珠江中下游颗粒有机质的碳氮℃稳定同位素、氨基酸和木质素组成及其地球化学意义

从东江到珠江口采集了悬浮颗粒物,通过测定总有机质的元素（TOC、TN）、同位素（δ13C、δ15N）组成以及生物标志物（氨基酸、木质素）等地球化学性质,来揭示颗粒有机质的来源和组成。结果表明,浮游生物（13%-52%）和土壤（45%-77%）是珠江颗粒有机质的主要来源,植物（0%-11%）对颗粒物的贡献较小。颗粒有机质含有高比例的氨基酸碳（TAAC）,说明浮游生物对颗粒物的重要性。氨基酸的降解指数（DI）在-0.51到0.79之间,说明这些水生来源有机质的降解程度比较小。木质素的降解参数（Ad/Al、3,5-BD/V）较大,表明珠江颗粒有机碳的陆源来源主要是土壤。在颗粒物中检测到了少量的二氨基庚二酸（Dapa）,说明细菌对颗粒有机碳也有所贡献。不同环境中颗粒物的木质素组成主要与颗粒物丰度和粒径有关：（1）相对于河流,水库颗粒物中的木质素含量显著偏低,降解程度更高；（2）相对于中游,下游颗粒物丰度较高,木质素含量较高。

Stable carbon and nitrogen isotopic,amino acids and lignin compositions and geochemical significance of particulate organic matter from the middle and lower reaches of the Pearl River

Suspended particulate matters （SPM） were extensively collected from the Dongjiang River to the Pearl River Estuary. The elemental （TOC, TN） and isotopic （δ13C, δ15N） compositions, as well as biomarkers （amino acids, lignin phenols）, were determined to elucidate the sources and compositions of particulate organic matter （POM）. The results indicate that POM in the Pearl River is primarily derived from plankton （13%-52%） and soil （45%-77%）, less contribution of plants （0%-11%）. High proportion of amino acid carbon （TAAC） in POM shows the importance of plankton input to POM. Degradation indices （DI） of amino acids range from -0.51 to 0.79, suggesting that the aquatic organism-derived organic matter in SPM has a relatively lower degradation level. The diagenetic parameters （Ad/Al and 3,5-BD/V） of lignin are relatively high, which indicate that the terrestrial organic matter in SPM is mainly originated from soil. In addition, the detection of low contents of diaminopimelic acid （Dapa） in SPM also indicate a contribution of bacteria. The lignin compositions are associated with the abundance and size of SPM： for example, （1） the reservoir SPM contains low content of lignin and significantly＆amp;nbsp;altered terrestrial organic matter relative to the riverine SPM; （2） the SPM are high in abundance and have high lignin content in the lower reach of the Pearl River relative to the middle reach.