Topographic Controls of Nitrogen, Sulfur, and Carbon Transport from a Tolerant Hardwood Hillslope

ISSN： 1567-7230

Source： Water, Air and Soil Pollution: Focus, Vol.2, Iss.1, 2002-01, pp. : 63-80

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Abstract

The lateral down-slope movement of water, NO_3^-, NH_4^+, SO_4^2-, H^+ and DOC through an ablation till was examined from 1987 to 1990 for a one hectare soil catena on a steep hillslope with uniform forest cover at the Turkey Lakes Watershed (TLW), Ontario, Canada. Natural variation in the export of nutrients from the soil profile via soil water to Little Turkey Lake was assessed in relation to nutrient distribution in soil at different topographic positions. Subsurface throughflow exhibited dramatic differences in nutrient concentrations and fluxes with slope position, largely reflecting that of the soil horizons through which the water passed. Greater NO_3^-, SO_4^2-, and DOC concentrations in subsurface water in the upper, well-drained hillslope were a reflection of enrichment by contact with more acidic, more developed podzols, and more favorable soil physical and biological conditions for NO_3^- retention in solution. Nutrient inputs to the lake were strongly influenced by increased down-slope transport of water, and increased SO_4^2-, N, and C retention in wetter, less-developed podzolic soils that characterize lower slope positions. An understanding of water movement and soil development variation with topographic position was required to accurately estimate nutrient budgets for steep slopes at TLW.