土地利用变化对挠力河流域可溶性有机碳输出的影响

Influence of land use change on dissolved organic carbon export in Naoli River watershed,Northeast China

采用野外采样、室内分析、GIS及统计分析相结合的方法,石开究了挠力河流域河水可溶性有机碳(DOC)浓度的季节性动态,以及年均尺度上全流域、100 m河岸带土地利用变化对河水DOC输出的影响.结果表明:基流状态下河水DOC浓度在春季、夏季显著高于秋季;有湿地存在的子流域DOC浓度的季节性动态与无湿地存在的子流域存在显著差异,且有湿地存在的子流域中DOC浓度的季节性变异与整个流域的趋势一致;年均尺度上,DOC浓度与全流域湿地以及100 m河岸带范围内的水田面积百分比呈显著正相关,而与全流域尺度的林地百分比呈显著负相关(P<0.05).表明湿地的存在是影响挠力河流域河水DOC季节性变异的重要因素;全流域的湿地以及100 m河岸带范围内的水田对其具有显著的促进作用,而林地对其有显著的减缓效应流域过去几十年的土地利用变化改变了河水DOC的平衡状况.

The present study was conducted to evaluate the influence of land use change on dissolved organic carbon（DOC） export in Naoli River watershed,Northeast China.Seasonal variation of DOC concentrations of the river water and its relationship with land use in the whole watershed and 100 m riparian zone at the annual average scale were analyzed using the method of field sampling,laboratory analysis,GIS and statistics analysis.The results showed that the concentrations of DOC under base flow conditions in spring and summer were significantly higher than that in fall in the study watershed.The seasonal trend of DOC concentrations in wetland-watersheds was similar to that in all the sub-watersheds,while significantly different from that in non-wetland watersheds.On the annual average scale,percentage of wetland in the whole watershed and paddy field in the 100 m riparian zone had positive relationship with the DOC concentration in the river water,while percentage of forest in the whole watershed had negative relationship with it（P〈0.05）.It indicated that wetland in the sub-watershed played a significant role in the seasonal variation of DOC in river water of Naoli River watershed.Wetland in the watershed and paddy field in the 100 m riparian zone significantly promoted DOC export,while forest alleviated it.Land use change in the watershed in the past few decades dramatically changed the DOC balance of river water.