title: Fluorescent components and spatial patterns of chromophoric dissolved organic matters in Lake Taihu, a large shallow eutrophic lake in China.
abstract: Water samples at both surface and bottom layers were taken from 102 sites in Lake Taihu to study the fluorescent components and spatial patterns of chromophoric dissolved organic matters (CDOM). Three-dimensional excitation-emission matrix data obtained from the samples were analyzed by parallel factor approach in which four humic-like and two protein-like fluorescent components (named C1-C6) were identified. The results showed that fluorescence intensities were higher in the northern and western lake regions, and notable declines of fluorescence maxima (Fmax) were observed from the northwest to the center and then to the southeast of the lake. Calculated biological index (BIX) values ranged from 0.88 to 1.44 and humification index (HIX) values from 0.64 to 3.37 for all the samples. The spatial variations of BIX and HIX values suggested stronger allochthonous CDOM characteristics in Zhushan Bay and the western area and autochthonous characteristics in the southern and eastern areas. Vertically, the average Fmaxvalue of the surface samples was about 6 % less than that of the bottom samples, but noticeable variations existed among different sampling sites and components. These distribution characteristics of CDOM were mainly attributed to the spatial heterogeneity of sources and wind-induced transportation process. Interestingly, the C6 component (Exmax/Emmax= 250/455 nm) seemed to be unique in samples from Zhushan Bay and probably resulted from the discharge of the Taige River. Therefore, it could be used as an indicator of point-source discharge and a tracer to study the fate of CDOM in the lake.
authors: Key Laboratory for Mechanics in Fluid Solid Coupling Systems, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, China. yaobo@imech.ac.cn.
authors: Bo
authors: http://orcid.org/0000-0002-4465-4984
authors: B
authors: Yao
authors: State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
authors: Chunming
authors: C
authors: Hu
authors: Department of Mechanics, School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100081, China.
authors: Qingquan
authors: Q
authors: Liu
mesh_terms: D002681:China; D004784:Environmental Monitoring; D005453:Fluorescence; D060106:Lakes / Q000737:chemistry*; D008956:Models, Chemical; D009930:Organic Chemicals / Q000032:analysis*; D010860:Pigments, Biological / Q000032:analysis*; D013050:Spectrometry, Fluorescence; D014872:Water Movements; D060753:Water Quality
chemical_list: D009930:Organic Chemicals; D010860:Pigments, Biological
keywords: CDOM; Hydrodynamics; PARAFAC; Spatial heterogeneity; Vertical difference