Chen Jia, Li Zhong-Wu, Jin Chang-Sheng, Wen Jia-Jun, Nie Xiao-Dong, Wang Lei
College of Environmental Science and Engineering, Hunan University, Changsha 410082, China.
School of Geographic Sciences, Hunan Normal University, Changsha 410081, China.
Huan Jing Ke Xue. 2022 Sep 8;43(9):4566-4575. doi: 10.13227/j.hjkx.202112090.
The characteristics and sources of DOM in sediments are significantly affected by fluctuations in lake water levels. However, the impact of spatial differences on water levels remain unclear. Here, 36 sediment samples were collected from the flood passage and coastal beach of East Dongting Lake. The differences in the composition and source of DOM in sediments under perennial inundation and seasonal inundation were studied using UV-visible absorbance (UV-Vis) and fluorescent excitation-emission matrix (EEM)-parallel factor analysis (PARAFAC). Three fluorescent components of DOM in the sediment were identified. The relative abundance of protein-like components was as high as (72.95±8.94)%, including tryptophan (C2) and tyrosine (C3). However, the humic-like component (C1) abundance was (27.05±8.94)%. Compared with that in perennial inundation, DOM in seasonal inundation had a higher and lower relative abundance of protein-like components and humic-like components, respectively. Further, the aromatic and hydrophobic components were higher in perennial inundation, showing a spatial pattern of the middle>entrance>outlet of the lake, which was more conducive to the migration of pollutants. The high FI (1.93) and BIX (0.91) and low HIX (1.57) indicated that the DOM in sediments had the mixed characteristics of being mainly endogenic and relatively weakly terrigenous. This was mainly influenced by human input and sediment characteristics. The direct effect of sewage discharge was intensified by sediment exposure in the seasonal inundation zone. Additionally, the contents of clay and total nitrogen (TN) were significantly positively correlated with FI, indicating that high nutrients and clay in sediments enhanced the endogenous input of DOM (FI>1.9). The perennial inundation zone was influenced by external runoff input. At the same time, the pH and C/N were significantly positively correlated with HIX and C1, indicating that DOM in the sediments had higher terrigenic characteristics (HIX=1.38±0.57) than those in the seasonal inundation zone owing to the alkaline environment (pH>7.5) and runoff input. The results above revealed the relevant theories of the response of DOM in sediment to water quality and pollution in the process of hydrology and human activities and provide a scientific basis for the prevention and control of sediment pollution in lakes.
沉积物中溶解性有机质（DOM）的特征和来源受湖泊水位波动的显著影响。然而，水位的空间差异所产生的影响仍不明确。在此，从东洞庭湖的泄洪通道和湖滨滩地采集了36个沉积物样本。利用紫外可见吸光度（UV-Vis）和荧光激发-发射矩阵（EEM）-平行因子分析（PARAFAC）研究了常年淹水和季节性淹水条件下沉积物中DOM的组成和来源差异。识别出沉积物中DOM的三种荧光组分。类蛋白组分的相对丰度高达（72.95±8.94）%，包括色氨酸（C2）和酪氨酸（C3）。然而，类腐殖质组分（C1）的丰度为（27.05±8.94）%。与常年淹水相比，季节性淹水条件下DOM的类蛋白组分和类腐殖质组分的相对丰度分别更高和更低。此外，常年淹水条件下芳香族和疏水性组分更高，呈现出湖心>湖口>湖尾的空间格局，这更有利于污染物的迁移。较高的荧光指数（FI，1.93）和生物指数（BIX，0.91）以及较低的腐殖化指数（HIX，1.57）表明沉积物中的DOM具有以内源为主且陆源相对较弱的混合特征。这主要受人类输入和沉积物特征的影响。季节性淹水区沉积物暴露加剧了污水排放的直接影响。此外，黏土和总氮（TN）含量与FI显著正相关，表明沉积物中高养分和黏土增强了DOM的内源输入（FI>1.9）。常年淹水区受外源径流输入影响。同时，pH值和碳氮比与HIX和C1显著正相关，表明由于碱性环境（pH>7.5）和径流输入，沉积物中的DOM比季节性淹水区具有更高的陆源特征（HIX=1.38±0.57）。上述结果揭示了沉积物中DOM在水文和人类活动过程中对水质和污染响应的相关理论，为湖泊沉积物污染防治提供了科学依据。
