Bo Bergbäck

Impact of Atmospheric Long Range Transport of Lead, Mercury and Cadmium on the Swedish Forest Environment

Emissions of Hg, Pb, and Cd to air aretransported over wide areas in Europe and deposited far awayfrom their sources. About 80% of the atmospheric depositionof these metals in south Sweden originate from emissions inother countries. As a result of the increased anthropogenicdeposition the concentrations of Hg, Pb, and Cd in the morlayer of forest soils have increased considerably, mainlyduring the 20th century. Although the atmosphericdeposition of these elements has declined during the mostrecent decades, the reduction of the input of Hg and Pb isnot sufficient to prevent a further accumulation. Theconcentrations of Hg and Pb are still increasing by ca. 0.5and ca. 0.2% annually in the surface layer of forest soils.In contrast, the Cd concentration is currentlydecreasing in a large part of Sweden as a result of bothdeposition decreases and enhanced leaching induced by soilacidification. The accumulation factors of Hg and Pb,especially in the forest topsoils of south Sweden, arealready above those at which adverse effects on soilbiological processes and organisms have been demonstrated instudies of gradients from local emission sources andlaboratory assessment. There are also indications of sucheffects at the current regional concentrations of Hg and Pbin mor layers from south Sweden, judging from observationsin field and laboratory studies. There is an apparent riskof Pb induced reduction in microbial activity over parts ofsouth Sweden. This might cause increased accumulation oforganic matter and a reduced availability of soil nutrients.At current concentrations of Hg in Swedish forest soils,effects similar to those of Pb are likely. Increasedconcentrations of these elements in organs of mammals andbirds have also been measured, though decreases have beendemonstrated in recent years, related to changes inatmospheric deposition rates. As a result of current andpast deposition in south Sweden, concentrations of Hg infish have increased about fivefold during the 20thcentury. This implies risks for human health, when fish frominland waters are used for food. Although the concentrationof Hg in fish has decreased ca. 20% during the last decade,probably as a result of the reduced deposition, the levelstill exceeds the general limit (0.5 mg kg-1) in about half(ca. 40 000) of the Swedish lakes. In order to reduceconcentrations in fish to the level recommended, and avoidfurther accumulation of Hg in soils, the atmosphericdeposition has to be reduced to ca. 20% of the current deposition rate. This can only be achieved by international co-operation.

GOODS IN THE ANTHROPOSPHERE AS A METAL EMISSION SOURCE A Case Study of Stockholm, Sweden

The aim of this study was to quantify the diffuse emissionsduring use of metal containing goods in the capital of Sweden,Stockholm. The following metals were studied: Cadmium (Cd), Chromium (Cr), Copper (Cu), Lead (Pb), Mercury (Hg), Nickel (Ni) and Zinc (Zn).A major part of the metals are found in a protected environmentwhere degrading processes like corrosion are most limited. However, during the lifetime of some goods the metal release to the environment is significant. The quantitatively most dominant emissions were found for Cu and Zn. The tap water system and roofs/fronts (Cu) represent goods with large exposedareas but with relatively small release rates per unit. In contrast, brake linings, aerial lines and electrical grounding (Cu) and tyres, brake linings and chemicals (Zn) are allgoods with high release rates but mostly limited exposed stocks.High yearly emissions are also found for Pb, ammunition andsinkers dominate the calculated emissions totally. For Cr and Ni, stainless steel represent the major part of the stocks, butcorrosion was estimated to give only a minor contribution to the emissions. Potential emission sources, i.e. stabilisers,pigments and plated goods dominate the exposed Cd stock. Theseemissions were not quantified due to lack of data. Hg is currently phased out, but one major source of emission, i.e. the use of amalgam, will be continuously significant for several decades. The importance of the traffic sector is obvious. The emissionsfrom brake linings (Cu, Zn and Pb), tyres (Zn, Pb, Cr and Ni)and asphalt wear (Cu, Zn, Cr, Ni and Pb) are all of large importance for the total emission from respectively metal.

Century Perspective of Heavy Metal Use in Urban Areas. : A Case Study in Stockholm

The inflow and stock (amount in use) of heavy metals (cadmium(Cd), chromium (Cr), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni) and zinc (Zn)) in goods in 1995 have been quantifiedin the anthroposphere of Stockholm, Sweden. Statistics on national, regional and local level were used. Contacts were established with representatives from production and constructionin the industrial sector and with authorities. The results show that the stock of Cd is 0,2 kg per capita. For the other heavymetals the corresponding result per capita is: Cr 8, Cu 170, Hg 0,01, Ni 4, Pb 73 and Zn 40 kg. The inflow varies between2–8%of the stock indicating the importance of the stock. The lowestlevels are for Cu and Pb. Heavy metal levels in solid waste are high, between 15–45% of the amount in the inflow (Hg excluded), the lowest values were for Cu and Pb. Thus, recyclingis incomplete. Long life expectancy goods form the majority of the stock but there is a tendency that short life expectancy goods increase their importance in the inflow. Concealedgoods are also more frequent in inflow than in the stock.

Uncertain Numbers and Uncertainty in the Selection of Input Distributions—Consequences for a Probabilistic Risk Assessment of Contaminated Land

Risks from exposure to contaminated land are often assessed with the aid of mathematical models. The current probabilistic approach is a considerable improvement on previous deterministic risk assessment practices, in that it attempts to characterize uncertainty and variability. However, some inputs continue to be assigned as precise numbers, while others are characterized as precise probability distributions. Such precision is hard to justify, and we show in this article how rounding errors and distribution assumptions can affect an exposure assessment. The outcome of traditional deterministic point estimates and Monte Carlo simulations were compared to probability bounds analyses. Assigning all scalars as imprecise numbers (intervals prescribed by significant digits) added uncertainty to the deterministic point estimate of about one order of magnitude. Similarly, representing probability distributions as probability boxes added several orders of magnitude to the uncertainty of the probabilistic estimate. This indicates that the size of the uncertainty in such assessments is actually much greater than currently reported. The article suggests that full disclosure of the uncertainty may facilitate decision making in opening up a negotiation window. In the risk analysis process, it is also an ethical obligation to clarify the boundary between the scientific and social domains.

Accumulated Environmental Impact: The Case of Cadmium in Sweden

Abstract In this study, the total flows of cadmium in Sweden in the period 1940–1990 — based on trade statistics, the manufacture of goods and the persistence of products in the environment — have been calculated. The metal industry, the mining of zinc and lead ores and the manufacturing of phosphorus fertilizers have been the dominant sources of industrial cadmium emissions to the environment. The application of fertilizers has led to the depositing of significant amounts of cadmium on agricultural land. Consumption emissions have originated from the use of cadmium in various products, e.g. rechargeable nickel-cadmium batteries, pigments, stabilizers in polyvinyl-chloride plastics and protective plating for metals. The total calculated emissions of cadmium in Sweden, from production and consumption, have, in the past, been approximately 1700 t. The accumulated amount of cadmium used, including cadmium in alloys and as impurities in zinc, is approximately 5000 t. The ‘societal weathering rate’ exceeded the natural rate more than 4 times in 1970, and the present rate (1990) of anthropogenic emissions is still higher than the natural release due to weathering.

Mobility of trace elements in black shale assessed by leaching tests and sequential chemical extraction

ABSTRACT This study focuses on the abundance and mobility of Ca, Fe, S and trace elements (As, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, U, V and Zn) in black shale (alum shale) in SE Sweden. Samples of non-weathered, weathered and burnt black shale were chemically characterized and the potential element release from them was assessed by standard water-based leaching tests and pH/redox-regulated availability tests. Sequential chemical extractions provided further information on the phases in which the elements are bound. Results show that the shale is very rich in As (88–122 ppm), Cd (0.4–4.6 ppm), Mo (64–176 ppm), U (27–71 ppm) and V (496–1560 ppm). Cadmium and Mo, bound mainly in sulphides or organic matter, are very mobile in the non-burnt shale, with mobilization rates of up to 19% (190 μg/kg) and 25% (16 mg/kg), respectively, using only water as extraction medium. The non-weathered shale is also relatively rich in Cu (113 ppm), Ni (100 ppm) and Zn (304 ppm), the latter two in particular showing behaviour similar to that of Cd, but with lower mobilization rates. In all samples U and V are found mainly in weathering-resistant mineral phases and thus have a lower mobility, but due to the high abundance in the material, significant amounts of U can be released on longer time scales (up to 6 mg/kg, as indicated by the pH/redox-regulated test). Less than 1% of the As is released in all the leaching tests, indicating that upon oxidation it is retained in the solid phase. The overall conclusion is that this material has a high potential for releasing Cd, Mo, Ni, U and Zn during weathering.

Phasing out cadmium, lead and mercury : Effects on urban stocks and flows

Large stocks of metals have accumulated in the urban technosphere (i.e., the physical environment altered by human activity). To minimize health and environmental risks, attempts were begun in the 1980s to phase out the use of cadmium (Cd), lead (Pb), and mercury (Hg). To study the effect of this attempt, we conducted substance flow analyses (SFAs) in Stockholm, Sweden, in 1995 and in 20022003, which allow a comparison of the results over time. The SFAs showed a reduction in the stocks of Cd and Hg by approximately 25% to 30% between 1995 and 20022003. For Pb, the stock development was more uncertain. Cd and Hg inflow was substantially reduced during this period, but Pb inflow increased. Amounts of Cd and Pb in waste were still large, whereas Hg flows in waste were decreasing. Furthermore, although emissions of Pb decreased, Cd and Hg emissions were in the same range as in 1995. The application of SFAs has provided unique data on the accumulation of metals in the Stockholm technosphere, thus serving as a valuable indicator of how the phasing out progresses. The changes can be related to regulations, initiatives by industries and organizations, and the proactive attitude of the local environmental authorities and of the water company.

Heritage of Cadmium and Lead - A Case Study of a Swedish Accumulator Factory

Abstract In this study, cadmium and lead emissions from a Swedish point source (manufacture of nickel-cadmium accumulators and smelting of lead accumulators) have been calculated from local industrial statistics. Cadmium and lead concentrations present in soil were used to estimate the total load of these metals. Differences between both measured and calculated total amounts, together with soil metal concentration data from the early 1970s, give an opportunity to discuss the leaching rate for cadmium and lead in a soil profile. The downward transport of metals from the top soil has been going on for a minimum of 16 years (1974–1990) to 50 years (lead) or 80 years (cadmium). This gives a leaching rate for cadmium of 0.41–2.0% year −1 and for lead of 0.25–0.79% year −1 assuming a constant leaching process. Since the major part of the leaching has occurred during the last four decades (both cadmium and lead emissions were limited before 1950), the calculated leaching rates would be 0.8% year −1 (Cd) and 0.3% year −1 (Pb). Thus, there is an agreement in calculated cadmium rates with values reported in the literature but this study indicates a significantly higher leaching rate for lead.

Variability and uncertainty in Swedish exposure factors for use in quantitative exposure assessments.

Information of exposure factors used in quantitative risk assessments has previously been compiled and reported for U.S. and European populations. However, due to the advancement of science and knowledge, these reports are in continuous need of updating with new data. Equally important is the change over time of many exposure factors related to both physiological characteristics and human behavior. Body weight, skin surface, time use, and dietary habits are some of the most obvious examples covered here. A wealth of data is available from literature not primarily gathered for the purpose of risk assessment. Here we review a number of key exposure factors and compare these factors between northern Europe--here represented by Sweden--and the United States. Many previous compilations of exposure factor data focus on interindividual variability and variability between sexes and age groups, while uncertainty is mainly dealt with in a qualitative way. In this article variability is assessed along with uncertainty. As estimates of central tendency and interindividual variability, mean, standard deviation, skewness, kurtosis, and multiple percentiles were calculated, while uncertainty was characterized using 95% confidence intervals for these parameters. The presented statistics are appropriate for use in deterministic analyses using point estimates for each input parameter as well as in probabilistic assessments.

Sources of antimony in an urban area

Environmental context. The global production and use of antimony (Sb) increase together with stocks and emissions, but there are gaps in our knowledge concerning environmental effects. Here, a reconstruction of major Sb flows in an urban area was conducted. The major emission source of Sb identified was wear of brake linings, although other sources may also be of importance, e.g. diffuse emission of flame-retarded goods. Abstract. The present study sets out to analyse the urban metal sources of Sb, by estimating the stock of Sb in use, and to present related flows and emissions in Stockholm, Sweden, in 2005. Antimony was studied with the main methodology of substance flow analysis with existing data, while chemical analysis was used as a complement. No large point sources were found reported to the authorities; hence, the dominating source for Sb is diffuse and originates from goods. The total Sb stock in Stockholm in 2005 was ~430 000 kg (range 110 000–1 700 000 kg) and the total Sb inflow was estimated at 45 000 kg year–1 (range 30 000–67 000 kg). The stock was dominated by flame-retarded goods, cable shielding, glass and accumulators. The Sb emission was estimated at ~720 kg year–1 (range 430–1200 kg year–1). Despite large uncertainties and missing data, the results supported the notion of the importance of brake linings as a source of Sb emissions (710 kg year–1), whereas other goods such as textiles (4.5 kg year–1), tyres (1.4 kg year–1), sinkers, ammunition and polyethylene terephthalate (PET) bottles and packaging were minor sources. However, flame-retarded goods are still poorly quantified and are seen as a potential emission source.