Effects of land use and nutrients on the characteristics of dissolved organic matter in the Nanchong Section of Jialing River, China in December 2019. Issue 2 (15th September 2021)

• Record Type: Journal Article
• Authors: Zhang, Liuqing; Zhu, Xiaohua; Huang, Xing; Liu, Chaorong; Yang, Yan
• Is Part Of: Water Supply. Volume 22:Issue 2(2022)
• Page Start: 1863
• Page End: 1875
• Publication Date: 2021-09-15
• Subjects: chromophoric dissolved organic matter (CDOM) -- dissolved organic matter (DOM) -- Jialing River -- nutrients -- parallel factor (PARAFAC) analysis -- urban land
• DOI: 10.2166/ws.2021.307
• Languages: English
• ISSNs: 1606-9749

Abstract

Abstract: Chromophoric dissolved organic matter (CDOM) in aquatic ecosystems can reflect the impacts of human activities on the carbon-cycling process. However, direct evidence of the combined effect of land use and anthropogenic nutrients on CDOM characteristics in river ecosystems is limited. Herein, we collected water samples from 18 sites in the Nanchong section of Jialing River in December 2019 to elucidate how the land use and nutrients affect the source and composition of CDOM through parallel factor (PARAFAC) analysis of excitation–emission matrices (EEMs). First, the absorption coefficient a 254 ( r 2 =0.29, p <0.01) and three fluorescence components (humic-like C1 and C2 and protein-like C3) ( r 2 =0.31–0.37, p <0.01) significantly increased with increased urban area, and the four parameters were higher in the urban area than in the suburbs ( p <0.05). The correlation between small-size CDOM molecule and cropland was positive ( p <0.01). Second, the increase in nutrient levels increased the a 254 ( r 2 =0.84 and 0.33, p <0.01) and three fluorescence components ( r 2 =0.30–0.84, p <0.01 or p <0.05). Third, allochthonous CDOM were prevalent in the Nanchong Section of Jialing River, and the proportions of C1 and C2 were 42 and 41%, respectively. Our findings indicated that the variability of source and composition of CDOM significantly depended on urbanization and increased nutrients in the Nanchong Section of Jialing River. HIGHLIGHTS: We found that (1) Terrestrial dissolved organic matter (DOM) input was the primary source in the Nanchong Section of Jialing River (2) Nutrients (i.e., TN and TP) and Urban land use enhanced inputs of allochthonous and autochthonous DOM. Our study highlights that increased urbanization significantly altered the source and composition of DOM and thus potentially affected the progress of the carbon cycle and aquatic system function of the Jialing River.