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  • Articles  (137)
  • risk assessment  (71)
  • sediment  (67)
  • Energy, Environment Protection, Nuclear Power Engineering  (137)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Risk analysis 19 (1999), S. 527-545 
    ISSN: 1539-6924
    Keywords: breast-feeding ; chlorinated compounds ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Exposure to persistent organochlorines in breast milk was estimated probabilistically for Canadian infants. Noncancer health effects were evaluated by comparing the predicted exposure distributions to published guidance values. For chemicals identified as potential human carcinogens, cancer risks were evaluated using standard methodology typically applied in Canada, as well as an alternative method developed under the Canadian Environmental Protection Act. Potential health risks associated with exposure to persistent organochlorines were quantitatively and qualitatively weighed against the benefits of breast-feeding. Current levels of the majority of contaminants identified in Canadian breast milk do not pose unacceptable risks to infants. Benefits of breast-feeding are well documented and qualitatively appear to outweigh potential health concerns associated with organochlorine exposure. Furthermore, the risks of mortality from not breast-feeding estimated by Rogan and colleagues exceed the theoretical cancer risks estimated for infant exposure to potential carcinogens in Canadian breast milk. Although levels of persistent compounds have been declining in Canadian breast milk, potentially significant risks were estimated for exposure to polychlorinated biphenyls, dibenzo-p-dioxins, and dibenzofurans. Follow-up work is suggested that would involve the use of a physiologically based toxicokinetic model with probabilistic inputs to predict dioxin exposure to the infant. A more detailed risk analysis could be carried out by coupling the exposure estimates with a dose–response analysis that accounts for uncertainty.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Risk analysis 19 (1999), S. 689-701 
    ISSN: 1539-6924
    Keywords: risk ; risk perception ; risk assessment ; risk communication ; risk management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Risk management has become increasingly politicized and contentious. Polarized views, controversy, and conflict have become pervasive. Research has begun to provide a new perspective on this problem by demonstrating the complexity of the concept “risk” and the inadequacies of the traditional view of risk assessment as a purely scientific enterprise. This paper argues that danger is real, but risk is socially constructed. Risk assessment is inherently subjective and represents a blending of science and judgment with important psychological, social, cultural, and political factors. In addition, our social and democratic institutions, remarkable as they are in many respects, breed distrust in the risk arena. Whoever controls the definition of risk controls the rational solution to the problem at hand. If risk is defined one way, then one option will rise to the top as the most cost-effective or the safest or the best. If it is defined another way, perhaps incorporating qualitative characteristics and other contextual factors, one will likely get a different ordering of action solutions. Defining risk is thus an exercise in power. Scientific literacy and public education are important, but they are not central to risk controversies. The public is not irrational. Their judgments about risk are influenced by emotion and affect in a way that is both simple and sophisticated. The same holds true for scientists. Public views are also influenced by worldviews, ideologies, and values; so are scientists' views, particularly when they are working at the limits of their expertise. The limitations of risk science, the importance and difficulty of maintaining trust, and the complex, sociopolitical nature of risk point to the need for a new approach—one that focuses upon introducing more public participation into both risk assessment and risk decision making in order to make the decision process more democratic, improve the relevance and quality of technical analysis, and increase the legitimacy and public acceptance of the resulting decisions.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Risk analysis 19 (1999), S. 711-726 
    ISSN: 1539-6924
    Keywords: variability ; exposure ; susceptibility ; risk assessment ; pharmacokinetics ; pharmacodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This paper reviews existing data on the variability in parameters relevant for health risk analyses. We cover both exposure-related parameters and parameters related to individual susceptibility to toxicity. The toxicity/susceptibility data base under construction is part of a longer term research effort to lay the groundwork for quantitative distributional analyses of non-cancer toxic risks. These data are broken down into a variety of parameter types that encompass different portions of the pathway from external exposure to the production of biological responses. The discrete steps in this pathway, as we now conceive them, are: •Contact Rate (Breathing rates per body weight; fish consumption per body weight) •Uptake or Absorption as a Fraction of Intake or Contact Rate •General Systemic Availability Net of First Pass Elimination and Dilution via Distribution Volume (e.g., initial blood concentration per mg/kg of uptake) •Systemic Elimination (half life or clearance) •Active Site Concentration per Systemic Blood or Plasma Concentration •Physiological Parameter Change per Active Site Concentration (expressed as the dose required to make a given percentage change in different people, or the dose required to achieve some proportion of an individual's maximum response to the drug or toxicant) •Functional Reserve Capacity–Change in Baseline Physiological Parameter Needed to Produce a Biological Response or Pass a Criterion of Abnormal Function Comparison of the amounts of variability observed for the different parameter types suggests that appreciable variability is associated with the final step in the process–differences among people in “functional reserve capacity.” This has the implication that relevant information for estimating effective toxic susceptibility distributions may be gleaned by direct studies of the population distributions of key physiological parameters in people that are not exposed to the environmental and occupational toxicants that are thought to perturb those parameters. This is illustrated with some recent observations of the population distributions of Low Density Lipoprotein Cholesterol from the second and third National Health and Nutrition Examination Surveys.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Risk analysis 19 (1999), S. 763-807 
    ISSN: 1539-6924
    Keywords: risk assessment ; probabilistic risk assessment ; performance assessment ; policy analysis ; history of technology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This article describes the evolution of the process for assessing the hazards of a geologic disposal system for radioactive waste and, similarly, nuclear power reactors, and the relationship of this process with other assessments of risk, particularly assessments of hazards from manufactured carcinogenic chemicals during use and disposal. This perspective reviews the common history of scientific concepts for risk assessment developed until the 1950s. Computational tools and techniques developed in the late 1950s and early 1960s to analyze the reliability of nuclear weapon delivery systems were adopted in the early 1970s for probabilistic risk assessment of nuclear power reactors, a technology for which behavior was unknown. In turn, these analyses became an important foundation for performance assessment of nuclear waste disposal in the late 1970s. The evaluation of risk to human health and the environment from chemical hazards is built on methods for assessing the dose response of radionuclides in the 1950s. Despite a shared background, however, societal events, often in the form of legislation, have affected the development path for risk assessment for human health, producing dissimilarities between these risk assessments and those for nuclear facilities. An important difference is the regulator's interest in accounting for uncertainty.
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  • 5
    ISSN: 1539-6924
    Keywords: risk perception ; CRESP ; trust ; DOE Savannah River site ; risk assessment ; stakeholder ; economic dependence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Environmental managers are increasingly charged with involving the public in the development and modification of policies regarding risks to human health and the environment. Involving the public in environmental decision making first requires a broad understanding of how and why the public perceives various risks. The Savannah River Stakeholder Study was conducted with the purpose of investigating individual, economic, and social characteristics of risk perceptions among those living near the Savannah River Nuclear Weapons Site. A number of factors were found to impact risk perceptions among those living near the site. One's estimated proximity to the site and relative river location surfaced as strong determinants of risk perceptions among SRS residents. Additionally, living in a quality neighborhood and demonstrating a willingness to accept health risks for economic gain strongly abated heightened risk perceptions.
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  • 6
    ISSN: 1539-6924
    Keywords: risk assessment ; uncertainty ; formaldehyde ; decision analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A call for risk assessment approaches that better characterize and quantify uncertainty has been made by the scientific and regulatory community. This paper responds to that call by demonstrating a distributional approach that draws upon human data to derive potency estimates and to identify and quantify important sources of uncertainty. The approach is rooted in the science of decision analysis and employs an influence diagram, a decision tree, probabilistic weights, and a distribution of point estimates of carcinogenic potency. Its results estimate the likelihood of different carcinogenic risks (potencies) for a chemical under a specific scenario. For this exercise, human data on formaldehyde were employed to demonstrate the approach. Sensitivity analyses were performed to determine the relative impact of specific levels and alternatives on the potency distribution. The resulting potency estimates are compared with the results of an exercise using animal data on formaldehyde. The paper demonstrates that distributional risk assessment is readily adapted to situations in which epidemiologic data serve as the basis for potency estimates. Strengths and weaknesses of the distributional approach are discussed. Areas for further application and research are recommended.
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  • 7
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    Risk analysis 19 (1999), S. 1157-1171 
    ISSN: 1539-6924
    Keywords: risk assessment ; transportation risk ; diesel exhaust ; fugitive dust ; vehicle emissions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract When the transportation risk posed by shipments of hazardous chemical and radioactive materials is being assessed, it is necessary to evaluate the risks associated with both vehicle emissions and cargo-related risks. Diesel exhaust and fugitive dust emissions from vehicles transporting hazardous shipments lead to increased air pollution, which increases the risk of latent fatalities in the affected population along the transport route. The estimated risk from these vehicle-related sources can often be as large or larger than the estimated risk associated with the material being transported. In this paper, data from the U.S. Environmental Protection Agency's Motor Vehicle-Related Air Toxics Study are first used to develop latent cancer fatality estimates per kilometer of travel in rural and urban areas for all diesel truck classes. These unit risk factors are based on studies investigating the carcinogenic nature of diesel exhaust. With the same methodology, the current per-kilometer latent fatality risk factor used in transportation risk assessments for heavy diesel trucks in urban areas is revised and the analysis expanded to provide risk factors for rural areas and all diesel truck classes. These latter fatality estimates may include, but are not limited to, cancer fatalities and are based primarily on the most recent epidemiological data available on mortality rates associated with ambient air PM-10 concentrations.
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  • 8
    ISSN: 1539-6924
    Keywords: municipal waste incineration ; risk assessment ; Monte-Carlo simulation ; time activity patterns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract During the modernization of the municipal waste incinerator (MWI, maximum capacity of 180,000 tons per year) of Metropolitan Grenoble (405,000 inhabitants), in France, a risk assessment was conducted, based on four tracer pollutants: two volatile organic compounds (benzene and 1, 1, 1 trichloroethane) and two heavy metals (nickel and cadmium, measured in particles). A Gaussian plume dispersion model, applied to maximum emissions measured at the MWI stacks, was used to estimate the distribution of these pollutants in the atmosphere throughout the metropolitan area. A random sample telephone survey (570 subjects) gathered data on time-activity patterns, according to demographic characteristics of the population. Life-long exposure was assessed as a time-weighted average of ambient air concentrations. Inhalation alone was considered because, in the Grenoble urban setting, other routes of exposure are not likely. A Monte Carlo simulation was used to describe probability distributions of exposures and risks. The median of the life-long personal exposures distribution to MWI benzene was 3.2·10−5 μg/m3 (20th and 80th percentiles = 1.5·10−5 and 6.5·10−5 μg/m3), yielding a 2.6·10−10 carcinogenic risk (1.2·10−10–5.4·10−10). For nickel, the corresponding life-time exposure and cancer risk were 1.8·10−4 μg/m3 (0.9.10−4 – 3.6·10−4 μg/m3) and 8.6·10−8 (4.3·10−8–17.3·10−8); for cadmium they were respectively 8.3·10−6 μg/m3 (4.0·10−6–17.6·10−6) and 1.5·10−8 (7.2·10−9–3.1·10−8). Inhalation exposure to cadmium emitted by the MWI represented less than 1% of the WHO Air Quality Guideline (5 ng/m3), while there was a margin of exposure of more than 109 between the NOAEL (150 ppm) and exposure estimates to trichloroethane. Neither dioxins nor mercury, a volatile metal, were measured. This could lessen the attributable life-long risks estimated. The minute (VOCs and cadmium) to moderate (nickel) exposure and risk estimates are in accord with other studies on modern MWIs meeting recent emission regulations, however.
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  • 9
    ISSN: 1539-6924
    Keywords: MeHg ; pharmacokinetics ; PBPK model ; variability ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract An analysis of the uncertainty in guidelines for the ingestion of methylmercury (MeHg) due to human pharmacokinetic variability was conducted using a physiologically based pharmacokinetic (PBPK) model that describes MeHg kinetics in the pregnant human and fetus. Two alternative derivations of an ingestion guideline for MeHg were considered: the U.S. Environmental Protection Agency reference dose (RfD) of 0.1 μg/kg/day derived from studies of an Iraqi grain poisoning episode, and the Agency for Toxic Substances and Disease Registry chronic oral minimal risk level (MRL) of 0.5 μg/kg/day based on studies of a fish-eating population in the Seychelles Islands. Calculation of an ingestion guideline for MeHg from either of these epidemiological studies requires calculation of a dose conversion factor (DCF) relating a hair mercury concentration to a chronic MeHg ingestion rate. To evaluate the uncertainty in this DCF across the population of U.S. women of child-bearing age, Monte Carlo analyses were performed in which distributions for each of the parameters in the PBPK model were randomly sampled 1000 times. The 1st and 5th percentiles of the resulting distribution of DCFs were a factor of 1.8 and 1.5 below the median, respectively. This estimate of variability is consistent with, but somewhat less than, previous analyses performed with empirical, one-compartment pharmacokinetic models. The use of a consistent factor in both guidelines of 1.5 for pharmacokinetic variability in the DCF, and keeping all other aspects of the derivations unchanged, would result in an RfD of 0.2 μg/kg/day and an MRL of 0.3 μg/kg/day.
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  • 10
    Electronic Resource
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    Springer
    Risk analysis 19 (1999), S. 577-584 
    ISSN: 1539-6924
    Keywords: risk assessment ; exposure point concentration ; bootstrapping ; gamma distribution ; lognormal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The U.S. Environmental Protection Agency (EPA) recommends the use of the one-sided 95% upper confidence limit of the arithmetic mean based on either a normal or lognormal distribution for the contaminant (or exposure point) concentration term in the Superfund risk assessment process. When the data are not normal or lognormal this recommended approach may overestimate the exposure point concentration (EPC) and may lead to unecessary cleanup at a hazardous waste site. The EPA concentration term only seems to perform like alternative EPC methods when the data are well fit by a lognormal distribution. Several alternative methods for calculating the EPC are investigated and compared using soil data collected from three hazardous waste sites in Montana, Utah, and Colorado. For data sets that are well fit by a lognormal distribution, values for the Chebychev inequality or the EPA concentration term may be appropriate EPCs. For data sets where the soil concentration data are well fit by gamma distributions, Wong's method may be used for calculating EPCs. The studentized bootstrap-t and Hall's bootstrap-t transformation are recommended for EPC calculation when all distribution fits are poor. If a data set is well fit by a distribution, parametric bootstrap may provide a suitable EPC.
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  • 11
    ISSN: 1539-6924
    Keywords: regulation ; radioactive waste ; performance assessment ; risk assessment ; regulatory assessment ; bias evaluation ; international collaboration ; underground disposal ; quantitative risk analysis ; public debate ; decision process
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Much has been written about the development and application of quantitative methods for estimating under uncertainty the long-term radiological performance of underground disposal of radioactive wastes. Until recently, interest has been focused almost entirely on the technical challenges regardless of the role of the organization responsible for these analyses. Now the dialogue between regulators, the repository developer or operator, and other interested parties in the decision-making process receives increasing attention, especially in view of some current difficulties in obtaining approvals to construct or operate deep facilities for intermediate or high-level wastes. Consequently, it is timely to consider the options for regulators' review and evaluation of safety submissions, at the various stages in the site selection to repository closure process, and to consider, especially, the role for performance assessment (PA) within the programs of a regulator both before and after delivery of such a submission. The origins and broad character of present regulations in the European Union (EU) and in the OECD countries are outlined and some regulatory PA reviewed. The issues raised are discussed, especially in regard to the interpretation of regulations, the dangers from the desire for simplicity in argument, the use of regulatory PA to review and challenge the PA in the safety case, and the effects of the relationship between proponent and regulator. Finally, a very limited analysis of the role of PA in public hearings is outlined and recommendations are made, together with proposals for improving the mechanisms for international collaboration on technical issues of regulatory concern.
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  • 12
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    Risk analysis 18 (1998), S. 679-688 
    ISSN: 1539-6924
    Keywords: Air quality ; benchmarking ; best available control technology ; contaminant exposure ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Although occupational exposure limits are sought to establish health-based standards, they do not always give a sufficient basis for planning an indoor air climate that is good and comfortable for the occupants in industrial work rooms. This paper considers methodologies by which the desired level, i.e., target level, of air quality in industrial settings can be defined, taking into account feasibility issues. Risk assessment based on health criteria is compared with risk-assessment based on “Best Available Technology” (BAT). Because health-based risk estimates at low concentration regions are rather inaccurate, the technology-based approach is emphasized. The technological approach is based on information on the prevailing concentrations in industrial work environments and the benchmark air quality attained with the best achievable technology. The prevailing contaminant concentrations are obtained from a contaminant exposure databank, and the benchmark air quality by field measurements in industrial work rooms equipped with advanced ventilation and production technology. As an example, the target level assessment has been applied to formaldehyde, total inorganic dust and hexavalent chromium, which are common contaminants in work room air.
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  • 13
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    Risk analysis 19 (1999), S. 23-32 
    ISSN: 1539-6924
    Keywords: Software failures ; software hazard analysis ; safety-critical systems ; risk assessment ; context
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract As the use of digital computers for instrumentation and control of safety-critical systems has increased, there has been a growing debate over the issue of whether probabilistic risk assessment techniques can be applied to these systems. This debate has centered on the issue of whether software failures can be modeled probabilistically. This paper describes a “context-based” approach to software risk assessment that explicitly recognizes the fact that the behavior of software is not probabilistic. The source of the perceived uncertainty in its behavior results from both the input to the software as well as the application and environment in which the software is operating. Failures occur as the result of encountering some context for which the software was not properly designed, as opposed to the software simply failing “randomly.” The paper elaborates on the concept of “error-forcing context” as it applies to software. It also illustrates a methodology which utilizes event trees, fault trees, and the Dynamic Flowgraph Methodology (DFM) to identify “error-forcing contexts” for software in the form of fault tree prime implicants.
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  • 14
    ISSN: 1539-6924
    Keywords: Benchmark ; mercury ; risk assessment ; epidemiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This paper presents benchmark (BMD) calculations and additional regression analyses of data from a study in which scores from 26 scholastic and psychological tests administered to 237 6- and 7-year-old New Zealand children were correlated with the mercury concentration in their mothers' hair during pregnancy. The original analyses of five test scores found an association between high prenatal mercury exposure and decreased test performance, using category variables for mercury exposure. Our regression analyses, which utilized the actual hair mercury level, did not find significant associations between mercury and children's test scores. However, this finding was highly influenced by a single child whose mother's mercury hair level (86 mg/kg) was more than four times that of any other mother. When that child was omitted, results were more indicative of a mercury effect and scores on six tests were significantly associated with the mothers' hair mercury level. BMDs calculated from five tests ranged from 32 to 73 mg/kg hair mercury, and corresponding BMDLs (95% lower limits on BMDs) ranged from 17 to 24 mg/kg. When the child with the highest mercury level was omitted, BMDs ranged from 13 to 21 mg/kg, and corresponding BMDLs ranged from 7.4 to 10 mg/kg.
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  • 15
    ISSN: 1539-6924
    Keywords: Remediation ; stakeholders ; deliberation ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The National Research Council has recommended the use of an analytic/deliberative decision-making process in environmental restoration decisions that involve multiple stakeholders. This work investigates the use of the results of risk assessment and multiattribute utility analysis (the “analysis”) in guiding the deliberation. These results include the ranking of proposed remedial action alternatives according to each stakeholder's preferences, as well as the identification of the major reasons for these rankings. The stakeholder preferences are over a number of performance measures that include the traditional risk assessment metrics, e.g., individual worker risk, as well as programmatic, cultural, and cost-related impacts. Based on these results, a number of proposals are prepared for consideration by the stakeholders during the deliberation. These proposals are the starting point for the formulation of actual recommendations by the group. In our case study, these recommendations included new remedial action alternatives that were created by the stakeholders after an extensive discussion of the detailed analytical results.
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  • 16
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    Risk analysis 19 (1999), S. 327-334 
    ISSN: 1539-6924
    Keywords: Biological introductions ; binucleate Rhizoctonia ; biocontrol ; risk assessment ; seedlings ; susceptibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This article describes an application of a method for assessing risks associated with the introduction of an organism into a new environment. The test organism was a binucleate Rhizoctonia fungal isolate that has potential for commercial development as a biological control agent for damping-off diseases in bedding plants. A test sample of host plant species was selected using the centrifugal phylogenetic host range principles, but with an emphasis on economic species. The effect of the fungus on the plant was measured for each species and expressed on a logarithmic scale. The effects on weights of shoots and roots per container were not normally distributed, nor were the effects on the number of plants standing (those which survived). Statements about the effect on the number standing and the shoot weight per container involved using the observed (empirical) distribution. This is illustrated with an example. Problems were encountered in defining the population of species at risk, and in deciding how this population should be formally sampled. The limitations of the method are discussed.
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  • 17
    ISSN: 1539-6924
    Keywords: dose-response ; models ; food-borne ; pathogens ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Food-related illness in the United States is estimated to affect over six million people per year and cost the economy several billion dollars. These illnesses and costs could be reduced if minimum infectious doses were established and used as the basis of regulations and monitoring. However, standard methodologies for dose-response assessment are not yet formulated for microbial risk assessment. The objective of this study was to compare dose-response models for food-borne pathogens and determine which models were most appropriate for a range of pathogens. The statistical models proposed in the literature and chosen for comparison purposes were log-normal, log-logistic, exponential, β-Poisson and Weibull-Gamma. These were fit to four data sets also taken from published literature, Shigella flexneri, Shigella dysenteriae,Campylobacter jejuni, and Salmonella typhosa, using the method of maximum likelihood. The Weibull-gamma, the only model with three parameters, was also the only model capable of fitting all the data sets examined using the maximum likelihood estimation for comparisons. Infectious doses were also calculated using each model. Within any given data set, the infectious dose estimated to affect one percent of the population ranged from one order of magnitude to as much as nine orders of magnitude, illustrating the differences in extrapolation of the dose response models. More data are needed to compare models and examine extrapolation from high to low doses for food-borne pathogens.
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  • 18
    ISSN: 1539-6924
    Keywords: ethylene oxide ; risk assessment ; epidemiology ; cancer guidelines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Ethylene oxide (EO) research has significantly increased since the 1980s, when regulatory risk assessments were last completed on the basis of the animal cancer chronic bioassays. In tandem with the new scientific understanding, there have been evolutionary changes in regulatory risk assessment guidelines, that encourage flexibility and greater use of scientific information. The results of an updated meta-analysis of the findings from 10 unique EO study cohorts from five countries, including nearly 33,000 workers, and over 800 cancers are presented, indicating that EO does not cause increased risk of cancers overall or of brain, stomach or pancreatic cancers. The findings for leukemia and non-Hodgkin's lymphoma (NHL) are inconclusive. Two studies with the requisite attributes of size, individual exposure estimates and follow up are the basis for dose-response modeling and added lifetime risk predictions under environmental and occupational exposure scenarios and a variety of plausible alternative assumptions. A point of departure analysis, with various margins of exposure, is also illustrated using human data. The two datasets produce remarkably similar leukemia added risk predictions, orders of magnitude lower than prior animal-based predictions under conservative, default assumptions, with risks on the order of 1 × 10−6 or lower for exposures in the low ppb range. Inconsistent results for “lymphoid” tumors, a non-standard grouping using histologic information from death certificates, are discussed. This assessment demonstrates the applicability of the current risk assessment paradigm to epidemiological data.
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  • 19
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    Risk analysis 19 (1999), S. 1223-1234 
    ISSN: 1539-6924
    Keywords: risk assessment ; standard-setting ; carcinogens ; OSHA ; ACGIH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract For carcinogens, this paper provides a quantitative examination of the roles of potency and weight-of-evidence (WOE) in setting permissible exposure limits (PELs) at the U.S. Occupational Safety and Health Administration (OSHA) and threshold limit values (TLVs) at the private American Conference of Governmental Industrial Hygienists (ACGIH). On normative grounds, both of these factors should influence choices about the acceptable level of exposures. Our major objective is to examine whether and in what ways these factors have been considered by these organizations. A lesser objective is to identify outliers, which might be candidates for further regulatory scrutiny. Our sample (N=48) includes chemicals for which EPA has estimated a unit risk as a measure of carcinogenic potency and for which OSHA or the ACGIH has a PEL or TLV. Different assessments of the strength of the evidence of carcinogenicity were obtained from EPA, ACGIH, and the International Agency for Research on Cancer. We found that potency alone explains 49% of the variation in PELs and 62% of the variation in TLVs. For the ACGIH, WOE plays a much smaller role than potency. TLVs set by the ACGIH since 1989 appear to be stricter than earlier TLVs. We suggest that this change represents evidence that the ACGIH had responded to criticisms leveled at it in the late 1980s for failing to adopt sufficiently protective standards. The models developed here identify 2-nitropropane, ethylene dibromide, and chromium as having OSHA PELs significantly higher than predicted on the basis of potency and WOE.
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  • 20
    ISSN: 1539-6924
    Keywords: Extreme events ; risk assessment ; risk management ; extreme value theory ; judgmental distributions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In this paper, we review methods for assessing and managing the risk of extreme events, where “extreme events” are defined to be rare, severe, and outside the normal range of experience of the system in question. First, we discuss several systematic approaches for identifying possible extreme events. We then discuss some issues related to risk assessment of extreme events, including what type of output is needed (e.g., a single probability vs. a probability distribution), and alternatives to the probabilistic approach. Next, we present a number of probabilistic methods. These include: guidelines for eliciting informative probability distributions from experts; maximum entropy distributions; extreme value theory; other approaches for constructing prior distributions (such as reference or noninformative priors); the use of modeling and decomposition to estimate the probability (or distribution) of interest; and bounding methods. Finally, we briefly discuss several approaches for managing the risk of extreme events, and conclude with recommendations and directions for future research.
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  • 21
    ISSN: 1539-6924
    Keywords: Market response ; risk assessment ; airplane accidents ; airline industry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The risk of catastrophic failures, for example in the aviation and aerospace industries, can be approached from different angles (e.g., statistics when they exist, or a detailed probabilistic analysis of the system). Each new accident carries information that has already been included in the experience base or constitutes new evidence that can be used to update a previous assessment of the risk. In this paper, we take a different approach and consider the risk and the updating from the investor's point of view. Based on the market response to past airplane accidents, we examine which ones have created a “surprise response” and which ones are considered part of the risk of the airline business as previously assessed. To do so, we quantify the magnitude and the timing of the observed market response to catastrophic accidents, and we compare it to an estimate of the response that would be expected based on the true actual cost of the accident including direct and indirect costs (“full-cost information” response). First, we develop a method based on stock market data to measure the actual market response to an accident and we construct an estimate of the “full-cost information” response to such an event. We then compare the two figures for the immediate and the long-term response of the market for the affected firm, as well as for the whole industry group to which the firm belongs. As an illustration, we analyze a sample of ten fatal accidents experienced by major US domestic airlines during the last seven years. In four cases, we observed an abnormal market response. In these instances, it seems that the shareholders may have updated their estimates of the probability of a future accident in the affected airlines or more generally of the firm's future business prospects. This market reaction is not always easy to explain much less to anticipate, a fact which management should bear in mind when planning a firm's response to such an event.
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  • 22
    ISSN: 1539-6924
    Keywords: Uncertainty ; variability ; risk assessment ; risk management ; ozone ; clean air act ; social policy ; analysis of benefits and costs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This paper is a challenge from a pair of lifelong technical specialists in risk assessment for the risk-management community to better define social decision criteria for risk acceptance vs. risk control in relation to the issues of variability and uncertainty. To stimulate discussion, we offer a variety of “straw man” proposals about where we think variability and uncertainty are likely to matter for different types of social policy considerations in the context of a few different kinds of decisions. In particular, we draw on recent presentations of uncertainty and variability data that have been offered by EPA in the context of the consideration of revised ambient air quality standards under the Clean Air Act.
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    Risk analysis 19 (1999), S. 135-152 
    ISSN: 1539-6924
    Keywords: Probability ; uncertainty ; data ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Risk assessors attempting to use probabilistic approaches to describe uncertainty often find themselves in a data-sparse situation: available data are only partially relevant to the parameter of interest, so one needs to adjust empirical distributions, use explicit judgmental distributions, or collect new data. In determining whether or not to collect additional data, whether by measurement or by elicitation of experts, it is useful to consider the expected value of the additional information. The expected value of information depends on the prior distribution used to represent current information; if the prior distribution is too narrow, in many risk-analytic cases the calculated expected value of information will be biased downward. The well-documented tendency toward overconfidence, including the neglect of potential surprise, suggests this bias may be substantial. We examine the expected value of information, including the role of surprise, test for bias in estimating the expected value of information, and suggest procedures to guard against overconfidence and underestimation of the expected value of information when developing prior distributions and when combining distributions obtained from multiple experts. The methods are illustrated with applications to potential carcinogens in food, commercial energy demand, and global climate change.
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    Stochastic environmental research and risk assessment 11 (1997), S. 193-210 
    ISSN: 1436-3259
    Keywords: Turbulence ; sediment ; fluvial ; river ; bursting process ; statistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Entrainment of sediment particles from channel beds into the channel flow is influenced by the characteristics of the flow turbulence which produces stochastic shear stress fluctuations at the bed. Recent studies of the structure of turbulent flow has recognized the importance of bursting processes as important mechanisms for the transfer of momentum into the laminar boundary layer. Of these processes, the sweep event has been recognized as the most important bursting event for entrainment of sediment particles as it imposes forces in the direction of the flow resulting in movement of particles by rolling, sliding and occasionally saltating. Similarly, the ejection event has been recognized as important for sediment transport since these events maintain the sediment particles in suspension. In this study, the characteristics of bursting processes and, in particular, the sweep event were investigated in a flume with a rough bed. The instantaneous velocity fluctuations of the flow were measured in two-dimensions using a small electromagnetic velocity meter and the turbulent shear stresses were determined from these velocity fluctuations. It was found that the shear stress applied to the sediment particles on the bed resulting from sweep events depends on the magnitude of the turbulent shear stress and its probability distribution. A statistical analysis of the experimental data was undertaken and it was found necessary to apply a Box-Cox transformation to transform the data into a normally distributed sample. This enabled determination of the mean shear stress, angle of action and standard error of estimate for sweep and ejection events. These instantaneous shear stresses were found to be greater than the mean flow shear stress and for the sweep event to be approximately 40 percent greater near the channel bed. Results from this analysis suggest that the critical shear stress determined from Shield's diagram is not sufficient to predict the initiation of motion due to its use of the temporal mean shear stress. It is suggested that initiation of particle motion, but not continuous motion, can occur earlier than suggested by Shield's diagram due to the higher shear stresses imposed on the particles by the stochastic shear stresses resulting from turbulence within the flow.
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    Stochastic environmental research and risk assessment 8 (1994), S. 57-77 
    ISSN: 1436-3259
    Keywords: Stochastic transport ; risk assessment ; concentration CDF ; exceedance probabilities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract This paper presents the principles underlying a recently developed numerical technique for modeling transport in heterogeneous porous media. The method is then applied to derive the concentration mean and variance, the concentration CDF, exceedance probabilities and exposure time CDF, which are required by various regulatory agencies for risk and performance assessment calculations. The dependence of the various statistics on elapsed travel time, location in space, the dimension of the detection volume, natural variability and pore-scale dispersion is investigated and discussed.
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    Natural hazards 22 (2000), S. 117-138 
    ISSN: 1573-0840
    Keywords: fatalities ; flood ; bushfire ; heatwave ; eastern Australia ; ENSO ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The interannual variability of flood, bushfire andheatwave fatality data for eastern Australia duringthe period 1876–1991 was analysed with respect to thephase of the El Niño-Southern Oscillation (ENSO)and the associated values of the Southern OscillationIndex (SOI). Heatwaves were found to be the mostserious peril in terms of the total number offatalities, while floods ranked first in the fatalityevent day statistics. None of the three monthly(absolute value) fatality data sets showed significantcorrelations with the corresponding values of the SOI,while the correlation analysis of annual (July toJune) data led to significant correlation coefficientsof 0.5 for floods and -0.3 for bushfires. AdditionalSOI value-related classification of the standardisedfatality event days into several ENSO categoriesconfirmed the correlation trends by showing anincrease (decrease) in the standardised bushfire(flood) fatality event day frequencies with increasingvalues of the SOI. In contrast to that, thestandardised heatwave fatality data showed aninconclusive distribution pattern, which hints at theinfluence of other possible factors (such as airpollution) on heatwave-related fatality numbers. The results of a risk assessment analysis have shownthat the probability of reaching the mean annualnumber of flood-fatality event days is roughly fourtimes higher during La Niña seasons (80%) thanthe corresponding probability associated with ElNiño periods (18%). The correspondingprobabilities associated with the mean bushfire andheatwave fatality event days displayed a reversedpattern, with the probabilities of El Niño-relatedyears being roughly twice as high as those associatedwith La Niña seasons (70% and 30% for bushfires,and 60% and 25% for heatwaves, respectively).Further probability calculations performed on thetotals of fatalities from all three perils identifiedthe La Niña years as potentially the mostdangerous in terms of suffering fatalities from theseperils. Furthermore, they highlighted the significantdifferences between the means of fatality event daynumbers recorded during years of extreme SOI values(9.8 for La Niña, and 9.1 for El Niño seasons)and those marked by near-zero SOI values (6.6). Themajor reason for the increase in risk associated withextreme ENSO phases was the higher variability ofthese perils during the respective seasons.
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    Natural hazards 21 (2000), S. 347-360 
    ISSN: 1573-0840
    Keywords: volcanic hazard ; risk assessment ; GIS ; physical simulation models ; information systems ; emergency planning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The incorporation of a set ofcomputer-based tools, such as Geographical InformationSystems and physical models, to the field of riskassessment, introduces a new perspective in thevolcanic risk maps production, increasing the analysisand modelling capabilities available through theapplication of conventional methodologies. Amethodology adapted to the requirements andcharacteristics of the new operating environment hasbeen applied at Tenerife island (Canary Islands,Spain) to carry out a study devoted to analyse thesuitability of these tools for near real-timemanagement of volcanic crises. With this in mind, aseries of potential eruption scenarios have beenselected to identify and characterise which elementsat risk would prove most vulnerable against a specificvolcanic phenomenon, depending on the socio-economiccharacteristics of the area affected and the resultingdistribution of the volcanic products. This kind ofinformation is fundamental to update, adapt or produceeffective risk management and emergency plans orprotocols, where the measures to mitigate or fightagainst a specific volcanic disaster have to be taken,incorporating the existing knowledge of the phenomenonbehaviour and taking into account their potentialeffects on the area of interest.
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    Natural hazards 20 (1999), S. 279-294 
    ISSN: 1573-0840
    Keywords: risk assessment ; groundwater contamination ; vulnerability ; GIS ; hazard ; economic ; value
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The groundwater contamination risk map of a samplealluvial area was produced by using the IlwisGeographical Information System (GIS) to construct andto overlay thematic maps. The risk map has beenderived from the vulnerability map, the hazard map,where the potential contaminating sources wereidentified, and the socio-economic value of thegroundwater resource, represented by the wells. Thegroundwater quality map allowed thereliability of hazard and risk maps to be tested. The final map shows interesting results and stressesthe need for the GIS to test and improve on thegroundwater contamination risk assessment methods.
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    Natural hazards 21 (2000), S. 225-245 
    ISSN: 1573-0840
    Keywords: risk assessment ; emergency preparedness ; legislative measures ; flood prevention and mitigation ; forecasting and warning ; control structure ; public participation ; Canada ; Red River Valley
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The prevention and/or mitigation offlood disasters requires continual research, numerouscapital investment decisions, and high-qualitymaintenance and modifications of flood-controlstructures. In addition, institutional and privatepreparedness is needed. The experience offlood-control in North America has shown mixedoutcomes: while flood frequency has declined duringthe last few decades, the economic losses havecontinued to rise. Recent catastrophic floods havealso been linked to major structural interventions inthe region. The flood diversions may cause harmfuleffects upon the floodplain inhabitants by influencingflood levels in areas which are not normallyflood-prone. The increasing vulnerability of thefloodplain inhabitants poses new challenges and raisesquestions concerning the existing risk assessmentmethods, institutional preparedness and responses todisaster-related public emergencies, and local-levelpublic involvement in flood mitigation efforts. In the context of the catastrophic 1997 floods of theRed River Valley, Manitoba, Canada, this researchfocuses on two aspects of flood-related emergencygovernance and management: (i) the functions andeffectiveness of control structures, and (ii) theroles, responsibilities and effectiveness oflegislative and other operational measures. The studyconcludes that the flood-loss mitigation measures,both in terms of effects of control structures andinstitutional interventions for emergency evacuation,were not fully effective for ensuring the well-beingand satisfaction of floodplain inhabitants. Althoughorganizational preparedness and mobilization to copewith the 1997 flood emergency was considerable, theirsuccess during the onset of the flood event waslimited. Lack of communication and understandingbetween institutions, a reluctance to implementup-to-date regulations, and minimal publicparticipation in the emergency decision-making processall contributed to the difficulties experienced byfloodplain inhabitants.
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  • 30
    ISSN: 1573-0840
    Keywords: Tsunami catalog ; precursors ; warning system ; public education ; risk assessment ; Mexico ; Mesoamerican subduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract From an inspection of all tide gauge records for the western coast of Mexico over the last 37 years, a data base of all recorded tsunamis was made. Information on relevant historical events dating back two centuries, using newspaper archives, previous catalogs, and local witness interviews, was added to produce a catalog of tsunamis for the western coast of Mexico. A description of the 1932 Cuyutlán tsunami is given. This is considered to be the most destructive local tsunami which has ever occurred in the region for which historical accounts are available. It was preceded by two precursor events, a not uncommon occurrence in that zone. A summary of the generation and coastal effects from the 1985 Michoacán tsunamis is also given. These Michoacán tsunamis are the most recent local events in that zone. This information, and knowledge of local undersea faulting characteristics along the Mexican Pacific coast, leads to a clear differentiation of two zones of potential tsunami hazard: locally generated tsunamis south of the Rivera fracture, in the Cocos plate subsidence region, and remotely generated tsunamis north of this zone. Based on this zonation, two types of tsunami warning systems are proposed: real-time for the southern zone, and delayed-time for the northern. A description is provided of the Baja California Regional Tsunami Warning System that is presently operational in the northern zone. Several major industrial ports and tourist resort areas are located in the southern zone, and are therefore most vulnerable to local destructive tsunamis. Some of these sites represent important socioeconomic resources for Mexico, and have therefore been chosen for a vulnerability assessment and microzonation risk analysis. Land use patterns are identified, risks defined, and recommendations to minimize future tsunami impact are given. One case is illustrated.
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    Environmental and resource economics 11 (1998), S. 489-501 
    ISSN: 1573-1502
    Keywords: cost-benefit analysis ; environmental policy ; precautionary principle ; risk assessment ; sustainable development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Economics
    Notes: Abstract Revisions to the European Treaty of Union require some form of environmental appraisal – primarily risk assessment and cost-benefit analysis – of regulatory initiatives by the European Commission. A retrospective look at the emergence of environmental appraisal also shows that, while the Commission has made great advances in introducing cost-benefit or cost-effectiveness appraisals in recent years, past environmental decisions and overall environmental policy have not been informed by systematic appraisal techniques. Nor is it clear what role is now being played by risk assessments. While it is impossible to gauge the extent to which systematic appraisal procedures will save on regulatory and compliance expenditures, some indications are provided of the costs of past neglect of these procedures.
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    Water, air & soil pollution 85 (1995), S. 167-176 
    ISSN: 1573-2932
    Keywords: air pollution ; health effects ; risk assessment
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    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Based on combined information available from air quality monitoring data and long-range transport models, European population exposure to SO2, NO2 and O3 has been estimated. This information has been combined with the results of epidemiological studies assessing strength of association between the exposure and health effects to estimate an impact of the pollution on health in Europe. The analysis indicates that a considerable number of health problems, ranging from mild irritation of the respiratory system to increased mortality, can be attributed to short-term peaks of pollution observed in Europe. Chronic impacts of prolonged elevated SO2 levels on lung function are estimated to occur in close to10 million people in Europe.
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  • 33
    ISSN: 1573-2932
    Keywords: mercury ; foodplains ; humic substances ; complexation ; speciation ; mobilization ; risk assessment ; water solubility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The water-mobilizability of mercury from contaminated floodplain soils of the river Elbe in Northern Germany was evaluated by batch extraction experiments. It was shown that only a small amount of the total mercury present (about 1% per extraction) can be mobilized by water. This mercury is transported entirely in the form of a complex bound to humic acids (HA); particulates and fulvic acids (FA) did not seem to contribute to the process. It could not be removed from the HA even at pH 1, indicating an extremely strong complexation e.g. by sulfur-containing ligands. Furthermore, the influence of pH on the mobilization was investigated. It was found that in the range of natural pH-values, there was no observable effect of pH on the mobilization of either mercury or dissolved organic carbon (DOC). This surprising finding is explained by an unexpectedly high buffering capacity of the humics, both in the acidic and in the alkaline region. Only at extreme pH-values there was deviation from this behaviour. In contrast to other heavy metals, the amount of mobilized mercury decreases at pH 〈 3; and at pH 〉 12, an increased mobilization of mercury was observed because the humics are mobilized completely, accompanied by the total amount of mercury bound to them.
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    Water, air & soil pollution 99 (1997), S. 81-88 
    ISSN: 1573-2932
    Keywords: channel ; bend ; sediment ; size ; gradation ; sorting ; bed ; topography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Variations of sediment size and its gradation of the bed surface layer in a channel bend with nonuniform sediment are investigated experimentally. Four groups of sediment with the same initial median diameter (D0) but different initial size gradation (σ0) have been used for experiments which were run until the equilibrium bed topography was achieved. Analyses of experimental data have yielded the following results: (1) The time of equilibrium for bed evolution decreases as σ0 increases; (2) the median size of sediment (D) for a given section in the bend increases with increasing distance from the inner bank towards the outer bank, and it also increases with increasing σ0; (3) the value of D/D0 along the inner bank decreases with increasing σ0, and it also shows a gradual decrease in the upper half of the bend and a slight recovery in the lower half; and (5) the transverse variation of σ value exhibits a general trend increasing from the inner bank towards the outer bank.
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  • 35
    ISSN: 1573-2932
    Keywords: phosphorus ; P flux ; microbial activity ; redox ; simulation ; Lake Kinneret ; sediment ; accumulative P release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Different factors which interactively control the flux of soluble reactive phosphorus (SRP) at the sediment-water interface (SWI) of Lake Kinneret were studied seasonally. The influence of pH, Eh and microbial activity on SRP flux at the SWI was investigated by manipulating the conditions in the overlying water of intact sediment cores. The calculated diffusive SRP flux out of the sediment was lower in cores sampled during winter and spring than during the period of amixis. Potential SRP release, as measured in the absence of microbial activity, was strongly enhanced upon the transition from oxic to anoxic conditions indicating P release from iron(III)-bound phosphorus. In spring and summer cores, an enhanced SRP flux from sediments at pH 7 in comparison to pH 8 indicated P release from carbonate-bound P which sedimented previously as result of high pH values during the algal spring bloom. Microbial uptake at the SWI was the most important sink for SRP and no net-flux occured under oxic conditions. The higher net-flux of P under anoxic conditions was linked to carbon limitation of the bacteria at the SWI.
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    Water, air & soil pollution 99 (1997), S. 457-464 
    ISSN: 1573-2932
    Keywords: sediment ; phosphorus ; fractionation ; release ; humic lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Lake Flosek (north-eastern part of Poland) is a small shallow and without outflow lake which has been limed in 1970. The concentration of Ca was increased from 3-4 mg L-1 to 17 mg L-1 in the water and from 0.2-0.3% dry weight to 0.9-1.7% dry weight in sediments (5 cm upper layer) due to CaCO3 addition to the lake. In the spring-summer seasons of 1992 and 1993, an experimental study was conducted in Lake Flosek to assess the capacity of bottom sediments to uptake and release mineral phosphorus. The rate of phosphorus exchange between sediments and near-bottom water was experimentally measured under conditions of high (100%), and of reduced (10%) oxygen saturation in near-bottom water. To determine the component of sediments responsible for the uptake of most phosphorus, the proportions of phosphorus forms in sediments were analysed. Sediments of Lake Flosek showed a slight tendency to release phosphates. The rate of this process was similar under high (100%) and low (10%) oxygen saturations ranging from - 0.161 to + 0.200 mg P m-2 d-1. This is much lower (by 1-2 orders of magnitude) than reported from other harmonic, non-humic lakes. In the total phosphorus pool, the highest content of phosphorus was found in the organic and residual phosphorus fractions (over 70% of the total phosphorus in sediments). The largest part of the readily extractable phosphorus was found in the fraction bound to Al and humic substances (41%). Both these fractions determine a weak exchange of phosphorus between sediments and water. No difference in P-release related to P-fraction compound was found in the cores taken from three sites in the lake.
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    Water, air & soil pollution 99 (1997), S. 477-486 
    ISSN: 1573-2932
    Keywords: sediment ; nitrogen ; phosphorus ; organic matter ; cluster analysis ; Gulf of Finland ; estuaries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Dry weight (DW), ignition loss (IL) and concentrations of total nitrogen (TN) and total phosphorus (TP) of the sediment surface layer (0 to 10 cm, 1 cm slices) were analyzed from 20 sites in the eastern Gulf of Finland. The distance of the sampling sites from the mouth of the River Neva explained the nutrient concentrations of the sediments well, while the effect of water depth was negligible. The increase of TN and the decrease of TP along the transect from the river mouth towards the open Gulf were caused by the diminishing share of allochthonous material supplied from the River Neva. The mean TN concentration of the different accumulation areas was about 40 % higher in the sediment surface than in the deeper layer (9 to 10 cm). The corresponding difference for TP varied from 53 to 56 %. The results suggest considerable netflux of nutrients from sediment to water. The net sediment accumulation of nutrients were estimated as 6.0 g m-2 a-1 of N and 1.7 g m-2 a-1 of P corresponding 22 000 t a-1 of N and 6 100 t a-1 of P for the whole eastern Gulf.
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  • 38
    ISSN: 1573-2932
    Keywords: reservoir of heated water ; contamination ; cadmium ; copper ; nickel ; sediment ; water ; enrichment factor ; geoaccumulation index ; contamination factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In this paper, the contamination degree of the Rybnik Reservoir with cadmium, copper and nickel was analyzed. Quality of the water from the reservoir was determined by drawing comparisons between the metal content in the water and both the officially permitted levels (contamination factor) and levels of metals occurring in the water of non-contaminated areas (enrichment factor). Contamination of bottom sediment with chosen metals was analyzed with reference to the metal content in mudstone (geoaccumulation index, enrichment factor, contamination factor). Trends towards changing the metal content in the bottom sediment was analyzed by determining the enrichment factor of the surface layer of the bottom sediments in relation to a deeper layer. Enrichment of the bottom sediments with metals coming from the water was also determined.
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  • 39
    ISSN: 1573-2932
    Keywords: Aquaculture ; aggregation ; flocculation ; grain size ; sediment ; trace metal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Grain size is the most basic of classification criteria for sediments. The size distribution of a given sediment records the physical transport processes involved in its formation. By using precise grain size analysis and the model of Kranck et al. (1996a,b), it is possible to break down a sediment into the three major components from which it was formed: material deposited as flocs, material deposited as single grains from suspension, and material carried under higher energy conditions. With this method, both the amount of material deposited in a flocculated state and the maximum size, or floc limit, of the particles composing the floc can be determined. Changes in floc limit indicate changes in the aggregation dynamics of the system. As most trace metals and many other contaminants associate closely with the fine particle fraction of sediments, it is important to determine both the areal distribution and reworking history of the floc settled portion of a sediment. This paper discusses the application of the method to coastal inlets in Atlantic Canada and examines the relationship between proportion of floc-settled material and trace metal concentrations. Disaggregated inorganic grain size distributions are also used to illustrate changes in the aggregation dynamics in areas of intense aquaculture.
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  • 40
    ISSN: 1573-2932
    Keywords: mercury ; methylmercury ; sediment ; polychaete ; Nereis diversicolor ; methylation ; bioaccumulation ; Scheldt estuary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Total mercury (Hg) and methylmercury (MeHg) concentrations were determined in sediments and in the polychaete worm Nereis diversicolor at 13 stations of a brackish water intertidal mudflat of the Scheldt estuary. Hg and MeHg concentrations in sediments ranged from 144 to 1192 ng g−1 dw and from 0.8 to 6 ng g−1 dw, respectively. Both Hg and MeHg concentrations increased with an increase of organic matter (OM) content and fine grain fraction. In contrast, Hg accumulation by N. diversicolor was significantly (p 〈 0.05) higher at stations with sandy sediments (mean value: 125 ng g−1 dw) than at stations with muddy sediments (mean value, 80 ng g−1), probably because Hg availability for bioaccumulation at muddy stations was reduced by high OM content of the muddy sediments. MeHg accounted for an average of 0.7% of the total Hg in sediments and 18% of the total Hg in N. diversicolor. Seasonal variations significantly affected Hg concentrations in sediments and MeHg in N. diversicolor. Total Hg concentrations in sediments were significantly (p 〈 0.05) higher in autumn and winter than in spring and summer whereas MeHg concentrations were lowest in winter compared to the other seasons. On the other hand, total Hg concentrations in the worms were lowest in spring whereas MeHg concentrations were significantly (p 〈 0.01) higher in spring and summer than in autumn and winter.
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    Water, air & soil pollution 99 (1997), S. 245-254 
    ISSN: 1573-2932
    Keywords: PCB ; organochlorine pesticide ; sediment ; organic carbon content ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract PCB congeners and organochlorine pesticides (DDT, lindane and HCB) distribution were studied in Lake Orta sediments. The results indicated a contaminated area in the nor-them part of the sub-basin. The observed high levels of organochlorine compounds (OCs) may he explained by the focusing phenomenon, ie. the preferential transport of lighter and smaller particles from the emission sources to this area. The PCBs and DDT values were correlated with the organic carbon content and the heavy metal contamination. The toxicity of the sediment samples was related also to PCB content. PCBs and OCs pollution of Lake Orta was of the same order of magnitude as in Lake Como, which is the most contamined lake in Northern Italy.
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  • 42
    ISSN: 1573-2932
    Keywords: fish farms ; fecal waste ; sediment ; geochemistry ; metabolism ; macrofauna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Benthic observations were carried out at 22 stations in the Western Isles region of the Bay of Fundy on the east coast of Canada to evaluate impacts at salmon aquaculture sites. Eleven sites were located under salmon net-pens and 11 sites (reference or control locations) were at distances 〉 50 m from net-pens. Total S− and redox potential (Eh) in surface sediment and Benthic O2 uptake and CO2 release were sensitive indicators of benthic organic enrichment. High variability between replicate measurements of sediment gas exchange could reflect spatial patchiness in sedimentation of fecal waste and food pellets under fish pens. Biomass of deposit feeders was significantly increased at cage sites but total macrofauna biomass was similar at cage and reference locations. Surface sediment water content, modal grain size, pore water salinity and sulfate, and total biomass of macrofauna were the least sensitive indicators of enrichment.
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  • 43
    ISSN: 1573-2959
    Keywords: risk assessment ; chlorinated compound ; environmental ; marine ; exposure ; aquatic toxicity ; monitoring ; trichloroethylene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This risk assessment on trichloroethylene (TRI) was carried out specifically for the marine environment, according to the methodology laid down in the EU risk assessment Regulation (1488/94) and the Guidance Document of the EU New and Existing Substances Regulation (TGD, 1997). The study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of the "predicted environmental concentrations" (PEC) and the "predicted no effect concentrations" (PNEC) for the marine aquatic environment. In total, 19 studies for fish, 30 studies for invertebrates and 14 studies for algae have been evaluated. Both acute and chronic toxicity studies have been taken into account and the appropriate assessment factors have been used to define a PNEC value of 150 µg/l. Most of the available monitoring data apply to rivers and estuaries and were used to calculate PECs. The most recent data (1991-1995) support a typical PEC of 0.1 µg TRI/l water and a worst case PEC of 3.5 µg TRI/l water. The calculated PEC/PNEC ratios give a safety margin of 40 to 1,500 between the predicted no effect concentration and the exposure concentration. Additional evaluation of environmental fate and bioaccumulation characteristics showed that no concern for food chain accumulation is expected.
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    Environmental monitoring and assessment 59 (1999), S. 225-247 
    ISSN: 1573-2959
    Keywords: cross-cultural ; perceived risk ; risk ; risk analysis ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This study examines perceived risk data from the U.S., China, Japan, and South Korea. These data are then compared with similar results collected from previous studies. Psychometric scaling scores from Burkino Faso (a West African Country), France, Norway, and Hungary have been analyzed and compared with results from our study. The data reveal certain risk events like nuclear weapons, war, and AIDS to have high perceived risks in all countries. These data also show that many of the events have dissimilar perceived risks in different countries. The conclusions also show some countries have higher over all levels of perceive risk (South Korea) while others like the United States display generally lower values.
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    Environmental modeling and assessment 4 (1999), S. 165-178 
    ISSN: 1573-2967
    Keywords: exposure assessment ; ground water contamination ; risk assessment ; spatial variability ; geostatistical analysis ; deterministic modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This paper describes a new methodology for modeling contaminant transport in ground water for (1) better quantifying the magnitude of exposure in a contaminated aquifer, (2) characterizing the spatial and temporal variation of exposure in a heterogeneous aquifer, and (3) providing more tools for characterizing population exposure. This methodology is also applied to a semi-hypothetical case study.
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    Environmental and ecological statistics 3 (1996), S. 81-97 
    ISSN: 1573-3009
    Keywords: gamma distribution ; left censoring ; product limit estimate ; risk assessment ; truncated normal distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A frequent assumption in environmental risk assessment is that the underlying distribution of an analyte concentration is lognormal. However, the distribution of a random variable whose log has a t-distribution has infinite mean. Because of the proximity of the standard normal and t-distribution, this suggests that a distribution such as the gamma or truncated normal, with smaller right tail probabilities, might make a better statistical model for mean estimation than the lognormal. In order to assess the effect of departures from lognormality on lognormal-based statistics, we simulated complete lognormal, truncated normal, and gamma data for various sample sizes and coefficients of variation. In these cases, departures from lognormality were not easily detected with the Shapiro-Wilk test. Various lognormal-based estimates and tests were compared with alternate methods based on the ordinary sample mean and standard error. The examples were also considered in the presence of random left censoring with the mean and standard error of the product limit estimate replacing the ordinary sample mean and standard error. The results suggest that in the estimation of or tests about a mean, if the assumption of lognormality is at all suspect, then lognormal-based approaches may not be as good as the alternative methods.
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    Ecotoxicology 5 (1996), S. 59-81 
    ISSN: 1573-3017
    Keywords: pesticides ; synergism ; risk assessment ; wildlife
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Reviews of pesticide usage survey data and vertebrate wildlife and honeybee poisoning incident schemes in the UK show that there is considerable potential for wildlife to be exposed to combinations of agricultural pesticides. According to the published literature the toxicity of many pesticide combinations is at least additive. In some cases pesticide mixtures, particularly those involving insecticides, have been shown to be synergistic, with reported increases in toxicity of up to 100-fold. However, these effects are species, time and dose dependent and are therefore difficult to predict routinely. It is suggested that risk assessments should routinely take additive toxicity into account and those based on synergism should be targeted at those mixtures for which a further defined increase in toxicity would result in a high-risk classification. In order to support this risk assessment approach there is a need to develop and validate a standard in vivo test in order to confirm the interaction in those cases where additive or synergistic toxicity results in a high-risk classification.
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    Ecotoxicology 5 (1996), S. 139-144 
    ISSN: 1573-3017
    Keywords: ED point ; NOEL ; risk assessment ; pesticides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: The availability and use of ED point and NOEL values in ecotoxicological data submitted to the UK Pesticides Safety Directorate is explored. In first tier data normally submitted for pesticide registration, ED points such as EC/LC/LD50s are commonly available from acute laboratory toxicity studies conducted using birds, small mammals, fish, aquatic invertebrates, plants, honeybees and earthworms. These ED points are subsequently used for hazard classification of the pesticide and in toxicity: exposure ratio (TER) calculations required during the acute risk assessment. Although NOELs can often be available from the same first tier data, they are generally not used. However, NOELs commonly available from higher tier chronic toxicity studies such as chronic fish, Daphnia reproduction and avian reproduction studies, are used in TER calculations to assess chronic risk. The statistical limitations of the NOEL are recognized and the regulatory implications of replacing the NOEL with an alternative ED point are discussed.
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    Ecotoxicology 9 (2000), S. 157-168 
    ISSN: 1573-3017
    Keywords: pyridaben ; water-effect ratio ; WER ; FIFRA ; hazard assessment ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The toxicity and environmental fate of the insecticide-miticide, pyridaben were investigated using both standardized laboratory procedures and outdoor studies with natural water. Outdoor studies provide a more realistic exposure scenario to aquatic organisms and any toxicity is a response to actual exposure concentrations resulting from the natural degradation and dissipation of the chemical. This paper describes the environmental chemistry/fate and aquatic toxicity of pyridaben. The subsequent paper describes the results of the outdoor aquatic toxicity studies and the use of the water-effect ratio in hazard/risk assessment. Environmental fate studies indicate that pyridaben has a low water solubility and high Kd and Koc values, which favors partitioning from water onto soil and sediment. Pyridaben is stable to hydrolysis but has a short photolysis half-life in water (〈30 min) and soil (∼11 d). Furthermore, pyridaben has a short half-life in soil (12 to 14 d) when applied in the field to citrus crops. Laboratory studies with constant 48- to 96-h exposures to pyridaben show it is acutely toxic to fish (Lepomis macrochirus, Pimephales promelas, Oncorhynchus mykiss, Cyprinodon variegatus) and invertebrates (Daphnia magna, Mysidopsis bahia). Invertebrates are more sensitive (lower LC50s) than fish to pyridaben, and most mortalities occur 〈24 h for fish and 〈72 h for invertebrates. Chronic laboratory studies indicate that the MATCs for pyridaben and D. magna, M. bahia and P. promelas were 0.12, 0.15 and 0.39 μg/L, respectively. Acute-to-chronic ratios for pyridaben are low for fish and invertebrates, indicating a low potential for residual activity. Chronic toxicity to aquatic organisms is not an issue after application in the field because exposures tend to be brief.
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    Ecotoxicology 9 (2000), S. 169-177 
    ISSN: 1573-3017
    Keywords: pyridaben ; water-effect ratio ; FIFRA ; hazard assessment ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Outdoor acute aquatic toxicity studies with pyridaben and bluegill sunfish (Lepomis macrochirus) and mysid (Mysidopsis bahia) showed that the 96-h LC50s in site-specific water were significantly greater than in classical laboratory studies. In addition, outdoor acute studies showed that pyridaben degrades rapidly in water, in hours, which supports other laboratory and field studies on the fate of pyridaben in aquatic systems. Chronic toxicity to aquatic organisms is not an issue after application in the field because exposures will be brief. The water-effect ratio (WER) of site-specific to laboratory-water 96-h LC50s for L. macrochirus and M. bahia were 18.5 and 24.5, respectively. The lowest WER was used as an application factor with the laboratory LC50 values of several other aquatic organisms to develop “adjusted” site-specific LC50 values. Comparison of the distribution of “adjusted” LC50 values with a distribution of potential environmental exposure concentrations for pyridaben in water indicates minimal acute risk to aquatic organisms. When only acute laboratory data are available, the WER approach is a relevant and realistic means for determining an application factor and for estimating the aquatic hazard/risk assessment of non-persistent pesticides, because it considers a host of factors that affect bioavailability and subsequent toxicity.
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  • 51
    ISSN: 1573-3017
    Keywords: lead ; waterfawl ; sediment ; toxicity ; mining ; risk assessment ; swans ; ALAD ; protoporphyrin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract For many years, waterfowl have been poisoned by lead after ingesting contaminated sediment in the Coeur d'Alene River Basin, in Idaho. Results of studies on waterfowl experimentally fed this sediment were combined with results from field studies conducted in the Basin to relate sediment lead concentration to injury to waterfowl. The first step in the model estimated exposure as the relation of sediment lead concentration to blood lead concentration in mute swans (Cygnus olor), ingesting 22% sediment in a rice diet. That rate corresponded to the 90th percentile of sediment ingestion estimated from analyses of feces of tundra swans (Olor columbianus) in the Basin. Then, with additional laboratory studies on Canada geese (Branta canadensis) and mallards (Anas platyrhynchos) fed the sediment, we developed the general relation of blood lead to injury in waterfowl. Injury was quantified by blood lead concentrations, ALAD (δ-aminolevulinic acid dehydratase) activity, protoporphyrin concentrations, hemoglobin concentrations, hepatic lead concentrations, and the prevalence of renal nuclear inclusion bodies. Putting the exposure and injury relations together provided a powerful tool for assessing hazards to wildlife in the Basin. The no effect concentration of sediment lead was estimated as 24 mg/kg and the lowest effect level as 530 mg/kg. By combining our exposure equation with data on blood lead concentrations measured in moribund tundra swans in the Basin, we estimated that some mortality would occur at a sediment lead concentration as low as 1800 mg/kg.
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    Natural hazards 5 (1992), S. 279-292 
    ISSN: 1573-0840
    Keywords: Rwanda ; Ruhengeri Prefecture ; Zaire-Nile Divide ; landslides ; flooding ; sediment ; soil loss ; storm rainfall ; return intervals ; erosion control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract In early May 1988, five prefectures in western Rwanda experienced catastrophic levels of precipitation, landslide, and flooding activity that resulted in a severe loss of life, property, and livelihood. Using data from runoff plot and hydrological monitoring stations of the Ruhengeri Resource Analysis and Management Project, the events and circumstances leading to these phenomena are reconstructed. These data show that mass wasting processes were preceded by more than 140 mm of precipitation during 4–7 May, which may have saturated local soils. A small earth tremor on 7 May, (Richter scale of 3) contributed to the onset of the catastrophic debris avalanche, torrent, and earthflow activity that commenced 24 h later. The more than 50 mm of precipitation that fell during 9 May, including a maximum 30 min intensity of 24 mm, resulted in continued surficial soil loss that averaged 34 t/ha on seven cropped, Wischmeier-type runoff plots with biological erosion control contours. The Nyamutera River, which drains the impacted area, delivered 567000 tons of suspended sediment to its mouth between 7 and 13 May. This corresponds to a basin-wide lowering of 12600 t/km2, or more than half of the basin's annual suspended sediment yield. Theoretical distributions of maximum 24 h precipitation events suggest that Nyakinama and other regions in Ruhengeri are particularly prone to similar high volume events, exacerbating an already serious soil loss problem throughout the prefecture. Because contemporary land use practices directly contributed to the severity of the 1988 event, further applied research that identifies technologies capable of reducing soil loss, augmenting soil fertility, and minimizing the impacts of high magnitude and high volume rainfall is greatly needed.
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    Natural hazards 17 (1998), S. 1-15 
    ISSN: 1573-0840
    Keywords: risk assessment ; risk cartography ; volcanic hazard ; GIS ; Vesuvius ; Italy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract This paper assesses the risk to people and property from lava flow hazard in the Vesuvian area of Italy using a Geographical Information System (GIS). The intense urbanisation and dense population near Mt. Vesuvius make the area very hazardous. Due to the large amount of available data, GIS is an essential tool to facilitate risk evaluation and constant monitoring of the zone. This analysis is based mainly on a lava flow hazard map of Mt. Vesuvius, determined from volcanic activity between 1631 and 1944. A land-use zonation map of the area was created in order to show areal distribution of the resources, built-up centres and population. For each of the 17 municipalities in the area, demographic and urban data were entered into the GIS database and linked to each appropriate geographic unit in order to create a set of reference maps at the 1:50 000 scale. The lava flow hazard map was overlain on the land use map, and spatial and numerical information of risk were extracted from the resulting maps.
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    Natural hazards 18 (1998), S. 57-76 
    ISSN: 1573-0840
    Keywords: tsunamis ; historical earthquakes ; risk assessment ; Caribbean Sea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The Caribbean Sea region is well known for its hurricanes, and less known for tsunamis. As part of its responsibilities in hazard assessment and mitigation, the U.S.A. Federal Emergency Management Agency, and the Puerto Rico Civil Defense, funded a pilot study to perform a numerical simulation of the 1918 Puerto Rico tsunami, one of the most deadly in the region. As part of the study a review has been made of the tectonic and tsunamigenic environment around Puerto Rico, the fault parameters for the 1918 event have been estimated, and a numerical simulation has been done using a tsunami propagation and runup model obtained through the Tsunami Inundation Modeling for Exchange (TIME) program. Model results have been compared with the observed runup values all along the west coast of Puerto Rico.
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  • 55
    ISSN: 1572-9729
    Keywords: iron oxyhydroxide ; pyrite ; sediment ; sequential extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A popular sequential extraction procedure (Tessier et al. 1979) designed t o extract metals partitioned in various sediment phases, was evaluated for its selectivity. Amorphous FeOOH, FeS, and FeS2 were added separately to natural lake sediments and sequentially extracted. The selectivity of the sequential procedure for the added solid phases was evaluated by determining the difference in the mass of Fe extracted from treated and control sediments. In the experiments where sulfide minerals were added, total S was measured in the residual solids in order to confirm selectivity of the method. Concentrations of total carbon remaining in the solid phase after each extraction step were also measured to determine the selectivity of the sequential procedure for carbon. The procedure was moderately selective for Fe added as FeOOH; a mean of 77 ± 12% (p 〈 0.05) of the Fe added was extracted in the step designed to reduce Fe-Mn oxyhydroxides. In experiments where FeS was added, a mean of 69 ± 11% (p 〈 0.05) of the Fe added as FeS was extracted in the fraction designed to oxidize sulfides and organic matter. Approximately 25% of the Fe added as FeS may have been extracted prematurely. Although less precise, total S analyses confirmed that much of the FeS was extracted in the oxidation step, yielding 104 ± 87% (p 〈 0.05) of the S added as FeS. The procedure was highly selective for FeS2; 92 ± 14% (p 〈 0.05) of the Fe added as pyrite was extracted in the sulfide extraction step. Extraction of 80 ± 54% (p 〈 0.05) of S added as pyrite confirmed that FeS2 were selectively extracted in the sulfide extraction step. Carbon in the sediments was also selectively extracted in the oxidation step (77 ± 2.4% of total C; p 〈 0.05). The applications and limitations of sequential extraction procedures as limnological research tools are discussed in light of our results.
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    Biodegradation 17 (1992), S. 205-219 
    ISSN: 1572-9729
    Keywords: simultaneous extraction ; sediment ; trace metal partitioning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A simultaneous (SIM) sediment extraction procedure for low carbonate sediments, which partitions sediment-bound trace metals (Fe, Mn, Zn, Cu, and Cd) into easily reducible (associated with Mn oxides), reducible (associated with Fe oxides) and alkaline extracted (bound to organic) metal is presented. The SIM method was compared to the sequential (SEQ) extraction procedure of Tessier et al. (1979). Both methods showed good agreement for the partitioning of Zn and Cd among the easily reducible, reducible and organic components of sediment. Both methods also showed the same general distribution of Mn, Fe and Cu among the three sediment components, however concentrations of metals recovered by the two methods differed; less Mn and Fe and more Cu was recovered from sediments by the SEQ vs. the SIM procedure. Less recovery of Mn is in part attributed to the loss of this metal in the `in between' reagent rinses required in the SEQ procedure. Greater recovery of Cu by the SEQ vs. the SIM method may be due to the pretreatment of sediment with strong reducing agents prior to the step used for liberating organically bound metals. Advantages of a SIM over the SEQ include rapid sample processing time (i.e. the treatment of 40 samples per day vs. 40 samples in three days), plus minimal sample manipulation. Hence, for partitioning metals into easily reducible, reducible and organic sediment components in sediments low in carbonate, we recommend the use of a SIM extraction over that of a SEQ procedure.
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    Biodegradation 22 (1993), S. 81-105 
    ISSN: 1572-9729
    Keywords: estuarine ; oligohaline ; sediment ; sulfate reduction ; sulfur ; sulfide oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Inorganic sulfur turnover was examined in oligohaline (salinity 〈 2 g kg-1) Chesapeake Bay sediments during the summer. Cores incubated for 〈 3 hr exhibited higher sulfate reduction (SR) rates (13–58 mmol m-2 d-1) than those incubated for 3–8 hr (3–8 mmol m-2 d-1). SR rates (determined with35SO 4 2- ) increased with depth over the top few cm to a maximum at 5 cm, just beneath the boundary between brown and black sediment. SR rates decreased below 5 cm, probably due to sulfate limitation (sulfate 〈 25 μM). Kinetic experiments yielded an apparent half-saturating sulfate concentration (Ks) of 34 μM, ≈ 20-fold lower than that determined for sediments from the mesohaline region of the estuary. Sulfate loss from water overlying intact cores, predicted on the basis of measured SR rates, was not observed over a 28-hr incubation period. Reduction of35SO 4 2- during diffusion experiments with intact core segments from 0–4 and 5–9 cm horizons was less than predicted by non-steady state diagenetic models based on35SO 4 2- reduction in whole core injection experiments. The results indicate that net sulfate flux into sediments was an order of magnitude lower than the gross sulfur turnover rate. Solid phase reduced inorganic sulfur concentrations were only 2–3 times less than those in sediments from the mesohaline region of the Bay, despite the fact that oligohaline bottom water sulfate concentrations were 10-fold lower. Our results demonstrate the potential for rapid SR in low salinity estuarine sediments, which are inhabited by sulfate-reducing bacteria with a high affinity for sulfate, and in which sulfide oxidation processes replenish the pore water sulfate pool on a time scale of hours.
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  • 58
    ISSN: 1572-9591
    Keywords: fusion ; inertial confinement ; tritium ; high power density ; advanced fuels ; monte carlo ; particle transport ; pool-type reactor ; target designs ; liquid metals ; lithium ; radiation damage ; environmental effects ; safety considerations ; radioactive releases ; risk assessment ; neutron source ; first wall
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A low-tritium-inventory, high-power-density, pool-type chamber approach to inertial confinement fusion is introduced. The concept uses target designs with internal tritium and3He breeding, eliminating the need for a lithium-breeding blanket. The fraction of the fusion energy carried out by neutrons is estimated as 10%, compared with 70% in a typical D-T system, and the neutron spectrum is softer. Liquid metals other than lithium that are less chemically reactive, such as lead, can be used for first-wall protection. The reduced neutron component and the elimination of the need for a thick lithium blanket for tritium breeding lead to higher power densities and more compact chamber designs. The radiation damage at the first structural wall is reduced, leading to potentially longer wall lifetimes. A significant environmental advantage in terms of reduced radioactive release risks under operational and accident conditions is identified, primarily due to the one to two orders of magnitude reduction in the tritium inventories compared with D-T-based systems.
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    Water, air & soil pollution 85 (1995), S. 2515-2520 
    ISSN: 1573-2932
    Keywords: Regionalization ; critical loads ; forest ; uncertainty ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The steady-state model PROFILE was used to perform Monte Carlo simulations of critical loads of acidity and exceedances of forest soils for 128 sites in the province of Scania, southern Sweden. Statistical tests showed that 100 sites had normal distributed critical loads and exceedances and that the variance of these parameters was statistically equal for all sites. Pooled estimates of the standard deviation was 0.19 and 0.31 kmolc ha−1 yr−1 for the critical loads and exceedances, respectively. Introduction of uncertainties, expressed as confidence intervals, in the cumulative distribution function for critical loads showed that overlaps between percentiles were substantial. The 5%-ile was systematically equal to the 57%-ile using a 67% confidence interval and equal to the 87%-ile when a 95% confidence level was chosen. The overlaps of percentiles cause a reduction of acidic deposition according to the mean value of the 5%-ile to protect only 68% of the ecosystem area with an 84% probability and not a guaranteed protection of 95% as if uncertainties did not exist. Thus, uncertainties make it possible to advocate reductions to levels of deposition below the 5%-tile of critical loads.
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  • 60
    ISSN: 1573-2932
    Keywords: reservoir of heated water ; contamination ; cadmium ; copper ; nickel ; sediment ; water ; enrichment factor ; geoaccumulation index ; contamination factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In this paper, the contamination degree of the Rybnik Reservoir with cadmium, copper andnickel was analyzed. Quality of the water from the reservoir was determined by drawingcomparisons between the metal content in the water and both the officially permitted levels(contamination factor) and levels of metals occurring in the water of non-contaminated areas(enrichment factor). Contamination of bottom sediment with chosen metals was analyzed withreference to the metal content in mudstone (geoaccumulation index, enrichment factor,contamination factor). Trends towards changing the metal content in the bottom sediment wasanalyzed by determining the enrichment factor of the surface layer of the bottom sediments inrelation to a deeper layer. Enrichment of the bottom sediments with metals coming from the waterwas also determined.
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    Water, air & soil pollution 99 (1997), S. 515-522 
    ISSN: 1573-2932
    Keywords: sediment ; dredging ; trace metal ; nutrients ; bacteria ; reoxidation ; remobilization ; microbial processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Polluted sediments are periodically subjected to resuspension processes resulting from natural events (e.g. storms, strong waves) as well as from anthropogenically induced activities (e.g. dredging). The main part of the resuspended material is initially in an anoxic state and will be reoxidized more or less quickly in the oxic water column. In laboratory experiments reflecting, as far as possible, natural conditions (e.g. constant pH) the release of Cd, Cu and Zn during this reoxidation phase was investigated. Up to 2% of the particulate bound heavy metals were remobilized from the sediments. In addition the evolution of the concentrations of the anions PO4, SO4, NO3 and NH4 were measured to examine the influence of microbial processes on the release of trace elements. Cell counts and microbial activity of certain micro-organisms during the release processes were also investigated. The investigations illustrated that biological activity has a significant effect on release. In all sediment samples the release of cadmium was delayed in comparison with the other elements even in sediments from different river systems. The influence of different microbial processes on this divergent behavior was examined. The significance of dredging activities to the remobilization processes during reoxidation of anoxic sediments in the Elbe River is discussed.
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  • 62
    ISSN: 1573-2932
    Keywords: Diagenesis ; resuspension ; sediment ; pore-water ; marine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This paper presents the results of a study on nutrient exchange at the sediment-water interface which is caused by early diagenesis and resuspension of bottom sediments. The research was carried out on anoxic silty-clay sediment cores collected south of the Po river delta (Northern Adriatic Sea, Italy) in late summer. The early diagenetic processes were investigated by means of the integrated study of pore-water chemistry and solid phase composition. Exchange at the sediment-water interface was studied by comparing the fluxes measured in incubated cores with the fluxes calculated by modelling pore-water profiles. Nutrient exchange during resuspension was analysed by simulating a storm event in the laboratory. The high production of nutrients near the sediment-water interface is mainly caused by the anoxic degradation of organic matter and the successive reductions of Mn and Fe-oxyhydroxides and, to a lesser extent, of sulphate. The oxic degradation of organic matter occurs only at the sediment-water interface. In the incubation experiment the increases of phosphate, ammonia, nitrate, silica, and Fe in bottom waters were measured. The comparison between calculated and measured fluxes showed that: a) the fluxes are mainly controlled by molecular diffusion; b) phosphate and Fe sink because of the Fe-oxyhydroxide precipitation and c) nitrification process influences the ammonia and nitrate fluxes. Resuspension caused the release of: a) phosphate through surficial desorption and authigenic apatite dissolution; b) ammonia by means of the oxic degradation of organic matter; and c) dissolved silica generated by biogenic silica dissolution. Resuspension also caused a weak removal of Fe. The more oxic conditions following resuspension favoured the formation of a Fe-oxyhydroxide film at the sediment-water interface which inhibited the phosphate fluxes from sediments to the water column.
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  • 63
    ISSN: 1573-2932
    Keywords: Aquaculture ; aggregation ; flocculation ; grain size ; sediment ; trace metal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Grain size is the most basic of classification criteria for sediments. The size distribution of a given sediment records the physical transport processes involved in its formation. By using precise grain size analysis and the model of Kranck et al. (1996a,b), it is possible to break down a sediment into the three major components from which it was formed: material deposited as flocs, material deposited as single grains from suspension, and material carried under higher energy conditions. With this method, both the amount of material deposited in a flocculated state and the maximum size, or floc limit, of the particles composing the floc can be determined. Changes in floc limit indicate changes in the aggregation dynamics of the system. As most trace metals and many other contaminants associate closely with the fine particle fraction of sediments, it is important to determine both the areal distribution and reworking history of the floc settled portion of a sediment. This paper discusses the application of the method to coastal inlets in Atlantic Canada and examines the relationship between proportion of floc-settled material and trace metal concentrations. Disaggregated inorganic grain size distributions are also used to illustrate changes in the aggregation dynamics in areas of intense aquaculture.
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    Water, air & soil pollution 99 (1997), S. 717-725 
    ISSN: 1573-2932
    Keywords: chlorinated pesticides ; PCB ; sediment ; Himalayan lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract PCBs and organochlorine pesticides were determined in water, sediment and zooplankton of two Himalayan lakes, located at different altitudes and connected to each other in such a way that Superior Lake acts as a sedimentation basin for Inferior Lake. Surficial sediments of both lakes show PCB contamination comparable to lakes of industrialised areas. Biota appear to be the main machanism responsible for micropollutant burial in the sediments of Inferior Lake, whereas inorganic particles are more relevant in Superior Lake. Physical and chemical properties of individual chemicals, particularly Henry's law constant and Kow values, seem to regulate distribution in different environmental compartments.
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  • 65
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    Water, air & soil pollution 99 (1997), S. 81-88 
    ISSN: 1573-2932
    Keywords: channel ; bend ; sediment ; size ; gradation ; sorting ; bed ; topography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Variations of sediment size and its gradation of the bed surface laver in a channel bend with nonuniform sediment are investigated experimentally. Four groups of sediment with the same initial median diameter (D o ) but different initial size gradation (σ o ) have been used for experiments which were run until the equilibrium bed topography was achieved. Analyses of experimental data have yielded the following results: (1) The time of equilibrium for bed evolution decreases asσ o increases: (2) the median size of sediment (D) for a given section in the bend increases with increasing distance from the inner bank towards the outer bank, and it also increases with increasingσ o ; (3) the value of D/D o along the inner bank decreases with increasingσ o , and it also shows a gradual decrease in the upper half of the bend and a slight recovery in the lower half, and (5) the transverse variation ofσ value exhibits a general trend increasing from the inner bank towards the outer bank.
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  • 66
    ISSN: 1573-2932
    Keywords: phosphorus ; P flux ; microbial activity ; redox ; simulation ; Lake Kinneret ; sediment ; accumulative P release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Different factors which interactively control the flux of soluble reactive phosphorus (SRP) at the sediment water irterface (SWI) of Lake Kinneret were studied seasonally. The influence of pH, Eh and microbial activity on SRP flux at the SWI was investigated by manipulating the conditions in the overlying water of intact sediment cores. The calculated diffusive SRP flux out of the sediment was lower in cores sampled during winter and spring than during the period of amixis. Potential SRP release, as measured in the absence of microbial activity, was strongly enhanced upon the transition from oxic to anoxic conditions indicating P release from iron(III)-bound phosphorus. In spring and summer cores, an enhanced SRP flux from sediments at pH 7 in comparison to pH 8 indicated P release from carbonate-bound P which sedimented previously as result of high pH values during the algal spring bloom. Microbial uptake at the SWI was the most important sink for SRP and no net-flux occured under oxic conditions. The higher net-flux of P under anoxic conditions was linked to carbon limitation ofthe bacteria at the SWI.
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  • 67
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    Water, air & soil pollution 99 (1997), S. 477-486 
    ISSN: 1573-2932
    Keywords: sediment ; nitrogen ; phosphorus ; organic matter ; cluster analysis ; Gulf of Finland ; estuaries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Dry weight (DW), ignition loss (IL) and concentrations of total nitrogen (TN) and total phosphorus (TP) of the sediment surface layer (0 to 10 cm, 1 cm slices) were analyzed from 20 sites in the eastern Gulf of Finland. The distance of the sampling sites from the mouth of the River Neva explained the nutrient concentrations of the sediments well, while the effect of water depth was negligible. The increase of TN and the decrease of TP along the transect from the river mouth towards the open Gulf were caused by the diminishing share of allochthonous material supplied from the River Neva. The mean TN concentration of the different accumulation areas was about 40 % higher in the sediment surface than in the deeper layer (9 to 10 cm). The corresponding difference for TP varied from 53 to 56 %. The results suggest considerable netflux of nutrients from sediment to water. The net sediment accumulation of nutrients were estimated as 6.0 g m−2 a−1 of N and 1.7 g m−2 a−1 of P corresponding 22 000 t a− of N and 6 100 t a−1 of P for the whole eastern Gulf.
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  • 68
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    Water, air & soil pollution 99 (1997), S. 515-522 
    ISSN: 1573-2932
    Keywords: sediment ; dredging ; trace metal ; nutrients ; bacteria ; reoxidation ; remobilization ; microbial processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Polluted sediments are periodically subjected to resuspension processes resulting from natural events (e.g. storms, strong waves) as well as from anthropogenically induced activities (e.g. dredging). The main part of the resuspended material is initially in an anoxic state and will be reoxidized more or less quickly in the oxic water column. In laboratory experiments reflecting, as far as possible, natural conditions (e.g. constant pH) the release of Cd, Cu and Zn during this reoxidation phase was investigated. Up to 2% of the particulate bound heavy metals were remobilized from the sediments. In addition the evolution of the concentrations of the anions PO4, SO4, NO3 and NH4 were measured to examine the influence of microbial processes on the release of trace elements. Cell counts and microbial activity of certain micro-organisms during the release processes were also investigated. The investigations illustrated that biological activity has a significant effect on release. In all sediment samples the release of cadmium was delayed in comparison with the other elements even in sediments from different river systems. The influence of different microbial processes on this divergent behavior was examined. The significance of dredging activities to the remobilization processes during reoxidation of anoxic sediments in the Elbe River is discussed.
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  • 69
    ISSN: 1573-2932
    Keywords: Diagenesis ; resuspension ; sediment ; pore-water ; marine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This paper presents the results of a study on nutrient exchange at the sediment-water interface which is caused by early diagenesis and resuspension of bottom sediments. The research was carried out on anoxic silty-clay sediment cores collected south of the Po river delta (Northern Adriatic Sea, Italy) in late summer. The early diagenetic processes were investigated by means of the integrated study of pore-water chemistry and solid phase composition. Exchange at the sediment-water interface was studied by comparing the fluxes measured in incubated cores with the fluxes calculated by modelling pore-water profiles. Nutrient exchange during resuspension was analysed by simulating a storm event in the laboratory. The high production of nutrients near the sediment-water interface is mainly caused by the anoxic degradation of organic matter and the successive reductions of Mn and Fe-oxyhydroxides and, to a lesser extent, of sulphate. The oxic degradation of organic matter occurs only at the sediment-water interface. In the incubation experiment the increases of phosphate, ammonia, nitrate, silica, and Fe in bottom waters were measured. The comparison between calculated and measured fluxes showed that: a) the fluxes are mainly controlled by molecular diffusion; b) phosphate and Fe sink because of the Fe-oxyhydroxide precipitation and nitrification process influences the ammonia and nitrate fluxes. Resuspension caused the release of: a) phosphate through surficial desorption and authigenic apatite dissolution; b) ammonia by means of the oxic degradation of organic matter; and c) dissolved silica generated by biogenic silica dissolution. Resuspension also caused a weak removal of Fe. The more oxic conditions following resuspension favoured the formation of a Fe-oxyhydroxide film at the sediment-water interface which inhibited the phosphate fluxes from sediments to the water column.
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  • 70
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    Environmental monitoring and assessment 50 (1998), S. 249-254 
    ISSN: 1573-2959
    Keywords: lacustrine ; metal accumulation ; riverine ; sediment ; snail ; tissue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Cadmium, chromium, iron, manganese, nickel, lead and zinc concentrations were determined in sediment and body tissues, viz. digestive gland, mantle and shell, of the freshwater snail, Angulyagra oxytropis (Benson) (Gastropoda : Viviparidae), from River Barak and one of its floodplain lakes in Cachar district, Assam State, Northeastern India. The concentrations of all the metals except iron are significantly higher in the lake sediment. When compared to their riverine counterparts, the lacustrine snails contain higher concentrations of cadmium, chromium and iron in their mantle; nickel and zinc in digestive gland; manganese in both digestive gland and mantle; and lead in all the three tissues examined. The accumulation patterns of most of the metals varied considerably between the two sites. The implications of these findings in storage, sequestration and detoxification of metals by this animal are discussed. The study also indicates that A. oxytropis may be a potential biological indicator of metal contamination in freshwater ecosystems.
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  • 71
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    Environmental monitoring and assessment 64 (2000), S. 409-419 
    ISSN: 1573-2959
    Keywords: monitoring ; assessment ; water ; sediment ; bioaccumulation ; toxicity ; pesticides ; mercury ; PCB
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The San Francisco Estuary Regional Monitoring Program for Trace Substances (RMP) began in 1993 and is sponsored by 74 local, state, and federal agencies and companies through their discharge or Bay use permits. The RMP monitors water, sediment, toxicity, and bivalve bioaccumulation at 25 sites in the Bay that are considered to represent "background" conditions. Several major environmental issues have been identified by the RMP. Polychlorinated biphenyls and mercury were often above water quality guidelines, and often occurred in fish tissues above U.S. Environmental Protection Agency (U.S. EPA) screening values. Concentrations do not appear to be decreasing, suggesting continuing inputs. Episodes of aquatic toxicity often occurred following runoff events that transport contaminants into the Bay from urbanized and agricultural portions of the watershed. Sediment toxicity occurred throughout the Bay, and has been correlated with concentrations of specific contaminants (chlordanes, polynuclear aromatic hydrocarbons) at some locations; mixtures of contaminants were probably also important. Since the RMP does not monitor all ecosystem components, assessments of the overall condition of the Bay cannot be made. However, in terms of contamination, the RMP samples suggest that the South Bay, and North Bay sites are moderately contaminated.
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  • 72
    ISSN: 1573-3017
    Keywords: jet fuel ; microcosm ; multivariate statistics ; nonmetric clustering ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Turbine fuels are often the only aviation fuel available in most of the world. Turbine fuels consist of numerous constituents with varying water solubilities, volatilities and toxicities. This study investigates the toxicity of the water soluble fraction (WSF) of JP-4 using the Standard Aquatic Microcosm (SAM). Multivariate analysis of the complex data, including the relatively new method of nonmetric clustering, was used and compared to more traditional analyses. Particular emphasis is placed on ecosystem dynamics in multivariate space. The WSF is prepared by vigorously mixing the fuel and the SAM microcosm media in a separatory funnel. The water phase, which contains the water-soluble fraction of JP-4 is then collected. The SAM experiment was conducted using concentrations of 0.0, 1.5 and 15% WSF. The WSF is added on day 7 of the experiments by removing 450 ml from each microcosm including the controls, then adding the appropriate amount of toxicant solution and finally bringing the final volume to 3 L with microcosm media. Analysis of the WSF was performed by purge and trap gas chromatography. The organic constituents of the WSF were not recoverable from the water column within several days of the addition of the toxicant. However, the impact of the WSF on the microcosm was apparent. In the highest initial concentration treatment group an algal bloom ensued, generated by the apparent toxicity of the WSF of JP-4 to the daphnids. As the daphnid populations recovered the algal populations decreased to control values. Multivariate methods clearly demonstrated this initial impact along with an additional oscillation seperating the four treatment groups in the latter segment of the experiment. Apparent recovery may be an artifact of the projections used to describe the multivariate data. The variables that were most important in distinguishing the four groups shifted during the course of the 63 day experiment. Even this simple microcosm exhibited a variety of dynamics, with implications for biomonitoring schemes and ecological risk assessments.
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  • 73
    ISSN: 1573-3017
    Keywords: ambient toxicity ; community diversity ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The goals of this study were to assess the results of a suite of sediment and water column bioassays in the framework of a toxicological risk ranking model and evaluate correlations of model output with fish community metrics. The test sites were located in four tributaries of Chesapeake Bay that are impacted on by industrial, urban and agricultural land use (Curtis Creek, Rock Creek, Fishing Bay and Wicomico River). The mortality, reproduction and growth rates in the water column assays indicated low-level chemical contamination impacts in Curtis Creek and Rock Creek. The results from the Wicomico River and Fishing Bay did not indicate contaminant impacts, but some borderline effects were seen. The sediment bioassays demonstrated greater toxicological responses than the water column assays. The sediments in the Curtis Creek and Rock Creek sites were contaminated with heavy metals and PAHs. The heavy metal concentrations were an order of magnitude lower in the Fishing Bay sediments and below detection in the Wicomico River sediments, except for zinc. The acid-volatile sulphides:simultaneously extractable metals (AVS:SEM) ratios were below 1 in all cases. All four systems had detectable petroleum hydrocarbon contamination. Organic contaminants were below detection for all analyses in the Wicomico River and Fishing Bay samples. The risk ranking model ranked Curtis Creek as the most toxicologically impacted site, followed by Rock Creek, Fishing Bay and Wicomico River, which were essentially equal. The diversity index for fish communities sampled by bottom trawl was significantly correlated with the toxicological risk scores for sediment. The toxicological results indicate sediment contamination effects on the deep water fish community in Curtis Creek and indicate that contaminant impacts are not likely to be a contributing factor to disturbed fish communities in Fishing Bay
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  • 74
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    Ecotoxicology 7 (1998), S. 279-290 
    ISSN: 1573-3017
    Keywords: microcosm ; Raphidocelis subcapitata ; Lemna minor ; Hyalella azteca ; Chironomus tentans ; Daphnia magna ; Simocephalus vetulus ; sediment ; copper
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A new laboratory freshwater/sediment microcosm test is proposed. This 2-L microcosm includes synthetic water, sediment composed of quartz sand, cellulose and fish food flakes (TetraMin®), pelagic organisms (microalgae, duckweeds, cladocerans) and benthic organisms (amphipods, chironomids). We conducted four experiments to determine conditions suitable for the development of organisms for a 4-week duration. The sensitivity of the system was then studied with a copper-spiked sediment. A TetraMin® dose of 0.4 g for 260 g sediment was found optimal to allow growth and emergence of chironomid larvae without bacterial contamination due to excess organic matter. The test with copper sulfate led to a range of effects. For concentrations higher than 10 ppm, systems were severely impaired (growth inhibition of algae and duckweeds 〉50%, 100% mortality within a few days for cladocerans, mortality 〉45% within 15 days for amphipods, 80% mortality within 15 days and no emergence for chironomids). At 10 ppm, a shift of the algal peak was observed, duckweed growth was reduced by 39%, partial mortality but no reduced reproduction was found for Daphnia magna whereas Simocephalus vetulus survived only after reinoculation on day 10. Amphipods also survived but were smaller. For chironomids, partial mortality was observed as soon as day 22 and emergence was inhibited by 50% but growth was not affected.
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  • 75
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    Water, air & soil pollution 97 (1997), S. 323-340 
    ISSN: 1573-2932
    Keywords: carbon ; management ; sediment ; selenium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The distribution of selenium in sediment in Benton Lake is mainly controlled by the location of the dissolved selenium inputs. Selenium concentrations in sediment decrease along flow paths downgradient within the wetland system. Construction in 1961 of a pump station to increase water supply and dikes to facilitate water management, along with current water management, has increased the rate of selenium accumulation in sediments as compared to the pre-1961 natural lake. Agricultural practices (alternate crop/fallow rotation) in the non-irrigated farm land of the seleniferous Benton Lake basin also have increased selenium loading to Benton Lake. Carbon content is an important factor affecting selenium distribution in sediment but this relationship is greatly affected by dissolved selenium inputs. Amelioration of selenium contamination in Benton Lake will require a combination of land and water management modifications. Within the wetland system, minimizing the duration of inlet-perennial ponds would minimize selenium accumulation and increase the life of the refuge.
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  • 76
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    Water, air & soil pollution 99 (1997), S. 275-282 
    ISSN: 1573-2932
    Keywords: selenium ; sediment ; estuaries ; sequential extraction ; redox potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Selenium (Se) is a contaminant of concern in environments affected by discharges from smelting and coal-burning industries. Experiments have been performed to investigate the phase associations of selenium in contaminated sediments under a range of controlled redox conditions. In this study, Se sediment associations were examined using the BCR sequential extraction technique after stabilisation at different redox states. It was shown that although most of the sediment-bound Se is associated with the operationally-defined "organic/sulfide" fraction, as the measured redox potential of the system is increased, more Se moves into the "exchangeable" and "iron/manganese oxyhydroxide" fractions. In these fractions, contaminants can be expected to be more bioavailable. As the mass of Se absorbed to sediments is typically at least an order of magnitude higher than the mass dissolved in porewaters, significant Se exposure may result from oxidative shifts in Se associations.
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  • 77
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    Water, air & soil pollution 99 (1997), S. 315-323 
    ISSN: 1573-2932
    Keywords: lake ; sediment ; carbon ; nitrogen ; stable isotope ; fractionation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Stable isotope composition of carbon and nitrogen in the sediment and pore water of a eutrophic freshwater lake was studied. Based on changes in the δ13C and δ15N values of dissolved components and sediment fraction, possible processes involved in the decomposition of sedimentary organic matter are outlined. The relative importance of acetate fermentation and CO2 reduction was estimated using known mathematical models, and ammonia assimilation by methanogenic bacteria is hypothesised to be the main process governing the isotope fractionation of dissolved nitrogen in pore water.
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  • 78
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    Water, air & soil pollution 97 (1997), S. 323-340 
    ISSN: 1573-2932
    Keywords: carbon ; management ; sediment ; selenium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The distribution of selenium in sediment in Benton Lake is mainly controlled by the location of the dissolved selenium inputs. Selenium concentrations in sediment decrease along flow paths downgradient within the wetland system. Construction in 1961 of a pump station to increase water supply and dikes to facilitate water management, along with current water management, has increased the rate of selenium accumulation in sediments as compared to the pre–1961 natural lake. Agricultural practices (alternate crop/fallow rotation) in the non-irrigated farm land of the seleniferous Benton Lake basin also have increased selenium loading to Benton Lake. Carbon content is an important factor affecting selenium distribution in sediment but this relationship is greatly affected by dissolved selenium inputs. Amelioration of selenium contamination in Benton Lake will require a combination of land and water management modifications. Within the wetland system, minimizing the duration of inlet-perennial ponds would minimize selenium accumulation and increase the life of the refuge.
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  • 79
    ISSN: 1573-2932
    Keywords: environment ; industrial pollution ; lake ; magnetic measurements ; metals ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Mineral magnetic measurements have been made on three sediment cores from Lake Donghu, Wuhan, which reveal evidence for changes in magnetic properties of the sediments. It is suggested that the recent lake sediment profiles contain deposited magnetic minerals and atmospherically derived fly ash from industrial processes. In the cores, the record of ‘magnetite’ deposition shows that the environment of the lake has been affected by heavy industrial processes in intensity and range beginning from the 1950's onwards and remaining relatively uniform in the last decades. In Core I the record of ‘hematite’ deposition parallels that for influence of urban waste water input.
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  • 80
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    Water, air & soil pollution 99 (1997), S. 717-725 
    ISSN: 1573-2932
    Keywords: chlorinated pesticides ; PCB ; sediment ; Himalayan lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract PCBs and organochlorine pesticides were determined in water, sediment and zooplankton of two Himalayan lakes, located at different altitudes and connected to each other in such a way that Superior Lake acts as a sedimentation basin for Inferior Lake. Surficial sediments of both lakes show PCB contamination comparable to lakes of industrialised areas. Biota appear to be the main machanism responsible for micropollutant burial in the sediments of Inferior Lake, whereas inorganic particles are more relevant in Superior Lake. Physical and chemical properties of individual chemicals, particularly Henry's law constant and Kow values, seem to regulate distribution in different environmental compartments.
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  • 81
    ISSN: 1573-2959
    Keywords: benthic community tolerance ; sediment ; sediment quality triad ; toxicity ; toxic units
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract We evaluated the toxic-units model developed by Wildhaber and Schmitt (1996) as a predictor of indices of mean tolerance to pollution (i.e., Lenat, 1993; Hilsenhoff, 1987) and other benthic community indices from Great Lakes sediments containing complex mixtures of environmental contaminants (e.g., polychlorinated biphenyls – PCBs, polycyclic aromatic hydrocarbons – PAHs, pesticides, chlorinated dioxins, and metals). Sediment toxic units were defined as the ratio of the estimated pore-water concentration of a contaminant to its chronic toxicity as estimated by U.S. Environmental Protection Agency Ambient Water Quality Criteria (AWQC) or other applicable standard. The total hazard of a sediment to aquatic life was assessed by summing toxic units for all contaminants quantified. Among the benthic community metrics evaluated, total toxic units were most closely correlated with Lenat's (1993) and Hilsenhoff's (1987) indices of community tolerance (T L and T H , respectively); toxic units accounted for 42% T L and 53% T H of variability in community tolerance as measured by Ponar grabs. In contrast, taxonomic richness and Shannon-Wiener diversity were not correlated (P 〉 0.05) with toxic units. Substitution of order- or family-level identifications for lowest possible (mostly genus- or species-) level identifications in the calculation of T L and T H indices weakened the relationships with toxic units. Tolerance values based on order- and family-level identifications of benthos for artificial substrate samples were more strongly correlated with toxic units than tolerance values for benthos from Ponar grabs. The ability of the toxic-units model to predict the other two components (i.e., laboratory-measured sediment toxicity and benthic community composition) of the Sediment Quality Triad (SQT) may obviate the need for the SQT in some situations.
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  • 82
    ISSN: 1573-2959
    Keywords: risk assessment ; chlorinated compound ; environmental ; marine ; exposure ; aquatic toxicity ; monitoring ; chloroform
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This risk assessment on chloroform was carried out specifically for the marine environment, according to the methodology laid down in the EU risk assessment Regulation (1488/94) and the Guidance Document of the EU New and Existing Substances Regulation (TGD, 1997). The study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of the "predicted environmental concentrations" (PEC) and the "predicted no effect concentrations" (PNEC) for the marine aquatic environment. In total, 23 studies for fish, 17 studies for invertebrates and 10 studies for algae have been evaluated. Both acute and chronic toxicity studies have been taken into account and the appropriate assessment factors have been used to define a typical PNEC value of 72 µg/l. Due to limitations of the studies evaluated, a worst PNEC of 1 µg/l could also be used. Most of the available monitoring data apply to rivers and estuaries and were used to calculate PECs. The most recent data (1991-1995) support a typical PEC of 0.2 µg chloroform per litre of water and a worst case PEC of 5 to 11.5 µg chloroform per litre of water. The calculated PEC/PNEC ratios give a safety margin of 6 to 360 between the predicted no effect concentration and the exposure concentrations. A worst case ratio, however, points to a potential risk for sensitive species. Refinement of the assessment is necessary by looking for more data. Additional evaluation of environmental fate and bioaccumulation characteristics showed that no concern is expected for food chain accumulation.
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  • 83
    ISSN: 1573-2959
    Keywords: risk assessment ; chlorinated compound ; environmental ; marine ; exposure ; aquatic toxicity ; monitoring ; tetrachloroethylene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This risk assessment on tetrachloroethylene (PER) was carried out specifically for the marine environment, according to the methodology laid down in the EU risk assessment Regulation (1488/94) and the Guidance Document of the EU New and Existing Substances Regulation (TGD, 1997). The study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of the "predicted environmental concentrations" (PEC) and the "predicted no effect concentrations" (PNEC) for the marine aquatic environment. In total, 18 studies for fish, 13 studies for invertebrates and 8 studies for algae have been evaluated. Both acute and chronic toxicity studies have been taken into account and the appropriate assessment factors have been used to define a PNEC value of 51 µg/l. Most of the available monitoring data apply to rivers and estuary waters and were used to calculate PECs. The most recent data (1991-1995) support a typical PEC of 0.2 µg PER/l water and a worst case PEC of 2.5 µg PER/l water. The calculated PEC/PNEC ratios give a safety margin of 20 to 250 between the predicted no effect concentration and the exposure concentration. Additional evaluation of environmental fate and bioaccumulation characteristics showed that no concern is expected for food chain accumulation.
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  • 84
    ISSN: 1573-2959
    Keywords: heavy metal ; sea water ; sediment ; spectroscopy ; voltammetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In this present work the distribution of heavy metals in sea water and sediments of the Salerno Gulf is measured. The elements determined were Cu, Pb, Cd, Zn and Hg, employing, as instrumental techniques, either differential pulse anodic stripping voltammetry (DPASV) or graphite furnace atomic absorption spectroscopy (GFAAS). A comparison of the results of the two analytical techniques is also made. Mercury determination was carried out employing the cold vapour atomic absorption spectroscopy (CVAAS) technique, with SnCl2 as the reducing agent. The sample digestion was performed by a new procedure using concentrated suprapure H2SO4–K2Cr2O7 mixture. The accuracy and precision of the analytical procedure were evaluated employing Sea Water BCR-CRM 403 and Estuarine Sediment BCR-CRM 277 as reference materials. Accuracy, expressed as relative error e and precision, expressed as relative standard deviation sr, were in order of 2 to 5%. For both matrices, the detection limits, for all the elements, were in the range μg g-1 to ng g-1.
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  • 85
    ISSN: 1573-2959
    Keywords: atmospheric transport models ; persistent organicpollutants ; pesticides ; plant protection products ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In the evaluation of potentially adverse effects oforganic chemicals such as pesticides on theenvironment the atmosphere may play an important role.After its release to the atmosphere the chemical willbe transported/dispersed in the atmosphere and finallyit will be removed either by atmospheric-chemicaldestruction or by deposition to the underlying soil orsurface water. In a risk assessment decision supportsystem both ambient concentrations and depositionfluxes must be known to evaluate the risk of directexposure (inhalation) or the risk of soil and watercontamination caused by deposition. This paperdiscusses the use of atmospheric dispersion models insuch risk assessment decision support systems.
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  • 86
    ISSN: 1573-2959
    Keywords: modeling ; New York City ; risk assessment ; watershed monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The International Life SciencesInstitute (ILSI) Risk Science Institute (RSI) convenedan expert panel of scientists to developrecommendations for a comprehensive monitoring programfor the Croton and Catskill/Delaware watersheds, whichprovide drinking water to New York City's residents. This effort was conducted as part of efforts topreserve and enhance the quality of New York City'sreservoir system through a watershed protectionprogram. The panel developed recommendations for astrategic framework on which to construct a monitoringprogram. As part of this activity, the paneldetermined whether existing monitoring activities weredeficient and, where activities were deficient, thepanel developed recommendations for additionalinformation that should be collected.The panel recommended the development and use of anintegrated approach to watershed monitoring, whichdraws on modeling, risk-based planning and analysis,statistical sampling and design, and basic compliancemonitoring. The approach should be designed toprovide an assessment of natural and anthropogenicsources of stress to the system as well as anassessment of water quality trends in response tostresses acting in concert, both over the long termand over the five-year New York City Memorandum ofAgreement (MOA) assessment time frame. It should alsoprovide an assessment of the human health andenvironmental risks posed by a variety of stressors,and the impact of management actions implemented toameliorate stressors.
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  • 87
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    Environmental monitoring and assessment 63 (2000), S. 329-339 
    ISSN: 1573-2959
    Keywords: bioavailable ; lead ; sediment ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This study determined the spatial distribution of soiland of sediment-associated lead in Iqaluit, Nunavut.Samples were collected from the following areas:outside the built-up area of the town to reflectbackground concentrations; known or potential pointsources of lead, such as the Upper Base, the SylviaGrinnell Dump and the Metal Dump (North 40); andresidential and commercial areas of Iqaluit and Apex,a satellite community. In the laboratory, the 〈63 μm sample fraction was analyzed for total lead andbioavailable lead, estimated by non-residual acidextractable lead content. The research findings revealthat elevated levels of bioavailable lead are presentin the study area. Total lead concentrations generallydo not exceed environmental guidelines. However, leadconcentrations in the Sylvia Grinnell Dump, and Apexand Iqaluit grid areas exceed health-based guidelines.The research concludes that there is not a serioushealth hazard posed by lead levels in the soil andsediment in the study area. However, severalenvironmental (elevated lead levels, bioavailableforms of lead and bare soil surfaces) and behaviouralfactors (vigorous and unsupervised play outside) maycreate a risk of lead exposure.
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  • 88
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    Environmental and ecological statistics 3 (1996), S. 189-206 
    ISSN: 1573-3009
    Keywords: Carcinogenesis models ; formaldehyde ; risk assessment ; rodent ; serial sacrifice experiments ; squamous cell carcinoma ; squamous metaplasia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The model of Dewanji and Kalbfleisch for the estimation of time to tumour onset from a serial-sacrifice experiment is extended to include a marker state prior to the onset of the tumour. There are two versions of the model, one where a tumour is allowed to develop without the onset of marker, the other where a tumour develops after the marker but in which the marker later becomes unobservable.
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  • 89
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    Environmental and ecological statistics 7 (2000), S. 77-91 
    ISSN: 1573-3009
    Keywords: acid deposition ; Bayesian inference ; Dirichlet distribution ; fish response ; Gibbs sampler ; lake eutrophication ; PCB ; risk assessment ; salmonid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In environmental management, we often have to deal with binary response variables whose outcome dictates the course of action. This paper introduces a nonparametric Bayesian binary regression model with a single predictor variable that is more flexible than the commonly used logistic or probit models. Due to the Bayesian feature, the model can be easily used to combine observed data with our knowledge of the subject to produce site-specific results. By using three examples, this paper shows the potential application of the model in the environmental management, and its advantages in terms of flexibility in model specification, robustness to outliers, and realistic interpretation of data.
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  • 90
    ISSN: 1573-3017
    Keywords: biomarkers ; Bluegill ; sediment ; pollution ; EFPC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The temporal expression of various biological rsponses was determined in Bluegill SunfishLepomis macrochirus exposed under controlled laboratory conditions to sediment containing high concentrations of polynuclear aromatic hydrocarbons, polychlorinated biphenyls and heavy metals. Liver, gill, blood, kidney, brain, spleen and intestine were removed from Sunfish sampled at 1, 2, 4, 8, 16, and 40 weeks post-exposure. Biomarker data were recorded for specific proteins, enzymatic activities, DNA integrity, and histopathology. Biomarkers in the laboratory exposed fish were similar to those of indigenous Sunfish sampled from the site of origin of the contaminated sediment. Several patterns of development of biomarkers over time were also evident. For example, the responses of certain biomarkers are not time-dependent (i.e., intestine and gill ATPase activities) while that of others, such as brain ATPase activity, liver cytochrome P450 and NADPH content, stress proteins, chromatin proteins and DNA strand breaks, fluctuate over time. Still other biomarkers, such as EROD activity, zinc protoporphyrin content of the blood, and DNA adducts, showed marked increases over time. Such patterns need to be considered when comparing laboratory and field results and deciding which biomarkers to use for biomonitoring programs. Implications for natural selection and population/community level responses are also discussed.
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  • 91
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    Ecotoxicology 2 (1993), S. 175-184 
    ISSN: 1573-3017
    Keywords: fluctuating asymmetry ; phenodeviant ; biotest ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Developmental stability refers to the ability of a developing organism to produce a consistent phenotype in a given environment. It provides a simple, reliable method of detecting stressed populations and monitoring their recovery. The most common measure of developmental instability, fluctuating asymmetry, assesses minor deviations from perfect bilateral symmetry in traits that are normally symmetrical. Measures of developmental instability are based upon the concept of developmental invariance. The biotest approach consists of the simultaneous analysis of developmental instability (and related physiological instability) in a variety of species.
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  • 92
    ISSN: 1573-3017
    Keywords: chemicalpollution ; fish ; sediment ; San Francisco Bay ; liver diseases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Starry flounder (Platichthys stellatus), white croaker (Genyonemus lineatus) and sediments were collected annually from selected sites within San Francisco Bay, and a reference site in Bodega Bay between 1984--1991. Fish livers were examined for toxicopathic lesions and analysed for selected chlorinated hydrocarbons (CHs) such as PCBs, DDTs, chlordanes and dieldrin; sediment and fish stomach contents were analysed for polycyclic aromatic hydrocarbons (PAHs) and CHs; and bile was analysed for PAH metabolites. Sediment concentrations of PAHs, PCBs and DDTs; bile concentrations of PAH metabolites; and liver concentrations of PCBs, dieldrin and chlordanes were generally significantly higher at all San Francisco Bay sites compared to the Bodega Bay reference site. For both species, hydropic vacuolation of biliary epithelial cells was the most prevalent liver lesion detected and was statistically associated with sediment and tissue concentrations of PAHs or their metabolites, PCBs, DDTs, chlordanes and dieldrin. Temporal trends analyses showed that at Hunters Point, sediment PAHs and CHs increased between 1984--1991, while liver concentrations of CHs decreased. Liver concentrations of dieldrin in starry flounder decreased at all three San Francisco Bay sites
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  • 93
    ISSN: 1573-3017
    Keywords: Ameriurusnebulosus ; biomarkers ; sediment ; genotoxicity ; oxidativestress ; cytochrome P450
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Brown bullhead (Ameriurus nebulosus) were collected from three sites in the Niagara River ecosystem in June and September of 1991, and sediment samples from these sites were obtained in July 1991. The sites were located in the Buffalo River, the Niagara River adjacent to the Love Canal dump site, and in Black Creek, a Canadian tributary of the Niagara River which served as a reference site. Sediment samples from these sites contained measurable concentrations of various polycyclic aromatic hydrocarbons (PAHs) and chlorinated hydrocarbons (CHs). However, the Buffalo River and Love Canal samples were significantly more contaminated than those from Black Creek. Moreover, Buffalo River samples contained greater PAH concentrations than samples from the Love Canal, while the reverse was observed for CHs. Bile and liver of bullhead were used for the following analyses: fluorescent aromatic compounds in bile, a measure of exposure to PAHs, microsomal cytochrome P450 (CYP) and P450IA (CYP1A) contents and ethoxyresorufin-O-deethylase (EROD) activities, total glutathione (TH-GSH) concentrations, concentrations of 8- oxodeoxyguanosine (8-oxo-dG), and concentrations of hydrophobic DNA adducts (as measured by 32P-postlabelling). Additionally, a laboratory experiment was performed to examine CYP1A-associated responses in bullhead exposed to the model inducer, β- naphthoflavone (BNF). Results from the laboratory induction study were generally consistent with those observed in the field study, but the field study results suggested induction of CYP1A in bullhead from the reference site (Black Creek). For both field collections, fish from the Buffalo River displayed the greatest concentrations of fluorescent compounds in bile and hepatic DNA adducts, whilst fish from the Love Canal site displayed the greatest microsomal CYP1A concentrations and EROD activities. TH- GSH concentrations were significantly greater in Buffalo River fish versus Black Creek only for the June sampling. No statistically significant differences in 8-oxo-dG concentrations in bullhead hepatic DNA were observed among the sites at either sampling date. The different patterns in biochemical responses observed were consistent with sediment chemistries, and these results suggest that exposure of feral teleosts to different suites of bioavailable contaminants can be associated with expression of a characteristic array of biochemical responses
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  • 94
    ISSN: 1573-3017
    Keywords: DDT ; DDE ; DDD ; equilibrium partitioning ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Many of the most biologically productive portions of streams are backwater areas which support large populations of benthic macroinvertebrates. The sediments in these locations and their associated macroinvertebrate communities are frequently subjected to chemical inputs and physical perturbations. Historically, assessment of the effects of contaminants in sediments have emphasized chemical analyses and either laboratory toxicity tests or in-stream monitoring of benthic macroinvertebrate community structure. However, combining the chemical and biological approaches provides a more powerful assessment technique. Such an integrated approach, combining laboratory water-only and sediment toxicity tests with Hyalella azteca and Chironomus tentans, field surveys of benthic macroinvertebrate community structure and evaluation of chemical data using equilibrium partitioning theory was used to assess the effects of DDT, DDE and DDD (collectively termed DDTR) in the sediments of the Huntsville Spring Branch-- Indian Creek (HSB--IC) stream system in the southeastern USA. Benthic macroinvertebrate populations in the HSB--IC system still appear to be adversely affected by DDTR residues within the sediments even though DDT discharges to the stream were stopped over 20 years ago and a major remediation project was completed in the late 1980s. This conclusion is based on a weight of evidence approach which incorporates (1) the observed sediment toxicity to C. tentans and H. azteca in laboratory tests, (2) the identification of DDTR as the likely cause of effects observed during laboratory toxicity tests, (3) the absence of appropriate sensitive species from groups such as the Ephemeroptera, Plecoptera, Trichoptera and Amphipoda, (4) the presence of reduced numbers of both total individuals and species of chironomids and oligochaetes relative to nearby streams not contaminated by DDTR and (5) the observed distribution of benthic macroinvertebrates in relation to organic carbon-normalized concentrations of DDTR and equilibrium partitioning-based predicted sediment toxic units of DDTR
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  • 95
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    Journal of agricultural and environmental ethics 9 (1996), S. 42-60 
    ISSN: 1573-322X
    Keywords: applied philosophy of science ; science in policy ; risk assessment ; fact-value dichotomy ; biotechnology ; genetically modified organisms ; deliberate release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract To make more responsible decisions regarding risk and to understand disagreements and controversies in risk assessments, it is important to know how and where values are infused into risk assessment and how they are embedded in the conclusions. In this article an attempt is made to disentangle the relationship of science and values in decision-making concerning the deliberate release of genetically modified organisms (GMOs) into the environment. This exercise in applied philosophy of science is based on Helen Longino's contextual empiricism which attempts to reconcile the ‘objectivity’ of science with its social and cultural construction. Longino distinguishes different levels of research on which values apparently contextual with respect to a given research program can shape the knowledge emerging from that program. Her scheme is applied for locating and identifying the values that affect environment risk assessments of the field experiments with GMOs. The article concludes with some provisional suggestions for the decision process and the role of scientists in it.
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  • 96
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    Ecotoxicology 8 (1999), S. 147-166 
    ISSN: 1573-3017
    Keywords: Pesticides ; risk assessment ; bumblebees
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Bumblebees are important pollinators of many crops and wild flowers and there are both conservation and economic reasons for taking action to assess the impact of pesticides on bumblebees. Pesticide risk assessments for honeybees are based on hazard ratios which rely on application rates and toxicity data and are unlikely to be appropriate for bumblebees. Bumblebees are active at different times and on different crop species and are, therefore, likely to have different exposure profiles. Unlike honeybees, deaths of bumblebees due to pesticides are unlikely to be reported, since the bees are not kept domestically and will die in small numbers. This paper highlights the differences in the potential risk posed by pesticides to bumblebees from that of honeybees. This is based on their exposure through use of crops and flowering weeds and on available data on toxicity of pesticides. This information is also intended as a source document for information on the foraging behavior and phenology of bumblebees for use in risk assessment for pesticides.
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  • 97
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    Ecotoxicology 9 (2000), S. 287-297 
    ISSN: 1573-3017
    Keywords: honeybees ; pesticides ; risk assessment ; integrated pest management ; pollen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A method for assessing the risk for honeybees from pesticide exposure via pollen is proposed. Four pesticides, selected as markers, were monitored in pollen samples collected in two sampling areas, one located in an intensive agricultural area and the other far from direct pesticide impact. Analytical results were consistent with use patterns of the chemicals and their physico-chemical and persistence properties. For a preliminary estimate of bee exposure via pollen, both by ingestion and by contact, an exposure index was developed, based on physico-chemical properties, persistence and application rates. On the basis of the exposure estimates and acute toxicological data (ingestion and contact LD50), Toxicity Exposure Ratios (TERs) were calculated as indicators of the risk for honeybees due to this particular exposure route. TER values were compared to Hazard Quotient (HQ), calculated as the ratio between application rate and the LC50 value, according to European guidelines, showing a satisfactory agreement. The advantage of the above described procedures is that the environmental fate of the chemicals, and not only application rates, are taken into account. This approach may represent a preliminary tool for a comparative screening of the risk for pollinator insects due to this particular exposure route.
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  • 98
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    Water, air & soil pollution 101 (1998), S. 309-321 
    ISSN: 1573-2932
    Keywords: Arctic ; atmospheric deposition ; contaminants ; lead-210 ; mercury ; sediment ; sewage ; subarctic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The history of atmosheric mercury inputs to remote arctic regions can be measured in lake sediment cores using lead-210 chronology. In this investigation, total mercury deposition is measured in sediments from Imitavik and Annak Lakes on the Belcher Islands in southeastern Hudson Bay, an area in the southern Canadian Arctic with no history of local industrial or agricultural sources of contamination. Both lakes received background and atmospheric inputs of mercury while Annak also received mercury from raw domestic sewage from the Hamlet of Sanikiluaq, a growing Inuit community of about 550 established in the late 1960's. Results from Imitavik show that anthropogenic mercury inputs, apparently transported through the atmosphere, began to appear in the mid-eighteenth century, and continued to the 1990's. Annak had a similar mercury history until the late 1960's when disposal of domestic sewage led to increased sediment and contaminant accumulation. The high input of mercury to Annak confirms that Sanikiluaq residents are exposed to mercury through native food sources.
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  • 99
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    Water, air & soil pollution 115 (1999), S. 71-81 
    ISSN: 1573-2932
    Keywords: ecotoxicology ; longe-range transport ; pesticides ; residues ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Concern has arisen about the possible ecological effects of persistent pesticides that become airborne during or after application and are transported to regions far away from where they were applied. In this paper an ecotoxicological approach is outlined that may support assessments of products suspected of long-range transport capacity. It is proposed that the risk is estimated from a classical PNEC/PEC comparison for the surface layer of a remote area, where PEC is estimated from dose rate, emission factors, atmospheric residence time and persistence, while PNEC is estimated from ecotoxicological information collected as part of the registration procedure. According to this "null model", risk assessment of pesticides subject to long-range transport is not different from the usual risk assessment, provided that due attention is paid to losses occurring during transport and accumulation in remote areas with low temperature. A simplified equation is derived for estimating PEC from the recommended dose rate, which shows that the concentration in the remote area is higher than in the target area only if its residence time is at least two order of magnitude longer than the corresponding value in the target area. A review of ecotoxicity data for effects of volatile pesticides on arthropods indicates that effect levels in the air compartment are far above the concentrations of concern in long-range transport. Arguments supporting the view that remote areas, specifically the polar regions, are characterized by ecosystems that are more vulnerable than the ones on which the usual risk assessment is based, are reviewed. Although residues of organochlorines are of concern, there does not seem to be concrete epidemiological or experimental evidence about effects of modern pesticides on wildlife in remote areas. It is concluded that there is no reason to reject the "null model" at the moment, however, in view of the large uncertainty involved, it is proposed that the maximum acceptable ratio between PNEC and PEC be increased by an extra safety factor.
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    Water, air & soil pollution 118 (2000), S. 407-418 
    ISSN: 1573-2932
    Keywords: DOC ; release kinetics ; sediment ; Water Soluble Organic Carbon (WSOC) ; wetland soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Release kinetics of Water Soluble Organic Carbon (WSOC) from a wetlandsoil and a river bottom sediment were investigated under variousexperimental conditions in the laboratory. The laminar sublayerconcept was applied to model the release process. The resultsindicate that the release process can be characterized by atypical first order equation derived from the laminar sublayermodeling. The mass transfer rate constants of the releaseprocess increased with the increase in flow velocity following apower function. Due to texture difference, the transfer rateconstant of the wetland soil is about one order of magnitudelarger than that of the river bottom sediment. The influences oftemperature and pH on the release kinetics are discussed.
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