- Email: [email protected]
Heavy metals in sediments of the inner shelf of the Beaufort Sea, northern arctic Alaska
Marine Pollution Bulletin
detection, these drawbacks were greatly eliminated by splitting the total fluorescence of the sample into distinct portions of its individual fluorescing constituents. In general, the HPLC procedure with fluorescence detection does not need a purification step, as, for example, GC analysis would need. It is quite a simple and rugged method, so it can be used on board a ship. Owing to the fact that, in many cases, the fluorescence spectrometer used for the classical UVF method to determine THC can be equipped with a flow-through cell, the upgrading with an HPLC is not very expensive. As has been demonstrated in this study, the method is sensitive enough to investigate samples even from open ocean areas with very low concentrations down to 0.1 ~tg 1-I THC. The combination of HPLC with fluorescence detection allows a much better characterization of water extracts and yields far more information about the composition than the spectroscopic analysis alone. By this technique, it could be demonstrated that a great part of the fluorescence measured by the UVF method originates from non-hydrocarbonic compounds. More detailed investigations about the nature of selected fluorescing compounds are currently in progress. The expert technical assistance of Mrs K. Jerzycki-Brandes is gratefully acknowledged.
Anon. (1982). Proceedings of a workshop on the analysis of hydrocarbons in seawater. March 23-April 3, 198I. Baltic Sea Environment Proceedings No. 6. Helsinki Commission. Barth, T. (1984). Weathering of crude oil in natural marine environments: The concentration of polar degradation products in water under oil as measured in several field studies. Chernosphere 13, 6 7 86. Berthou, F., Ducreux, J. & Bodennec, G. (1985). Analysis of watersoluble acidic compounds derived from spilled oil in a controlled marine enclosure. Intern. J. Environ. Anal. Chem. 2 I. 267-282. Ducreux, J., Berthou, F. & Bodennec, G. (1986). Etude du vieillissement d'un petrole brut repandu a la surface de Feau de mer dans des conditions naturelles, lntern. J. Environ. Anal. Chem. 24, 8 5 - l 11. International Oceanographic Commission. (1984). Manual for monitoring oil and dissolved/dispersed petroleum hydrocarbons in marine waters and on beaches, I O C / U N E P , Paris, Manuals and Guides No. 13. Knap, A. H., Burns, K. A., Dawson, R., Ehrhardt, M. & Palmork, K. H. (I986). Dissolved/dispersed hydrocarbons, tarballs and the surface microlayer: Experiences from an I O C / U N E P workshop in Bermuda, December, 1984. "~lar. Pollut. Bull. 17,313-319. Law, R. J., Marchand, M., Dahlmanm G. & Fileman, T. W. (1987). Results of two bilateral comparisons of the determination of hydrocarbon concentrations in coastal seawater by fluorescence spectroscopy. Mar. Pollut. Bull. 1 8 , 4 8 6 - 4 8 9 . Stadler, D. & Schomaker, K. (1977). Ein Glaskugelsch6pfer zur kontaminationsfreien Entnahme von Seewasser unter der Oberfi~iche fiir die Analyse von Kohlenwasserstoffen uml halogenierten Kohlenwasserstoffen. Dr. tfydrogr. Z. 30, 20-25. Theobald, N. (1988). Rapid preliminary separation of petroleum hydrocarbons by solid-phase extraction cartridges. Anal. ('him. Acta 204,135-144. Tjessem, K. & Palmork, K. H. (1984). An overview of auto/photooxidation of petroleum in the marine environment. ICES, Marine Chemistry Working Group, 1-25.
Edited by E. I. Hamilton Marine Po/httionBulletin. Volume20. No. 3. pp 140-143. 1989
Primed in Great Britain
The objective of BASELINE is to publish short communications for the concentration and distribution of elements and compounds in the marine environment. Only those papers which clearly identify the quality of the data will be considered for publication. Contributors to Baseline should refer to 'Baseline--A Record of Contamination Levels' (Mar. Pollut. Bull. 13,217-218).
Heavy Metals in Sediments of the Inner Shelf of the Beaufort Sea, Northern Arctic Alaska Since the discovery of a major oil field at Prudhoe Bay in 1968 there has been a dramatic surge in exploration and exploitation of petroleum along the northern arctic coast and nearshore of Alaska. The possible environmental contamination from this ongoing development was a significant impetus for determining the abundances of heavy metals in the sediments of the adjacent inner shelf of the Beaufort Sea. Comprehensive reviews of the nearshore environments and ecosystems of the 140
0025-326X/89 $3.00+000 © 1989 PergamonPre~spie
Beaufort Sea are found in Naidu & Mowatt (1975) and Barnes et aL (1984). This paper presents baseline data on sediment heavy metals available from four distinct geographic units along the inner shelf, namely Harrison Bay, Simpson Lagoon-Gwydyr Bay, Stefansson Sound-Prudhoe Bay, and Beaufort Lagoon (Fig. 1). The area encompassed extends about 430 km along the Beaufort Sea coast of Alaska. The remaining stations, located outside these four, relatively sheltered environments, were grouped separately under the title: Open Shelf. This group of stations extends seaward to the inner edge of the stamukhi zone (18-35 m depths), where grounded ice ridges protect the inner shelf from impingement by offshore pack ice (Barnes et al., 1984). The sediments are generally carbonate and organicpoor sandy muds or muddy sands in oxic conditions. The averages in the five environments range from 4 to 13% for carbonate (CO3=) and 0.6 to 1.1% by weight for organic carbon (Table 1). Surface sediments were collected from 1970 to 1980 by Ekman or Van Veen grabs (2 dm3). This data is the earliest and most comprehensive of its kind, and presumably of highest quality, for northern arctic
Volume 2 0 / N u m b e r 3/March 1989
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Alaska (Sweeney, 1984). We are confident our data represent the natural abundances, since large-scale and protracted disturbances by modem technologies in the remote Alaskan Arctic are very recent. This paper therefore provides baselines to monitor chemical contamination by the activities of the petroleum and related industries there. A forthcoming paper will discuss details of the partitioning patterns of the metals in the sediments. To minimize metal contamination, only the interior portion of each sample was removed from the grab into polyethylene bags or plastic boxes and stored frozen. Details of the laboratory analytical procedures are included in Naidu e t al. (1982) and Sweeney (1984). A brief summary of the procedures follows. In the laboratory, after thawing and mixing splits of sediments were taken for grain-size (50 gm) and heavy-metal (80 gin) analyses. Granulometric analysis and statistical grainsize parameters were obtained after Folk (1974). The 80 gm splits were dried at 60°C and about 30 gm from them were pulverized to a fine powder using an agate mortar and pestle. The remaining portions were lightly disaggregated to preserve the integrity of their natural granulometric compositions for the partial-extraction study. Both powders and disaggregates were stored in acid-rinsed glass vials. All labware was acid rinsed and reagent blanks were analysed each time to correct for any minor contamination. The powders were digested with HF-HNO3 (HFNA) to determine total metal abundances (Rader & Grimaldi, 1961). Partial extractions with 1-M hydroxylamine hydrochloride in 25% acetic acid (HHAA) were performed on portions of selected disaggregate splits. This treatment is used to release portions of the heavy metals which are not bound with crystal lattices, e.g., the exchangeable, carbonate, and manganese and (some) iron-oxide fractions. Presumably, these operationally-
defined metal phases can be readily mobilized into solution under reduced Eh and pH environmental conditions (Chester & Hughes, 1967). Analyses on digests and extracts were accomplished by atomic absorption spectrophotometry (AAS) with Dz-Arc background correction, using a Perkin-Elmer Model 603 (flame) and Model 360 with HGAo2100 graphite furnace. Calibration was performed by the method of standard additions using AAS standards. Based on detailed studies of replicate station grabs from Simpson Lagoon (Sweeney, 1984), our sediment samples represent their corresponding stations with a precision (%cv) of 10-20%; for HFNA-Ni, Fe, V, Zn, Cr it is 7-9%. Precision of analysis is generally within 5%, except that for HHAA-V, Cr, Co it is about 10% (Sweeney, 1984). USGS AGV-1 and BCR-1 Standard Rock powders underwent total analyses to check the analytical accuracy of our HFNA procedure. We obtained results generally within 5% of the averages reported by Flanagan (1969, 1973), based on multilaboratory contributions for each metal analysed except nickel, for which our estimates were low in comparison by at least 30% (Sweeney, 1984). This paper presents the mean, range, number of samples (n), standard deviation (S), and percent coefficient of variation (%cv) for each sediment variable in each of the five geographic units. Table 1 lists the depths, granulometric compositions, and organic carbon and carbonate abundances. Table.<; 2 and 3 list the total and extractable metal concentrations, respectively. Individual station data are available upon request from the authors. No reflection of the distinct weathering and depositional regimes in the Alaskan Arctic (Naidu & Mowatt, 1975) was identified in the heavymetal abundances in the sediments, i.e., the abundances are not dissimilar to natural levels in corresponding carbonate and organic-poor sandy mud or muddy sand 141
Marine Pollution Bulletin
TABLE 1 Means and ranges, along with relevant statistics, of depth, grain-size parameters, organic carbon, and carbonate (C03") for sediments from the five geographic units* of this study.
TABLE 2 Means and ranges, along with relevant statistics, of total concentrations (gg g-~, except 104 lag g-~ for Fe) of heavy metals in sediments from the five geographic units* of this study.
Unit*
n
Range
Mean
S
% cv
Unit*
Depth (m) HB SL-GB SS-PB BL OS
21 53 27 17 19
1.5-10 0.3-3.5 0.6-8.8 0.2-3.2 7•6-17
4.7 2.0 4.3 2.1 14
3.1 0.7 2.4 1.1 2.6
66 35 55 52 19
%Gravel HB SL-GB SS-PB BL OS
20 53 27 17 17
-0 0-17 0.0-3.1 0.0-0.5 0-25
0 1.5 0.2 0.05 1.5
3.4 0.8 0.15 6.1
230 355 300 395
%Sand HB SL-GB SS-PB BL OS
20 53 27 17 17
3.4-96 7.7-98 7.1-98 1.4-98 7.4-98
41 43 55 41 48
32 23 31 37 31
77 53 55 90 66
%Silt HB SL-GB SS-PB BL OS
20 53 27 17 17
1.6-80 0.7-80 1.0-74 0.6-68 1.5-65
41 41 30 40 30
26 20 22 25 21
% Clay HB SL-GB SS-PB BL OS
20 53 27 17 17
1.3-82 1.0-40 0.4-47 0.6-52 0.0-55
18 14 14 19 20
19 7.2 13 14 17
%Mud HB SL-GB SS-PB BL OS
20 53 27 17 17
3.8-97 1.7-92 2.2-93 1.6-99 1.5-93
59 55 44 59 50
Mean size (O) HB SL-GB SS-PB BL OS
13 51 27 17 15
2.8-7.3 1.2-6.6 1.1-8.1 1.9-8.1 1.2-8.3
%CO 3" HB SL-GB SS-PB BL OS
9 51 22 17 14
%Organic carbon HB SL-GB SS-PB BL OS
9 51 22 17 14
n
Range
Mean
S
% cv
21 53 27 17 19
1.0-3.7 0.8-4.8 0.8-2.9 1.6-3.5 1.(I-3.3
2.5 2.0 1.8 2.6 2.0
0.7 0.7 0.5 0.6 0.7
27 34 27 21 37
21 53 27 17 19
150-650 115-555 205-420 200-465 105-425
380 265 280 345 275
134 99 54 77 97
35 37 19 22 35
HB SL-GB SS-PB BL OS
21 53 27 17 19
41-170 28-160 40-105 32-100 35-130
89 78 71 69 75
32 26 18 20 31
36 33 25 29 41
62 49 72 62 71
Vanadium HB SL-GB SS-PB BL OS
20 53 25 17 18
48-145 29-240 59-135 50-145 31-165
92 78 83 100 95
32 30 20 23 41
35 38 24 23 43
105 52 92 74 84
Chromium HB SL-GB SS-PB BL OS
21 53 27 17 18
35-100 16-125 15- 87 25- 94 23-110
61 49 48 58 54
17 17 15 17 26
28 35 31 29 48
32 24 31 37 32
54 44 69 63 64
Nickel HB SL-GB SS-PB BL OS
21 53 27 17 19
15-49 8.4-59 15-43 11-35 7.0-49
31 25 29 25 25
9 8 7.0 6.8 11
29 32 25 27 43
5.3 4.5 4.5 5.2 4.8
1.5 1.3 1.8 2.0 2.2
28 28 41 38 46
Copper HB SL-GB SS-PB BL OS
21 53 27 17 19
7 -35 6.3-83 9 -29 8 -28 7.0-40
22 19 16 20 19
8.4 11 5.2 5.9 11
38 57 32 29 56
0.9-9.6 1.4-19 3.0-18 2.7-9.6 2.3-14
4.1 8.6 13 6.9 8.2
3.0 3.9 3.8 2.2 3.9
73 45 28 32 47
Cobalt HB SL-GB SS-PB BL OS
21 53 27 17 18
5.4-16 3.3-18 4 -11 5 -18 4.0-16
10 7.7 7.2 12 8.2
3.5 2.3 1.9 3.5 3.6
35 29 27 28 44
0.1-1.4 0.1-4.4 0.0-2.2 0.0-4.3 0.0-2.2
0.8 1.1 0.6 0.8 0.6
0.5 0.8 0.5 1.1 0.7
65 71 77 140 105
Iron
Manganese HB SL-GB SS-PB BL OS Zinc
*HB: Harrison Bay; SL-GB: Simpson Lagoon-Gwydyr Bay; SS-PB: Stefansson Sound-Prudhoe Bay; BL: Beaufort Lagoon; OS: Open Shelf.
142
HB SL-GB SS-PB BL OS
*HB: Harrison Bay; SL-GB: Simpson Lagoon-Gwydyr Bay; SS-PB: Stefansson Sound-Prudhoe Bay; BL: Beaufort Lagoon; OS: Open Shelf•
Volume 20/Number 3/March 1989 TABLE 3
nearshore
Means and ranges, along with relevant statistics, of concentrations (gg g-~, except 104 gg g-i for Fe) of heavy metals in hydroxylamine hydrochloride-acetic acid extracts (Chester & Hughes, 1967) of sediments from the five geographic units* of this study. Unit*
n
Range
Mean
S
% cv
4 40 10 16 6
0.27-0.58 0.03-0.46 0.05-1.1 0.0 -0.5 0.2 -1.4
0.42 0.22 0.31 0.30 0.54
0.15 0.10 0.29 0.17 0.45
36 46 94 57 84
4 40 10 16 6
105-210 45-365 90-250 65-265 55-350
145 140 150 200 170
52 78 45 49 103
35 56 30 24 60
4 40 11 17 6
13 -30 2.5-23 9 -43 3 -31 15 -30
20 13 22 15 22
8 5.7 9.4 8 6.2
39 43 43 53 28
Iron
HB SL-GB SS-PB BL OS Manganese
HB SL-GB SS-PB BL OS Zinc
HB SL-GB SS-PB BL OS Vanadium HB
4
SL-GB SS-PB BL OS
40 ll 17 6
6 -18 1.1- 7.3 2.2-14 1 -16 3.0-23
12 4.1 5.5 9 12
6.4 1.5 3.6 5.4 7.7
53 38 66 60 64
4 40 9 17 5
1.5-2.7 0.0-2.1 0.7-2.5 0.3-3.0 1.0-5.0
2.2 1.1 1.6 1.6 3.0
0.5 0.6 0.5 0.7 1.8
25 52 31 44 60
4 40 lI 17 6
2.0- 5.0 0.2- 6.1 0.0- 4.0 0.8- 6.7 0.0-12
3.2 3.5 2.2 3.2 3.8
1.5 1.6 1.3 1.4 4.2
46 45 58 44 110
4 40 11 !7 6
3.5- 6.5 0.4- 4.8 1.0- 7.0 0.6- 7.2 1.0-17
4.9 2.6 2.2 4.1 6.9
1.4 0.8 1.9 2.1 5.6
28 31 84 51 81
4 39 0 17 3
1.0-2.5 0.2-3.5
1.8 2.0
0.9 0.8
49 42
1.3-5.0 1.0-5.5
3.5 3.3
1.2 2.3
34 68
deposits from many tropical and temperate
regions of the world (Sweeney, 1984). Analysis of the data from western Simpson Lagoon ( N a i d u et al., 1 9 8 2 ; S w e e n e y , 1 9 8 4 ) r e v e a l e d t h a t t h e p r o p o r t i o n o f silt a n d c l a y is t h e m o s t i m p o r t a n t f a c t o r i n t h e d i s t r i b u t i o n o f h e a v y - m e t a l a b u n d a n c e s . T h i s is consistent with many studies of nearshore sediments throughout the world. Nickel was found to be the best discriminator b e t w e e n d i f f e r e n t t e x t u r a l c l a s s e s in S i m p s o n L a g o o n ( S w e e n e y , 1 9 8 4 ) . It is e x p e c t e d t h a t f u r t h e r a n a l y s i s o f o u r d a t a will i d e n t i f y a d d i t i o n a l factors for the abundances of heavy metals in the sediments of the inner shelf of the Beaufort Sea, Alaska. This research was supported by the US Bureau of Land Management through interagency agreement with NOAA, under which a multi-year programme responding to the needs of the petroleum development of the Alaskan continental shelf is managed by the OCSEAP office. We are also indebted to the officers and crew of the USCG Glacierand Drs. R W. Barnes and E. Reimnitz for their help in the sample collection. This is Contribution No. 709 of the Institute of Marine Science, University of Alaska Fairbanks.
M I C H A E L D. S W E E N E Y * A. S A T H Y NAIDU* *335 London Place, Anaheim, CA 92806," tlnstitute of Marine Science, University of Alaska Fairbanks, Fairbanks, A K 99775-1080, USA
Chromium
HB SL-GB SS-PB BL OS Nickel
HB SL-GB SS-PB BL OS Copper
HB SL-GB SS-PB BL OS Cobalt
HB SL-GB SS-PB BL OS
*HB: Harrison Bay; SL-GB: Simpson Lagoon-Gwydyr Bay. SS-PB: Stefansson Sound-Prndhoe Bay; BL: Beaufort Lagoon; OS: Open Shelf.
Barnes, P. W., Reimnitz, E. & Schell, D. M., eds. (1984). The Alaskan Beaufort Sea: Ecosystems and Environments. Academic Press, Orlando, FL. Chester, R. & Hughes, M. J. (1967). A chemical technique for the separation of ferromanganese minerals, carbonate minerals and adsorbed trace elements from pelagic sediments. Chem. GeoL 2, 249-262. Flanagan, F. J. (1969). US Geological Survey Standards--H. First compilation of data for the new USGS Rocks. Geochim. Cosmochim. Acta 33, 81-120. Flanagan, F. J. (1973). 1972 values for International Reference sampies. Geochirn. Comochim. Acta 37, 1189-1200. Folk, R. L. (1974). Petrology of Sedimentary Rocks. Hemphill, Austin, Texas. Naidu, A. S. & Mowatt, T. C. (1975). Depositional environments and sediment characteristics of the Colville and adjacent deltas, northern arctic Alaska. In: Deltas:Modelsfor Subsurface Exploration (M. L. S. Broussard, ed.), pp. 283-309. Houston Geol. Soc., Houston, Texas. Naidu, A. S., Larsen, L. H, Mowatt, T. C., Sweeney, M. D. & Weiss, H. V. (1982). Aspects of size distributions, clay mineralogy, :rod geochemistry of sediments of the Beaufort Sea and adjacent deltas, north arctic Alaska. US Dept. Commerce, NOAA, OCSEAP Final Rept., 33 (1985): 315-429, Anchorage, Alaska. Rader, L. F. & Grimaldi, F. S. (1961). Chemical analyses for selected minor elements in Pierre Shale. USGS Prof. Pap. 391-A, pp. A I A45. Sweeney, M. D. (1984). Heavy metals in the sediments of an arctic lagoon, northern Alaska. MS Thesis, Institute of Marine Science, University of Alaska Fairbanks, Alaska.
143
detection, these drawbacks were greatly eliminated by splitting the total fluorescence of the sample into distinct portions of its individual fluorescing constituents. In general, the HPLC procedure with fluorescence detection does not need a purification step, as, for example, GC analysis would need. It is quite a simple and rugged method, so it can be used on board a ship. Owing to the fact that, in many cases, the fluorescence spectrometer used for the classical UVF method to determine THC can be equipped with a flow-through cell, the upgrading with an HPLC is not very expensive. As has been demonstrated in this study, the method is sensitive enough to investigate samples even from open ocean areas with very low concentrations down to 0.1 ~tg 1-I THC. The combination of HPLC with fluorescence detection allows a much better characterization of water extracts and yields far more information about the composition than the spectroscopic analysis alone. By this technique, it could be demonstrated that a great part of the fluorescence measured by the UVF method originates from non-hydrocarbonic compounds. More detailed investigations about the nature of selected fluorescing compounds are currently in progress. The expert technical assistance of Mrs K. Jerzycki-Brandes is gratefully acknowledged.
Anon. (1982). Proceedings of a workshop on the analysis of hydrocarbons in seawater. March 23-April 3, 198I. Baltic Sea Environment Proceedings No. 6. Helsinki Commission. Barth, T. (1984). Weathering of crude oil in natural marine environments: The concentration of polar degradation products in water under oil as measured in several field studies. Chernosphere 13, 6 7 86. Berthou, F., Ducreux, J. & Bodennec, G. (1985). Analysis of watersoluble acidic compounds derived from spilled oil in a controlled marine enclosure. Intern. J. Environ. Anal. Chem. 2 I. 267-282. Ducreux, J., Berthou, F. & Bodennec, G. (1986). Etude du vieillissement d'un petrole brut repandu a la surface de Feau de mer dans des conditions naturelles, lntern. J. Environ. Anal. Chem. 24, 8 5 - l 11. International Oceanographic Commission. (1984). Manual for monitoring oil and dissolved/dispersed petroleum hydrocarbons in marine waters and on beaches, I O C / U N E P , Paris, Manuals and Guides No. 13. Knap, A. H., Burns, K. A., Dawson, R., Ehrhardt, M. & Palmork, K. H. (I986). Dissolved/dispersed hydrocarbons, tarballs and the surface microlayer: Experiences from an I O C / U N E P workshop in Bermuda, December, 1984. "~lar. Pollut. Bull. 17,313-319. Law, R. J., Marchand, M., Dahlmanm G. & Fileman, T. W. (1987). Results of two bilateral comparisons of the determination of hydrocarbon concentrations in coastal seawater by fluorescence spectroscopy. Mar. Pollut. Bull. 1 8 , 4 8 6 - 4 8 9 . Stadler, D. & Schomaker, K. (1977). Ein Glaskugelsch6pfer zur kontaminationsfreien Entnahme von Seewasser unter der Oberfi~iche fiir die Analyse von Kohlenwasserstoffen uml halogenierten Kohlenwasserstoffen. Dr. tfydrogr. Z. 30, 20-25. Theobald, N. (1988). Rapid preliminary separation of petroleum hydrocarbons by solid-phase extraction cartridges. Anal. ('him. Acta 204,135-144. Tjessem, K. & Palmork, K. H. (1984). An overview of auto/photooxidation of petroleum in the marine environment. ICES, Marine Chemistry Working Group, 1-25.
Edited by E. I. Hamilton Marine Po/httionBulletin. Volume20. No. 3. pp 140-143. 1989
Primed in Great Britain
The objective of BASELINE is to publish short communications for the concentration and distribution of elements and compounds in the marine environment. Only those papers which clearly identify the quality of the data will be considered for publication. Contributors to Baseline should refer to 'Baseline--A Record of Contamination Levels' (Mar. Pollut. Bull. 13,217-218).
Heavy Metals in Sediments of the Inner Shelf of the Beaufort Sea, Northern Arctic Alaska Since the discovery of a major oil field at Prudhoe Bay in 1968 there has been a dramatic surge in exploration and exploitation of petroleum along the northern arctic coast and nearshore of Alaska. The possible environmental contamination from this ongoing development was a significant impetus for determining the abundances of heavy metals in the sediments of the adjacent inner shelf of the Beaufort Sea. Comprehensive reviews of the nearshore environments and ecosystems of the 140
0025-326X/89 $3.00+000 © 1989 PergamonPre~spie
Beaufort Sea are found in Naidu & Mowatt (1975) and Barnes et aL (1984). This paper presents baseline data on sediment heavy metals available from four distinct geographic units along the inner shelf, namely Harrison Bay, Simpson Lagoon-Gwydyr Bay, Stefansson Sound-Prudhoe Bay, and Beaufort Lagoon (Fig. 1). The area encompassed extends about 430 km along the Beaufort Sea coast of Alaska. The remaining stations, located outside these four, relatively sheltered environments, were grouped separately under the title: Open Shelf. This group of stations extends seaward to the inner edge of the stamukhi zone (18-35 m depths), where grounded ice ridges protect the inner shelf from impingement by offshore pack ice (Barnes et al., 1984). The sediments are generally carbonate and organicpoor sandy muds or muddy sands in oxic conditions. The averages in the five environments range from 4 to 13% for carbonate (CO3=) and 0.6 to 1.1% by weight for organic carbon (Table 1). Surface sediments were collected from 1970 to 1980 by Ekman or Van Veen grabs (2 dm3). This data is the earliest and most comprehensive of its kind, and presumably of highest quality, for northern arctic
Volume 2 0 / N u m b e r 3/March 1989
72°I
_ -
72
SEA
BEAUFORT
PO,-T BARROW EcSO~ ~PL.O~VER LAGOON
PRUOHOE BAY LAGOON
_.p,= ~PINGOK
•
=.
•
1
..
. "g. • "'** °.° e.~-,.j~l . .~. % "* V-48 i ° °
•
70"~0' 149 HCL~PET T
•
.
•
B
5o
GWYDYR BZIY
,,,,,°=lT
--~#
"~'.
°
•
,~
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~'~
BEAUFORT
MIDWAY IS
\ ='1~"i~el~ • •1
/,
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IS
,'-,, , 2,'/'~.---~,CROSS L~I CROSS
70 •
•
... •
. ~.
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r
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~-~=,~
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MAGUIRFELAxMAN
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,E
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"-"
,/~
\
it'>'/7"//{(
',°'C ~ I / < '
I/
]
/
i
~
II .
.... oDD.. DEMARCATION
~#LC.I~IETER$
.-...A......-~ ~ I56 •
154 °
1~2"
I~0"
148"
I46"
144"
142"
Fig. 1 Study area, Beaufort Sea nearshore, north arctic Alaska.
Alaska (Sweeney, 1984). We are confident our data represent the natural abundances, since large-scale and protracted disturbances by modem technologies in the remote Alaskan Arctic are very recent. This paper therefore provides baselines to monitor chemical contamination by the activities of the petroleum and related industries there. A forthcoming paper will discuss details of the partitioning patterns of the metals in the sediments. To minimize metal contamination, only the interior portion of each sample was removed from the grab into polyethylene bags or plastic boxes and stored frozen. Details of the laboratory analytical procedures are included in Naidu e t al. (1982) and Sweeney (1984). A brief summary of the procedures follows. In the laboratory, after thawing and mixing splits of sediments were taken for grain-size (50 gm) and heavy-metal (80 gin) analyses. Granulometric analysis and statistical grainsize parameters were obtained after Folk (1974). The 80 gm splits were dried at 60°C and about 30 gm from them were pulverized to a fine powder using an agate mortar and pestle. The remaining portions were lightly disaggregated to preserve the integrity of their natural granulometric compositions for the partial-extraction study. Both powders and disaggregates were stored in acid-rinsed glass vials. All labware was acid rinsed and reagent blanks were analysed each time to correct for any minor contamination. The powders were digested with HF-HNO3 (HFNA) to determine total metal abundances (Rader & Grimaldi, 1961). Partial extractions with 1-M hydroxylamine hydrochloride in 25% acetic acid (HHAA) were performed on portions of selected disaggregate splits. This treatment is used to release portions of the heavy metals which are not bound with crystal lattices, e.g., the exchangeable, carbonate, and manganese and (some) iron-oxide fractions. Presumably, these operationally-
defined metal phases can be readily mobilized into solution under reduced Eh and pH environmental conditions (Chester & Hughes, 1967). Analyses on digests and extracts were accomplished by atomic absorption spectrophotometry (AAS) with Dz-Arc background correction, using a Perkin-Elmer Model 603 (flame) and Model 360 with HGAo2100 graphite furnace. Calibration was performed by the method of standard additions using AAS standards. Based on detailed studies of replicate station grabs from Simpson Lagoon (Sweeney, 1984), our sediment samples represent their corresponding stations with a precision (%cv) of 10-20%; for HFNA-Ni, Fe, V, Zn, Cr it is 7-9%. Precision of analysis is generally within 5%, except that for HHAA-V, Cr, Co it is about 10% (Sweeney, 1984). USGS AGV-1 and BCR-1 Standard Rock powders underwent total analyses to check the analytical accuracy of our HFNA procedure. We obtained results generally within 5% of the averages reported by Flanagan (1969, 1973), based on multilaboratory contributions for each metal analysed except nickel, for which our estimates were low in comparison by at least 30% (Sweeney, 1984). This paper presents the mean, range, number of samples (n), standard deviation (S), and percent coefficient of variation (%cv) for each sediment variable in each of the five geographic units. Table 1 lists the depths, granulometric compositions, and organic carbon and carbonate abundances. Table.<; 2 and 3 list the total and extractable metal concentrations, respectively. Individual station data are available upon request from the authors. No reflection of the distinct weathering and depositional regimes in the Alaskan Arctic (Naidu & Mowatt, 1975) was identified in the heavymetal abundances in the sediments, i.e., the abundances are not dissimilar to natural levels in corresponding carbonate and organic-poor sandy mud or muddy sand 141
Marine Pollution Bulletin
TABLE 1 Means and ranges, along with relevant statistics, of depth, grain-size parameters, organic carbon, and carbonate (C03") for sediments from the five geographic units* of this study.
TABLE 2 Means and ranges, along with relevant statistics, of total concentrations (gg g-~, except 104 lag g-~ for Fe) of heavy metals in sediments from the five geographic units* of this study.
Unit*
n
Range
Mean
S
% cv
Unit*
Depth (m) HB SL-GB SS-PB BL OS
21 53 27 17 19
1.5-10 0.3-3.5 0.6-8.8 0.2-3.2 7•6-17
4.7 2.0 4.3 2.1 14
3.1 0.7 2.4 1.1 2.6
66 35 55 52 19
%Gravel HB SL-GB SS-PB BL OS
20 53 27 17 17
-0 0-17 0.0-3.1 0.0-0.5 0-25
0 1.5 0.2 0.05 1.5
3.4 0.8 0.15 6.1
230 355 300 395
%Sand HB SL-GB SS-PB BL OS
20 53 27 17 17
3.4-96 7.7-98 7.1-98 1.4-98 7.4-98
41 43 55 41 48
32 23 31 37 31
77 53 55 90 66
%Silt HB SL-GB SS-PB BL OS
20 53 27 17 17
1.6-80 0.7-80 1.0-74 0.6-68 1.5-65
41 41 30 40 30
26 20 22 25 21
% Clay HB SL-GB SS-PB BL OS
20 53 27 17 17
1.3-82 1.0-40 0.4-47 0.6-52 0.0-55
18 14 14 19 20
19 7.2 13 14 17
%Mud HB SL-GB SS-PB BL OS
20 53 27 17 17
3.8-97 1.7-92 2.2-93 1.6-99 1.5-93
59 55 44 59 50
Mean size (O) HB SL-GB SS-PB BL OS
13 51 27 17 15
2.8-7.3 1.2-6.6 1.1-8.1 1.9-8.1 1.2-8.3
%CO 3" HB SL-GB SS-PB BL OS
9 51 22 17 14
%Organic carbon HB SL-GB SS-PB BL OS
9 51 22 17 14
n
Range
Mean
S
% cv
21 53 27 17 19
1.0-3.7 0.8-4.8 0.8-2.9 1.6-3.5 1.(I-3.3
2.5 2.0 1.8 2.6 2.0
0.7 0.7 0.5 0.6 0.7
27 34 27 21 37
21 53 27 17 19
150-650 115-555 205-420 200-465 105-425
380 265 280 345 275
134 99 54 77 97
35 37 19 22 35
HB SL-GB SS-PB BL OS
21 53 27 17 19
41-170 28-160 40-105 32-100 35-130
89 78 71 69 75
32 26 18 20 31
36 33 25 29 41
62 49 72 62 71
Vanadium HB SL-GB SS-PB BL OS
20 53 25 17 18
48-145 29-240 59-135 50-145 31-165
92 78 83 100 95
32 30 20 23 41
35 38 24 23 43
105 52 92 74 84
Chromium HB SL-GB SS-PB BL OS
21 53 27 17 18
35-100 16-125 15- 87 25- 94 23-110
61 49 48 58 54
17 17 15 17 26
28 35 31 29 48
32 24 31 37 32
54 44 69 63 64
Nickel HB SL-GB SS-PB BL OS
21 53 27 17 19
15-49 8.4-59 15-43 11-35 7.0-49
31 25 29 25 25
9 8 7.0 6.8 11
29 32 25 27 43
5.3 4.5 4.5 5.2 4.8
1.5 1.3 1.8 2.0 2.2
28 28 41 38 46
Copper HB SL-GB SS-PB BL OS
21 53 27 17 19
7 -35 6.3-83 9 -29 8 -28 7.0-40
22 19 16 20 19
8.4 11 5.2 5.9 11
38 57 32 29 56
0.9-9.6 1.4-19 3.0-18 2.7-9.6 2.3-14
4.1 8.6 13 6.9 8.2
3.0 3.9 3.8 2.2 3.9
73 45 28 32 47
Cobalt HB SL-GB SS-PB BL OS
21 53 27 17 18
5.4-16 3.3-18 4 -11 5 -18 4.0-16
10 7.7 7.2 12 8.2
3.5 2.3 1.9 3.5 3.6
35 29 27 28 44
0.1-1.4 0.1-4.4 0.0-2.2 0.0-4.3 0.0-2.2
0.8 1.1 0.6 0.8 0.6
0.5 0.8 0.5 1.1 0.7
65 71 77 140 105
Iron
Manganese HB SL-GB SS-PB BL OS Zinc
*HB: Harrison Bay; SL-GB: Simpson Lagoon-Gwydyr Bay; SS-PB: Stefansson Sound-Prudhoe Bay; BL: Beaufort Lagoon; OS: Open Shelf.
142
HB SL-GB SS-PB BL OS
*HB: Harrison Bay; SL-GB: Simpson Lagoon-Gwydyr Bay; SS-PB: Stefansson Sound-Prudhoe Bay; BL: Beaufort Lagoon; OS: Open Shelf•
Volume 20/Number 3/March 1989 TABLE 3
nearshore
Means and ranges, along with relevant statistics, of concentrations (gg g-~, except 104 gg g-i for Fe) of heavy metals in hydroxylamine hydrochloride-acetic acid extracts (Chester & Hughes, 1967) of sediments from the five geographic units* of this study. Unit*
n
Range
Mean
S
% cv
4 40 10 16 6
0.27-0.58 0.03-0.46 0.05-1.1 0.0 -0.5 0.2 -1.4
0.42 0.22 0.31 0.30 0.54
0.15 0.10 0.29 0.17 0.45
36 46 94 57 84
4 40 10 16 6
105-210 45-365 90-250 65-265 55-350
145 140 150 200 170
52 78 45 49 103
35 56 30 24 60
4 40 11 17 6
13 -30 2.5-23 9 -43 3 -31 15 -30
20 13 22 15 22
8 5.7 9.4 8 6.2
39 43 43 53 28
Iron
HB SL-GB SS-PB BL OS Manganese
HB SL-GB SS-PB BL OS Zinc
HB SL-GB SS-PB BL OS Vanadium HB
4
SL-GB SS-PB BL OS
40 ll 17 6
6 -18 1.1- 7.3 2.2-14 1 -16 3.0-23
12 4.1 5.5 9 12
6.4 1.5 3.6 5.4 7.7
53 38 66 60 64
4 40 9 17 5
1.5-2.7 0.0-2.1 0.7-2.5 0.3-3.0 1.0-5.0
2.2 1.1 1.6 1.6 3.0
0.5 0.6 0.5 0.7 1.8
25 52 31 44 60
4 40 lI 17 6
2.0- 5.0 0.2- 6.1 0.0- 4.0 0.8- 6.7 0.0-12
3.2 3.5 2.2 3.2 3.8
1.5 1.6 1.3 1.4 4.2
46 45 58 44 110
4 40 11 !7 6
3.5- 6.5 0.4- 4.8 1.0- 7.0 0.6- 7.2 1.0-17
4.9 2.6 2.2 4.1 6.9
1.4 0.8 1.9 2.1 5.6
28 31 84 51 81
4 39 0 17 3
1.0-2.5 0.2-3.5
1.8 2.0
0.9 0.8
49 42
1.3-5.0 1.0-5.5
3.5 3.3
1.2 2.3
34 68
deposits from many tropical and temperate
regions of the world (Sweeney, 1984). Analysis of the data from western Simpson Lagoon ( N a i d u et al., 1 9 8 2 ; S w e e n e y , 1 9 8 4 ) r e v e a l e d t h a t t h e p r o p o r t i o n o f silt a n d c l a y is t h e m o s t i m p o r t a n t f a c t o r i n t h e d i s t r i b u t i o n o f h e a v y - m e t a l a b u n d a n c e s . T h i s is consistent with many studies of nearshore sediments throughout the world. Nickel was found to be the best discriminator b e t w e e n d i f f e r e n t t e x t u r a l c l a s s e s in S i m p s o n L a g o o n ( S w e e n e y , 1 9 8 4 ) . It is e x p e c t e d t h a t f u r t h e r a n a l y s i s o f o u r d a t a will i d e n t i f y a d d i t i o n a l factors for the abundances of heavy metals in the sediments of the inner shelf of the Beaufort Sea, Alaska. This research was supported by the US Bureau of Land Management through interagency agreement with NOAA, under which a multi-year programme responding to the needs of the petroleum development of the Alaskan continental shelf is managed by the OCSEAP office. We are also indebted to the officers and crew of the USCG Glacierand Drs. R W. Barnes and E. Reimnitz for their help in the sample collection. This is Contribution No. 709 of the Institute of Marine Science, University of Alaska Fairbanks.
M I C H A E L D. S W E E N E Y * A. S A T H Y NAIDU* *335 London Place, Anaheim, CA 92806," tlnstitute of Marine Science, University of Alaska Fairbanks, Fairbanks, A K 99775-1080, USA
Chromium
HB SL-GB SS-PB BL OS Nickel
HB SL-GB SS-PB BL OS Copper
HB SL-GB SS-PB BL OS Cobalt
HB SL-GB SS-PB BL OS
*HB: Harrison Bay; SL-GB: Simpson Lagoon-Gwydyr Bay. SS-PB: Stefansson Sound-Prndhoe Bay; BL: Beaufort Lagoon; OS: Open Shelf.
Barnes, P. W., Reimnitz, E. & Schell, D. M., eds. (1984). The Alaskan Beaufort Sea: Ecosystems and Environments. Academic Press, Orlando, FL. Chester, R. & Hughes, M. J. (1967). A chemical technique for the separation of ferromanganese minerals, carbonate minerals and adsorbed trace elements from pelagic sediments. Chem. GeoL 2, 249-262. Flanagan, F. J. (1969). US Geological Survey Standards--H. First compilation of data for the new USGS Rocks. Geochim. Cosmochim. Acta 33, 81-120. Flanagan, F. J. (1973). 1972 values for International Reference sampies. Geochirn. Comochim. Acta 37, 1189-1200. Folk, R. L. (1974). Petrology of Sedimentary Rocks. Hemphill, Austin, Texas. Naidu, A. S. & Mowatt, T. C. (1975). Depositional environments and sediment characteristics of the Colville and adjacent deltas, northern arctic Alaska. In: Deltas:Modelsfor Subsurface Exploration (M. L. S. Broussard, ed.), pp. 283-309. Houston Geol. Soc., Houston, Texas. Naidu, A. S., Larsen, L. H, Mowatt, T. C., Sweeney, M. D. & Weiss, H. V. (1982). Aspects of size distributions, clay mineralogy, :rod geochemistry of sediments of the Beaufort Sea and adjacent deltas, north arctic Alaska. US Dept. Commerce, NOAA, OCSEAP Final Rept., 33 (1985): 315-429, Anchorage, Alaska. Rader, L. F. & Grimaldi, F. S. (1961). Chemical analyses for selected minor elements in Pierre Shale. USGS Prof. Pap. 391-A, pp. A I A45. Sweeney, M. D. (1984). Heavy metals in the sediments of an arctic lagoon, northern Alaska. MS Thesis, Institute of Marine Science, University of Alaska Fairbanks, Alaska.
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