TY - JOUR
T1 - Groundwater-controlled phosphorus release and transport from sandy aquifer into lake
AU - Kazmierczak, Jolanta
AU - Postma, Dieke
AU - Müller, Sascha
AU - Jessen, Søren
AU - Nilsson, Bertel
AU - Czekaj, Joanna
AU - Engesgaard, Peter
N1 - Funding Information:
The study was supported by Villum Kann Rasmussen Center for Excellence, the Center for Lake Restoration (CLEAR, Denmark). Slawomir Kazmierczak and students from the University of Copenhagen are thanked for help during the field surveys.
Funding Information:
The study was supported by Villum Kann Rasmussen Center for Excellence, the Center for Lake Restoration (CLEAR, Denmark). Slawomir Kazmierczak and students from the University of Copenhagen are thanked for help during the field surveys.
Publisher Copyright:
© 2020 The Authors. Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography.
PY - 2020/9/1
Y1 - 2020/9/1
N2 - Awareness of groundwater-borne dissolved inorganic phosphorus (DIP) loadings into lakes and its role in lake eutrophication is increasing, albeit DIP of natural origin is often ignored. Release of geogenic DIP from an adjacent aquifer and its transport with groundwater into a eutrophic lake is described by combining hydrogeochemical data collected in this study (sampling of piezometers, hydrogeochemical profiles, and seepage meters) with groundwater flow and discharge rates from earlier studies. The major part of the DIP that entered the lake with discharging groundwater was mobilized from iron hydroxides reduced by organic matter buried in the sediments of the old lake bottom. This is indicated by the correlation between DIP and ferrous iron (Fe2+) concentrations, with a DIP/Fe2+ molar ratio of 0.06, and an increase in pH. One-dimensional reactive transport modeling indicated that high discharge rates (' 0.1 m d−1) of anoxic groundwater upwelling in areas adjacent to the lakeshore prevent downward diffusion of oxygen into the aquifer and do not leave enough time for DIP to become rebounding to the mineral phases at the sediment-water interface. The groundwater-controlled DIP input into the lake calculated along a two-dimensional cross-section averaged 0.01 mol DIP m−2 yr−1. A 2 m wide offshore high discharge zone delivered approximately 13% of the DIP into the lake. The continuous, external loading of geogenic DIP sustains lake eutrophication and explains the failure of two previous lake restoration attempts.
AB - Awareness of groundwater-borne dissolved inorganic phosphorus (DIP) loadings into lakes and its role in lake eutrophication is increasing, albeit DIP of natural origin is often ignored. Release of geogenic DIP from an adjacent aquifer and its transport with groundwater into a eutrophic lake is described by combining hydrogeochemical data collected in this study (sampling of piezometers, hydrogeochemical profiles, and seepage meters) with groundwater flow and discharge rates from earlier studies. The major part of the DIP that entered the lake with discharging groundwater was mobilized from iron hydroxides reduced by organic matter buried in the sediments of the old lake bottom. This is indicated by the correlation between DIP and ferrous iron (Fe2+) concentrations, with a DIP/Fe2+ molar ratio of 0.06, and an increase in pH. One-dimensional reactive transport modeling indicated that high discharge rates (' 0.1 m d−1) of anoxic groundwater upwelling in areas adjacent to the lakeshore prevent downward diffusion of oxygen into the aquifer and do not leave enough time for DIP to become rebounding to the mineral phases at the sediment-water interface. The groundwater-controlled DIP input into the lake calculated along a two-dimensional cross-section averaged 0.01 mol DIP m−2 yr−1. A 2 m wide offshore high discharge zone delivered approximately 13% of the DIP into the lake. The continuous, external loading of geogenic DIP sustains lake eutrophication and explains the failure of two previous lake restoration attempts.
UR - http://www.scopus.com/inward/record.url?scp=85083044414&partnerID=8YFLogxK
U2 - 10.1002/lno.11447
DO - 10.1002/lno.11447
M3 - Article
AN - SCOPUS:85083044414
SN - 0024-3590
VL - 65
SP - 2188
EP - 2204
JO - Limnology and Oceanography
JF - Limnology and Oceanography
IS - 9
ER -