Evaluation of the ranking probabilities for partial orders based on random linear extensions

Partial order theory and Hasse diagrams appears to be a promising tool for decision-making in environmental issues. Alternatives or objects are said to be partial ordered when it is impossible to find a mutual relationship (< or >) for all criteria. This is often the case in complicated real life situations. However, sometimes it is attractive to apply a total order, i.e. linear rank, and not just the partial order. Based on ranking probabilities and linear extensions it is possible to derive a total order. A linear extension is a projection of the partial order into a total order that comply with all the relations in the partial order. When all linear extensions are known the ranking probabilities can be found as the probability for an object to occupy a specific rank. However, the total number of linear extensions is proportional with the faculty of the number of objects in the partial order. Therefore it is practically impossible to identify all possible linear extensions for partial orders with more than around 20 objects. This study reviews and evaluates a method which estimates the ranking probability based on sampling of a minor random fraction of the linear extensions. Using standard statistics the necessary number of random linear extensions is described as a function of the ranking probability estimate and the restrictions on the confidence interval around the ranking probability. The analysis reveals a smaller systematic uncertainty, which occurs due to the random selection of ranking between two incomparable objects. The discrepancy appears to be dependent on the structure of the partial order. The method using random linear extensions thus appears as a valuable tool for analysing larger partially ordered sets, which are practically impossible to handle using the total set of linear extensions.     

用物元分析进行水质环境监测优化布点的研究

本文首次提出利用物元分析对水质环境监测优化布点的新方法。在确定了最佳和最次理想点基础上，建立了标准事物和节域事物的物元矩阵。该法具有计算简便、分析合理和容易推广的优点。     

Prediction of overall persistence and long-range transport potential with multimedia fate models: robustness and sensitivity of results

The hazard indicators persistence (P) and long-range transport potential (LRTP) are used in chemicals assessment to characterize chemicals with regard to the temporal and spatial extent of their environmental exposure. They are often calculated based on the results of multimedia fate models. The environmental and substance-specific input parameters of such models are subject to a range of methodological uncertainties and also influenced by natural variability. We employed probabilistic uncertainty analysis to quantify variance in P and LRTP predictions for chemicals with different partitioning and transport behavior. Variance found in the results is so large that it prevents a clear distinction between chemicals. Additionally, only small improvements are observed when evaluating the results relative to a benchmark chemical. This can be explained by the dominance of substance-specific parameters and the only small direct influence of environmental parameters on P and LRTP as model outcomes. The findings underline the importance of learning how environmental conditions cause variability in substance behavior for improved substance ranking and classification.     

What Price Air Quality the Cost of New Jersey’s Inspection/Maintenance Program

Selection of acceptable sites for industrial facilities, especially hazardous waste management facilities, can be made using a relatively new technique referred to as “fuzzy set analysis.” The methodology presented is applicable to multiple alternative decision making, when criteria are of unequal importance, and is based on the concept of establishing a subjective value for each alternative according to each criterion, and then raising the subjective value to a power commensurate with the relative importance of the criterion. This exponential weight is calculated on the basis of a preferential analysis of criteria comparisons. Apart from the ranking of the alternatives, fuzzy set analysis provides a quantitative representation of the community opinion of the order of importance of the criteria, regardless of the sites being considered. Based on the importance factors averaged from a cross section of the community, public concern could also be ranked.     

Multi-element analysis of road-deposited sediment in an urban drainage basin, Honolulu, Hawaii

Road-deposited sediment (RDS) and its associated contaminant load play a critical role in degrading receiving water bodies. Few quantitative multi-element RDS studies exist, and there are none from Hawaii. This lack of baseline data combined with concerns with high concentrations of Pb and Cu in fish and enrichment of Cu, Pb and Zn in bed sediments from Manoa Stream, Hawaii, lead to a detailed characterization of RDSs in Manoa basin. Data for a total analysis of 23 elements using inductively coupled plasma atomic-emission spectrometry and instrumental neutron activation analysis and 16 elements using a 0.5 M HCl partial leach are presented for RDSs and background soils. Concentration data, comparisons with environmental guidelines, and concentration enrichment ratios (CERs) all indicate that RDS in Manoa has a significant degree of anthropogenic pollution. The most environmentally important elements were Pb, Sb and Zn. Concentrations of these elements, primarily vehicle contributed, compare favorably with those from other studies of RDS. The high mean concentration of Pb (151 mg/kg) compared to background soils (13 mg/kg) indicates remobilization of Pb previously stored in soils and transported to road surfaces by water erosion processes. The higher Pb CER(Total) in RDSs compared to bed sediments from Manoa Stream suggests a potential link via ubiquitous storm drains and subsequent dilution with less contaminated fluvial sediments. Data from the HCl leach also support Pb and Zn as having significant anthropogenic signals, and Cu having a moderate signal. These data indicate that RDSs in Manoa basin are generally contaminated with certain potentially toxic elements and the legacy of past use of leaded gasoline is still a concern in this urban drainage system.     

Indicators for persistence and long-range transport potential as derived from multicompartment chemistry-transport modelling

Total environmental and compartmental residence times as a measure for persistence as well as indicators for long-range transport potential (LRTP) have been derived from global geo-referenced modelling and LRTP is characterized in two geographic directions for the first time. A dynamic multicompartment chemistry-transport model (MCTM) was used to study the fate of the insecticides DDT and alpha-hexachlorocyclohexane (alpha-HCH) during the first 2 years upon entry. The indicators for LRTP were defined such as to address the tendencies of substance distributions to migrate ('plume displacement', PD) and to spread into remote areas ('spatial spreading', SS). The indicators deliver values as function of time upon entry. With the aim to address the effect of location of entry on environmental fate, scenarios of emission from the territories of seven countries were studied. It was found that the effect of location of entry on the spatial scale of countries (400-4000 km) is significant for the compartmental distribution and the inter-compartmental mass exchange fluxes (e.g., number of atmospheric cycles, 'hops'). Location of entry introduces uncertainties in the order of a factor of 5 for the total environmental residence time, tau(overall), and a factor of 5-20 for PD and SS. For the 2nd year upon entry into the environment, tau(overall)=317-1527 days are predicted for DDT and 101-463 days for alpha-HCH. The influence of location of entry does affect the substance ranking, i.e. we cannot simply state that DDT is more persistent than alpha-HCH, but for one scenario studied, application in China, the opposite is predicted. Precipitation patterns proved to be significant, besides other climate parameters, for atmospheric residence time. Integration of the location of entry in chemicals risk assessments is therefore recommended. In general, persistence and some indicators for LRTP, pertinent to their definition, refer to the fate of a large fraction, e.g., 63% (=1-1/e) or 90%, but not the total substance burden. The choice of this fraction may have the consequence of a normative step which defines the spatial and temporal extensions of a related chemicals risk assessment and may affect substance ranking.     

The evaluation of the equilibrium partitioning method using sensitivity distributions of species in water and soil

The equilibrium partitioning method (EqP-method) can be used to calculate soil quality standards (expressed in mg/kg) from aquatic quality standards (expressed in microg/l) using a partitioning coefficient. The validity of this application of the EqP-method was studied comparing aquatic with terrestrial toxicity data. The data set collected for deriving environmental quality standards in the Netherlands, was used for this study. For 10 organic substances (chlorpyrifos, atrazine, carbofuran, pentachlorophenol, chlordane, aldrin, trichlorobenzene, heptachlor, trichlorophenol and trichloroethene) and for 8 metals, sufficient data were available. The aquatic toxicity data were multiplied by the partitioning coefficient in order to obtain aquatic data expressed in mg/kg. For some compounds the terrestrial toxicity data were significantly higher than the aquatic data but for other compounds it was the other way around. These differences indicate that the EqP-method can give significant over-or underestimations, due to inaccurate partitioning coefficients or differences in species sensitivities. These over- or underestimations can have an impact on the setting of environmental quality standards which are based on the hazardous concentration 5% (HC5) values. The uncertainty in the calculation of HC5 values attributed to the use of the EqP-method, was quantified. The HC5 values derived using the EqP-method were in 5% of the cases more than 20 times higher than the corresponding HC5 values that were derived directly from soil toxicity tests. Despite of this uncertainty the use of the EqP-method can still be advocated for setting soil quality guidelines when only a very limited number of terrestrial toxicity data are available.     

Pesticides and groundwater quality protection

A simple approach for ranking the leaching of pesticides from surface soil is presented and tentatively calibrated with field data from an agricultural area. The approach is based on the calculation of a leaching index indicating the proportion of active ingredient, with respect to the quantity applied, leaching from a soil model in a given time interval (one year). In the selected area, 85 wells tapping an unconfined aquifer were sampled for groundwater pesticide residue analysis, in order to explore the index region between leachers and nonleachers.     

APCA Financial Statements for FY 1980–81

Abstract

Emerging environmental control technologies are frequently characterized in terms of their removal efficiencies. Based on a limited number of tests, the environmental engineer must typically predict the true removal efficiency along with its level of uncertainty. This paper provides a “road map” (based on the number of non–detects, the underlying distribution of data, and whether data are paired or unpaired) for calculating such uncertainty. Both confidence intervals and hypothesis tests are considered.     

Life cycle assessment of active and passive groundwater remediation technologies

Groundwater remediation technologies, such as pump-and-treat (PTS) and funnel-and-gate systems (FGS), aim at reducing locally appearing contaminations. Therefore, these methodologies are basically evaluated with respect to their capability to yield local improvements of an environmental situation, commonly neglecting that their application is also associated with secondary impacts. Life cycle assessment (LCA) represents a widely accepted method of assessing the environmental aspects and potential impacts related to a product, process or service. This study presents the set-up of a LCA framework in order to compare the secondary impacts caused by two conceptually different technologies at the site of a former manufactured gas plant in the city of Karlsruhe, Germany. As a FGS is already operating at this site, a hypothetical PTS of the same functionality is adopted. During the LCA, the remediation systems are evaluated by focusing on the main technical elements and their significance with respect to resource depletion and potential adverse effects on ecological quality, as well as on human health. Seven impact categories are distinguished to address a broad spectrum of possible environmental loads. A main point of discussion is the reliability of technical assumptions and performance predictions for the future. It is obvious that a high uncertainty exists when estimating impact specific indicator values over operation times of decades. An uncertainty analysis is conducted to include the imprecision of the underlying emission and consumption data and a scenario analysis is utilised to contrast various possible technological variants. Though the results of the study are highly site-specific, a generalised relative evaluation of potential impacts and their main sources is the principle objective rather than a discussion of the calculated absolute impacts. A crucial finding that can be applied to any other site is the central role of steel, which particularly derogates the valuation of FGS due to the associated emissions that are harmful to human health. In view of that, environmental credits can be achieved by selecting a mineral-based wall instead of sheet piles for the funnel construction and by minimising the steel consumption for the gate construction. Granular activated carbon (GAC) is exclusively considered as the treatment material, both in-situ and on-site. Here it is identified as an additional main determinant of the relative assessment of the technologies since it is continuously consumed.     

Database uncertainty as a limiting factor in reactive transport prognosis

The effect of uncertainties in thermodynamic databases on prediction performances of reactive transport modeling of uranium (VI) is investigated with a Monte Carlo approach using the transport code TReaC. TReaC couples the transport model to the speciation code PHREEQC by a particle tracking method. A speciation example is given to illustrate the effect of uncertainty in thermodynamic data on the predicted solution composition. The transport calculations consequently show the prediction uncertainty resulting from uncertainty in thermodynamic data. A conceptually simple scenario of elution of uranium from a sand column is used as an illustrating example. Two different cases are investigated: a carbonate-enriched drinking water and an acid mine water associated with uranium mine remediation problems. Due to the uncertainty in the relative amount of positively charged and neutral solution species, the uncertainty in the thermodynamic data also infers uncertainty in the retardation behavior. The carbonated water system shows the largest uncertainties in speciation calculation. Therefore, the model predictions of total uranium solubility have a broad range. The effect of data uncertainty in transport prediction is further illustrated by a prediction of the time when eluted uranium from the column exceeds a threshold value. All of these Monte Carlo transport calculations consume large amounts of computing time.     

Effects of time-averaging climate parameters on predicted multicompartmental fate of pesticides and POPs

With the aim to investigate the justification of time-averaging of climate parameters in multicompartment modelling the effects of various climate parameters and different modes of entry on the predicted substances' total environmental burdens and the compartmental fractions were studied. A simple, non-steady state zero-dimensional (box) mass-balance model of intercompartmental mass exchange which comprises four compartments was used for this purpose. Each two runs were performed, one temporally unresolved (time-averaged conditions) and a time-resolved (hourly or higher) control run. In many cases significant discrepancies are predicted, depending on the substance and on the parameter. We find discrepancies exceeding 10% relative to the control run and up to an order of magnitude for prediction of the total environmental burden from neglecting seasonalities of the soil and ocean temperatures and the hydroxyl radical concentration in the atmosphere and diurnalities of atmospheric mixing depth and the hydroxyl radical concentration in the atmosphere. Under some conditions it was indicated that substance sensitivity could be explained by the magnitude of the sink terms in the compartment(s) with parameters varying. In general, however, any key for understanding substance sensitivity seems not be linked in an easy manner to the properties of the substance, to the fractions of its burden or to the sink terms in either of the compartments with parameters varying. Averaging of diurnal variability was found to cause errors of total environmental residence time of different sign for different substances. The effects of time-averaging of several parameters are in general not additive but synergistic as well as compensatory effects occur. An implication of these findings is that the ranking of substances according to persistence is sensitive to time resolution on the scale of hours to months. As a conclusion it is recommended to use high temporal resolution in multi-media modelling.     

A graphical technique for determining major components in a mixed aerosol. I. Descriptive aspects

A persistent problem in aerosol science is how best to determine the compositions of the major components in mixed samples. This paper presents a graphical technique for extracting the elemental compositions of the crustal, marine, and general pollution components in large suites of samples from single sites. Log-log scatter diagrams are constructed, with the vertical axis being the X/Al ratios of the samples (where X is an element of interest and Al is the crustal reference element) and the horizontal axis being either Na/Al or Se/Al (where Na and Se are marine and pollution reference elements, respectively). If the crustal component is sufficiently enriched in enough samples, a horizontal “compositional tail” of X/Al will appear at the left-hand end of the plots, with an asymptotic value equal to the ratio in the pure crustal aerosol. If the second component is sufficiently enriched in enough samples, its compositional tail will appear as a 45° zone at the right-hand end of the plots. Depending on the choice of component, the asymptotic value of this tail will be the X/Se ratio in the pollution component or the X/Na ratio in the marine component. When the sample set is large enough, compositions of components can frequently be determined to uncertainties of 10% or less. Results for elements in a large suite of aerosol samples from Narragansett, RI, measured by neutron-activation analysis, reveal well-defined compositional tails for most elements and a smooth progression of elements from purely crustal to purely pollution derived. This graphical technique can also be applied to precipitation, provided only that it has been sampled and analyzed in ways that make its data directly analogous to those of aerosol.     

Interactive valuation: the social construction of the value of ecological services

Two different perspectives mark the discourse about the valuation of ecological services: a positivistrealist perspective, emphasising the use of objective scientific procedures to discover true values of ecological services truth is seen as the basis for social change; and a constructivist perspective, emphasising value as emerging from interaction. Value is an agreement and hence effective in social change. This paper examines the implications of the latter for valuation. It first analyses the current dominant practice of environmental valuation in terms of its epistemological assumptions. It then examines how a constructivist perspective colours the expectation of societal effectiveness of environmental valuation. Both themes reflect debated issues in ecological economics (e.g. O'Connor, 1998). 'Double hermeneutics' refers to the capacity to make sense on the basis of the sense-making of others. Environmental valuation in economics attempts a sort of 'triple hermeneutics': economists make sense of how people value the environment, in order to influence the sense-making of policy-makers and the general public. This paper argues that environmental valuation alternatively can be carried out as a constructivist procedure that reduces triple to single hermeneutics. Environmental valuation aims at societal change through internalisation of the costs of ecological services. Knowledge of the 'real' costs is expected to influence behaviour. Our analysis calls for the wider use of an alternative approach 'interactive valuation'. That is, the people whose behaviour incurs environmental costs are assisted to use environmental valuation methods themselves in order experientially to learn to internalise the environmental costs of their activities. It is not the researcher or expert who analyses and learns, so that he/she can transfer the learning to others, but the 'others' themselves who analyse and learn. In practice, this means that scientific valuators are not limited to discovering 'real', objective values, but also engage in developing tools for discovery learning by people themselves. The paper elaborates concrete experiences in the analysis and development of farming systems.     

Scientific activities of Euro Chlor in monitoring and assessing naturally and man-made organohalogens

In this paper a review of the scientific activities and research programmes carried out by Euro Chlor, the European Federation of chlor-alkali producers is presented according to two main axes: marine risk assessments with statistical analysis of monitoring data, temporal trends of emission levels and environmental concentrations. The methodology applied in each field is briefly presented and then illustrated by several practical examples. As a large part of the uncertainties in assessing the risk of a chemical to a given species or ecosystem often comes from the difficulty in evaluating the exposure level, Euro Chlor has chosen to use a monitoring approach, the exposure level being estimated from a statistical analysis of measured concentrations levels in water and sediment from rivers, estuaries and coastal areas. As the modelling approach often used by the authorities to estimate the predicted environmental concentration value is starting from roughly estimated emission levels, Euro Chlor collated emissions data from about 80 production plants in order to reduce the uncertainty associated with the default values introduced in the modelling approach.A brief review of the European emission levels for chlorinated organic substances is given as well as the temporal trends of both emission and environmental levels. A methodology to quantify the trends in measured concentrations at local and regional scales is briefly described. The observed decreasing trends demonstrate the continuous progress made by the Euro Chlor member companies in protecting the environment.Finally, the problems linked to the simultaneous presence in the environment of naturally and man-made chlorinated substances are briefly reviewed. To stimulate further research in the field, two key questions are raised which have not yet found a satisfactory answer: how to quantify natural background levels and how to quantify global persistence in the environment?