Self-Organizing Maps for Integrated Environmental Assessment of the Mid-Atlantic Region

A new method has been developed to perform environmental assessment at regional scale. This involves a combination of a self-organizing map (SOM) neural network and principal component analysis (PCA). The method is capable of clustering ecosystems in terms of environmental conditions and suggesting relative cumulative environmental impacts of multiple factors across a large region. Using data on land-cover, population, roads, streams, air pollution, and topography of the Mid-Atlantic region, the method was able to indicate areas that are in relatively poor environmental condition or vulnerable to future deterioration. Combining the strengths of SOM with those of PCA, the method offers an easy and useful way to perform a regional environmental assessment. Compared with traditional clustering and ranking approaches, the described method has considerable advantages, such as providing a valuable means for visualizing complex multidimensional environmental data at multiple scales and offering a single assessment or ranking needed for a regional environmental assessment while still facilitating the opportunity for more detailed analyses.     

Characterization of air emissions and residual ash from open burning of electronic wastes during simulated rudimentary recycling operations

Air emissions and residual ash samples were collected and analyzed during experiments of open, uncontrolled combustion of electronic waste (e-waste), simulating practices associated with rudimentary e-waste recycling operations. Circuit boards and insulated wires were handled separately to simulate processes associated with metal recovery. The average emissions of polychlorinated dibenzodioxins and dibenzofurans (PCDD/PCDFs) were 92 ng toxic equivalency (TEQ)/kg [n = 2, relative standard deviation (RSD) = 98%] and 11 900 ng TEQ/kg (n = 3, RSD = 50%) of the initial mass of the circuit boards and insulated wire, respectively. The value for the insulated wire is about 100 times higher than that for backyard barrel burning of domestic waste. The emission concentrations of polybrominated dibenzodioxins and dibenzofurans (PBDD/PBDFs) from the combustion of circuit boards were 100 times higher than for their polychlorinated counterparts. Particulate matter (PM) sampling of the fly ash emissions indicated PM emission factors of approximately 15 and 17 g/kg of the initial mass for the circuit boards and insulated wire, respectively. Fly ash samples from both types of e-waste contained considerable amounts of several metallic elements and halogens; lead concentrations were more than 200 times the United States regulatory limits for municipal waste combustors and 20 times those for secondary lead smelters. Leaching tests of the residual bottom ash showed that lead concentrations exceeded U.S. Environmental Protection Agency landfill limits, designating this ash as a hazardous waste.     

Multiobjective air pollution monitoring network design

The methodologies currently available to optimize the locations of air pollutant monitoring stations typically include a single pollutant and a single objective. In this paper, multiple objective functions are introduced that provide performance measures describing the spatial coverage of the network and its ability to detect violations of standards for multiple pollutants. An additional objective regarding the effect of data validity in the design is also considered. The objective functions are cast in a manner that permits considerable flexibility in the model formulation. The numerical difficulties associated with the formulation are discussed as are extensions of the basic framework. The basic model and its extensions have been applied to the design of a monitoring network for Tarragona, Spain.     

Simple PDF models for convectively driven vertical diffusion

The mode of vertical velocity in convective boundary layers (CBLs) is usually negative and the probability distribution function (PDF) of w, P_w, is rarely symmetric except near the top and bottom of CBLs. Consequently, vertical diffusion from elevated sources is usually asymmetric and exhibits a descending mode of concentration, causing higher peak surface concentrations than predicted by Gaussian models. The main concentration (χ) effects, we argue, can be modeled using the simplest of PDF diffusion models, with tracers responding to P_w at the source height with straight line trajectories and simple reflection at the surface and z_i, the mixing depth. The critical element is the choice of P_w. Two P_w models are offered, a bi-Gaussian (BG) and a Gaussian-ramp (GR) formulation. Both have some observational support, and the resulting PDF models are mathematically tractable. Analytical solutions for key variables are given; these show some surprising contrasts between the BG and GR models, but both can approximate laboratory and numerical modeling results for ∝χdy patterns. A diverse selection of atmospheric turbulence measurements is presented; for measures that reflect asymmetry in P_w, the data show wide ranges and do not lend support to any particular form of P_w. Recent lidar measurements of oil fog plumes are presented that show a large variability in ∝χdy patterns, even with substantial averaging periods. The only concurrent turbulence measurement that strongly correlates with the observed vertical diffusion of oil fog is the mode of wind elevation angle. A simple adaptation of the BG model is recommended that fits the average peak ∝χdy and distance of occurrence as observed so far.     

A model of wet deposition to complex terrain

A two dimensional model of the seeder-feeder mechanism of orographic rainfall enhancement has been developed. The model has been extended to include the deposition of aerosol material incorporated into the orographic feeder cloud by nucleation scavenging. Parameterizations of any changes in the concentration of SO₄²⁻ in the cloud due to chemical reactions have also been included. The model is used to predict the rainfall enhancement and SO₄²⁻ deposition over terrain consisting of two parallel ridges oriented perpendicular to the wind. A wide range of spatial scales has been used of up to 150 km. It is found that the patterns of rainfall enhancement and deposition are strongly dependent on the spatial scales, the atmospheric structure and the cloud chemistry.     

Multimedia Integrated Modeling for Environmental Protection: Introduction to a Collaborative Framework

The EPA's Office of Research and Development is embarking on a long term project to develop a Multimedia Integrated Modeling System (MIMS). The system will have capabilities to represent the transport and fate of nutrients and chemical stressors over multiple spatial and temporal scales. MIMS will be designed to improve the environmental management community's ability to evaluate the impact of air and water quality and watershed management practices on stream and estuarine conditions. The system will provide a computer-based problem-solving environment for testing understanding of multimedia (atmosphere, land, water) environmental problems, such as the movement of chemicals through the hydrologic cycle, and the response of aquatic ecological systems to land-use change, with initial emphasis on the fish health endpoint. The design will attempt to combine the state-of-the-art in computer science, system design, and numerical analysis (i.e., object-oriented design, parallel processing, advanced numerical libraries including analytic elements) with the latest advancements in process level science (hydrology, atmospheric sciences, chemistry, ecology). The purpose of this paper is to introduce a vision for a MIMS and anticipate the challenges to its development.     

Relationships between direction of wind flow and fine particle sulfur concentrations within and upwind of St Louis,MO

The relationships are considered between monthly and quarterly means of the fine particle sulfur (S) concentrations and wind flow direction, period of day and season of the year. The measurements used are those obtained at selected urban and at rural monitoring stations in the St Louis area during the Regional Air Pollution Study in 1975, 1976 and 1977. Higher mean fine particle S concentrations are observed with wind flows from the E compared to the W and from the NE and SE quadrants compared to the NW quadrant. Substantially higher fine particle S concentrations are obtained with wind flows from the E compared to the W even when conditions are selected so that the values of temperature, solar radiation intensity and wind speed are within the same restricted ranges. A consistent increase in the fine particle S concentrations occurs through the late morning and afternoon with decrease in the evening and especially in the early morning during spring and summer months with wind flows from the E.The contributions are estimated for local scale and regional scale processes to the observed fine particle S concentrations. Local scale processes include those involving atmospheric formation and primary emissions each contribute 0.6−1.0 and 0.6 μg m⁻³ of the fine particle S. Regional scale processes account for the greater part of the observed concentrations especially when the wind flows are from the SE or SW. Regional scale episodes involving passage of warm high pressure systems to the E of St Louis with accumulation of precursors made especially significant contributions to formation of fine particle S.The atmospheric gas phase and liquid phase chemical reactions contributing to the formation of fine particle S are discussed. Emphasis is placed on the effects of chemistry on the seasonal variations in concentrations of fine particle S.     

Overview of endocrine disruptor research activity in the United States.

The issue of whether environmental contaminants are inducing adverse health effects in humans and wildlife via interaction with endocrine systems has gained increasing interest during the 1990s. Endocrine disruption is one of the highest priority research topics for the US EPA, and a detailed research strategy has been developed to guide the placement of resources over the next several years. To address the deficiency of testing guidelines in detecting and characterizing damage mediated by interaction with the endocrine system, EPA has issued new multi generation testing guidelines. The new endpoints for monitoring pubertal development, semen quality, and estrous cyclicity will better enable determination of the affected sex, target organ, and life stage following exposure throughout the life cycle. Another major area of effort within EPA is the development of an endocrine disruptor screening program in response to passage of the Food Quality Protection Act of 1996. The current status of these efforts is described. On the federal level, endocrine disruption is one of the five priority research areas for the Committee on the Environment and Natural Resources (CENR) within the Executive Office of President. The CENR has developed a framework to assess research needs for endocrine disruptors, inventoried existing efforts of the federal government (nearly 400 projects were identified as active in FY96), and prioritized additional research needs based upon the needs and gaps in current efforts. It is clear that a great deal of research is underway to clarify the validity of the endocrine disruptor hypothesis and to determine the breadth of chemicals that pose a risk to the endocrine system. The degree of forward research planning and coordination across many organizations should ensure that sufficient data will be available within the next few years to allow a rigorous weight of evidence evaluation that is needed to bring together diverse types of information to make informed decisions regarding risks to humans and wildlife.