中文摘要：

水体富营养化是一个全球性的问题,中国也面临严重威胁.目前,中国的水体富营养化研究主要集中在湖泊和水库,对河流的研究极少.根据大型底栖无脊椎动物的群落结构对营养盐胁迫的响应,运用非参数转变点分析方法计算西苕溪上游营养盐浓度突变点.结果表明：总氮和总磷的突变点分别为1.409mg·L^-1和0.033～0.035mg·L^-1.参照点的总氮和总磷浓度基本都低于阈值,城市干扰点则全部高于阈值,而当总氮和总磷超过各自阈值时会导致大型底栖无脊椎动物群落结构的严重退化.通过建立与水生生物群落结构有关的水体营养盐标准,可充分发挥生物监测在水环境管理中的作用,为计算水体中总氮和总磷的最大日负荷总量提供科学数据.

英文摘要：

Water eutrophication is a global problem,and one of the major environmental problems in China.At present,its studies in China are mainly focused on lakes and reservoirs,whereas a few on rivers.Based on the stress-response of benthic macroinvertebrate assemblages to water nutrients,we used the nonparametric deviance reduction（change point analysis）to compute the breakpoints of nutrients concentrations,in the upper reaches of Xitiao Stream in Zhejiang.The results indicated that the breakpoints of total nitrogen（TN）and total phosphors（TP）were 1.409 mg·L^-1 and 0.033-0.035 mg·L^-1,respectively.The TN and TP concentrations at reference sites were lower,while those at urban sewage-polluted sites were higher than the thresholds.In latter case,a serious degradation of benthic macroinvertebrates assemblages could be induced.To establish water nutrients criteria with relation to aquatic organisms would make the biological monitoring play a full role in water management,and provide scientific data to estimate the total maximum daily load（TMDL）of TN and TP in water body.