The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform
T. Laier - One of the best experts on this subject based on the ideXlab platform.
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Spatial variation in natural formation of Chloroform in the soils of four coniferous forests
Biogeochemistry, 2011Co-Authors: C. N. Albers, O. S. Jacobsen, É. M. M. Flores, J. S. F. Pereira, T. LaierAbstract:Natural Chloroform in soil gas below four coniferous forest sites was studied. High concentrations were found within narrow areas—Hot Spots—varying from ~25 to >400 m^2 in size, with Chloroform concentrations being typically 20–100 times those in corresponding Low Spots.Attempts to localize Hot Spots by visual inspection with regard to type and density of vegetation failed. Possible differences between Hot and Low Spots could be emission, leaching or degradation of Chloroform. However, emissions of Chloroform from Hot Spots were ~10 times higher than from Low Spots and similarly the Chloroform concentration in groundwater below a Hot Spot was ~10 times higher than below the corresponding Low Spot. No differences in Chloroform mineralization rates were observed between sites and incubation of soil cores confirmed a larger net formation of Chloroform in the Hot Spots. Various soil parameters were measured in order to compare the soil sampled from Hot and Low Spots. The halogenation degree of organic soil samples was in the same range, although slightly higher in the H-horizon of the Hot Spot. The Chloroform formation potential of the soil organic matter showed differences between soil horizons but not between sites. The high levels of Chloroform in the Hot Spots are probably best explained by differences in Chloroform forming activity caused by an uneven distribution of yet unidentified microorganisms, since differences in soil organic matter quality and in emission, leaching and degradation of Chloroform as well as a number of additional soil parameters could be completely ruled out.
Molly Lutcavage - One of the best experts on this subject based on the ideXlab platform.
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a comparison of carbon and nitrogen stable isotope ratios of fish tissues following lipid extractions with non polar and traditional Chloroform methanol solvent systems
Rapid Communications in Mass Spectrometry, 2008Co-Authors: John M Logan, Molly LutcavageAbstract:Stable isotope ratios act as chemical tracers of animal diet, and are used to study food web dynamics. Because carbon stable isotope values are influenced by tissue lipid content, a number of extraction methods have been used to remove lipid bias, but, in some species and tissues, extractions also alter nitrogen isotope values. We have analyzed delta(13)C and delta(15)N in Atlantic bluefin tuna liver and white muscle, and whole Atlantic herring, fish tissues covering a wide range of lipid content (bulk C:N 3.1-12.5). In order to compare delta(13)C and delta(15)N values from traditional Chloroform/methanol extractions with non-polar solvent alternatives, we analyzed samples following (1) no treatment, (2) lipid removal using Chloroform/methanol (2:1), and (3) Soxhlet extractions using Chloroform, diethyl ether or hexane. Chloroform/methanol and Chloroform extractions produced the lowest C:N values and highest delta(13)C values. In bluefin tuna, Chloroform and hexane extractions significantly altered liver delta(15)N, and all methods significantly altered delta(15)N values in white muscle. Whole Atlantic herring delta(15)N was not altered by any extraction method, while the 2:1 Chloroform/methanol extraction most completely removed fish tissue lipid components. Our results indicate that delta(15)N effects are not limited to common Chloroform/methanol extractions and suggest that Chloroform/methanol is the most effective extraction for delta(13)C correction. Given evidence for delta(15)N alteration among all tested methods, mathematical correction approaches should be further explored as an alternative to lipid correction.
Nativ Rotbart - One of the best experts on this subject based on the ideXlab platform.
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examination of residual Chloroform interference in the measurement of microbial biomass c by fumigation extraction
Soil Biology & Biochemistry, 2017Co-Authors: Nativ Rotbart, Mikhail Borisover, Nadezhda Bukhanovsky, Alla Nasonova, Asher Bartal, Adi OrenAbstract:Abstract Using the Chloroform fumigation-extraction (CFE) method for determining microbial biomass in soils, a presumption is followed, i.e., that Chloroform becomes fully evacuated from the fumigated soil before extraction. Otherwise, the C-containing fumigant may comprise an unknown part of the extractable C flush, resulting in certain overestimation of soil microbial biomass. A quantitative assessment of extractable residual Chloroform levels in fumigated soils was performed, testing soils varying in clay and organic matter contents. The tests were performed over a broad range of soil moisture conditions as to facilitate a mechanistic interpretation of possible Chloroform interactions in the studied soils (i.e., dissolution, sorption). The results support the validity of the CFE method's application in agricultural soils, demonstrating the insignificance of biomass overestimation arising from residual Chloroform.
C. N. Albers - One of the best experts on this subject based on the ideXlab platform.
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Spatial variation in natural formation of Chloroform in the soils of four coniferous forests
Biogeochemistry, 2011Co-Authors: C. N. Albers, O. S. Jacobsen, É. M. M. Flores, J. S. F. Pereira, T. LaierAbstract:Natural Chloroform in soil gas below four coniferous forest sites was studied. High concentrations were found within narrow areas—Hot Spots—varying from ~25 to >400 m^2 in size, with Chloroform concentrations being typically 20–100 times those in corresponding Low Spots.Attempts to localize Hot Spots by visual inspection with regard to type and density of vegetation failed. Possible differences between Hot and Low Spots could be emission, leaching or degradation of Chloroform. However, emissions of Chloroform from Hot Spots were ~10 times higher than from Low Spots and similarly the Chloroform concentration in groundwater below a Hot Spot was ~10 times higher than below the corresponding Low Spot. No differences in Chloroform mineralization rates were observed between sites and incubation of soil cores confirmed a larger net formation of Chloroform in the Hot Spots. Various soil parameters were measured in order to compare the soil sampled from Hot and Low Spots. The halogenation degree of organic soil samples was in the same range, although slightly higher in the H-horizon of the Hot Spot. The Chloroform formation potential of the soil organic matter showed differences between soil horizons but not between sites. The high levels of Chloroform in the Hot Spots are probably best explained by differences in Chloroform forming activity caused by an uneven distribution of yet unidentified microorganisms, since differences in soil organic matter quality and in emission, leaching and degradation of Chloroform as well as a number of additional soil parameters could be completely ruled out.
Gunilla Öberg - One of the best experts on this subject based on the ideXlab platform.
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Chloroform in runoff water—a two-year study in a small catchment in Southeast Sweden
Biogeochemistry, 2007Co-Authors: Teresia Svensson, Per Sandén, Frank Laturnus, Gunilla ÖbergAbstract:Chloroform concentrations were observed and input and output fluxes estimated over a 2-yr period in a small coniferous catchment (0.22 km^2) in southeast Sweden. Water discharge was measured daily, and runoff water was sampled bi-weekly for Chloroform analysis. An approximate Chloroform budget was calculated, which indicated that the annual output of 6 μg m^−2 yr^−1 was approximately six times higher than the input, inferring an internal source of Chloroform in the catchment. To the best of our knowledge, neither flux estimates nor mass balances have previously been made for Chloroform on a catchment scale, nor have data regarding natural runoff variation with time been gathered. Concentrations of Chloroform in runoff were found to be generally high during wet periods, such as spring, but also peaked during summer rain events. The observed pattern suggests that Chloroform is formed in surface soil layers and transported to the outlet under high-flow conditions and during dry-period rain events; it is lost through degradation or evaporation during drier periods due to longer soil water residence times. The data suggest that the variation among replicates increases with concentration; this emphasizes the need to know what the degree of on-site variation is, so one can collect a sufficient number of replicates to permit detection of spatial or temporal changes.