Comparison of Microbial Transformation Rate Coefficients of Xenobiotic Chemicals Between Field-Collected and Laboratory Microcosm Microbiota


Book Description

Two second-order transformation rate coefficients--kb, based on total plate counts, and kA, based on periphyton-colonized surface areas--were used to compare xenobiotic chemical transformation by laboratory-developed (microcosm) and by field-collected microbiota. Similarity of transformer to nontransformer community structure in blended aufwuchs was indicated by kb values, and similarity of transformation rates per unit of periphyton-colonized surface area was indicated by kA values. Xenobiotic chemicals used for the comparisons were methyl parathion (MP), diethyl phthalate (DEP), and 2,4-dichlorophenoxyacetic acid butoxyethyl ester (2,4-DBE). Even though rate coefficients of each of the chemicals were similar among microcosm- and field-collected microbial samples, not all of the field-collected samples showed MP or DEP transformation. The MP transformation was suppressed by aqueous extracts of field-collected, algae-dominated aufwuchs. Lack of DEP transformation appeared to have resulted from an absence of DEP-transforming bacteria in field-collected aufwuchs samples.










Chemical Biomarkers in Aquatic Ecosystems


Book Description

This textbook provides a unique and thorough look at the application of chemical biomarkers to aquatic ecosystems. Defining a chemical biomarker as a compound that can be linked to particular sources of organic matter identified in the sediment record, the book indicates that the application of these biomarkers for an understanding of aquatic ecosystems consists of a biogeochemical approach that has been quite successful but underused. This book offers a wide-ranging guide to the broad diversity of these chemical biomarkers, is the first to be structured around the compounds themselves, and examines them in a connected and comprehensive way. This timely book is appropriate for advanced undergraduate and graduate students seeking training in this area; researchers in biochemistry, organic geochemistry, and biogeochemistry; researchers working on aspects of organic cycling in aquatic ecosystems; and paleoceanographers, petroleum geologists, and ecologists. Provides a guide to the broad diversity of chemical biomarkers in aquatic environments The first textbook to be structured around the compounds themselves Describes the structure, biochemical synthesis, analysis, and reactivity of each class of biomarkers Offers a selection of relevant applications to aquatic systems, including lakes, rivers, estuaries, oceans, and paleoenvironments Demonstrates the utility of using organic molecules as tracers of processes occurring in aquatic ecosystems, both modern and ancient




Xenobiotics in the Soil Environment


Book Description

This book describes the vast variety of xenobiotics, such as pesticides, antibiotics, antibiotic resistance genes, agrochemicals and other pollutants, their interactions with the soil environment, and the currently available strategies and techniques for soil decontamination and bioremediation. Topics covered include: transport mechanisms of pollutants along the Himalayas; use of earthworms in biomonitoring; metagenomic strategies for assessing contaminated sites; xenobiotics in the food chain; phyto-chemical remediation; biodegradation by fungi; and the use of enzymes and potential microbes in biotransformation. Accordingly, the book offers a valuable guide for scientists in the fields of environmental ecology, soil and food sciences, agriculture, and applied microbiology.







Bioavailability of Contaminants in Soils and Sediments


Book Description

Bioavailability refers to the extent to which humans and ecological receptors are exposed to contaminants in soil or sediment. The concept of bioavailability has recently piqued the interest of the hazardous waste industry as an important consideration in deciding how much waste to clean up. The rationale is that if contaminants in soil and sediment are not bioavailable, then more contaminant mass can be left in place without creating additional risk. A new NRC report notes that the potential for the consideration of bioavailability to influence decision-making is greatest where certain chemical, environmental, and regulatory factors align. The current use of bioavailability in risk assessment and hazardous waste cleanup regulations is demystified, and acceptable tools and models for bioavailability assessment are discussed and ranked according to seven criteria. Finally, the intimate link between bioavailability and bioremediation is explored. The report concludes with suggestions for moving bioavailability forward in the regulatory arena for both soil and sediment cleanup.




Freshwater Fungi


Book Description

The available literature on freshwater fungi is limited. Over the subsequent years a considerable volume of scientific papers have appeared scattered throughout numerous journals. There is therefore no recent synthesis of the subject and this is the objective of the proposed book. Freshwater habitats are rich in fungi with some 3,000 described species, most of papers focussing on their identification, substrata they grow on and world distribution. However, these fungi play an important role in the freshwater ecosystem, and are primarily involved in the breakdown of leaf litter contributing food for detritus feeders. Our book will bring together a wide range of acclaimed mycologists to review recent developments on the biology and ecology of freshwater fungi, particularly their molecular phylogeny, biodiversity, causative diseases of freshwater amphibians, fishes and invertebrate animals, decomposition of leaf litter, stream pollution and their potential role in bioremediation.