Occurrence of Volatile Organic Compounds in Aquifers of the United States1

Abstract: Samples of ambient ground water were collected during 1985‐2002 from 3,498 wells in 98 aquifer studies throughout the United States. None of the sampled wells were selected because of prior knowledge of nearby contamination. Most of these samples were analyzed for 55 volatile organic compounds (VOCs) to characterize their national occurrence. Volatile organic compounds were found in samples collected from 90 of the 98 aquifer studies. Occurrence frequencies of one or more VOCs for the 98 aquifer studies ranged from 0 to about 77% at an assessment level of 0.2 microgram per liter (μg/l). The aquifer studies with the largest occurrence frequencies were in southern Florida, southern New York, southern California, New Jersey, and Nevada. Trihalomethanes and solvents were the most frequently occurring VOC groups. Of the 55 VOCs included in this assessment, 42 occurred in at least one sample at an assessment level of 0.2 μg/l. Chloroform, perchloroethene, and methyl tert‐butyl ether were the most frequently occurring VOCs. Many factors, such as the hydrogeology of the aquifer, use of VOCs, land use, and the transport and fate properties of VOCs, affect the occurrence of VOCs in ground water.     

Toxicity of fipronil and its enantiomers to marine and freshwater non-targets

Fipronil is a phenylpyrazole insecticide used in agricultural and domestic settings for controlling various insect pests in crops, lawns, and residential structures. Fipronil is chiral; however, it is released into the environment as a racemic mixture of two enantiomers. In this study, the acute toxicity of the (S,+) and (R,-) enantiomers and the racemic mixture of fipronil were assessed using Simulium vittatum IS-7 (black fly), Xenopus laevis (African clawed frog), Procambarus clarkii (crayfish), Palaemonetes pugio (grass shrimp), Mercenaria mercenaria (hardshell clam), and Dunaliella tertiolecta (phytoplankton). Results showed that S. vittatum IS-7 was the most sensitive freshwater species to the racemic mixture of fipronil (LC50 = 0.65 microg/L) while P. pugio was the most sensitive marine species (LC50 = 0.32 microg/L). Procambarus clarkii were significantly more sensitive to the (S,+) enantiomer while larval P. pugio were significantly more sensitive to the (R,-) enantiomer. Enantioselective toxicity was not observed in the other organisms tested. Increased mortality and minimal recovery was observed in all species tested for recovery from fipronil exposure. These results indicate that the most toxic isomer of fipronil is organism-specific and that enantioselective toxicity may be more common in crustaceans than in other aquatic organisms.     

Higher education institutions,SDG2 and agri-food sustainability: lessons from Chulalongkorn University and Thailand

Environment, Development and Sustainability - This paper examines higher education efforts linking United Nations Sustainable Development Goals (UNSDGs) and agri-food system sustainability given...     

The need for formal reflexivity in conservation science

Conservation issues are often complicated by sociopolitical controversies that reflect competing philosophies and values regarding natural systems, animals, and people. Effective conservation outcomes require managers to engage myriad influences (social, cultural, political, and economic, as well as ecological). The contribution of conservation scientists who generate the information on which solutions rely is constrained if they are unable to acknowledge how personal values and disciplinary paradigms influence their research and conclusions. Conservation challenges involving controversial species provide an opportunity to reflect on the paradigms and value systems that underpin the discipline and practice of conservation science. Recent analyses highlight the ongoing reliance on normative values in conservation. We frame our discussion around controversies over feral horses (Equus ferus caballus) in the Canadian West and New Zealand and suggest that a lack of transparency and reflexivity regarding normative values continues to prevent conservation practitioners from finding resilient conservation solutions. We suggest that growing scrutiny and backlash to many normative conservation objectives necessitates formal reflexivity methods in conservation biology research, similar to those required of researchers in social science disciplines. Moreover, given that much conservation research and action continues to prioritize Western normative values regarding nature and conservation, we suggest that adopting reflexive methods more broadly is an important step toward more socially just research and practice. Formalizing such methods and requiring reflexivity in research will not only encourage reflection on how personal and disciplinary value systems influence conservation work but could more effectively engage people with diverse perspectives and values in conservation and encourage more novel and resilient conservation outcomes, particularly when dealing with controversial species.     

Larvicidal and repellent activity of N-methyl-1-adamantylamine and oleic acid a major derivative of bael tree ethanol leaf extracts against dengue mosquito vector and their biosafety on natural predator

Environmental Science and Pollution Research - Aegle marmelos (L.) Correa belongs to the family Rutaceae is generally known as “bael fruit tree” occuring across the south Asian...