中文版 | English
CSpace
Hot spot of CH4 production and diffusive flux in rivers with high urbanization
Tang, Wei1; Xu, Y. Jun2,3; Ma, Yongmei1; Maher, Damien T.4; Li, Siyue5
2021-10-01
摘要Rivers and streams play a central role in global carbon budget, but our knowledge is limited on the magnitude and extent of urbanization influence on riverine methane (CH4) dynamics. In this study, we investigated dissolved CH4 (dCH(4)) concentration and CH4 diffusive fluxes in 27 river segments of two 4th-order and three 3rd order tributary rivers to the Yangtze River in China, which drained land areas with varied urbanization intensities. We found that urban development was the key factor responsible for high fluvial dCH(4) concentration and diffusive flux, exceeding the influence of agricultural farming, and these headwater rivers were oversaturated in CH4 with respect to atmospheric equilibrium. dCH(4) concentration (3546 +/- 6770 nmol L-1) in the river segments draining higher urban area (20% <= urban land proportion <= 46%) was 5-6 times higher than those (615 +/- 627 nmol L-1 and 764 +/- 708 nmol L-1) in the river segments draining less urban area (0.1% <= urban land proportion < 2% and 2 <= urban land proportion < 20%). River segments draining higher urban area also acted as important sources of CH4 to the atmosphere (8.93 +/- 14.29 mmol m(-2) d(-1)). Total nitrogen (TN) concentration in river water showed the best prediction capacity when compared to other water parameters. Based on urban land use grouping, nutrient elements could predict dCH(4) well in rivers draining higher urban areas (urban >= 2%), which also reflected the lateral input of pollutants (TN, ammonia nitrogen, and total phosphorus). River bottom sediment fraction contributed to trapping organic matter and nutrients as well as to oxic and anoxic conditions, thereby determining reach-scale spatial patterns of dCH(4) concentration. These findings highlight that combining distal geomorphic and hydrologic drivers can be effective in determining the relationship between riverine CH4 and the proximal controls (e.g., nutrients, dissolved oxygen, dissolved organic carbon), as well as in identifying their key drivers. Being rapid urbanization a common feature of catchments worldwide, our results suggest riverine CH4 emissions will increase into the future.
关键词Riverine dissolved CH4 CH4 diffusive fluxes Urbanization Low-order streams Three Gorges Reservoir (TGR) catchment
DOI10.1016/j.watres.2021.117624
发表期刊WATER RESEARCH
ISSN0043-1354
卷号204页码:11
通讯作者Li, Siyue(syli2006@163.com)
收录类别SCI
WOS记录号WOS:000697775900008
语种英语