Loss of PM2.5 Nitrate from Filter Samples in Central California

Abstract

Evaporative loss of particulate matter (with aerodynamic diameter <2.5 μm, [PM_2.5]) ammonium nitrate from quartz-fiber filters during aerosol sampling was evaluated from December 3, 1999, through February 3, 2001, at two urban (Fresno and Bakersfield) and three nonurban (Bethel Island, Sierra Nevada Foothills, and Angiola) sites in central California. Compared with total particulate nitrate, evaporative nitrate losses ranged from <10% during cold months to >80% during warm months. In agreement with theory, evaporative loss from quartz-fiber filters in nitric acid denuded samplers is controlled by the ambient nitric acid-to-particulate nitrate ratio, which is determined mainly by ambient temperature. Accurate estimation of nitrate volatilization requires a detailed thermodynamic model and comprehensive chemical measurements. For the 14-month average of PM_2.5 acquired on Teflon-membrane filters, measured PM_2.5 mass was 8–16% lower than actual PM_2.5 mass owing to nitrate volatilization. For 24-hr samples, measured PM_2.5 was as much as 32–44% lower than actual PM_2.5 at three California Central Valley locations.     

Climate Change and Water Resources in Arid Mountains: An Example from the Bolivian Andes

Climate change is projected to have a strongly negative effect on water supplies in the arid mountains of South America, significantly impacting millions of people. As one of the poorest countries in the region, Bolivia is particularly vulnerable to such changes due to its limited capacity to adapt. Water security is threatened further by glacial recession with Bolivian glaciers losing nearly half their ice mass over the past 50 years raising serious water management concerns. This review examines current trends in water availability and glacier melt in the Bolivian Andes, assesses the driving factors of reduced water availability and identifies key gaps in our knowledge of the Andean cryosphere. The lack of research regarding permafrost water sources in the Bolivian Andes is addressed, with focus on the potential contribution to mountain water supplies provided by rock glaciers.     

Predictors of urinary bisphenol A and phthalate metabolite concentrations in Mexican children

Exposure to endocrine disrupting chemicals such as bisphenol A (BPA) and phthalates is prevalent among children and adolescents, but little is known regarding important sources of exposure at these sensitive life stages. In this study, we measured urinary concentrations of BPA and nine phthalate metabolites in 108 Mexican children aged 8–13 years. Associations of age, time of day, and questionnaire items on external environment, water use, and food container use with specific gravity-corrected urinary concentrations were assessed, as were questionnaire items concerning the use of 17 personal care products in the past 48-h. As a secondary aim, third trimester urinary concentrations were measured in 99 mothers of these children, and the relationship between specific gravity-corrected urinary concentrations at these two time points was explored. After adjusting for potential confounding by other personal care product use in the past 48-h, there were statistically significant (p < 0.05) positive associations in boys for cologne/perfume use and monoethyl phthalate (MEP), mono(3-carboxypropyl) phthalate (MCPP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), and in girls for colored cosmetics use and mono-n-butyl phthalate (MBP), mono(2-ethylhexyl) phthalate (MEHP), MEHHP, MEOHP, and mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), conditioner use and MEP, deodorant use and MEP, and other hair products use and MBP. There was a statistically significant positive trend for the number of personal care products used in the past 48-h and log-MEP in girls. However, there were no statistically significant associations between the analytes and the other questionnaire items and there were no strong correlations between the analytes measured during the third trimester and at 8–13 years of age. We demonstrated that personal care product use is associated with exposure to multiple phthalates in children. Due to rapid development, children may be susceptible to impacts from exposure to endocrine disrupting chemicals; thus, reduced or delayed use of certain personal care products among children may be warranted.     

The potential effect of differential ambient and deployment chamber temperatures on PRC derived sampling rates with polyurethane foam (PUF) passive air samplers

Performance reference compound (PRC) derived sampling rates were determined for polyurethane foam (PUF) passive air samplers in both sub-tropical and temperate locations across Australia. These estimates were on average a factor of 2.7 times higher in summer than winter. The known effects of wind speed and temperature on mass transfer coefficients could not account for this observation. Sampling rates are often derived using ambient temperatures, not the actual temperatures within deployment chambers. If deployment chamber temperatures are in fact higher than ambient temperatures, estimated sampler-air partition coefficients would be greater than actual partition coefficients resulting in an overestimation of PRC derived sampling rates. Sampling rates determined under measured ambient temperatures and estimated deployment chamber temperatures in summer ranged from 7.1 to 10 m³ day⁻¹ and 2.2-6.8 m³ day⁻¹ respectively. These results suggest that potential differences between ambient and deployment chamber temperatures should be considered when deriving PRC-based sampling rates.     

Lessons from the 2006 Louisiana health and population survey

The 2005 hurricane season caused extensive damage and induced a mass migration of approximately 1.1 million people from southern Louisiana in the United States. Current and accurate estimates of population size and demographics and an assessment of the critical needs for public services were required to guide recovery efforts. Since forecasts using pre-hurricane data may produce inaccurate estimates of the post-hurricane population, a household survey in 18 hurricane-affected parishes was conducted to provide timely and credible information on the size of these populations, their demographics and their condition. This paper describes the methods used, the challenges encountered, and the key factors for successful implementation. This post-disaster survey was unique because it identified the needs of the people in the affected parishes and quantified the number of people with these needs. Consequently, this survey established new population and health indicator baselines that otherwise would have not been available to guide the relief and recovery efforts in southern Louisiana.     

First detection of an NSAID, flunixin, in sheep's wool using GC-MS

Exposure to the nonsteroidal anti-inflammatory drug (NSAID) diclofenac resulted in the near extinction of three species of Gyps vultures on the Indian subcontinent. Other NSAIDs present in the environment, including flunixin, may pose a similar risk. In the course of a study to determine the feasibility of detecting NSAIDs in keratinous matrices (i.e., hair, nails and feathers) using GC-MS, wool opportunistically collected from a sheep treated with flunixin was analysed for residues. Flunixin was detected qualitatively in external wool wash and extract samples. While residues of veterinary agents and pesticides have previously been found in sheep’s wool, our preliminary investigation provides the first instance of an NSAID being detected in this matrix. Here we provide the sample preparation methods and GC-MS parameters used to enable further refinement as part of ongoing conservation and consumer quality control measures.     

Adsorption of Pb,Cd, Cu,Zn, and Ni to titanium dioxide nanoparticles: effect of particle size,solid concentration,and exhaustion

Purpose  

Adsorption of metals (Pb, Cd, Cu, Ni, Zn) to TiO₂ nanoparticles and bulk particles was examined for use as a contaminant removal substrate as a function of particle size, sorbent concentration, and exhaustion.     

Development and calibration of a passive sampler for N-nitrosodimethylamine (NDMA) in water

N-Nitrosamines such as N-nitrosodimethylamine (NDMA) are organic compounds of environmental concern in groundwater, wastewater and potable water due to their potent carcinogenicity in laboratory animal studies and probable human carcinogenicity. While passive sampling techniques have become a widely used tool for providing time-averaged estimates of trace pollutant concentration, for chemicals such as NDMA that have relatively high water solubility, the selection of a suitable sorbent is difficult. This work is a proof of principle study that investigated for the first time the use of coconut charcoal as a passive sampler sorbent. Apparent charcoal/water sorption coefficients for NDMA were >551 mL g⁻¹ at environmentally relevant aqueous concentrations of less than 1 μg L⁻¹. Under the experimental conditions employed, a sampling rate of 0.45 L d⁻¹ was determined and for an aqueous concentration of 1000 ng L⁻¹, it is predicted that the sampler remains in the linear uptake stage for approximately 4 d, while equilibrium attainment would require about 26 d. The presence of humic acid, used as a surrogate for DOC, enhanced NDMA sorption on the coconut charcoal.     

Child passenger restraint use and emergency department--reported injuries: a special study using the National Electronic Injury Surveillance System-All Injury Program, 2004

INTRODUCTION: In 2004, more than 180,000 child passengers aged 相似文献   

Sequestration of aristolochic acids by the pipevine swallowtail, Battus philenor (L.): evidence and ecological implications

Summary. It has long been assumed that the North American pipevine swallowtail, Battus philenor (L.) (Papilionidae, Troidini), is protected from natural enemies by aristolochic acids sequestered from its Aristolochia food plants. This study confirmed that populations of B. philenor from Virginia and east Texas sequester these compounds. A comparison of the aristolochic acid profiles of the Virginia butterflies and their A. macrophylla food plants revealed several differences. The aristolochic acid fraction of the foliage was dominated by aristolochic acids I and II, whereas the insects had a much lower proportion of aristolochic acid II and contained, in addition, substantial amounts of aristolochic acids Ia and IVa, which were not detected in the plants. The eggs, larval integument, osmeterial glands, pupal cuticle, and adults (wings and bodies) all contained aristolochic acids. These findings help explain the abundant ecological data indicating that both immature and adult B. philenor are unpalatable and protected from natural enemies. Received 7 April 2000; accepted 31 May 2000