Spatial and temporal variability in nitrous oxide and methane emissions in urban riparian zones of the Pearl River Delta
2016
Zhang, Taiping | Huang, Xinyu | Yang, Yue | Li, Yuelin | Dahlgren, Randy A.
Spatial and temporal variability in nitrous oxide and methane emissions were quantified in three seasons using closed chambers in three riparian zone locations of three branches of the Pearl River, Guangzhou, China. The sampling sites were selected in a rapidly developing urban area of Guangzhou and represented a pollution gradient. The results show that urban riparian landscapes can be large source areas for CH₄ and N₂O, with fluxes of −0.035 ∼ 32.30 mg m⁻² h⁻¹ and −5.49 ∼ 37.31 μg m⁻² h⁻¹, respectively. River water quality, sediment texture, and NH₄-N and NO₃-N concentrations correlated with N₂O and CH₄ emission rates. The riparian zones of the more seriously polluted tributaries showed higher greenhouse gas fluxes than that of the less polluted main stem of the Pearl River. Rain events increased emissions of CH₄ by 6.5 ∼ 21.3 times and N₂O by 2.2 ∼ 5.7 times. The lower concentrations of heavy metals increased the activity of denitrifying enzymes while inhibited the methane producing pathways. This work demonstrates that rapidly developing urban areas are an important source of greenhouse gas emissions, which is conditioned by various environmental factors.
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