溶解无机氮在胶州湾沉积物-海水界面上的交换速率和通量研究

Benthic exchange rates and fluxes of dissolved inorganic ni-trogen at the sediment-water interface in Jiaozhou Bay

应用实验室培养法测定了溶解无机氮(DIN)在胶州湾16个站位沉积物-海水界面上的交换速率.结果表明,NH+4-N,NO-2-N和NO-3-N的交换速率一般分别在-0.5～1.6,0.005～0.67,-2.0～2.8 mmol/(m2@d)范围内.由于间隙水中DIN主要以NH+4-N形态存在,DIN在胶州湾沉积物-海水界面上的交换以NH+4-N的扩散为主,在大部分站位表现为由沉积物向水体的释放,NO-3-N主要来自NH+4-N的硝化反应,而NO-2-N是NH+4-N和NO-3-N之间化学转化过程的中间产物.考虑胶州湾沉积物类型,DIN在胶州湾沉积物-海水界面上的交换通量为9.68×108mmol/d,是河流输入DIN的50%左右,可提供维持胶州湾初级生产力所需DIN的52%.

Intact sediment cores were sampled at 16 sites in Jiaozhou Bay during July 2001. Through laboratory incubation experiments, benthic exchange rates of dissolved inorganic nitrogen(DIN)at the sediment-water interface were measured. Exchange rates ranged from -0.5 to 1.6 mmol/(m2·d) for NH4 -N, from -0.05 to 0.67 mmol/(m2·d) for + NO2 -N and from –2 to 2.8 mmol/(m2·d) for NO3 -N, respectively. NH4 -N diffusion between pore water and overlying water - - + was thought to be the dominant process of DIN exchange as NH4 -N was the main form of DIN in pore water. Furthermore, + effluxes from sediment to water were observed at most stations. NO3 -N was thought to come from the nitrification of NH4 - - + N while NO2 -N was produced during their transformation process. Considering the different pattern of sediments in Jiaozhou - Bay, the exchange flux of DIN between sediments and seawater was estimated as 9.68×108 mmol/d, about 50% of river input DIN. The exchange flux of DIN from sediment can provide 52% of nitrogen required by phytoplankton in Jiaozhou Bay.