U.S. National PM2.5 Chemical Speciation Monitoring Networks—CSN and IMPROVE: Description of networks

The U.S. Environmental Protection Agency (EPA) initiated the national PM_2.5 Chemical Speciation Monitoring Network (CSN) in 2000 to support evaluation of long-term trends and to better quantify the impact of sources on particulate matter (PM) concentrations in the size range below 2.5 μm aerodynamic diameter (PM_2.5; fine particles). The network peaked at more than 260 sites in 2005. In response to the 1999 Regional Haze Rule and the need to better understand the regional transport of PM, EPA also augmented the long-existing Interagency Monitoring of Protected Visual Environments (IMPROVE) visibility monitoring network in 2000, adding nearly 100 additional IMPROVE sites in rural Class 1 Areas across the country. Both networks measure the major chemical components of PM_2.5 using historically accepted filter-based methods. Components measured by both networks include major anions, carbonaceous material, and a series of trace elements. CSN also measures ammonium and other cations directly, whereas IMPROVE estimates ammonium assuming complete neutralization of the measured sulfate and nitrate. IMPROVE also measures chloride and nitrite. In general, the field and laboratory approaches used in the two networks are similar; however, there are numerous, often subtle differences in sampling and chemical analysis methods, shipping, and quality control practices. These could potentially affect merging the two data sets when used to understand better the impact of sources on PM concentrations and the regional nature and long-range transport of PM_2.5. This paper describes, for the first time in the peer-reviewed literature, these networks as they have existed since 2000, outlines differences in field and laboratory approaches, provides a summary of the analytical parameters that address data uncertainty, and summarizes major network changes since the inception of CSN.

ImplicationsTwo long-term chemical speciation particle monitoring networks have operated simultaneously in the United States since 2001, when the EPA began regular operations of its PM_2.5 Chemical Speciation Monitoring Network (IMPROVE began in 1988). These networks use similar field sampling and analytical methods, but there are numerous, often subtle differences in equipment and methodologies that can affect the results. This paper describes these networks since 2000 (inception of CSN) and their differences, and summarizes the analytical parameters that address data uncertainty, providing researchers and policymakers with background information they may need (e.g., for 2018 PM_2.5 designation and State Implementation Plan process; McCarthy, 2013) to assess results from each network and decide how these data sets can be mutually employed for enhanced analyses. Changes in CSN and IMPROVE that have occurred over the years also are described.     

Speciation of Arsenic in Ambient Aerosols Collected in Los Angeles

First-time measurements of the potentially toxic inorganic species of arsenic (arsenite arid arsenate) have been obtained in fine (<2.5 µm AD) and coarse (>2.5 µm AD) atmospheric particles in the Los Angeles area. A recently developed method that includes procedures for sample collection, preparation, and analysis was used in this study. Size-fractlonated aerosol samples were collected with a high-volume dichotomous virtual impactor that employed polytetrafluoroethylene filters. Results were obtained for the recovery of arsenic standards added to unexposed and collected filters. Data from this study, indicated that the recently developed speciation method can be used to determine concentrations of As(lll) and As(V) In atmospheric particulate matter samples.

Size-fractionated aerosol samples were collected in the city of Industry during January and February 1987. In most samples, As(lll) and As( V) were above the detection limit (approximately 1 ng m^-3 of either species) in both aerosol size fractions. A greater portion (about 75 percent) of the two species were observed in the fine particles. The As(lll)/As(V) ratio for both particle sizes was close to 1 (I.e., an equal mixture of both species). Comparison of total suspended particulate arsenic measured by the speciation method to that measured by a routine California Air Resources Board-approved procedure showed good agreement (r = 0.94), indicating both methods were approximately equivalent for the collection and analysis of aerosol arsenic.     

Regional Photochemical Measurement and Modeling Studies: A Summary of the Air & Waste Management Association International Specialty Conference

Abstract

This paper summarizes the Air & Waste Management Association’s International Specialty Conference, "Regional Photochemical Measurement and Modeling Studies," held in San Diego, California, on November 8-12,1993. The purpose of the conference was to facilitate exchange of information and to initiate better communication and interaction among scientists, air quality managers, regulators, and others involved in or applying tools (models and measurements to support the modeling efforts) that can be used to develop equitable and effective emissions management practices for attainment of ozone standards. Attendees heard more than 350 presentations from authors representing nearly 30 air quality and meteorological measurement and modeling studies from 18 countries. While the primary emphasis of the conference was technical, two policy sessions were included (Plenary and Concluding Sessions) to place the technical results in perspective with the policy issues. The technical agenda was divided into three subjects: Analysis of Field Measurements (results and interpretation), Modeling (status and results), and Other Topics. Papers presented at the conference are being published in a variety of journals or books to meet the needs of the scientific and policy communities. A complete bibliographical listing of the papers presented at the conference is included with this paper.

An unexpected outcome of the conference has been the development of an initiative for continuing the intercomparison of goals and scientific findings from regional air quality studies in Europe and North America, entitled “Regional Oxidants Programs Intercomparison” (ROxPIn). This paper will also discuss the goals and objectives of ROxPIn.     

Objectives and Design of Central California's 1995 Integrated Monitoring Study of the California Regional PM10/PM2.5 Air Quality Study

ABSTRACT

The 1995 Integrated Monitoring Study (IMS95) is part of the Phase 1 planning efforts for the California Regional PM_10/PM_2.5 Air Quality Study. Thus, the overall objectives of IMS95 are to (1) fill information gaps needed for planning an effective field program later this decade; (2) develop an improved conceptual model for pollution buildup (PM10, PM2.5, and aerosol precursors) in the San Joaquin Valley; (3) develop a uniform air quality, meteorological, and emissions database that can be used to perform initial evaluations of aerosol and fog air quality models; and (4) provide early products that can be used to help with the development of State Implementation Plans for PM_10. Consideration of the new particulate matter standards were also included in the planning and design of IMS95, although they were proposed standards when IMS95 was in the planning process.     

Species-specific effects of elevated ozone on wetland plants and decomposition processes

Seven species from two contrasting wetlands, an upland bog and a lowland rich fen in North Wales, UK, were exposed to elevated ozone (150 ppb for 5 days and 20 ppb for 2 days per week) or low ozone (20 ppb) for four weeks in solardomes. The rich fen species were: Molinia caerulea, Juncus subnodulosus, Potentilla erecta and Hydrocotyle vulgaris and the bog species were: Carex echinata, Potentilla erecta and Festuca rubra. Senescence significantly increased under elevated ozone in all seven species but only Molinia caerulea showed a reduction in biomass under elevated ozone. Decomposition rates of plants exposed to elevated ozone, as measured by carbon dioxide efflux from dried plant material inoculated with peat slurry, increased for Potentilla erecta with higher hydrolytic enzyme activities. In contrast, a decrease in enzyme activities and a non-significant decrease in carbon dioxide efflux occurred in the grasses, sedge and rush species.     

A detailed look at the three disciplines,environmental ethics,law and education to determine which plays the most critical role in environmental enhancement and protection

Campaigns to mitigate environmental degradation problems have failed in recent years due to not only the inability to identify the actual causes of the problems but also the approach followed in addressing these problems. This study gives a detailed consideration to the roles played by environmental education, ethics and law in environmental enhancement and protection with the aim of identifying the one that has made the most progress toward reducing the impact of environmental problems. Knowledge of this is necessary as it will help determine the starting point of any environmental sustainability campaign and direct efforts toward this. The findings of this study show that the importance of the three disciplines in environmental enhancement and protection cannot be over-looked, and it identifies environmental ethics as both an interconnector of the other two disciplines and the force that propels them into action.     

Within season and carry-over effects following exposure of grassland species mixtures to increasing background ozone

Few studies have investigated effects of increased background ozone in the absence of episodic peaks, despite a predicted increase throughout the northern hemisphere over the coming decades. In this study Leontodon hispidus was grown with Anthoxanthum odoratum or Dactylis glomerata and exposed in the UK to one of eight background ozone concentrations for 20 weeks in solardomes. Seasonal mean ozone concentrations ranged from 21.4 to 102.5 ppb. Ozone-induced senescence of L. hispidus was enhanced when grown with the more open canopy of A. odoratum compared to the denser growing D. glomerata. There was increased cover with increasing ozone exposure for both A. odoratum and D. glomerata, which resulted in an increase in the grass:Leontodon cover ratio in both community types. Carry-over effects of the ozone exposure were observed, including delayed winter die-back of L. hispidus and acceleration in the progression from flowers to seed-heads in the year following ozone exposure.     

Techniques for the stabilization and assessment of treated copper-, chromium-, and arsenic-contaminated soil

Remediation mainly based on excavation and burial of the contaminated soil is impractical with regard to the large numbers of sites identified as being in need of remediation. Therefore, alternative methods are needed for brownfield remediation. This study was conducted to assess a chemical stabilization procedure of CCA-contaminated soil using iron (Fe)-containing blaster sand (BS) or oxygen-scarfing granulate (OSG). The stabilization technique was assessed with regard to the feasibility of mixing ameliorants at an industrial scale and the efficiency of the stabilization under different redox conditions. The stability was investigated under natural conditions in 1-m3 lysimeters in a field experiment, and the effect of redox conditions was assessed in a laboratory experiment (10 L). The treatments with high additions of ameliorant (8% and 17%) were more successful in both the laboratory and field experiments, even though there was enough Fe on a stochiometric basis even at the lowest addition rates (0.1% and 1%). The particle size of the Fe and the mixing influenced the stabilization efficiency. The development of anaerobic conditions, simulated by water saturation, increases the fraction of arsenic (AsIII) and, consequently, As mobility. The use of high concentrations of OSG under aerobic conditions increased the concentrations of nickel (Ni) and copper (Cu) in the pore water. However, under anaerobic conditions, it decreased the As leaching compared with the untreated soil, and Ni and Cu leaching was not critical. The final destination of the treated soil should govern the amendment choice, that is, an OSG concentration of approximately 10% may be suitable if the soil is to be landfilled under anaerobic conditions. Alternatively, the soil mixed with 1% BS could be kept under aerobic conditions in a landfill cover or in situ at a brownfield site. In addition, the treatment with BS appeared to produce better effects in the long term than treatment with OSG.     

Removal of Remazol Brilliant Violet-5R dye using periwinkle shells

The purpose of this research is to obtain optimal processing conditions for the adsorption of Remazol Brilliant Violet-5R (RBV-5R) dye onto activated carbon prepared from periwinkle shells (PSAC) by chemical activation with KOH using response surface methodology. Central composite design (CCD) was used to determine the effects of three preparation variables; CO₂ activation temperature, CO₂ activation time and KOH:char impregnation ratio (IR) on two responses; percentage RBV-5R dye removal and PSAC yield. Based on the CCD, two quadratic models were developed for percentage RBV-5R dye removal and PSAC yield, respectively. The most influential factor on each experimental design response was identified from the analysis of variance (ANOVA). The optimum conditions for the adsorption of RBV-5R dye onto PSAC were CO₂ activation temperature of 811 °C, CO₂ activation time of 1.70 h and IR of 3.0, resulting in 81.28% RBV-5R dye removal and 28.18% PSAC yield. PSAC prepared under optimum conditions was mesoporous with a Brunauer–Emmett–Teller surface area of 1894 m²·g^?1, total pore volume of 1.107 cm³·g^?1 and average pore diameter of 2.32 nm. The surface morphology and functional groups of the activated carbon were respectively determined from the scanning electron microscopy and Fourier transform infrared analysis.     

Impact of water saturation level on arsenic and metal mobility in the Fe-amended soil

The impact of water saturation level (oxidizing-reducing environment) on As and metal solubility in chromium, copper, arsenic (CCA)-contaminated soil amended with Fe-containing materials was studied. The soil was mixed with 0.1 and 1 wt% of iron grit (Fe(0)) and 1, 7 and 15 wt% of oxygen scarfing granulate (OSG, a by-product of steel processing). Solubility of As and metals was evaluated by a batch leaching test and analysis of soil pore water. Soil saturation with water greatly increased As solubility in the untreated as well as in the Fe-amended soil. This was related to the reductive dissolution of Fe oxides and increased concentration of As(III) species. Fe amendments showed As reducing capacity under both oxic and anoxic conditions. The cytotoxicity of the soil pore water correlated with the concentration of As(III). The Fe-treatments as well as water saturation of soil were less significant for the solubility of Cu, Cr and Zn than for As. The batch leaching test used for waste characterization substantially underestimated As solubility that could occur under water-saturated (anaerobic) conditions. In the case of soil landfilling, other techniques than Fe-stabilization of As containing soil should be considered.