Risk assessment as a management tool for inactive hazardous materials disposal sites

A protocol for risk assessment at inactive hazardous material disposal sites has been developed by using mathematical modeling and estimation techniques. Compared with ranking models, the protocol yields quantitative results with a minimum of input data that may be used to select among management, scientific, or engineering alternatives for the site. This article reviews the background, presents the protocol, illustrates the application of the protocol, and demonstrates the use of the protocol in conjunction with thecritical environmental area concept. Comparisons are also presented with other model systems such as the EPA HRS.     

Contemporary (1979-1988) and inferred historical status of headwater lakes in North Central Ontario, Canada

Fifty-six headwater Canadian Shield lakes were repetitively sampled from 1979 to 88 to determine their response to changes in acidic deposition of the period. Annual wet sulphate loadings varied between 38 and 83 meq m(-2), with highest deposition in the late 1970s followed by somewhat lower but variable deposition in the 1980s. Median pH of the lakes increased 0.42 pH units from 1979 to 1985 and decreased by 0.15 units between 1985 and 1988. Short water renewal times (x=1.1 y) promoted rapid equilibration. Since lake were so responsive to changes in SO4(2-) inputs, they were at or near steady state at all times. Comparison of predicted original pH and ANC with 1979 data indicate a median decline of 0.45 pH units and a loss of 34 microeq litre(-1). ANC. Four of 9 lakes were found to be historically fishless, based on the continued presence of Chaoborus americanus in sediment cores. The remaining five lakes historically had fish populations, but fish were not collected in 1979 when pH ranged betwen 4.6 and 5.3. By 1987, fish species were found in five of these lakes where pH had increased on average by 0.9 pH units. Our data indicate that water quality improvements could allow for the reinvasion or resumption of recruitment for a significant number of Ontario lakes.     

Distributional analysis of regional benefits and cost of air quality control

The methodology and results of an analysis of benefits and costs of air quality control for an urban region in Florida are given. The machinery used considers the spatial distribution of (a) emission sources, (b) the ambient levels resulting from local meteorological conditions and geographic features, and (c) the socioeconomic characteristics of the impacted population groups. This facilitates an examination of the distributional aspects of costs and benefits associated with various control scenarios. With appropriate adaptation and inputs the steps in our analysis should apply to a distributional benefit/cost analyses for any region.     

TRICK OR TREAT? AN OFFER TO OBTAIN METERED WATER1

ABSTRACT: In this paper we examine the possible reasons why individuals who live in homes facing a flat monthly rate for water accept or reject an offer to have water metering devices installed at no cost to them. A logit model is used to model the discrete choice of acceptance. Since the demand for metering is directly tied to water demand, we estimate demand models for unmetered households in the Reno/Sparks metropolitan area using contingent data obtained by presenting households with hypothetical prices they might encounter under a metering system. Conditional logit and demand models are then used to examine the potential for metering to promote water conservation in the arid Reno/Sparks, Nevada metropolitan area.