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DISTRIBUTION OF MERCURY IN THE TISSUES OF FIVE SPECIES OF FRESHWATER FISH FROM LAKE MEAD, USA
Citation:
Cizdziel, J V., T A. Hinners, C L. Cross, AND J. E. Pollard. DISTRIBUTION OF MERCURY IN THE TISSUES OF FIVE SPECIES OF FRESHWATER FISH FROM LAKE MEAD, USA. JOURNAL OF ENVIRONMENTAL MONITORING 5(5):802-807, (2003).
Impact/Purpose:
The overall goals of the task are to apply NERL's core capability in advanced chemical science and technology for maximum benefit in estimating exposures of ecosystems and humans to chemical stressors and to identify emerging pollution concerns, in particular long-range airborne transport of contaminants. This task comprises several subtasks, each with individual objectives:
Subtask 1: screen exposures of National Park PRIMENet ecosystems to chemical stressors, identifying indications of exposure requiring further evaluation, and use these samples evaluate new analytical methods as replacements for standard methods in future assessments of ecosystem contaminant exposures.
Subtask 2: evaluate a new mercury analytical approach with superior performance on complex solid matrices such as biological tissues, and apply the approach to estimating exposure of ecosystems and humans to mercury.
Subtask 3: determine distribution patterns of chemical contaminants in the southern Sierra Nevada Range of California, investigate topographic and weather factors that may influence the distributions, and determine if a correlation exists between contaminant distributions and extirpation patterns of the mountain yellow-legged frog.
Subtask 4: provide analytical methods to measure a number of inorganic and organic arsenic species in a variety of environmental matrices, elucidate the environmental transformations undergone by organoarsenic animal-feed additives, and determine if the potential exists for substantially increased exposure of humans and aquatic organisms to arsenic.
Description:
Total mercury (Hg) concentrations were determined in seven tissues (skeletal muscle, liver,
blood, gonad, brain, gill, and heart) of 59 striped bass and four tissues (muscle, liver, blood, and
gonad) of 69 largemouth bass, 76 channel catfish, 12 bluegill, and 22 blue tilapia collected from Lake Mead, USA. Mercury levels generally increased in these tissues according to trophic level and fish length. For striped bass, mean Hg levels (ng/g, wet mass) were highest in the liver (531), followed by muscle (309),heart(186),gonad(136),brain(77),gill(52),and blood (36). Similarly, Hg levels in the catfish and tilapia also show liver > muscle > gonad > blood. In contrast, largemouth bass and bluegill had the highest levels in muscle, followed by liver, gonad, and blood. At muscle-Hg concentrations greater than about 400 ng/g, the Hg concentrations in the other tissues increase relative to the muscle. Emaciation among striped bass was correlated with elevated Hg levels in all tissues. Liver-to-muscle ratios were similar to literature values, except for tilapia with an average ratio of -1.7, which is higher than generally reported for non-piscivores.