8.3.2 Baseline Levels of Certain Trace Metals in 

 Sediment and Biota 



ALEXANDER J. KRYNITSKY* , CLIFFORD P. RICE* . and PASQUALE F. ROSCIGNO* 



'US Emironmental Protection Agency. Beltsville, Maiyland. USA 



' US Fish and Wildlife Service. Patuxent Wildlife Research Center, Laurel. Maryland. USA 



*US Fish and Wildlife Sen'ice. National Wetlands Research Center, Slidell. Louisiana, USA 



Introduction 



The Bering and Chukchi Seas are believed to be relatively 

 free from pollutants due to sparse human coastal populations 

 and limited industrial development. Increased industrial activity, 

 especially in petroleum exploration and production, is proposed 

 for the future and thus preliminary studies in determining 

 baseline concentrations of environmental contaminants are 

 necessary. Up to now, there have been no comprehensive 

 studies in determining baseline concentrations of trace metals 

 in sediment and biota in the Bering and Chukchi Seas by the US 

 or USSR. 



The US Fish and Wildlife Service was concerned that 

 tissues collected from Pacific walruses (Odohenus rosmarus 

 divergens) in the Bering Sea were high in cadmium (Taylor 

 et al., 1989). For example, the maximum concentrations of 

 cadmium were 50 ppm (wet weight) in the liver and 99 ppm 

 (wet weight) in the kidney. Cadmium residues in verteSrate 

 kidney or 1 i ver that exceed 1 ppm ( wet weight ) or 2 ppm whole 

 body (wet weight) should be viewed as evidence of probable 

 cadmium contamination (Eisler, 1985). Taylor et al. (1989) 

 recommended that additional studies be conducted on cadmium 

 contamination since levels exceed the safe levels of human 

 consumption. 



Under the auspices of a cooperative program between the 

 US and USSR, we conducted this study in order to help address 

 the above issues. During the Third Joint US-USSR Bering & 

 Chukchi Seas Expedition our purpo.se was to determine baseline 

 concentrations of arsenic, cadmium, cobalt, copper, lead, 

 manganese, and mercury in the sediment. Cadmium, arsenic, 

 lead, and mercury were determined in biota. Trace metal 

 results obtained by sediment analysis, unlike seawater analysis, 

 are generally well above the analytical detection limit and 

 contamination risks of the sediments from sample handling are 

 insignificant (Szefer, 1988). Sediment data are, therefore, 

 utilized as a tool for assessing sources and distribution of some 

 elements in aquatic environments. We investigated trace 

 metals in biota to determine if lower trophic organisms 

 bioaccumulate these metals. This may explain high 

 concentrations of cadmium in walruses further up the food 

 chain. On this expedition we collected bivalves (Nuculoidae). 

 hermit crabs (Paguridae), sea urchins (Strongylocentrotidae). 

 shrimp ( Pandalidae), neuston, zooplankton, and phy toplankton. 



Materials and Methods 



Samples were collected from the Bering and Chukchi Seas 

 while aboard the research vessel Akademik Korolev from 

 26 July to 2 September 1988. The stations were determined by 

 the chief scientists from both the US and Soviet sides and the 

 samples were collected opportunistically from each station. 

 The stations sampled are shown in the preface to this book and 

 the numbering corresponds to that shown in this figure. The 

 zooplankton and phytoplankton were collected by net tows 

 performed by the Russian scientists and described in 

 Chapter 5 (this volume). The neuston samples were collected 

 by Soviet scientists using a special surface trawl also described 

 elsewhere in this text. Samples were placed in chemically 

 cleaned I-Chem jars (I-Chem Research Inc., New Castle, 

 Delaware). The excess water was decanted and the samples 

 stored frozen until they were prepared for trace metal analyses. 



A bottom trawl, designed and operated by Soviet scientists, 

 was used to obtain the benthos samples (shrimp, crabs, bivalves, 

 and urchins). These samples were either placed in I-Chem jars 

 or, for larger samp' .>, placed in plastic Whirl-pak bags, and 

 frozen for storage. 



The sediment samples were obtained using a 30 cm- box 

 corer provided by Texas A&M University. Surface layers 

 (0-2 cm) of each sediment sample from the box corer were 

 scooped with a teflon spatula and placed directly into precleaned 

 I-Chem jars. The samples were frozen until trace metal 

 analysis. 



Analysis 



Sediment 



Sediment samples for arsenic, cadmium, cobalt, copper, 

 lead, and manganese were digested as described by Krynitsky 

 ( 1987), with modifications for the above metals. A 2.0 g (wet 

 weight ) aliquot was placed into a 50 ml polypropylene centrifuge 

 tube and 5.0 ml of nitric acid and 0.5 ml of 30% hydrogen 

 peroxide were added. The Krynitsky method was modified in 

 that 5 ml of hydrofluoric acid were added in order to free the 

 analytes from the silicates contained in sediments. The samples 

 were allowed to digest for 2 h in a hot water bath at 90°C 

 (Krynitsky, 1987). After digestion, the samples were diluted, 

 shaken, and centrifuged prior to analysis. 



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