粤东五华河悬浮颗粒有机质的组成及输出通量

Composition and Transported Fluxes of Riverine Particulate Organic Matter of the Wuhua River,East Guangdong Province,China

河流碳输出过程构成全球碳循环的一个重要环节。基于一个完整水文年的月周期性采样分析,讨论了五华河径流中悬浮颗粒有机质(POM)的性质及其来源,估算了流域有机质的输出通量。结果表明:五华河径流中颗粒有机碳(POC)和颗粒有机氮(PON)的平均含量分别为0.77 mg/L和0.12 mg/L,其中汛期含量高于枯水期;五华河河流总悬浮颗粒物(TSS)、POC、PON含量以及河流颗粒有机质C/N比与流量的关系揭示五华河径流中POM主要源自流域土壤有机质的侵蚀,而且在迁移过程中受到水体微生物的分解;五华河流域POC和PON年输出通量分别为430 kg/(km2·a)和70 kg/(km2·a),其中汛期POC和PON输出量分别占全年输出总量的74.23%和76.17%。

Abstract： Carbon transportation by river system constitutes a key link of the global carbon cycle. Based on monthly sampling and analysis of riverine particulate organic matter for a full hydrological year in the Wuhua River, eastern Guangdong Province, the characteristics and sources of particulate organic matter in the river were discussed and carbon transport fluxes were estimated. The results show that the average contents of particulate organic carbon （POC） and particulate organic nitrogen （PON） in the Wuhua Riv- er are 0. 77 mg/L and 0. 12 mg/L, respectively, which are much higher during the flood season than those during the dry season. The relationships between discharge and the TSS, POC, PON contents, and the ratio of C to N reveal that the POM of the Wuhua River is mainly from soil organic matter within the drainage basin, which is decomposed by microorganisms during transportation. POC and PON fluxes ex- ported by the Wuhua River are 430 kg/（ km2. a） and 70 kg/（ km2. a）, respectively. The output fluxes in the flood season account for 74. 23% and 76. 17% of the total annual output. Key words： riverine particulate organic matter; C/N ratio; soil erosion; the Wuhua River