Download or read book The Influence of Vegetation Microbial Inoculation and Aging of Pesticide Residues on the Degradation of Atrazine and Metolachlor in Soils written by Shaohan Zhao and published by . This book was released on 2001 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: The bacteria Agrobacterium radiobacter J14a and Pseudomonas sp. strain ADP and the enzyme atrazine chlorohydrolase all had a significant effect on the degradation of atrazine in Alpha soil, a soil with a low indigenous atrazine-mineralizing population. However, inoculation with J14a did not increase the atrazine degradation in Bravo soil, a soil with a high number of indigenous atrazine-mineralizing microorganisms. This suggests that the ability of J14a to enhance the degradation of atrazine is affected by the presence of indigenous atrazine-mineralizing microorganisms. Inoculation of Pseudomonas fluorescens UA5-40 did not enhance the transformation of metolachlor in either soil. The ability of native prairie grasses, big bluestem (Andropogon gerardii), Indian grass (Sorghastrum nutans L.), and switch grass (Panicum virgatum L.), to degrade atrazine was influenced by the presence of indigenous atrazine-mineralizing microorganisms and the duration of the grasses in soil. Vegetation significantly decreased the concentration of atrazine in Alpha soil, but not in Bravo soil. The significant effect of the plants on atrazine degradation in Alpha soil only occurred 57 days after the transplanting of vegetation, but not 28 days after the transplanting of vegetation. The native prairie grasses had a significant effect on the degradation of metolachor in both soils. The degradative abilities of J14a, atrazine chlorohydrolase, ADP, and the native prairie grasses were influenced by the bioavailability of atrazine. J14a and vegetation significantly decreased the concentration of atrazine in Alpha soil when the initial concentration of atrazine was 93.3 [Mu]g g−1. However, they had no effect on the degradation of atrazine when the initial concentration of atrazine was 4.9 [Mu]g g−1. The influence of aging the atrazine-treated soil on the bioavailability of atrazine depends on the length of aging. The bioavailability of high concentration of atrazine (100 [Mu]g g−1) significantly declined after 56 days of aging compared with that without aging. However, the bioavailability of atrazine did not significantly decline when aging time increased from 6 to 68 days. Our results suggest that the bioavailability of atrazine applied at a high concentration declines more slowly than that applied at field application rate.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2002 with total page 972 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interaction of Herbicides and Soil Microorganisms written by Boyce Thompson Institute for Plant Research and published by . This book was released on 1971 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: The introduction of microorganisms with specific degradative capacities into the soil was shown to be a possible means of ridding the soil of contaminating chemicals. An investigation of the interactions of soil microorganisms and several groups of herbicidal compounds, primarily chlorinated derivatives, was made. In pure culture and in soils the addition of 2,3,5,6-tetrachloroterephthalate (DCPA) had little effect upon bacterial growth, and several microorganisms appeared to use the herbicide as a carbon source. The encouragement of the soil microflora by the addition of nutrient broths resulted in a reduction of toxicity to plants of a number of herbicides. Isopropyl N-phenylcarbamate (IPC) degrading organisms, when added to soil, accelerated the degradation of IPC and related compounds. A membrane 'biologicalilter' device for reducing waterborne biodegradable pollutants was also demonstrated using these organisms.
Download or read book American Doctoral Dissertations written by and published by . This book was released on 2001 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Environmental Toxicology and Chemistry written by and published by . This book was released on 2005 with total page 852 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Soil Persistence of Atrazine Metolachlor and Metribuzin as Influenced by Temperature Soil Moisture and Soil Characteristics written by and published by . This book was released on 1995 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describes a study conducted to: determine the kinetics of dissipation & bound residue formation of widely used pesticides (the herbicides atrazine, metolachlor, & metribuzin) in the Great Lakes area; test laboratory derived dissipation & bound residue formation data; provide decay rates & hydrologic transport parameters for soils in the Great Lakes Basin as input for simulation models; and modify the LEACHP pesticide fate & transport model to provide improved measures of pesticide dissipation kinetics. The study involved a series of experiments and field tests to determine the effect of soil structure on dissipation & bound residue formation, the kinetics of dissipation & bound residue formation in the laboratory & field, the leaching of herbicides, the release of aged residues, and water & transport parameters for use in the model. Results discussed include the variations in herbicide dissipation among different types of soils and tillage practices, the mineralization & volatilization of herbicides in the field, and the performance of the modified LEACHP model.
Download or read book Commencement written by Iowa State University and published by . This book was released on 2001 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Microbial Degradation of Atrazine in Soils written by Horace D. Skipper and published by . This book was released on 1966 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atrazine is an asymmetrical s-triazine herbicide used pre- and post-emergence for the control of weeds in many crops. Under conditions considered unfavorable for microbial activity, atrazine may persist in soils for extended periods of time. However, the significance of chemical versus microbial degradation is not known. This study was conducted to determine the significance of microbial degradation of atrazine by pure cultures and the native soil population in non-sterile soils. Isolated bacterial cultures were used to inoculate seeds in an attempt to provide protection against atrazine residues. Atrazine-treated soil was incubated at 30°C for varying periods and the subsequent loss of activity was correlated to evolution of 14CO2 from labeled-atrazine in a radiorespirometric system. Microorganisms, mostly bacteria, were isolated from a soil solution; pour plates of atrazine-treated and non-treated soil; and the rhizosphere of corn, oats, tomatoes, and soybeans. Viable cell counts were used as an index to test for the utilization of atrazine as the sole source of carbon. Eight bacterial isolates did not show an appreciable difference in cell counts with or without atrazine as the sole source of carbon. Seed inoculation with a mixture of three bacterial isolates did not increase the growth of oats grown in atrazine-treated soil as an indication of crop protection. In synthetic media bacterial cultures evolved a small amount of 14CO2 from chain-labeled atrazine during the first 24 hours and none thereafter. In sterile soil the same isolates evolved 0.4-0.7 percent of the input activity in two weeks. A mold respired 4.0 percent. No ring breakage was observed. In non-sterile soils, 1.4-1.6 percent of chain and 0.6-1.0 percent of ring-labeled atrazine was evolved in two weeks and 1.1-1.6 percent of ring-labeled hydroxyatrazine. The latter rate was 2-3 fold greater than from ring -labeled atrazine and indicated the formation of hydroxyatrazine as the rate limiting step in the dissipation of atrazine from soils. Data from the incubation experiment showed a 73 percent loss of the initial atrazine after 3-4 weeks. In a similar time period, only 2.2-2.6 percent of chain and 1.0-1.2 percent of ring-labeled atrazine was respired. Thus, the 14CO2 data did not account for the loss of atrazine and further supports the formation of hydroxyatrazine as the rate limiting step. Extraction of the soils containing labeled-atrazine showed the presence of hydroxyatrazine in non-sterile and sterile soils after two weeks. The radiorespirometric system designed for these studies is proposed as a means to obtain a relative index of the residual life of herbicides or pesticides. The 14CO2 data may be extrapolated to give an index based on microbial participation. Extraction of the soils would provide a test for possible non-toxic metabolites that may be formed via chemical reactions. Such data would be most beneficial in selecting and recommending new herbicides.
Download or read book Fate of Atrazine and Metolachlor in a Phytoremediation System written by Keri Lynn Deppe Henderson and published by . This book was released on 2004 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atrazine and metolachlor have been implicated in point-source pollution at agrochemical dealerships in the Midwest, as well as in nonpoint-source contamination of surface waters caused by runoff. Prairie grasses have been used in filter strips and are also useful for phytoremediation; however, little is known about the fate of contaminants and their metabolites within a grassed system. Effects of plant uptake on formation and fate of degradation products are not known. In this thesis, atrazine and metolachlor were evaluated individually. Each 14C-labeled herbicide was added to enclosed systems to determine the fate of the parent compound and its metabolites in soil, plant, and air. Soil was treated with 25 mg/kg 14C-labeled herbicide and allowed to age for a short period to simulate conditions that could be found at an agrochemical dealership site. Four systems were then amended with a mixture of prairie grasses, and the remaining four chambers were unvegetated controls. Dissipation of each herbicide and distribution of parent compound and metabolites were recorded for 21 days for 14C-atrazine and 90 days for 14C-metolachlor. 14C-CO2 and volatile 14C-organic metabolites were collected throughout the study. After the testing period, soil and plant materials were evaluated for radioactivity, and identity of metabolites was determined. Mass balance of atrazine for both vegetated and control systems was>76%, with 40% of the applied radioactivity remaining bound to soil particles after a sequential extraction technique. Parent atrazine was the dominant compound detected, with major metabolites in soil being deethylatrazine and didealkylatrazine. Less than 0.5% of applied 14C-residue was taken up by the grasses. Approximately 2% of total applied 14C-atrazine was mineralized to 14C-CO2, with no differences between vegetated and unvegetated systems. Mass balance for metolachlor was>92% for both vegetated and control systems. Vegetation decreased the amount of metolachlor in soil, with significantly higher concentrations of the metabolites metolachlor ethane sulfonic acid and the morpholinone metabolite present in vegetated soil compared to unvegetated soil. Over 7% of applied radioactivity was taken up into plant tissue during the 97-day study, thus indicating that plant uptake plays a major role in the phytoremediation of metolachlor.
Download or read book Biosciences written by and published by . This book was released on 2006 with total page 964 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bioremediation of Agricultural Soils written by Juan C. Sanchez-Hernandez and published by CRC Press. This book was released on 2019-03-14 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt: The quality of agricultural soils are always under threat from chemical contaminants, which ultimately affect the productivity and safety of crops. Besides agrochemicals, a new generation of substances invades the soil through irrigation with reclaimed wastewater and pollutants of organic origin such as sewage sludge or cattle manure. Emerging pollutants such as pharmaceuticals, nanomaterials and microplastics are now present in agricultural soils, but the understanding of their impact on soil quality is still limited. With focus on in situ bioremediation, this book provides an exhaustive analysis of the current biological methodologies for recovering polluted agricultural soils as well as monitoring the effectiveness of bioremediation.
Download or read book Bibliography of Agriculture written by and published by . This book was released on 1991-04 with total page 558 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Environmental Benefits of Conservation on Cropland written by Max Schnepf and published by . This book was released on 2007 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Glyphosate Resistance in Crops and Weeds written by Vijay K. Nandula and published by John Wiley & Sons. This book was released on 2010-12-28 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: New technologies are becoming available for managing glyphosate resistant (GR) weeds and reducing their spread. GR crop technology has revolutionized crop production in the developed world and the benefits are gradually spilling over to the developing world. In order to sustain an effective, environmentally safe herbicide such as glyphosate and the GR crop technology well in to the future, it is imperative that the issue of GR weeds be comprehensively understood. This book provides such an essential, up-to-date source of information on glyphosate resistance for researchers, extension workers, land managers, government personnel, and other decision makers. Provides comprehensive coverage of the intensely studied topic of glyphosate resistant (GR) in crops Details the development of glyphosate resistance and how to detect and manage the problem in crops Helps standardize global approaches to glyphosate resistance Encompasses interdisciplinary approaches in chemistry, weed science, biochemistry, plant physiology, plant biotechnology, genetics, ecology Includes a chapter on economic analysis of GR impact on crops
Download or read book Plant Microbes Symbiosis Applied Facets written by Naveen Kumar Arora and published by Springer. This book was released on 2014-10-30 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plants form mutualistic association with various microorganisms, particularly in the rhizosphere region. The association benefits both the partners in a number of ways. A single plant can support the growth of diverse microbes and in reciprocation these microbes help the plant in several ways. A great deal of knowledge is now available on the mechanisms of action of plant growth promoting microbes in forming association with their partner plant and benefitting it. With ever increasing population and to achieve food security it has become utmost necessary to utilize these friendly microbes to enhance the crop yield and quality in an ecofriendly and sustainable manner. We already know about the huge negative impact of chemicals used in agriculture on the humans and the ecosystems as whole. ‘Plant Microbes Symbiosis – Applied Facets’ provides a comprehensive knowledge on practical, functional and purposeful utility of plant-microbe interactions. The book reviews the utilization of beneficial microbes for crop yield enhancement and protection against diseases caused by phytopathogens and nutrient deficiencies. The tome also reviews the utility of plant growth promoting microbes in helping the plants to deal with abiotic stresses imposed by climate change and anthropogenic activities. The book showcases how plant-microbe interactions are or can be utilized for reclamation of stressed soils and degradation of pollutants in a most effective and environment friendly manner. It also ascertains the reasons for the below par performance of the microbial based inoculants. The utilization of biotechnological tools for development of next generation bioformulations to combat the new challenges and overcome past hurdles has been discussed. This wonderful association between plants and microbes if used properly will not only enhance the crop yields and reclaim barren lands but also make our planet a better place to live on for all of its habitants.
Download or read book Toxicological Profile for Strontium written by and published by . This book was released on 2004 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Pentachlorophenol Hazards to Fish Wildlife and Invertebrates written by Ronald Eisler and published by . This book was released on 1989 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:
