Urban rivers are hotspots of riverine greenhouse gas (N2O, CH4, CO2) emissions in the mixed-landscape chaohu lake basin

Zhang, Wangshou; Li, Hengpeng; Xiao, Qitao; Li, Xinyan

doi:10.1016/j.watres.2020.116624

Cited by 102 publications

(72 citation statements)

References 66 publications

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“…The density and biomass of filter-feeding cladocerans and copepods in the Chaohu Lake were higher than those in the rivers, possibly because the cyanobacterial bloom in the Chaohu Lake provides rich food sources for filter-feeding cladocerans and copepods. Zhang et al [43] divided the seven rivers in this study into different river types according to the landscape composition of the river basin: the HBR is the forest river type, the NFR and PR are the urban river type, the BSSR and ZR are the agricultural river type, the ZGR is the mixed river type, the YXR estuary and upstream are the mixed river type, and the YXR midstream and downstream are the forest river type. In this study, Chaohu Lake and the seven rivers showed an obvious spatial distribution pattern in the nutrient gradient.…”

Section: Discussionmentioning

confidence: 99%

Distribution of Zooplankton Functional Groups in the Chaohu Lake Basin, China

Chen

et al. 2022

Water

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To analyze the structural characteristics of zooplankton functional groups (ZFGs) and their correlation with environmental physicochemical factors in the Chaohu Lake Basin, water samples were collected from October 2019 to July 2020, and the zooplankton species and ZFGs were investigated. A total of 250 species, including 88 protozoa, 115 rotifers, 28 cladocerans, and 19 copepod species, were detected and divided into 16 ZFGs. The ZFGs exhibited obvious spatiotemporal heterogeneity. ZFGs in the Chaohu Lake were notably different from those in rivers and were different between the rivers. In the ecosystem, network analysis showed that protozoan algae/protozoan bacteria (PA/PB), rotifer particle filter (RF), and rotifer small predator (RSG) were important in the spring, summer, and autumn that and small zooplankton filter (SCF) was important in spring, autumn, and winter, while the importance of other ZFGs changed with seasons. Redundancy analysis showed that the environmental factors with a strong correlation between the ZFG compositions differed in each season. Different ZFGs exhibited different correlations with environmental factors. This study showed that ZFGs were closely related to environmental factors and that functional traits can reflect responses to changes in the water environment.

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Section: Discussionmentioning

confidence: 99%

Distribution of Zooplankton Functional Groups in the Chaohu Lake Basin, China

Chen

et al. 2022

Water

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“…The following 24‐hr period, corresponding to conditions on the day of gas flux sampling (October 21, 2020), was then analyzed, with the measured stage profile assigned as the seepage face boundary. The diffuse flux of gaseous N 2 O to the atmosphere ( F N2O ), which relates modeled dissolved N 2 O concentrations to measured gaseous fluxes, was calculated as (Zhang et al., 2021):

{F}_{{N}_{2}O}=k({C}_{gw}-{C}_{eq}),

where k is the gas transfer velocity (m/d), C gw is the dissolved N 2 O concentration in the groundwater, and C eq is the dissolved N 2 O concentration in equilibrium the ambient atmosphere. Ambient conditions were taken as the average air temperature measured during gas sampling (21.5°C) and standard atmospheric pressure (101,325 Pa).…”

Section: Methodsmentioning

confidence: 99%

Spatiotemporal Dynamics of Nitrous Oxide Emission Hotspots in Heterogeneous Riparian Sediments

Wallace

Tonina

McGarr

et al. 2021

Water Resources Research

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Nitrous oxide (N2O) is a potent ozone‐depleting greenhouse gas produced by incomplete denitrification. Recent works on riverine N2O emissions focus mainly on contributions from in‐channel, benthic, and fluvial hyporheic environments under assumptions of steady‐state conditions and homogeneous sediment hydraulic conductivity (K). However, riparian floodplains are also a potentially important N2O source characterized by complex sediment heterogeneity and dynamic surface and groundwater interactions. We use numerical flow and reactive transport models to investigate the influence of complex sedimentary architecture and high‐flow events (e.g., storms) on N2O production. We interpret the correlation between flow and solute fields with the flow topological Okubo‐Weiss metric (OW) and the scalar dissipation rate weighted by soil organic matter (OM) fraction and soil saturation. We model a heterogeneous riparian floodplain based on field observations from the Theis Environmental Monitoring and Modeling Site, Ohio, USA. N2O production is greatest within intermediate‐K sediments (e.g., sands) where denitrification rates are highest, and emissions increase by more than an order of magnitude during storms. Sensitivity analysis reveals that the denitrification rate is most influential for N2O flux, accounting for nearly 46% of the variance in production rates. Denitrification rates adapt to spatial changes in the flow topology (measured by OW) related to sediment heterogeneity and are strongly influenced by subsurface mixing dynamics. Mixing is greatest in shear strain‐dominated regions, while vorticity promotes OM dissolution and prolongs residence times. Accurate lithologic representation is imperative for characterizing subsurface N2O production dynamics, especially given growing concern regarding climate change driven hydrologic changes within watersheds worldwide.

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“…The soil CO 2 could be easily transported to rivers and thus increase the pCO 2 , while the liable DOC could be decomposed rapidly after entering the rivers due to their sensitivity to in-stream metabolism (Lambert et al, 2017;Li et al, 2019). Meanwhile, the input of wastewater with high organic matter concentration from urban areas could also contribute to an increase in riverine pCO 2 (Xuan et al, 2020;Zhang et al, 2021). Our results showed increasing pCO 2 from forest-dominated streams in the UDJRB relative to those in agricultural and urban-impacted catchments in the MDJRB and LDJRB (Fig.…”

Section: Underlying Processes Of Pco 2 Dynamicsmentioning

confidence: 99%

“…The Dong River (DJR), located in subtropical south China, is one of the three tributaries of the Pearl River. Previous studies on riverine carbon transport and emissions in the Pearl River system mainly focused on the Xi River, which is characterized by widely distributed carbonate rocks, and the estuary area of the Pearl River delta (Yao et al, 2007;Zhang et al, 2015Zhang et al, , 2019Zhang et al, , 2021. Although some studies on chemical weathering and dissolved inorganic carbon (DIC) transport in the Dong River basin (DJRB) have been conducted (Tao et al, 2011;Fu et al, 2014), there is still a lack of understanding of the characteristics of catchment-wide CO 2 emissions from the DJRB.…”

Section: Introductionmentioning

confidence: 99%

Spatial and temporal variability of pCO2 and CO2 emissions from the Dong River in south China

Liu

Tian²,

Shih

et al. 2021

Biogeosciences

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Abstract. CO2 efflux at the water–air interface is an essential component of the riverine carbon cycle. However, the lack of spatially resolved CO2 emission measurements prohibits reliable estimation of the global riverine CO2 emissions. By deploying floating chambers, seasonal changes in river water CO2 partial pressure (pCO2) and CO2 emissions from the Dong River in south China were investigated. Spatial and temporal patterns of pCO2 were mainly affected by terrestrial carbon inputs (i.e., organic and inorganic carbon) and in-stream metabolism, both of which varied due to different land cover, catchment topography, and seasonality of precipitation and temperature. Temperature-normalized gas transfer velocity (k600) in small rivers was 8.29 ± 11.29 and 4.90 ± 3.82 m d−1 for the wet season and dry season, respectively, which was nearly 70 % higher than that of large rivers (3.90 ± 5.55 m d−1 during the wet season and 2.25 ± 1.61 m d−1 during the dry season). A significant correlation was observed between k600 and flow velocity but not wind speed regardless of river size. Most of the surveyed rivers were a net CO2 source while exhibiting substantial seasonal variations. The mean CO2 flux was 300.1 and 264.2 mmol m−2 d−1 during the wet season for large and small rivers, respectively, 2-fold larger than that during the dry season. However, no significant difference in CO2 flux was observed between small and large rivers. The absence of commonly observed higher CO2 fluxes in small rivers could be associated with the depletion effect caused by abundant and consistent precipitation in this subtropical monsoon catchment.

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Urban rivers are hotspots of riverine greenhouse gas (N2O, CH4, CO2) emissions in the mixed-landscape chaohu lake basin

Cited by 102 publications

References 66 publications

Distribution of Zooplankton Functional Groups in the Chaohu Lake Basin, China

Distribution of Zooplankton Functional Groups in the Chaohu Lake Basin, China

Spatiotemporal Dynamics of Nitrous Oxide Emission Hotspots in Heterogeneous Riparian Sediments

Spatial and temporal variability of <i>p</i>CO<sub>2</sub> and CO<sub>2</sub> emissions from the Dong River in south China

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Urban rivers are hotspots of riverine greenhouse gas (N2O, CH4, CO2) emissions in the mixed-landscape chaohu lake basin

Cited by 102 publications

References 66 publications

Distribution of Zooplankton Functional Groups in the Chaohu Lake Basin, China

Distribution of Zooplankton Functional Groups in the Chaohu Lake Basin, China

Spatiotemporal Dynamics of Nitrous Oxide Emission Hotspots in Heterogeneous Riparian Sediments

Spatial and temporal variability of &lt;i&gt;p&lt;/i&gt;CO&lt;sub&gt;2&lt;/sub&gt; and CO&lt;sub&gt;2&lt;/sub&gt; emissions from the Dong River in south China

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Spatial and temporal variability of <i>p</i>CO<sub>2</sub> and CO<sub>2</sub> emissions from the Dong River in south China