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Kimiran-Erdem A Arslan EO Sanli Yurudu NO Zeybek Z Dogruoz N Cotuk A 《Environmental monitoring and assessment》2007,125(1-3):219-228
A hundred Enterococcus strains were isolated from seawater samples collected from coastal areas of Istanbul. Isolates were identified to the species
level using standard biochemical tests specified by Facklam and Collins. The species distribution was as follows Enterococcus
faecalis (96%), Enterococcus gallinarum (3%) and Enterococcus solitarius (1%). The resistance of bacteria to both heavy metals (zinc [Zn], iron [Fe], cadmium [Cd], chrome [Cr], cobalt [Co]) and
antibiotics (ampicillin 10 μg [AP], penicillin G 10 Units [PG], gentamycin 10 μg [GM], streptomycin 10 μg [S], chloramphenicol
10 μg [C], erythromycin 15 μg [E], kanamycin 30 μg [K], amikacin 30 μg [AK], nalidixic acid 30 μg [NA], and vancomycin 30 μg
[VA]) was evaluated. None of the strains was resistant to VA. It was found that among the 100 isolates, those that exhibit
resistance to antibiotics, particularly NA, S and K, were also resistant all the heavy metals tested. To our knowledge this
is the first report focusing on determination of resistance of environmental enterococci found in Istanbul against heavy metals
and antibiotics. Thus, combined expressions of antibiotic and heavy metal resistance may help to reinforce ecological and
epidemiological studies and to determine the role of these strains in antibiotic and heavy metal resistance dissemination. 相似文献
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三峡库区柑橘对土壤重金属吸收富集特征研究 总被引:8,自引:0,他引:8
研究区域柑橘果实重金属含量符合NY/T 426-2000<绿色食品柑橘>标准,果实品质达到一级产品.土壤中重金属的含量越高,柑橘叶片、果皮、果肉的重金属含量也越高.柑橘叶片对土壤重金属铜、锌、铅、镉、镍、汞、砷、铬的吸收富集能力显著大于果皮与果肉,果皮对土壤重金属铜、锌、铅、镉、汞的吸收富集能力显著大于果肉,果肉对土壤重金属铬的吸收富集能力显著大于果皮.柑橘同一部位对土壤中不同重金属元素的吸收富集能力也存在很大的差异,柑橘叶片对土壤中不同重金属元素的富集系数大小顺序为Hg>Pb>Cd>Cu>Zn>Cr>As>Ni,柑橘果皮对土壤中不同重金属元素的富集系数大小顺序为Cd>Hg>Cu>Zn>Pb>Cr>Ni>As,柑橘果肉对土壤中不同重金属元素的富集系数大小顺序为Hg>Cu>Cr>Zn>Cd>Ni>Pb>As. 相似文献
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Natural pumice particles were used as granular support media and coated with iron oxides to investigate their adsorptive natural organic matter (NOM) removal from waters. The impacts of natural pumice source, particle size fraction, pumice dose, pumice surface chemistry and specific surface area, and NOM source on the ultimate extent and rate of NOM removal were studied. All adsorption isotherm experiments were conducted employing the variable-dose completely mixed batch reactor bottle-point method. Iron oxide coating overwhelmed the surface electrical properties of the underlying pumice particles. Surface areas as high as 20.6m(2)g(-1) were achieved after iron coating of pumice samples, which are above than those of iron coated sand samples reported in the literature. For all particle size fractions, iron coating of natural pumices significantly increased their NOM uptakes both on an adsorbent mass- and surface area-basis. The smallest size fractions (<63 microm) of coated pumices generally exhibited the highest NOM uptakes. A strong linear correlation between the iron contents of coated pumices and their Freundlich affinity parameters (K(F)) indicated that the enhanced NOM uptake is due to iron oxides bound on pumice surfaces. Iron oxide coated pumice surfaces preferentially removed high UV-absorbing fractions of NOM, with UV absorbance reductions up to 90%. Control experiments indicated that iron oxide species bound on pumice surfaces are stable, and potential iron release to the solution is not a concern at pH values of typical natural waters. Based on high NOM adsorption capacities, iron oxide coated pumice may be a promising novel adsorbent in removing NOM from waters. Furthermore, due to preferential removal of high UV-absorbing NOM fractions, iron oxide coated pumice may also be effective in controlling the formation of disinfection by-products in drinking water treatment. 相似文献
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The paper describes an experimental set-up designed to measure the volatilization of different pesticides after application under full-scale field conditions. The pesticides were sprayed around the circumference of a circle and measurements of meteorology and air concentrations of pesticides were taken in the centre of the circle. The paper describes how the dimensions like the radius of the circle and height of the mast in the experimental set-up are found from theoretical considerations. A method to increase the confidence of the flux calculations is described. It utilizes that several substances were applied simultaneously and that a certain parameter in the fitted concentration profiles depends on turbulence only and thus have the same value for all substances. The design was used during two campaigns, conducted on the same location, one during fall on bare soil and one in spring on a barley crop. 相似文献
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三峡库区面源污染现状与对策研究 总被引:34,自引:4,他引:34
三峡库区生态环境脆弱,坡耕地垂直分布明显,耕地利用方式不合理,库区耕地环境质量较差。水土流失严重。库区沿江工厂星落棋布,落后的生产工艺和小规模生产,使大量废水没经处理直接排放到库区各大河流。虽然目前长江流域水体的自净作用能将污水稀释,但随着三峡大坝的正式蓄水,部分区域水体污染将不可避免。通过对库区部分区域水体近几年的连续监测,水体总P、非离子氨、CODcr等指标有恶化趋势。库区土壤重金属监测结果表明,土壤重金属Cd、As含量明显增加,并且远大于当地土壤背景值。库区农畜产品蔬菜、茶叶、鱼Pb、Cd超标较严重。土壤N、P流失率较高。有效防止库区面源污染的对策一方面是控制工业点源、线源污染造成的面源污染.另一方面是控制农业自身造成的面源污染。主要措施有:加强库区环境管理和环保宣传力度;建立沿江生物隔离带;加强土地管理,加大农业工程投入,合理利用土地;大力提倡水土保持耕作法;扩大森林覆盖率,建立坡地立体复合农业生态系统:建立面源污染预警系统。 相似文献
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Phosphorus adsorption and desorption potential of stream sediments and field soils in agricultural watersheds 总被引:1,自引:0,他引:1
Agudelo SC Nelson NO Barnes PL Keane TD Pierzynski GM 《Journal of environmental quality》2011,40(1):144-152
Phosphorus release from stream sediments into water could increase P loads leaving agricultural watersheds and contribute to lag-time between implementation of best management practices and improvement in water quality. Improved understanding of P release from stream sediments can assist in setting water quality goals and designing stream monitoring programs. The objective of this study was to estimate the relative potential of sediments and soils to release P to stream water in two agricultural watersheds. Stream sediments were collected from banks, pools, riffles, and depositional features. Soils were sampled from wheat, row crop, pasture, and manure-amended fields. Sediments and soils were analyzed for equilibrium P concentration at zero net P sorption (EPC0), maximum P adsorption capacity (P(max)), anion exchange extractable P (P(lab)), and degree of P saturation. Dissolved reactive P (DRP) of stream water was monitored. Stream sediment EPC0 was similar to or less than EPC0 from field soils; however, P(lab) of stream sediments was three times less than field soils. Sediments were sandy and had low P(max) due to low oxalate-extractable Fe and Al, which could be explained by stream geomorphology. Manure-amended fields had the highest EPC0 and P(lab) due to continued inputs of manure-based P; however, conventionally fertilized fields also represented an important P source due to their vast extent. Stream water DRP was similar to EPC0 of sediments during base flow and similar to EPC0 of field soils during storm flow. These results indicate that sediments in these streams are a relatively minor P source. 相似文献
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