Photocatalytic degradation of the herbicide cinosulfuron in aqueous TiO<Subscript>2</Subscript> suspension

The photocatalytic degradation of a sulfonylurea herbicide, cinosulfuron, has been studied in TiO₂ aqueous suspensions. A first order kinetic law was found. The influence of the initial concentration of cinosulfuron and of the initial radiant flux on the kinetics were evaluated. The identification of the intermediate products was based on high performance liquid chromatography coupled with mass spectrometry analyses (HPLC-MS). The mineralization of cinosulfuron was traced using ion chromatography and total organic carbon (TOC) measurements. These results indicate that the photocatalytic degradation of cinosulfuron leads to CO₂, NO₃ ⁻ and SO₄ ²⁻ as final products, and in addition cyanuric acid (C₃H₃O₃N₃), confirming previous results on triazinic ring-containing compounds. Electronic Publication     

Attitudes towards the conservation of biological diversity—A case study in Kristianstad Municipality,Sweden

Human actions towards land, freshwater and oceans have already caused biodiversity to decline. This study aims to investigate attitudes towards the conservation of biological biodiversity among different groups in a Swedish city, Kristianstad. An inquiry including statements measuring attitudes towards the conservation of habitats, animals and plants, to the biological diversity within selected local areas, to global and national areas, and to societal issues, was replied to by 271 persons. Deciduous forests, birds and wild flowers were given highest priority. An area categorized as wetland including lakeshore meadows with a rich bird life was prioritized as most important for conservation while a forest area was chosen as best for recreation. The experts gave lower priority to arable land, urban parks, domestic animals, agricultural and garden plants and to conifer forests compared to the other groups. Knowledge about what people in general value as important could facilitate the future planning of nature areas in the city of Kristianstad.     

Disposition and metabolic profiling of [14C]-decabromodiphenyl ether in pregnant Wistar rats

Fully brominated diphenyl ether, decabromodiphenyl ether (DBDE), is one of the most widely used brominated flame retardants worldwide. Little data is available about the metabolic fate of DBDE in animal models and nothing at all about the extent of foetal exposure. In this work, pregnant Wistar rats were force-fed with 99.8% pure [14C]-DBDE over 96 h at a late stage of gestation (days 16 to 19). More than 19% of the administered dose was recovered in tissues and carcasses, demonstrating efficient absorption of DBDE despite its high molecular weight and low solubility. The highest concentrations of DBDE residues were found in endocrine glands (adrenals, ovaries) and in the liver, with lower values recorded for fat. In all tissue extracts, most of the radioactivity was associated with unchanged DBDE. The use of high-grade purity [14C]-DBDE allowed quantification of several metabolites present both in maternal tissues and in foetuses. These biotransformation products accounted for 9-27% of the extractable radioactivity in tissues and 14% of that in foetuses. Three nona-BDEs and one octa-BDE were identified by LC-APPI/MS. The unequivocal characterisation of a hydroxylated octa-BDE isolated from liver was confirmed by NMR. In rat, the main metabolic pathways of DBDE are debromination and oxidation. DBDE, and very likely most of its metabolites, are able to cross the placental barrier in rat. Metabolic profiles, obtained in vivo for the first time, demonstrated the presence of DBDE and major biotransformation products in endocrine glands as well as in foetuses. The biological activity of these metabolites still needs to be assessed in order to better understand the potential toxicity of DBDE.     

Effect of the endectocide ivermectin on filamentous fungi

We investigated the effect of ivermectin, at environmental concentrations and above, on several strains of filamentous fungi. Ivermectin did not show significant short-term effect on biomass production and germination rate of the spores. By contrast, the spore production was stimulated twofold in Phanerochaete chrysosporium and Mucor racemosus cultures, whereas that endpoint was reduced in Fusarium cultures. A long-term exposure of F. oxysporum to ivermectin reduced both production and germination of fungal spores. Ivermectin was not an inducer of exocellular oxidases.     

Measurements of personal exposure to nitrogen dioxide in four Mexican cities in 1996

Nitrogen dioxide is a ubiquitous pollutant in urban areas. Indoor NO2 concentrations are influenced by penetration of outdoor concentrations and by indoor sources. The objectives of this study were to evaluate personal exposure to NO2, taking into account human time-activity patterns in four Mexican cities. Passive filter badges were used for indoor, outdoor, and personal NO2 measurements over 48 hr and indoor workplace measurements over 16 hr. Volunteers completed a questionnaire on exposure factors and a time-activity diary during the sample period. An unpaired t test, an analysis of variance (ANOVA), and a linear regression were performed to compare differences among cities and mean personal NO2 concentrations involving housing characteristics, as well as to determine which variables predicted the personal NO2 concentration. Sampling periods were in April, May, and June 1996 in Mexico City, Guadalajara, Cuernavaca, and Monterrey. All 122 volunteers in the study were working adults, with a mean age of 34 (SD +/- 7.38); 64% were female, and the majority worked in public offices and universities. The highest NO2 concentrations were found in Mexico City (36 ppb for outdoor, 57 ppb for indoor, and 39 ppb for personal concentration) and the lowest in Monterrey (19 ppb for outdoor, 24 ppb for indoor, and 24 ppb for personal concentration). Significant differences in NO2 concentrations were found among the cities in different microenvironments. During the sampling period, volunteers spent 85% of their time indoors. The highest personal NO2 concentration was found when volunteers kept their windows closed (p = 0.03). In the regression model adjusted by city and gender, the best predictors of personal NO2 concentration were outdoor levels and time spent outdoors (R2 = 0.68). These findings suggest that outdoor NO2 concentrations were an important influence on the personal exposure to NO2, due to the specific characteristics and personal behavior of the people in these Mexican cities.     

Photochemical behavior of chlorsulfuronR in water and in adsorbed phase

The photochemistry of the herbicide chlorsulfuron^R (2-chloro-N-[[4-methoxy-6-methyl-1.3.5-triazinyl-2-amino]carbonyl]benzene sulfonamide) was investigated in methanol, distilled water, natural creek-water, on silica gel and on montmorillonit surfaces. The rate of degradation was determined in outdoor and indoor experiments simulating tropospheric conditions (λ>290 nm). Two major photoproducts were identified in all cases.     

Practical implementation of cumulative-effects management of marine ecosystems in western North America

Globally, ecosystem structure and function have been degraded by the cumulative effects (CE) of multiple stressors. To maintain ecosystem resilience, there is an urgent need to better account for CE in management decision-making at various scales. Current laws and regulations are supported by a multitude of frameworks and strategies that vary in application and terminology use across management agencies and geopolitical boundaries. We synthesized management frameworks that accounted for CE in marine ecosystems at the regional and national levels across western North America (Canada, United States, Mexico) to identify similarities and shared challenges to successful implementation. We examined examples of solutions to the identified challenges (e.g., interagency and cross-border partnerships to overcome challenges of managing for ecologically relevant spatial scales). Management frameworks in general consisted of 3 phases: scoping and structuring the system; characterizing relationships; and evaluating management options. Challenges in the robust implementation of these phases included lack of interagency coordination, minimal incorporation of diverse perspectives, and data deficiencies. Cases that provided solutions to these challenges encouraged coordination at ecological rather than jurisdictional scales, enhanced involvement of stakeholders and Indigenous groups, and used nontraditional data sources for decision-making. Broader implementation of these approaches, combined with increased interagency and international coordination and collaboration, should facilitate the rapid advancement of more effective CE assessment and ecosystem management in North America and elsewhere.     

Degradation of Polyethylene Designed for Agricultural Purposes

For many years now, scientific articles have been published on the potential biodegradability of polyethylene. Polyethylene (PE) with peroxidant additives, in the form of agricultural films, is sold by various suppliers as biodegradable mulch. Even though, the photo-chemical and thermal degradation of these products under artificial laboratory conditions is highlighted, several extrapolation on the biodegradation and, moreover, on the neutral environmental impact of PE are made. In this study, three different commercial mulch films have been submitted to standardised biodegradation tests and the results are discussed. The first conclusions are that a very low degree of biodegradation of the commercial PE films is achieved from these tests and that crosslinked PE micro-fragments are found in soil after a very long period of time.