Exposure assessment at a PCDD/F contaminated site in Sweden—field measurements of exposure media and blood serum analysis

Background, aim, and scope  

The main pathway for human exposure to the highly toxic polychlorinated-p-dioxins and polychlorinated furans [polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)] is via dietary intake. Other exposure pathways may, however, be important in close proximity to point sources, such as wood preservation sites, where PCDD/F contaminated chlorophenols (CP) were previously used. In this study, a heavily PCDD/F contaminated CP saw mill site in Sweden was investigated. Human exposure through a broad spectrum of exposure pathways was assessed. Such studies are in demand since the question whether contaminated sites represent a current or future risk can only be answered by detailed site-specific risk assessments.     

Modelling Dissolved Organic Carbon Turnover in Humic Lake Örträsket, Sweden

The organic carbon balance of a lake with high input of allochthonous organic carbon is modelled integrating physical, chemical and biological processes. The physical model captures the behaviour of real thermal stratification in the lake for different flow situations during the period 1993–1997. The dissolved organic carbon model is based on simulated trajectories of water parcels. By tracking parcels, account is kept of environmental factors such as temperature and radiation as well as DOC quality for each parcel. The DOC concentration shows seasonal variations primarily dependent on inflow. The organic matter degradation (bacterial- and photodegradation) in the lake amounts to 1.5–2.5 mg C l^–1 yr^–1, where photooxidation is responsible for approximately 10%. The estimated DIC production in the lake is large compared to sediment mineralisation and primary production. The main conclusion is that the model with the selected parameterisations of the degradation processes reasonably well describes the DOC dynamics in a forest lake.     

Recovery of Soil Water,Groundwater, and Streamwater From Acidification at the Swedish Integrated Monitoring Catchments

Recovery from anthropogenic acidification in streams and lakes is well documented across the northern hemisphere. In this study, we use 1996–2009 data from the four Swedish Integrated Monitoring catchments to evaluate how the declining sulfur deposition has affected sulfate, pH, acid neutralizing capacity, ionic strength, aluminum, and dissolved organic carbon in soil water, groundwater and runoff. Differences in recovery rates between catchments, between recharge and discharge areas and between soil water and groundwater are assessed. At the IM sites, atmospheric deposition is the main human impact. The chemical trends were weakly correlated to the sulfur deposition decline. Other factors, such as marine influence and catchment features, seem to be as important. Except for pH and DOC, soil water and groundwater showed similar trends. Discharge areas acted as buffers, dampening the trends in streamwater. Further monitoring and modeling of these hydraulically active sites should be encouraged.     

Dioxin- and POP-contaminated sites—contemporary and future relevance and challenges

BACKGROUND, AIM AND SCOPE: Once they have been generated, polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and other persistent organic pollutants (POPs) can persist in soils and sediments and in waste repositories for periods extending from decades to centuries. In 1994, the US EPA concluded that contaminated sites and other reservoirs are likely to become the major source of contemporary pollution problems with these substances. With this in mind, this article is the first in a new series in ESPR under the title 'Case Studies on Dioxin and POP Contaminated Sites--Contemporary and Future Relevance and Challenges', which will address this important issue. The series will document various experiences from sites contaminated with PCDD/F and other POPs. This article provides an overview of the content of the articles comprising the series. In addition, it provides a review of the subject in its own right and identifies the key issues arising from dioxin/POP-contaminated sites. Additionally, it highlights the important conclusions that can be drawn from these examples. The key aim of this article and of the series as a whole is to provide a comprehensive overview of the types of PCDD/F contaminated sites that exist as a result of historical activities. It details the various processes whereby these sites became contaminated and attempts to evaluate their contemporary relevance as sources of PCDD/Fs and other POPs. It also details the various strategies used to assess these historical legacies of contamination and the concepts developed, or which are under development, to effect their remediation. MAIN FEATURES: Special sessions on 'Contaminated sites--Cases, remediation, risk and policy' were held at the DIOXIN conferences in 2006 and 2007, and this theme will be continued at DIOXIN 2008 to be held in Birmingham. Selected cases from the approximately 70 contributions made to these sessions, together with some additional invited case studies are outlined together with the key issues they raise. By evaluating these cases and adding details of experiences published in the current literature, an overview will be given of the different features and challenges of dioxin and POP-contaminated sites. RESULTS: This article provides a systematic categorisation of types of PCDD/F and POP-contaminated sites. These are categorised according to the chemical or manufacturing process, which generated the PCDD/Fs or POPs and also includes the use and disposal aspects of the product life cycle in question. The highest historical PCDD/F and dioxin-like polychlorinated biphenyl (PCB) contamination burdens have arisen as a result of the production of chlorine and of chlorinated organic chemicals. In particular, the production of chlorinated pesticides, PCBs and the related contaminated waste streams are identified being responsible for historical releases of toxic equivalents (TEQs) at a scale of many tonnes. Along with such releases, major PCDD/F contaminated sites have been created through the application or improper disposal of contaminated pesticides, PCBs and other organochlorine chemicals, as well through the recycling of wastes and their attempted destruction. In some extreme examples, PCDD/F contaminated sites have also resulted from thermal processes such as waste incinerators, secondary metal industries or from the recycling or deposition of specific waste (e.g. electronic waste or car shredder wastes), which often contain chlorinated or brominated organic chemicals. The examples of PCDD/F and dioxin-like PCB contamination of fish in European rivers or the impact of contaminated sites upon fishing grounds and upon other food resources demonstrate the relevance of these historical problems to current and future human generations. Many of the recent food contamination problems that have emerged in Europe and elsewhere demonstrate how PCDD/F and dioxin like PCBs from historical sources can directly contaminate human and animal feedstuffs and indeed highlight their considerable contemporary relevance in this respect. Accordingly, some key experiences and lessons learnt regarding the production, use, disposal and remediation of POPs from the contaminated sites are summarised. DISCUSSION: An important criterion for evaluating the significance and risks of PCDD/Fs and other POPs at contaminated sites is their present or future potential for mobility. This, in turn, determines to a large degree their propensity for off-site transport and environmental accessibility. The detailed evaluation of contaminated site cases reveals different site-specific factors, which influence the varied pathways through which poor water-soluble POPs can be mobilised. Co-contaminants with greater water solubility are also typically present at such sites. Hence, pumping of groundwater (pump and treat) is often required in addition to attempting to physically secure a site. At an increasing number of contaminated sites, securing measures are failing after relatively short time spans compared to the time horizon, which applies to persistent organic pollutant contamination. Due to the immense costs and challenges associated with remediation of contaminated sites 'monitored natural attenuation' is increasingly gaining purchase as a conceptual remediation approach. However, these concepts may well prove limited in their practical application to contaminated sites containing persistent organic pollutants and other key pollutants like heavy metals. CONCLUSIONS: It is inevitable, therefore, that dioxin/POP-contaminated sites will remain of contemporary and future relevance. They will continue to represent an environmental issue for future generations to address. The securing and/or remediation of dioxin/POP-contaminated sites is very costly, generally in the order of tens or hundreds of millions of dollars. Secured landfills and secured production sites need to be considered as constructions not made for 'eternity' but built for a finite time scale. Accordingly, they will need to be controlled, supervised and potentially repaired/renewed. Furthermore, the leachates and groundwater impacted by these sites will require ongoing monitoring and potential further remediation. These activities result in high maintenance costs, which are accrued for decades or centuries and should, therefore, be compared to the fully sustainable option of complete remediation. The contaminated site case studies highlight that, while extensive policies and established funds for remediation exist in most of the industrialised western countries, even these relatively well-regulated and wealthy countries face significant challenges in the implementation of a remediation strategy. This highlights the fact that ultimately only the prevention of contaminated sites represents a sustainable solution for the future and that the Polluter Pays Principle needs to be applied in a comprehensive way to current problems and those which may emerge in the future. RECOMMENDATIONS AND PERSPECTIVES: With the continuing shift of industrial activities in developing and transition economies, which often have poor regulation (and weak self-regulation of industries), additional global challenges regarding POPs and other contaminated sites may be expected. In this respect, a comprehensive application of the "polluter pays principle" in these countries will also be a key to facilitate the clean-up of contaminated areas and the prevention of future contaminated sites. The threats and challenges of contaminated sites and the high costs of securing/remediating the problems highlight the need for a comprehensive approach based upon integrated pollution prevention and control. If applied to all polluting (and potentially polluting) industrial sectors around the globe, such an approach will prove to be both the cheapest and most sustainable way to underpin the development of industries in developing and transition economies.     

Male preference for large females and assortative mating for body size in the sand lizard (Lacerta agilis)

Summary Male sand lizards (Lacerta agilis) are polygynous and guard individual females for several hours to days after copulation. Even though the copulation itself only lasts 2–4 min, the total time that a male invests per female is considerably more and may constitute a substantial investment during a mating season. In such situations, when male copulation frequency is constrained, or when variation in female fecundity is high, mate choice by males may be adaptive. Large body size in female sand lizards is correlated with higher fecundity. In choice experiments performed in the laboratory, male sand lizards preferred to court large females rather than small females. In addition, when there was little difference in size between the females in the experiment, the males visited the two females more often before they started to court the preferred female. The results from a field study during 1984 and 1987–1990 showed that females are non-aggressive, have small neighboring home ranges (c. 100 m²) and may share burrows and sites for thermoregulation. This means that females can be found close together and thus gives males the opportunity to choose a mate. Assortative mating with respect to size was observed in a natural population, as well as a limited number of direct choices of females by males. These results support the results of the choice experiment.     

The internal barriers of rotation for the 209 polychlorinated biphenyls

The internal barrier of rotation (Erot) was calculated for all 209 polychlorinated biphenyls (PCBs) by using a semi-empirical method, viz. the Austin Model 1 (AMI) Hamiltonian. The difference in total energy between a forced planar state and an optimised twisted structure was defined as Erot. The Erot values were in the range of 8.33 to 483 kj/mol, and were significantly influenced by the number of chlorine atoms inortho position. An additional structural characteristic of the PCBs influencing Erot ofortho substituted congeners was substitution by chlorine atoms in vicinalmeta positions, which is assumed to prevent outward bending ofortho substituents. This so-called buttressing effect contributed with 4 to 31 kj/mol per added chlorine atom. In conclusion, the internal barrier of rotation, calculated for all 209 PCBs, provides an important structure dependent physico-chemical parameter for multivariate modelling of future quantitative structure-activity and structure-property relationships (QSARs/QSPRs).