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Determination of heavy metal concentrations in soil sediment and mussels of eastern North Dakota river systems.

Introduction

In Eastern North Dakota, it is known that Cadmium, (Cd), and other heavy metals are naturally present within the soil possibly due to the glacial history of the area (Stoner et al., 1998). Cadmium is a known endocrine disruptor and often bioaccumulates within organisms having toxic side effects. We are examining the levels of Cd and other trace metals in river sediments from the Sheyenne and Pembina Rivers in eastern ND and mussel tissue samples collected from the Sheyenne River.

Methods

We collected 52 mussels that encompassed 8 native species. Mussels were chosen for a biological indicator because of the mussel's close proximity with stream substrate during their lifetime. They were also chosen for their large size and abundance within the study area. Soft tissues of these mussels were dissected after a 24 hour depuration period to allow gut contents to empty. Dissections were carried out using non-metallic instruments in order to eliminate contamination of the tissue samples with a foreign metal. Mussel tissues were then dried to a constant weight and digested according to EPA method 3052 while dried soil samples were digested with EPA method 3051A. Blanks were prepared using acid digestions of concentrated analytical grade nitric acid that was diluted to a constant volume. Controls for heavy metals were prepared using mussel tissues that have known concentrations of trace elements that were obtained from the National Institute of Standards & Technology. Samples were sent to Activation Laboratories in Ontario, Canada, to be analyzed by inductively coupled plasma mass spectrometry, (ICP-MS). Fifty-nine different elements were analyzed by this method.

Results

In general, heavy metals were slightly higher in the Pembina River sediments. For example, the Cd levels in sediment from the Pembina sampling sites were more than 3 times greater than the samples from the Sheyenne River. The average levels for the Sheyenne sediment samples were 0.247 ppm Cd (n=14) while the average for the Pembina was 0.847 ppm (n=13). This higher value for the Pembina is congruent with the data of Stoner et al. (1998). Other metals showed less of a difference, but were still slightly higher in the Pembina. The average for Zinc in sediment from the Sheyenne sites was 81.81 ppm (n=14), while for the Pembina it was 95.08 ppm (n=13). The

Lead levels in the Sheyenne was 11.07 ppm (n=14), and 12.89 for the Pembina (n=13). In examining the heavy metal concentrations for the mussel tissue there was one set of data that stood out. The White Heel Splitter, Lasmigona complanata, had higher Cd levels at a degree between 8 to 13 times greater than all other species. On average the Cd levels for the White Heel Splitter was 124.2 ppb (n=5). The average for Cd in the Plain Pocketbook (Lampsilis cardium) was 9.6 ppb (n=5), 9.92 ppb (n=15) for Three Ridge (Amblema plicata), 14.8 ppb (n=6) for Wabash Pigtoe (Fusconaia flava), and 12.41 ppb (n= 10) for the Fat Mucket (Lampsilis silquoidea). Overall the average for all species other than the White Heel Splitter was 11.4 ppb (n=52).

Conclusions

The White Heel Splitter had much higher levels of cadmium in its' tissues than the other species of mussels. This would seem to indicate that this mussel can sequester Cd. The populations of this mussel are healthy within the Sheyenne River so this level of Cd does not seem to be having a negative effect on the White Heel Splitter. We would like to examine what physiological mechanisms, e.g. heat shock proteins and/or metallothionens, the mussels may be utilizing in sequestering Cd.

References

Stoner, J. D., D.L. Lorenz, R.M. Goldstein, M.E. Brigham, and T.K. Cowdery. 1998. "Water Quality in the Red

River of the North Basin Minnesota, North Dakota, and South Dakota, 1992-95." U.S. Geological Survey Circular 1169.

This work is supported by NIH grant P20RR016741 from the NCRR.

Andrew J. Hager *, Louis M. Wieland, Andre W. DeLorme.

Department of Biology, Macroinvertebrate Laboratory, Valley City State University, Valley City, ND.
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Article Details
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Title Annotation:COMMUNICATIONS--UNDERGRADUATE
Author:Hager, Andrew J.; Wieland, Louis M.; DeLorme, Andre W.
Publication:Proceedings of the North Dakota Academy of Science
Article Type:Technical report
Geographic Code:1U4ND
Date:Apr 1, 2008
Words:686
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