Intensive cultivation of fen peat soils (Eutric Histosols) for agricultural purposes, started in Europe about 250 years ago, resulting in decreased soil fertility, increased oxidation of peat and corresponding CO₂-emissions to the atmosphere, nutrient transfer to aquatic ecosystems and losses in the total area of the former native wetlands. To prevent these negative environmental effects set-aside programs and rewetting measures were promoted in recent years. Literature results and practical experiences showed that large scale rewetting of intensively used agricultural Histosols may result in the mobilisation of phosphorus (P), its transport to adjacent surface waters and an accelerated eutrophication risk. The paper summarises results from an international European Community sponsored research project and demonstrates how results obtained at different scales and from different scientific disciplines were compiled to derive a strategy to carry out rewetting measures. A decision support system (DSS) for a hydrologically sensitive area in the Droemling catchment in north-eastern Germany was developed and is presented as a tool to regulate rewetting in order to control P release. It is demonstrated that additional laboratory experiments to identify essential processes of P release during rewetting and the site-specific management of the water table, the involvement of specific knowledge and experience of the stakeholders are necessary to develop an applicable DSS. The presented DSS is practically used to prevent freshwater resources from diffuse P pollution.

Intensive cultivation of fen peat soils (Eutric Histosols) for agricultural purposes, started in Europe about 250 years ago, resulting in decreased soil fertility, increased oxidation of peat and corresponding CO2-emissions to the atmosphere, nutrient transfer to aquatic ecosystems and losses in the total area of the former native wetlands. To prevent these negative environmental effects set-aside programs and rewetting measures were promoted in recent years. Literature results and practical experiences showed that large scale rewetting of intensively used agricultural Histosols may result in the mobilisation of phosphorus (P), its transport to adjacent surface waters and an accelerated eutrophication risk. The paper summarises results from an international European Community sponsored research project and demonstrates how results obtained at different scales and from different scientific disciplines were compiled to derive a strategy to carry out rewetting measures. A decision support system (DSS) for a hydrologically sensitive area in the Droemling catchment in north-eastern Germany was developed and is presented as a tool to regulate rewetting in order to control P release. It is demonstrated that additional laboratory experiments to identify essential processes of P release during rewetting and the site-specific management of the water table, the involvement of specific knowledge and experience of the stakeholders are necessary to develop an applicable DSS. The presented DSS is practically used to prevent freshwater resources from diffuse P pollution.

The contamination of 27 urban topsoils has been assessed around two lead and zinc smelters (Metaleurop Nord and Umicore) in the North of France. Eighteen trace elements have been analysed (Ag, As, Bi, Cd, Co, Cr, Cu, Hg, In, Ni, Pb, Sb, Se, Sn, Tl, Th, U and Zn). The investigation included the study of the vertical distribution of Cd, Pb and Zn as indicators of pollution. It was shown that Cd, In, Pb, Sb and Zn were major pollutants followed in lesser quantities by Ag, Bi, Cu and Hg. In addition, As, Ni, Se, Sn and Tl were present at levels slightly higher than regional agricultural values. The other elements (Co, Cr, Th and U) were at endogenous levels. The observations have highlighted the strong heterogeneity of the physico-chemical parameters of urban soils and the existence of heavy contamination of the under layers by Cd, Pb and Zn. A potential transfer of metals from the topsoil to the deeper layers and especially Cd and Zn, is not excluded. Indeed the soil rework is not the only factor explaining contamination level of the deeper layers of the studied soils. The comparison of the studied element concentrations in urban soils with nearby local agricultural values shows that the dust emission originating from the Metaleurop and Umicore smelters were not the only source of contamination. Thus a large contamination of the studied urban soils by Sb and In could be explained by domestic combustion of coal for heating.

Water Air Soil Poll 252WD Times Cited:37 Cited References Count:36 | International audience | The contamination of 27 urban topsoils has been assessed around two lead and zinc smelters (Metaleurop Nord and Umicore) in the North of France. Eighteen trace elements have been analysed (Ag, As, Bi, Cd, Co, Cr, Cu, Hg, In, Ni, Pb, Sb, Se, Sn, Tl, Th, U and Zn). The investigation included the study of the vertical distribution of Cd, Pb and Zn as indicators of pollution. It was shown that Cd, In, Pb, Sb and Zn were major pollutants followed in lesser quantities by Ag, Bi, Cu and Hg. In addition, As, Ni, Se, Sn and Tl were present at levels slightly higher than regional agricultural values. The other elements (Co, Cr, Th and U) were at endogenous levels. The observations have highlighted the strong heterogeneity of the physico-chemical parameters of urban soils and the existence of heavy contamination of the under layers by Cd, Pb and Zn. A potential transfer of metals from the topsoil to the deeper layers and especially Cd and Zn, is not excluded. Indeed the soil rework is not the only factor explaining contamination level of the deeper layers of the studied soils. The comparison of the studied element concentrations in urban soils with nearby local agricultural values shows that the dust emission originating from the Metaleurop and Umicore smelters were not the only source of contamination. Thus a large contamination of the studied urban soils by Sb and In could be explained by domestic combustion of coal for heating.

The use of three inorganic materials as potential immobilizers of metals in soils has been studied by monitoring metal availability by EDTA extraction, the Simple Bioaccessibility Extraction Test (SBET) and extraction with a mixture of organic acids (OA). The SBET test was the most suitable for risk assessment in soils of recreational areas. The materials were a 4A-type zeolite, tri-calcium phosphate and 'slovakite', a synthetic sorbent developed for remediation of metal-polluted soils. Adsorption/desorption experiments of metals by the isolated materials showed that all materials caused a strong retention of metals from solutions, with negligible release by dilution. When added to soils of three parks, zeolite and, to a much lesser extent, slovakite caused some increase in soil pH. Despite this increase of pH, zeolite is often the least effective amendment for decreasing metal availability estimated by any method, and even sometimes seems to cause some increase, as well as an increase of soil electrical conductivity. In contrast, slovakite causes a decrease of available metals as estimated by EDTA and SBET, but by SBET the effect seems to be steadily reduced after the first samplings, so that after 300 days the metals extracted by this method are very similar to the data for the blanks. Despite the differences in pseudo-total metal contents, few differences are noticeable among parks. In general, these amendments are scarcely efficient in the case of neutral urban soils like those studied here. Other techniques are needed for controlling and, eventually, decreasing metal pollution hazard in soils of recreational areas.

The use of three inorganic materials as potential immobilizers of metals in soils has been studied by monitoring metal availability by EDTA extraction, the Simple Bioaccessibility Extraction Test (SBET) and extraction with a mixture of organic acids (OA). The SBET test was the most suitable for risk assessment in soils of recreational areas. The materials were a 4A-type zeolite, tri-calcium phosphate and ‘slovakite’, a synthetic sorbent developed for remediation of metal-polluted soils. Adsorption/desorption experiments of metals by the isolated materials showed that all materials caused a strong retention of metals from solutions, with negligible release by dilution. When added to soils of three parks, zeolite and, to a much lesser extent, slovakite caused some increase in soil pH. Despite this increase of pH, zeolite is often the least effective amendment for decreasing metal availability estimated by any method, and even sometimes seems to cause some increase, as well as an increase of soil electrical conductivity. In contrast, slovakite causes a decrease of available metals as estimated by EDTA and SBET, but by SBET the effect seems to be steadily reduced after the first samplings, so that after 300 days the metals extracted by this method are very similar to the data for the blanks. Despite the differences in pseudo-total metal contents, few differences are noticeable among parks. In general, these amendments are scarcely efficient in the case of neutral urban soils like those studied here. Other techniques are needed for controlling and, eventually, decreasing metal pollution hazard in soils of recreational areas. | Financial help of the Ministerio de Educación y Ciencia of Spain under project no. CTM2005–02256. | Peer reviewed