长江口及毗邻海域粪大肠菌和细菌总数在夏秋季的变化

DISTRIBUTION OF THE FECAL COLIFORM AND TOTAL BACTERIA IN CHANGJIANG ESTUARY AND ITS ADJACENT SEA IN SUMMER AND AUTUMN

2005年夏、秋季对长江口及毗邻海域（长江口、杭州湾和舟山海域）进行了粪大肠菌群和细菌总数的调查研究,并分析了近10年来的变化趋势,结果表明：夏季长江口及毗邻海域表层水体分大肠菌数平均值〈20个/L,仅长江口的西部海域粪大肠菌群数量在40~80个/L之间,其余海域基本未检出;秋季表层水体粪大肠菌群数量平均为101个/L,变幅范围为〈20~24000个/L,其中横沙一带海域存在1个数量为105个/L以上的高值区;夏季长江口及毗邻海域表层水体细菌总数平均为6.4×102cfu/mL,变幅范围为2.0×102~7.3×103cfu/mL,高值区位于舟山群岛以东海域、长江口的中北部及南部等海域,细菌总数在103cfu/mL以上;秋季表层水体细菌总数平均为4.7×103cfu/mL,明显高于夏季,变幅范围为1.3×103~1.8×104cfu/mL,高值区主要出现在长江口东南部、杭州湾西部、舟山海区的中北部等海域,细菌总数在104~105cfu/mL之间;1996—2005年期间,全海域及各海区粪大肠菌群数量在1999年均达到最高,然后逐渐下降,在1996—1999年间海域的细菌数量呈明显的上升趋势,2000年以后数量逐渐减少,估计与海域的有机污染程度下降有关。

A study about distribution of the fecal coliform and total bacteria was carried out in Changjiang Estuary and its adjacent sea in summer and autumn in 2005,the results showed： in summer the average value of fecal coliform in the surface water was less than 20 ind/L,and it was under limit of detection in most sea area except the west of Changjiang Estuary（about 40-80 ind/L）;in autumn the average value of fecal coliform was 101 ind/L,and the number changed between 20 to 240000 ind/L with a high value（105 ind/L） appearing in Hengsha island area;in summer the average of total bacteria in the surface water was 6.4 102 cfu/L,and the number changed between 2.0 102 to 7.3 103 cfu/L with a high value（103 cfu/L） appearing in the middle north and the south of Changjiang Estuary and the east of Zhoushan island;in autumn the average value of total bacteria was 4.7 103 cfu/mL,much more than that in summer,and the number changed between 1.3 103 to 1.8 104 cfu/mL with a high value（104~105 cfu/mL） appearing in the southeast of Changjiang Estuary,the west of Hangzhou Bay and the middle north of Zhoushan island;from 1996 to 2005,the number of fecal coliform in the study area arrived the peak in 1999,then decreased slowly;the number of total bacteria in the study area was obviously increased from 1996 to 1999,then decreased after 2000,which could have relations with the reducing organic pollution.