三峡库区水体溶解性有机物和颗粒物垂直分布特征及来源分析

Vertical Variation and Sources of Dissolved Organic Matter and Particulate Matter in Waters Three Gorges Reservoir

基于3年的野外调查数据,运用平行因子法(PARAFAC)解析三维荧光光谱(EEMs),对三峡库区(百岁溪、九畹溪、沙镇溪和神农溪)水体中溶解有机物(CDOM)的垂直分布特征及来源进行了分析。结果表明:三峡库区POC和DOC含量具有相似的垂直分布特征,百岁溪、九畹溪、沙镇溪和神农溪POC和DOC含量随水深的增加而逐渐降低,其中表层最大,表层以下急剧降低,3 m以下降低趋势区域缓和,10 m处POC和DOC含量基本相等。其中相同水深基本表现为:百岁溪>九畹溪>沙镇溪>神农溪,局部有所波动。三峡库区营养盐垂直分布特征较为一致,其中百岁溪、九畹溪、沙镇溪和神农溪TP、TN、NH+4和NO-3含量随水深的增加而逐渐降低,其中表层最大,表层以下急剧降低,3 m以下降低趋势区域缓和,10 m处TP、TN、NH+4和NO-3含量基本相等。其中相同水深基本表现为:百岁溪>九畹溪>沙镇溪>神农溪,局部有所波动。三峡库区水质较好,总体为Ⅱ~Ⅲ类,其中TLI指数依次表现为百岁溪>九畹溪>沙镇溪>神农溪,百岁溪属于富营养级,主要是由于N含量超标,九畹溪、沙镇溪属于中营养级,神农溪属于轻度富营养。综合营养状态指数均值为35,属于中营养水平。百岁溪、九畹溪、沙镇溪、神农溪CDOM吸收系数a(280)和a(350)均表现为百岁溪<九畹溪<沙镇溪<神农溪。回归分析显示:百岁溪和沙镇溪POC和DOC与CDOM吸收系数a(280)呈显著线性相关(p<0.01);九畹溪和神农溪POC和DOC与CDOM吸收系数a(350)呈显著线性相关(p<0.01)。三峡库区荧光指数(FI)在1.32~1.43之间,均值为1.39,说明三峡库区陆源占主要贡献。生物指数(BIX)在1.03~1.14之间,说明三峡库区CDOM主要由生物细菌活动产生。腐殖化指数(HIX)在1.62~1.97之间,说明三峡库区CDOM主要由生物细菌活动产生,与BIX指数一致。由此说明三峡库区CDOM来源于自生微生物、藻类等新近自生源。

Based on 3-year field survey data,three dimensional fluorescence spectra(EEMs)are analyzed by PARAFAC,and the vertical distribution characteristics and source of CDOM in Three Gorges Reservoir Area(Baishuixi,Jiuwanxi,Shazhunxi and Shennongxi)are analyzed.Results show that the three gorges reservoir area of DOC and POC content with similar characteristics of vertical distribution of 0 to 10 m centenarians creek,drifting at Jiuwanxi,sand town creek and Shennong Xi DOC and POC content gradually decrease with the increase in the depth of the water,the surface layer,the largest surface sharply reduce.The same water depth is basically expressed as follows:100 years old stream>nine wan stream>sand town stream>shennong stream,local fluctuations.Nutrient vertical distribution characteristics of the three gorges reservoir is relatively consistent,with 0 to 10 m centenarians creek,drifting at Jiuwanxi,sand town creek and Shennong Xi TP,TN,NH+4 and NO-3 content gradually decreases with the increase in the depth of the water,the surface layer,the largest surface sharply decreases,reduce trend area below the 3,10 m in TP,TN,NH+4 and NO-3 content basic equal.The same water depth is basically expressed as follows:Baisui stream>Jiuwan stream>sand town stream>Shennong stream,local fluctuations.The three gorges reservoir area water quality is better,overallⅡ~Ⅲclasses,including TLI index in performance for drifting at Baisui Stream>Jiuwan Stream>sand town stream>Shennong Stream,centenarians creek to eutrophication level,mainly because of the excessive concentration of N,drifting at Jiuwanxi,belongs to the trophic level in the sand town creek,Shennong Xi belongs to light eutrophication.The mean value of the comprehensive nutrition status index is 35,belonging to medium nutrition level.The CDOM absorption coefficient a(280)and a(350)of Baisui Stream,Jiuwan Stream,Shazhen Stream and Shennong Stream are all expressed as Baisui Stream<Jiuwan Stream<Shazhen Stream<Shennong Stream.Regression analysis show that POC and DOC of Baishuixi and Shazzhenxi has significant linear correlation with CDOM absorption coefficient a(280)(p<0.01).Nine Wanxi and Shennongxi POC and DOC have significant linear correlation with CDOM absorption coefficient a(350)(p<0.01).The fluorescence index(FI)of the Three Gorges Reservoir area ranges from 1.32 to 1.43,with an average value of 1.39,indicating that terrestrial sources accounts for the major contribution in the three Gorges Reservoir area.Biological index(BIX)is between 1.03 and 1.14,indicating that CDOM in the Three Gorges Reservoir area is mainly generated by biological and bacterial activities.The humification index(HIX)is between 1.62 and 1.97,indicating that the CDOM in the Three Gorges Reservoir Area is mainly generated by biological and bacterial activities,which is consistent with the BIX index.This indicates that the CDOM in the Three Gorges Reservoir Area is derived from autogenous microorganisms,algae and other recent autogenous sources.