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2007-5-5 EST最新文章和摘要
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Metabolic Footprinting: A New Approach to Identify Physiological Changes in Complex Microbial Communities upon Exposure to Toxic Chemicals Inês D. S. Henriques, Diana S. Aga, Pedro Mendes, Seamus K. O'Connor, and Nancy G. Love,* Department of Civil and Environmental Engineering, Virginia Tech, 418 Durham Hall, Blacksburg, Virginia 24061, Department of Chemistry, The State University of New York at Buffalo, 611 Natural Sciences Complex, Buffalo, New York 14260, Virginia Bioinformatics Institute, Virginia Tech, Bioinformatics Facility and Department of Biological Sciences, Virginia Tech, 2125 Derring Hall, Blacksburg, Virginia 20641 Received for review November 24, 2006 Revised manuscript received February 18, 2007 Accepted February 26, 2007 Abstract: Metabolic footprinting coupled with statistical analysis was applied to multiple, chemically stressed activated sludge cultures to identify probable biomarkers that indicate community stress. The impact of cadmium (Cd), 2,4-dinitrophenol (DNP), and N-ethyl-maleimide (NEM) shock loads on the composition of the soluble fraction of activated sludge cultures was analyzed by gross biomolecular analyses and liquid chromatography-mass spectrometry (LC-MS). Fresh mixed liquor from four distinct treatment plants was each divided in four different batches and was subjected to no chemical addition (control) and spike additions of the stressors Cd, DNP, or NEM. The results indicate that chemical stress caused a significant release of proteins, carbohydrates, and humic acids from the floc structure into the bulk liquid. Using discriminant function analysis (DFA) with genetic algorithm variable selection (GA-DFA), the samples subjected to the different stress conditions plus control could be differentiated, thereby indicating that the footprints of the soluble phase generated by LC-MS were different for the four conditions tested and, therefore, were toxin-specific but community-independent. These footprints, thus, contain information about specific biomolecular differences between the stressed samples, and we found that only a limited number of m/z (mass to charge) ratios from the mass spectra were needed to differentiate between the control and each stressed sample. Since the experiments were conducted with mixed liquor from four distinct wastewater treatment plants, the discriminant m/z ratios may potentially be used as universal stress biomarkers in activated sludge systems. -------------------------------------------------------------------------------- Leaching of Estrogenic Hormones from Manure-Treated Structured Soils Jeanne Kjær,* Preben Olsen, Kamilla Bach, Heidi C. Barlebo, Flemming Ingerslev, Martin Hansen, and Bent Halling Srensen Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen, Denmark, Faculty of Agricultural Sciences, Research Centre Foulum, University of Aarhus, DK-8830 Tjele, Denmark, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark, and Danish Environmental Protection Agency, Strandgade 29, DK-1401 Copenhagen, Denmark Received for review November 21, 2006 Revised manuscript received March 9, 2007 Accepted March 22, 2007 Abstract: The threat to the aquatic environment posed by root zone leaching of estrogens from manure-treated fields has hitherto been overlooked. The steroid hormones 17-estradiol (E2) and its degradation product estrone (E1) are of particular environmental concern as both are abundant in slurry from pregnant and cycling pigs and both are potential endocrine disruptors (lowest observable effect level (LOEL) 14 and 3.3 ng/L, respectively). The present one-year study examines the transport of E1 and E2 from manure to tile drainage systems at two field sites on structured, loamy soil. The estrogens leached from the root zone to tile drainage water in concentrations exceeding the LOEL for as long as 3 months after application, with the maximum recorded concentration of E1 and E2 being 68.1 and 2.5 ng/L, respectively. Transport of estrogens from the soil to the aquatic environment was governed by pronounced macropore flow and consequent rapid movement of the estrogens to the tile drains. These findings suggest that the application of manure to structured soils poses a potential contamination risk to the aquatic environment with estrogen, particularly when manure is applied to areas where the majority of streamwater derives from drainage water. -------------------------------------------------------------------------------- Mass Balance of Metolachlor in a Grassed Phytoremediation System Keri L. Henderson, Jason B. Belden, and Joel R. Coats* Department of Entomology, Iowa State University, Ames, Iowa 50011, and Department of Environmental Studies, Baylor University, Waco, Texas 76798 Received for review July 14, 2006 Revised manuscript received January 31, 2007 Accepted February 26, 2007 Abstract: Metolachlor is a point-source pollutant at agrochemical dealerships in the Midwest, as well as a non point-source contaminant of surface waters caused by runoff. Prairie grasses have been used in filter strips to control runoff and are also useful for phytoremediation; however, little is known about the fate of metolachlor and its metabolites within a grassed system. Effects of uptake by prairie grasses on the formation and fate of degradation products are not known. In this study, [U-ring-14C]metolachlor was added to enclosed systems to determine the fate of the parent compound and its metabolites in soil and plants. Mineralization and volatilization were monitored over the 97 day study and found to be 1.05 and 0.2%, respectively, for vegetated systems. At the end of the study, soil and plant material was evaluated for the presence of parent metolachlor and selected metabolites, as well as bound residues. Metolachlor ethane sulfonic acid was the dominant metabolite in soil and plant tissue. Over 7% of applied radioactivity was taken up by the grasses, and plant uptake/metabolism appeared to be the main mechanism for phytoremediation of metolachlor. Vegetation significantly reduced the amount of metolachlor in soil by 9%, indicating potential success as a remediation tool. -------------------------------------------------------------------------------- |
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