Seasonal variations in concentration and lability of dissolved organic carbon in Tokyo Bay
Seasonal variations in concentration and lability of dissolved organic carbon in Tokyo Bay
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DOI：
10.5194/bg-12-269-2015
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发表时间：
2015-01-01
期刊：
影响因子：
4.9
通讯作者：
Kanda, J.
中科院分区：
文献类型：
--
作者：
Kubo, A.;Yamamoto-Kawai, M.;Kanda, J.
在日本东京湾的三个站点和两个流入海湾的淡水源中，研究了柠檬酸和生物可利用的溶解有机碳（DOC）的浓度及其季节变化。平均而言，柠檬酸DOC（RDOC），作为一个残余的DOC瓶培养150天后，占芝浦污水处理厂（STP）的出水，67%的总DOC的78%，在荒川河上游的水，66%，在荒川河下游的水，和78%的表面湾水。生物可利用DOC（BDOC）浓度，定义为DOC减去RDOC，低于RDOC在所有站点。在淡水环境中，RDOC浓度全年几乎保持不变。在海湾中，由于淡水输入和生物生产，RDOC在春季和夏季高于秋季和冬季。根据RDOC、盐度和叶绿素a的多元回归分析，估算出该湾浮游植物、陆地和大洋沃茨中RDOC的相对浓度分别为8- 10%、21- 32%和59- 69%。此外，与以前的数据从1972年的比较显示，RDOC和BDOC的浓度下降了33%和74%，在淡水站点和39%和76%，在东京湾，而RDOC DOC DOC的比例增加。DOC浓度和组成的变化可能是由于进入系统的STP流出物的量增加。由于BDOC的商业化，东京湾将大部分RDOC输出到公海。
Concentrations of recalcitrant and bioavailable dissolved organic carbon (DOC) and their seasonal variations were investigated at three stations in Tokyo Bay, Japan, and in two freshwater sources flowing into the bay. On average, recalcitrant DOC (RDOC), as a remnant of DOC after 150 days of bottle incubation, accounted for 78% of the total DOC in Shibaura sewage treatment plant (STP) effluent, 67% in the upper Arakawa River water, 66% in the lower Arakawa River water, and 78% in surface bay water. Bioavailable DOC (BDOC) concentrations, defined as DOC minus RDOC, were lower than RDOC at all stations. In freshwater environments, RDOC concentrations were almost constant throughout the year. In the bay, RDOC was higher during spring and summer than in autumn and winter because of freshwater input and biological production. The relative concentration of RDOC in the bay derived from phytoplankton, terrestrial, and open-oceanic waters was estimated to be 8-10, 21-32, and 59-69 %, respectively, based on multiple regression analysis of RDOC, salinity, and chl a. In addition, comparison with previous data from 1972 revealed that concentrations of RDOC and BDOC have decreased by 33 and 74% at freshwater sites and 39 and 76% in Tokyo Bay, while the ratio of RDOC to DOC has increased. The change in DOC concentration and composition was probably due to increased amounts of STP effluent entering the system. Tokyo Bay exported mostly RDOC to the open ocean because of the remineralization of BDOC.