基于降雨事件监测的非点源污染对灞河水质的影响

在对灞河马渡王水文站断面5次降雨事件过程和2次非洪水过程监测的基础上,分析了灞河流域非点源污染对灞河水质的影响.结果表明:降雨过程期间,COD、总氮、氨氮、硝氮、亚硝氮、总磷指标监测平均值均小于非洪水期监测平均值.各指标负荷输移速率随时间的变化趋势和径流量变化趋势大体相同,即先逐渐增大达到峰值,再逐渐变小;各指标浓度随时间的变化规律大致为:COD、硝氮、总氮浓度先增大后减小;亚硝氮为先减小后增大,总磷的变化规律不明显.总氮、硝氮的浓度峰和负荷输移速率峰均接近或滞后于流量峰;COD的浓度峰接近或滞后于流量峰,而负荷输移速率峰接近或超前于流量峰;总磷、氨氮的浓度峰和负荷输移速率峰均接近或超前于流量峰;而亚硝氮的浓度峰变化规律不明显,负荷输移速率峰接近或超前于流量峰.采用平均浓度法计算了各指标的非点源污染平均浓度及负荷:2009年灞河流域马渡王断面COD、总氮、氨氮、总磷的非点源污染负荷分别为8707.28,723.63,245.52,43.07t.2009年灞河流域马渡王断面NSP负荷COD、总氮、氨氮、总磷所占总负荷相应的比例分别为31.86%、32.69%、42.21%、34.42%.由此可见,非点源污染在灞河水污染中占有较大比重,其对于灞河水质的影响不容忽视.

Impact of nonpoint source pollution on water quality of the Bahe River based on rainfall events monitor

Based on the 5 rainfall processes and 2normal discharge events monitored from July to December in 2009at the Ma du-wang section on the Bahe River, impact of nonpoint source pollution (NPS) on water quality of the Bahe River was analyzed. The results indicate that: (1) concentrations of COD, TN, NH3-N, NO3--N, NO2--N and TP in the rainfall processes were lower than those in normal discharge events. (2) The load transport rate of each pollutant gradually increased up to peak value and then started to drop, which was in accordance with the process of flow change. Concentrations of COD, NO3--N and TN increased initially and then decreased, while those of NH3-N and NO2--N decreased first and then increased, change pattern for concentration of TP was not obvious. The peaks of concentration and load transport rate of TN and NO3--N occurred either close or behind the flow peak, while those for TP and NH3-N in the opposite trend. COD concentration peaked close or behind the flow peak, but its load transport rate peaked prior to the flow peak. Changes for NO2--N concentration werenot obvious and its load transport rate peak was close or prior to the flow peak. (3) The estimation of NPS pollution load by mean concentration method indicated that NPS pollution load of COD, TP, TN and NH3-N of the Bahe River in the year of 2009were 8707.28t, 43.07t, 723.63t and 245.52t. (4) The NPS pollution load proportions of COD, TP, TN and NH3-N of the Bahe River in the year of 2009 were 31.86%, 34.42%, 32.69% and 42.21%. Therefore, NPS pollution accounted for a large proportion of the total pollution loads of the Bahe River, which shouldn’t be ignored.