TY - JOUR
T1 - Modelling assessment of regional groundwater contamination due to historic smelter emissions of heavy metals
AU - van der Grift, Bas
AU - Griffioen, Jasper
PY - 2008/2/1
Y1 - 2008/2/1
N2 - Historic emissions from ore smelters typically cause regional soil
contamination. We developed a modelling approach to assess the impact of
such contamination on groundwater and surface water load, coupling
unsaturated zone leaching modelling with 3D groundwater transport
modelling. Both historic and predictive modelling were performed, using
a mass balance approach for three different catchments in the vicinity
of three smelters. The catchments differ in their hydrology and
geochemistry. The historic modelling results indicate that leaching to
groundwater is spatially very heterogeneous due to variation in soil
characteristics, in particular soil pH. In the saturated zone, cadmium
is becoming strongly retarded due to strong sorption at neutral pH, even
though the reactivity of the sandy sediments is low. A comparison
between two datasets (from 1990 to 2002) on shallow groundwater and
modelled concentrations provided a useful verification on the level of
statistics of "homogeneous areas" (areas with comparable land use, soil
type and geohydrological situation) instead of comparison at individual
locations. While at individual locations observations and the model
varies up to two orders of magnitude, for homogeneous areas, medians and
ranges of measured concentrations and the model results are similar. A
sensitivity analysis on metal input loads, groundwater composition and
sediment geochemistry reveals that the best available information
scenario based on the median value of input parameters for the model
predicts the range in observed concentrations very well. However, the
model results are sensitive to the sediment contents of the reactive
components (organic matter, clay minerals and iron oxides). Uncertainty
in metal input loads and groundwater chemistry are of lesser importance.
Predictive modelling reveals a remarkable difference in geochemical and
hydrological controls on subsurface metal transport at catchment-scale.
Whether the surface water load will peak within a few decades or
continue to increase until after 2050 depends on the dominant land use
functions in the areas, their hydrology and geochemical build-up.
AB - Historic emissions from ore smelters typically cause regional soil
contamination. We developed a modelling approach to assess the impact of
such contamination on groundwater and surface water load, coupling
unsaturated zone leaching modelling with 3D groundwater transport
modelling. Both historic and predictive modelling were performed, using
a mass balance approach for three different catchments in the vicinity
of three smelters. The catchments differ in their hydrology and
geochemistry. The historic modelling results indicate that leaching to
groundwater is spatially very heterogeneous due to variation in soil
characteristics, in particular soil pH. In the saturated zone, cadmium
is becoming strongly retarded due to strong sorption at neutral pH, even
though the reactivity of the sandy sediments is low. A comparison
between two datasets (from 1990 to 2002) on shallow groundwater and
modelled concentrations provided a useful verification on the level of
statistics of "homogeneous areas" (areas with comparable land use, soil
type and geohydrological situation) instead of comparison at individual
locations. While at individual locations observations and the model
varies up to two orders of magnitude, for homogeneous areas, medians and
ranges of measured concentrations and the model results are similar. A
sensitivity analysis on metal input loads, groundwater composition and
sediment geochemistry reveals that the best available information
scenario based on the median value of input parameters for the model
predicts the range in observed concentrations very well. However, the
model results are sensitive to the sediment contents of the reactive
components (organic matter, clay minerals and iron oxides). Uncertainty
in metal input loads and groundwater chemistry are of lesser importance.
Predictive modelling reveals a remarkable difference in geochemical and
hydrological controls on subsurface metal transport at catchment-scale.
Whether the surface water load will peak within a few decades or
continue to increase until after 2050 depends on the dominant land use
functions in the areas, their hydrology and geochemical build-up.
U2 - 10.1016/j.jconhyd.2007.10.001
DO - 10.1016/j.jconhyd.2007.10.001
M3 - Article
SN - 0169-7722
VL - 96
SP - 48
EP - 68
JO - Journal of Contaminant Hydrology
JF - Journal of Contaminant Hydrology
IS - 1
ER -
