A mass balance model for mercury in Lake Champlain was developed in an effort to understand the sources, inventories, concentrations, and effects of mercury (Hg) contamination in the lake ecosystem. To construct the mass balance model, air, water, and sediment were sampled as a part of this project and other research/monitoring projects in the Lake Champlain Basin. This project produced a STELLA-based computer model and quantitative apportionments of the principal input and output pathways of Hg for each of 13 segments in the lake. The model Hg concentrations in the lake were consistent with measured concentrations. Specifically, the modeling identified surface water inflows as the largest direct contributor of Hg into the lake. Direct wet deposition to the lake was the second largest source of Hg followed by direct dry deposition. Volatilization and sedimentation losses were identified as the two major removal mechanisms. This study significantly improves previous estimates of the relative importance of Hg input pathways and of wet and dry deposition fluxes of Hg into Lake Champlain. It also provides new estimates of volatilization fluxes across different lake segments and sedimentation loss in the lake.

Physical, chemical, and biological data were collected during 1994-95 in the Freezeout Lake area of west-central Montana as a follow-up to a 1990-92 detailed study of the extent, magnitude, sources, and biological effects of selenium and other constituents associated with irrigation drainage in the Sun River Irrigation Project. The 1990-92 study determined that return flow from irrigated glacial-lake deposits is the primary source of selenium to wetlands in the Freezout Lake Wildlife Management Area. Data were collected in 1994-95 to provide a basis to better understand (1) selenium distribution, mobilization processes, and transport rates in irrigated land underlain by glacial-lake deposits that drain into wetlands of Pond 5 and the southern part of Freezeout Lake, and (2) selenium distribution, toxicity risks, and accumulation in the wetlands and biota. This report presents data for selenium and other potentially toxic constituents in solid-phase, water, and biological media. Physical and chemical data are reported for soil, drill cores, soil moisture, ground water, surface water, and bottom sediment. Biological data include selenium residues measured in aquatic plants, aquatic invertebrates, fish, water-bird eggs, and water-bird livers.

We assessed the effects on fish of lead (Pb) released to streams by smelters located in Trail, BC (Canada), E. Helena, MT, Herculaneum, MO, and Glover, MO. Fish were collected by electrofishing from sites located downstream of smelters and from reference sites. Blood from each fish was analyzed for delta-aminolevulinic acid dehydratase (ALAD) activity and hemoglobin (Hb), and samples of blood, liver, or carcass were analyzed for Pb, zinc (Zn), or both. Fish collected downstream of all four smelters sites had elevated Pb concentrations, decreased ALAD activity, or both relative to their respective reference sites. At E. Helena, fish from the downstream site also had lower Hb concentrations than fish from upstream. Differences among taxa were also apparent. Consistent with previous studies, ALAD activity in catostomids (Pisces: Catostomidae-northern hog sucker, Hypentelium nigricans; river carpsucker, Carpiodes carpio; largescale sucker, Catostomus macrocheilus; and mountain sucker, C. platyrhynchus) seemed more sensitive to Pb-induced ALAD inhibition than the salmonids (Pisces: Salmonidae-rainbow trout, Oncorhynchus mykiss; brook trout, Salvelinus fontinalis) or common carp (Cyprinus carpio). Some of these differences may have resulted from differential accumulation of Zn, which was not measured at all sites. We detected no ALAD activity in channel catfish (Ictalurus punctatus) from either site on the Mississippi River at Herculaneum. MO. Our findings confirmed that Pb is released to aquatic ecosystems by smelters and accumulated by fish, and we documented potentially adverse effects of Pb in fish. We recommend that Zn be measured along with Pb when ALAD activity is used as a biomarker and the collection of at least 10 fish of a species at each site to facilitate statistical analysis.

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This report presents information on the two wetlands in the Johnson Field Area through the end of 1986. This includes a literature review of passive mine drainage treatment technology; a presentation of wetland design and construction methods; and a comprehensive presentation of those data recorded through the end of 1986.The results are discussed and recommendations made.The intent of the project considered in this report was to develop two experimental wetland ecosystems and evaluate their effectiveness at removing metal ions and modulating low pH values. The limited data available prevents a conclusive analysis of many of the factors affecting wetland performance.The time of year when the methods were constructed, inadequate time for wetland establishment, and inconsistent monitoring impacted analysis.However, continued monitoring will allow for a more complete analysis of wetland performance to be made in the future. Experience from this project has already provided for design improvements which can be included in future wetlands projects.