Biodegradability of Dissolved Organic Matter in Forest Throughfall, Soil Solution, and Stream Water

作者：Robert G. Qualls, Bruce L. Haines · 发表于：Soil Science Society of America Journal · 年份：1992 · DOI：10.2136/sssaj1992.03615995005600020038x · 被引用次数：626 · 研究领域：Soil and Water Nutrient Dynamics、Urban Stormwater Management Solutions、Freshwater macroinvertebrate diversity and ecology

Abstract High concentrations of dissolved organic matter (DOM) were leached into rainwater passing through the canopy and forest floor of an oak ( Quercus spp.)‐hickory ( Carya spp.) forest in the southern Appalachian Mountains. More than 95% of this dissolved organic C (DOC) and N (DON) was removed as water percolated through the soil profile and left the ecosystem in stream water. Our objective was to examine the importance of decomposition in the removal of DOC and DON. Samples of DOM from throughfall, forest floor water, soil water from A and B soil horizons, and stream water were all adjusted to a common initial DOC concentration, inoculated with soil and stream microbes, and incubated in solution for 134 d. In general, only 14 to 33% of the DOC in forest floor, soil solution, and stream samples decomposed during the incubation. The relative order of average decomposition of DOC from the various strata was, from fastest to slowest; throughfall, Oi horizon (forest floor), Oa horizon (forest floor), B horizon, stream, AB horizon, isolated fulvic acid, and upper A horizon. In short, biodegradability of DOM in the ecosystem profile declined vertically from throughfall to the A horizon and then increased with depth. The DON generally did not decay faster than the DOC — results consistent with the idea that hydrolysis of organic N is linked to mineralization of DOC rather than occurring selectively in response to the biochemical need for N. Throughfall DOM could be decomposed ...