摘要
青海湖是我国最大的湖泊,该流域生态系统健康对维系青藏高原生态安全具有重要意义.关于我国青藏高原区内大型湖泊的有色可溶性有机物(CDOM)组成与来源研究甚少,对青海湖流域开展CDOM的来源及特征研究对该湖水质保护及填补空白区的研究具有重要意义.通过两次青海湖流域采样并结合三维荧光光谱-平行因子分析法(EEMs-PARAFAC)分析了青海湖入湖河流和湖泊水体的CDOM组成特征、光学特性和可能来源.结果发现,湖泊内溶解性有机碳(DOC)浓度、a_(250)∶a_(365)和S_(275-295)均值均极显著高于入湖河流(P<0.0001,t-test,下同),而a_(350)、SUVA_(254)、I_(C)∶I_(T)和腐殖化指数HIX均值极显著小于入湖河流(P<0.0001),意味着湖泊内有机碳具有低芳香性特征,而入湖河流内CDOM则具有高芳香性且腐殖化程度高.通过平行因子分析法解析各水样的三维荧光光谱得到4个组分:陆源类腐殖质酸C1(E_(x)/E_(m)=255/428 nm)、微生物作用的类腐殖质酸C2[E_(x)/E_(m)=255(280)/428 nm]、类酪氨酸(E_(x)/E_(m)=270/316 nm)和类色氨酸C4(E_(x)/E_(m)=230/340 nm).就河源至河口连续体梯度而言,青海湖流域河源水体的溶解性有机碳(DOC)浓度、S_(275-295)和a_(250)∶a_(365)均小于下游河口区水体,表明从河流上游至下游过程中水体CDOM丰度增加而相对分子质量减少,陆源类腐殖质酸C1和主成分分析所得表征陆源输入的PC1均表现为河流显著大于湖泊(P<0.001),再次证明河流水体CDOM腐殖化程度高于湖泊水体.特别地,在泉吉河、沙柳河和哈尔盖河流域因下游河口冲积扇区域耕地比重较大,陆源类腐殖质C1组分的贡献比例相较于其他河流更高.
Lake Qinghai is the largest lake in China and is of great significance to maintain the ecological security of the Qinghai-Tibet Plateau.Few studies have been carried out to investigate the optical composition and source of chromophoric dissolved organic matter(CDOM)in large lakes on the Qinghai-Tibet Plateau.It is of great significance to study the source and optical dynamics of CDOM in Lake Qinghai watershed for water quality protection and filling in the gaps in the knowledge of CDOM variability in a remote area.Two sampling campaigns in the Lake Qinghai watershed were carried out,and excitation-emission matrices coupled with parallel factor analysis(EEMs-PARAFAC)were used to unravel the optical composition and the sources of CDOM.Our results indicated that the mean dissolved organic carbon(DOC)concentration,a_(250):a_(365),and the spectral slope of CDOM absorption S_(275-295) in the lake were significantly higher than that in the inflow river(P<0.0001,t-test),whereas the mean absorption coefficient of CDOM a_(350),humification index(HIX),fluorescence peak integration ratio I_(C):I_(T),and specific ultraviolet absorbance at _(254) nm SUVA_(254) of CDOM were shown to be lower in the lake than in the inflow river(P<0.0001),indicating that compared with the lake itself,CDOM in the inflow was humic-rich and highly aromatic.Four fluorescent components were obtained using PARAFAC,including a terrestrial human-like component C1,a microbial human-like component C2,a tyrosine-like C3,and a tryptophan-like C4.The mean DOC concentration,S_(275-295),and a_(250):a_(365)in the headwater streams of the Lake Qinghai watershed were lower than those in the downstream estuary,indicating that the CDOM abundance increased,and the molecular weight decreased,from the headwaters to the downstream river mouths.The mean of SUVA_(254),C1,and the first axis of principal component analysis were positively related to terrestrial input(i.e.,the PC1 values were significantly higher in rivers than in lakes(P<0.001)),indicating that the aromaticity of CDOM in rivers was higher than that in lakes.Particularly,the contribution of terrestrial humic-like C1 was higher in the Quanji River,Shaliu River,and Khargai River compared with that in other tributaries due to an intensified cultivated land use at the downstream estuary of these rivers.
作者
俞晓琴
孟先强
吴华武
陈慧敏
李宇阳
朱俊羽
郭燕妮
姚磊
YU Xiao-qin;MENG Xian-qiang;WU Hua-wu;CHEN Hui-min;LI Yu-yang;ZHU Jun-yu;GUO Yan-ni;YAO Lei(State Key Laboratory of Lake Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 210008,China;School of Geographic Sciences,Hunan Normal University,Changsha 410081,China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2022年第2期826-836,共11页
Environmental Science
基金
第二次青藏科考项目(2019QZKK0202)
中国科学院青年促进会项目(2021312)
中国科学院南京地理与湖泊研究所项目(E1SL002)
国家自然科学基金项目(41807362)
江苏省自然科学基金项目(BK20181104)。
