Source identification of personal exposure to fine particulate matter using organic tracers

Personal exposure to fine particulate matter (PM2.5) is due to both indoor and outdoor sources. Contributions of sources to personal exposure can be quite different from those observed at ambient sampling locations. The primary goal of this study was to investigate the effectiveness of using trace organic speciation data to help identify sources influencing PM2.5 exposure concentrations. Sixty-four 24-h PM2.5 samples were obtained on seven different subjects in and around Boulder, CO. The exposure samples were analyzed for PM2.5 mass, elemental and organic carbon, organic tracer compounds, water-soluble metals, ammonia, and nitrate. This study is the first to measure a broad distribution of organic tracer compounds in PM2.5 personal samples. PM2.5 mass exposure concentrations averaged 8.4 μg m^?3. Organic carbon was the dominant constituent of the PM2.5 mass. Forty-four organic species and 19 water-soluble metals were quantifiable in more than half of the samples. Fifty-four organic species and 16 water-soluble metals had measurement signal-to-noise ratios larger than two after blank subtraction.The dataset was analyzed by Principal Component Analysis (PCA) to determine the factors that account for the greatest variance. Eight significant factors were identified; each factor was matched to its likely source based primarily on the marker species that loaded the factor. The results were consistent with the expectation that multiple marker species for the same source loaded the same factor. Meat cooking was an important source of variability. The factor that represents meat cooking was highly correlated with organic carbon concentrations (r = 0.84). The correlation between ambient PM2.5 and PM2.5 exposure was relatively weak (r = 0.15). Time participants spent performing various activities was generally not well correlated with PCA factor scores, likely because activity duration does not measure emissions intensity. The PCA results demonstrate that organic tracers can aid in identifying factors that influence personal exposures to PM2.5.     

Quantifying the sources of ozone, fine particulate matter, and regional haze in the Southeastern United States

A detailed sensitivity analysis was conducted to quantify the contributions of various emission sources to ozone (O₃), fine particulate matter (PM_2.5), and regional haze in the Southeastern United States. O₃ and particulate matter (PM) levels were estimated using the Community Multiscale Air Quality (CMAQ) modeling system and light extinction values were calculated from modeled PM concentrations. First, the base case was established using the emission projections for the year 2009. Then, in each model run, SO₂, primary carbon (PC), NH₃, NO_x or VOC emissions from a particular source category in a certain geographic area were reduced by 30% and the responses were determined by calculating the difference between the results of the reduced emission case and the base case.The sensitivity of summertime O₃ to VOC emissions is small in the Southeast and ground-level NO_x controls are generally more beneficial than elevated NO_x controls (per unit mass of emissions reduced). SO₂ emission reduction is the most beneficial control strategy in reducing summertime PM_2.5 levels and improving visibility in the Southeast and electric generating utilities are the single largest source of SO₂. Controlling PC emissions can be very effective locally, especially in winter. Reducing NH₃ emissions is an effective strategy to reduce wintertime ammonium nitrate (NO₃NH₄) levels and improve visibility; NO_x emissions reductions are not as effective. The results presented here will help the development of specific emission control strategies for future attainment of the National Ambient Air Quality Standards in the region.     

The design of water markets when instream flows have value

The main objective of this paper is to design and test a decentralized exchange mechanism that generates the location-specific pricing necessary to achieve efficient allocations in the presence of instream flow values. Although a market-oriented approach has the potential to improve upon traditional command and control regulations, questions remain about how these rights-based institutions can be implemented such that the potential gains from liberalized trade can be realized. This article uses laboratory experiments to test three different water market institutions designed to incorporate instream flow values into the allocation mechanism through active participation of an environmental trader. The smart, computer-coordinated market described herein offers the potential to significantly reduce coordination problems and transaction costs associated with finding mutually beneficial trades that satisfy environmental constraints. We find that direct environmental participation in the market can achieve highly efficient and stable outcomes, although the potential does exist for the environmental agent to influence outcomes.     

Natural Resource Assessment: An Approach to Science Based Planning in National Parks

We conducted a natural resource assessment at two national parks, New River Gorge National River and Shenandoah National Park, to help meet the goals of the Natural Resource Challenge—a program to help strengthen natural resource management at national parks. We met this challenge by synthesizing and interpreting natural resource information for planning purposes and we identified information gaps and natural significance of resources. We identified a variety of natural resources at both parks as being globally and/or nationally significant, including large expanses of unfragmented, mixed-mesophytic forests that qualify for wilderness protection, rare plant communities, diverse assemblages of neotropical migratory birds and salamanders, and outstanding aquatic recreational resources. In addition, these parks function, in part, as ecological reserves for plants in and wildlife. With these significant natural resources in mind, we also developed a suite of natural resource management recommendations in light of increasing threats from within and outside park boundaries. We hope that our approach can provide a blueprint for natural resource conservation at publically owned lands.     

Influence of Habitat Patchiness on Genetic Diversity and Spatial Structure of a Serpentine Endemic Plant

Abstract: Conservation of rare plant species often involves small, local populations dispersed within apparently suitable habitat. We used enzyme electrophoresis to study genotypic diversity in 32 populations of Calystegia collina , a self-incompatible clonal plant endemic to serpentine substrate in northern California's Coast Range. Genotypic diversity within a population was a good predictor of seed set by randomly marked flowers. Ramets from the most abundant genotypes in a population were most likely to produce flowers, but flowers from abundant genotypes were less likely to produce seed capsules than were flowers from rarer genotypes. These results are consistent with previous findings that reproductive success in C. collina is limited by the availability of compatible pollen. On small serpentine outcrops supporting only one or two populations, C. collina did not show reduced genotypic diversity or heterozygosity compared with populations on large outcrops supporting many populations. Instead, genotypic diversity and outcrop size had strong but independent influences on reproductive success. Although large serpentine outcrops contain more populations and provide better conditions for flower and seed production, significant diversity of unique genotypes clearly exists in isolated serpentine outcrops. Our findings suggest that plant conservation strategies must take into account the natural distribution of populations. The effects of habitat fragmentation on C. collina and other plant species that occur naturally in small, discrete patches may be unlike those that have been documented in more recently fragmented species.     

Demography of the California Condor: Implications for Reestablishment

Abstract: The remnant wild population of California Condors ( Gymnogyps californianus ) of the 1980s exhibited a rapid population decline caused by high mortality rates among adult and immature birds. The most prominent mortality factor was lead poisoning resulting from ingestion of bullet fragments in carcasses. Successful captive breeding has allowed many birds to be released to the wild since 1992, based originally on an assumption that exposure to lead could be prevented by food subsidy. The mortality of released birds, however, has generally exceeded levels needed for population stability calculated from simple population models. Collision with overhead wires was the most frequent cause of death in releases before 1994. Lead poisoning again surfaced as a problem starting in 1997 as older birds began feeding on carcasses outside the subsidy program. Although poisonings have been treated successfully by chelation therapy in recaptured birds, food subsidy is proving an ineffective solution to lead exposure. The best long-term solution appears to be either the creation of large reserves where hunting is prohibited or the restriction of hunting to nontoxic ammunition in release areas. Until sources of lead contamination are effectively countered, releases cannot be expected to result in viable populations. In addition, problems involving human-oriented behavior have resulted in the permanent removal of many released birds from the wild. The most promising reduction in human-oriented behavior has been achieved in one release of aversively conditioned, parent-reared birds. Rigorous evaluation of the factors reducing attraction to humans and human structures has been hampered by confounding of techniques in releases. Behavioral problems could be more quickly overcome by adoption of a comprehensive experimental approach.     

Status of Aquatic Bioassessment in U.S. EPA Region IX

U.S. EPA Region IX is supporting bioassessment programs in Arizona, California, Hawaii and Nevada using biocriteria program and Regional Environmental Monitoring and Assessment Program (R-EMAP) resources. These programs are designed to improve the state, tribal and regional ability to determine the status of water quality. Biocriteria program funds were used to coordinate with Arizona, California and Hawaii which resulted in these states establishing reference conditions and in developing biological indices. U.S. EPA Region IX has initiated R-EMAP projects in California and Nevada. These U.S. EPA Region IX sponsored programs have provided an opportunity to interact with the States and provide them with technical and management support. In Arizona, several projects are being conducted to develop the State's bioassessment program. These include the development of a rotational random monitoring program; a regional reference approach for macroinvertebrate bioassessments; ecoregion approach to testing and adoption of an alternate regional classification system; and development of warm-water and cold-water indices of biological integrity. The indices are projected to be used in the Arizona Department of Environmental Quality (ADEQ) 2000 water quality assessment report. In California, an Index of Biological Integrity (IBI) has been developed for the Russian River Watershed using resources from U.S. EPA's Non-point Source (NPS) Program grants. A regional IBI is under development for certain water bodies in the San Diego Regional Water Quality Control Board. Resources from the U.S. EPA Biocriteria program are being used to support the California Aquatic Bioassessment Workgroup (CABW) in conjunction with the California Department of Fish & Game (CDFG), and to support the Hawaii Department of Health (DoH) Bioassessment Program to refine biological metrics. In Nevada, R-EMAP resources are being used to create a baseline of aquatic information for the Humboldt River watershed. U.S. EPA Region IX is presently working with the Nevada Division of Environmental Protection (NDEP) to establish a Nevada Aquatic Bioassessment Workgroup. Future R-EMAP studies will occur in the Calleguas Creek watershed in Southern California, and in the Muddy and Virgin River watersheds in southern Nevada, and the Walker River watershed in eastern California and west-central Nevada.     

Geographic Analysis of Species Richness and Community Attributes of Forest Birds from Survey Data in the Mid-Atlantic Integrated Assessment Region

Species richness of local communities is a state variable commonly used in community ecology and conservation biology. Investigation of spatial and temporal variations in richness and identification of factors associated with these variations form a basis for specifying management plans, evaluating these plans, and for testing hypotheses of theoretical interest. However, estimation of species richness is not trivial: species can be missed by investigators during sampling sessions. Sampling artifacts can lead to erroneous conclusions on spatial and temporal variation in species richness. Here we use data from the North American Breeding Bird Survey to estimate parameters describing the state of bird communities in the Mid-Atlantic Assessment (MAIA) region: species richness, extinction probability, turnover and relative species richness. We use a recently developed approach to estimation of species richness and related parameters that does not require the assumption that all the species are detected during sampling efforts. The information presented here is intended to visualize the state of bird communities in the MAIA region. We provide information on 1975 and 1990. We also quantified the changes between these years. We summarized and mapped the community attributes at a scale of management interest (watershed units).     

Lead forms in urban turfgrass and forest soils as related to organic matter content and pH

Identification of reference streams and human disturbance gradients are crucial steps in assessing the effects of human disturbances on stream health. We describe a process for identifying reference stream reaches and assessing disturbance gradients using readily available, geo-referenced stream and human disturbance databases. We demonstrate the utility of this process by applying it to wadeable streams in Michigan, USA, and use it to identify which human disturbances have the greatest impact on streams. Approximately 38% of cold-water and 16% of warm-water streams in Michigan were identified as being in least-disturbed condition. Conversely, approximately 3% of cold-water and 4% of warm-water streams were moderately to severely disturbed by landscape human disturbances. Anthropogenic disturbances that had the greatest impact on moderately to severely disturbed streams were nutrient loading and percent urban land use within network watersheds. Our process for assessing stream health represents a significant advantage over other routinely used methods. It uses inter-confluence stream reaches as an assessment unit, permits the evaluation of stream health across large regions, and yields an overall disturbance index that is a weighted sum of multiple disturbance factors. The robustness of our approach is linked to the scale of disturbances that affect a stream; it will be less robust for identifying less degraded or reference streams with localized human disturbances. With improved availability of high-resolution disturbance datasets, this approach will provide a more complete picture of reference stream reaches and factors contributing to degradation of stream health.     

Estimation of required monitoring time for obtaining validation data in enclosed spaces

Methods for estimating airborne contaminant concentrations at specific locations within enclosed spaces, such as mathematical models and computational fluid dynamics (CFD), often are validated against directly measured concentrations. However, concentration variation with time introduces uncertainty into the measured concentration. Failure to determine monitoring time requirements can lead to errors in quantifying representative concentrations, which are likely to be attributed to errors in the method being validated. In the current study, to obtain the representative concentrations at multiple locations with a direct reading instrument, we used the standard deviation ratio (SDR) method to determine the required minimum monitoring time within a specified precision limit. To demonstrate the use of the SDR approach in constructing precision confidence intervals, tracer gas concentrations at nine sampling locations in an experimental room were measured to obtain population parameters. Three flow rates of 0.9, 3.3 and 5.5 m(3) min(-1) were employed and contaminant concentrations were measured using a photoionization analyser. Monitoring time requirements varied substantially with location within the room and were strongly dependent upon the flow rate of air through the room. The proposed method would be very useful for industrial hygienists and indoor air researchers who sometimes need to obtain several hundred measured concentrations for validation purposes or to perform tests under repeatable conditions in enclosed spaces. This study also showed that the proposed method can be used to devise efficient indoor monitoring strategies.