北运河下游典型河网区水体中氮磷分布与富营养化评价

选择北运河下游典型河网区(闸坝多、水流慢和湖库化)为研究对象,通过为期1 a的水质监控,阐述了河网区氮、磷的时空变化特征,并利用对数型幂函数普适指数公式对其水体营养状态进行了评价.结果表明,河网区水体中TN平均质量浓度为12.50 mg.L-1(NH4+-N占67.41%),TP为1.45 mg.L-1(SRP占80.81%).河网区水体中氮、磷的时空分布特征明显,TN和NO 3--N质量浓度随季节变化特征趋于一致,NH 4+-N稍有不同;TP和SRP质量浓度随季节变化特征基本一致.从河网区进水带至出水带,水体中氮、磷质量浓度均呈逐渐下降趋势,其中TN、NH4+-N和NO3--N平均质量浓度分别从19.30、13.22和2.19mg.L-1降至7.98、4.45和1.50 mg.L-1;TP和SRP分别从1.95和1.59 mg.L-1降至1.11和0.91 mg.L-1.富营养化评价综合指数表明,河网区水体在时空尺度上均处于"极富"营养状态.

Temporal and Spatial Variation of Nitrogen and Phosphorus and Eutrophication Assessment in Downstream River Network Areas of North Canal River Watershed

Based on the water quality survey for one year in the downstream river network areas of North Canal River Watershed, variation features of inorganic nitrogen (N) and phosphorus (P) were analyzed, and water eutrophication degree of river network areas was also assessed. The results showed that the average concentration of TN was 12.50 mg·L^-1 (NH₄⁺-N, 67.41%); TP was 1.45 mg·L^-1 (SRP, 80.81%). The temporal and spatial variations of N and P in the river network areas were obvious. Various forms of TN and NO₃^--N concentrations almost had a similar change by month; NH₄⁺-N was a little different; TP and SRP also had a similar change. The concentrations of N and P all decreased gradually from water coming region to water leaving region, TN, NH₄⁺-N and NO₃^--N decreased from 19.30, 13.22 and 2.19 mg·L^-1 to 7.98, 4.45 and 1.50 mg·L^-1 on average, respectively; TP and SRP were from 1.95 and 1.59 mg·L^-1 to 1.11 and 0.91 mg·L^-1. Water eutrophication degrees of river network areas were all the highest level at both temporal and spatial scale.