污染物在农田溪流生态系统中的动态变化  

A study on nitrogen transport in a farmland stream in Liuchahe watershed

作　　者：毛战坡[1] 尹澄清[1] 王雨春[1] 付强[1] 方杨[2] 汪海波[2] 白颖[2] 

机构地区：[1]中国科学院生态环境研究中心环境水化学国家重点实验室,北京100085 [2]合肥市环境监测站,合肥230031

出　　处：《生态学报》2003年第12期2614-2623,共10页Acta Ecologica Sinica

基　　金：国家自然科学基金资助项目 (4 0 1 71 0 0 3 )~~

摘　　要：氮是地表水体发生富营养化的主要因子 ,河流系统是氮输出的主要运移通道 ,养分在河流生态系统中的持留和趋向控制着污染物的输出。以巢湖流域一个受人为活动严重影响的农田源头溪流——六岔河为研究对象 (包括 4个渠道型、1个水塘型和 3个河口型断面 ,对应长度分别为 1 .3km、0 .1 5 km和0 .36km) ,设置 9个监测点研究总氮 ( TN)、硝酸盐 ( NO3- N)、氨态氮 ( NH+4 - N)和总悬浮物 ( TSS)在溪流生态系统中的持留 ,评价人为严重干扰下的农田溪流生态系统在非点源污染物运移中的生态功能。结果表明 :TN、NO3- N、NH+4 - N和 TSS在溪流中的持留、释放受溪流的河流形态影响 ,水塘型和河口型断面是污染物持留的主要区域 ;TN、NO3- N、NH+4 - N和 TSS在水塘型和河口型断面内的持留量分别占溪流持留量(基流、径流持留量的和 )的 61 %、47%、75 %和 5 6%。降雨 -径流过程中发生的持留是污染物持留的主要部分 ,TN、NO3- N、NH+4 - N和 TSS的持留量分别占溪流持留量的 93%、97%、89%和 96% ;渠道型断面是溪流最主要的内在污染源 ,污染物释放量占溪流释放量的 90 %以上 ;受水塘型断面出口处的水坝影响 ,位于水塘前的渠道型断面在基流和降雨 -径流过程中均有效地持留污染物 。The spatial dynamics of nutrient and suspended solids were investigated for two years in a 1.8 km agricultural headwater stream, located by Chaohu Lake, southeastern China. The stream form was greatly modified by human activities. The stream could be divided into 4 channelized reaches (1.3 km), a pond reach (0.15 km) and 3 estuary reaches (0.36 km). It was found that retention of total nitrogen (TN), nitrate (NO_3-N), ammonium (NH^+_4-N) and total suspended solids (TSS) predominantly occurred in the pond reach and estuary reaches. TN, NO_3-N, NH^+_4-N and TSS retained in the pond reach and estuary reach accounted for more than 50% of those retained in whole stream. The retention mostly happened in the rain-runoff events and it was 13 to 27 times than that in baseflow. The results showed that the channelized reach was the most important source for pollutant release under either runoff or baseflow conditions, and it accounted for more than 90% of whole stream release. There was a high spatial variability of nutrient dynamics in different channelized reaches. The channelized reach directly discharging into the pond did always retain nutrient and TSS under base flow and runoff conditions, whereas the other channelized reaches performed differently in different hydrological conditions. The high spatial dynamics of nutrient and TSS in the stream was resulted form anthropogenic disturbance of the agricultural headwater stream, such as channelization and excavation, it suggested that would be expected to decrease the capacity of nutrient retention in the stream.

关 键 词：释放 持留 养分 空间动态 溪流形态 生态系统 污染物 农田 动态变化 

分 类 号：X50[环境科学与工程—环境工程]