Regional differences in mercury levels in aquatic ecosystems: A discussion of possible causal factors with implications for the Tennessee River System and the Northern Hemisphere

Journal Article · · Environmental Management; (United States)

DOI:https://doi.org/10.1007/BF02400859· OSTI ID:6966793

Joslin, J D ^[1]

---

1. Oak Ridge National Lab., TN (United States)

Concern about mercury pollution from atmospheric deposition has risen markedly in the last decade because of high levels of mercury in freshwater fish from relatively pristine waters. Whereas high concentrations have been found principally in Canada, the northern United States, and Scandinavia, they have also recently been observed throughout much of Florida. Recent surveys of the Tennessee River system, however, have found no locations where fish levels exceed EPA guidelines for fish consumption. This paper evaluates a number of factors that may cause certain regions in the northern hemisphere to experience unacceptable fish mercury levels while other regions do not. Relevant regional differences include: (1) Waters of the Tennessee River system are generally nonacidic (pH > 6) and well buffered, whereas 16%, 22%, and 40% of the lakes in upper Midwest, Northeast, and Florida, respectively, have acid-neutralizing capacities below 50 [mu] eq/liter. Acidity correlates highly with fish mercury levels in a number of lake surveys, and experimental manipulations of acidity have significantly raised fish mercury levels. (2) The ratio of land area to water surface area in the Tennessee Valley averages about 30, whereas it is 15 in the upper Midwest and 6 in Florida. Low ratios allow mercury in precipitation to be directly deposited to aquatic bodies, without an opportunity for the mercury to be sequestered by terrestrial ecosystems. (3) Stream organic matter concentrations in Florida, the upper Midwest, and Sweden are 2-10 times those in the Tennessee Valley. Mercury binds strongly to organic matter, and organic matter transport in runoff is a major pathway by which mercury enters aquatic ecosystems. 54 refs., 1 fig., 2 tabs.

• OSTI ID: 6966793
• Journal Information: Environmental Management; (United States), Journal Name: Environmental Management; (United States) Vol. 18:4; ISSN EMNGDC; ISSN 0364-152X
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
540320 -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (1990-)
AIR POLLUTION
AQUATIC ECOSYSTEMS
CONTAMINATION
DEPOSITION
DISTRIBUTION
ECOLOGICAL CONCENTRATION
ECOSYSTEMS
ELEMENTS
GLOBAL ASPECTS
MERCURY
METALS
POLLUTION
SPATIAL DISTRIBUTION