长江口邻近海域夏季沉积物硝化细菌与硝化作用

Nitrifying Bacteria and Nitrification in Sediment at the Adjacent Sea Area of Yangtze River Estuary in Summer

2006年6月在长江口邻近海域选择了8个站位,分别采用荧光原位杂交（FISH）法和乙炔抑制法进行现场模拟培养,研究了硝化细菌数量与硝化反应速率分布规律及其环境效应.结果表明,该海域表层沉积物中的硝化细菌数量（以湿重计）在1.87×105~3.53×105个/g之间,并表现出一定的耐盐性.硝化速率范围为101.3~514.3μmol/（m2.h）,其分布有明显的自近岸向外海逐渐降低的趋势,在长江冲淡水和杭州湾口附近海域形成2个高值域.在高盐度海区硝化细菌数量对硝化速率的影响率高达87.7%,是影响硝化反应速率的主要因素.硝化作用每天在该海域转化的无机氮通量为4.68×105kg,消耗的DO通量为6.07×104mol,表明硝化作用是影响长江口邻近海域夏初DIN形态分布和底层DO分布的主要因素之一.

The influence factors and environmental effects of nitrification process were discussed based on the measurements of nitrifier quantities and nitrification rates at eight sites off Yangtze River Estuary in June 2006. Using FISH （Fluorescence in situ hybridization） method, the nitrifying bacteria were counted as 1.87 ×10^5 -3.53 ×10^5 eells/g wet weight and exhibited salt tolerance to some extent. The nitrification rates, measured by acetylene inhibition technique, ranged from 101.3 to 514.3 μmol/（m2·h） and had a decreased gradient from nearshore to offshore sediment with two high value regions located at the mouth of Yangtze River and Hangzhou Bay respectively. The nitrifier quantity was a main factor to effect nitrification rates at high-salinity sea area, with an influence ratio of 87.7%. Fluxes of transformed nitrogen and consumed oxygen by nitrification process were 4.68×10^5 kg and 6.07×10^4 mol per day respectively, suggesting that nitrification would be an important factor for the distribution of DIN species and DO at bottom water in early summer.