Soil desiccation rate integration into empirical dust emission models for polymer suppressant evaluation.

Dust constitutes an environmental and human health menace in many regions of the world. The rate of soil desiccation is a significant determinant of the availability of fine soil particles for entrainment in air as dust. Dust suppressants such as polymer solutions can reduce soil desiccation rate, thereby reducing dust emission factor. Herein, a dust emission estimation methodology that involves the integration of desiccation time curves to find the average desiccation rate is formulated. This is combined with soil characteristics, stressor (environmental and possibly vehicle) characteristics and liquid content in soil to estimate potential emission factors. Using this methodology, the dust suppression potential of aqueous polyethylene oxide (PEO) solution was investigated experimentally with Na-montmorillonite (Na-mmt) as the model dust-generating material. PEO with a molecular weight of 8 x 10(6) and at aqueous concentrations ranging from 0.5 to 10 g/L, was mixed with 10 g of Na-mmt (surface area=31.82+/-0.22 m2/g) and desiccated for 700 h in a specially designed chamber at 25 degrees C and 30% relative humidity. The results show that generally, aqueous PEO is superior to distilled water as a dust suppressant for Na-mmt at concentrations in the range of 0.5-2.0 g/L. The experimental data obtained are introduced into the formulated estimation methodology, and potential emissions of dust from PEO-admixed Na-mmt are determined.

A quantitative methodology for indexing environmental sensitivity and pollution potential.

A methodology for rating the suitability of sites for the location of industrial facilities is formulated and applied to the case of a coal-fired power plant location. The methodology comprises two major interlinked components: the environmental plant location indexing component, which involves the identification, scaling and weighting of environmental sensitivity factors; and the impact analysis component, which involves the superimposition of the pollution generation impacts of an industrial facility on spatially gridded zones of various environmental sensitivities. For each rectangular areal unit defined by a square grid, the Unit Pollution Potential Index is determined by the severity and distribution of key environmental sensitivity factors and the coverage of superimposed pollutant effects as determined by contaminant fate and transport models. For any alternative site of a planned facility, the summation of the unit indices over the area of influence of the facility provides the quantitative Pollution Index, which can be used as a basis for comparison of alternative sites for planned facilities. For this paper, this methodology is applied to the hypothetical case of the siting of a coal-fired power plant in the northeastern region of the United States, in which three alternative sites are considered. The three sites: A, B and C yielded indices of 47.83, 47.91 and 47.6, respectively, indicating that site C is the most suitable for siting the power plant.