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机油高效降解菌群筛选及降解效果初探 总被引:2,自引:0,他引:2
从多处受石油污染的土壤中经过初步筛选、混合驯化得到以机油为唯一碳源进行生长代谢的混合菌群.利用此混合菌群进行的降解实验结果表明,该菌群对高浓度机油废水具有较强的降解能力,初始含机油约2.0 g/L的人工废水.接种量为0.1%(菌体湿重/培养液体积),经过7 d的降解,机油可降至403 mg/L,降解率达81.4%;对不同浓度机油废水的降解实验结果表明,在静态实验条件下,机油质量浓度在不高于1 000 mg/L(含1 075 mg/L),混合菌群在降解过程中能自行从降解产酸的不良环境中恢复,机油质量浓度在2 000 mg/L以上,初期产酸较多,pH下降幅度较大,在7 d的周期内,废水pH无法恢复,说明在降解后期仍有大量有机酸积累而未被彻底降解;与葡萄糖共基质的降解实验结果表明,经过7 d的降解.不超过150 mg/L,的葡萄糖与1 000 mg/L机油组成的共基质体系中,机油降解基本不受葡萄糖加入的影响,但可加强早期的降解速率.而葡萄糖高于150 mg/L时,则会对混合菌群的除油率产生抑制,抑制程度随着葡萄糖浓度的提高而加大. 相似文献
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九寨沟公路和栈道降雨径流污染负荷过程的研究 总被引:1,自引:0,他引:1
对九寨沟国家公园中的公路和游客栈道进行了人工降雨试验的设计、操作和测试数据分析.模拟试验选择6处公路和栈道试验区,采用人工降雨方法模拟雨量出现概率60%、历时30 min的降雨.试验按3 min间隔对各试验场降雨径流带出的总磷负荷进行现场监测.研究结果提供了在具有代表性的降雨条件对总磷营养物输出的定量估计.尤其对公路和栈道降雨径流特征获得了认识:污染物初始冲刷浓度期延续约3 min;在降雨强度不变的情况下,污染物负荷率接近常量.大部分污染物负荷可由出现频率较大的小降雨事件输出.表明研究结果提供了一种思路,即可采用平均负荷方式取代过去的平均浓度方式去构建公路和栈道的负荷模型. 相似文献
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Occurrence and treatment of arsenic in groundwater and soil in northern Mexico and southwestern USA 总被引:1,自引:0,他引:1
This review focuses on the occurrence and treatment of arsenic (As) in the arid region of northern Mexico (states of Chihuahua and Coahuila) and bordering states of the southwestern US (New Mexico, Arizona, and Texas), an area known for having high As concentrations. Information assembled and assessed includes the content and probable source of As in water, soil, and sediments and treatment methods that have been applied in the area. High As concentrations were found mainly in groundwater, their source being mostly from natural origin related to volcanic processes with significant anthropogenic contributions near mining and smelting of ores containing arsenic. The affinity of As for solid phases in alkaline conditions common to arid areas precludes it from being present in surface waters, accumulating instead in sediments and shifting its threat to its potential remobilization in reservoir sediments and irrigation waterways. Factors such as oxidation and pH that affect the mobility of As in the subsurface environment are mentioned. Independent of socio-demographic variables, nutritional status, and levels of blood lead, cognitive development in children is being affected when exposed to As. Treatments known to effectively reduce As content to safe drinking water levels as well as those that are capable of reducing As content in soils are discussed. Besides conventional methods, emergent technologies, such as phytoremediation, offer a viable solution to As contamination in drinking water. 相似文献
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Blus LJ Henny CJ Hoffman DJ Grove RA 《Environmental pollution (Barking, Essex : 1987)》1995,89(3):311-318
Waterfowl and passerines in northern Idaho in 1987 had high levels of lead in their blood and tissues that originated primarily from mining and smelting activities. Four Canada geese (Branta canadensis) and one common goldeneye (Bucephala clangula) found dead contained 8 to 38 microg/g (wet mass) of lead in their livers. These levels exceed the lower lethal limit of 5 microg/g in experimental birds. Two of the Canada geese (one each from the contaminated and reference areas) died with ingested lead shotgun pellets (shot) in their gizzards, whereas the other three birds from the contaminated area contained no ingested shot and evidently died from ingesting environmental lead in sediment or biota. Lead burdens in most American robins (Turdus migratorius) and mallards (Anas platyrhynchos) were high, whereas those in tree swallows (Tachycineta bicolor) were slightly elevated. Lead accumulated to potentially hazardous levels in blood and tissues of some nestling robins (maxima of 0.87 microg/g in blood and 5.6 microg/g in liver) and mallards (maxima of 10.2 microg/g in blood and 2.8 microg/g in liver). In mallards, lead levels and associated physiological characteristics of blood were significantly different in juveniles (HY) versus adults (AHY). Activity of delta-aminolevulinic acid dehydratase (ALAD) was about 87 to 95% lower than values for control birds in experimental studies. Activity of ALAD was significantly inversely correlated with blood lead levels. Cadmium was detected in kidneys of most birds, but even the maximum concentration of 7.5 microg/g in an AHY mallard was below known harmful levels. 相似文献
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Photodegradation of polychlorinated dibenzo-p-dioxins and dibenzofurans in aqueous solutions and in organic solvents 总被引:7,自引:0,他引:7
Aqueous solutions of selected polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were prepared using a generator column and exposed to UV (300 nm) light in the laboratory and to sunlight in an outdoor environment. In the laboratory, additional exposures were also carried out using 60% acetonitrile/water solutions. At 300 nm di- and tetra PCDDs had higher first-order photodegradation rate constants in 60% acetonitrile/water than in pure water. The solvent effect was reversed for PCDFs. These results may be a reflection of the higher polarity of PCDFs compared to PCDDs. In both the indoor and outdoor exposures photodegradation rates decreased with increasing concentrations of chlorination. However, OCDF exposed to 300 nm light in 60% acetonitrile/water and to sunlight in pure water photodegraded more rapidly than tetra CDF. Photolysis rates in sunlight were considerably slower (t(1/2) of 6.4-23 h) than photolysis rates at 300 nm in the laboratory (t(1/2) of 4.3-680 min), reflecting the lower intensity of sunlight in the 300 nm region of the UV/Vis spectrum. The extent of dechlorination of the PCDDs/PCDFs was less than 20% and reductive dechlorination does not appear to be a major process in the photodegradation of PCDDs/PCDFs in aqueous solutions. 相似文献
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Imidacloprid, the major component of many widely used insecticide formulations, is highly persistent in soils. In this study, the sorption of imidacloprid by six soils as well as its photodegradation and hydrolysis in water were studied. The soils differed significantly in organic matter content and other physical and chemical properties. Sorption increased with increasing soil organic matter content but was not significantly correlated with other soil properties. Removal of organic matter via H2O2 oxidation decreased the sorption. By normalizing the Freundlich coefficients (Kf) to organic matter contents, the variability in obtained sorption coefficient (Kom) was substantially reduced. These results indicate that soil organic matter was the primary sorptive medium for imidacloprid. The low heat of sorption calculated from Kom suggests that partition into soil organic matter was most likely the mechanism. The photodegradation and hydrolysis of imidacloprid in water followed pseudo-first-order kinetics; however, the latter process needed a six-time-higher activation energy. While both processes produced the same main intermediate, they occurred via different pathways. The hydrolysis of imidacloprid was not catalyzed by the high interlayer pH in the presence of metal-saturated clays, which appeared to result from the lack of the pesticide adsorption in the interlayers of clays. 相似文献
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Olli h. Tuovinen Vaidehi Deshmukh Bestamin Özkaya Mark Radosevich 《Journal of environmental science and health. Part. B》2013,48(10):718-726
The purpose of this study was to assess atrazine mineralization in surface and subsurface samples retrieved from vertical cores of agricultural soils from two farm sites in Ohio. The Defiance site (NW-Ohio) was on soybean-corn rotation and Piketon (S-Ohio) was on continuous corn cultivation. Both sites had a history of atrazine application for at least a couple of decades. The clay fraction increased at the Defiance site and the organic matter and total N content decreased with depth at both sites. Mineralization of atrazine was assessed by measurement of 14CO2 during incubation of soil samples with [U-ring-14C]-atrazine. Abiotic mineralization was negligible in all soil samples. Aerobic mineralization rate constants declined and the corresponding half-lives increased with depth at the Defiance site. Anaerobic mineralization (supplemented with nitrate) was mostly below the detection at the Defiance site. In Piketon samples, the kinetic parameters of aerobic and anaerobic biomineralization of atrazine displayed considerable scatter among replicate cores and duplicate biometers. In general, this study concludes that data especially for anaerobic biomineralization of atrazine can be more variable as compared to aerobic conditions and cannot be extrapolated from one agricultural site to another. 相似文献
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《Atmospheric environment(England)》1986,20(5):931-939
The concentration of tin in atmospheric aerosols has been measured at land and ship based sites in the northern and southern hemispheres. Tin concentrations in the northern hemisphere are up to three orders of magnitude greater than those in the southern hemisphere, indicating the importance of anthropogenic inputs to the atmospheric tin cycle. In aerosols sampled in Tallahassee, Florida, tin is correlated with soot carbon in air masses originating in the central U.S., but is not correlated with locally produced soot carbon. Rainwaters collected in Tallahassee, Florida have been analyzed for dissolved tin and major ions. Factor analysis of the results indicates a continental and pollution source for tin. The dissolved fraction of tin in rain represents only a minor component of the deposition flux of tin. Rates of deposition of atmospheric tin are consistent with estimated fluxes of tin to the atmosphere. 相似文献
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Sun-blocking agents including eight UV filters (UVF) and 10 UV light stabilizers (UVLS) were measured in water and sediment collected from 22 rivers, four sewage treatment plant effluents (STPE) and three lakes in Japan. Total sun blocking agents levels ranged from N.D. to 4928 ng/L and from 2.0 to 3422 μg/kg dry wt in surface water and in sediment, respectively. Benzyl salicylate, benzophenone-3, 2-ethyl hexyl-4-methoxycinnamte (EHMC) and octyl salicylate were dominant in surface water receiving wastewater effluents and STPE, although UV-328, benzophenone and EHMC were dominant in other surface water except background sites. Three UVF and nine UVLS were observed from all sediment and their compositions showed similar patterns with UV-328 and UV-234 as the most prevalent compounds. Homosalate, octocrylene, UV-326, UV-327, UV-328 and UV-234 were significantly correlated with Galaxolide® in sediments. Concentrations of UV-327 and UV-328 also had strong correlation between those of UV-326 in sediment. 相似文献
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《Atmospheric environment (Oxford, England : 1994)》2007,41(31):6637-6647
The concentrations of air pollutants such as nitrogen oxides and ozone characterised by very fast chemical reactions can significantly vary within urban street-canyon due to the short distances between sources and receptor. With the primary objective to analyse this issue, NO, NO2, NOx, O3, BTX, and wind flow field were continuously measured for 1 week at two heights (a street-level yard and a 25-m-high rooftop) in an urban canyon in Suzhou (China). The yard ozone concentrations were found to be up to six times lower than on the roof. Different frequency distributions (FD), dynamical and chemical processes of the pollutant variations from yard to roof are discussed to explain the findings. The predominant factors for the dissimilar pollutant vertical diffusion at the two measurement locations were associated to dissimilar fluid-dynamic and heterogeneous removal effects that likely induced dissimilar ozone chemical processes relative to NOx and BTX precursors. 相似文献