三峡水库入库支流水体中营养盐季节变化及输出

Seasonal Variation and Output of Nutrient in Tributaries of Three Gorges Reservoir

三峡水库成库后,对三峡水库13条主要支流入库断面有机物、营养盐、生物量含量季节变化进行了初步研究.结果表明,支流高锰酸盐指数、化学需氧量(COD)、总氮(TN)、氨氮(NH4+-N)、总磷(TP)、叶绿素a(Chl-a)含量季节间差异较大.高锰酸盐指数范围为0.20～5.91 mg.L-1,COD含量范围4.06～30.2 mg.L-1,TN含量范围为0.542～7.44 mg.L-1,NH4+-N含量范围0.034～2.83 mg.L-1,TP含量范围为0.010～0.449 mg.L-1,Chl-a值范围为1.02～128 mg.m-3.支流受到不同程度污染,水体中N含量丰富,部分支流富营养化的限制因子为P.除苎溪河外,其余支流Chl-a含量较低,仅为贫-中营养水平.双因子方差分析表明,营养因子在时间、空间分布上均有不同程度差异.利用相关分析方法,分析了叶绿素a与营养盐之间的关系,叶绿素a与有机物、营养盐都呈显著正相关关系.支流营养盐、有机物输出负荷主要受流量控制,表现为丰水期>平水期>枯水期.13条支流不同季节排放COD、高锰酸盐指数、NH4+-N、TN和TP范围分别为1 772～6 701、380～1 875、40.1～172、249～922和9.97～50.5 g.s-1.三峡水库支流有机物、营养盐的排放应引起关注.

Mter the Three Gorges Reservoir was storage water in June 2003, organic contamination, nutrient and biomass were determined in 13 tributaries of Three Gorges Area in three seasons. Potassium permanganate index, chemical oxygen demand （COD）, ammonia nitrogen （NH4^＋ -N）, total nitrogen （TN）, total phosphorus （TP） and chlorophyll a （Chl-a） value are 0.20-5.91 mg·L^-1, 4.06-30.2 mg·L^-1, 0.542-7.44 mg·L^-1, 0.034-2.83 mg·L^-1, 0.010-0.449 mg·L^-1 and 1.02-128 mg·m^-3 respectively. The water body of tributaries is polluted at various levels. The concentration of TN is abundant. The rate of TN and TP showed that a part of tributaries eutrophication are limited by TP. Low concentration of Chl-a was in tributaries water body except Zhuxi river. Trophic states of tributaries were oligotropher to mesotropher. Utilizing the method of between-subjects effects tests, it indicated that spatial and seasonal distribution of nutrient factors is different in diverse seasons. The correlation of nutrient, organic contamination and Chl-a were researched. It indicated there was a significant positive correlation among Chl-a, nutrient and organic contamination. Fluxes load of nutrient and organic contamination was calculated by discharge and concentration of each tributary. It indicated that flux load of nutrient and organic contamination was mainly controlled by discharge. The flux load in flood season is higher than normal and dry season. The nutrient fluxes load of COD, potassium permanganate index, NH4^＋ -N, TN and TP are 1 172-6 701 g·s^-1 , 380-1 875 g·s^-1 , 40.1-172 g·s^-1 , 249-922 g·s^-1 and 9.97-50.5 g·s^-1 respectively. Pollution of tributaries in Three Gorges Area should be noticed.