TY - JOUR
T1 - Dissolved inorganic geogenic phosphorus load to a groundwater-fed lake: Implications of terrestrial phosphorus cycling by groundwater
AU - Nisbeth, C.S.
AU - Kidmose, J.
AU - Weckström, K.
AU - Reitzel, K.
AU - Odgaard, B.V.
AU - Bennike, O.
AU - Thorling, L.
AU - McGowan, S.
AU - Schomacker, A.
AU - Juul Kristensen, D.L.
AU - Jessen, S.
N1 - Funding details: Geocenter Danmark, 6-2015
Funding details: Københavns Universitet, KU
Funding text 1: This research was funded by GeoCenter Denmark, grant number 6-2015.The authors are thankful to the estate of Brahetrolleborg and Catharina Reventlow-Mourier for kindly providing access to N?rres?. Thanks are also given to J?rg Lewandowski (IGB, Berlin) and three anonymous reviewers for providing thorough and critical comments to the manuscript. We further thank Marie-Louise Siggaard-Andersen (Globe Institute, University of Copenhagen) for assistance in the paleolimnological analysis, Anne Thoisen (IGN) for her assistance in the hydrogeochemical laboratory, Ingelise M?ller Balling (GEUS) for sharing her expertise regarding the interpretation of the ERT profiles, Aia A. Eriksen and Hans Henrik Havn for their supporting works, Tai Lund J?rgensen for his proof reading, and Peter Engesgaard (IGN) for his good advice and assistance during especially the early part of the study.
Funding text 2: Funding: This research was funded by GeoCenter Denmark, grant number 6-2015.
PY - 2019
Y1 - 2019
N2 - The general perception has long been that lake eutrophication is driven by anthropogenic sources of phosphorus (P) and that P is immobile in the subsurface and in aquifers. Combined investigation of the current water and P budgets of a 70 ha lake (Nørresø, Fyn, Denmark) in a clayey till-dominated landscape and of the lake's Holocene trophic history demonstrates a potential significance of geogenic (natural) groundwater-borne P. Nørresø receives water from nine streams, a groundwater-fed spring located on a small island, and precipitation. The lake loses water by evaporation and via a single outlet. Monthly measurements of stream, spring, and outlet discharge, and of tracers in the form of temperature, δ18O and δ2H of water, and water chemistry were conducted. The tracers indicated that the lake receives groundwater from an underlying regional confined glaciofluvial sand aquifer via the spring and one of the streams. In addition, the lake receives a direct groundwater input (estimated as the water balance residual) via the lake bed, as supported by the artesian conditions of underlying strata observed in piezometers installed along the lake shore and in wells tapping the regional confined aquifer. The groundwater in the regional confined aquifer was anoxic, ferrous, and contained 4-5 μmol/L dissolved inorganic orthophosphate (DIP). Altogether, the data indicated that groundwater contributes from 64% of the water-borne external DIP loading to the lake, and up to 90% if the DIP concentration of the spring, as representative for the average DIP of the regional confined aquifer, is assigned to the estimated groundwater input. In support, paleolimnological data retrieved from sediment cores indicated that Nørresø was never P-poor, even before the introduction of agriculture at 6000 years before present. Accordingly, groundwater-borne geogenic phosphorus can have an important influence on the trophic state of recipient surface water ecosystems, and groundwater-borne P can be a potentially important component of the terrestrial P cycle.
AB - The general perception has long been that lake eutrophication is driven by anthropogenic sources of phosphorus (P) and that P is immobile in the subsurface and in aquifers. Combined investigation of the current water and P budgets of a 70 ha lake (Nørresø, Fyn, Denmark) in a clayey till-dominated landscape and of the lake's Holocene trophic history demonstrates a potential significance of geogenic (natural) groundwater-borne P. Nørresø receives water from nine streams, a groundwater-fed spring located on a small island, and precipitation. The lake loses water by evaporation and via a single outlet. Monthly measurements of stream, spring, and outlet discharge, and of tracers in the form of temperature, δ18O and δ2H of water, and water chemistry were conducted. The tracers indicated that the lake receives groundwater from an underlying regional confined glaciofluvial sand aquifer via the spring and one of the streams. In addition, the lake receives a direct groundwater input (estimated as the water balance residual) via the lake bed, as supported by the artesian conditions of underlying strata observed in piezometers installed along the lake shore and in wells tapping the regional confined aquifer. The groundwater in the regional confined aquifer was anoxic, ferrous, and contained 4-5 μmol/L dissolved inorganic orthophosphate (DIP). Altogether, the data indicated that groundwater contributes from 64% of the water-borne external DIP loading to the lake, and up to 90% if the DIP concentration of the spring, as representative for the average DIP of the regional confined aquifer, is assigned to the estimated groundwater input. In support, paleolimnological data retrieved from sediment cores indicated that Nørresø was never P-poor, even before the introduction of agriculture at 6000 years before present. Accordingly, groundwater-borne geogenic phosphorus can have an important influence on the trophic state of recipient surface water ecosystems, and groundwater-borne P can be a potentially important component of the terrestrial P cycle.
KW - Dissolved inorganic orthophosphate
KW - Eutrophication
KW - Geogenic phosphorus
KW - Groundwater-surface water interaction
KW - Transport
U2 - 10.3390/w11112213
DO - 10.3390/w11112213
M3 - Article
SN - 2073-4441
VL - 11
JO - Water (Switzerland)
JF - Water (Switzerland)
IS - 11
ER -