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	Source and quality of dissolved organic matter in streams are reflective to land use/land cover, climate seasonality and pCO2
	Zhang, Liuqing1,2,3; Xu, Y. Jun4,5; Li, Siyue1,6
	2023
摘要	Sources and quality of dissolved organic matter (DOM) in streams may be largely controlled by the landscape and season. In this study, we attempted to answer three critical questions: 1) Do land use/land cover (LULC) types affect DOM characteristics? 2) Is there a seasonal fluctuation in DOM components? 3) How do DOM quality and LULC types influence aqueous carbon dioxide partial pressure (pCO2). To achieve this, we investigated the fluorescence characteristics of DOM and its implication for pCO2 in three streams draining land with different urban intensities under distinctive dry and wet seasons. Four fluorescence components were identified, including two terrestrial humic-like components, one protein-like component and one microbial humic-like component. We found a significant positive relationship of the maximum fluorescence intensity (Fmax) of the four components and fluorescence index (FI370) with urbanization intensity in both the dry and wet seasons. The mean Fmax, biological index (BIX) and FI370 all exhibited an increasing trend from upstream to downstream in the stream with highest proportions of urban and cropland. The fluorescence characteristics were negatively related to proportion of forested land in the both seasons. The terrestrial humic-like DOM was dominating in the studied streams. Moreover, the seasonality altered the DOM composition, with protein-like component emerging only in stream waters during the dry season, while microbial humic-like component exclusively occurred during the wet season. pCO2 values were positively related to terrestrial humic-like and biological protein-like components, and urban land. The dry season had much higher pCO2 than the wet season. Results from the Partial Least Squares Path (PLS-PM) models further indicated that LULC types were important in mediating fluorescence DOM whilst pCO2 was more sensitive to the direct effect from FDOM dynamics. We conclude that DOM source and quality in streams are reflective to LULC and climate seasonality, and are good indicators of pCO2 via source tracer and quality of fluorescence components.
关键词	Land use land cover Seasonality Dissolved organic matter (DOM) Fluorescence DOM (FDOM) Three Gorges Reservoir Area (TGRA) Parallel factor analysis (PARAFAC)
DOI	10.1016/j.envres.2022.114608
发表期刊	ENVIRONMENTAL RESEARCH
ISSN	0013-9351
卷号	216页码:10
通讯作者	Li, Siyue(syli2006@163.com)
收录类别	SCI
WOS记录号	WOS:000883777800001
语种	英语