珠江口表层沉积物有机碳不同浸提组分的空间分布特征

活性有机碳是海洋沉积物有机碳的重要组成部分，研究河口区沉积物不同浸提组分的活性有机碳对于认知近海活性有机碳的迁移转化过程具有重要意义，可为全球碳循环研究提供基础。本文于2013年7月采集珠江口表层沉积物样品，通过盐提取（SEC）、水提取（WEC）、氯仿熏蒸提取（MBC）和酸提取（AHC）等方法测定其活性有机碳，研究其分布规律及相互关系。结果表明:（1）珠江口表层沉积物SEC、WEC、MBC和AHC的平均含量分别为（768.0±23.5）×10-6、（688.1±31.2）×10-6、（963.2±26.4）×10-6和（3040.7±18.2）×10-6；（2）沉积物SEC和AHC含量由西北部向东南部逐渐减少，而MBC含量由口外向西北口内逐渐减少，WEC空间分布则相对均匀；（3）陆源输入的较难降解的活性有机碳主要在西部区域沉积，而微生物活性有机碳量则主要在东南部口外处沉积。总体来看，受人类活动的影响，珠江口沉积物中的活性有机碳含量相对较高，不利于其有机碳的埋藏。

Distribution of labile organic carbon using different extract method in the surface sediments of Pearl River Estuary

Labile organic carbon(LOC)is a chief component in marine sediment organic carbon.It is important to study different types of sediment LOC in estuaries for better understanding of its offshore migration and transformation process.The sediment LOC could provide a basis information for the research of global carbon cycle.In this study, we investigated the distribution patterns of the salt extractable carbon (SEC), water extractable carbon (WEC), chloroform fumigation extractable carbon (MBC) and acid hydrolysable carbon (AHC)in the surface sediment in Pearl River Estuary (PRE).The result showed the average content of SEC, WEC, MBC and AHC were 768.0×10-6, 688.1×10-6, 963.2×10-6 and 3040.7×10-6 in the PRE, respectively.The content of SEC and AHC decreased gradually from the northwest to the southeast, while the MBC content decreased gradually from the outside of PRE to the northwest region.The distribution of WEC was relatively homogenous.It suggested that the recalcitrant fraction of LOC from land input was mainly deposited in the western region, while MBC was mainly deposited in the southeastern outlets.In PRE, the high anthropogenic LOC content in the sediment would have the negative impact for the burial of organic carbon.