九龙江口红树林湿地沉积物中有机碳和氮的分布特征及来源辨析

Distributions and Sources of Organic Carbon and Nitrogen in Mangrove Sediments in the Jiulong River Estuary

【目的】探讨九龙江口红树林湿地沉积物中总有机碳(TOC)和总氮(TN)的影响因素及来源,加深对红树林湿地中碳和氮的生物地球化学过程的认识。【方法】测定九龙江口红树林湿地表层沉积物粒度、TOC和TN含量,并对其分布特征进行分析。利用TOC/TN比值分析有机质来源及不同来源的贡献率。【结果】九龙江口红树林湿地沉积物中TOC和TN的含量分别为1.24%~3.81%和1.19~2.05mg/g,TOC/TN比值为11.6~26.3,TOC、TN含量和TOC/TN的平面分布均呈现出由陆向海方向逐渐降低的趋势。沉积物中TOC和TN含量没有表现出明显的粒度效应。【结论】控制沉积物中TOC和TN含量分布的主要因素并不是粒度效应,而可能是其来源。沉积物中TOC和TN的主要来源可能是红树林植物碎屑、养殖废水输入的有机碳和氮污染,以及海洋浮游植物碎屑。

【Objective】In order to investigate the influencing factors and sources of total organic carbon(TOC)and total nitrogen(TN)in mangrove wetland sediments,TOC and TN in mangrove sediments in the Jiulong River estuary were analyzed.This would increase the understanding about the biogeochemical processes of carbon and nitrogen in mangrove wetlands.【Methods】The sediment grain size,TOC and TN contents in surface sediments in the mangrove wetland in the Jiulong River estuary were analyzed,and their spatial distribution characteristics were investigated.TOC/TN ratios were used to analyze the sources of sedi-ment organic matter and the contributions of different sources.【Results】Total organic carbon and TN concentrations and TOC/TN ratios in mangrove sediments ranged from 1.24%-3.81%,1.19-2.05 mg/g and 11.6-26.3,respectively.As for the spatial distributions of TOC and TN concentrations and C/N ratios,they were all decreased gradually from land to-ward sea.【Conclusion】The major influencing factor of TOC and TN in mangrove sediments is not the grain size effect,but likely is the material source.The sources of TOC and TN in sediments likely are the mangrove detritus,organic carbon and nitrogen pollution from the aquaculture waste water and marine phytoplankton detritus.