Association of benzo(a)pyrene with dissolved organic matter: Prediction of Kdom from structural and chemical properties of the organic matter

The affinity of dissolved organic matter (DOM) for binding a polycyclic aromatic hydrocarbon, benzo(a)pyrene (BaP), was measured for 11 surface and ground waters and a commercial humic acid. The hydrophobic-acid (HbA) and hydrophobic-neutral (HbN) compositions of the DOM, solution absorptivity at 270nm (ABS₂₇₀), and DOM molar volumes were determined. Waters enriched in HbA material had a larger molar volume and higher aromatic content (as indicated by the ABS₂₇₀). There was a good correlation between the size and HbA content of the DOM from the different sources and the K_dom for binding BaP. An excellent predictive relationship (r² = 0.9) was demonstrated between the ABS₂₇₀ of a water and the K_dom for binding BaP. Based on these results, it is suggested that binding of BaP to DOM depends not only on the hydrophobicity of DOM, but also on the existence of an open structure within the DOM to provide access of the aqueous solute to hydrophobic domains within the DOM.     

The effect of metal catalysts on the formation of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran precursors

The catalytic effects of copper and iron compounds were examined for their behavior in promoting formation of chlorine (Cl₂), the major chlorinating agent of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), in an environment simulating that of municipal waste fly ash. Formation of Cl₂ occurred as a result of a metal-catalyzed reaction of HCl with O₂. Catalytic activity was greatest at a temperature of approximately 400 °C, supporting a theory of de novo synthesis of PCDDs and PCDFs on fly ash particles downstream of waste combustion.     

Effect of chromium on the fatty acid composition of two strains of Euglena gracilis

The effect of hexavalent chromium on fatty acid composition was studied in two strains of Euglena gracilis; UTEX 753 (from the Culture Collection of Algae of Texas University, USA) and MAT (isolated from a highly polluted River). Both were grown in photoauxotrophic and photoheterotrophic conditions and exposed to two metal concentrations, one below and one above IC50. The high malondialdehyde (MDA) levels (3 to 7-fold) obtained with chromium concentration above IC50, suggested the existence of metal-induced lipid peroxidation. Total lipid content increased only with concentration below IC50, whereas it was inhibited by higher metal concentration. Photoheterotrophic control strains exhibited a significantly higher proportion of saturated and polyunsaturated fatty acids. Polyunsaturated acids were most affected by chromium, especially those related to chloroplast structures. Ultra-structure studies showed clear thylakoid disorganization in all treated cells. The results indicate that hexavalent chromium affects levels of fatty acids, especially those related to photosynthetic activity.     

Histological examination of sublethal effects of diazinon on ovary of bluegill,Lepomis macrochirus

The effects of the insecticide, diazinon (an organophosphorous compound), on the ovaries of bluegill (Lepomis macrohirus) were studied. Histological preparations of bluegill ovarian tissue was examined at 24, 48, 72 and 96 h and 1, 2 and 3 weeks following exposure to sublethal doses of diazinon (60 microg/l). The control contained primary follicles with an intact ovigerous lamellae and tunica albuginea. The control also revealed well developed stage IV oocytes with properly distributed provitelline nucleoli. After 24 h of exposure to diazinon, primary follicles began to show adhesion and cytoplasmic retraction in oocyte II occured. Cytoplasmic degeneration and additional adhesion and more retraction were visible at 48 h in oocyte II; 72 h brought forth adhesion, retraction and cytoplamic expulsion from oocyte IV. The number of atretic oocytes increased. Damages to the oocyte IV started to occur after 72 h of exposure. Cytoplasmic retraction and clumping was more visible at 96 h in oocyte IV. Partial destruction of the ovigerous lamellae and vitellogenic membrane occurred after 1 week. Two weeks continued to reveal destruction of follicles. Severe damage of the ovigerous lamellae, increased intrafollicular spaces, vacuolated cytoplasm, extrusion of karyoplasm and necrosis in the cytoplasm were most evident following 3 weeks of exposure. The ovarian wall became frayed and broken. Additionally, a marked increase of atretic follicles, shrinkage, and embedded nucleoli into the surrounding cytoplasm in oocyte II, III and IV were observed at week 3. This study revealed that oocytes at their different stages of maturation get affected differently at various exposure. Based on observations of the ovarian tissue compositional and structural changes following given exposure times, it becomes evident that consistent sublethal doses of diazinon can and will alter microscopic anatomy of the fish ovary.     

Real-time indoor and outdoor measurements of black carbon in an occupied house: an examination of sources

Black carbon (BC) was measured every 5 min for two years (May 1998-May 2000) inside and immediately outside a northern Virginia house (suburban Washington, DC) occupied by two nonsmokers. Two aethalometers, which measure BC by optical transmission through a quartz fiber tape, were employed indoors and outdoors. Meteorological parameters were obtained on an hourly basis from nearby Dulles airport. Indoor activities were recorded to identify indoor sources such as combustion activities, which occurred 9% of the time during the first year and 4% of the time during the second year. At times without indoor sources, indoor/outdoor BC ratios averaged 0.53 in the first year and 0.35 in the second year. The main outdoor source of BC was the general regional background, contributing 83-84% of the total during each of the two years. Morning rush hour traffic contributed 8-9% of the total BC. An evening peak in the fall and winter, thought to include contributions from wood burning, was responsible for approximately 8% of the annual average BC concentration. The main indoor sources of BC were cooking and candle burning, contributing 16 and 31%, respectively, of the annual average indoor concentrations in the two years. Relative humidity (RH) affected the outdoor aethalometer in both years. An artifact associated with the tape advance was noted for the aethalometer, but a correction factor was developed that reduced the associated error by a factor of 2.     

Assessing demineralization treatments for PVC effluent reuse in the resin polymerization step

To reduce fresh water consumption in a polyvinyl chloride (PVC) plant, the effluent from a biological treatment must be demineralized to be re-used in the resin polymerization process. Demineralization is a critical process, since the quality and the stability of the PVC resins are highly influenced by the water quality used in the process. The main target values for water parameters are the following: conductivity <10 μScm^?1, TOC < 10 mg L^?1, and Al < 0.1 mg L^?1. To achieve this quality, several reverse osmosis membranes from different materials and suppliers were tested and compared in the demineralization treatment. Polyamide membranes showed higher salt rejection compared to cellulose acetate membranes yielding both types similar flux and permeability. Two-pass reverse osmosis treatment was necessary to reach conductivities lower than 10 μS cm^?1. On the other hand, a good quality effluent for reuse was obtained by combining RO and ionic exchange resins. Results showed that good quality PVC resins in terms of color, granulometry, porosity, and bulk density were obtained when demineralized water from two-pass reverse osmosis was used as fresh water, proving the feasibility of the effluent reuse in the PVC industry.     

From food to pest: Conversion factors determine switches between ecosystem services and disservices

Ecosystem research focuses on goods and services, thereby ascribing beneficial values to the ecosystems. Depending on the context, however, outputs from ecosystems can be both positive and negative. We examined how provisioning services of wild animals and plants can switch between being services and disservices. We studied agricultural communities in Laos to illustrate when and why these switches take place. Government restrictions on land use combined with economic and cultural changes have created perceptions of rodents and plants as problem species in some communities. In other communities that are maintaining shifting cultivation practices, the very same taxa were perceived as beneficial. We propose conversion factors that in a given context can determine where an individual taxon is located along a spectrum from ecosystem service to disservice, when, and for whom. We argue that the omission of disservices in ecosystem service accounts may lead governments to direct investments at inappropriate targets.

     

EuroBionet: a pan-European biomonitoring network for urban air quality assessment

EuroBionet, the 'European Network for the Assessment of Air Quality by the Use of Bioindicator Plants', is an EU-funded cooperative project currently consisting of public authorities and scientific institutes from 12 cities in 8 countries. In 2000, the bioindicator plants tobacco (Nicotiana tabacum Bel W3), poplar (Populus nigra 'Brandaris'), spiderwort (Tradescantia sp. clone 4430), Italian rye grass (Lolium multiflorum italicum) and curly kale (Brassica oleracea acephala) were exposed to ambient air at 90 monitoring sites according to standardised methods. Visible injuries and growth parameters were assessed and the accumulation of toxic substances in leaves determined. The exposure of tobacco resulted in a gradient with low levels of ozone-induced foliar injury in N and NW Europe, and medium to high values in the southern and central regions. The results of heavy metal and sulphur analyses in rye grass samples generally showed low to very low sulphur and low to medium heavy metal concentrations in leaves. In some cities, however, local hot spots of heavy metal contamination were detected. Analyses of the PAH contents in curly kale leaves gave low to medium values, with locally elevated levels at traffic-exposed sites.     

Development of a new scale to measure subjective career success: A mixed‐methods study

Career success is a main focus of career scholars as well as organizational stakeholders. Historically, career success has been conceptualized and measured in an objective manner, mainly as salary, rank, or number of promotions. However, the changing nature of work has also necessitated a change in the way many employees view success, adding a more subjective component. Although there has been theoretical discussion and calls to develop a comprehensive measure of subjective career success, no contemporary comprehensive quantitative measure exists. The goal of this study was to create and validate a measure of subjective career success, titled the Subjective Career Success Inventory (SCSI). The SCSI includes 24 items that address subjective career success via eight dimensions. The scale was developed and validated through four phases of data collection, beginning with interviews and focus groups, followed by item sorting tasks, then item refinement through confirmatory factor analysis, and finally convergent and discriminant validity quantitative analysis. Theoretical and practical implications are discussed. Copyright © 2015 John Wiley & Sons, Ltd.     

Multi-GCM projections of future drought and climate variability indicators for the Mediterranean region

Future climate conditions for the Mediterranean region based on an ensemble of 16 Global Climate Models are expressed and mapped using three approaches, giving special attention to the intermodel uncertainty. (1) The scenarios of mean seasonal temperature and precipitation agree with the projections published previously by other authors. The results show an increase in temperature in all seasons and for all parts of the Mediterranean with good intermodel agreement. Precipitation is projected to decrease in all parts and all seasons (most significantly in summer) except for the northernmost parts in winter. The intermodel agreement for the precipitation changes is lower than for temperature. (2) Changes in drought conditions are represented using the Palmer Drought Severity Index and its intermediate Z-index product. The results indicate a significant decrease in soil moisture in all seasons, with the most significant decrease occurring in summer. The displayed changes exhibit high intermodel agreement. (3) The climate change scenarios are defined in terms of the changes in parameters of the stochastic daily weather generator calibrated with the modeled daily data; the emphasis is put on the parameters, which affect the diurnal and interdiurnal variability in weather series. These scenarios indicate a trend toward more extreme weather in the Mediterranean. Temperature maxima will increase not only because of an overall rise in temperature means, but partly (in some areas) because of increases in temperature variability and daily temperature range. Increased mean daily precipitation sums on wet days occurring in some seasons, and some parts of the Mediterranean may imply higher daily precipitation extremes, and decreased probability of wet day occurrence will imply longer drought spells all across the Mediterranean.