Hydrogen peroxide at the Bermuda Atlantic Time Series Station: Temporal variability of seawater hydrogen peroxide

Marine Chemistry 97 (2005) 236 – 244 www.elsevier.com/locate/marchem

Hydrogen peroxide at the Bermuda Atlantic Time Series Station: Temporal variability of seawater hydrogen peroxide G. Brooks Avery Jr.*, William J. Cooper, Robert J. Kieber, Joan D. Willey Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, North Carolina 28403-5932, United States Received 14 May 2004; received in revised form 25 February 2005; accepted 25 March 2005 Available online 14 July 2005

Abstract Hydrogen peroxide concentrations, production rates and decomposition rates were measured during each of two 3-week cruises in August 1999 and March 2000 at the Bermuda Atlantic Time Series Station. Patterns of variation in the concentrations of hydrogen peroxide in surface seawater at BATS were drastically different in August of 1999 compared with March of 2000. In August, hydrogen peroxide concentrations were primarily controlled by input from rain, whereas in March, they were controlled by photochemical processes and showed diurnal variations. The highest concentrations in surface water in August followed rain events, whereas in March, they occurred at approximately 1400 after rapid photochemical production. This production in March was followed by an equally rapid loss of H2O2, probably driven by a secondary photochemical process, then by much slower decline at night. The combination of photochemical production and consumption processes resulted in a steady-state system over a 24-h period in March but not August. The dark decomposition of surface water hydrogen peroxide incubated in storage experiments was the same during both August and March and followed first order kinetics with a rate constant of 0.009 h 1. This was in remarkably good agreement with the decay of the atmospheric hydrogen peroxide signal in surface seawater observed in August. The comparable rate constant for deep water from 200 m was about one-third of that for BATS surface seawater in March. Because filtered seawater had lower production rates than unfiltered seawater from the same depth, biological production may contribute to surface seawater hydrogen peroxide at BATS during the March spring plankton bloom, but it is not the dominant source. D 2005 Elsevier B.V. All rights reserved. Keywords: Hydrogen peroxide; Seawater; Temporal variability

1. Introduction

* Corresponding author. Tel.: +1 910 962 7388; fax: +1 910 962 3013. E-mail address: [email protected] (G.B. Avery). 0304-4203/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.marchem.2005.03.006

Hydrogen peroxide (H2O2) is a chemically labile oxidant that plays a central role in a variety of important biogeochemical processes occurring within seawater including reactions with a number of highly

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reactive free radicals and trace metals. There are several potential sources that deliver hydrogen peroxide to surface seawater, the most thoroughly studied of which is photochemical production (e.g., Cooper and Zika, 1983; Cooper et al., 1988, 1989; Micinski et al., 1993; Petasne and Zika, 1987, 1997; Zafiriou, 1983; Zika, 1981). Another potentially important, albeit more episodic, source of H2O2 in the open ocean is wet deposition (Cooper et al., 1987; Miller and Kester, 1994, Hanson et al., 2001; Kieber et al., 2001; Yuan and Shiller, 2000). Dry deposition is another possible source of H2O2 in surface seawater, especially in very low H2O2 waters such as the Weddell and Scotia Seas in the Southern Ocean (Kieber et al., 2001; Thompson and Zafiriou, 1983, Yocis et al., 2000). Biological processes are a fourth source of H2O2 (Collen et al., 1995; Stevens et al., 1973; Palenik and Morel, 1988; 1990a,b; Palenik et al., 1987, 1989; Patterson and Myers, 1973; Roncel et al., 1989; Roulier et al., 1990). Potential loss processes of H2O2 in seawater include microbially mediated enzymatic reactions (Cooper and Zepp, 1990; Moffett and Zafiriou, 1990, 1993; Zepp et al., 1987) and direct photochemical loss (Yocis et al., 2000). While there have been several studies attesting to the potential for each of these processes to play a role in the distribution of hydrogen peroxide in the sea, the relative importance of these production and decay processes taken together in the open ocean remains unclear. The goal of this project, therefore, was to quantify production and decay rates of hydrogen peroxide in a single water mass over an extended period of time during two distinctly different seasons at the Bermuda Atlantic Time Series Station (BATS). This study is unique because all potential controls of seawater H2O2 concentration were evaluated together including atmospheric deposition, photochemical production and decay as well as biological production and decay. This study is also unique in that these processes were studied in a single water mass over time periods of weeks during two distinctly different seasons. Following a single water mass for such long periods was important because it allowed us to measure changes caused by in situ processes rather than movement into different water masses. In addition to field measurements, production and decomposition rates were determined in controlled laboratory experiments which were then compared directly with field

237

observations. Studying the same site during early spring and late summer also made it possible to assess the importance of seasonal shifts in atmospheric and water column conditions on the rates of peroxide production and decay processes.

2. Methods 2.1. Sampling Samples were collected during August 1999 and March 2000 aboard the R.V. Endeavor in the vicinity of the Bermuda Atlantic Time Series Station (BATS). Samples for seawater hydrogen peroxide profiles were obtained with the ship’s 24 bottle rosette sampler using 10-L Niskin bottles. The surface peroxide time series was done with surface water collected via a clean polyethelene bucket deployed over the side of the ship. A drogue buoy (drifter) was deployed and followed by the ship to assure that the ship remained in the same water mass throughout the sampling program. 2.2. Hydrogen peroxide Hydrogen peroxide was analyzed by a fluorescence decay technique involving the peroxidase mediated oxidation of the fluorophore scopoletin by H2O2 in a phosphate-buffered (0.1 M) sample at pH 7 (Kieber and Helz, 1986, 1995). Calibration curves were obtained by recording the decrease in fluorescence upon addition of hydrogen peroxide spikes to the sample. Fisher Scientific 30% ACS reagent grade H2O2 without a stabilizer was used for spikes. The method has an analytical precision of 2% RSD at ambient surface seawater concentrations of approximately 100 nM with a detection limit of 2  10 9 M. Hydrogen peroxide was also determined by a chemiluminescent method involving reaction of hydrogen peroxide with an acridinium ester 10-methyl-9-( pformylphenyl)-acridinium carboxylate trifluoromethanesulfonate. For the chemiluminescent method, 800 AL of sample was added to a polypropylene vial, followed by addition of a pH 10 borate buffer (100 AL) and, after the lid was closed, addition of 20 AL of 1  10 6 M acridinium ester using the auto-injection system. The method has an analytical precision of 4% RSD at typical surface and atmospheric water con-

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centrations with a detection limit of 5 nM (Cooper et al., 2000). An intercalibration between these two methods was conducted in order to verify the accuracy of the hydrogen peroxide results obtained for seawater at BATS. In all cases the disparity between analytical results was less than a few percent which is well within analytical uncertainty with no statistically significant difference between results (Kieber et al., 2001). 2.3. Optical buoy experiments Water samples were deployed in 250-mL quartz round bottom flasks in an array at preset depths for all photochemical formation measurements (Kieber et al., 1997). The system provided for near-surface irradiations and was free floating away from the ship. It was deployed prior to sunrise and retrieved after sunset. Net hydrogen peroxide photochemical formation rates were determined from the difference in concentration between light exposed and dark controls divided by exposure time. Two samples were filtered (to determine biological effects) by pressurizing a 30-L Go Flo to 5 psi and passing the water through a 0.2 Am polycarbonate filter. 2.4. Decay rates Decay rates were calculated for unfiltered seawater as the difference between initial and final concentrations after dark storage at room temperature. The decay rate of hydrogen peroxide in surface seawater resulting from rainwater addition was also determined by following the decline in surface peroxide concentrations several days after the cessation of the rain event.

3. Results and discussion 3.1. Variations in surface H2O2 concentrations Surface water concentrations of hydrogen peroxide collected on the August 1999 cruise illustrate the dramatic effect of rain on surface seawater concentrations (Fig. 1). Each data point in Fig. 1 represents surface seawater hydrogen peroxide concentrations at various times over approximately 1 week. There were

40 µM rain input

250

57 µM rain input

200

H2O2 (nM)

238

150 100 50 0 0

50

100

150

200

Time (hrs) Fig. 1. BATS surface seawater hydrogen peroxide concentrations from 0900 August 7, 1999 to 0900 August 15, 1999. The vertical arrows indicate the times of rain events during this time period. The first event was a 1.3-cm rain event with 40 AM H2O2 that occurred over 24 h prior to sampling. The second was a brief 2-mm rain with 57 AM H2O2.

significant rain events on August 7th (T = 0 h) and August 12th (T = 20 h) where seawater concentrations were highest. In the absence of significant rainfall after the 7th, the surface seawater concentration of hydrogen peroxide at BATS steadily decreased until the next influx of rainwater peroxide on the 12th. Input by rain overwhelmed photochemical or biological production during this time period. The dramatic impact of rain was apparent even though only 4.6 cm total of rain was received on this cruise versus 8.9 cm average for the 3 weeks in August (Bermuda Weather Service data). This was a very calm cruise, so hydrogen peroxide concentrations remained relatively high in surface seawater well after cessation of rain events due to limited vertical mixing. Although there was no time when surface water was not influenced by rain on this cruise, we estimate a concentration of approximately 80 nM for surface seawater without rain impact in August. The majority of H2O2 concentrations were greater than 100 nM similar to the concentrations of H2O2 determined for the Sargasso Sea by Miller and Kester (1994) during a cruise also influenced by rainwater. Because rain dominated the sampling period of this first cruise, photochemically induced diurnal variations were not observed in surface seawater hydrogen peroxide concentrations, and the system never achieved steady-state peroxide concentrations. Conditions were drastically different during the March cruise, when only 1.7 cm of rain fell during the 3-week cruise versus 7.5 cm average at BATS (Bermuda Weather Service data). This provided a unique opportunity for observation of surface water

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H2O2 concentration variations driven solely by in situ photochemical and biological production and decomposition without external input from rain. To our knowledge, these are the first measurements of H2O2 surface water photochemical cycling over a multiple-day period in the same oligotrophic marine water mass. Surface water samples were collected every 2 h over a 5-day period during the March 2000 cruise during this period of minimal rainfall. The early morning concentration was approximately 30 nM. This concentration is lower than the dawn surface water concentration in August because of greater rain input in August in addition to elevated gas phase concentration of hydrogen peroxide in August (Kieber et al., 2001). A distinct diurnal pattern of H2O2 concentrations in surface water was observed in March with peak concentrations of approximately 70 nM occurring at mid-day (Fig. 2). The 40 nM diurnal change in H2O2 concentrations was the same as that observed by Miller and Kester (1994) in the Sargasso Sea indicating that these variations are typical of this location. The maximum concentration was observed at approximately 1400 h local time suggesting photochemical formation was primarily responsible for production of H2O2. Formation rates of H2O2 between early morning and approximately 1400 averaged 6.6 F 1.8 nM h 1 in surface water (Table 1a). This rate is similar to those reported by Obernosterer et al. (2000) of 5.5 nM h 1 and Yuan and Shiller 90 80

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Table 1a H2O2 production rates during peak photochemical production calculated from surface concentration data Date

Initial time (local)

Initial conc. (nM)

Final time (local)

Final conc. (nM)

Rate (nM/h)

3/22/00 3/23/00 3/24/00 3/25/00 3/26/00 Average

900 700 600 700 700

36.6 27.0 54.2 24.8 25.0

1400 1400 1400 1400 1300

83.5 74.4 72.2 62.4 64.4

9.4 6.8 2.2 5.4 6.6 6.6 F 1.8

Rates were calculated using initial and final concentrations and time.

(2001) of 8.3 nM h 1 for surface Atlantic waters at similar latitudes. The seawater maximum at 1400 h was much earlier in the day than the gas phase maximum, which occurred around 1800, or the rainwater maximum, which occurred during the 1800– 2400 time interval (Kieber et al., 2001). After the mid-day maximum was reached in late afternoon, concentrations of H2O2 decreased rapidly (7.4 F 2.6 nM h 1) at a rate comparable in magnitude to the rapid rates of H2O2 production observed earlier in the day (Table 1b). During the night, the rate of decrease in H2O2 concentrations slowed dramatically (Fig. 2). The rapid loss of peroxide before sunset suggests that photochemical processes are also involved in peroxide decomposition at BATS. Part of this photochemical loss mechanism could include direct photochemical decomposition of H2O2 similar to what was observed by Yocis et al. (2000). The authors observed an apparent photochemical decay of 1.0 to 1.2 nM h 1, or 50% of the production rate, in Ant-

H2O2 (nM)

70

Table 1b H2O2 consumption rates during peak photochemical consumption calculated from surface concentration data

60 50

Date

Initial time (local)

Initial conc. (nM)

Final time (local)

Final conc. (nM)

Rate (nM/h)

3/22/00 3/23/00 3/24/00 3/25/00 3/26/00 Average

1400 1400 1400 1400 1300

83.5 74.4 72.2 62.4 64.4

2100 2200 2000 1600 1600

26.7 31.6 44.0 39.7 41.9

8.1 5.4 4.7 11.4 7.5 7.4 F 2.6

40 30 20 24

12

24

12

24

12

24

12

24

12

24

Local Time Fig. 2. BATS surface seawater hydrogen peroxide concentrations from 0900 March 26, 2000 to 2200 March 26, 2000. Light and dark intervals are shown, with light defined as 0600–1800.

Rates were calculated using initial and final concentrations and time.

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Table 2 Apparent net H2O2 production rate between dawn and dusk Date

H2O2 concentration at dawn (nM)

H2O2 concentration at dusk

Elapsed time (h)

H2O2 production rate (nM/h)

3/22/00 3/23/00 3/24/00 3/25/00 3/26/00 Average

36.6 27.0 46.5 24.8 25.0

47.7 39.5 56.4 45.2 47.3

10 10 12 10 11

1.1 1.3 0.8 2.0 2.0 1.4 F 0.5

face water production rates would have to be lower than the incubation production rates. One important consequence of the similarity of production and decay rates observed in March (Fig. 2) was that the high and low concentrations of hydrogen peroxide were similar over time periods of days. This consistent pattern of variation in hydrogen peroxide concentrations was never observed during the August cruise because of elevated atmospheric inputs. 3.2. Photochemical H2O2 production

H2O2 consumption rate from 24-h dark incubation experiments Sample depth (m)

Initial conc. (nM)

Final conc. (nM)

H2O2 consumption rate (nM/h)

5 40 200 Average

121 117 112

82.4 82.2 83.3

1.6 1.5 1.2 1.4 F 0.2

Optical buoy experiments were deployed from dawn until dusk to measure photochemical production of H2O2 as a function of depth in the absence of other variables such as vertical mixing. The difference between light and dark controls was defined as photochemical production. These experiments measured net daytime formation rates of H2O2 since surface seawater concentrations of H2O2 peak and then decrease during daylight hours rather than continually increase during this dawn to dusk period (Fig. 2; Table 2). Photochemical production was greatest in the top 2 m and was very small or negligible by 30 m in both seasons (Table 3). Rates of photochemical production were very similar in August and March in the optical buoys indicating photochemical production processes were very similar during these two different sampling periods despite the differences in solar intensity. Hydrogen peroxide depth profiles obtained at dawn, 1400 and 1900 on March 27, 2000, indicate the net in situ rate of production between dawn and 1900 was

arctic waters during the austral spring (Yocis et al., 2000). It is also possible that part of the photochemical loss could result from production of a photochemically produced H2O2 sink during the day such as Fe(II)(aq) which would become depleted during the night. Mixing was a relatively unimportant factor controlling surface H2O2 concentrations for two reasons: (1) peroxide concentrations remained constant after sunset (Fig 2). If mixing was important, the concentration of H2O2 would continue to decrease throughout the night. (2) Production rates in optical buoys matched those in the surface water. If mixing was an important parameter controlling peroxide distributions, the sur-

Table 3 Net hydrogen peroxide formation rates (formation minus decay) in nM h 1 for BATS seawater samples collected from the depth indicated and irradiated by sunlight in quartz flasks at depths up to 30 m for 12 h (0800 to 2000 h) Buoy depth (m)

09/08/99 446 W m 8m

b1 1 2 5 10 30

3.4 4.0 3.1 1.4 0.8 NA

2

11/08/99 NA 8m

15/08/99 422 W m 40 m

2.7 NA 2.5 3.4 2.4 NA

1.3 NA NA 1.0 0.8 0.2

2

24/03/00 376 W m 20 m 5.0 3.6 3.1 2.3 1.2 1.4

2

26/03/00 529 W m 20 m 3.3 3.1 3.1 2.3 1.2 1.0

2

27/03/00 413 W m 20 m 3.1 2.2 1.3 0.3 0.6 0.3

2

27/03/00 369W m 20 m

2

1.5 0.5 0.2 0.2 0.1 NA

Solar sea surface irradiance data (W m 2) is the average for the time of deployment. NA—not analyzed. The two samples from 27 March 2000 were filtered (pore size 0.20-Am pore size) before irradiation; all others were unfiltered. Seawater hydrogen peroxide concentrations varied from 1 to 200 nM after irradiation.

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approximately 2 nM h 1 over the top 20 m (Fig. 3) comparable to the rates determined from the incubated buoy experiments (Table 3). Hydrogen peroxide photochemical production rates were all significantly lower in 0.2 Am filtered seawater samples relative to unfiltered samples at all depths (Table 3). Lower production rates in filtered samples suggest that at least part of the peroxide production in the optical buoys was biologically driven which is consistent with earlier peroxide production studies (Collen et al., 1995; Stevens et al., 1973; Palenik and Morel, 1988, 1990a,b; Palenik et al., 1987, 1989; Patterson and Myers, 1973; Roncel et al., 1989; Roulier et al., 1990). Although biological production was most likely occurring during these March irradiations, it is clearly not the dominant source of hydrogen peroxide at BATS during this time period (Table 3 and Fig. 4).

241 H2O2 (nM)

0

20

40

60

80

0

5

10

Depth 15 (m)

20

25

30

3.3. H2O2 decomposition Rates of dark H2O2 consumption were determined on incubated samples for one sample with six replicates in August and three samples collected at different depths in March (Table 4). Initial concentrations of H2O2 in the dark incubation experiments were adjusted to make them similar to peak concentrations observed in surface samples in order to eliminate any possible kinetic effect resulting from differences in H2O2 (nM) 0

20

40

60

80

Fig. 4. Hydrogen peroxide concentrations in seawater irradiated by sunlight in quartz flasks for a day at the depths indicated in March 2000. The seawater initially came from 20 m. Two water samples were unfiltered (X) and (E) and two were filtered (0.45 Am) to reduce biological activity prior to irradiation (n) and (x).

initial H2O2 concentrations. In August, this was done by irradiation with sunlight and in March by addition of hydrogen peroxide. Table 4 Decay of hydrogen peroxide in BATS seawater

0

Rate

20

nM h

40 60 80 Depth 100 (m) 120 140 160 180 200

Fig. 3. H2O2 depth profiles on March 26, 2000, dawn (x), 1400 h (n) and dusk (E). There was a brief squall with a trace of rain containing 11 AM H2O2 immediately prior to the dawn profile on this day.

August 8 m Std. Dev. March 5 m March 40 m March 200 m

0.78 0.13 0.69 0.64 0.34

Rate constant 1

h

1

0.0093 0.0017 0.0086 0.0075 0.0031

T 1/2 h 76 16 81 92 224

Each sample had hydrogen peroxide added to produce a starting concentration of approximately 120 nM. Hydrogen peroxide was measured seven times during dark room temperature storage for 144 h. Final concentrations varied from 25 to 74 nM in all experiments. The first order rate constant and half life are also given. Six replicates were done in August of 1999 using seawater from 8 m. These samples were irradiated at different depths prior to storage so starting concentrations varied from 127 to 193 nM; five measurements were made during the 150-h dark room temperature storage. Seawater from three different depths was used in the March 2000 experiments.

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ln [H2O2] (nM)

6

5

surface 8m 5m 40m 200m

4

3 0

50

100

storage experiments for the three shallowest samples (Table 4). Another important conclusion can be drawn from the data presented in Table 4 regarding the impact of depth on the decomposition rate of hydrogen peroxide in BATS seawater. The rate of decomposition was approximately half as fast at 200 m relative to what it was at the three shallower depths, even though initial concentrations were the same (Fig. 5). The difference in decay rates between samples collected at different depths may result from variations in the rate of biological decay. It may also result from the presence of some relatively long lived photochemically produced peroxide sink in the surface samples stored in the dark which would not be present in the deeper samples.

150

Time (hrs) Fig. 5. Ln [H2O2] in nM versus time in hours for the surface seawater in August (in Fig. 1) and the data in Table 4 for the decomposition of hydrogen peroxide. The top solid line is the regression line for the surface seawater samples collected for Fig. 1 and for the dark storage experiment in Table 4. The lower solid line is the regression line for the dark storage experiment with March 2000 seawater from 5 m and 40 m (Table 4). The dashed line is the regression line for the dark storage experiment with 200 m water collected in March 2000, which clearly has a different slope than the rest of the data. The slopes of the lines give the first order rate constants which are given in Table 4. Each regression line is significant ( p b 0.001).

3.4. Depth profiles The concentration of hydrogen peroxide was higher in surface relative to deep waters during both seasons, with a surface concentration of approximately 40 nM in March and 80 nM in August (Fig. 6). The mixed layer depth was approximately 25 m in August and 40 m in March, which reflects the higher, gale-force winds encountered for most of the March cruise. The concentrations became approximately the H2O2 (nM)

Rates of H2O2 consumption in incubated dark samples (Table 4) were much lower (b 1 nM h 1) compared to the rates of in situ H2O2 loss observed in surface seawater during the late afternoon (7.4 nM h 1; Table 1b) supporting the idea that the rapid rates of H2O2 consumption observed during the late afternoon was associated with photochemical processes. The low rates of dark H2O2 consumption in incubation experiments are consistent with patterns observed in surface samples during the night when no rapid concentration decreases were observed (Fig. 2). The loss of hydrogen peroxide followed first order kinetics in both incubated storage experiments (Fig. 5) and the decay of hydrogen peroxide input from rain in August (Fig. 1). The rate constant obtained for the loss of the hydrogen peroxide signal in surface seawater from rain in Fig. 1 of 0.0085 h 1 was the same as that obtained from

0

40

80

120

160

0

4

3 2

25

1

Depth (m)

50

75

100

Fig. 6. Depth profiles for hydrogen peroxide concentrations in August 1999 (profiles 1 and 2) and March 2000 (profiles 3 and 4).

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same (b25 nM) for both seasons below approximately 50 m. The higher concentrations observed throughout the mixed layer in August reflect higher atmospheric inputs in August relative to March. Hydrogen peroxide profiles measured on four separate occasions before and after rain events during the August sampling period showed significant increases after rain events (Kieber et al., 2001). The input of rainfall hydrogen peroxide was observed throughout the 25-m mixed layer with surface concentrations twofold larger in the morning after a rain event. The integrated increase in hydrogen peroxide after the rain from 0 to 90 m was 1860 Amoles almost all of which could be accounted for by the peroxide added from rain (Kieber et al., 2001).

4. Summary 1. Patterns of variation in hydrogen peroxide concentrations in surface seawater at BATS were drastically different in August of 1999 compared with March of 2000. In August, hydrogen peroxide concentrations were primarily controlled by input from rain, whereas in March, which had very little rain, they were controlled by photochemical processes and showed diurnal variation. BATS receives approximately the same amount of rain per month throughout the year (Bermuda Weather Service data), which suggests that input of hydrogen peroxide via rain is usually the dominant source to surface seawater at BATS for most of the year. 2. During the March 2000 cruise, surface water concentrations displayed a distinct diurnal pattern with maximum concentrations occurring at midday. The peak concentrations are preceded by a rapid photochemically induced production of H2O2 followed by an equally rapid photochemically induced consumption of H2O2, probably a secondary photochemical process with some direct photochemical loss also possible. This was followed by a much slower decline at night which was most likely biologically driven. The combination of these photochemical production and consumption processes results in approximately the same maximum and minimum concentrations over a 24-h period.

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3. The photochemical production rate of hydrogen peroxide in surface seawater was approximately 3 nM h 1 over a 12-h day. The decomposition of hydrogen peroxide followed first order kinetics with a rate constant of 0.009 h 1 in surface water and slower decomposition in seawater from 200 m. 4. Filtered seawater had lower productions rates compared to unfiltered seawater from the same depth suggesting biological production may contribute to surface seawater hydrogen peroxide concentrations at BATS, but it is not the dominant source.

Acknowledgements We would like to thank Bethany Jacobs for the assistance during the August cruise. NSF Grant, ATM-9729425, supported this study and ship time was supported provided by NSF Grant OCE9811208, Oliver Zafiriou (PI). The captain and crew of the R/V Endeavor provided invaluable assistance during this study. References Collen, J., del Rio, M.J., Garcia-Reina, G., Pederson, M., 1995. Photosynthetic production of hydrogen peroxide by Ulva rigida C. Ag. (Chlorophyta). Planta 196, 225 – 230. Cooper, W.J., Zepp, R.G., 1990. Hydrogen peroxide decay in waters with suspended sediments: evidence for biologically mediated processes. Canadian Journal of Fisheries and Aquatic Sciences 47, 888 – 893. Cooper, W.J., Zika, R.G., 1983. Photochemical formation of H2O2 in surface and ground waters exposed to sunlight. Science 220, 711 – 712. Cooper, W.J., Zika, R.G., Saltzman, E.S., 1987. The contribution of rainwater to variability in surface ocean hydrogen peroxide. Journal of Geophysical Research 92, 2970 – 2980. Cooper, W.J., Zika, R.G., Petasne, R.G., Plane, J.M.C., 1988. Photochemical formation of H2O2 in natural waters exposed to sunlight. Environmental Science and Technology 22, 1156 – 1160. Cooper, W.J., Zika, R.G., Petasne, R.G., Fischer, A.M., 1989. Sunlight induced photochemistry of humic substances in natural waters: major reactive species. In: Maccarthy, P., Suffett, I.H. (Eds.), Influence of Aquatic Humic Substances on Fate and Treatment of Pollutants, American Chemical Society, Advances in Chemistry, vol. 219, pp. 333 – 362. Cooper, W.J., Moegling, J.K., Kieber, R.J., Kiddle, J.J., 2000. A chemiluminescence method for the analysis of H2O2 in natural waters. Marine Chemistry 70, 191 – 200.

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G.B. Avery Jr. et al. / Marine Chemistry 97 (2005) 236–244

Hanson, A.K., Tindale, N.W., Abdel-Moati, M.A.R., 2001. An equatorial Pacific rain event: influence of the distribution of iron and hydrogen peroxide in surface waters. Marine Chemistry 75, 69 – 88. Kieber, R.J., Helz, G.R., 1986. Two method verification of hydrogen peroxide determinations in natural waters. Analytical Chemistry 58, 2312 – 2315. Kieber, R.J., Helz, G.R., 1995. Temporal and seasonal variations of hydrogen peroxide levels in Estuarine waters. Estuarine, Coastal and Shelf Science 40, 495 – 503. Kieber, D.J., Yocis, B.H., Mopper, K., 1997. Free-floating drifter for photochemical studies in the water column. Limnology and Oceanography 42, 1829 – 1833. Kieber, R.J., Cooper, W.J., Willey, J.D., Avery Jr., G.B., 2001. Hydrogen peroxide at the Bermuda Atlantic Time Series Station: Part 1. Temporal variability of atmospheric hydrogen peroxide and its influence on seawater concentrations. Journal of Atmospheric Chemistry 39, 1 – 13. Micinski, E., Ball, L.A., Zafiriou, O.C., 1993. Photochemical oxygen activation: superoxide radical detection and production rates in the eastern Caribbean. Journal of Geophysical Research 98, 2299 – 2306. Miller, W.L., Kester, D.R., 1994. Peroxide variations in the Sargasso Sea. Marine Chemistry 48, 17 – 29. Moffett, J.W., Zafiriou, O.C., 1990. An investigation of hydrogen peroxide chemistry in a coastal marine environment us H2 18O and 18O2. Limnology and Oceanography 35, 1221 – 1229. Moffett, J.W., Zafiriou, O.C., 1993. The photochemical decomposition of hydrogen peroxide in surface waters of the eastern Caribbean and Orinoco River. Journal of Geophysical Research 98, 2307 – 2313. Obernosterer, I., Ruardij, P., Herndl, G.J., 2000. Spatial and diurnal dynamics of dissolved organic matter (DOM) fluorescence and H2O2 and the photochemical oxygen demand of surface water DOM across the subtropical Atlantic Ocean. Limnology and Oceanography 46, 632 – 643. Palenik, B., Morel, F.M.M., 1988. Dark production of hydrogen peroxide in the Sargasso Sea. Limnology and Oceanography 35, 1606 – 1611. Palenik, B., Morel, F.M.M., 1990a. Amino acid utilization by marine phytoplankton: a novel mechanism. Limnology and Oceanography 35, 260 – 269. Palenik, B., Morel, F.M.M., 1990b. Comparison of l-amino acid oxidases from several marine phytoplankton. Marine Ecology. Progress Series 59, 195 – 201. Palenik, B., Zafiriou, O.C., Morel, F.M.M., 1987. Hydrogen peroxide production by a marine phytoplankton. Limnology and Oceanography 32, 1365 – 1369.

Palenik, B., Kieber, D.J., Morel, F.M.M., 1989. Dissolved organic nitrogen use by phytoplankton: the role of cell-surface enzymes. Biological Oceanography 6, 347 – 354. Patterson, C.O., Myers, J., 1973. Photosynthetic production of hydrogen peroxide by Anacystis nidulans. Plant Physiology 51, 104 – 109. Petasne, R.G., Zika, R.G., 1987. Fate of superoxide in coastal seawater. Nature (London) 325, 516 – 518. Petasne, R.G., Zika, R.G., 1997. Hydrogen peroxide lifetimes in south Florida coastal and offshore water. Marine Chemistry 56, 215 – 225. Roncel, M., Navarro, J.A., Rosa, M.D.L., 1989. Coupling of solar energy to hydrogen peroxide production in the Cyanobacterium Anacystis nidulans. Applied and Environmental Microbiology 55, 483 – 487. Roulier, M.A., Palenik, B., Morel, F.M.M., 1990. A method for the measurement of choline and hydrogen peroxide in seawater. Marine Chemistry 30, 409 – 421. Stevens Jr., S.E., Patterson, C.O., Myers, J., 1973. The production of hydrogen peroxide by blue–green algae: a survey. Journal of Phycology 9, 427 – 430. Thompson, A.M., Zafiriou, O.C., 1983. Air–sea fluxes of transient atmospheric species. Journal of Geophysical Research 88, 6696 – 6708. Yocis, B.H., Kieber, D.J., Mopper, K., 2000. Photochemical production of hydrogen peroxide in Antarctic waters. Deep-Sea Research 1 (47), 1077 – 1099. Yuan, J., Shiller, A.M., 2000. The variations of hydrogen peroxide in rain water over the South and Central Atlantic Ocean. Atmospheric Environment 34, 3973 – 3980. Yuan, J., Shiller, A.M., 2001. The distribution of hydrogen peroxide in the Center Atlantic Ocean. Deep-Sea Research II 48, 2947 – 2970. Zafiriou, O.C., 1983. Natural water photochemistry. In: Riley, J.P., Chester, R. (Eds.), Chemical Oceanography, vol. 8. Academic Press, pp. 339 – 379. Zepp, R.G., Skurlatov, Y.I., Pierce, J.T., 1987. Algal-induced decay and formation of hydrogen peroxide in water: its possible role in oxidation of anilines by algae. In: Zika, R.G., Cooper, W.J. (Eds.), Photochemistry of Environmental Aquatic Systems, ACS Symposium Series, vol. 327. American Chemical Society, Washington, DC, pp. 215 – 224. Zika, R.G., 1981. Marine organic photochemistry. In: Duursma, E.K., Dawson, R. (Eds.), Marine Organic Chemistry. Elsevier Scientific Pub., Amsterdam, pp. 299 – 325.