/B A/B A A A A A A A A A A A A/B A/B A

PRL PRL PRL PRL PRL PRL PRL NIH NIH PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH PRL PRL PRL PRL NIH

A A/B A/B A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A

R.D. Deshpande et al. / Marine Chemistry 157 (2013) 144–161

151

Table 1 (continued) Sr no

Sample code

Collection date

Cruise code

Long °E

Lat °N

Salinity instrument

Salinity

301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375

UMC-11215 UMC-11216 UMC-11217 UMC-21620 UMC−21621 UMC-21623 UMC-21624 UMC-21625 UMC-21622 UMC-21626 UMC-21627 UMC-21628 UMC-21629 UMC-21630 UMC-21631 UMC-21632 UMC-21633 UMC-11218 UMC-11219 UMC-11220 UMC-11221 UMC-11222 UMC-11223 UMC-11224 UMC-11225 UMC-11226 UMC-11227 UMC-11228 UMC-11229 UMC-11230 UMC-11231 UMC-11232 UMC-11233 UMC-11234 UMC-11235 UMC-11236 UMC-11237 UMC-11238 UMC-11239 UMC-11240 UMC-11241 UMC-11242 UMC-11243 UMC-11244 UMC-11245 UMC-11246 UMC-11247 UMC-11249 UMC-11250 UMC-11251 UMC-11252 UMC-11253 UMC-11254 UMC-11255 UMC-11256 UMC-11257 UMC-11258 UMC-11259 UMC-11260 UMC-11261 UMC-11262 UMC-11263 UMC-11264 UMC-11265 UMC-11266 UMC-11267 UMC-11268 UMC-11269 UMC-11270 UMC-11271 UMC-11272 UMC-11273 UMC-21505 UMC-21506 UMC-21507

11-May-09 11-May-09 11-May-09 11-May-09 11-May-09 23-May-09 23-May-09 23-May-09 23-May-09 24-May-09 24-May-09 24-May-09 24-May-09 25-May-09 25-May-09 25-May-09 25-May-09 26-May-09 31-May-09 31-May-09 01-Jun-09 01-Jun-09 01-Jun-09 03-Jun-09 03-Jun-09 03-Jun-09 04-Jun-09 04-Jun-09 04-Jun-09 08-Jun-09 08-Jun-09 10-Jun-09 11-Jun-09 11-Jun-09 12-Jun-09 12-Jun-09 13-Jun-09 04-Sep-09 11-Sep-09 12-Sep-09 12-Sep-09 12-Sep-09 12-Sep-09 13-Sep-09 13-Sep-09 13-Sep-09 14-Sep-09 16-Sep-09 16-Sep-09 16-Sep-09 17-Sep-09 17-Sep-09 17-Sep-09 17-Sep-09 17-Sep-09 18-Sep-09 18-Sep-09 18-Sep-09 18-Sep-09 18-Sep-09 26-Sep-09 27-Sep-09 27-Sep-09 27-Sep-09 28-Sep-09 28-Sep-09 28-Sep-09 29-Sep-09 29-Sep-09 29-Sep-09 30-Sep-09 30-Sep-09 6-Nov-09 6-Nov-09 7-Nov-09

SK-259 SK-259 SK-259 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 ABP-36 SK-259 SSM-267 SSM-267 SSM-267 SSM-267 SSM-267 SSM-267 SSM-267 SSM-267 SSM-267 SSM-267 SSM-267 SSM-267 SSM-267 SSM-267 SSM-267 SSM-267 SSM-267 SSM-267 SSM-267 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-20/09 SP-21/09 SP-21/09 SP-21/09 SP-21/09 SP-21/09 SP-21/09 SP-21/09 SP-21/09 SP-21/09 SP-21/09 SP-21/09 SP-21/09 SK-265 SK-265 SK-265

78.27 78.49 78.84 62.47 63.50 64.30 65.02 65.73 66.47 67.40 67.78 68.50 69.22 70.57 70.75 71.53 71.95 78.75 76.86 76.74 76.61 76.40 76.35 75.95 76.00 76.28 75.56 75.85 76.15 74.83 74.94 75.00 74.92 75.05 75.50 75.87 75.50 78.73 78.38 78.30 77.92 77.50 77.08 76.75 76.53 76.31 76.12 75.83 75.72 75.40 75.21 75.01 74.78 74.65 74.37 74.16 74.14 74.13 73.97 73.79 73.48 73.30 73.24 73.16 73.04 72.76 72.63 72.50 72.51 72.55 72.61 72.60 68.15 67.22 65.38

4.77 4.47 3.92 4.67 3.83 4.50 5.33 6.17 7.00 7.83 8.67 9.50 10.33 11.17 12.00 12.83 13.67 7.32 8.50 8.51 8.49 8.47 8.44 9.01 8.99 9.01 9.96 10.00 9.96 11.22 11.24 11.23 12.01 11.98 10.51 10.48 9.95 8.90 8.74 8.29 8.08 8.04 8.20 8.52 8.86 9.24 9.63 10.42 10.81 11.21 11.62 12.01 12.39 12.80 13.19 13.56 13.99 14.42 14.78 15.15 15.77 16.25 16.71 17.13 17.52 18.33 18.75 18.76 19.58 20.04 20.42 20.87 12.00 11.29 10.23

Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Auto Sal Auto Sal Auto Sal

34.56 34.54 34.57 35.33 35.09 34.53 34.70 35.72 35.04 35.19 35.09 35.52 36.35 35.92 35.94 35.93 35.95 35.17 35.18 35.20 35.23 35.17 35.36 35.16 35.61 35.37 35.71 35.97 33.80 35.80 35.70 35.69 35.37 35.64 35.10 35.27 35.35 35.31 35.39 35.40 35.24 35.20 35.28 35.28 35.10 35.28 34.35 34.07 33.94 34.01 34.25 33.99 32.43 31.89 33.96 34.40 35.16 35.45 34.88 35.59 34.75 34.99 35.06 35.71 34.99 35.22 34.46 35.11 34.27 32.27 31.00 31.82 33.65 36.05 35.92

Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal

δ18O (‰) 0.29 0.68 0.35 1.20 0.52 0.47 0.87 1.04 0.64 0.60 0.49 1.35 0.89 1.18 0.90 1.03 0.37 0.38 0.14 0.57 0.50 0.49 0.45 0.65 0.47 0.66 0.54 0.40 0.63 0.86 0.78 0.67 0.80 0.70 0.50 0.80 0.31 0.75 0.46 0.45 0.56 0.28 0.67 0.63 0.60 0.65 0.37 0.47 0.33 0.44 0.29 0.41 0.40 0.69 0.56 1.01 0.90 0.90 1.06 0.86 0.55 0.83 0.60 0.69 0.67 0.77 0.86 0.99 0.77 0.39 0.69 1.40 1.52 1.10

δD (‰)

d-excess (‰)

Identified group

Analyzing laboratory

– – – 5.38 6.08 4.52 5.77 5.83 5.61 6.40 6.21 6.12 7.31 6.58 6.82 7.44 7.24 – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 7.83 8.78 7.54

– – – −4.25 1.93 0.77 −1.19 −2.50 5.61 1.25 1.43 2.23 −3.48 −0.50 −2.63 0.23 −1.00 – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – −3.41 −3.38 −1.24

A/B A A/B A A A/B A A A/B A A A/B A A A A A A/B A/B A/B A A A/B A/B A A/B A A B A A A A A A A A A/B A A A/B A/B A/B A A A A A/B B A/B A/B B B B A/B A A/B A A A A A A A A A A A A A/B B A/B A/B A A

PRL PRL PRL NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL NIH NIH NIH

(continued on next page)

152

R.D. Deshpande et al. / Marine Chemistry 157 (2013) 144–161

Table 1 (continued) Sr no

Sample code

Collection date

Cruise code

Long °E

Lat °N

Salinity instrument

Salinity

376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451

UMC-21508 UMC-21509 UMC-21510 UMC-21511 UMC-21512 UMC-21513 UMC-21514 UMC-21515 UMC-21471 UMC-21472 UMC-21473 UMC-21474 UMC-21516 UMC-21517 UMC-21519 UMC-21520 UMC-21521 UMC-21522 UMC-21523 UMC-21524 UMC-21525 UMC-21526 UMC-21527 UMC-21463 UMC-21464 UMC-21465 UMC-21466 UMC-21467 UMC-21468 UMC-11274 UMC-11275 UMC-11276 UMC-21469 UMC-11277 UMC-11278 UMC-21477 UMC-21478 UMC-21479 UMC-21480 UMC-21481 UMC-21482 UMC-21483 UMC-21484 UMC-21485 UMC-21486 UMC-21487 UMC-21488 UMC-21489 UMC-21490 UMC-21491 UMC-21492 UMC-21493 UMC-21634 UMC-21635 UMC-21636 UMC-21494 UMC-21495 UMC-21637 UMC-21638 UMC-21639 UMC-21640 UMC-21496 UMC-21497 UMC-21641 UMC-21642 UMC-21643 UMC-21644 UMC-21645 UMC-21646 UMC-21647 UMC-21648 UMC-21649 UMC-21650 UMC-21651 UMC-21652 UMC-21653

7-Nov-09 8-Nov-09 8-Nov-09 9-Nov-09 10-Nov-09 11-Nov-09 11-Nov-09 12-Nov-09 1-Dec-09 1-Dec-09 1-Dec-09 2-Dec-09 2-Dec-09 2-Dec-09 2-Dec-09 3-Dec-09 3-Dec-09 3-Dec-09 4-Dec-09 4-Dec-09 4-Dec-09 5-Dec-09 5-Dec-09 10-Dec-09 10-Dec-09 11-Dec-09 11-Dec-09 12-Dec-09 12-Dec-09 12-Dec-09 12-Dec-09 13-Dec-09 14-Dec-09 14-Dec-09 22-Dec-09 8-Jan-10 8-Jan-10 8-Jan-10 9-Jan-10 9-Jan-10 9-Jan-10 6-Feb-10 6-Feb-10 6-Feb-10 7-Feb-10 7-Feb-10 7-Feb-10 8-Feb-10 8-Feb-10 20-Feb-10 20-Feb-10 20-Feb-10 20-Feb-10 20-Feb-10 20-Feb-10 21-Feb-10 21-Feb-10 21-Feb-10 21-Feb-10 21-Feb-10 21-Feb-10 22-Feb-10 22-Feb-10 23-Feb-10 24-Feb-10 24-Feb-10 24-Feb-10 24-Feb-10 24-Feb-10 24-Feb-10 24-Feb-10 25-Feb-10 25-Feb-10 25-Feb-10 25-Feb-10 25-Feb-10

SK-265 SK-265 SK-265 SK-265 SK-265 SK-265 SK-265 SK-265 MVK-145 MVK-145 MVK-145 MVK-145 SK-265 SK-265 SK-265 SK-265 SK-265 SK-265 SK-265 SK-265 SK-265 SK-265 SK-265 MVK-144 MVK-144 MVK-144 MVK-144 MVK-144 MVK-144 SP-A1 SP-A1 SP-A1 MVK-144 SP-A1 SP-A1 MVK-146 MVK-146 MVK-146 MVK-146 MVK-146 MVK-146 MVK-148 MVK-148 MVK-148 MVK-148 MVK-148 MVK-148 MVK-148 MVK-148 MVK-149 MVK-149 MVK-149 SPS-04/10 SPS-04/10 SPS-04/10 MVK-149 MVK-149 SPS-04/10 SPS-04/10 SPS-04/10 SPS-04/10 MVK-149 MVK-149 SPS-04/10 SPS-04/10 SPS-04/10 SPS-04/10 SPS-04/10 SPS-04/10 SPS-04/10 SPS-04/10 SPS-04/10 SPS-04/10 SPS-04/10 SPS-04/10 SPS-04/10

64.59 65.00 65.00 65.00 65.00 65.00 65.02 65.00 72.77 73.50 74.00 74.53 65.03 68.27 68.49 69.05 69.20 69.38 70.13 70.25 70.35 70.54 71.05 75.55 74.75 73.98 73.02 73.23 73.45 72.76 73.02 73.43 75.70 74.06 75.15 73.02 73.53 74.08 74.53 75.03 75.58 75.50 75.00 74.50 74.00 73.50 73.00 73.63 73.27 72.75 73.00 73.50 78.30 77.98 77.57 74.00 74.50 76.81 76.56 76.33 76.19 75.00 75.55 76.09 75.94 75.79 75.55 75.37 75.14 74.91 74.75 74.56 74.51 74.30 74.05 74.05

10.00 9.00 8.00 7.00 5.00 4.00 2.00 1.00 10.55 10.42 10.32 10.57 0.00 2.00 4.00 5.32 6.29 7.25 9.00 9.48 10.32 11.36 12.21 9.67 9.23 8.83 8.48 9.00 9.53 18.15 17.41 15.86 10.00 14.86 14.56 10.52 10.42 10.32 10.23 10.13 10.03 10.05 10.13 10.22 10.32 10.42 10.50 9.50 9.00 10.55 10.45 10.25 8.31 8.08 7.98 10.05 10.03 8.44 8.75 9.12 9.44 10.00 9.98 9.97 10.37 10.75 11.26 11.63 11.99 12.34 12.70 13.08 13.49 13.94 14.31 14.72

Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Digi Auto Digi Auto Digi Auto Auto Sal Digi Auto Digi Auto Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Digi Auto Digi Auto Digi Auto Auto Sal Auto Sal Digi Auto Digi Auto Digi Auto Digi Auto Auto Sal Auto Sal Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto

33.86 36.62 36.42 36.27 35.86 35.91 35.39 35.21 36.64 35.67 35.52 35.74 35.40 36.00 35.67 36.27 36.51 36.37 36.62 36.83 36.61 36.33 35.86 35.15 35.91 35.37 35.50 36.32 36.00 35.00 34.96 34.79 34.89 34.45 34.81 35.79 35.77 33.99 33.41 32.95 32.93 33.59 34.30 34.83 33.89 33.78 32.83 33.17 33.18 33.59 34.02 33.78 34.17 34.17 33.64 33.86 33.70 33.46 33.39 33.63 33.61 33.70 33.44 33.64 33.87 33.90 33.96 33.13 34.24 34.40 34.43 34.21 34.14 33.98 34.13 33.60

Sal Sal Sal Sal Sal

Sal Sal Sal

Sal Sal Sal Sal

Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal

δ18O (‰) 1.06 1.38 1.34 1.32 1.69 1.05 1.09 1.58 1.49 1.54 1.36 1.24 0.90 0.91 1.38 1.30 1.22 1.28 1.32 1.25 1.46 1.43 1.30 0.61 0.67 0.76 0.85 0.99 1.13 0.63 0.56 0.41 1.10 0.86 0.79 1.09 1.34 0.81 1.16 1.12 0.88 0.52 0.60 1.19 0.97 0.52 0.75 0.70 0.60 1.00 1.24 0.96 0.49 1.41 0.42 1.06 0.52 0.38 0.33 0.32 0.31 1.52 0.63 0.30 0.39 0.25 0.31 0.33 0.64 0.60 0.51 0.31 0.52 0.37 0.48 0.41

δD (‰)

d-excess (‰)

Identified group

Analyzing laboratory

7.65 8.28 8.03 8.02 7.28 6.87 5.92 6.25 8.97 8.06 7.57 8.29 4.92 4.91 6.66 7.02 6.72 6.84 7.23 6.80 5.96 6.49 6.13 5.56 5.70 5.64 6.55 6.99 7.96 – – – 7.87 – – 7.65 7.11 6.52 7.31 7.07 5.53 4.29 5.03 6.79 6.13 3.92 4.15 3.64 5.03 4.39 4.85 3.41 4.72 4.20 4.05 3.88 3.47 2.95 3.02 3.39 3.64 5.62 4.64 4.60 4.07 4.36 4.58 4.48 4.67 4.40 5.07 5.23 5.46 4.92 4.61 4.53

−0.82 −2.75 −2.69 −2.57 −6.26 −1.49 −2.79 −6.42 −2.98 −4.26 −3.34 −1.64 −2.30 −2.35 −4.38 −3.39 −3.05 −3.39 −3.34 −3.19 −5.69 −4.98 −4.31 0.65 0.37 −0.43 −0.23 −0.92 −1.07 – – – −0.93 – – −1.05 −3.65 0.07 −1.94 −1.87 −1.51 0.15 0.20 −2.74 −1.66 −0.22 −1.86 −1.97 0.25 −3.61 −5.08 −4.29 0.83 −7.09 0.66 −4.56 −0.69 −0.09 0.39 0.85 1.13 −6.56 −0.40 2.19 0.94 2.32 2.11 1.84 −0.43 −0.39 0.99 2.75 1.29 1.99 0.75 1.27

A/B A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A/B A A A A A A/B A/B A/B A/B A/B A A A/B A/B A/B A/B A/B A/B A A/B A/B A B A/B A/B B B B B A/B A/B B B B B B A A A A/B A B A/B B

NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH PRL PRL PRL NIH PRL PRL NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH

R.D. Deshpande et al. / Marine Chemistry 157 (2013) 144–161

153

Table 1 (continued) Sr no

Sample code

Collection date

Cruise code

Long °E

Lat °N

Salinity instrument

Salinity

452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526

UMC-11279 UMC-11280 UMC-11281 UMC-11282 UMC-11283 UMC-11284 UMC-11285 UMC-11286 UMC-11287 UMC-11288 UMC-11289 UMC-11290 UMC-11291 UMC-11292 UMC-11293 UMC-11294 UMC-11295 UMC-11296 UMC-11297 UMC-11298 UMC-11299 UMC-11300 UMC-11301 UMC-11302 UMC-11303 UMC-11304 UMC-11305 UMC-11306 UMC-11307 UMC-11308 UMC-11309 UMC-11310 UMC-11311 UMC-11312 UMC-11313 UMC-21498 UMC-21499 UMC-21500 UMC-21501 UMC-21502 UMC-21503 UMC-21504 UMC-21349 UMC-21350 UMC-21351 UMC-21352 UMC-21353 UMC-21354 UMC-21355 UMC-21356 UMC-21357 UMC-21358 UMC-21359 UMC-21360 UMC-21361 UMC-21362 UMC-21363 UMC-21364 UMC-21365 UMC-21366 UMC-21367 UMC-21368 UMC-21369 UMC-21370 UMC-21371 UMC-21372 UMC-21373 UMC-21374 UMC-21375 UMC-21376 UMC-21377 UMC-21378 UMC-21379 UMC-21559 UMC-21560

27-Feb-10 27-Feb-10 27-Feb-10 28-Feb-10 01-Mar-10 01-Mar-10 01-Mar-10 01-Mar-10 03-Mar-10 03-Mar-10 07-Mar-10 07-Mar-10 08-Mar-10 09-Mar-10 09-Mar-10 10-Mar-10 10-Mar-10 10-Mar-10 11-Mar-10 11-Mar-10 11-Mar-10 11-Mar-10 12-Mar-10 12-Mar-10 12-Mar-10 13-Mar-10 13-Mar-10 13-Mar-10 14-Mar-10 21-Mar-10 22-Mar-10 22-Mar-10 22-Mar-10 23-Mar-10 23-Mar-10 25-Mar-10 25-Mar-10 25-Mar-10 25-Mar-10 26-Mar-10 26-Mar-10 26-Mar-10 4-Jun-10 4-Jun-10 4-Jun-10 4-Jun-10 4-Jun-10 5-Jun-10 5-Jun-10 5-Jun-10 6-Jun-10 6-Jun-10 6-Jun-10 7-Jun-10 7-Jun-10 7-Jun-10 8-Jun-10 8-Jun-10 8-Jun-10 8-Jun-10 9-Jun-10 9-Jun-10 9-Jun-10 10-Jun-10 10-Jun-10 10-Jun-10 10-Jun-10 11-Jun-10 11-Jun-10 12-Jun-10 12-Jun-10 13-Jun-10 13-Jun-10 10-Jul-10 11-Jul-10

SPS-05/10 SPS-05/10 SPS-05/10 SPS-05/10 SPS-05/10 SPS-05/10 SPS-05/10 SPS-05/10 SPS-05/10 SPS-05/10 SPS-05/10 SPS-05/10 SPS-05/10 SPS-05/10 SPS-05/10 SP-B SP-B SP-B SP-B SP-B SP-B SP-B SP-B SP-B SP-B SP-B SP-B SP-B SP-B SP-B SP-B SP-B SP-B SP-B SP-B MVK-151 MVK-151 MVK-151 MVK-151 MVK-151 MVK-151 MVK-151 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-260 SK-274 SK-274

74.34 74.37 74.48 74.67 74.72 74.92 75.10 75.25 75.70 76.13 76.20 76.31 76.44 76.81 77.12 77.94 77.15 76.77 76.35 76.10 75.92 75.77 75.60 75.49 75.53 75.25 74.97 74.82 74.55 74.60 74.37 74.20 74.07 73.87 73.69 72.75 73.02 73.48 73.97 74.47 75.00 75.50 72.00 71.58 71.17 70.72 70.30 68.53 67.82 67.46 66.40 65.71 65.09 65.12 65.06 65.02 65.01 65.02 65.01 65.02 64.67 65.01 65.00 65.00 65.00 65.02 65.00 65.00 64.93 64.93 64.98 64.98 65.00 78.32 76.73

17.33 13.94 13.70 13.16 12.82 12.48 12.09 11.84 10.77 9.96 9.75 9.24 8.94 8.47 8.17 7.97 8.04 8.24 8.75 9.12 9.52 10.00 10.45 10.94 11.37 11.77 12.05 12.45 12.82 13.07 13.63 14.03 14.47 14.87 15.38 10.57 10.52 10.42 10.33 10.23 10.15 10.05 8.25 8.37 8.47 8.56 8.66 9.13 9.32 9.40 9.65 9.81 9.96 10.00 9.53 8.77 8.01 7.88 6.99 6.77 6.00 5.58 5.00 4.43 4.02 3.67 3.00 2.00 2.00 1.12 1.02 0.01 1.00 6.57 7.55

Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Auto Sal Auto Sal

34.04 33.72 34.05 34.37 34.88 34.28 34.40 34.41 34.21 34.16 34.10 34.21 34.24 34.24 34.25 34.12 34.21 34.15 34.07 34.10 33.98 33.92 33.94 34.43 34.67 34.65 34.31 34.63 34.52 34.57 34.53 34.10 34.58 34.92 34.06 34.37 34.61 34.26 34.16 34.14 34.11 34.01 35.28 35.08 35.34 35.44 35.22 35.82 35.71 35.88 35.95 35.88 35.64 35.65 35.69 35.66 35.66 35.66 35.64 35.55 35.51 35.46 35.40 34.76 34.81 34.78 35.02 35.14 34.76 35.16 35.32 35.62 35.51 34.49 35.27

Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal

Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal

δ18O (‰) 0.50 0.62 0.56 0.45 0.55 0.58 0.60 0.63 0.45 0.24 0.50 0.17 0.66 0.40 0.57 0.43 0.57 0.49 0.15 0.48 0.16 0.54 0.13 0.60 0.66 0.77 0.66 0.39 0.53 0.49 0.41 1.85 0.88 0.79 1.02 0.81 1.34 1.31 0.96 1.00 0.97 0.68 0.73 0.62 0.83 0.70 0.75 0.73 0.76 0.83 0.87 0.81 0.87 0.81 0.78 0.98 0.88 0.78 0.79 0.76 0.82 0.84 0.76 0.64 0.92 0.57 0.57 0.63 0.62 0.70 0.60 1.51 0.70 0.84 0.96

δD (‰)

d-excess (‰)

Identified group

Analyzing laboratory

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – 5.69 6.33 5.39 4.72 4.51 4.71 3.99 7.15 6.39 5.59 5.89 6.16 6.92 6.50 6.89 7.55 6.74 6.84 7.19 6.78 6.83 6.16 6.59 6.04 5.83 6.47 6.67 6.62 5.39 5.85 5.54 6.24 6.02 5.14 6.11 5.51 7.91 6.40 5.47 6.42

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – −0.81 −4.37 −5.08 −2.94 −3.48 −3.03 −1.43 1.32 1.44 −1.05 0.32 0.17 1.06 0.45 0.26 0.58 0.24 −0.13 0.74 0.58 −0.99 −0.92 0.37 −0.29 −0.27 −0.11 −0.03 0.56 0.25 −1.51 0.99 1.67 0.98 0.14 0.51 0.69 −4.20 0.79 −1.22 −1.30

A/B A/B A A/B A A A A A/B A/B A/B A/B A A/B A A/B A A/B A/B A/B B A/B B A A A A A/B A A/B A/B A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A

PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL PRL NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH

(continued on next page)

154

R.D. Deshpande et al. / Marine Chemistry 157 (2013) 144–161

Table 1 (continued) Sr no

Sample code

Collection date

Cruise code

Long °E

Lat °N

Salinity instrument

Salinity

δ18O (‰)

δD (‰)

d-excess (‰)

Identified group

Analyzing laboratory

527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602

UMC-21561 UMC-21562 UMC-21563 UMC-21564 UMC-21565 UMC-21566 UMC-21567 UMC-21568 UMC-21569 UMC-21570 UMC-21572 UMC-21573 UMC-21574 UMC-21576 UMC-21577 UMC-21578 UMC-21579 UMC-21580 UMC-21582 UMC-21583 UMC-21584 UMC-21585 UMC-21586 UMC-21587 UMC-21588 UMC-21448 UMC-21449 UMC-21380 UMC-21381 UMC-21382 UMC-21450 UMC-21451 UMC-21383 UMC-21384 UMC-21385 UMC-21452 UMC-21386 UMC-21387 UMC-21388 UMC-21389 UMC-21390 UMC-21391 UMC-21392 UMC-21393 UMC-21394 UMC-21453 UMC-21454 UMC-21455 UMC-21456 UMC-21457 UMC-21458 UMC-21459 UMC-21460 UMC-21461 UMC-21462 UMC-21677 UMC-21678 UMC-21679 UMC-21680 UMC-21681 UMC-21395 UMC-21396 UMC-21682 UMC-21397 UMC-21398 UMC-21399 UMC-21654 UMC-21655 UMC-21656 UMC-21657 UMC-21658 UMC-21659 UMC-21683 UMC-21400 UMC-21401 UMC-21402

11-Jul-10 11-Jul-10 12-Jul-10 12-Jul-10 12-Jul-10 13-Jul-10 13-Jul-10 13-Jul-10 14-Jul-10 14-Jul-10 18-Aug-10 19-Aug-10 19-Aug-10 24-Aug-10 25-Aug-10 26-Aug-10 26-Aug-10 27-Aug-10 2-Sep-10 3-Sep-10 4-Sep-10 5-Sep-10 5-Sep-10 7-Sep-10 7-Sep-10 13-Oct-10 13-Oct-10 14-Oct-10 14-Oct-10 14-Oct-10 14-Oct-10 14-Oct-10 15-Oct-10 15-Oct-10 15-Oct-10 15-Oct-10 16-Oct-10 16-Oct-10 16-Oct-10 17-Oct-10 17-Oct-10 17-Oct-10 18-Oct-10 18-Oct-10 18-Oct-10 19-Oct-10 19-Oct-10 20-Oct-10 20-Oct-10 20-Oct-10 20-Oct-10 21-Oct-10 21-Oct-10 21-Oct-10 22-Oct-10 23-Oct-10 23-Oct-10 23-Oct-10 23-Oct-10 24-Oct-10 25-Oct-10 25-Oct-10 25-Oct-10 26-Oct-10 26-Oct-10 26-Oct-10 26-Oct-10 26-Oct-10 26-Oct-10 26-Oct-10 26-Oct-10 26-Oct-10 26-Oct-10 27-Oct-10 27-Oct-10 27-Oct-10

SK-274 SK-274 SK-274 SK-274 SK-274 SK-274 SK-274 SK-274 SK-274 SK-274 SK-275 SK-275 SK-275 SK-275 SK-275 SK-275 SK-275 SK-275 SK-275 SK-275 SK-275 SK-275 SK-275 SK-275 SK-275 SPS-C SPS-C SG-A SG-A SG-A SPS-C SPS-C SG-A SG-A SG-A SPS-C SG-A SG-A SG-A SG-A SG-A SG-A SG-A SG-A SG-A SPS-C SPS-C SPS-C SPS-C SPS-C SPS-C SPS-C SPS-C SPS-C SPS-C SPS-E SPS-E SPS-E SPS-E SPS-E SG-A SG-A SPS-E SG-A SG-A SG-A SPS-D SPS-D SPS-D SPS-D SPS-D SPS-D SPS-E SG-A SG-A SG-A

76.00 75.98 75.98 75.98 75.90 75.68 75.57 75.45 75.23 75.15 72.18 71.02 70.78 71.00 70.98 71.18 71.25 71.25 71.47 71.52 71.53 71.60 71.65 71.65 71.70 78.10 77.82 73.25 73.33 73.56 77.31 76.98 73.66 73.88 74.05 75.99 74.18 73.77 73.57 73.55 73.54 73.52 73.58 73.65 73.69 75.90 75.73 75.69 75.58 75.37 75.03 74.87 74.72 74.47 74.20 76.11 75.91 75.82 75.65 75.52 73.57 74.22 74.29 73.24 73.15 73.33 73.74 73.88 74.03 74.22 74.41 74.57 75.00 73.44 73.47 73.66

7.98 8.00 8.00 8.00 7.30 5.58 4.68 3.80 2.25 1.38 10.50 10.82 11.00 10.97 10.97 12.63 12.33 11.15 12.23 11.77 12.85 11.67 11.35 12.08 11.02 8.10 8.01 14.47 14.44 14.42 8.08 8.35 14.36 14.15 14.24 10.03 14.14 13.79 13.77 13.93 13.72 13.59 13.54 14.06 14.70 10.40 10.78 11.23 11.31 11.66 11.97 12.38 12.80 13.51 14.02 10.03 10.33 10.70 11.52 11.41 15.48 15.59 11.77 15.39 15.32 15.19 14.78 14.42 14.12 13.71 13.28 12.83 11.99 15.09 14.78 14.71

Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto

34.90 34.90 35.25 35.58 35.52 35.56 35.46 35.53 34.87 35.23 35.59 36.10 36.07 36.16 36.16 36.11 36.05 36.19 35.93 35.98 35.98 35.88 35.95 36.80 35.99 35.06 35.10 33.14 32.20 33.56 35.15 34.21 33.67 33.27 33.49 28.85 34.36 34.19 34.62 34.70 34.80 34.49 34.79 34.35 34.43 29.63 31.74 33.56 33.00 33.77 33.07 32.99 33.46 33.28 33.54 29.62 31.24 32.91 33.18 33.18 34.00 34.03 33.13 34.45 34.41 34.29 32.85 33.69 33.85 31.75 32.47 30.94 32.92 34.38 34.57 34.13

0.93 0.80 1.24 0.81 0.53 0.74 0.80 0.91 1.01 0.94 1.20 1.16 1.08 1.14 0.84 0.94 1.35 1.29 0.87 1.05 0.99 1.29 0.97 1.18 0.96 0.94 0.73 0.45 0.34 0.45 1.40 0.46 0.62 0.49 0.41 0.00 0.38 0.64 0.65 0.72 0.66 0.33 0.60 0.50 0.05 0.05 0.26 1.88 0.59 0.99 0.55 0.56 0.51 0.47 0.93 0.09 −0.04 0.36 0.44 0.11 0.35 0.23 0.37 0.53 0.19 0.27 0.26 0.62 0.49 0.11 0.38 0.21 0.21 0.29 0.37 0.25

5.77 6.06 6.07 4.63 4.61 4.76 4.55 5.58 5.78 5.86 7.54 8.14 8.40 8.75 8.27 7.93 8.51 8.27 8.41 7.98 8.05 8.80 8.43 8.42 8.07 6.47 6.64 5.36 4.79 4.34 7.29 6.85 4.40 4.61 4.73 1.96 4.17 5.08 5.43 6.09 5.89 6.40 6.44 6.77 4.17 2.65 4.28 6.90 5.41 5.98 5.33 5.61 4.83 4.47 5.61 0.56 0.98 3.15 3.14 1.13 6.24 5.07 3.23 6.64 5.94 5.28 3.87 5.43 6.11 2.66 3.60 2.77 2.02 5.14 5.50 4.83

−1.67 −0.32 −3.82 −1.87 0.34 −1.20 −1.87 −1.70 −2.32 −1.65 −2.05 −1.16 −0.20 −0.34 1.55 0.41 −2.32 −2.01 1.45 −0.43 0.14 −1.49 0.70 −1.01 0.42 −1.08 0.79 1.79 2.06 0.71 −3.89 3.16 −0.53 0.69 1.46 1.93 1.14 −0.03 0.22 0.36 0.58 3.79 1.68 2.77 3.78 2.23 2.18 −8.16 0.71 −1.94 0.97 1.14 0.79 0.74 −1.85 −0.20 1.27 0.25 −0.39 0.28 3.41 3.22 0.29 2.44 4.41 3.09 1.82 0.44 2.18 1.77 0.60 1.06 0.32 2.85 2.53 2.79

A A A A A A A A A A A A A A A A A A A A A A A A A A A B B B A A/B A/B B B B A/B A A A A A/B A A/B A/B B B A/B A/B A/B A/B A/B A/B B A/B B B B B B B A/B B A A/B A/B B A/B B B B B B A/B A/B A/B

NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH

Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal

R.D. Deshpande et al. / Marine Chemistry 157 (2013) 144–161

155

Table 1 (continued) Sr no

Sample code

Collection date

Cruise code

Long °E

Lat °N

Salinity instrument

Salinity

δ18O (‰)

δD (‰)

d-excess (‰)

Identified group

Analyzing laboratory

603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677

UMC-21440 UMC-21441 UMC-21442 UMC-21660 UMC-21661 UMC-21662 UMC-21663 UMC-21664 UMC-21665 UMC-21666 UMC-21684 UMC-21403 UMC-21404 UMC-21405 UMC-21443 UMC-21444 UMC-21445 UMC-21667 UMC-21668 UMC-21669 UMC-21685 UMC-21686 UMC-21687 UMC-21446 UMC-21447 UMC-21691 UMC-21670 UMC-21671 UMC-21672 UMC-21688 UMC-21689 UMC-21690 UMC-21673 UMC-21674 UMC-21676 UMC-21675 UMC-21406 UMC-21407 UMC-21408 UMC-21409 UMC-21410 UMC-21411 UMC-21412 UMC-21413 UMC-21414 UMC-21415 UMC-21416 UMC-21417 UMC-21418 UMC-21419 UMC-21420 UMC-21421 UMC-21422 UMC-21423 UMC-21424 UMC-21425 UMC-21426 UMC-21427 UMC-21428 UMC-21429 UMC-21430 UMC-21431 UMC-21589 UMC-21590 UMC-21591 UMC-21592 UMC-21593 UMC-21594 UMC-21595 UMC-21596 UMC-21597 UMC-21598 UMC-21599 UMC-21432 UMC-21433

27-Oct-10 27-Oct-10 27-Oct-10 27-Oct-10 27-Oct-10 27-Oct-10 27-Oct-10 27-Oct-10 27-Oct-10 27-Oct-10 27-Oct-10 28-Oct-10 28-Oct-10 28-Oct-10 28-Oct-10 28-Oct-10 28-Oct-10 28-Oct-10 28-Oct-10 28-Oct-10 28-Oct-10 28-Oct-10 28-Oct-10 29-Oct-10 29-Oct-10 29-Oct-10 29-Oct-10 29-Oct-10 29-Oct-10 29-Oct-10 29-Oct-10 29-Oct-10 30-Oct-10 31-Oct-10 1-Nov-10 1-Nov-10 13-Nov-10 13-Nov-10 14-Nov-10 14-Nov-10 14-Nov-10 15-Nov-10 15-Nov-10 16-Nov-10 16-Nov-10 17-Nov-10 17-Nov-10 18-Nov-10 18-Nov-10 19-Nov-10 19-Nov-10 20-Nov-10 20-Nov-10 21-Nov-10 21-Nov-10 22-Nov-10 26-Nov-10 26-Nov-10 27-Nov-10 27-Nov-10 28-Nov-10 28-Nov-10 5-Dec-10 5-Dec-10 5-Dec-10 5-Dec-10 6-Dec-10 6-Dec-10 6-Dec-10 6-Dec-10 7-Dec-10 7-Dec-10 7-Dec-10 23-Dec-10 24-Dec-10

SG-C SG-C SG-C SPS-D SPS-D SPS-D SPS-D SPS-D SPS-D SPS-D SPS-E SG-A SG-A SG-A SG-C SG-C SG-C SPS-D SPS-D SPS-D SPS-E SPS-E SPS-E SG-C SG-C SPS-E SPS-D SPS-D SPS-D SPS-E SPS-E SPS-E SPS-D SPS-D SPS-D SPS-D SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SG-B SK-278 SK-278 SK-278 SK-278 SK-278 SK-278 SK-278 SK-278 SK-278 SK-278 SK-278 SG-C SG-C

73.24 73.32 73.64 74.72 74.90 75.08 75.24 75.43 75.62 75.79 74.81 73.67 73.77 73.82 73.73 73.73 73.77 75.95 76.10 76.27 73.97 73.32 74.48 73.73 73.68 76.49 76.75 77.07 74.15 74.33 73.88 73.75 77.41 77.70 78.10 78.30 73.19 72.90 72.78 72.65 72.53 72.45 72.75 73.13 73.30 73.04 73.15 72.88 72.58 72.49 72.50 72.81 73.05 72.96 73.00 73.38 72.83 72.55 72.68 72.78 72.95 73.32 77.48 77.27 76.80 76.30 75.55 75.33 75.00 74.70 74.25 74.07 73.93 74.18 74.12

14.32 14.59 14.76 12.56 12.18 11.67 11.41 10.99 10.56 10.17 12.26 14.75 14.98 15.09 14.85 15.14 15.16 9.82 9.47 9.25 12.60 13.60 13.14 15.17 15.40 8.72 8.40 8.09 14.52 14.15 14.89 15.15 7.88 7.92 8.20 8.71 15.60 15.36 15.67 16.07 16.26 16.44 16.58 16.58 16.36 16.58 16.77 17.00 17.33 17.37 17.67 17.76 17.40 16.80 16.40 15.96 16.02 16.28 15.99 15.90 15.72 15.64 7.43 7.90 8.28 8.73 10.27 10.88 11.35 11.95 13.23 13.73 14.20 12.99 12.92

Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Digi Auto Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Auto Sal Digi Auto Digi Auto

35.52 35.43 35.55 31.52 33.17 34.19 33.86 33.36 33.01 32.48 32.92 34.07 32.83 33.11 34.26 34.70 34.77 29.84 34.82 34.27 33.01 31.27 34.34 34.62 34.79 33.24 34.92 35.23 35.20 32.49 33.06 33.03 33.35 35.25 34.81 35.21 35.85 35.64 34.51 35.39 35.41 34.38 36.11 35.09 34.71 34.02 35.81 35.51 35.79 35.57 36.70 34.39 34.85 32.91 35.82 35.09 34.69 36.01 34.70 35.71 35.38 35.24 31.44 30.74 30.96 30.45 30.75 30.88 32.74 34.79 33.17 35.25 34.80 34.15 33.79

0.48 0.66 0.50 0.36 0.51 1.34 0.62 0.55 0.43 0.41 0.35 0.40 0.10 0.14 0.55 0.39 0.48 0.08 0.70 1.27 0.41 0.01 0.53 0.50 1.13 0.86 1.03 1.07 0.78 0.34 0.37 0.44 0.83 1.05 0.65 0.68 0.52 0.22 0.50 0.32 0.67 0.51 0.78 0.31 0.24 0.28 0.25 0.62 0.37 0.36 0.43 0.20 0.37 0.43 0.35 0.41 0.49 0.50 0.79 0.52 0.44 0.32 −0.10 −0.21 −0.09 −0.56 −0.12 −0.22 0.56 1.26 1.34 0.96 1.15 0.19 0.17

5.57 6.64 4.76 3.65 4.95 6.82 5.07 4.79 4.79 4.31 3.09 4.99 3.32 3.49 4.55 5.54 5.64 3.09 6.05 6.38 2.68 2.15 4.35 5.63 5.88 4.36 5.96 6.13 6.10 2.71 3.44 3.26 5.51 5.46 4.32 4.54 5.79 4.95 5.89 4.60 4.95 5.52 5.86 4.32 3.84 3.45 4.12 5.39 5.18 5.35 4.47 3.84 5.01 2.98 3.30 3.42 4.12 5.02 6.36 5.27 5.07 4.59 0.11 −1.13 −0.78 −1.54 −1.17 −0.26 4.06 6.45 4.53 6.06 6.06 3.00 2.23

1.77 1.37 0.75 0.77 0.84 −3.90 0.13 0.40 1.33 1.02 0.32 1.76 2.52 2.34 0.18 2.41 1.78 2.43 0.42 −3.76 −0.64 2.08 0.14 1.67 −3.16 −2.54 −2.31 −2.42 −0.13 −0.04 0.45 −0.24 −1.16 −2.94 −0.88 −0.88 1.60 3.20 1.88 2.07 −0.40 1.44 −0.40 1.82 1.89 1.22 2.15 0.42 2.26 2.46 1.06 2.22 2.06 −0.44 0.48 0.15 0.23 1.03 0.02 1.12 1.56 2.02 0.92 0.54 −0.08 2.91 −0.21 1.51 −0.39 −3.66 −6.16 −1.61 −3.12 1.50 0.83

A/B A A B A/B A A/B A/B B B B A/B B B A A/B A/B B A A B B A A/B A A/B A A A A/B B B A/B A A A A A/B A A/B A A A A/B A/B A/B A/B A A/B A/B A/B A/B A/B B A/B A/B A/B A/B A A A/B A/B B B B B B B A/B A A/B A A A/B B

NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH NIH

Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal Sal

Sal Sal

(continued on next page)

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Table 1 (continued) Sr no

Sample code

Collection date

Cruise code

Long °E

Lat °N

Salinity instrument

Salinity

678 679 680 681 682 683

UMC-21434 UMC-21435 UMC-21436 UMC-21437 UMC-21438 UMC-21439

24-Dec-10 25-Dec-10 25-Dec-10 26-Dec-10 26-Dec-10 26-Dec-10

SG-C SG-C SG-C SG-C SG-C SG-C

73.73 73.48 73.47 73.31 73.42 73.27

13.17 13.38 13.79 14.00 14.11 14.30

Digi Digi Digi Digi Digi Digi

33.41 33.47 34.69 34.47 34.43 35.46

Auto Auto Auto Auto Auto Auto

Sal Sal Sal Sal Sal Sal

δ18O (‰) 0.20 0.19 0.36 0.58 0.73 0.56

δD (‰)

d-excess (‰)

Identified group

Analyzing laboratory

1.56 1.44 3.48 5.18 5.92 6.64

0.00 −0.10 0.64 0.52 0.07 2.16

B B A/B A A A

NIH NIH NIH NIH NIH NIH

Abbreviations in cruise codes. SSM: Sagar Sampada; SK: Sagar Kanya; ABP: Acadamic Boris Petrov; MVK: M V Kavaratti; SPS: Sagar Paschimi; SG: M F V Sagarika; SM: Sagar Manjusha; SP: Sagar Purvi; SSK: Sagar Sukti. Abbreviations of Laboratory names: PRL: Physical Research Laboratory, Ahmedabad, India; NIH: National Institute of Hydrology, Roorkee, India. A and B refer to the identified Group A (S N 34 and δ18O N0.5‰) or Group B (S b 34 and δ18O b0.5‰); A/B refers to samples that can be placed in either of the two groups because of one or the other property as in Figs 4 and 5.

waters is significantly influenced by kinetic fractionation due to strong evaporation. It may be worth noting that the δ18O–δD relationship of the GOSWL of Rohling et al. (2007) was obtained for samples with δ18O b1.3‰ which correspond to S b38. The δ18O–δD relationship of GOSWL was seen to breakdown for samples with higher values of δ18O. In the case of the AS we see this breakdown in δ18O–δD relationship occurring for samples with δ18O N 0.5‰ and S N 34. This breakdown is due to intense evaporation leading to kinetic isotope fractionation as is evident from the d-excess–δ18O plot (Fig. 5b). Similar inferences can also be drawn from d-excess–δ18O plot for global ocean data set (http://data.giss. nasa.gov/o18data/) suggesting that identification of areas of high net evaporation in the world oceans may be more rigorously done using d-excess parameter. This is because even a small admixture of continental runoff (d-excess ~10‰) and/or equilibrium evaporation (at Rh = 100%) of seawater can raise the d-excess of resulting water to N 0‰. However, it is only through kinetic fractionation during evaporation that lower (b 0‰) values of d-excess can result. We have arbitrarily chosen 0.5‰ as an indicative cutoff value above which the sea water may contain continental runoff, unaffected by significant kinetic evaporation. Since the continental runoff into the AS from the Indian landmass is highly seasonal, the dilution effects due to this can best be studied by examining the seasonal variation in the isotope-salinity distributions/ relationships. The geographical distribution of isotope and salinity data from coastal stations, in the AS, for different seasons, is shown in

Fig. 2. Arabian Sea water sampling locations for this study (all samples collected during August 2008 to December, 2010). The dashed outline indicates the limits of the broad area covered in this study. Abbreviations are: Mm = Mumbai; Dp = Dapoli; Mn = Mangalore; Kk = Kozhikode; Th = Thiruvananthapuram.

Figs. 6, 7 and 8 respectively for the months of Mar–May (pre-monsoon), Jun–Oct (monsoon) and Nov–Feb (post-monsoon). The summary statistics for δ18O–S and δ18O–δD regressions are presented in Table 3 and are discussed below. The sampling locations, the δ18O and salinity in the AS near the west coast of India, during the months of March–May (2008 to 2010), are shown in Fig. 6a, b and c respectively. Both the isotope and the salinity data indicate that in this season, relatively high salinity waters (S N 34) extend almost up to the west coast of India. These waters also show high δ18O values (N0.5‰) and do not show any significant δ18O– δD relationship (Fig. 6d). The d-excess–δ18O plot shows a decreasing trend in the d-excess with increasing δ18O (Fig. 6e), clearly indicating kinetic evaporation effect during this season even in the coastal waters. In spite of a large scatter seen in the δ18O–S plot (Fig. 6f), the F statistics

Fig. 3. Contour plots of δ18O (top) and salinity (bottom) for all samples forming part of this study. Note a very narrow range of variation observed in much of the Arabian Sea except near the west coast of India. The averages are area weighted mean values.

R.D. Deshpande et al. / Marine Chemistry 157 (2013) 144–161

157

Fig. 4. A weak relationship exists between (a) δ18O–S and (b) d-excess–S for samples with S b34, though general geographical correspondence between δ18O and S is seen in Figure 3. It seems from the two plots that the surface waters of the AS can be separated into two groups, namely Group A (largely open ocean samples) and Group B (largely coastal samples). The samples in Group B (S b34) have relatively less scatter and narrower range of δ18O compared to samples in Group A.

is significant (p b 0.001). The relatively high values of salinity (N 34) and δ18O (N0.5‰) in the coastal waters during March–May (pre-monsoon season) may be due to the spreading of high salinity water (ASHSW), in addition to negligible continental discharge from the Indian landmass during this pre-monsoon season.

Table 2 Amount weighted average δ18O values rainwater from few selected locations along the west coast of India. Based on unpublished data of the National Programme on Isotope Fingerprinting of Waters of India (IWIN). http://www.prl.res.in/~iwinoffice/. Station

Month

Amount weighted average δ18O (‰)

Mumbai 18.98°N 72.83°E

Mar–May Jun–Oct Nov–Feb Annual Mar–May Jun–Sep Nov Annual Mar–May Jun–Oct Nov–Feb Annual Mar–May Jun–Oct Nov–Feb Annual Mar–May Jun–Oct Nov–Feb Annual

−0.23 −2.44 −5.34 −2.53 – −2.75 −8.30 −2.75 −0.23 −2.44 −5.34 −2.67 −1.55 −3.53 −9.07 −4.04 −2.77 −4.04 −6.80 −5.09

Dapoli 17.76°N 73.19°E

Mangalore 12.87°N 74.88°E

Kozhikode 11.25°N 75.77°E

Thiruvanan-thapuram 8.49°N 76.95°E

Note: Mumbai, Dapoli and Mangalore essentially receive rainfall from SW summer monsoon. Kozhikode and Thiruvanantha puram also receive rainfall from NE winter monsoon.

Fig. 5. (a) The δ18O–δD regression line for surface water samples collected from the Arabian Sea. There is only a poor linear correlation between the two parameters considering all the samples collected from the Arabian Sea. Similar to isotope-salinity plots (Figure 4) the surface waters of the AS can be separated into two groups, namely Group A (largely open ocean samples) and Group B (largely coastal samples). (b) The d-excess–δ18O plot for the same samples show a progressive decrease in d-excess values with increasing δ18O indicating significant kinetic fractionation due to strong evaporation for samples of Group A.

The sampling locations, the δ18O and salinity, during the months of Jun–Oct (SW monsoon season), are shown in Fig. 7a, b and c respectively. Most samples belong to the west coastal region of south India (between 6° and 14°N). Even during this season with heavy rainfall and resultant runoff draining the Western Ghats, there is only a very narrow coastal zone having water with S b 34 and δ18O b 0.5‰. Consequently, the δ18O–δD regression (Fig. 7d) with all samples (N = 55) has a very low slope and intercept. Alternatively, it may be possible to draw two regression lines separately, as in Fig. 5. The d-excess–δ18O plot (Fig. 7e), as in March–May season, shows a decreasing trend of d-excess with increasing δ18O, for samples with δ18O N0.5‰, indicating that, even fairly close to the west coast of India, kinetic evaporation effects are significant during the monsoon season also. The δ18O–S plot (Fig. 7f) also shows considerable scatter, a pattern similar to March–May season. The sampling locations, the δ18O and S, during the post-monsoon season (Nov–Feb), are shown in Fig. 8a, b and c respectively. In this case the samples are distributed almost along the entire west coast of India, but the zone with salinity b 34 and δ18O b0.5‰, as in previous two seasons is extremely narrow. This is expected in view of the fact that even during the monsoon season the fresh water zone in the AS along the west coast of India is very narrow. The δ18O–δD (Fig. 8d), d-excess–δ18O (Figure 8e) and δ18O–S (Figure 8f) plots show similar pattern as in the previous two seasons.

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Fig. 6. Geographical distribution of sampling locations (a), δ18O (b) and S (c) in the Arabian Sea, near the west coast of India, during the months of March–May (2008 to 2010). Relatively high salinity (S N33) waters extend all the way up to the west coast of India. These waters also show high δ18O values (N0.3‰) and a large scatter in δ18O–δD (d) and δ18O–S plots. The dexcess–δ18O plot shows a trend of decreasing d-excess with increasing δ18O.

It is, thus, evident from the above that the dilution effect dominates the isotope-salinity and δ18O–δD relationships only in a very narrow zone along the west coast of India, even during the SW monsoon season. In contrast, evaporation dominates most of the AS, throughout the year, and the high salinity of the AS is further supplemented by the movement of ASHSW mass from northern and western AS.

3.2. Temporal variation With a view to examine the effect of large scale ocean currents (namely, WMC, EC, SMC and SECC between the eastern and western north Indian Ocean; see Fig. 1), on salinity and isotopes, samples were collected along six profiles going across 0° to ~10°N latitude and along

Fig. 7. The same as Fig. 6 but for the months of June–October (2008–2010). During this season (Jun–Oct) the extent of the seaward spread of fresh water runoff is the minimum even though the runoff flux is the highest. This is possibly due to the wind driven forcing of open seawater towards coastal India and the prevalent summer monsoon current (SMC) in the ocean. This also accounts for the observed relatively high gradient of salinity and isotope.

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159

Fig. 8. Same as Fig. 6 but for the months of November to February (2008–2010). Low δ18O water mass is seen close to the west coast of India even though the freshwater influx due to west flowing rivers of India is much smaller during winter months of Nov–February compared to summer months of Jun–October. The causative factor for this is likely to be the winter-time surface-advection of less saline and low δ18O water mass from the BOB, as in the case of March to May (Fig. 6). See Fig. 1 for the ocean currents.

~65°E and ~82°E longitude, during different months between June to December. The latitudinal distribution of S, δ18O and δD for selected cruises undertaken during various years are shown in Figs 9, 10 and 11. For each of these latitudinal profiles the sampling locations with respect to the southern coast of India are also shown in the inset of each figure. In the following discussion the focus is on the month of sample collection, irrespective of the year. This is because the broad patterns of the ocean circulations are known to repeat annually. Fig. 9a shows profile along 65°E for the month of June, 2010. A dip in all three parameters (S, δ18O and δD) between the latitudes 1°–5°N suggests the influence of the EC (Fig. 1a and b) bringing low salinity and isotopically light water from eastern part of the north Indian Ocean. The observed increase in the three parameters pole-ward of 5°N is possibly related to the SMC (Fig. 1b) bringing high salinity and isotopically heavier water from the Somalia coast. Fig. 9b shows a profile around 75°E for the month of July, 2010. At this time and location of the EC seems to have moved slightly northwards resulting in a decreasing trend in isotopic composition from 2° to 7°N due to movement of isotopically lighter water from the southern BOB with roughly the same salinity as the AS during this period (Achyuthan et al., 2013). This may account for only small perturbations observed in the salinity profile

(Fig. 9b). The northward increase in all the three parameters from ~7°N could be related to the SMC and WICC (Fig. 1b). Fig. 10a (profile between 75° and 82°E) shows a low between 2° and 3°N in both S and δ18O, during the month of October, 2008. This low is connected to the EC, with farther northward increase related to the SMC. Broadly a similar picture between 2° and 4°N is seen in November (Fig. 10b) for the profile along 65°E, with a low related to the EC and high related to the SMC. The broad picture emerging from Fig. 11a for December, 2008 is similar to that for the November, 2009 (Fig. 10b) from roughly the same location. This similarity is in terms of the lower values of both salinity and isotope due to the EC between 2° and 4°N, followed by high values farther north due to the SMC. The profile in December, 2009 between 68° and 72°E (Fig. 11b) also shows the lowering effect in salinity and isotope parameter due to the EC followed by increasing trend due to the SMC, up to about 9°N, followed by a slight decrease between 10° and 12°N. A similar decrease around 10°N was also seen in profiles for November, 2009 (Fig. 10b). In both these cases the slight decrease in isotopic and salinity parameters may indicate an influence of winter WICC even at a distance considerably away from the coast. From the observed patterns in the monthly profiles (Figs. 9, 10 and 11) as discussed above, it is clear that, in general, latitudinal variations

Table 3 Summary of regression statistics between salinity and isotope data of the Arabian Sea surface water samples from coastal India. Regression equation: δ18O = m × S + c1 Sr. no.

Number of samples

Slope (m) ± std. error

Intercept(c1) ± Std. error

All Arabian Sea samples 2008–2010 1 682 0.14 ± 0.01 −4.31 ± 0.33 Off the west coast of India: March–May (2008–2010) 2 94 0.20 ± 0.04 −6.15 ± 1.43 Off the west coast of India: June–October (2008–2010) 3 135 0.10 ± 0.02 −2.70 ± 0.55 Off the west coast of India: November–February (2008–2010) 4 135 0.18 ± 0.02 −5.59 ± 0.65

Regression equation: δD = m × δ18O + c2 2

R

p

Ref.

Number of samples

Slope (m) ± std. error

Intercept (c2) ± Std. error

R2

p

Ref.

0.25

b0.001

Fig. 4a

335

3.20 ± 0.16

3.10 ± 0.14

0.55

b0.001

Fig. 5a

0.20

b0.001

Fig. 6e

43

0.54 ± 0.59

5.91 ± 0.58

0.02

0.36

Fig. 6d

0.22

b0.001

Fig. 7e

55

3.34 ± 0.33

2.64 ± 0.24

0.66

b0.001

Fig. 7d

0.40

b0.001

Fig. 8e

63

3.72 ± 0.48

2.51 ± 0.27

0.50

b0.001

Fig.8d.

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Fig. 9. Latitudinal variation in the salinity, δ18O and δD for the months of (a) June, 2010 and (b) July, 2010. The inset shows the sampling locations with respect to the southern tip of India for the respective sampling period.

in isotopic composition and salinity of the surface waters of the AS are opposite to that observed in the BOB (Achyuthan et al., 2013) where salinity and isotopic composition show a general decreasing trend from south to north. It may be recalled that salinity and isotopic composition in the surface waters in the BOB are generally governed by heavy continental runoff into the northern BOB and its southward dispersal (Achyuthan et al., 2013). The reverse trend in variation of salinity and

Fig. 11. The same as Fig. 9 but for the months of December, 2008 and 2009.

isotope in the AS on the other hand could be due to high evaporation manifested by very low d-excess values in the northern AS. The various profiles indicate that the influence of the EC is more definitively visible in the isotopic variation than in the salinity. This is possibly due to the eastern sector of the northern Indian Ocean having nearly similar salinity values (relatively low contrast) but lighter isotopic values (relatively higher contrast) compared to the western sector. The contrast between the chemical and isotopic properties of the two sectors of the northern Indian Ocean is maintained by the movement of the water through the zonal ocean current EC. It is also noticed that the effect of the EC is visible between 0° and 5°N with seasonal migrations of the order of 1° to 2°. The signatures of the WICC, both in summer and winter, are seen not only in the coastal waters but also noticeable even at a considerable distance from the west coast of India.

3.3. Summary and conclusion

Fig. 10. The same as Fig. 9 but for the months of (a) October, 2008 and (b) November, 2009.

Results of isotopic (δ18O and δD) and salinity (S) analyses of 683 surface water samples of the AS, collected during 2008–2011, are reported. Salient observations are: (1) the δ18O and S parameters exhibit some geographical correspondence with significant correlation for samples along coastal regions, i.e. salinity b 34; (2) the belt of relatively freshwater (lower S and δ18O) along the west coast of India is narrowest during the summer monsoon season even though river discharge is relatively higher which, however, requires corroboration with more data over an extended period; (3) the δ18O–δD regression line for coastal samples has a slope similar to the global ocean surface water line (GOSWL) (4) this liner relationship between δ18O and δD breaks down completely in the months of March–May even for coastal stations; (5) for open ocean stations, the δ18O–δD regression shows considerable scatter and much lower slope; (6) the δ18O–δD and the d-excess–δ18O relationships indicate strong kinetic fractionation due to evaporation from surface water throughout the year, with enhancement in summer months; (7) contrary to the adjoining BOB, both δ18O and S, in general, show an increasing trend from 0° to 10°N; (8) values of d-excess b 0.5‰ may be taken as an indicator of regions dominated by high net evaporation in world oceans.

R.D. Deshpande et al. / Marine Chemistry 157 (2013) 144–161

Acknowledgment The work reported here has been carried out under the aegis of a National Programme on Isotope fingerprinting of Waters of India (IWIN), funded jointly by the Department of Science and Technology, Govt. of India vide grant no. IR/S4/ESF-05/2004, and the Physical Research Laboratory (PRL). The authors thank the two anonymous reviewers for their critical comments and valuable suggestions which helped improve the manuscript. The authors also thank the Fishery Survey of India (FSI), National Centre for Antarctic and Ocean Research (NCAOR), National Institute of Ocean Technology (NIOT), the Director, National Institute of Oceanography (NIO) for providing logistic support and assistance during sample collection.

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