Hydrologic flowpaths influence inorganic and organic nutrient leaching in a forest soil

被引:38
作者
Asano, Yuko
Compton, Jana E.
Church, M. Robbins
机构
[1] US EPA, Western Ecol Div, Natl Hlth & Environm Effects Lab, Corvallis, OR 97333 USA
[2] Univ Tokyo, Grad Sch Agr & Life Sci, Bunkyo Ku, Div Res,Univ Forests, Tokyo 1138657, Japan
基金
日本学术振兴会;
关键词
soil solution; throughfall; dissolved organic nitrogen; dissolved organic carbon; nitrate; cations; hydrogen isotopes; lysimeters; flowpaths; contact time;
D O I
10.1007/s10533-006-9036-4
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
Hydrologic pathways through soil affect element leaching by determining the relative importance of biogeochemical processes such as sorption and decomposition. We used stable hydrogen isotopes of water (delta D) to examine the influence of flowpaths on soil solution chemistry in a mature spruce-hemlock forest in coastal Oregon, USA. Soil solutions (50 cm depth, n = 13) were collected monthly for 1 year and analyzed for delta D, major ions and dissolved organic carbon (DOC) and nitrogen (DON). We propose that the variability of delta D can be used as an index of flowpath length and contact time. Throughfall variability in delta D was much greater than soil solution variability, illustrating that soil solution integrates the variation in inputs. Lysimeters with greater variation in delta D presumably have a greater proportion of flow through rapid flowpaths such as macropores. The variation in soil solution delta D for individual lysimeters explained up to 53% of the variation in soil solution chemistry, and suggests that flowpaths influence leaching of some constituents. Soil solutions from lysimeters with greater delta D variation had higher DOC and DON (r(2) = 0.51 and 0.37, respectively), perhaps because transport via macropores reduces interaction of DOM with the soil matrix. In contrast, nitrate concentrations were highest in lysimeters with a small variation in delta D, where long contact time and low DOC concentrations may yield higher net nitrification. Our results demonstrate the utility of stable isotopes to link flowpaths and soil solution chemistry, and illustrate how the spatial complexity of soils can influence ecosystem-level nutrient losses.
引用
收藏
页码:191 / 204
页数:14
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