Degradation of ethylenethiourea pesticide metabolite from water by photocatalytic processes

In this study, photocatalytic (photo-Fenton and H₂O₂/UV) and dark Fenton processes were used to remove ethylenethiourea (ETU) from water. The experiments were conducted in a photo-reactor with an 80 W mercury vapor lamp. The mineralization of ETU was determined by total organic carbon analysis, and ETU degradation was qualitatively monitored by the reduction of UV absorbance at 232 nm. A higher mineralization efficiency was obtained by using the photo-peroxidation process (UV/H₂O₂). Approximately 77% of ETU was mineralized within 120 min of the reaction using [H₂O₂]₀ = 400 mg L^?1. The photo-Fenton process mineralized 70% of the ETU with [H₂O₂]₀ = 800 mg L^?1 and [Fe²⁺] = 400 mg L^?1, and there is evidence that hydrogen peroxide was the limiting reagent in the reaction because it was rapidly consumed. Moreover, increasing the concentration of H₂O₂ from 800 mg L^?1 to 1200 mg L^?1 did not enhance the degradation of ETU. Kinetics studies revealed that the pseudo-second-order model best fit the experimental conditions. The k values for the UV/H₂O₂ and photo-Fenton processes were determined to be 6.2 × 10^?4 mg L^?1 min^?1 and 7.7 × 10^?4 mg L^?1 min^?1, respectively. The mineralization of ETU in the absence of hydrogen peroxide has led to the conclusion that ETU transformation products are susceptible to photolysis by UV light. These are promising results for further research. The processes that were investigated can be used to remove pesticide metabolites from drinking water sources and wastewater in developing countries.     

Ozone Air Quality over North America: Part I—A Review of Reported Trends

ABSTRACT

Ozone and precursor trends can be used to measure the effectiveness of regulatory programs that have been implemented. In this paper, we review trends in the concentrations of O₃, NO_x, and HCs over North America that have been reported in the literature. Although most existing trend studies are confounded by meteorological variability, both the raw data trends and the trends adjusted for meteorology collectively indicate a general decreasing trend in O concentrations in most areas of the United States during 1985-1996. In Canada, mean daily maximum 1-hr O₃ concentrations at urban sites show mixed trends with a majority of sites showing an increase from 1980 to 1993. Mean daily maximum 1-hr O₃ at most regionally representative Canadian sites appears to decrease from 1985 to 1993 or shows no significant change. There are far fewer data and analyses of NO_x and HC trends. Available studies covering various ranges of years indicate decreases in ambient NO_x and HC concentrations in Los Angeles, CA, decreases in HC concentrations in northeastern U.S. cities, and decreases in NO concentrations in Canadian cities. Two key needs are long-term HC and NO_x measurements, particularly at rural sites, and a systematic comparison of trend detection techniques on a reference data set.     

Diplomacy for science: strategies to promote international collaboration

Technology innovation is an increasingly globalized exercise with dramatic consequences for scientific and diplomatic goals alike, and requires enhanced participation and integration of scientists and science-minded diplomats within diplomatic missions to advance shared policy goals. This more general problem is addressed in the present article by focusing on recent collaborations between U.S. and German scientists, including several of the coauthors.     

Multi-criteria risk management with the use of <Emphasis Type="Italic">DecernsMCDA</Emphasis>: methods and case studies

Emerging challenges of risk management, environmental protection, and land-use planning requires integration of stakeholder values and expert judgment. The process of decision making in situation of high uncertainty can be assisted through the use of decision support systems (DSSs). Such DSSs are often based on tools for spatial data representation (GIS) and environmental models that are integrated using multi-criteria decision analysis (MCDA). This paper presents DecernsMCDA implementing all major types of multi-criteria methods and tools (AHP, MAUT, Outranking) under the same user interface. In addition to providing ability for testing model uncertainty associated with selection of specific MCDA algorithms, DecernsMCDA implements new algorithms for parameter uncertainty analysis based on probabilistic approaches and fuzzy sets. The paper illustrates application of DecernsMCDA for selecting remedial alternative at radiologically contaminated sites.     

Acid–base physiology response to ocean acidification of two ecologically and economically important holothuroids from contrasting habitats,Holothuria scabra and Holothuria parva

Sea cucumbers are dominant invertebrates in several ecosystems such as coral reefs, seagrass meadows and mangroves. As bioturbators, they have an important ecological role in making available calcium carbonate and nutrients to the rest of the community. However, due to their commercial value, they face overexploitation in the natural environment. On top of that, occurring ocean acidification could impact these organisms, considered sensitive as echinoderms are osmoconformers, high-magnesium calcite producers and have a low metabolism. As a first investigation of the impact of ocean acidification on sea cucumbers, we tested the impact of short-term (6 to 12 days) exposure to ocean acidification (seawater pH 7.7 and 7.4) on two sea cucumbers collected in SW Madagascar, Holothuria scabra, a high commercial value species living in the seagrass meadows, and H. parva, inhabiting the mangroves. The former lives in a habitat with moderate fluctuations of seawater chemistry (driven by day–night differences) while the second lives in a highly variable intertidal environment. In both species, pH of the coelomic fluid was significantly negatively affected by reduced seawater pH, with a pronounced extracellular acidosis in individuals maintained at pH 7.7 and 7.4. This acidosis was due to an increased dissolved inorganic carbon content and pCO₂ of the coelomic fluid, indicating a limited diffusion of the CO₂ towards the external medium. However, respiration and ammonium excretion rates were not affected. No evidence of accumulation of bicarbonate was observed to buffer the coelomic fluid pH. If this acidosis stays uncompensated for when facing long-term exposure, other processes could be affected in both species, eventually leading to impacts on their ecological role.     

Spatiotemporal Modeling of Ambient Sulfur Dioxide Concentrations in Rural Western Canada

The provinces of Saskatchewan, Alberta, and British Columbia are major oil- and gas-producing regions in western Canada. With increasing oil and gas production activities, there has been a growing concern of the effect of oil and gas industry emissions on health. Nevertheless, lack of proper tools to estimate the exposure to these emissions has been a hindrance to epidemiological studies and risk assessment. This paper presents a spatiotemporal modeling approach to estimating ambient sulfur dioxide (SO₂) levels based on environmental monitoring data (N = 10,295), which were collected at rural sites (591 per month on average) of this region from June 1, 2001 to May 31, 2002. Based on the model, illustrative maps consistently revealed high and low SO₂ concentration sub-regions. The sub-regions with elevated SO₂ concentrations had increased levels during the winter months from December 2001 to March 2002 and then decreased during the spring of 2002. This statistical modeling approach may help researchers estimate the SO₂ levels within the study area for their epidemiological studies or risk assessment.     

Engineering meets institutions: an interdisciplinary approach to the management of resilience

Resilience management stretches across the decoupled domains of community, corporate, and public governance. As a result, fostering resilience needs a governance structure that supports collective actions and integrates fragmented fields with different institutional frameworks. In this study, we carry out a review of three different perspectives on resilience -engineering, social, and organizational- in order to explore resilience management in the context of governance of infrastructure systems. We discuss the common practices to address resilience of engineering systems, the need and current trend for integration of institutions into these practices through formal (e.g., policies and regulations) as well as informal mechanisms (e.g., trust, norms, and shared cognitive structures). To illustrate our theorizing, we provide three illustrative case studies. The cases highlight the barriers and enablers across the three perspectives and highlight the inter-organizational context of management of resilience. We uncovered organizational dynamics such as the necessity of establishing critical functionality through organizational capacity for stakeholder engagement, the need for diverse organizations to address institutional complexity in management of resilience, and the importance of decoupling in aligning the outcomes of resilience management practices with policies. We suggest an agenda for future research on managing practices associated with management of resilience.