洱海环境沉积学研究——表层沉积物营养盐与粒度分布

The Environment Sedimentological Study of Erhai Lake—Correlation between nutrients and particle size distribution in superficial sediments

云南洱海表层沉积物营养盐与粒度分布的相互关系的研究结果表明 :湖泊水动力较弱的水域 ,TP、Fe_P、O_P与粘土矿物的相关性较好。而近岸水动力较大的水域 ,如河溪入湖处 ,有利于TN、TOC、氨氮、残留磷的富集 ,它们与碎屑矿物的相关性很好 ,如石英和方解石。另外 ,沉积物中粘土矿物越多 ,粒径越小 ,沉积物对磷的吸附作用就越强 ,在洱海这种类型的沉积物主要分布在远岸深水 -较深水的北部湖心。

Erhai lake,the second largest lake in the Yunnan Plateau in Southwest China,is located in Dali Prefecture with 25°35′to 25°58′Nin Latitude 100°05′to 100°07′Ein logitude Erhai Lake is a typical rift lake in the Dali Basin developed along the YuaJiang Hoonghe great fault and has been in existence since Later Pliocene.In November 1996(winter),the lake water quality was still in a poor condition,with a low concentration of dissolved oxygen.The lowest Do value was 1.7 mg/L.Results of comprehensive assesment indicate that water quality at most of the sections was grade III,with some of them reaching grade IV.The sudden deterioration of water quality in Lake Erhai has clearly indicated that the lake′s water quality is at a critical state.In order to prevent occurrence of more eutrophication in the future,study of nutrient and pollutant emissions from sediment to the lake by environment sedimentology methods would be necessary.By Studying relationship between nutrient and particle size distribution for the Erhai lake′s superficial seddiments,the results show that clay mineral is generally positively correlated with total phosphorus,Fe P and O P. The multiple regression results suggest that there are apparently positive correlation among TN,TON(total organic nitrogen),T HN 3,A′% and deris minerals.The TP content is mainly comprised of inorganic posphorus and positively correlated with sediments with higher content of clay minerals and smaller particle size mainly deposited in the lake center in the northern part of Erhai lake.