滇池沉积物内源氮释放风险及控制分区

采用淹水培养法测定了滇池20cm沉积物可释放态氮(EN)、潜在可释放态氮(MN)及稳定态氮(FN)含量,并分析了其空间分布特征,结合沉积物定年数据计算了不同形态氮蓄积量.依据沉积物-水界面氮释放通量、EN蓄积量及MN蓄积量对滇池沉积物内源氮污染状况进行分区,评估了不同区域滇池沉积物内源氮释放风险,并对不同分区提出了污染控制措施.结果表明,滇池沉积物内源氮释放风险:外海南部外海北部外海中部草海,潜在释放风险:外海南部外海中部草海外海北部;滇池沉积物氮污染有由北向南转移趋势;滇池全湖20cm沉积物蓄积TN5757.90t,EN637.72t,MN1320.76t,FN3799.42t.根据沉积物氮污染滇池可划分为高污染区、中度污染区、低污染区及安全区,分别占全湖面积的13.51%、15.02%、46.06%、25.42%,其中高污染区主要分布在草海、外海北部盘龙江附近;中度污染区主要分布在高污染区以下从宝象河到观音山区域及滇池出水口海口等区域;低污染区主要分布在中度污染区以下从广谱大沟到整个外海南部区域.高污染区可采取底泥环保疏浚技术,中度污染区可采取安全生态性高的原位控制技术,低污染区可采取覆盖技术,配合水生植被修复技术.

The risk and control division of endogenous nitrogen release in Dianchi Lake sediment

The waterlogged incubation method was used to test the content of the released nitrogen (EN), the potential released nitrogen (MN) and the steady nitrogen (FN) of the Dianchi Lake 20cm sediment, and the analysis of its spatial distribution, combined with the sediment dating data to calculate the amount of the different burial nitrogen forms. The nitrogen pollution of the sediment in Dianchi Lake was zoned based on the sediment-water interface nitrogen fluxes, and the amount of the burial EN and MN. The nitrogen release risk of the different regions of Dianchi Lake sediments was also evaluated, and their pollution control measures for different zones were also proposed. The results show,the risk order of nitrogen release of the different zones of Dianchi Lake sediments was South of Waihai >northern of Waihai >central of Waihai >Caohai, and the potential risk order was South of Waihai >central of Waihai >Caohai >northern of Waihai; there is a tendency of the nitrogen pollution of the Dianchi Lake sediment to transfer from north to south; the amounts of the 20cm sediment accumulation were TN 5757.90t, EN 637.72t, MN 1320.76t and FN 3799.42t for the whole lake. The nitrogen pollution of Dianchi sediment can be divided into four levels of high pollution area; medium pollution area, low pollution area and safety zone, which were 13.51%, 15.02%, 46.06%, and 25.42% of the whole lake, respectively. High pollution areas were mainly distributed in Caohai and Northern near Panlong river; medium pollution area were mainly distributed in high pollution below from Baoxiang river to Guanyin mountain region and a small area of Dianchi Lake outlet Haikou; low pollution area were mainly distributed in medium pollution below from Guangpudagou river to all of the southern of Waihai region. The sediment in high pollution area should be taken the environmental dredged and restoration technology; the medium pollution area should be take the safety and the high-level in situ control technology; for the low pollution area, the natural cover and aquatic plant restoration technology should be used.