太湖流域上游河网污染物降解系数研究

污染物在河流中物理、化学和生物过程的共同作用下浓度会发生衰减,衰减的速率可用表观降解系数表示,其中,仅有生物过程引起污染物浓度衰减的速率用生物降解系数表示.为了探究太湖流域上游河网污染物的降解规律,在20个采样点开展原位实验测算了高锰酸盐指数、氨氮(NH+4-N)、总氮(TN)和总磷(TP)的表观降解系数和生物降解系数,并分析了生物降解系数占表观降解系数的比重.结果表明,太湖流域上游河网高锰酸盐指数、NH+4-N、TN和TP的表观降解系数分别为0.0216~0.1974、0.0152~0.3123、0.0080~0.7870和0.0274~0.5914 d~(-1);生物降解系数分别为0.0083~0.1264、0.0021~0.2138、0.0021~0.0905和0.0110~0.1528 d~(-1).高锰酸盐指数、NH+4-N、TN和TP生物降解系数与表观降解系数的比值分别为19.35%~91.30%、13.85%~99.12%、13.70%~97.78%和3.94%~98.39%.太湖流域上游河网不同河段的表观降解系数和生物降解系数存在较大差异.生物降解在TN和NH+4-N表观降解中发挥的作用较大,在高锰酸盐指数和TP表观降解中发挥的作用相对较小.

A study on degradation coefficients of pollutants in the upstream river network of the Lake Taihu basin

Pollutant concentration becomes attenuate under the combing effects of physical, chemical and biological processes in rivers. The degradation rate can be quantified using an apparent degration coefficient. The degradation rate induced by biological process is called biodegradation coefficient. In order to explore pollutant degradation in the upstream river network of the Lake Taihu basin, on-site experiments were conducted in 20 sites. We determined apparent degradation coefficients and biodegradation coefficients of the permanganate index, ammonia (NH₄⁺-N), total nitrogen (TN) and total phosphorus (TP). The proportion of biodegradation coefficients to apparent degradation coefficients was estimated. The results showed that the apparent degradation coefficients of the permanganate index, NH₄⁺-N, TN and TP were 0.0216~0.1974 d^-1, 0.0152~0.3123 d^-1, 0.0080~0.7870 d^-1 and 0.0274~0.5914 d^-1, respectively.The biodegradation coefficients of the permanganate index, NH₄⁺-N, TN and TP were 0.0083~0.1264 d^-1, 0.0021~0.2138 d^-1, 0.0021~0.0905 d^-1 and 0.0110~0.1528 d^-1, respectively.The proportions of biodegradation coefficients to apparent degradation coefficients for the permanganate index, NH₄⁺-N, TN and TP were 19.35%~91.30%, 13.85%~99.12%, 13.70%~97.78% and 3.94%~98.39%, respectively. Our finding implies that the apparent degradation and biodegradation coefficients varied among different reaches. Biodegradation accounted for a higher proportion in the apparent degradation of TN and NH₄⁺-N than that of the permanganate index and TP.