香港牛尾海中颗粒有机物的自养生产和异养降解

Autotrophic Production and Heterotrophic Removal of POM in Port Shelter,Hong Kong,China

文章依据2000-2014年的月度监测资料,分析了南海北部牛尾海中颗粒有机物(POM)质量浓度的时空分布。应用回归分析,并结合叶绿素a实测数据探讨湾中POM滞留时间(TPOM)。应用二元混合质量平衡模式,并结合盐度实测数据探讨湾中自养生产和异养降解过程产生的POM不平衡量(ΔPOM)。结果显示湾中POM质量浓度为(0.84±0.49)mg/L,底层高于表层,湾顶水域高于湾的主区;季节变化和年变化不大,湿季(4-9月)略高于干季(10月-翌年3月)。TPOM约为7 d,暗示湾中POM快速循环。ΔPOM约为0.2 mg/L,表明水交换把POM从湾中带入外海。牛尾海中异养降解POM总量约是自养生产POM总量的91%,表明湾中POM自养生产占优势。由此得出结论,牛尾海具有高自养生产能力,同时也具有相当的异养降解能力,是大气CO2的汇。

Monthly data between 2000 and 2014 were used to analyze the temporal and spatial distributions of POM in Port Shelter,northern South China Sea.The POM residence time(TPOM)were also investigated using a regression analysis in combination with chlorophyll-a(Chl-a)measurements while excess POM(ΔPOM),produced by the biogeochemical processes of autotrophic production and heterotrophic removal,was determined using a two-component mixing mass-balance model in combination with salinity measurements.The results showed that the POM concentration was(0.84±0.49)mg/L higher in the bottom-water compared with the surface-water and higher in the waters adjacent to the bay-roof compared with the bay’s main zone.Seasonal changes and annual variability in the POM were small,the POM concentration in the wet season(Apr–Sep)was slightly higher than dry season(Oct–Mar).TDOPwas about 7 d.This implied that the POM cycle in the bay was rapid.TheΔPOM was about 0.2 mg/L in the bay,suggesting that the water exchange removed POM from the bay to the open sea.The total heterotrophic removal of POM was found to be about 91%of the total autotrophic production of POM,suggesting that the autotrophic production of POM is dominant in the bay.In conclusion,Port Shelter is very productive and,at the same time,fairly heterotrophic.It is a sink of atmospheric CO2.