Total mercury concentrations in lakes and fish of western Maryland, USA.

The purpose of this study was to quantify total mercury concentrations in three species of fish in three lakes of western Maryland: Piney Creek reservoir, Deep Creek Lake, and Lake Habeeb. We measured total mercury concentrations in water from each lake and muscle tissue from 119 fish collected in fall 2000: 15 largemouth bass (Micropterus salmoides), 15 yellow perch (Perca flavescens), and 15 bluegill (Lepomis macrochirus) from the Piney Creek reservoir; 15 largemouth bass, 15 yellow perch, and 14 bluegill from Deep Creek Lake; and 15 largemouth bass and 15 bluegill from Lake Habeeb. Average total mercury concentrations (+/- SD) in surface waters were 0.96 +/- 0.03 ng L(-1) for the Piney Creek reservoir, 0.56 +/- 0.07 ng L(-1) for Deep Creek Lake, and 0.40 +/- 0.05 ng L(-1) for Lake Habeeb. These water quality differences were sometimes reflected in the total mercury concentration in fish muscle tissue. Total mercury concentrations in bluegill (0.05 +/- 0.02 microg g(-1)) and largemouth bass (0.10 +/- 0.03 microg g(-1)) from Lake Habeeb were significantly (p < 0.001) lower than the total mercury concentrations in bluegill and largemouth bass from the Piney Creek reservoir (bluegill: 0.13 +/- 0.04 microg g(-1) and largemouth bass: 0.37 +/- 0.18 microg g(-1)) and Deep Creek Lake (bluegill: 0.11 +/- 0.04 microg g(-1) and largemouth bass: 0.30 +/- 0.09 microg g(-1)). Yellow perch from the Piney Creek reservoir had significantly higher total mercury concentrations than yellow perch from Deep Creek Lake (0.20 +/- 0.08 microg g(-1) versus 0.13 +/- 0.04 microg g(-1)). In contrast, total mercury concentrations in largemouth bass from the Piney Creek reservoir and Deep Creek Lake were not significantly different. With the exception of largemouth bass from Lake Habeeb and yellow perch from Deep Creek Lake, there were relatively strong (r(2) > 0.39-0.79) log-log relationships between the size (weight and length) of the fish and total mercury concentrations in muscle tissue. The largest largemouth bass (> 800 g and > 38 cm) from both Deep Creek Lake and the Piney Creek reservoir had total mercury concentrations that exceeded the consumption advisory of 0.5 microg g(-1) that is used by many states and Canada. In contrast, total mercury concentrations in largemouth bass from Lake Habeeb did not exceed this consumption advisory. Our results suggest that fish consumption advisories are needed for largemouth bass in the Piney Creek reservoir and Deep Creek Lake.

The impact of foreign graduate students on engineering education in the United States.

Surveys of chairpersons and faculty members of engineering departments of U.S. universities were conducted in the fall of 1985 to examine the relation between the high proportion of foreign graduate students and the operation and quality of engineering education in the United States. Information was obtained on admissions criteria and policies, financial aid, and the performance of U.S. and foreign students as teaching and research assistants. Overall, the survey respondents believed that foreign students are an asset and that, without them, training and research would suffer. Language and communications were the problems most frequently mentioned as adversely affecting the performance of foreign students.

Acute toxicity of nitric acid to fingerling rainbow trout (Salmo gairdneri).

The acute toxicity of nitric acid to fingerling rainbow trout was measured in 7 day bioassays at 11 degrees C. The LC50 was about pH 4.0. Fish which died at low pH (3.0-4.0) exhibited classical symptoms of acid toxicity. Comparison of our results with other toxicity measurements suggests that nitric acid is intermediate in toxicity between H2SO4 and HCl at pH 3.0 and less toxic than either acid at pH 3.3 and above.

Toadfish serum as a binder for in vitro assay of vitamin B12.

Serum from the oyster toadfish, Opsanus tau, has a binding capacity for cyanocobalamin 1,000 times greater than that of human serum. The binding follows the principle of isotope dilution in the physiologic range of vitamin B12 present in human serum. Under proper conditions of storage, this binder is stable for at least 1 year. Standard reagents and techniques used in other vitamin B12 competitive binding assays can be used with the toadfish serum binder. Toadfish serum offers potential advantages over intrinsic factor and human serum, the most commonly used binders in vitamin B12 assays.