美国小阿肯色河流域农业非点源污染物的时空分布规律

Spatiotemporal Distribution of Agricultural Non-point Source Pollutants in the Little Arkansas River Watershed in the United States

通过对美国小阿肯色河流域农业非点源污染物在时空上的动态变化规律的研究,分析了主要污染物的发生规律,以期为国内此类污染物在流域尺度上的分析研究及后期治理提供指导。取样点布置在小阿肯色河主河道的上、中、下游共3处,并实时观测取样点的降水和流量,并定期观检测水质参数:总氮、总磷和Atrazine浓度。结果表明:流域中农业作物种植面积、降水强度、历时是影响水质参数的主要因素。全流域总氮、总磷峰值浓度都出现在河流下游,且总氮、总磷的流失量丰水年约为枯水年的2倍。Atrazine浓度峰值出现在中游,且浓度年均值也是中游高于上游和下游。观测期间,全流域的总氮、总磷浓度值较高,且Atrazine浓度均高于3μg/L的临界值,需引起足够重视,并确定和实施最佳管理措施(BMPs)以治理流域内的农业非点源污染。

The role of spatiotemporal distribution of agricultural non-point source pollutants, including total nitrogen （TN）, total phosphorus （TP） and Atrazine in the Little Arkansas River watershed in the United States were monitored and analyzed, in order to provide guidance for the analytical investigation and further treatment of similar pollutants at a watershed scale in our country. The three sampling sites along the main stream of the river were located in upstream, midstream, and the outflow of the watershed. The rainfall and flow rates were monitored in real time and the water quality parameters of TN, TP and Atrazine concentrations were periodically detected. The results showed that： the factors most influencing all of the water quality parameters were the crop plant area in the watershed and the rainfall intensity and timing. The peak concentrations of both TN and TP were obtained in the lower portion of the watershed, and the loss amount of TN and TP in rainy year was about twice as much as that in drought year. Whereas, the most Atrazine lost occurs in the midstream portion of the watershed. During the period of observation, there was a large amount of TN and TP lost throughout the watershed and the Atrazine concentration was above the critical value of 3 μg/L, which should be paid enough attentions. It was suggested that the best management practices （BMPs） should be implemented to reduce the agricultural non-point source pollutants.