|Balogh, S. - METRO COUNCIL ENV. SERV.|
|Nater, E. - UNIVERSITY OF MINNESOTA|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 4, 1996
Publication Date: N/A
Technical Abstract: The transport and fate of Hg in biosolids-amended agricultural watersheds needs to be evaluated in order to establish management practices which allow utilization of waste water nutrients while minimizing potential risks to the environment and to human health. The objective of this study was to investigate the fate of Hg in a cultivated watershed following 20 years of consecutive biosolids applications. The study site was a continuously cultivated, terraced watershed that received annual biosolids applications between 1974 and 1993. Mercury was not determined on biosolids samples collected at the time of application, but analysis of the stored, freeze- dried samples showed that biosolids Hg concentrations during the 20 year study ranged from 12.4 mg kg**-1 at the start to 2.4 mg kg**-1 near the end. Soils and runoff were collected from three treatment areas in the watershed that received cumulative biosolids loadings of 0, 87, and 224 Mg ha**-1. Mercury concentrations in soils that received the 224 Mg ha**-1 rate were 17 to 24 times greater than background levels. Horizontal and vertical redistribution of Hg in biosolids-amended soils was investigated. Mercury concentrations in runoff samples from biosolids-amended terraces were 1 to 3 times higher than in runoff from the control terrace. Accumulation of Hg in the watershed's runoff storage lagoon was also investigated.