珠江口水体有机碳的季节性变化

doi:10.11978/2015109

摘要/Abstract

摘要： 调查了珠江口不同季节颗粒有机碳(particulate organic carbon, POC)和溶解有机碳(dissolved organic carbon, DOC)含量的分布特征, 结合碳氮比值(C/N)、叶绿素a(Chl a)含量、溶解氧(dissolved oxygen, DO)含量等水化学参数, 探讨了珠江口POC、DOC来源、输送方式及混合行为的季节变化。结果表明, 珠江口水体POC可能主要受到水体自生浮游植物有机碳输入的影响, DOC可能主要来自于河流输送的陆源有机碳。在降雨量较大的5月份, POC来自自生浮游植物有机碳的贡献相对减小。降雨量同样较大的8月份DOC来自河流输送的陆源有机碳的贡献增加。不同季节珠江口水体总有机碳中的DOC一直高于POC。珠江口POC、DOC含量受到淡水与海水混合进程的影响, 淡水与海水的混合效应可能是从出虎门进入伶仃洋的低盐度区(盐度1‰~5‰的水体)开始延伸至外海。微生物的降解作用可能对POC和DOC在出虎门之前的下降趋势产生了重要影响, 而微生物对新鲜的浮游植物有机碳的利用、以及浮游植物生产量的降低和颗粒物絮凝沉降作用则可能是POC在出虎门后下降幅度大于DOC的重要原因。

关键词: 颗粒有机碳, 溶解有机碳, 有机碳含量, 不同季节, 珠江口

Abstract: Seasonal distributions of particulate organic carbon (POC) and dissolved organic carbon (DOC) concentrations, as well as their sources, transports and mixing behaviors, in the Pearl River estuary (PRE) are reported in this paper. Samples were collected in November 2013, and in February, May and August 2014. The results suggest that the sources of POC were mainly in situ aquatic phytoplankton, and the source of DOC was mainly input from terrigenous organic carbon. However, aquatic phytoplankton might have contributed less to POC in May than in other months due to intensified erosion by high rainfall during May, and terrigenous organic carbon contribution to DOC increased in August. DOC was always the main portion, i.e., higher than POC, in the total organic carbon. The conservative mixing process of riverine and marine organic carbon occurred from the low salinity zone (salinity of 1‰~5‰) near the Humen Outlet to the open sea area out of the PRE. Biological degradation may have played an important role in reducing POC and DOC concentrations in the upper reach of the Humen Outlet. Preferential consumption of fresh phytoplankton organic carbon, reduction of phytoplankton production, and flocculation and sinking of particulate matter might have collectively resulted in the much more reduction of POC than DOC in the upper reach.

Key words: Particulate organic carbon, dissolved organic carbon, mixing behavior, seasonal, Pear River estuary

中图分类号:

P734.4⁺3

郭威, 叶丰, 连忠廉, 贾国东. 珠江口水体有机碳的季节性变化[J]. 热带海洋学报, 2016, 35(4): 40-50.

GUO Wei, YE Feng, LIAN Zhonglian, JIA Guodong. Seasonal changes of organic carbon in the Pearl River estuary[J]. Journal of Tropical Oceanography, 2016, 35(4): 40-50.

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