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Volatilization Loss (volatilization + loss)
Selected AbstractsEvaluation of the environmental fate of thymol and phenethyl propionate in the laboratoryPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 7 2008Dingfei Hu Abstract BACKGROUND: The natural monoterpenoid pesticides thymol and phenethyl propionate (PEP) are used indoors and outdoors, but their fate in the environment has not been reported. In order better to understand their impact on the environment, water metabolism and soil metabolism studies were conducted with thymol and PEP at a concentration of 10 µg g,1 in water and in soil under laboratory conditions. RESULTS: Dissipation half-lives of thymol and PEP were 16 and 5 days in water and 5 and 4 days in soil. 2-Phenylethanol and 2-(4-hydroxyphenyl)ethanol were detected as primary degradation products of PEP. Over time, a considerable volatilization loss of thymol, but not of phenethyl propionate, was found in the 1 month study under the experimental conditions used. Less than 6% of thymol and PEP were detected as bound residues, and less than 3% were mineralized during the 30 day study. CONCLUSION: In order to maximize the pesticidal effect, more attention should be paid to the temperature for thymol than for PEP when they are being applied, owing to the high volatility of the former. Thymol and PEP pose low risks to the ecosystem because of their rapid dissipation and low bound residues in the environment. Copyright © 2008 Society of Chemical Industry [source] Environmental fate of metalaxyl and chlorothalonil applied to a bentgrass putting green under southern California climatic conditionsPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 4 2002L Wu Abstract Putting greens usually receive high inputs of fertilizers and pesticides to meet the high demand for visual quality and to overcome the stress from close mowing and traffic. In this study, two commonly used fungicides, metalaxyl (methyl N -(methoxyacetyl)- N -(2,6-xylyl)- DL -alaninate) and chlorothalonil (2,4,5,6-tetrachloro-1,3-benzenedicarbonitrile), were evaluated for their partitioning and persistence in a bentgrass (Agrostis palustris Huds) putting green under southern California climatic conditions. The putting green site was constructed according to the US Golf Association (USGA) specifications. Lysimeter assemblies installed at the center of each plot were used to monitor the leachate, flux chambers were used to measure volatilization, clippings were collected to determine the residues on grass, and soil cores were sampled to determine residues in the soil profile. Results showed that cumulative volatilization loss accounted for 0.10 and 0.02%, clipping removal 0.11 and 0.13%, and cumulative leaching 0.71 and 0.002% of the applied metalaxyl and chlorothalonil, respectively. The two fungicides were mainly found in the top 10,cm of the soil profile due to the high organic carbon content in the thatch and mat layers. The dissipation half-life was 1.4 days for metalaxyl and 4.9 days for chlorothalonil on grass, shorter than those found in agricultural fields. This study showed that, under normal turf management practices, the offsite transport of the parent fungicides was minimal. Future research should focus on investigating the fate and mobility of the metabolites of the fungicides. © 2002 Society of Chemical Industry [source] Aerobic biological treatment of waste- waters containing dichloromethaneJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2007Sandra C Moura Abstract BACKGROUND: Volatilization has been advanced as one of the predominant phenomena contributing to volatile organic carbon emissions from wastewater treatment plants (WWTPs). In this study, strategies for minimizing such air stripping losses when treating a liquid stream containing dichloromethane (DCM), aiming at decreasing the overall emission inventory from WWTPs, were investigated. RESULTS: System R1, consisting of a continuous flow stirred tank reactor (CSTR) treating a liquid stream containing DCM at a concentration of 12 mmol dm,3 presented a biodegradation efficiency (BE) of 68%, based upon chloride release, with 10% of measurable losses, mainly due to volatilization, and 22% of unmeasurable losses. System R2 introduced operational designs aiming at decreasing DCM volatilization. In Experiment R2.1, a biotrickling filter, through which the air stripped from the CSTR was driven, was introduced leading to a reduction from 10% to 7% on the measurable losses. In Experiment R2.2, the air stripped from the CSTR was recirculated at a flow rate of 2.4 dm3 h,1 through the reactor medium before entering the biotrickling filter. The BE was improved from 69% to 82% and the losses associated with air stripping were successfully reduced to 2%. The proposed design, including air recirculation and the biotrickling filter, increased the ratio between the biodegradation rate and the volatilization rate from 7 to 41. CONCLUSIONS: Recirculation of the gaseous effluent through the reactor medium, which allowed for higher residence time within the bioreactor, was shown to be a successful strategy for improving the treatment process, thus minimizing DCM volatilization losses. Copyright © 2007 Society of Chemical Industry [source] Presubmergence and green manure affect the transformations of nitrogen-15-labeled urea under lowland soil conditionsJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 4 2003H.S. Thind Abstract The effect of presubmergence and green manuring on various processes involved in [15N]-urea transformations were studied in a growth chamber after [15N]-urea application to floodwater. Presubmergence for 14 days increased urea hydrolysis rates and floodwater pH, resulting in higher NH3 volatilization as compared to without presubmergence. Presubmergence also increased nitrification and subsequent denitrification but lower N assimilation by floodwater algae caused higher gaseous losses. Addition of green manure maintained higher NH4+ -N concentration in floodwater mainly because of lower nitrification rates but resulted in highest NH3 volatilization losses. Although green manure did not affect the KCl extractable NH4+ -N from applied fertilizer, it maintained higher NH4+ -N content due to its decomposition and increased mineralization of organic N. After 32 days about 36.9,% (T1), 23.9,% (T2), and 36.4,% (T3) of the applied urea N was incorporated in the pool of soil organic N in treatments. It was evident that the presubmergence has effected the recovery of applied urea N. No translation. [source] | ||||||||||