基于CDOM吸收特性的东北地区水库DOC浓度遥感估算

有色溶解性有机物(CDOM)广泛存在于水体中，占溶解有机碳(DOC)10%～90%，其浓度影响水环境碳循环过程、污染物质迁移以及水生生物群落的结构和功能。为分析东北地区水库DOC碳循环情况，本文于2015—2020年对第二松花江流域典型水库白山水库和丰满水库进行5次现场观测和室内实验，在分析CDOM吸收特性的基础上，基于Landsat系列卫星利用波段比值法建立CDOM浓度反演模型(R²=0.82)，根据实测值CDOM与DOC的强相关性(R²=0.78)，进而估算水库DOC浓度。结果表明：(1)利用野外实测数据和Landsat系列卫星能够对东北内陆水库CDOM浓度进行良好反演，(2)2000—2020年白山水库和丰满水库年际CDOM和DOC浓度变化不大，在2010年之后表现出轻微上升趋势，CDOM浓度从支流和干流的汇入到主库区呈现逐渐减少趋势，(3)白山水库和丰满水库M值(CDOM在250和365 nm处吸收系数比值)和S_275～295(CDOM在275～295 nm波段处的吸收光谱的斜率)较小、SUVA_254<...

Remote sensing estimation of DOC concentration of reservoirs in Northeast China based on CDOM absorption

Colored dissolved organic matter (CDOM) widely exists in water, accounting for 10%-90% of dissolved organic carbon (DOC). In order to analyze the distributions of DOC concentrations in the reservoirs in the northeastern China, five field campaigns were carried out in Baishan Reservoir and Fengman Reservoir in the Songhua River Basin from 2015 to 2020. Based on the analysis of the absorption characteristics of CDOM coefficient (355 nm), the remote sensing inversion model of CDOM absorption coefficient at 355nm (R²=0.82) is established by band ratio method based on Landsat series satellites and the DOC concentrations of the reservoirs are estimated according to the strong correlations between CDOM and DOC. The results show that: The CDOM concentrations of inland reservoirs in the northeastern China can be well retrieved by using the in-situ sampling data and Landsat datasets; The annual spatial-temporal distributions of CDOM and DOC concentrations in the Baishan Reservoir and the Fengman Reservoir from 2000 to 2020 are with low fluctuations, and the concentration of CDOM and DOC appeared an upward trend after 2010. The Baishan Reservoir and the Fengman Reservoir have lower M values (the ratio of absorption coefficient of CDOM at 250 nm and 365 nm) and S_275-295 (the slope of the absorption spectrum of CDOM at the 275-295 nm), and higher SUVA₂₅₄ (the ratio of CDOM absorption coefficient at 254 nm to DOC concentration), indicating that the humic contents in the CDOM compositions are higher, and tend to be consisted of terrigenous macromolecules. Using multiple regression analysis method to analyze the annual driving factors of CDOM distributions of the reservoirs is mainly affected by rainfalls, fertilizer applications and sewage discharges. Finally, this study enriches the understanding of the variations of CDOM concentrations in typical reservoirs in the northeastern China and provides a reference for the construction of DOC inversion models and contributes to the accuracy estimation of DOC concentrations.