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MERCURY CONCENTRATIONS IN SKELETAL MUSCLE OF FISH FROM LAKE MEAD, USA, RELATED TO FISH SIZE, CONDITION, TROPHIC LEVEL, LOCATION, AND CONSUMPTION RISK
Citation:
Cizdziel, J V., T A. Hinners, J. E. Pollard, E M. Heithmar, AND C L. Cross. MERCURY CONCENTRATIONS IN SKELETAL MUSCLE OF FISH FROM LAKE MEAD, USA, RELATED TO FISH SIZE, CONDITION, TROPHIC LEVEL, LOCATION, AND CONSUMPTION RISK. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 43(3):309-317, (2002).
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:
In this first large-scale study of mercury (Hg) in Lake Mead, USA, the nation's largest man-
made reservoir, total-Hg concentrations were determined in the skeletal muscle of 339 fish collected during the Fall of 1998 and the Spring of 1999. Five species of fish representing a range of trophic levels and the take's major game fish were studied. As expected, Hg generally increased with trophic level and fish size. Median Hg concentrations in ng/g wet mass, were 277, 168, 160, 75, and 8 for striped bass (Roccus saxitilis), channel catfish (Ictalurus punctatus), largemouth bass (Micropterus salmoides), bluegill (Lepomis macrochius) and blue tilapia (Oreochromis aureus), respectively. In general fish from Las Vegas Bay had the lowest Hg concentrations, possibly a result of biodilution during a lean-food season) were inversely correlated (rl = 0.80, p < 0.0001) with a fish-condition factor, which reflects overall nutritional status. This is consistent with "starvation-concentration;" whereby, Hg in fish muscle is lost at a slower rate than the overall muscle mass. The median concentration found for striped bass in this study corresponds to a risk-based consumption limit of three 8-oz (227g) meals per month for the general population.