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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Dissolved organic carbon characteristics in boreal streams in a forest-wetland gradient during the transition between winter and summer
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Dissolved organic carbon characteristics in boreal streams in a forest-wetland gradient during the transition between winter and summer

机译：冬夏过渡期森林湿地中北方河流的溶解有机碳特征

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摘要

The character and quantity of dissolved organic carbon (DOC) were studied in nine small boreal streams and adjacent soils during two years, with focus on the spring snowmelt period. The streams cover a forest-wetland gradient, spanning from 0% to 69% wetland coverage. Lower values of the absorbance ratio measured at 254 nm and 365 nm (A254/A365), in both soil plots and streams, indicated that wetland-derived DOC had higher average molecular weight than forest DOC. Higher SUVA254 (DOC specific ultraviolet absorption at 254 nm) in wetland runoff indicated more aromatic DOC from wetlands than forests. During low flow, the stream DOC character was sensitive to the forest-wetland proportion of the catchment, and when wetland coverage exceeded 10%, the streams appeared to be dominated by wetland-derived DOC. During the spring snowmelt period, the character changed to lower molecular weight and more aliphatic DOC, particularly in streams with a high proportion of forest in the catchment. The forested soil solutions had higher A254/A365 in the surface horizons that were hydrologically activated during the high flow events, while wetland soil solution had relatively low A254/A365 at all depths. Consequently forest soils contributed more to stream DOC concentration during snowmelt that during winter low flow.
机译：在两年的时间里，研究了九种北方寒流和邻近土壤中溶解有机碳（DOC）的特征和数量，重点是春季融雪期。溪流覆盖森林湿地梯度，湿地覆盖率从0％到69％。在土壤样地和溪流中，在254 nm和365 nm（A254 / A365）处测得的吸光度比值较低，表明湿地来源的DOC比森林DOC的平均分子量更高。湿地径流中较高的SUVA254（254 nm处的DOC比紫外线吸收）表明，湿地中的芳香DOC比森林多。在低流量时，溪流DOC特征对流域的森林湿地比例敏感，当湿地覆盖率超过10％时，溪流似乎受湿地DOC的支配。在春季融雪期，其特征改变为较低的分子量和更多的脂肪族DOC，特别是在流域中森林比例高的溪流中。森林土壤溶液在高流量事件中被水文激活的地表水平具有较高的A254 / A365，而湿地土壤溶液在所有深度均具有相对较低的A254 / A365。因此，与冬季低流量期间相比，森林土壤在融雪期间对流DOC的贡献更大。

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