Laboratory and field evaluation of crystallized DOW 704 oil on the performance of the Well Impactor Ninety-Six fFine particulate matter fractionator

Subsequent to the 1997 promulgation of the Federal Reference Method (FRM) for monitoring fine particulate matter (PM2.5) in ambient air, U.S. Environmental Protection Agency (EPA) received reports that the DOW 704 diffusion oil used in the method's Well Impactor Ninety-Six (WINS) fractionator would occasionally crystallize during field use, particularly under wintertime conditions. Although the frequency of occurrence on a nationwide basis was low, uncertainties existed as to whether crystallization of the DOW 704 oil may adversely affect a sampling event's data quality. In response to these concerns, EPA and the State of Connecticut Department of Environmental Protection jointly conducted a series of specialized tests to determine whether crystallized oil adversely affected the performance of the WINS fractionator. In the laboratory, an experimental setup used dry ice to artificially induce crystallization of the diffusion oil under controlled conditions. Using primary polystyrene latex calibration aerosols, standard size-selective performance tests of the WINS fractionator showed that neither the position nor the shape of the WINS particle size fractionation curve was substantially influenced by the crystallization of the DOW 704 oil. No large particle bounce from the crystallized impaction surface was observed. During wintertime field tests, crystallization of the DOW 704 oil did not adversely affect measured PM2.5 concentrations. Regression of measurements with crystallized DOW 704 versus liquid dioctyl sebacate (DOS) oil produced slope, intercept, and R2 values of 0.98, 0.1, and 0.997 microg/m3, respectively. Additional field tests validated the use of DOS as an effective impaction substrate. As a result of these laboratory and field tests, DOS oil has been approved by EPA as a substitute for DOW 704 oil. Since the field deployment of DOS oil in 2001, users of this alternative oil have not reported any operational problems associated with its use in the PM2.5 FRM. Limited field evaluation of the BGI very sharp cut cyclone indicates that it provides a viable alternative to the WINS fractionator.     

Synthesis of polyhydroxyalkanoates in municipal wastewater treatment.

Biologically derived polyesters known as polyhydroxyalkanoates (PHAs) represent a potentially "sustainable" replacement to fossil-fuel-based thermoplastics. However, current commercial practices that produce PHA with pure microbial cultures grown on renewable, but refined, feedstocks (i.e., glucose) under sterile conditions do not represent a sustainable commodity. Here, we report on PHA production with a mixed microbial consortium indigenous to an activated sludge process on carbon present in municipal wastewaters. Reactors operated under anaerobic/aerobic and aerobic-only mode and fed primary solids fermenter liquor maintained a mixed microbial consortium capable of synthesizing PHA at 10 to 25% (w/w), while reducing soluble COD by approximately 62 to 71%. More critically, an aerobic batch reactor seeded from the anaerobic/aerobic reactor and fed fermenter liquor achieved approximately 53% PHA (w/w). Results presented suggest that environmentally benign production of biodegradable polymers is feasible. We further used PHA-rich biomass to produce a natural fiber-reinforced thermoplastic composite that can be used to offset advanced wastewater treatment costs.     

Taboos and forest governance: informal protection of hot spot dry forest in southern Madagascar

In the dry forest of southern Madagascar, a region of global conservation priority, formally protected areas are nearly totally absent. We illustrate how the continued existence of unique forest habitats in the Androy region is directly dependent on informal institutions, taboos, regulating human behavior. Qualitative interviews to map and analyze the social mechanisms underlying forest protection have been combined with vegetation analyses of species diversity and composition. Of 188 forest patches, 93% were classified as protected, and in Southern Androy all remaining forest patches larger than 5 ha were protected. Eight different types of forests, with a gradient of social fencing from open access to almost complete entry prohibitions, were identified. Transgressions were well enforced with strong sanctions of significant economic as well as religious importance. Analyses of species diversity between protected and unprotected forests were complicated because of size differences and access restrictions. However, since, for example, in southern Androy >90% of the total remaining forest cover is protected through taboos, these informal institutions represent an important, and presently the only, mechanism for conservation of the highly endemic forest species. We conclude that social aspects, such as local beliefs and legitimate sanctioning systems, need to be analyzed and incorporated along with biodiversity studies for successful conservation.     

Closed cycle construction: an integrated process for the separation and reuse of C&D waste

In The Netherlands, construction and demolition (C&D) waste is already to a large extent being reused, especially the stony fraction, which is crushed and reused as a road base material. In order to increase the percentage of reuse of the total C&D waste flow to even higher levels, a new concept has been developed. In this concept, called 'Closed Cycle Construction', the processed materials are being reused at a higher quality level and the quantity of waste that has to be disposed of is minimised. For concrete and masonry, the new concept implies that the material cycle will be completely closed, and the original constituents (clay bricks, gravel, sand, cement stone) are recovered in thermal processes. The mixed C&D waste streams are separated and decontaminated. For this purpose several dry separation techniques are being developed. The quality of the stony fraction is improved so much, that this fraction can be reused as an aggregate in concrete. The new concept has several benefits from a sustainability point of view, namely less energy consumption, less carbon dioxide emission, less waste production and less land use (for excavation and disposal sites). One of the most remarkable benefits of the new concept is that the thermal process steps are fuelled with the combustible fraction of the C&D waste itself. Economically the new process is more or less comparable with the current way of processing C&D waste. On the basis of the positive results of a feasibility study, currently a pilot and demonstration project is being carried out. The aim is to optimise the different process steps of the Closed Cycle Construction process on a laboratory scale, and then to verify them on a large scale. The results of the project are promising, so far.     

Management options and effects on a marine ecosystem: assessing the future of the Baltic

We are using the coupled models in a decision support system, Nest, to evaluate the response of the marine ecosystem to changes in external loads through various management options. The models address all the seven major marine basins and the entire drainage basin of the Baltic Sea. A series of future scenarios have been developed, in close collaboration with the Helsinki Commission, to see the possible effects of improved wastewater treatment and manure handling, phosphorus-free detergents, and less intensive land use and live stocks. Improved wastewater treatment and the use of phosphorus-free detergents in the entire region would drastically decrease phosphorus loads and improve the marine environment, particularly the occurrence of cyanobacterial blooms. However, the Baltic Sea will remain eutrophic, and to reduce other effects, a substantial reduction of nitrogen emissions must be implemented. This can only be obtained in these scenarios by drastically changing land use. In a final scenario, we have turned 50% of all agricultural lands into grasslands, together with efficient wastewater treatments and a ban of phosphorus in detergents. This scenario will substantially reduce primary production and the extension of hypoxic bottoms, increase water transparency in the most eutrophied basins, and virtually eliminate extensive cyanobacterial blooms.     

Development and verification of a toxicokinetic model of polychlorinated biphenyl elimination in persons working in a contaminated building

BACKGROUND: Polychlorinated biphenyls are toxic and slowly degrading substances that have been in widespread industrial use in the 1960s and 1970s. Despite a worldwide reduction, environmental exposure remains an issue; the assessment of an individual's level of exposure at a given time in retrospect requires valid toxicokinetic modeling of the different PCB congeners. OBJECTIVES: To develop and verify a toxicokinetic model of the in vivo-degradation of PCB 28 and 52 in adult humans. METHODS: The plasma concentrations of PCB congeners were measured in 583 persons working in a contaminated building for an average of 14.7+/-9.6 years. The values were adapted to a simple pharmacokinetic model (yt = y0 x (1 - e(-kt))); the steady state concentration y0 was estimated based on the median values of persons working exposed more than 10 years. RESULTS: The steady state concentration of PCB 28 was 0.10 microg/l, that of PCB 52 0.02 microg/l. The half-life of the congeners was estimated based on a logarithmic regression analysis according to the model mentioned above; it was 2.18 (95% CI: 1.91-2.54) years for PCB 28 and 3.95 (95% CI: 3.55-4.45) years for PCB 52, respectively. Stepwise elimination of persons with very long employment duration did not reduce the estimated half-life. CONCLUSIONS: The estimated half-life is higher than previously published data especially for PCB 52. Possible reasons and implications of this finding are discussed.     

Enhanced phytoremediation of arsenic contaminated land

In an attempt to clean up arsenic (As) contaminated soil, the effects of phosphorus (P) fertilizer and rhizosphere microbes on arsenic accumulation by the silverback fern, Pityrogramma calomelanos, were investigated in both greenhouse and field experiments. Field experiments were conducted in Ron Phibun District, an As-contaminated area in Thailand. Soil (136-269 microg As g(-1)) was collected there and used in the greenhouse experiment. Rhizosphere microbes (bacteria and fungi) were isolated from roots of P. calomelanos growing in Ron Phibun District. The results showed that P-fertilizer significantly increased plant biomass and As accumulation of the experimental P. calomelanos. Rhizobacteria increased significantly the biomass and As content of the test plants. Thus, P-fertilizer and rhizosphere bacteria enhanced As-phytoextraction. In contrast, rhizofungi reduced significantly As concentration in plants but increased plant biomass. Therefore, rhizosphere fungi exerted their effects on phytostabilization.     

Kinetic and adsorption study of acid dye removal using activated carbon

The adsorption of three acid dyes, Acid Red 97, Acid Orange 61 and Acid Brown 425 onto activated carbon was studied for the removal of acid dyes from aqueous solutions at room temperature (25 degrees C). The adsorption of each dye with respect to contact time was then measured to provide information about the adsorption characteristics of activated carbon. The rates of adsorption were found to conform to the pseudo-second-order kinetics with a good correlation. The experimental isotherms obtained, except for Acid Orange 61 studied in mixture, were of the S-type in terms of the classification of Giles and co-workers. The best fit of the adsorption isotherm data was obtained using the Freundlich model. When a comparative study was made of the results obtained with single and mixed dyes, it can be seen that some of them affect others and modify their behavior in the adsorption process. The results indicate that activated carbon could be employed for the removal of dyes from wastewater.     

Contaminant exposure in terrestrial vertebrates

Here we review mechanisms and factors influencing contaminant exposure among terrestrial vertebrate wildlife. There exists a complex mixture of biotic and abiotic factors that dictate potential for contaminant exposure among terrestrial and semi-terrestrial vertebrates. Chemical fate and transport in the environment determine contaminant bioaccessibility. Species-specific natural history characteristics and behavioral traits then play significant roles in the likelihood that exposure pathways, from source to receptor, are complete. Detailed knowledge of natural history traits of receptors considered in conjunction with the knowledge of contaminant behavior and distribution on a site are critical when assessing and quantifying exposure. We review limitations in our understanding of elements of exposure and the unique aspects of exposure associated with terrestrial and semi-terrestrial taxa. We provide insight on taxa-specific traits that contribute, or limit exposure to, transport phenomenon that influence exposure throughout terrestrial systems, novel contaminants, bioavailability, exposure data analysis, and uncertainty associated with exposure in wildlife risk assessments. Lastly, we identify areas related to exposure among terrestrial and semi-terrestrial organisms that warrant additional research.     

Relative influence of the dissolved humic material on the solid-phase extraction efficiency of pesticides from environmental water

The effect of organic matter on the solid-phase extraction (SPE) efficiency for pesticides belonging to different chemical groups (urea-derivatives, carbamates and triazines) and having different polarities, was simultaneously studied for the first time in pure and simulated water samples. SPE was carried out in precolumns packed with C18 silica or styrene-divinylbenzene copolymer PLRP-S phases on-line coupled to high performance liquid chromatography (HPLC) analysis. Retention factors in water (k'(W)) were estimated for 25 compounds and used for the calculation of the theoretical breakthrough volume (Vb(T)) in pure water. Experimental breakthrough volumes (Vb(E)) were first determined using purified and deionized water as the matrix for selected compounds having Vb(T) < 500 mL; then, the same water with an added humic acid sodium salt (HA) at 0.4-5.6 mg/L of dissolved organic carbon (DOC) content, was used as the matrix for compounds having VbE < 500 mL in pure water. Several polar pesticides showed negative linear or logarithmic Vb(E) curves depending on HA content; their recoveries were also determined in environmental samples having low dissolved organic carbon values, between 0.5-6.4 mg/L. A similar behavior was observed for these compounds in simulated and natural water samples, where DOC concentration and the percolated volume (Vp) mainly determine the solute recoveries values. However, the variation of recoveries as a function of DOC content could be negative or null depending on the two examined conditions (Vp lower or larger than Vb(E) in pure water). Results demonstrated that breakthrough volume must always be considered to correctly interpret the participation of dissolved humic material on the SPE efficiency of organic micropollutants in water.