滇池水体BOD5和CODMn空间变化研究

通过对滇池进行全湖集中采样和分析,揭示了滇池水体五日生化需氧量(BOD5)和高锰酸盐指数(CODMn)的空间变化规律.BOD5和CODMn变化范围分别是2.3～7.9mg/L,5.1～15.4mg/L,BOD5平均值草海(5.9mg/L)高于外海(5.1mg/L)CODMn平均值外海(10.17mg/L)高于草海(8.67mg/L),2个指标在入河口水域都相对较高.水平方向上,BOD5变化特点是南北高,中间低,西部高,东部低.垂直方向向上BOD5随水深增加递减.而CODMn的高值区域主要出现在草海和外海海埂、盘龙江、大青河入湖口水域、西部观音水域以及东北部宝象河、东部梁王河和捞鱼河入湖口水域、东南柴河入湖口水域.垂直方向上,从表层到水-沉积物界面水体,其CODMn都呈增加趋势.随着工业点源污染的控制,城市生活污水的排入和面源有机污染物的输入以及内源释放是决定滇池BOD5和CODMn空间变化的主要原因.

Studies on the spatial variation of BOD5 and CODMn in Dianchi Lake waters

Through the centralized sampling and analysis all over Dianchi Lake, the spatial variation rule of five days biochemical oxygendemand (BOD5 ) and permenganate index of oxygen demand (CODMn) in Dianchi Lake waters were revealed. The variation of BOD5 and CODMn ranged from 2.3~7.9mg/L and 5.1~15.4mg/L respectively. The mean value of BOD5 in Caohai (5.9mg/L) was higher than that in Waihai (5.1mg/L), the mean value of CODMn in Waihai (10.17mg/L) was higher than that in Caohai (8.67mg/L). These two indices in the waters entering estuaries were higher relatively. In horizontal direction, BOD5 of the north and the south was higher than that of middle water area, the west was higher than the variation character of BOD5 was high in the north and the south, with low in the middle and high in the west and low in the east; and decreased successively with the increase of water depth in vertical direction. The high value area of CODMn occurred mainly in Caohai and Haigeng of Waihai and the river estuary of Panlongjiang. Daqing river estuarywater, west Guanyinshan waters, and north east Baoxiang river, east Liangwang river, Laoyu river, Chaihe river estuary waters. CODMn of Dianchi Lake tended to increased in vertical direction in the waters from surface to the interface of water and deposition. The main reason deciding the spatial variation of BOD5 and CODMn in Dianchi Lake was the input of urban living sewage, surface source organic pollutants and internal release along with the control of industrial point source pollution.