Determination of levoglucosan and its isomers in size fractions of aerosol standard reference materials

The present study tested the extraction efficiency and quantification reproducibility of anhydrosugars in a series of NIST SRMs using two extraction protocols and isotopically-labeled (d₇-levoglucosan) vs. chemically analogous (sedoheptulosan) surrogates. In both instances, levoglucosan concentrations in the different versions of the Washington, D.C. urban dust standard (SRM 1649, 1649a, 1649b, and RM 8785) were similar. The present test also showed that levoglucosan concentrations were not affected by long-term shelf storage of dry material. Variability of analyses were similar for both surrogates and averaged <5%. Surrogate recoveries were shown to average 103 ± 7% and 97 ± 7% for d₇-levoglucosan and sedoheptulosan, respectively. The choice of solvent was shown to affect recoveries the most (but not variability). Levoglucosan concentrations were either seriously underestimated or overestimated with ethyl acetate extraction when d₇-levoglucosan or sedoheptulosan was used as surrogate, respectively. These results point to the need to use some fraction of polar solvent (i.e. methanol) in the solvent mixture. Anhydrosugar concentrations in the urban dust from the Czech Republic (candidate SRMs 2786 and 2787) were characterized by 3- to 7-fold higher anhydrosugar concentrations than those observed in the Washington, D.C. urban dust. The internal anhydrosugar signatures (i.e. levoglucosan/mannosan ratio: L/M) confirm the predominance of biomass combustion sources in both SRM series with mixed inputs from hardwood and softwood combustion in the Washington, D.C. urban dust and a predominantly softwood source in the Prague urban dust. The uniform distribution of anhydrosugars, across the particle size distribution of both SRM series, confirms earlier studies that low temperature charred materials contribute significant inputs to atmospheric ultrafine particles with long atmospheric residence time and transport ranges.     

Mechanochemistry of ibuprofen pharmaceutical

In this paper mechanochemistry has been studied in view of possible application to detoxification of expired pharmaceuticals. The experiments have been carried out with a commercial medication containing ibuprofen ((RS)-2-(4-(2-methylpropyl)phenyl)propanoic acid) which has been submitted to prolonged milling up to 40 h. When Al(OH)₃ is used as co-reagent, the first degradation step induced by the mechanochemical treatment is an acid-base reaction with the ibuprofen carboxylic acid group. The subsequent degradation follows a complex pathway leading to 1-(4-isobutylphenyl)ethanone, 1-isobutyl-4-vinylbenzene and 2-(4-(3-methylbutan-2-yl)phenyl)propan-1-ol after 10 h milling and, in addition, 1-(4-acetylphenyl)-2-methylpropan-1-one, 1-(4-(1-hydroxy-2-methylpropyl)phenyl)ethanone and 1-(4-(2-hydroxy-2-methylpropyl)phenyl)ethanone after 40 h milling. The degradation reaction path and products have been identified by means of FT-IR spectroscopy, thin layer chromatography, NMR spectroscopy, mass spectroscopy and elemental analysis. The observed ibuprofen decarboxylation makes the drug simultaneously lose both its pharmaceutical activity and toxicity.     

Partitioning Gas Tracer Tests for Measurement of Water in Municipal Solid Waste

Abstract

A key component in the operation of almost all bioreactor landfills is the addition of water to maintain optimal moisture conditions. To determine how much water is needed and where to add it, in situ methods are required to measure water within solid waste. Existing technologies often result in measurements of unknown accuracy, because of the variability of solid waste materials and time-dependent changes in packing density, both of which influence most measurement methods. To overcome these problems, a new technology recently developed by hydrologists for measuring water in the vadose zone—the partitioning gas tracer test—was tested. In this technology, the transport behavior of two gas tracers within solid waste is used to measure the fraction of the void space filled with water. One tracer is conservative and does not react with solids or liquids, while a second tracer partitions into the water and is separated from the conservative tracer during transport. This technology was tested in four different solid waste packings and was capable of determining the volumetric water content to within 48% of actual values, with most measurement errors less than 15%. This technology and the factors that affect its applicability to landfills are discussed in this paper.     

Fate of high loads of ammonia in a pond and wetland downstream from a hazardous waste disposal site

Halls Brook (eastern Massachusetts, USA) is a significant source of total dissolved ammonia (sum of NH(3) and NH(4)(+); (NH(3))(T)) to the Aberjona River, a water body listed for NH(3) impairment on the Clean Water Act section 303(d) list. We hypothesized (1) that (NH(3))(T) in Halls Brook derived from a hazardous waste site via groundwater discharging to a two-basin pond that feeds the brook; and (2) that transport of (NH(3))(T) to the Aberjona River was controlled by lacustrine and wetland processes. To test these hypotheses we measured (NH(3))(T) levels in the brook, the pond, and a wetlands directly downstream of the pond during both dry and wet weather over a ten month period. In addition, we analyzed sediment cores and nitrogen isotopes, and performed mass balance calculations. Groundwater discharge from beneath the hazardous waste site was the major source of (NH(3))(T) (20-67 kg d(-1)) and salinity to the north basin of the pond. The salty bottom waters of the north basin were anoxic on all sampling dates, and exhibited relatively stable (NH(3))(T) concentrations between 200 and 600 mg Nl(-1). These levels were >100-times higher than typical background levels, and 8-24-times above the acute effects level for (NH(3))(T) toxicity. Bottom waters from the north basin continuously spill over into the south basin contributing approximately 50% of the (NH(3))(T) load entering this basin. The remainder comes from Halls Brook, which receives (NH(3))(T) loadings from as yet unknown sources upstream. During storm events up to 50% of the mass of (NH(3))(T) was flushed from the south basin and into the wetlands. The wetlands acted as a (NH(3))(T) sink in dry weather in the growing season and a discharge-dependent (NH(3))(T) source to the Aberjona River during rainstorms.     

Maternal exposure to polybrominated and polychlorinated biphenyls: infant birth weight and gestational age

Understanding the influence of maternal exposures on gestational age and birth weight is essential given that pre-term and/or low birth weight infants are at risk for increased mortality and morbidity. We performed a retrospective analysis of a cohort exposed to polybrominated biphenyls (PBB) through accidental contamination of cattle feed and polychlorinated biphenyls (PCB) through residual contamination in the geographic region. Our study population consisted of 444 mothers and their 899 infants born between 1975 and 1997. Using restricted maximum likelihood estimation, no significant association was found between estimated maternal serum PBB at conception or enrollment PCB levels and gestational age or infant birth weight in unadjusted models or in models that adjusted for maternal age, smoking, parity, infant gender, and decade of birth. For enrollment maternal serum PBB, no association was observed for gestational age. However, a negative association with high levels of enrollment maternal serum PBB and birth weight was suggested. We also examined the birth weight and gestational age among offspring of women with the highest (10%) PBB or PCB exposure, and observed no significant association. Because brominated compounds are currently used in consumer products and therefore, are increasingly prevalent in the environment, additional research is needed to better understand the potential relationship between in utero exposure to brominated compounds and adverse health outcomes.     

The effect of nitrogen additions on oak foliage and herbivore communities at sites with high and low atmospheric pollution

To evaluate plant and herbivore responses to nitrogen we conducted a fertilization study at a low and high pollution site in the mixed conifer forests surrounding Los Angeles, California. Contrary to expectations, discriminant function analysis of oak herbivore communities showed significant response to N fertilization when atmospheric deposition was high, but not when atmospheric deposition was low. We hypothesize that longer-term fertilization treatments are needed at the low pollution site before foliar N nutrition increases sufficiently to affect herbivore communities. At the high pollution site, fertilization was also associated with increased catkin production and higher densities of a byturid beetle that feeds on the catkins of oak. Leaf nitrogen and nitrate were significantly higher at the high pollution site compared to the low pollution site. Foliar nitrate concentrations were positively correlated with abundance of sucking insects, leafrollers and plutellids in all three years of the study.     

Modelling heavy metal fluxes from traffic into the environment

A new method is presented which allows emissions of traffic into the environment to be described as a function of road distance. The method distinguishes different types of emissions (runoff, spray and drift), which are determined by measurements and mass balances of a specified road section. The measurement of two-dimensional pollutant concentrations in the road shoulder is an important part of the method. In a case study performed at Burgdorf, Switzerland, the method was applied to the determination of the spatial distribution of heavy metal emissions. The results show that between 36 and 65% of the heavy metals Cd, Cr, Cu, Pb and Zn are present in runoff and spray and between 35 and 64% are dispersed diffusely in the environment (defined as drift). The runoff infiltrates into the vegetated road shoulder up to a distance of approx. 1 m from the road. The distribution of spray shows a maximum at 1 m and decreases steadily up to a distance of 5 m. This information can serve as a basis for the quantitative evaluation of road-runoff treatment scenarios. Although the results of the Burgdorf study are case-specific, several general guidelines for the reduction of traffic-related emissions can be derived from it.     

Innovative approach and design for environmental protection from arising threats

Environmental Science and Pollution Research -     

Detecting changes in insect herbivore communities along a pollution gradient

The forests surrounding the urban areas of the Los Angeles basin are impacted by ozone and nitrogen pollutants arising from urban areas. We examined changes in the herbivore communities of three prominent plant species (ponderosa pine, California black oak and bracken fern) at six sites along an air pollution gradient. Insects were extracted from foliage samples collected in spring, as foliage reached full expansion. Community differences were evaluated using total herbivore abundance, richness, Shannon-Weiner diversity, and discriminant function analysis. Even without conspicuous changes in total numbers, diversity or richness of herbivores, herbivore groups showed patterns of change that followed the air pollution gradient that were apparent through discriminant function analysis. For bracken fern and oak, chewing insects were more dominant at high pollution sites. Oak herbivore communities showed the strongest effect. These changes in herbivore communities may affect nutrient cycling in forest systems.