洱海沉积物有机质及其组分空间分布特征

对有机质不同组分〔TOM(总有机质)、ASOM(土壤活性有机质)、LFOM(轻组有机质)和HFOM(重组有机质)〕在洱海沉积物表层和垂向的空间分布、来源特征进行了调查研究. 结果表明:洱海表层沉积物中w(TOM)在25.7～148.9g/kg之间,w(ASOM)在4.4～62.5g/kg之间,w(LFOM)在0.2～4.2g/kg之间；w(TOM)和w(ASOM)空间分布趋势为北部湖区＞南部湖区＞中部湖区,西部湖区高于东部湖区；w(LFOM)分布趋势为南部湖区＞中部湖区＞北部湖区；洱海沉积物各组分有机质均为表层富集,而在8~30cm基本稳定,有机质组分活性越强,其富集速率越大. 湖心平台沉积物中TOM富集速率最大,北部湖湾沉积物中ASOM富集速率最大,中部湖区LFOM富集速率最大. 与长江中下游湖泊相比,洱海沉积物中有机质含量高、活性强、矿化程度低；与滇池相比,其表层富集速率较低. 北部三江和西部十八溪是洱海有机质的主要外源,退化的沉水植被是其主要内源. 水生植物残体沉积和人类活动等是影响洱海沉积物有机质空间分布及其活性的主要因素. 

Characteristics of Composition and Spatial Distribution of Organic Matter in the Sediment of Erhai Lake

This study aims to provide the information for the control of endogenous pollution in the sediment of Erhai Lake with investigation on characteristics of composition and spatial distribution of the organic matter. The results showed that the content of the total organic matter (TOM) in the surface layer of the sediment in Erhai Lake was in 25.7-148.9g/kg, that of the active soil organic matter (ASOM) was in 4.4-62.5g/kg, and that of the light fraction organic matter (LFOM) in 0.2-4.2g/kg. This indicated that the organic matter in the sediment of Erhai Lake had relatively high contents, strong activity and low degree of mineralization. The spatial distribution trend of TOM and ASOM in the north section is higher than that in the south and the central sections, and this trend is higher in the west than that in the east as well. The spatial distribution trend of LFOM for the south is higher than that in the central and the north sections. Components of organic matters in the sediment of Erhai Lake showed a significant enrichment in the surface layer and the enrichment was for 8cm deep. The stronger the activity of the organic matter the greater its enrichment. The enrichment rate of LFOM was the highest in the sediment at the central platform. Organic matters in the sediment of Erhai Lake were with higher content, stronger activity and lower mineralization, compared with in lakes from the middle and the lower reaches of the Yangtze River region. The enrichment rate of organic matters in the surface layer of Erhai Lake was lower than that in Dianchi Lake. The main external source of the organic matter in Erhai Lake was the three rivers on its north and the western eighteen creeks on its west, while the primary internal source was the submerged aquatic vegetation degradation. Growth and degradation of aquatic plants and human activities were the main factors affecting the spatial distribution of organic matters and their activities in the sediment of Erhai Lake.