•  
  •  
 

Publication Date

1989

Keywords

Fishes--Effect of chemicals on; Fishes--Effect of heavy metals on

Abstract

ABSTRACT-High mercury concentrations in fish of some Minnesota lakes and rivers were first noted in 1971. Major anthropogenic sources of mercury to Minnesota rivers generally have been identified and controlled, but it has been difficult to identify mercury sources to remote northeastern Minnesota lakes containing fish with elevated mercury levels. Analysis of sediments from these lakes suggests that mercury deposition has increased by a factor of about 3.5 since white settlement in the state. Because the increase is spatially constant across northeastern Minnesota, atmospheric pollution appears to be responsible for the increase. Given that fish mercury varies considerably among lakes, local environmental processes apparently control the conversion of inorganic mercury into the methylmercury found in fish. Mercury levels in Minnesota fish are related to wa~er chemistry, which in turn is influenced by watershed geology. Fish from lakes in limestonerich watersheds are less likely to have high mercury levels than lakes in low-alkalinity regions. lakes with colored water are more likely to contain fish with high mercury levels. Trend analysis shows that mercury levels in fish increased significantly between the 1930s and 1980s (comparison between museum specimens and recent samples) and between the 1970s and 1980s. Rates of increase are highest in low-alkalinity lakes.

First Page

103

Last Page

109

Included in

Biology Commons

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.