高寒山区典型小流域河流溶解性有机碳输出的年内变化及其成因  

Intra-annual Variation of Dissolved Organic Carbon Export through Stream from an Typical Alpine Catchment in Qinghai-Tibet Plateau:Patterns and Hydrological Controls

作　　者：王烁[1] 孙自永[1,2] 胡雅璐 葛孟琰 常启昕 WANG Shuo SUN Ziyong HU Yalu GE Mengyan CHANG Qixin(School of Environment Studies, China University of Geosciences,Wuhan 430074, China Laboratory of Basin Hydrology and Wetland Eco-restoration , China University of Geosciences , Wuhan 430074, China)

机构地区：[1]中国地质大学(武汉)环境学院,湖北武汉430074 [2]中国地质大学盆地水文过程与湿地生态恢复学术创新基地,湖北武汉430074

出　　处：《安全与环境工程》2017年第2期1-7,15,共8页Safety and Environmental Engineering

基　　金：国家自然科学基金项目(91325101;91125009)

摘　　要：高寒山区河流溶解性有机碳(DOC)的输出可能有别于北极、亚北极地区,但却少有人研究。选取青藏高原黑河上游的典型高寒小流域——葫芦沟流域为研究对象,通过流域出口处河水DOC浓度的连续观测,分析了河水DOC输出的季节性变化规律,并探讨了流域水文过程对河水DOC输出的影响。结果表明:河水的DOC通量与河道径流量的变化趋势一致,从冬季至春季逐渐降低,夏季急剧增高,秋季又逐渐降低;河水DOC浓度的变化则恰好相反,冬季时最高,春季时略有下降,夏季时急剧降至最低值,秋季再次增高;河水DOC的输出主要集中在夏、秋两季,7~11月份的输出量占河水DOC年输出总量的80%。各水源和流动路径对河水贡献比例的变化是导致上述季节性差异的深层机制:在夏季,低DOC浓度的冰川融水和山区产流对径流有更高的贡献,故河水具有较低的DOC含量,但因其流量远高于其他季节,故DOC通量为全年最高;秋季至初冬,高DOC浓度的寒甸带冻土层上水对径流贡献比例逐渐增大,导致河水的DOC浓度增高;冬季时,河水全部源于秋季时储存在平原区含水层中的高DOC浓度的地下水,故河水的DOC浓度最高;春季中后期,除秋季时储存起来的地下水外,具有较高DOC浓度和极低溶解性无机碳(DIC)浓度的寒甸带融雪水对河水也有一定贡献,故河水DOC浓度变化不大,但其DIC浓度明显降低。Stream Dissolved Organic Carbon（DOC）export from alpine catchments which is expected to be different from that from the northern catchments has been poorly studied.Through the continuous measurement of the stream DOC concentrations from December 2012 to November 2013 in Hulugou catchment,an alpine catchment in the upper reaches of Heihe River in Qinghai-Tibet Plateau,this paper analyzes the seasonal variations of the stream DOC flux and discharge,and discusses the influence of the catchment hydrological process on the stream DOC export.The results show that the variation pattern of stream DOC flux is similar to that of stream discharge,both decreasing gradually from winter through spring,increasing sharply in summer,and decreasing again in autumn.Conversely,the stream DOC concentration is the highest in winter,decreases slightly through spring,then drops sharply to the lowest in summer,and increases again in autumn.About 80% of the annual DOC export occurs during the warm seasons from July to November.The lowest stream DOC concentration in summer should be ascribed to the greater contribution of glacier meltwater and rainfall-runoff from mountain areas which are depleted in DOC than that of suprapermafrost groundwater and overland flow from the alpine meadows on hills which are rich in DOC.It is opposite in autumn and early winter when the DOC concentration in stream increases gradually.During the winter,all stream water is from the groundwater that has been stored within the plain aquifer in autumn.As the groundwater is rich in DOC,the stream DOC concentration is the highest in winter.In mid-late spring,in addition to the groundwater from plain aquifer,snow meltwater from alpine meadows that is rich in DOC but depleted in Dissolved Inorganic Carbon（DIC）also contributes to the stream.Thus,the concentration of DOC in stream is constant whereas that of DIC decreases significantly.

关 键 词：高寒山区 河流 溶解性有机碳(DOC) 多年冻土 水分来源 青藏高原 

分 类 号：X143[环境科学与工程—环境科学] P641.69[天文地球—地质矿产勘探]