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Occurrence of glyphosate and acidic herbicides in select urban rivers and streams in Canada, 2007 总被引:2,自引:1,他引:1
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Comparison of metastable atom bombardment and electron capture negative ionization for the analysis of polychloroalkanes 总被引:3,自引:0,他引:3
A new method for quantifying C10-C13 polychloroalkanes (PCAs or chloroparaffins, CPs) in environmental samples using metastable atom bombardment ionization (MAB) and high resolution mass spectrometry is presented. Contrary to electron capture negative ionization (ECNI), MAB can produce spectra for molecules having a low number of chlorine atoms. These molecules are present in commercial PCAs and are responsible for a large fraction of the total PCA concentration in water samples analysed. Using ECNI or MAB, no molecular ion can be seen in the spectra. ECNI spectra contain important peaks corresponding to [M-Cl]- and [M-HCl]-* while the base peak in MAB spectra is [M-Cl]+ with no [M-HCl]+* present. The mass range for C10-C13 CPs is very large and scanning the masses for all the compounds involved would lead to a loss of sensitivity. Two chromatographic analysis are thus performed using high resolution selective ion monitoring with only a limited number of masses recorded per run. To reduce analysis time, a short capillary column is used. Application of this method to the analysis of high-volumes water samples (dissolved and particulates portions separately) from the St. Lawrence river near Quebec City using MAB is presented. Contribution of molecules with a low chlorine content in the samples account for between 10% and 46% to the total concentration. Congeners distribution between the different fractions indicates that molecules with a low number of carbon atoms are preferentially retained on the particulates. Within a carbon number group, there is a slight tendency to accumulate molecules with a high number of chlorine atoms in the dissolved fraction. 相似文献
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Decker Karin L. Fink Michelle M. Rondeau Renée J. 《Regional Environmental Change》2017,17(8):2467-2475
Regional Environmental Change - Climate change vulnerability assessment is a key first step for land managers attempting to address the potential impacts of future climatic conditions on important... 相似文献
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Compensation for wildlife damages: Habitat conversion, species preservation and local welfare 总被引:1,自引:0,他引:1
We develop a model of hunting, farming and defensive action to study the environmental and economic consequences of introducing a program to compensate peasants of a small economy for the damage caused by wildlife. We show that the widespread belief that compensation induces wildlife conservation may be erroneous. Compensation can lower the wildlife stock, and may result in a net welfare loss for local people. 相似文献
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Seasonal variability of mercury content of Mytilus edulis (L.) was studied at monthly intervals for 18 mo (June 1978–December 1979) in a natural population from a typical estuarine environment (St. Lawrence Estuary). Body-size-induced variability was observed in the same population in spring 1980. The regression coefficients of log-log relationships between mercury content and body size of the mussels varied with time. However, the regression coefficients were never higher than 1; this indicates, therefore, no net accumulation of mercury with age of the bivalve. A normalization method, taking into account shell length and soft-tissue dry weight, is proposed to minimize the metal variations due to size differences of the mussels. The normalized mercury contents vary seasonally by a factor of two. Minimum values were observed during summer. This factor (2) is taken as the minimal difference which can be accepted as indicating a significant geographical trend in a mussel watch-type study in estuarine environments. In the St. Lawrence Estuary and Gulf, size-normalized concentrations range from 69 to 378 ng Hg g-1 (dry weight); highest levels were observed in areas where freshwater influence is maximum, while lower contents were encountered in regions of highest Atlantic influence. In the Gulf, mercury in mussel soft tissue is 3x104 times that of the seawater. There is some indication of a decrease in the previous measured levels near the mouth of the Saguenay fjord in the Lower St. Lawrence estuary. 相似文献
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McCune Frédéric Samson-Robert Olivier Rondeau Sabrina Chagnon Madeleine Fournier Valérie 《Environmental science and pollution research international》2021,28(14):17573-17586
Environmental Science and Pollution Research - Water is essential for honey bees (Apis mellifera L.), but contaminated sources of water in agricultural environments represent a risk of exposure to... 相似文献
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