Modelling point and diffuse heavy metal emissions and loads in the Elbe basin

Abstract

Abstract:The reduction of pollutant loads in rivers requires a good comprehension of the contribution of all major (point and diffuse) sources in each sub-basin. Due to the sudden change of a centrally planned economy to a free-market economy in 1989, the River Elbe is one of the fastest changing transboundary river basins in Central Europe. The quantification of fluxes of heavy metals in the Elbe basin requires information on the spatial and temporal characteristics of emissions and on physical boundary conditions of the entire river basin. In this paper, a GIS-based model METALPOL will be presented, that describes the load of five heavy metals (Cd, Cu, Hg, Pb, Zn) in the Elbe basin over the period 1985-1999 as a function of (1) emissions from point and diffuse sources, (2) runoff, (3) soil types, (4) land use and (5) hydrogeology. The results from the model were validated with the measured heavy metal loads and showed reasonable agreement. Between 64% (for Hg) and 84% (for Pb) of the total heavy metal emissions in the Elbe basin is supplied by inputs from diffuse sources. The diffuse hydrological pathways with the highest share are erosion and urban areas. In most cases the measured heavy metal load is lower than the sum of the heavy metal emissions. Retention processes (e.g. sedimentation) largely explain this behaviour and are found to be dependent on the specific runoff of a catchment. About 81-97% of variance for the different heavy metals can be explained by the dependency on specific runoff. The uncertainty analysis presented in this paper has also illustrated that the reliability of the model simulations is directly affected by the quality of the input data (especially point source and urban emissions) and the distribution of the input data like rainfall data, emission data, soil data and land cover data. Finally, scenario analysis indicated that the current proposed measures are not stringent enough to achieve large reductions in heavy metal loads in the Elbe basin.

Modeling Management and Climate Change Impacts on Water Pollution by Heavy Metals in the Nizhnekamskoe Reservoir Watershed

“…A significant proportion of metals washed out from the catchment area accumulate with sediments in the river bottom: On average, ~46% copper, 62% zinc, and 30% manganese. These estimates are in good agreement with the results of HM retention in the Elbe River systems obtained using the METALPOL model [23]: For copper, on average, 51% with a range of variation from 35 to 60% for different tributaries; and for zinc, on average, 45% with a range of variation from 30 to 54%.…”

“…Among others, the Soil and Water Assessment Tool (SWAT) is widely used for the simulation of river discharge and pollution loads at different scales: From the continental scale [17], through the regional scale [18], to the scale of individual river catchments [19,20]. There is evidence in using semi-distributed models for the evaluation of measures to reduce contaminant loads and improve the ecological status of water bodies in Germany (SWIM, Soil and Water Integrated Model [21]; MONERIS, Modeling Nutrient Emissions in River Systems [22]; METALPOL model [23]) and in Sweden (HYPE, Hydrological Predictions for the Environment [24]) in the framework of the implementation of the European Water Framework Directive. In semi-distributed models, the watershed is divided into several subbasins-Hydrological Response Units (HRUs).…”

Modelling the overland transport of lead deposited from the atmosphere in the elbe catchment over four decades (1958–1995)

“…The problem of estimating heavy-metal emissions via surface and subsurface runoff cannot be solved since there is no method available to measure these heavy-metal fluxes (see also Vink and Peters, 2003). For an accurate pollution survey by indirect diffuse sources in large river basins such as the Elbe, future research should focus on developing measurement and modelling techniques to determine overland fluxes on large scales.…”