W.M. Stigliani

Changes in valued "Capacities" of soils and sediments as indicators of nonlinear and time-delayed environmental effects

This paper discusses the buffering, oxygen-donating, and sorption capacities of soils and sediments as an inter-connected system for regulating the retention and release of chemical pollutants. In this context, the author discusses the chemical conditions under which sediments may serve as a source or a sink for toxic materials, and conditions under which soils may retain or release them. It is demonstrated that nonlinear, time-delayed ecological transformations in soils and sediments often can be understood in terms of the interlinked system. The author discusses some possible future long-term environmental problems that might beset Europe, and some implications for a monitoring strategy for foresseing such problems.Because the release of adsorbed toxic chemicals from heavily polluted sediments and soils can occur suddenly owing to changes in oxygen status (i.e., redox potential) or acidity, strategies for preventing the long-term release of such materials should not only consider current conditions of pH and redox potential, but also, how those conditions might change in the future.

Soil sensitivity due to acid and heavy metal deposition in East Central Europe

Simultaneous soil acidification and deposition of heavy metals is a major concern for forest and agricultural soils of the Black Triangle region of East Central Europe including southern former East Germany, northern Bohemia of the Czech Republic, and southern Poland. The objective of this project was to develop historical and future projections of acid and heavy metal deposition to soils (As, Cd, Pb, Zn) and to produce a preliminary map of soil sensitivity to cadmium pollution and uptake by crops. Ultimately, we wish to assess the relative hazard and recovery times of soils to metals deposition in the region. Emission and deposition data bases obtained from several models developed at IIASA were linked using the Geographical Information System ARC/INFO to produce soil maps of sensitivity to cadmium mobility based on metals deposition, soil type, soil texture, organic matter content, and acid deposition. RAINS 6.1 (Alcamo et al., 1990) was utilized to produce maps of acid deposition for EMEP grids (150 km x 150 km). The largest amount of acid load is deposited in southern East Germany. Sulfur deposition in that area was 10–12 gS/m2/yr in 1990, and S+N deposition exceeded 8000 eq/ha/yr. But the “hot spot” for metals deposition is further to the east, in the Silesia area of southern Poland. The TRACE2 trajectory model of Alcamo, Bartnicki, and Olendrzynski (1992) was used to estimate cumulative metals deposition since 1955 with scenarios to 2010. Pb has improved over Europe since 1970 when depositions in the Ruhr River Valley of West Germany exceeded 60 mg/m2/yr. But cadmium deposition in southern Poland (Katowice and Krakow) has now accumulated to 60–70 mg/m2 by atmospheric deposition alone. During base case simulations from 1955–87, approximately 1.8 mg/kg Pb and 0.12 mg/kg Cd have been added to the mixed plow-layer of ∼30 cm. If these emissions continue indefinitely, the accumulation of metals will become problematic for agriculture and the food chain.

Summary of the workshop on delayed effects of chemicals in soils and sediments (Chemical Time Bombs), with emphasis on the Scandinavian region

Abstract The expression Chemical Time Bombs refers to a chain of events resulting in the delayed and sudden occurrence of harmful environmental effects due to the mobilization of chemicals stored in soils and sediments in response to slow alterations in environmental conditions. This workshop was part of a series of workshops in which basic ideas were developed and regional awareness promoted. The International Workshop on Delayed Environmental Effects of Chemical Pollution with Focus on the Nordic Countries was held in Uppsala, Sweden on 14 and 15 September 1991. A brief account of the discussions and the main conclusions are presented here. It was concluded that the effects in Nordic countries could be extended to areas with similar climate and bedrock conditions. These include the northern parts of Canada and Russia, Scotland, Iceland and Greenland. Fundamentally, Chemical Time Bombs in the Nordic and other cold climate areas do not differ from those in warmer areas. Conditions specific to cold climate areas are generally a thin soil cover, extensive occurrence of peat, and prolonged periods of frost and snow cover. Processes determining the buildup and triggering of Chemical Time Bombs differ only in rate and intensity as far as they are dependent on temperature and daylight. Loads of contaminants identified as being specific to Scandinavia are Hg and potentially toxic organic outputs of papers mills which threaten inland water ecosystems, as well as the Gulf of Bothnia and the Baltic Sea ecosystems. Assessment of risks from Chemical Time Bombs is still in its infancy. Quantitative risk assessment models for the accumulation in soils and sediments of heavy metals and toxic organic pollutants are still lacking.

Chemical emissions from the processing and use of materials: The need for an integrated emissions accounting system

This paper explores the need for a comprehensive emissions accounting system for environmentally harmful chemicals. Such a system requires the availability of economic statistics as a necessary complement to environmental data. A classification scheme is suggested that identifies environmental emissions at particular stages in the life cycle of chemicals as they flow through the industrial economy. Emissions are categorized as point- source emissions related to energy and industrial production, diffuse-source emissions from agricultural production, and consumption-related emissions. The latter are subdivided into emissions occuring during use of the product (dissipative emissions), and emissions occuring after disposal. The results of recent analyses are presented which suggest that in advanced industrial societies consumption-related and diffuse-source emissions are becoming increasingly important sources of chemical pollution relative to point-source emissions. Such sources are more difficult to regulate than are point sources, and our information base for identifying and quantifying the emissions is largely lacking. What is required is a more thorough understanding of the way our industrial system works with respect to chemical pollution. Studies in ‘industrial metabolism’ are recommended as a first step in seeking this understanding. Such studies should be complemented by strategies for reducing consumption- related emissions, a major component of which is emphasis on environmentally safe design of consumer products.

Long-Term Atmospheric Transport and Deposition of Heavy Metals in Central Europe

The so-called “Black Triangle” (BT) region covers the southern part of the former German Democratic Republic, south-western Poland and the northern part of Bohemia (Czech Republic). The BT, together with the heavily industrialized Upper Silesia region in southern Poland (BTUS), is the most polluted part of Europe, mainly due to acidic compounds and heavy metals. Continuous accumulations of cadmium, lead and zinc in soils may eventually lead to serious environmental consequences. Triggered by increased soil acidification, heavy metals may become mobilized, thus leading to plant and ground water contamination (the so-called “Chemical Time Bomb”). Acid deposition in the BTUS region has been continuously monitored in the framework of the EMEP program. However, up to now, not much is known about cumulative atmospheric deposition of heavy metals. In this study, we calculated long-term atmospheric deposition of Cd and Pb to the BTUS region (and to entire Europe) during the 1955–1987 period.

The Integral River Basin Approach to Assess the Impact of Multiple Contamination Sources Exemplified by the River Rhine

The basic premise of this paper is that solutions to problems of chemical pollution cannot be achieved unless an integrated assessment exists that connects flows of toxic materials through the industrial economy with their flows to the environment. As shown in Figure 1, flows through the industrial economy include all of the anthropogenic movements of materials through society. These include extraction of raw materials, processing them into consumer products, transporting the products to consumers who use and dispose of them, or in some cases recycle them. Ultimately, though, most of the materials that fuel and nourish industrial societies are returned in a degraded form to the land, the atmosphere, or to aqueous systems. The schematic diagram depicted in Figure 1 greatly simplifies the cycling of most materials in the industrial economy. Indeed, it is important to note that the anthropogenic cycling of chemicals can be just as complex as the cycling through the environment.