Survey of Airborne 2,4-D in South-Central Washington

The extensive application of 2,4-D herbicides to wheat and other agricultural crops in the states of Washington and Oregon can produce "off-target" damage when the 2,4-D formulations are transported by the atmosphere to sensitive crops, such as grapes. During May-June of 1973 and April-June of 1974, a 2,4-D monitoring network in south-central Washington collected samples for subsequent herbicide analysis. The daily, 24 hr field samples were collected with differential Impactor-impinger air samplers and were routinely analyzed in the analytical laboratory by electron-capture gas chromatography. In addition, gas chromatography/mass spec-trometry was employed for positive identification of the 2,4-D esters and for comparative quantitative analysis. The complete sampling and analytical methodology, the 2,4-D concentration data for 1973 and 1974, the agricultural 2,4-D application records and crop Injury reports, and the concomitant meteorological data are described in this paper.     

High Temperature,High Pressure Electrostatic Precipitation

This paper presents the results of work conducted by Research-Cottrell under EPA contract 68-02-2104. The feasibility of electrostatic precipitation at temperatures and pressures varying from ambient condition to 1366°K and 3550 kPa, respectively, has been demonstrated in a laboratory wire-pipe electrode system. Stable corona discharges are obtained at all temperatures subject to appropriate choices of electrode dimension, polarity, and pressure. Current-voltage characteristics are reported for dry air, a simulated combustion gas, and a substitute fuel gas. The effects of temperature, pressure, electrode geometry and polarity on sparkover voltage, corona-starting voltage, and current are evaluated. A precipitator performance model is included to incorporate this data into a high temperature, high pressure precipitator design. This model has been evaluated for an electrostatic (HTHP) precipitator following a pressurized fluidized bed combustor at 1089 K and 920 kPa. It is recommended that prototype HTHP electrostatic precipitators be applied to pilot coal gasifiers and fluidized bed combustors to obtain detailed design data and to verify the accuracy of the performance model under actual operating conditions.     

Uncertainty requirements of the European Union’s Industrial Emissions Directive for monitoring sulfur dioxide emissions: Implications from a blind comparison of sulfate measurements by accredited laboratories

When annual average PM_2.5 (fine particulate matter sized 2.5 microns and less) data for 2005 became available in April 2006 and the 3-yr average PM_2.5 concentration in an area just north of the Houston Ship Channel reached 15.0 µg/m³, the Texas Commission on Environmental Quality (TCEQ) initiated daily collection of quartz fiber as well as Teflon PM_2.5 filter samples for chemical speciation analysis. The purpose of the chemical speciation analysis was to use the speciation data, together with meteorological data and hourly TEOM (tapered element oscillating microbalance) PM_2.5 mass data, to identify the causes of the high PM_2.5 concentrations affecting the monitoring site and the neighborhood. The ultimate purpose was to target emission reduction efforts to sources contributing to the high measured PM_2.5 concentrations. After a year of data collection, it was recognized that a specific source, unpaved driveways and loading areas along the Ship Channel and dirt tracked onto Clinton Drive, the main artery running east-west north of the Ship Channel, were the primary cause for the Clinton Drive site's measuring PM_2.5 concentrations significantly higher than other sites in Houston. The source characterization and remediation steps that have led to sustained reduced concentrations are described in this paper.

Implications: With PM_2.5 exceedances it can be essential to have or develop chemical speciation data as part of the process of identifying the source types causing exceedances of an annual standard. Positive matrix factorization (PMF) analysis proved to be a powerful tool that identified the two locally emitted species contributing to exceedances, which did not occur at other sites in the region. They were calcium sulfate (gypsum), an industrial by-product, and soil minerals. Other data analysis approaches were necessary to distinguish North African dust events, which PMF failed to identify.     

Degradation of ethylenethiourea pesticide metabolite from water by photocatalytic processes

In this study, photocatalytic (photo-Fenton and H₂O₂/UV) and dark Fenton processes were used to remove ethylenethiourea (ETU) from water. The experiments were conducted in a photo-reactor with an 80 W mercury vapor lamp. The mineralization of ETU was determined by total organic carbon analysis, and ETU degradation was qualitatively monitored by the reduction of UV absorbance at 232 nm. A higher mineralization efficiency was obtained by using the photo-peroxidation process (UV/H₂O₂). Approximately 77% of ETU was mineralized within 120 min of the reaction using [H₂O₂]₀ = 400 mg L^?1. The photo-Fenton process mineralized 70% of the ETU with [H₂O₂]₀ = 800 mg L^?1 and [Fe²⁺] = 400 mg L^?1, and there is evidence that hydrogen peroxide was the limiting reagent in the reaction because it was rapidly consumed. Moreover, increasing the concentration of H₂O₂ from 800 mg L^?1 to 1200 mg L^?1 did not enhance the degradation of ETU. Kinetics studies revealed that the pseudo-second-order model best fit the experimental conditions. The k values for the UV/H₂O₂ and photo-Fenton processes were determined to be 6.2 × 10^?4 mg L^?1 min^?1 and 7.7 × 10^?4 mg L^?1 min^?1, respectively. The mineralization of ETU in the absence of hydrogen peroxide has led to the conclusion that ETU transformation products are susceptible to photolysis by UV light. These are promising results for further research. The processes that were investigated can be used to remove pesticide metabolites from drinking water sources and wastewater in developing countries.     

Adapting a holistic approach to flood management in the Hawkesbury–Nepean region: complexities and perceptions of the agencies involved

This paper looks into the complexity of managing flood risks in the Hawkesbury–Nepean catchment, Australia. Several aspects are explored: (1) the complexities created by the way different agencies are involved in assessing flood risks; (2) different perceptions on acceptable flood risk level; (3) community engagement in defining acceptable flood risk level; (4) views on a holistic flood risk management plan; and (5) challenges of a centralised information system. This study concludes that the complexity of managing a large catchment is exacerbated by the difference in the way professionals perceive the problem. This has led to (1) different standards for acceptable risks; (2) inconsistent attempt to set up a regional-scale flood management plan beyond the jurisdictional boundaries; (3) absence of a regional-scale agency with licence to share and update information; and (d) lack of forums for dialogue with insurance companies to ensure an integrated approach to flood management.     

The effects of 3,3′,4,4′-tetrabromobiphenyl on rats fed diets containing a constant level of copper and varying levels of molybdenum

Copper (Cu) metabolism is altered in rats fed diets high in molybdenum (Mo) and low in Cu. This 10-week study was carried out to examine the effects of supplemental Mo (7.5–240 μg/g diet) on male Sprague–Dawley rats fed diets adequate in Cu (5 μg/g diet) and to determine the susceptibility of Mo-treated animals to the environmental pollutant 3,3′,4,4′-tetrabromobiphenyl (TBB). After 7 weeks of dietary treatment, half of the rats in each group received a single IP injection of TBB (150 μM/kg bw), while the other half received the corn oil vehicle. Rats sacrificed at 10 weeks showed no effects of Mo on growth, feed efficiency, or selected organ or tissue weights. Dose-dependent effects on plasma Mo (0–5.1 μg/mL), plasma Cu (0.95–0.20 μg/mL), and bone Cu (3.4–10 μg/g) in control through the high dose were found. Cu sequestration in the bone of Mo-treated rats is a new finding. TBB treatment resulted in dramatic weight loss and loss of absolute organ mass. Relative organ weights were increased, except for the thymus. TBB altered the concentrations of certain amino acids. Compared to control rats, this polybrominated biphenyl congener significantly decreased plasma Cu and ceruloplasmin at higher concentrations of dietary Mo and promoted the process of plasma Cu decrease by Mo, suggesting a combined effect.     

Mapping species distributions: A comparison of skilled naturalist and lay citizen science recording

To assess the ability of traditional biological recording schemes and lay citizen science approaches to gather data on species distributions and changes therein, we examined bumblebee records from the UK’s national repository (National Biodiversity Network) and from BeeWatch. The two recording approaches revealed similar relative abundances of bumblebee species but different geographical distributions. For the widespread common carder (Bombus pascuorum), traditional recording scheme data were patchy, both spatially and temporally, reflecting active record centre rather than species distribution. Lay citizen science records displayed more extensive geographic coverage, reflecting human population density, thus offering better opportunities to account for recording effort. For the rapidly spreading tree bumblebee (Bombus hypnorum), both recording approaches revealed similar distributions due to a dedicated mapping project which overcame the patchy nature of naturalist records. We recommend, where possible, complementing skilled naturalist recording with lay citizen science programmes to obtain a nation-wide capability, and stress the need for timely uploading of data to the national repository.     

Traffic and meteorological impacts on near-road air quality: summary of methods and trends from the Raleigh Near-Road Study

A growing number of epidemiological studies conducted worldwide suggest an increase in the occurrence of adverse health effects in populations living, working, or going to school near major roadways. A study was designed to assess traffic emissions impacts on air quality and particle toxicity near a heavily traveled highway. In an attempt to describe the complex mixture of pollutants and atmospheric transport mechanisms affecting pollutant dispersion in this near-highway environment, several real-time and time-integrated sampling devices measured air quality concentrations at multiple distances and heights from the road. Pollutants analyzed included U.S. Environmental Protection Agency (EPA)-regulated gases, particulate matter (coarse, fine, and ultrafine), and air toxics. Pollutant measurements were synchronized with real-time traffic and meteorological monitoring devices to provide continuous and integrated assessments of the variation of near-road air pollutant concentrations and particle toxicity with changing traffic and environmental conditions, as well as distance from the road. Measurement results demonstrated the temporal and spatial impact of traffic emissions on near-road air quality. The distribution of mobile source emitted gas and particulate pollutants under all wind and traffic conditions indicated a higher proportion of elevated concentrations near the road, suggesting elevated exposures for populations spending significant amounts of time in this microenvironment. Diurnal variations in pollutant concentrations also demonstrated the impact of traffic activity and meteorology on near-road air quality. Time-resolved measurements of multiple pollutants demonstrated that traffic emissions produced a complex mixture of criteria and air toxic pollutants in this microenvironment. These results provide a foundation for future assessments of these data to identify the relationship of traffic activity and meteorology on air quality concentrations and population exposures.