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681.
682.
683.
有机磷农药生产废水处理技术研究 总被引:1,自引:0,他引:1
对含环链结构的甲基异柳磷等有机磷农药生产废水的处理技术进行了试验研究.结果表明,采用湿式氧化法,若工作压力为0.5~0.6MPa(150一160℃),pH值为2,停留时间1h,COD_(cr)和有机磷去除率分别为59.8%和91.3%,BOD_5/COD_(cr)由0.12提高到0.46.采用活性污泥法与生物活性炭法,若混合废水稀释后直接处理,在选定的条件下,COD_(cr)去除率分别为76.0%和82.1%;经湿式氧化后稀释再进行生物处理,COD_(cr)去除率可增加约10%. 相似文献
684.
聚乙烯醇包埋活性炭与微生物的固定化技术及其对水胺硫磷降解的研究 总被引:42,自引:1,他引:41
提出聚乙醇包埋活性炭与微生物的固定化技术,给出较好的制备工艺,并对有机磷农药水胺硫磷的降解进行了试验研究,结果表明,经固定的微生物对温度、pH值和水样水胺硫磷浓度的适应范围扩大,在3个月连续试验中,若水样初始CODcr浓度为1300-2500mg/L,停留时间24h,在恒温摇床内降解,其去除率为55%-72%。 相似文献
685.
Determination and Assessment of HCHs and DDTs Residues in Sediments from Lake Dongting, China 总被引:5,自引:0,他引:5
The contamination of organochlorine pesticides hexachlorocyclohexane (HCH) and Dichlorodiphenyltrichloroethane (DDT) and their
eco-environmental assessment in surface sediments from Lake Dongting, the second-largest freshwater lake in China, were studied.
Concentrations of ∑HCH (=α-HCH + β-HCH + γ-HCH +δ-HCH) were 0.21--9.59 ng/g dry weight and those of ∑ DDT = p,p'-DDD+p,p'-DDE+o,p'-DDT+p,p'-DDT)
ranged from under detectable limit to 10.15 ng/g dry weight. The ratios of α-HCH to γ-HCH were above 7 at most sampling sites
while no or a small amount of β-HCH were found at all sites, suggesting the degradation of HCH used in the history and possibly
current use of HCH in the region. The low ratios (below 2.0 in most cases) of (p,p'-DDE+p,p'-DDD) to p,p'-DDT and high levels
of individual isomers of DDT at some sites also suggested that there have still been fresh inputs of DDT into Lake Dongting.
Through the comparison between concentrations of HCH and DDT residues in sediments of Lake Dongting and those from other places
in China and also from the results of our eco-environmental assessment, it can be concluded that Lake Dongting is the water
body with high contamination of both HCH and DDT in its sediments in comparison with other water bodies in China. 相似文献
686.
Lake Vela, located in the Portuguese littoral-centre, is a temperate shallow lake exhibiting a high trophic status. This aquatic
ecosystem has been potentially exposed to contamination generated by agricultural and livestock activities held in their drainage
basin, which seriously compromise their health. This work summarizes some background information and presents the problem
formulation step of the ERA. Therefore, it evaluates the characteristics of the stressor(s), describes the ecological system
and receptors and suggests a conceptual model, which predicts the potential exposure pathways, relating suspected sources
to the defined endpoints. This introductory step also described an analysis plan on the entire study, which includes a delineation
of the assessment design, data needs, measures, and methods for conducting the analysis phase of the risk assessment process. 相似文献
687.
688.
Kocí V Ocelka T Dragoun D Vit M Grabic R Sváb M 《Environmental science and pollution research international》2007,14(2):94-101
Background, Aim and Scope
The article is focused on dioxin, furan, PCB and organochlorine pesticide monitoring in the surface waters of the Central
European, protected natural reserve Krivoklatsko, under the UNESCO programme Man and Biosphere. Persistent compounds are presently
transported via different means throughout the entire world. This contamination varies significantly between sites. This raises
the question of what constitutes the naturally occurring background levels of POPs in natural, unpolluted areas, but which
are close to industrialised regions. Information of real background POP contamination can be of high value for risk assessment
management of those sites evidently polluted and for the defining of de-contamination limits.
Preserved areas should not be seen as isolated regions in which the impacts of human activities and natural factors are either
unexpected or overlooked. Every ambient region, even those protected by a law or other means, are still closely connected
to neighbouring human developed and impacted areas, and are therefore subject to this anthropogenic contamination. These areas
adjacent to natural reserves are sources of diverse substances, via entry of air, water, soil and/or biota. After an extended
period of industrial activities, organochlorine pollutants, even those emitted in trace concentrations have reached detectable
levels. For future research and for the assessment of environmental changes, present levels of contamination would be of high
importance. This work publishes data of the contamination with organochlorine pollutants of this natural region, where biodiversity
and ecological functions are of the highest order.
Materials and Methods:
Semipermeable membrane devices (SPMDs) were utilised as the sampling system. SPMDs were deployed in two small creeks and one
water reservoir selected in the central part of the Krivoklatsko Natural Reserve, where it could be expected that any possible
contamination by POPs would be lowest. The exposed SPMDs were analysed both for chemical contents of POPs and for toxicity
properties. The chemical analyses of dibenzo-dioxins, dibenzo-furans, PCBs and OCPs were analysed by GC/MS/MS on GCQ or PolarisQ
(Thermoquest). Toxicity bioassays were performed on the alga Desmodesmus subspicatus, bacteria Vibrio fischeri and crustacean
Daphnia magna. All toxicity data were expressed as the effective volume Vtox. Vtox is a toxicity parameter, the determination
of which is independent of SPMD deployment time and pre-treatment dilution (unlike, for example, the EC50 of the SPMD extract).
Results:
The following chemical parameters were monitored: 1) tetra, penta, hexa and hepta dibenzo-p-dioxins and furans; 2) all those
detectable from tri- through deca-polychloriated biphenyls (PCBs) and 3) a group of organochlorine pesticides: hexachlorobenzene
and isomers of hexachlorocyclohexane, DDE, DDD and DDT. The concentrations of dioxins and furans on the assessed sites varied
from under detection levels up to 7 pg.l-1; PCBs were detected in a sum concentration up to 2.8 ng.l-1; and organochlorine
pesticides up to 346 pg.l-1. The responses of bioassays used were very low, with the values obtained for Vtox being under
0.03 l/d.
Discussion:
Toxicity testing showed no toxicity responses, demonstrating that the system used is in coherence with the ecological status
of the assessed sites. Values of Vtox were under the critical value – showing no toxicity. The PCA of chemical analysis data
and toxicity responses resulted in no correlations between these two groups of parameters. This demonstrated that the present
level of contamination has had no direct adverse effects on the biota.
Conclusions:
The concentration values of six EPA-listed, toxic dioxins and sums of tetra-hepta dioxins; nine EPA toxic dibenzofurans and
the sums of tetra-hepta bibenzofurans are presented together with all tri-deka PCBs and organochlorine pesticides (alfa-,
beta-, gama-, delta-HCH, HCB, opDDE, ppDDE, opDDD, ppDDD, opDDT, ppDDT). These values represent possible current regional
natural background values of these substances monitored within the Central European region, with no recorded adverse effects
on the freshwater ecosystem (up until the present time).
Recommendations and Perspectives:
Assessment of dioxins, furans and other organochlorine compounds within natural reserves can be important for the monitoring
of human-induced impacts on preserved areas. No systematic monitoring of these substances in areas not directly affected by
industry has generally been realised. There is a paucity of data of the presence of any of these substances within natural
regions. Further monitoring of contamination of both soil and biota by dioxins and furans in preserve regions is needed and
can be used for future monitoring of man-made activities and/or accidents.
Semipermeable membrane devices proved to be a very good sampling system for the monitoring of trace concentrations of ambient
organochlorine compounds. Toxicity evaluation using the Vtox concept demonstrated that those localities assessed expressed
no toxicity. 相似文献
689.
Persistent Organochlorine Pesticide Residues in Soil and Surface Water of Northern Indo-Gangetic Alluvial Plains 总被引:1,自引:0,他引:1
This study reports the concentration levels and distribution pattern of the organochlorine pesticide (OCPs) residues in the
soil and surface water samples collected from the northern Indo-Gangetic alluvial plains. A total of 31 soil and 23 surface
water samples were collected from the study region in Unnao district covering an area of 2150 km2 and analyzed for aldrin, dieldrin, endrin, HCB, HCH isomers, DDT isomers/metabolites, endosulfan isomers (α and β), endosulfan
sulfate, heptachlor and its metabolites, α-chlordane, γ-chlordane and methoxychlor. In both the soil and surface water samples
β- and δ-isomers of HCH were detected most frequently, whereas, methoxychlor was the least detected pesticide. The results
showed contamination of soil and surface water of the region with several persistent organic pesticides. The total OCPs level
ranged from 0.36–104.50 ng g–1 and 2.63–3.72 μg L–1 in soil and surface water samples, respectively. 相似文献
690.
The objective of this study was to conduct a comprehensive comparison of the effect on acetylcholinesterase (AChE) from various tissues of Mytilus trossulus caused by in vitro exposure to several pesticides and metals, because results available in the literature are inconsistent, difficult to compare, and sometimes contradict each other. For this purpose, fraction S10 extracted from gills, digestive gland, mantle and muscles, and the whole soft tissue of the mussel was exposed to several pesticides (dichlorvos, chlorpyrifos, fenitrothion, carbofuran and carbaryl) and metals (Cu, Zn, Cd, Hg, Pb) at a wide range of concentrations. AChE was inhibited in 50% or more in all the tissues exposed to dichlorvos, Cu, Hg and the mixture of Cu+Cd, and in some tissues exposed to carbaryl and carbofuran. The IC50 was calculated where possible. No inhibition was found in the case of chlorpyrifos, Cd, Pb, and Zn. 相似文献