Nitrogen,phosphorous and organic matter spatial distribution characteristics and their pollution status evaluation of sediments nutrients in lakeside zones of Taihu Lake

Top layer(0~10 cm) samples in the lakeside zones of Taihu Lake were collected.The content of organic matter(OM),total nitrogen(TN),and total phosphorus(TP) were measured,and finally pollution assessment for top layer sediments was made.The results showed that the OM levels in top layer sediments in lakeside zones of Taihu Lake ranged from1.42% to 9.96%.The spatial change trend of OM content of the top layer sediment in the decrease order as follows: Eastern Taihu Lake,Zhushan Bay,Gonghu Bay,Meiliang Bay,South shore,East shore,and West shore.TN content of the top layer sediment had a similar spatial distribution regularity with OM,ranged from 458mg/kg to 5211mg/kg.The spatial change trend of TN in the decrease order as follows: Eastern Taihu Lake,Zhushan Bay,East shore,Gonghu Bay,South shore,Meiliang Bay and West shore.TP content of the top layer sediment ranged from 128.56mg/kg to 1392.16 mg/kg.The spatial change trend of TP in the decrease order as follows: Zhushan Bay,Meiliang Bay,Eastern Taihu Lake,South shore,Gonghu Bay,East shore and West shore.OM content and TN content had very significant positive correlation(r=0.903,P0.01),but no obvious correlation with TP content(r=0.073,P0.332) in the top layer sediments.Based on comprehensive pollution index and organic index,the environmental qualities of sediments in the whole lakeside zones still belonged to clean category.Except for Eastern Taihu Lake and Zhushan Bay seriously polluted by N,P and the other areas were mild-to-moderate pollution.The organic pollution of most areas was under lower pollution level except East shore.