大鹏湾中溶解态总氮和总磷的多年调查结果分析

摘要

依据2000-2010年每月1次的调查资料,简要描述和讨论大鹏湾海水中溶解态总氮(DTN)和溶解态总磷(DTP)质量浓度的空间分布和时间变化.结果表明由于受到香港和深圳陆源排放的影响,DTN和DTP质量浓度在吐露港和沙头角附近水域1年4季都较高.DTN和DTP的平均质量浓度分别为0.21和0.03 mg.L-1,比溶解态无机氮(DIN)和溶解态无机磷( DIP)的高1倍以上,表明大鹏湾海水中溶解态有机氮(DON)和溶解态有机磷(DOP)分别是DTN和DTP的主要赋存形态.平均DTN/DTP原子比＞16,反映了大鹏湾海水中磷可能是海洋浮游生物生长繁殖的限制因素.夏季,由于南海北部陆架低温、高盐和高营养盐底层水潜入湾内,底层DTN和DTP质量浓度明显高于其他季节.11年调查期间,DTN质量浓度的年际变化趋势平稳,DTP质量浓度的年际变化呈较明显的下降趋势,而DTN/DTP原子比的年际变化呈较明显的上升趋势.%Based on the data obtained from monthly cruises from 2000 to 2010, the spatial distributions and temporal variations of dissolved total nitrogen (DTN) and dissolved total phosphorus (DTP) concentrations in the seawater of Mirs Bay were briefly presented and discussed. It was shown that die DTN and DTP concentrations were perennially higher in the Tolo Harbour zone and the Sha Tau Kok adjacent zone than the other zones of the bay due to the impact of the seaward discharges from Hongkong and Shen Zhen. The average concentrations of DTN and DTP were 0.21 and 0.03 mg-L-1, higher than twice the dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) respectively, showing that the dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) were the main existing forms of DTN and DTP. The average DTN/DTP atomic ratio was >16, suggesting that the growth and breeding of marine planktons were probably limited by the phosphorus. In the bottom, the concentrations of DTN and DTP were much higher in summer than the other seasons due to the intrusion of low temperature, high salinity and high nutrient bottom-water from the northern South China Sea coastal continental shelf. During the 11 years in investigation, the inter-annual variation of the DTN concentration was with a reposeful trend, the DTP concentration undergone a trend of decrease, and the DTN/DTP atomic ratio witnessed an increasing trend.