1997—2011年长江徐六泾江段流量与水质变化

Variation of Flow Rate and Water Quality of Changjiang River at Xuliujing Section in 1997- 2011

将5—9月和10至次年4月分别作为汛期和非汛期,对1997—2011年长江徐六泾江段的流量与水质变化作趋势分析,探讨徐六泾江段水质污染的变化规律及主要原因。结果表明,徐六泾江段多年平均流量为(27 927±4 699)m3·s-1,最高值出现在1998年,最低值出现在2011年。徐六泾江段汛期流量显著高于非汛期,两者的比值为1.73～2.95。非汛期的COD浓度高于汛期,且其年均值与流量呈显著负相关;14 a中COD Mn浓度呈整体下降趋势,且与流量呈显著正相关;BOD5浓度表现为非汛期高于汛期,14 a中汛期BOD5浓度呈下降趋势,但非汛期和年均值变化不明显;氨氮质量浓度范围为0.07～0.83 mg·L-1,一般表现为非汛期高于汛期,并在2002年出现最高值之后趋于平稳;总磷质量浓度范围为0.012～0.450 mg·L-1,其变化趋势同氨氮类似。氮和磷是长江徐六泾江段的主要污染因子。

Xuliujing is located on the south side of the Changjiang River and in Changshu of Jiangsu Province.The section of the river at Xuliujing is considered to be the starting point of the estuary of the Changjiang River.To explore laws and main causes of the changes in water pollution at the Xuliujing Section,analysis was done of data on flows available for trends of the variations of flow rate and water quality of the Changjiang River at the Xuliujing Section during the period from 1997 to 2011.The Changjiang River is in the flood season from May to September,and turns into the non-flood season from October to April of the following year.The average flow rate of the fourteen years was （27 927±4 699） m3 · s-1,with the highest occurring in 1998 and the lowest in 2011.The flow rate at the Xuliujing Section was significantly higher （1.73-2.95 fold） in the flood season than in the non-flood season.By contrast,annual average permanganate index （CODMn） decreased and was positively related to flow rate.The annual average biological oxygen demand （BOD5） showed a trend of decreasing from 1997 to 2011 and being higher in the non-flood season than in the flood season.In most years between 1997 and 2011,the concentration of ammonia nitrogen （NH3-N） was higher in the non-flood season than in the flood season and was the lowest in 1998 and the highest in 2002.The variation of the concentration of total phosphorus （TP） was similar to that of NH3-N during 1997-2011.The major pollution factors exceeding the standard limits were nitrogen and phosphorus.