钱塘江河口水质时段离散程度及对污染物通量估算的影响

Dispersion Degree of Water Quality and Its Influence on the Estimation for Pollutant Fluxs in Qiantang Estuary

为估算钱塘江河口的污染物通量,基于钱塘江河口之江站2016年COD_(Mn)、TN、TP等3个水质指标的逐日水质数据及逐日净下泄流量,分析3个水质指标的时段离散程度、与净下泄流量的相关性及污染物月通量估算时忽略时均离散通量引起的误差大小。结果表明,COD_(Mn)、TN、TP等3个水质指标的月内变异系数分别为0.06~0.16、0.04~0.21、0.12~0.26,远小于净下泄流量的变异系数0.21~0.76;COD_(Mn)、TP两个水质指标与径流量并不存在明显的同向变化趋势,而TN与径流量具有较显著的同向变化趋势;各污染物逐月通量的时均离散误差不大,若无法获取逐日流量和逐日水质数据,采用月均流量和水质资料计算污染物通量也可以得到较准确估值。

To estimate pollutant flux in Qiantang Estuary,the time interval dispersion of the three water quality indicators(COD_(Mn),TN,TP),the correlation with the net discharge,and the error caused by ignoring the time averaged discrete flux in the estimation of monthly pollutant flux were analyzed,based on the daily water quality data and daily net discharge of Zhijiang Station in 2016.The results show that the monthly variation coefficients of COD_(Mn),TN and TP are 0.06-0.16,0.04-0.21 and 0.12-0.26,respectively,which are far less than the variation coefficients of net discharge of 0.21-0.76;The water quality indicators of COD_(Mn)and TP and runoff have no obvious change trend in the same direction,while TN and runoff have a significant change trend in the same direction;The time average dispersion error of the monthly flux of each pollutant is small.If the daily flow and daily water quality data cannot be obtained,the pollutant flux can also be estimated more accurately by using the monthly average flow and water quality data.