Uncertainty of measurement or of mean value for the reliable classification of contaminated land

Classification of contaminated land is important for risk assessment and so it is vital to understand and quantify all of the uncertainties that are involved in the assessment of contaminated land. This paper uses a case study to compare two methods for assessing the uncertainty in site investigations (uncertainty of individual measurements, including that from sampling, and uncertainty of the mean value of all measurements within an area) and how the different methods affect the decisions made about a site. Using the ‘uncertainty of the mean value’ there is shown to be no significant possibility of ‘significant harm’ under UK guidance at one particular test site, but if you consider the ‘uncertainty of the measurements’ a significant proportion (50%) of the site is shown to be possibly contaminated. This raises doubts as to whether the current method using ‘uncertainty of the mean’ is sufficiently robust, and suggests that ‘uncertainty of measurement’ information may be preferable, or at least beneficial when used in conjunction.     

The Application of Risk Assessment to Contaminated Land: The British Gas Experience

British Gas owns over 900 sites within the UK with a total land area in excess of 5500 ha. Many of the sites are former gasworks, chemical works or associated holder stations.
Although serious attempts were made to remove contamination during the last three decades, the operating and demolition standards previously considered to be adequate may no longer be acceptable and may have given rise to sites with the potential to contaminate adjacent land, surface waters and ground-water. As a result, further actions may now be required on these sites to reach new environmental standards, thereby reducing any chance there may be of legal liability on the Company.
This paper describes the advantages and disadvantages of several qualitative and quantitative risk-assessment methods which can be used to prioritize potentially contaminated sites for further investigation. The use of site investigation data to accurately target risk reduction in site remediation proposals is also discussed.     

美国“超级基金”制度研究——探索污染土地修复中的用地规划协调途径

美国“超级基金”制度是一项由联邦政府主导的对全国污染最严重土地进行修复和治理的制度,它基于未来土地使用的用地规划协调机制,有效地将未来土地使用规划决策与地块环境治理过程整合起来,以此来协调污染土地修复过程中基于环境保护的生态环境效益和基于土地重新开发利用的经济和社会效益。本文分析了美国“超级基金”制度及其用地规划协调机制的缘起、建构和操作特点,并在此基础上探讨了其对于我国解决同类问题的借鉴意义。     

Sampling and pre-treatment--some observations from the United Kingdom

This paper arises from the current discussion in the United Kingdom to develop, under the auspices of the British Standards Institution a 'code of practice for investigation of potentially contaminated sites'. Within this code of practice a key element in the analysis is the sampling strategy for the collection of samples and characterisation of the site. The paper briefly summarises the current status of the development of the ideas on the sampling and pre-treatment of potentially contaminated sites, and emphasises the importance which must be attached to the sampling phase of any investigation if the outcomes are to be valid. A brief reference is made to other studies which have addressed the problem of sampling contaminated sites. These studies have considered both the design of the sampling scheme and the number of samples to be taken in relation to the costs of sampling, the nature of the potential hazard, the potential risks involved and the statistical requirements if samples are to be used to predict within given confidence limits.     

A new method to compare vehicle emissions measured by remote sensing and laboratory testing: high-emitters and potential implications for emission inventories

A new method is presented which is designed to investigate whether laboratory test data used in the development of vehicle emission models adequately reflects emission distributions, and in particular the influence of high-emitting vehicles. The method includes the computation of a ‘high-emitter’ or ‘emission distribution’ correction factor for use in emission inventories. In order to make a valid comparison we control for a number of factors such as vehicle technology, measurement technique and driving conditions and use a variable called ‘Pollution Index’ (g/kg). Our investigation into one vehicle class has shown that laboratory and remote sensing data are substantially different for CO, HC and NO_x emissions, both in terms of their distributions as well as in their mean and 99-percentile values. Given that the remote sensing data has larger mean values for these pollutants, the analysis suggests that high-emitting vehicles may not be adequately captured in the laboratory test data.The paper presents two different methods for the computation of weighted correction factors for use in emission inventories based on laboratory test data: one using mean values for six ‘power bins’ and one using multivariate regression functions. The computed correction factors are substantial leading to an increase for laboratory-based emission factors with a factor of 1.7-1.9 for CO, 1.3-1.6 for HC and 1.4-1.7 for NO_x (actual value depending on the method). However, it also clear that there are points that require further examination before these correction factors should be applied. One important step will be to include a comparison with other types of validation studies such as tunnel studies and near-road air quality assessments to examine if these correction factors are confirmed. If so, we would recommend using the correction factors in emission inventories for motor vehicles.     

Ecological risk assessment in legislation on contaminated soil in The Netherlands

Recently the Dutch soil policy was revised including new rules for the relocation of contaminated soil and dredged soil material. With these rules, new methods for ecotoxicological risk assessment were implemented. One of the new methods is the assessment of the local toxic pressure of mixtures, also known as the ms-PAF- method, based on the Species Sensitivity Distribution concept. The ms-PAF method is applied for risk assessment of spreading of dredged soil material on adjacent land. Its application will possibly be extended to the derivation of local soil quality standards relevant in the context of soil relocation. The application of the local toxic pressure will probably increase the reuse of contaminated soil and dredged soil material and hence will reduce the amounts considered to be unfit for use. With this method, local ecological risk limits are derived using pore water concentrations and effects on water organisms. Pore water concentrations are subsequently transferred to total soil concentrations using empirical relationships. The methodology does not impose upper limits for total soil concentrations. In soils with a high sorption capacity, total soil concentrations that are considered to be acceptable may be several times higher than the current Dutch intervention values. The possible introduction of the ms-PAF method will open the door to local soil relocation with soils containing large amounts of (semi-permanently soil bound) contaminants. Since the ms-PAF method is not yet properly validated, the lack of evidence of ecological effects using models like the ms-PAF method cannot be regarded as an indication for the absence of effects in reality. The Dutch soil quality decree would gain environmental ambition when the ms-PAF method was combined with a realistic upper limit on total soil concentrations. This would prevent contamination of land by means of soil relocation.     

Property rights,transaction costs and institutional change: Conceptual framework and literature review

For want of appropriate and effectual methodological approaches or analytical instruments, analysis of socio-economic phenomena can sometimes be problematic. As Frances et al. have aptly noted, any analysis of social nature begs the question: ‘with what theoretical tools do we approach the analysis of events and processes?’ (p. 1). In land matters, for example, Malpezzi (1999b,c) has keenly observed that most of the studies on land reforms have focused on the rural and agricultural sectors, at the expense of the urban sector. Arguably, the paucity of land policy/reform studies on the urban sector could be explained, to a large measure, by the fact that most of the studies carried out in this area apply theoretical frameworks or models that are highly abstract (e.g. neoclassical economic models) or too simplistic in approach.¹ Such models or methodological frameworks may not be readily applicable or efficacious in explaining the convoluted urban land market realities. The narrow option for alternative tools of analysis for studying land market ‘events and processes’ (to use Frances et al.’s (1991) terminology) may well have hindered land policy/reform research in the urban sector. Against that background, this paper advances an eclectic, property-rights-based approach that is robust and versatile enough to have wide application. An empirical study conducted under the framework attests to the relevance of such an approach to land use policy and urban land market analysis.     

Biological assessment of contaminated land using earthworm biomarkers in support of chemical analysis

Biological indicators can be used to assess polluted sites but their success depends on the availability of suitable assays. The aim of this study was to investigate the performance of two earthworm biomarkers, lysosomal membrane stability measured using the neutral red retention assay (NRR-T) and the total immune activity (TIA) assay, that have previously been established as responsive to chemical exposure. Responses of the two assays were measured following in situ exposure to complexly contaminated field soils at three industrial sites as well as urban and rural controls. The industrial sites were contaminated with a range of metal (cadmium, copper, lead, zinc, nickel and cobalt) and organic (including polycyclic aromatic hydrocarbons) contaminants, but at concentrations below the 'New Dutch List' Intervention concentrations. Exposed earthworms accumulated both metals and organic compounds at the contaminated sites, indicating that there was significant exposure. No effect on earthworm survival was found at any of the sites. Biomarker measurements, however, indicated significant effects, with lower NRR-T and TIA found in the contaminated soils when compared to the two controls. The results demonstrate that a comparison of soil pollutant concentrations with guideline values would not have unequivocally identified chemical exposure and toxic effect for soil organisms living in these soils. However, the earthworm biomarkers successfully identified significant exposure and biological effects caused by the mixture of chemicals present.     

Does remediation save lives? — On the cost of cleaning up arsenic-contaminated sites in Sweden

Sweden has only just begun remediation of its many contaminated sites, a process that will cost an estimated SEK 60,000 million (USD 9100 million). Although the risk assessment method, carried out by the Swedish EPA, is driven by health effects, it does not consider actual exposure. Instead, the sites are assessed based on divergence from guideline values. This paper uses an environmental medicine approach that takes exposure into account to analyse how cancer risks on and near arsenic-contaminated sites are implicitly valued in the remediation process. The results show that the level of ambition is high. At 23 contaminated sites, the cost per life saved varies from SEK 287 million to SEK 1,835,000 million, despite conservative calculations that in fact probably underestimate the costs. It is concluded that if environmental health risks are to be reduced, there are probably other areas where economic resources can be used more cost-effectively.     

Numerical simulation of the behaviors of test square for prehistoric earthen sites during archaeological excavation

During the process of archaeological excavation in the regions of Southeast China, collapse of test square usually occurs due to poor site-specific conditions. In this paper, the fast Lagrangian analysis of continua in three dimensions (FLAC3D) is employed to reveal the behaviors of test square. Taking the archaeological works in Liangzhu prehistoric earthen sites as the research background, the paper first introduces the geological setting, excavation procedure and monitoring scheme of the studied test square. Then, the deformation of four sides of the test square is modeled using FLAC3D. By comparison, it shows that the numerical results are consistent with the results from field monitoring. The result suggests that the numerical simulation can be effectively applied to representing the actual behaviors of the test square, which is helpful for determination of excavation scheme and stability evaluation of the test square during archaeological excavation.     

Contaminated Land and Aquifer Protection

The paper discusses the definition of contaminated land, its legislative controls, how it is identified and how a hazard ranking exercise may be carried out on a property portfolio in order to deal constructively with the problem of contaminated land. Such land is important because it can have substantial financial penalties attached to its investigation and remediation. The potential liabilities now arising from environmental impairment are such that anyone involved in the acquisition, ownership or disposal of land has to take an interest in it. The legislative background and environmental policy considerations which affect contaminated land are described, as well as the role of the National Rivers Authority in dealing with the subject. The principal types and sources of contaminated land are identified and current guidelines and standards for dealing with it are discussed. A technique developed for Scottish Enterprise whereby a property portfolio can be ranked in order of its potential hazard by combining the sensitivity of a site with its contamination potential in order to define environmental risk is described, and the necessity to seek professional and experienced advice in evaluating the consequences of contaminated land is highlighted.     

Introducing a method of human health risk evaluation for planning and soil quality management of heavy metal-polluted soils—An example from Grugliasco (Italy)

European governmental institutions, as well as local communities, have recently become aware of the threats arising from soil pollution for the welfare of the population. Humans contact with soils is more likely in urban than in rural areas, and is strongly dependent on land use. Spatial planning and land management may have important impacts on the potential transfer of pollutants from contaminated soils to humans. In the present study, we propose a land use-based method for the evaluation of human health risks arising from heavy metal-contaminated urban soils, addressing in particular the influence of planning measures and land use changes on such risks. The method accounts for the role of the bioavailability of soil metals as a key factor in health risk assessment. In order to increase method applicability, a step-by-step procedure and a calculation tool were elaborated. The method can be used to identify areas in which the current or planned land use is associated with unacceptable health risks and to optimise the allocation of a certain land use to areas that are well suited and where the risks are minimal. A risk index is calculated for the area, taking the land use into consideration, as the sum of the risks from different exposure pathways and different heavy metals. For those areas where risk is identified as unacceptable, alternative planning or management options should be defined to achieve a maximal risk reduction in a cost-effective way. The method is illustrated using the Italian municipality, Grugliasco.     

Generic Assessment Criteria for human health risk assessment of potentially contaminated land in China

Generic Assessment Criteria (GAC) are derived using widely applicable assumptions about the characteristics and behaviour of contaminant sources, pathways and receptors. GAC provide nationally consistent guidance, thereby saving money and time. Currently, there are no human health based Generic Assessment Criteria (GAC) for contaminated sites in China. Protection of human health is therefore difficult to ensure and demonstrate; and the lack of GAC makes it difficult to tell if there is potential significant risk to human health unless site-specific criteria are derived. This paper derived Chinese GAC (GAC) for five inorganic and eight organic substances for three regions in China for three land uses: urban residential without plant uptake, Chinese cultivated land, and commercial/industrial using the SNIFFER model. The SNIFFER model has been further implemented with a dermal absorption algorithm and the model default input values have been changed to reflect the Chinese exposure scenarios. It is envisaged that the modified SNIFFER model could be used to derive GAC for more contaminants, more Regions, and more land uses. Further research to enhance the reliability and acceptability of the GAC is needed in regional/national surveys in diet and working patterns.     

Developing decision support tools for the selection of “gentle” remediation approaches

A range of tools have been proposed to support decision making in contaminated land remediation. From a European perspective it is clear, however, that there are considerable national differences in the decision support process, and more generally in the extent to which this process supports the selection of less invasive, alternative remediation options such as phytoremediation, in situ immobilisation etc. (referred to here as “gentle” remediation technologies). In this paper we present results from the recently completed European Union ERANET SNOWMAN project SUMATECS (Sustainable Management of Trace Element Contaminated Sites), and critically review available decision support tools in terms of their fitness for purpose for the application of gentle remediation technologies. Stakeholder feedback indicates a lack of knowledge amongst stakeholders of currently available decision support tools. We propose that decision support which focuses on gentle remediation is more strongly incorporated into existing, well-established (national) decision support tools / decision-frameworks, to promote more widespread use and uptake.     

Integrated understanding of urban land, groundwater, baseflow and surface-water quality—The City of Birmingham, UK

Integrated understanding of urban land, groundwater (shallow and deep), baseflow and surface-water quality relationships is required for effective urban water-quality management. Chemical quality data from across these media have been collected for the Birmingham (UK) aquifer—River Tame conurbation to assess chemical transport from contaminated land to groundwater to baseflow to surface water. Although metals concentrations were high in soils, low leachability and attenuation caused concentrations in groundwaters and baseflow discharging to surface water to be generally low with only sporadic elevated concentrations attributed to localised point sources. Hydrocarbon VOCs (volatile organic compounds) were similarly absent or at low concentration attributable to their ready natural attenuation. Chlorinated VOCs, however, were widely encountered in groundwater, discharging as baseflow to surface water and impacting surface-water quality. This is attributed to their DNAPL (dense nonaqueous-phase liquid) properties and relative recalcitrance although there was some evidence of biodegradation, albeit insufficient to protect surface water and groundwater abstraction receptors. Some inorganic trends were evident across the various media; nitrate was the most significant quality concern. Generic conclusions are drawn on urban water-quality management and the need for risk-based management strategies to optimise use of urban, sporadically contaminated groundwater in conjunction with surface water highlighted.     

荷兰工业用地利用政策演变与对中国的启示:公共土地开发模式与可持续的土地开发利用

本文通过分析荷兰公共土地开发模式应用于工业用地开发的背景、特征和改革方向,对比中国工业用地中土地开发模式同荷兰的差异和存在的问题,探讨其对中国工业用地市场化改革的启示。采用文献分析法和比较分析法进行研究,发现荷兰工业用地开发利用中公共土地开发模式在历史上发挥了积极作用,其改革方向聚焦于存量工业用地开发、可持续土地开发利用和提高工业物业质量。中国与荷兰在工业用地开发利用上的共同点在于政府主导工业用地供给,差异性在于中国工业用地的地价远低于土地成本价,无法实现成本回收。因此,中国工业用地政策需要改变定价方式、推动工业不动产的业态形式多样化并提升物业质量,新增工业用地面积应与存量工业用地面积相挂钩。     

Determination of the bioaccessibility of chromium in Glasgow soil and the implications for human health risk assessment

The Unified Bioaccessibility Method (UBM), which simulates the fluids of the human gastrointestinal tract, was used to assess the oral bioaccessibility of Cr in 27 Glasgow soils. These included several contaminated with Cr(VI), the most toxic form of Cr, from the past disposal of chromite ore processing residue (COPR). The extraction was employed in conjunction with the subsequent determination of the bioaccessible Cr by ICP-OES and Cr(VI) by the diphenylcarbazide complexation colorimetric procedure. In addition, Cr(III)-containing species were determined by (i) HPLC-ICP-MS and (ii) ICP-OES analysis of gel electrophoretically separated components of colloidal and dissolved fractions from centrifugal ultrafiltration of extracts. Similar analytical procedures were applied to the determination of Cr and its species in extracts of the < 10 μm fraction of soils subjected to a simulated lung fluid test to assess the inhalation bioaccessibility of Cr.The oral bioaccessibility of Cr was typically greater by a factor of 1.5 in the ‘stomach’ (pH ~ 1.2) compared with the ‘stomach + intestine’ (pH ~ 6.3) simulation. On average, excluding two COPR-contaminated soil samples, the oral bioaccessibility (‘stomach’) was 5% of total soil Cr and, overall, similar to the soil Cr(VI) concentration. Chromium(VI) was not detected in the extracts, a consequence of pH- and soil organic matter-mediated reduction in the ‘stomach’ to Cr(III)-containing species, identified as predominantly Cr(III)-humic complexes. Insertion of oral bioaccessible fraction data into the SNIFFER human health risk assessment model identified site-specific assessment criteria (for residential land without plant uptake) that were exceeded by the soil total Cr (3680 mg kg^-1) and Cr(VI) (1485 mg kg^-1) concentration at only the most COPR-Cr(VI)-contaminated location. However, the presence of measurable Cr(VI) in the < 10 μm fraction of the two most highly Cr(VI)-contaminated soils demonstrated that inhalation of Cr(VI)-containing dust remains the most potentially harmful exposure route.     

Source apportionment of heavy metals and ionic contaminants in rainwater tanks in a subtropical urban area in Australia

Due to prolonged droughts in recent years, the use of rainwater tanks in urban areas has increased in Australia. In order to apportion sources of contribution to heavy metal and ionic contaminants in rainwater tanks in Brisbane, a subtropical urban area in Australia, monthly tank water samples (24 sites, 31 tanks) and concurrent bulk deposition samples (18 sites) were collected during mainly April 2007-March 2008. The samples were analysed for acid-soluble metals, soluble anions, total inorganic carbon and total organic carbon, and characteristics such as total solid and pH. The Positive Matrix Factorisation model, EPA PMF 3.0, was used to apportion sources of contribution to the contaminants. Four source factors were identified for the bulk deposition samples, including ‘crustal matter/sea salt’, ‘car exhausts/road side dust’, ‘industrial dust’ and ‘aged sea salt/secondary aerosols’. For the tank water samples, apart from these atmospheric deposition related factors which contributed in total to 65% of the total contaminant concentration on average, another six rainwater collection system related factors were identified, including ‘plumbing’, ‘building material’, ‘galvanizing’, ‘roofing’, ‘steel’ and ‘lead flashing/paint’ (contributing in total to 35% of the total concentration on average). The Australian Drinking Water Guideline for lead was exceeded in 15% of the tank water samples. The collection system related factors, in particular the ‘lead flashing/paint’ factor, contributed to 79% of the lead in the tank water samples on average. The concentration of lead in tank water was found to vary with various environmental and collection system factors, in particular the presence of lead flashing on the roof. The results also indicated the important role of sludge dynamics inside the tank on the quality of tank water.     

The difficulty of integrating land trusts in land use planning

We examine land-owning organizations’ choice of strategy for steering spatial development. There are two highly visible strategies to influence land use. The first one, acquisition, is direct; it consists of either gaining outright ownership of the land, or various forms of partial title, including conservation easements. The second one, regulation, is indirect; it relies on the legal instruments of public policy, in particular land use planning, to influence the behavior of landowners. Often linking these two strategies in a coherent way is a challenge. On the one hand, local authorities are empowered by the law to plan for conservation, but they are not well equipped to do so (lack of capacity, expertise, political will). On the other hand, many small conservation NGOs are active at the micro level with little concern for supra-local considerations.Focusing on an important private conservation effort in Southern Quebec, this article seeks to better understand land-owning organizations’ position toward land use planning. It shows how conservation NGOs, which rely on property rights to influence land use, position themselves within the broader regulatory context and attempt to coordinate their action at a regional scale in order to complement their acquisition strategy.     

A study on subjective preference to daylit residential indoor environment using conjoint analysis

This paper reports a study of the subjective preference to daylit indoor environment of a residential room using conjoint analysis, which is a highly reputable method used to analyze the mutual relationships among different attributes. Seven influential attributes were selected in the view of daylight performance assessment. They include ‘general brightness’, ‘desktop brightness’, ‘perceived glare’, ‘sunlight penetration’, ‘quality of view’, ‘user friendliness of shading control’ and ‘impact on energy’. Each of them has two levels. A total of eight combinations (profiles) of attributes with various levels were established by adopting fractional factorial design. Subjects were asked to rank-order the eight profiles according to their preference in terms of daylit environment of a residential room. The study aims at finding out the relative impact of the seven selected attributes to the overall daylight performance and seeking an organized assessment method for a residential daylit environment. Conjoint analysis found that the seven attributes have importance level in the order of ‘quality of view’, ‘general brightness’, ‘impact on energy’, ‘user friendliness of shading control’, ‘perceived glare’, ‘desktop brightness’ and ‘sunlight penetration’.