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SOON-WOONG CHANG SI-JIN LEE CHUNG-HWAN JE 《Journal of environmental science and health. Part. B》2013,48(6):801-811
Toxicity, uptake, and transformation of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] by three species of poplar tree were assessed. Poplar cuttings were grown in sealed flasks with hydrophonic solutions and exposed to various concentrations of atrazine for a period of two weeks. Toxicity effects were evaluated by monitoring transpiration and measuring poplar cutting mass. Exposure to higher atrazine concentrations resulted in decrease of biomass and transpiration accompanied by leaf chlorosis and abscission. However, poplar cuttings exposed to lower concentrations of atrazine grew well and transpired at a constant rate during experiment periods. Poplar cuttings could take up, hydrolyze, and dealkylate atrazine to less toxic metabolites. Metabolism of atrazine occurred in roots, stems, and leaves and became more complete with increased residence time in tissue. These results suggest that phytoremediation is a viable approach to removing atrazine from contaminated water and should be considered for other contaminants. 相似文献
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Maosheng Yao John McFadden 《Journal of the Air & Waste Management Association (1995)》2013,63(8):1245-1253
Abstract Air quality is degraded by many factors, among which the emissions from on‐road vehicles play a significant role. Timely and accurate estimate of such emissions becomes very important for policy‐making and effective control measures. However, lack of traffic data and outdated emission software make this task difficult. This research has demonstrated a new method that facilitates the vehicular emission inventories at the local level by using shorter-time Highway Performance Monitoring System (HPMS) traffic data along with the latest U.S. Environment Protection Agency (EPA) emission modeling software, MOBILE6. The conversion methodology was developed for converting readily available HPMS traffic volume data into EPA MOBILE-based traffic classifications, and a corresponding software program was written for automating the process. EPA MOBILE6 model was used to obtain emissions of nitrogen oxides (NOx), volatile organic compound (VOC), and cabon monoxide (CO) emitted by the parent traffic and subsampled traffic data, and these emissions were additionally compared. The case study has shown that the difference of the magnitude between the emission estimates produced by certain subsampled and parent traffic data are minor, indicating that subsampled HPMS data can be used for reporting parent traffic emissions. It was also observed that traffic emissions follow a Weibull distribution, and NOx emissions were more sensitive to the traffic data composition than VOC and CO. Lastly, use of average emission values of 20 or 30 consecutive minutes appears to be valid for representing hourly emissions. 相似文献
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J.?A.?SánchezEmail author C.?S.?McFadden S.?C.?France H.?R.?Lasker 《Marine Biology》2003,142(5):975-987
Octocorals, especially gorgonians, are conspicuous on Caribbean coral reefs, but there is no consensus regarding species relationships. Mitochondrial protein-coding genes [NADH-dehydrogenase subunits 2 (ND2) and 6 (ND6), and mutS homolog (msh1), 1633 bp] from 28 shallow-water species were sequenced to develop the first molecular phylogeny for Caribbean octocorals. The specimens were collected primarily in the Caribbean or off Brazil in 1999-2001. Morphological characters (sclerites and axial ultrastructure) were also examined in order to map them onto the molecular phylogeny. Analyses of both nucleotide and amino acid substitutions using maximum parsimony and likelihood (including maximum-likelihood and Bayesian analysis) generated very similar results, with most nodes having high levels of support. These molecular results were significantly different from the generally accepted classification. Neither Plexauridae nor Gorgoniidae were monophyletic. Plexaurella spp., nominal plexaurids, were basal to the gorgoniids, sharing many morphological characters with them. This corroborates previous findings using secondary metabolites and biosynthetic pathways. The sea fans, Gorgonia spp. and Pacifigorgia spp., as well as the pinnate gorgonians, Muriceopsis flavida and Pseudopterogorgia spp., did not have sea fan or pinnate relatives, suggesting there has been convergent evolution of colony form. Caribbean plexaurids appeared more derived and/or recently evolved according to both morphological and molecular data (e.g. Eunicea spp. and Plexaura spp.). Molecular phylogenetics is a promising approach for reconstructing phylogenetic relationships among octocorals as well as to understand their complex morphology. Electronic Supplementary Material is available if you access this article at http://dx.doi.org/10.1007/s00227-003-1018-7. On that page (frame on the left side), a link takes you directly to the supplementary material. 相似文献