Abstract
Biosolids applications can significantly increase Hg concentrations in cultivated soils. The objective of this study was to quantify levels of mercury in soils and runoff from a biosolids-amended watershed. The study site was a terraced, cultivated watershed that received cumulative biosolids loadings of 0, 87, or 224 Mg ha-1 between 1974 and 1993. Snowmelt runoff samples were collected from the three treatment areas in the spring of 1995. Soils were collected along transects from the 0 and 224 Mg ha-1 biosolids treatment areas at depths of 0 to 15 and 15 to 30 cm. Mercury analysis of stored, freeze dried biosolids samples showed that Hg concentrations during the 20-year study ranged from 12.4 mg kg-1 initially to 2.4 mg kg-1 near the end. Soil Hg concentrations were elevated in the surface (0-15 cm) and subsurface (15-30 cm) of the 224 Mg ha-1 biosolids-treated terrace relative to the control. Mercury concentrations in the 0- to 15-cm soil depth ranged from 30 to 50 μg kg-1 for the control terrace and 180 to 390 μg kg-1 for the 224 Mg ha-1 biosolids-treated terrace. Concentrations were lower in the 15- to 30-cm depth. Total Hg concentrations in snowmelt from the control terrace ranged from 9.2 to 27.9 ng L-1 and 19.8 to 44.8 ng L-1 for the biosolids-treated terraces. Most Hg was associated with particulates > 0.45 μm. Mercury concentrations were elevated in grass tissue growing near the watershed's runoff lagoon.
Original language | English (US) |
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Pages (from-to) | 2173-2179 |
Number of pages | 7 |
Journal | Journal of Environmental Quality |
Volume | 30 |
Issue number | 6 |
DOIs | |
State | Published - 2001 |