TY - JOUR
T1 - Effects of stream DO and DOC on streambed respiration under varying groundwater upwelling conditions
AU - Li, Jiaqi
AU - Xie, Yueqing
AU - Wu, Liwen
AU - Wang, Chuan
N1 - Publisher Copyright:
© 2024 Elsevier B.V.
PY - 2024/12
Y1 - 2024/12
N2 - Streambed respiration comprises aerobic respiration (AR) and denitrification (DN). It plays an important role in maintaining stream water quality and stream carbon and nitrogen balances. Under gaining stream conditions, dissolved oxygen (DO) and dissolved organic carbon (DOC) in a stream can still enter streambed to fuel respiration through hyporheic flow and diffusion. In this study, we established theoretical and field-based reactive transport models to quantify the effect of upwelling groundwater, stream DO and DOC on biogeochemical reactions. Modeling results show that enhanced dispersion of DO and DOC reinforces streambed respiration mostly within the thickness of 0.4 m. Stream DO affects AR and DN in opposite manners. As stream DO concentration increases from 3.2 to 16 mg L-1, CO2 efflux increases by 120%, while N2 efflux decreases by 12%. As stream DOC concentration increases by 5 times, both the CO2 efflux and N2 efflux increase by 17% and 3%, respectively. Groundwater flux affects the extent and efficiency of streambed respiration. As groundwater flux increases, both the supply of substrates for AR and the CO2 efflux increase. Meanwhile, the substrate residence time decreases, leading to retarded DO consumption by AR and so the decrease in N2 efflux. Field-based modeling indicates that CO2 efflux of streambed varied from 5.08 to 8.26 g m-2 d-1, contributing to stream CO2 emission. Overall, this research sheds new light on controls of stream chemistry and groundwater upwelling on streambed respiration.
AB - Streambed respiration comprises aerobic respiration (AR) and denitrification (DN). It plays an important role in maintaining stream water quality and stream carbon and nitrogen balances. Under gaining stream conditions, dissolved oxygen (DO) and dissolved organic carbon (DOC) in a stream can still enter streambed to fuel respiration through hyporheic flow and diffusion. In this study, we established theoretical and field-based reactive transport models to quantify the effect of upwelling groundwater, stream DO and DOC on biogeochemical reactions. Modeling results show that enhanced dispersion of DO and DOC reinforces streambed respiration mostly within the thickness of 0.4 m. Stream DO affects AR and DN in opposite manners. As stream DO concentration increases from 3.2 to 16 mg L-1, CO2 efflux increases by 120%, while N2 efflux decreases by 12%. As stream DOC concentration increases by 5 times, both the CO2 efflux and N2 efflux increase by 17% and 3%, respectively. Groundwater flux affects the extent and efficiency of streambed respiration. As groundwater flux increases, both the supply of substrates for AR and the CO2 efflux increase. Meanwhile, the substrate residence time decreases, leading to retarded DO consumption by AR and so the decrease in N2 efflux. Field-based modeling indicates that CO2 efflux of streambed varied from 5.08 to 8.26 g m-2 d-1, contributing to stream CO2 emission. Overall, this research sheds new light on controls of stream chemistry and groundwater upwelling on streambed respiration.
KW - Aerobic respiration
KW - Denitrification
KW - Diffusion
KW - Groundwater upwelling
KW - Headwater
KW - Streambed
UR - http://www.scopus.com/inward/record.url?scp=85212544203&partnerID=8YFLogxK
U2 - 10.1016/j.jhydrol.2024.132506
DO - 10.1016/j.jhydrol.2024.132506
M3 - Article
AN - SCOPUS:85212544203
SN - 0022-1694
VL - 650
JO - Journal of Hydrology
JF - Journal of Hydrology
M1 - 132506
ER -