Large Spatial Variations in Diffusive CH4 Fluxes from a Subtropical Coastal Reservoir Affected by Sewage Discharge in Southeast China

Ping Yang, Hong Yang, Jordi Sardans, Chuan Tong*, Guanghui Zhao, Josep Peñuelas*, Ling Li, Yifei Zhang, Lishan Tan, Kwok Pan Chun, Derrick Y. F. Lai*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

Coastal reservoirs are potentially CH4 emission hotspots owing to their biogeochemical role as the sinks of anthropogenic carbon and nutrients. Yet, the fine-scale spatial variations in CH4 concentrations and fluxes in coastal reservoirs remain poorly understood, hampering an accurate determination of reservoir CH4 budgets. In this study, we examined the spatial variability of diffusive CH4 fluxes and their drivers at a subtropical coastal reservoir in southeast China using high spatial resolution measurements of dissolved CHconcentrations and physicochemical properties of the surface water. Overall, this reservoir acted as a consistent source of atmospheric CH4, with a mean diffusive flux of 16.1 μmol m-2 h-1. The diffusive CHflux at the reservoir demonstrated considerable spatial variations, with the coefficients of variation ranging between 199 and 426% over the three seasons. The shallow water zone (comprising 23% of the reservoir area) had a disproportionately high contribution (56%) to the whole-reservoir diffusive CHemissions. Moreover, the mean CHflux in the sewage-affected sectors was significantly higher than that in the nonsewage-affected sectors. The results of bootstrap analysis further showed that increasing the sample size from 10 to 100 significantly reduced the relative standard deviation of mean diffusive CHflux from 73.7 to 3.4%. Our findings highlighted the role of sewage in governing the spatial variations in reservoir CHemissions and the importance of high spatial resolution data to improve the reliability of flux estimates for assessing the contribution of reservoirs to the regional and global CHbudgets.

Original languageEnglish
Pages (from-to)14192-14203
Number of pages12
JournalEnvironmental Science & Technology
Volume54
Issue number22
DOIs
Publication statusPublished - 17 Nov 2020

Scopus Subject Areas

  • Chemistry(all)
  • Environmental Chemistry

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