大鹏湾海水中各形态无机氮的分布变化

Distribution of various inorganic nitrogenous species in the seawater of Dapeng Bay

依据香港特别行政区环境保护署于1999—2007年106个航次的调查资料,并结合国家海洋局南海分局于1998—2007年10个航次的调查资料,简要描述和分析大鹏湾中海水各形态无机氮含量平均分布的变化。结果表明,由于受到香港和深圳的陆源排放的影响,氨氮含量在吐露港西部和沙头角海区明显偏高。大鹏湾香港海区全层海水中可溶性无机氮(dissolved inorganic nitrogen,DIN)各组分的平均百分含量高低顺序为氨氮>硝酸盐>亚硝酸盐,而氨氮、硝酸盐和亚硝酸盐的多年平均含量分别为0.041、0.019和0.007mg.L-1。在夏季,外海高盐水入侵导致底层水中的硝酸盐含量明显高于表层水中的硝酸盐含量。调查期间氨氮含量航次均值的年际变化呈较明显下降趋势,而硝酸盐和亚硝酸盐含量航次均值的年际变化不大。

Distributions of various inorganic nitrogenous species in the seawater of the Dapeng Bay are analyzed based on the data obtained from 106 cruises by the Environmental Protection Department of the Government of Hongkong Special Admin-istrative Region from 1999 to 2007 and 10 cruises by the South China Sea Sub-administration of the State Oceanic Admini-stration from 1998 to 2007.The results show that ammonia nitrogen contents were higher in the western Tolo Harbour and the Sha Tau Kok Sea than in the other areas in the Dapeng Bay,due to the impact of continental discharges into the coastal zones from Hongkong and Shenzhen.The average percentage contents of various components of dissolved inorganic nitrogen（DIN） were in the order of ammonia nitrogen nitrate nitrite,and the multi-year average contents of ammonia nitrogen,nitrate,and nitrite were 0.041,0.019,and 0.007mg.L？1,respectively,in the whole layer of seawater in Hongkong zone of the Dapeng Bay.In summer,the content of nitrate was much higher in the bottom water than that of the surface water due to intrusion of high salinity water from the open sea.The inter-annual variation trends of the cruise-average content of ammonia nitrogen de-creased,and the nitrate and nitrite kept steady during the nine years.