Ozone Predictions in Atlanta,Georgia: Analysis of the 1999 Ozone Season

ABSTRACT

Ozone prediction has become an important activity in many U.S. ozone nonattainment areas. In this study, we describe the ozone prediction program in the Atlanta metropolitan area and analyze the performance of this program during the 1999 ozone-forecasting season. From May to September, a team of 10 air quality regulators, meteorologists, and atmospheric scientists made a daily prediction of the next-day maximum 8-hr average ozone concentration. The daily forecast was made aided by two linear regression models, a 3-dimensional air quality model, and the no-skill ozone persistence model. The team's performance is compared with the numerical models using several numerical indicators. Our analysis indicated that (1) the team correctly predicted next-day peak ozone concentrations 84% of the time, (2) the two linear regression models had a better performance than a 3-dimensional air quality model, (3) persistence was a strong predictor of ozone concentrations with a performance of 78%, and (4) about half of the team's wrong predictions could be prevented with improved meteorological predictions.     

Chlorinated vapor intrusion indicators,tracers, and surrogates (ITS): Supplemental measurements for minimizing the number of chemical indoor air samples—Part 1: Vapor intrusion driving forces and related environmental factors

Vapor intrusion (VI) assessment is complicated by spatial and temporal variability, largely due to compounded interactions among the many individual factors that influence the vapor migration pathway from subsurface sources to indoor air. Past research on highly variable indoor air datasets demonstrates that conventional sampling schemes can result in false negative determinations of potential risk corresponding to reasonable maximum exposures (RME). While high‐frequency chemical analysis of individual chlorinated volatile organic compounds (CVOCs) in indoor air is conceptually appealing, it remains largely impractical when numerous buildings are involved and particularly for long‐term monitoring. As more is learned about the challenges with indoor air sampling for VI assessment, it has become clear that alternative approaches are needed to help guide discrete sampling efforts and reduce sampling requirements while maintaining acceptable confidence in exposure characterization. Indicators, tracers, and surrogates (ITS), which include a collection of quantifiable metrics and tools, have been suggested as a potential solution for making VI pathway assessment and long‐term monitoring more informative, efficient, and cost‐effective. This review, compilation, and evaluation of ITS demonstrates how even low numbers of indoor air CVOC samples can provide high levels of confidence for representing the RME levels (e.g., 95th percentile) often sought by regulatory agencies for less than chronic effects. A two‐part compilation of available evidence for select low‐cost ITS is presented, with Part 1 focused on introducing the concepts of ITS, meteorologically based ITS, and the evidence from data‐rich studies to support lower cost CVOC VI assessments. Part 1 includes the results of quantitative analyses on two robust residential building VI datasets, where numerous supplemental metrics were collected concurrently with indoor air concentration data. These are supplemented with additional less‐intensive studies in different circumstances. These analyses show that certain ITS metrics and tools, including differential temperature, differential pressure, and radon (in Part 2), can provide benefits to VI assessment and long‐term monitoring. This includes indicators that narrow the assessment period needed to capture RME conditions, tracers that enhance understanding of the conceptual site model, and aid in the identification of preferential pathways and surrogates that support or substitute for CVOC sampling results. The results of this review provide insight into the scientifically supportable uses of ITS.     

The horizontal reactive media treatment well (HRX Well®) for passive in situ remediation: Design,implementation, and sustainability considerations

A new in situ remediation concept termed a Horizontal Reactive Media Treatment Well (HRX Well^®) is presented that utilizes a horizontal well filled with reactive media to passively treat contaminated groundwater in situ. The approach involves the use of a large‐diameter directionally drilled horizontal well filled with solid reactive media installed parallel to the direction of groundwater flow. The engineered contrast in hydraulic conductivity between the high in‐well reactive media and the ambient aquifer hydraulic conductivity results in the passive capture, treatment, and discharge back to the aquifer of proportionally large volumes of groundwater. Capture and treatment widths of up to tens of feet can be achieved for many aquifer settings, and reductions in downgradient concentrations and contaminant mass flux are nearly immediate. Many different types of solid‐phase reactive treatment media are already available (zero valent iron, granular activated carbon, biodegradable particulate organic matter, slow‐release oxidants, ion exchange resins, zeolite, apatite, etc.). Therefore, this concept could be used to address a wide range of contaminants. Laboratory and pilot‐scale test results and numerical flow and transport model simulations are presented that validate the concept. The HRX Well can access contaminants not accessible by conventional vertical drilling and requires no aboveground treatment or footprint and requires limited ongoing maintenance. A focused feasibility evaluation and alternatives analysis highlights the potential cost and sustainability advantages of the HRX Well compared to groundwater extraction and treatment systems or funnel and gate permeable reactive barrier technologies for long‐term plume treatment. This paper also presents considerations for design and implementation for a planned upcoming field installation.     

Status and trends of circumpolar peregrine falcon and gyrfalcon populations

Ambio - The peregrine falcon (Falco peregrinus) and the gyrfalcon (Falco rusticolus) are top avian predators of Arctic ecosystems. Although existing monitoring efforts are well established for both...     

Combining GIS with fuzzy multicriteria decision-making for landfill siting in a fast-growing urban region

Landfill siting is a difficult, complex, tedious, and protracted process requiring evaluation of many different criteria. This paper presents a fuzzy multicriteria decision analysis alongside with a geospatial analysis for the selection of landfill sites. It employs a two-stage analysis synergistically to form a spatial decision support system (SDSS) for waste management in a fast-growing urban region, south Texas. The first-stage analysis makes use of the thematic maps in Geographical information system (GIS) in conjunction with environmental, biophysical, ecological, and socioeconomic variables leading to support the second-stage analysis using the fuzzy multicriteria decision-making (FMCDM) as a tool. It differs from the conventional methods of integrating GIS with MCDM for landfill selection because the approach follows two sequential steps rather than a full-integrated scheme. The case study was made for the city of Harlingen in south Texas, which is rapidly evolving into a large urban area due to its vantage position near the US-Mexico borderlands. The purpose of GIS was to perform an initial screening process to eliminate unsuitable land followed by utilization of FMCDM method to identify the most suitable site using the information provided by the regional experts with reference to five chosen criteria. Research findings show that the proposed SDSS may aid in recognizing the pros and cons of potential areas for the localization of landfill sites in any study region. Based on initial GIS screening and final FMCDM assessment, "site 1" was selected as the most suitable site for the new landfill in the suburban area of the City of Harlingen. Sensitivity analysis was performed using Monte Carlo simulation where the decision weights associated with all criteria were varied to investigate their relative impacts on the rank ordering of the potential sites in the second stage. Despite variations of the decision weights within a range of 20%, it shows that "site 1" remains its comparative advantage in the final site selection process.     

Effect of Introduced Mosquitofish on Pacific Treefrogs and the Role of Alternative Prey

Abstract: Mosquitofish ( Gambusia affinis ) are distributed by many mosquito control programs because of their broad habitat tolerance and because they are considered by some to be effective mosquito predators. As a result, mosquitofish have become established as an exotic species in numerous perennial streams in the Santa Monica Mountains within the last 10–15 years. Previous studies have found that mosquitofish prey heavily on California newt (   Taricha torosa ) larvae that inhabit mountain streams. We found Pacific treefrog (   Hyla regilla ) tadpoles in the stomachs of 65% of stream-caught mosquitofish. In both laboratory and field experiments, we found that mosquitofish preyed heavily on treefrog tadpoles, even when high densities of mosquito larvae were presented as alternative prey. Thus, despite apparent high densities of Pacific treefrog populations, our experiments suggest that introduced mosquitofish may negatively affect stream-breeding H. regilla in the Santa Monica Mountains.     

Combining Conservation and Development on Private Lands: Lessons from Costa Rica

Privately owned parks continue to attract interest across the tropics for their ability to blend biodiversity protection with sustainable development. Despite rapid proliferation of these privately owned protected areas, the conservation community knows little about them. We interviewed owners of 68 private parks in Costa Rica to learn more about their contribution to that country's national conservation effort. Key findings include: (1) the total number of private reserves is estimated to be in the vicinity of 250; (2) reserves fell into a wide variety of categories, ranging from formal parks and ecotourism reserves to biological stations and hybrid reserves; (3) total nationwide coverage is approximately 63,832 ha, or 1.2% of the national territory; (4) reserves were protecting ecologically important habitat, particularly primary rain forest; (5) reserves were owned mostly by Costa Ricans; (6) reserves were used for a wide variety of activities, especially ecotourism and for the owners' personal enjoyment; (7) reserve owners' biggest problem was poaching of mammals; (8) reserves were protecting key corridor and buffer zone areas between and around larger national parks. Results from this study should help enhance our understanding of this little-known conservation and development tool. They should be of interest wherever biodiversity remains threatened and wherever new conservation and development partners are being sought - which includes most of the developing world.     

Policies and regulations for Brazil’s artisanal gold mining sector: analysis and recommendations

In Brazil, artisanal and small-scale gold mining (ASGM) produces in the range of 6 tonnes of gold (Au) per annum, and employs approximately 200,000 people. Most of this mining activity is in the Amazon region, where miners have been extracting gold for more than 40 years. In the Tapajos River Basin, assessments indicate that around 99% of miners operate without the environmental and mining permits required by law. This is a result of a combination of unrealistic or lack of proper policies and regulations, lack of political will, lack of infra-structure to enforce the existing regulations and lack of incentives to miners to comply with legal requirements.In this article, we analyze a group of 20 laws, decrees and resolutions in Brazil, focusing on how idiosyncrasies in these regulations reveal gaps between policy and reality in ASGM areas. Artisanal miners operate in vast and remote areas and the government lacks the resources (personnel, vehicles, information and materials) to enforce the laws. Our analysis emphasizes the need for creating new government commitments and identifying priority areas where government agents can focus their efforts.There is no single solution for the environmental, health, technical and socio-economic problems associated with ASGM. However, a realistic approach should consider improving the level of education of miners, creating government programs to provide technical assistance in the field, simplifying administrative procedures and ensuring adequate measures for enforcement.     

Monitoring dissolved organic carbon in surface and drinking waters

The presence of natural organic matter (NOM) strongly impacts drinking water treatment, water quality, and water behavior during distribution. Dissolved organic carbon (DOC) concentrations were determined daily over a 22 month period in river water before and after conventional drinking water treatment using an on-line total organic carbon (TOC) analyzer. Quantitative and qualitative variations in organic matter were related to precipitation and runoff, seasons and operating conditions. Following a rainfall event, DOC levels could increase by 3.5 fold over baseflow concentrations, while color, UV absorbance values and turbidity increased by a factor of 8, 12 and 300, respectively. Treated water DOC levels were closely related to the source water quality, with an average organic matter removal of 42% after treatment.