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Citation. Grigal, D. F.; Nater, E. A.; Homann, P. S. 1994. Spatial distribution patterns of mercury in an east-central Minnesota landscape. Pages 305-312 in C. J. Watras, and J. W. Huckabee, Eds., Mercury Pollution: Integration and Synthesis. Lewis Publishers, Boca Raton, Florida. Presented at the International Conference on Mercury as a Global Pollutant, Monterey, CA, May 31-June 4, 1992. CRC Press, Inc., Boca Raton, Florida. [1061 LTER]
Abstract. We investigated total mercury (Hg) distribution in relation to forested slope position and to vegetation cover type, ranging from abandoned agricultural field to mature forest, at Cedar Creek Natural History Area in east-central Minnesota. Mean concentration of Hg was 94 ng g^-1 in the organic layer at the soil surface, 20 ng g-' in the 0 to 10 cm soil layer, and 8 ng g^-1 in the 10 to 50 cm soil layer. Distribution of Hg across the landscape was significantly related to cover type, with more Hg present in surface soils under forests than in fields. Mercury concentration and mass were related to levels of soil organic matter, and were therefore also related to the time when fields had been abandoned from agriculture and the resulting period of organic matter accumulation. Surface soils in forests are enriched in Hg relative to nitrogen compared to those in fields; processes that affect the variation of Hg with soil organic matter differ in those systems. The Hg concentration in the 10 to 50 cm soil layer was assumed to be a measure of background levels in the uniform soil parent material, and net increase of Hg on the landscape was calculated. Lowest net increase was in fields, 0.3 mg m 2, and highest was in forests, 2.4 mg m 2; net increase in transitional vegetation was also low (0.7 mg m 2), These quantities are comparable to those we have measured in forest soils across the Great Lakes States. Because terrestrial landscapes are the receptors for the majority of Hg deposited from the atmosphere, the accumulation and transport of Hg in those landscapes merits further study.