TY - JOUR
T1 - Wastewater treatment plant effluent inputs induce large biogeochemical changes during low flows in an intermittent stream but small changes in day-night patterns
AU - Bernal, Susana
AU - Drummond, Jennifer
AU - Castelar, Sara
AU - Gacia, Esperança
AU - Ribot, Miquel
AU - Martí, Eugènia
PY - 2020/4/20
Y1 - 2020/4/20
N2 - Wastewater treatment plant (WWTP) effluents alter stream water chemistry and metabolic activity. Yet, essential aspects influencing the biogeochemical response of receiving streams such as hydrology and diel oscillations of light and temperature remain largely unexplored. We measured day vs night water chemistry and in-stream net nutrient uptake velocity (Vf) in an intermittent forested stream, upstream and downstream of a WWTP effluent under contrasting hydrological conditions. The WWTP effluent negatively influenced stream water chemistry, especially during the dry period. Despite large diel oscillations in light inputs, day-night differences in nutrient and oxygen concentrations were small, suggesting that heterotrophic respiration drove stream metabolism with a minor contribution of gross primary production. The magnitude of Vf was similar between day and night at the two reaches. Yet, at the downstream reach, in-stream net DIN uptake occurred more often at night, and values of Vf for ammonia and nitrite indicated enhanced in-stream nitrification. The two reaches showed a small capacity to retain DIN and soluble reactive phosphorus from the water column. Positive values of in-stream net nutrient uptake (i.e. uptake > release) occurred mostly during the dry period, highlighting that in-stream biogeochemical processing can contribute to improve water quality in streams receiving point-sources effluents in regions with low water availability.
AB - Wastewater treatment plant (WWTP) effluents alter stream water chemistry and metabolic activity. Yet, essential aspects influencing the biogeochemical response of receiving streams such as hydrology and diel oscillations of light and temperature remain largely unexplored. We measured day vs night water chemistry and in-stream net nutrient uptake velocity (Vf) in an intermittent forested stream, upstream and downstream of a WWTP effluent under contrasting hydrological conditions. The WWTP effluent negatively influenced stream water chemistry, especially during the dry period. Despite large diel oscillations in light inputs, day-night differences in nutrient and oxygen concentrations were small, suggesting that heterotrophic respiration drove stream metabolism with a minor contribution of gross primary production. The magnitude of Vf was similar between day and night at the two reaches. Yet, at the downstream reach, in-stream net DIN uptake occurred more often at night, and values of Vf for ammonia and nitrite indicated enhanced in-stream nitrification. The two reaches showed a small capacity to retain DIN and soluble reactive phosphorus from the water column. Positive values of in-stream net nutrient uptake (i.e. uptake > release) occurred mostly during the dry period, highlighting that in-stream biogeochemical processing can contribute to improve water quality in streams receiving point-sources effluents in regions with low water availability.
KW - day-night cycles
KW - in-stream nutrient uptake
KW - intermittent stream
KW - nitrogen
KW - phosphorus
KW - wastewater treatment plant
UR - http://www.scopus.com/inward/record.url?scp=85078126504&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2020.136733
DO - 10.1016/j.scitotenv.2020.136733
M3 - Article
SN - 0048-9697
VL - 714
SP - 1
EP - 10
JO - Science of the Total Environment
JF - Science of the Total Environment
M1 - 136733
ER -