摘要:

ABSTRACTThe role of Fe in Pb solubilization by ethylenediamirtetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) from a highly contaminated (21% Pb by weight) battery reclamation site soil was investigated using batch extraction and sequential fractionation experiments. Based on relative complexing ability, soluble Fe(III) should inhibit Pb recovery using chelating agents, particularly under acidic conditions. Despite a large pool of available Fe (6.7% of soil by weight) and a marked increase in soluble Fe(III) with decreasing pH, Pb solubilization was nearly pH invariant. Since only 12% of FeT compared to 86% of PbT was solubilized by 4 × 10−2M EDTA at pH 6, Pb and Fe apparently exist in differentially reactive forms within the soil. A nine-step chemical fractionation procedure confirmed that 80% of the soil Pb was present in non-detrital (soluble, weakly sorbed) forms in contrast to 94% of Fe existing in detrital (oxide occluded, residual) fractions. The kinetically slow dissolution of indigenous Fe oxides compared to anthropogenically-added Pb makes unnecessary strongly alkaline conditions to reduce competitive chelation by Fe in soil decontamination processes. Although generally regarded as important in metal fixation, the Fe oxides retained<1% of the total soil

ISSN:0882-5696    

DOI:10.1089/hwm.1989.6.223

年代:1989

数据来源: MAL

摘要:

ABSTRACTAn assessment of risks associated with dioxin-contaminated soil, primarily attributable to Centers for Disease Control (CDC) personnel, has been criticized as too conservative for both residential and industrial locations. In analysis of risks at industrial locations, where the childhood oral ingestion pathway may be neglected, adequate quantification of the dermal exposure pathway is particularly important. Reexamination of the experiment on which CDC assumptions regarding dermal absorption efficiency were based indicates that CDC's dermal risk assessment is not conservative. Results generated using a fugacity-based dermal exposure model incorporated in a physiologically based pharmacokinetic model are presented. Dermal bioavailabilities well in excess of that assumed in the CDC assessment are predicted.

ISSN:0882-5696    

DOI:10.1089/hwm.1989.6.231

年代:1989

数据来源: MAL

摘要:

ABSTRACTApproximately 7 Gg of high P content spent refinery catalyst (SRC) are produced as a by-product of the petroleum refining industry each year in the U.S. This spent refinery catalyst is classified as a hazardous waste due to its low pH, and is currently disposed of in hazardous waste storage facilities. The potential exists for beneficial re-use of SRC as P fertilizer for crops. This study was conducted to determine the availability and uptake of P and metals from SRC to dryland winter wheat in eastern Colorado. A field study was conducted for two years at five sites with a range of soil properties. Treatments included 6 rates of SRC (0, 10, 20, 40, 80, and 160 g/m2), and equivalent rates of a commercial source of P (triple superphosphate (TSP)) based on P content. Grain, straw, and boot stage plant materials were evaluated for yield and elemental uptake. Surface soils at grain harvest were evaluated for P availability, pH, and metal availability. Yield and P uptake data showed that SRC equaled TSP in providing P to wheat. The SRC significantly lowered surface soil pH, but in general no differences existed between SRC and TSP with regard to concentration of metals found in plant parts or in surface soils at grain harvest. Based on the parameters that were evaluated in these studies, there appears to be no adverse effect of using SRC as a P source for dryland winter wheat.

ISSN:0882-5696    

DOI:10.1089/hwm.1989.6.241

年代:1989

数据来源: MAL

摘要:

ABSTRACTA series of cation doped Portland cement samples containing Pb2+and Cr3+ions have been examined by x-ray photoelectron spectroscopy (XPS) and low energy ion scattering spectroscopy (ISS). Evidence is presented for the location of the ions relative to the surface. The oxidation states after incorporaton and their possible chemical environments are discussed. A significant observation of the preferential surface location of Pb2+supports a model for the Pb2+induced retardation of cement setting by a surface blockage of the hydration process. Scanning electron microscopy and energy dispersive x-ray analysis have been used to examine sample morphology and cation distribution.

ISSN:0882-5696    

DOI:10.1089/hwm.1989.6.251

年代:1989

数据来源: MAL

摘要:

ABSTRACTA small, 3 by 9 by 0.9 m, experimental earthen liner was constructed using full-size compaction equipment. The liner was built utilizing six 15 cm thick compacted lifts. Water containing fluorescein and rhodamine WT dyes was allowed to infiltrate under ponded conditions for 46 days. Dye patterns observed during excavation of the liner indicated that lateral flow occurred between lifts. Although the US EPA hydraulic conductivity criterion for liners (

ISSN:0882-5696    

DOI:10.1089/hwm.1989.6.269

年代:1989

数据来源: MAL

摘要:

ABSTRACTThis article examines the problem of illegal disposal of hazardous wastes by small quantity generators (SQGs) and evaluates technical and policy alternatives for improving compliance. We show that illegal disposal is widespread and has three principal causes -- lack of enforcement, the high cost of disposal, and lack of information, in order of importance. Among the four technical alternatives -- expanded route services, on-site recycling, off-site treatment and recycling (including mobile treatment), and transfer stations -- expanded routes services and onsite recycling rank highest in terms of our evaluation criteria. The most promising policy alternatives for reducing illegal disposal are subsidies for expanding route services, and economic incentives using deposit-refund systems. As part of a comprehensive program to reduce illegal disposal increased enforcement will be essential. Enforcement programs should be coordinated at the local level, but they will need substantial state or federal funding to be effective.

ISSN:0882-5696    

DOI:10.1089/hwm.1989.6.281

年代:1989

数据来源: MAL

摘要:

ABSTRACTThis study was instigated to develop a computer model that (a) quantitatively evaluates competing research and development projects, and (b) assists in prioritizing such projects when resources are not sufficient to conduct all of them. An evaluation model was developed, based upon existing multiattribute utility theory but with some modification and innovation. The model, with user input, helps determine the relative weights of the factors or criteria used to evaluate the projects under consideration, and, again with user input, determines the utility function for each of the attributes. A computer program (which runs on any IBM-compatible personal computer under IBM- or MS-DOS Version 2.0 or later) was written to implement the model.A unique feature of this model is that it incorporates uncertainties of three types: (1) those dealing with the factor weights, (2) those dealing with the worth of each project with respect to each factor, and (3) those dealing with the utilities of the attributes. The model is adapted to run on personal computers as well as on larger ones, although the distribution version available is designed for personal computers. No special knowledge of the basic theory involved is required to exercise the computer model.Although the study was designed with the objective of dealing with competing research and development projects, the model is sufficiently general so that it may be applied to any problem of competing alternatives. Thus, it has wide application in the health, engineering, environmental, and decision sciences.

ISSN:0882-5696    

DOI:10.1089/hwm.1989.6.297

年代:1989

数据来源: MAL

摘要:

ABSTRACTThis paper presents an approach for quantifying, in monetary terms, the risks and potential liabilities associated with hazardous waste disposal options. An event tree analysis is used. Various causative events that could occur in the short and long term and their resultant consequences are identified. The probabilities, times of occurrence, and the financial implications of these events and their consequences are estimated. The TPR (Total Probable Risk) of a disposal option is then calculated and added to its present value cost, and the totalrisk-inclusivecost is used for the comparison of options.Because of the uncertainties involved in the management of hazardous wastes, it is imperative that comprehensive risk and liability evaluation be an integral part of the decision-making process for selection of hazardous waste disposal options. The risks associated with these options can often be intuitively assessed in a qualitative sense. Therefore, risk analysis techniques that produce only qualitative or semi-quantitative risk ratings of disposal options do not provide much additional input to the decision-maker. The technique described in this paper presents risks and liabilities as the added costs of a disposal option (TPR). Such representation is easily understood by managers and is useful as an aid to management decision-making. The technique also helps to identify areas for future risk-reduction efforts.

ISSN:0882-5696    

DOI:10.1089/hwm.1989.6.315

年代:1989

数据来源: MAL

ISSN:0882-5696    

DOI:10.1089/hwm.1989.6.xi

年代:1989

数据来源: MAL