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1.
Whalley Caroline Hursthouse Andrew Rowlatt Steve Iqbal-Zahid Parveen Vaughan Huw Durant Ruth 《Water, air, and soil pollution》1999,112(3-4):389-405
Historically, solid waste from chromite ore processing has been disposed of at a number of sites in Glasgow, Scotland. Leachate from these sites has been implicated as a source of chromium (Cr) contamination to both groundwaters and stream waters in the south east area of the city. In this study, chromium speciation has been determined in ground-, stream-, river- and pore waters, to assess the extent of contamination and the associated risk. The speciation of chromium is important, as the trivalent species of chromium (Cr(III)) is an essential form of the element, while hexavalent chromium (Cr(VI)) is a known carcinogen to humans via inhalation. Concentrations of total chromium have also been determined in sediments from the River Clyde, to assess the significance of local concentrations relative to those elsewhere in the catchment. High concentrations of Cr(VI) were found in groundwaters and streamwaters in the area immediately surrounding the contaminated sites, and high concentrations of chromium were also found in River Clyde sediments downstream of these sites. However, these concentrations rapidly decrease away from the chromium-contaminated south eastern side of the city. Data from porewaters suggest that some reduction of Cr(VI) occurs naturally in the sediments, indicating that the risk posed by high concentrations of Cr(VI) should be decreased over the longer term. 相似文献
2.
铬(Cr)污染的迁移和环境毒性主要取决于其化学形态。在环境中,如果移动性及毒性较大的Cr(Ⅵ)能被还原为移动性及毒性较小的Cr(Ⅲ),并且还原速率大于污染速率,那么对铬污染的自然生态修复治理是可行的。铬在氧化还原过程中,存在着同位素动力学分馏效应,致使同位素比率发生移动,移动的大小和反应进程有关,服从Reyleigh关系方程。因此,利用同位素测定可以确定Cr(Ⅵ)的归宿,用于铬(Cr)污染自然修复的监测。本文就环境铬污染自然生态修复中,应用同位素原位分析法进行监测的基本原理、分析过程及应用的可行性进行了阐述。 相似文献
3.
Ramesh C. Patra Seidu Malik Michael Beer Mallavarapu Megharaj Ravi Naidu 《Soil biology & biochemistry》2010,42(10):1857-1863
Hexavalent chromium [Cr(VI)] is highly toxic, teratogenic and carcinogenic to man and other animals. Some bacterial species have the ability to reduce Cr(VI) to a stable speciation state of trivalent chromium [Cr(III)], which is insoluble and comparatively less toxic. Therefore, the reduction of Cr(VI) thus provides potential as a means for environmental bioremediation of Cr(VI) pollution. In the present study bacteria isolated from chromium and diesel contaminated sites were found to have the ability to rapidly reduce highly toxic concentrations of Cr(VI) to Cr(III) when grown in minimal medium supplemented with glucose as the sole carbon source. Partial chromate reductase gene sequences were retrieved after PCR amplification of genomic DNA extracted from three Gram positive isolates which were highly similar (>99% sequence similarity) to chromate reductase genes found in Gram negative bacteria, more specifically those identified from Escherichia coli and Shigella spp. whole-genome studies. The isolated bacteria were putatively identified by 16S rRNA gene sequencing as Arthrobacter aurescens strain MM10, Bacillus atrophaeus strain MM20, and Rhodococcus erythropolis strain MM30. 相似文献
4.
Andrea Ertani Anna Mietto Maurizio Borin Serenella Nardi 《Water, air, and soil pollution》2017,228(5):190
The mobility and distribution of metals in the environment is related not only to their concentration but also to their availability in the environment. Most chromium (Cr) exists in oxidation states ranging from 0 to VI in soils but the most stable and common forms are Cr(0), Cr(III), and Cr(VI) species. Chromium can have positive and negative effects on health, according to the dose, exposure time, and its oxidation state. The last is highly soluble; mobile; and toxic to humans, animals, and plants. On the contrary, Cr(III) has relatively low toxicity and mobility and it is one of the micronutrients needed by humans. In addition, Cr(III) can be absorbed on the surface of clay minerals in precipitates or complexes. Thus, the approaches converting Cr(VI) to Cr(III) in soils and waters have received considerable attention. The Cr(III) compounds are sparingly soluble in water and may be found in water bodies as soluble Cr(III) complexes, while the Cr(VI) compounds are readily soluble in water. Chromium is absorbed by plants through carriers of essential ions such as sulfate. Chromium uptake, accumulation, and translocation, depend on its speciation. Chromium shortage can cause cardiac problems, metabolic dysfunctions, and diabetes. Symptoms of Cr toxicity in plants comprise decrease of germination, reduction of growth, inhibition of enzymatic activities, impairment of photosynthesis and oxidative imbalances. This review provides an overview of the chemical characteristics of Cr, its behavior in the environment, the relationships with plants and aspects of the use of fertilizers. 相似文献
5.
Hexavalent chromium (Cr(VI)), which has been classified as a Group A human carcinogens list by the United States Environmental Protection Agency, possesses stronger biological toxicity, and its discharge into farmland has become a pressing environmental problems. To screen the cost-efficient Cr(VI)-contaminated soil in situ amended materials, the effects of ordinary zero-valent iron (ZVI), nanoscale zero-valent iron (nZVI), biochar (B), biochar/zero-valent iron (BZVI), and biochar/nanoscale zero-valent iron (BnZVI) on the immobilization of Cr(VI) in spiked soil (Cr(VI) = 325 mg kg?1, Crtotal = 640 mg kg?1) were compared in this paper. After 15 days remediation by those materials, toxicity characteristic leaching procedure and physiological-based extraction test showed that the Cr(VI) leachability and bioaccessibility were reduced by 14–92% and 4.3–92% respectively, and the order of immobilization was found to be nZVI > BnZVI > BZVI > ZVI > B. Moreover, sequential extraction procedure indicated that all materials can increase the proportion of the residual Cr, and nZVI had the most significant effect. Plant seedling growth test proved that the nanoscale zero-valent iron was able to reduce the toxicity of chromium in plants greatly in a short time, while BnZVI treatment is more favorable to the growth of plants. To sum up, the nano zero-valent iron and biochar combined treatment not only removed Cr(VI) and immobilized total chromium efficiently but also enabled plant growth in relative high chromium-containing soil. 相似文献
6.
Liliana Morales-Barrera Eliseo Cristiani-Urbina 《Water, air, and soil pollution》2008,187(1-4):327-336
A fungal strain possibly capable of removing hexavalent chromium was to be isolated from industrial effluent from a leather factory located in the city of Guadalajara, state of Jalisco, Mexico. The strain was identified as Trichoderma inhamatum by the D1/D2 domain sequence of the 28S rDNA gene. Batch cultures of T. inhamatum in media containing initial Cr(VI) concentrations from 0.83 to 2.43 mM Cr(VI) were prepared. Experimental results suggest that the fungus is capable of transforming hexavalent chromium to trivalent chromium; a transformation of a highly toxic contaminant to a low toxic form. The specific and volumetric rates of Cr(VI) reduction by T. inhamatum cultures decreased as the initial Cr(VI) concentration increased. The fungus exhibited a remarkable capacity to tolerate and completely reduce Cr(VI) concentrations up to 2.43 mM. These results indicate that the T. inhamatum fungal strain may have potential applications in bioremediation of Cr(VI)-contaminated wastewaters. 相似文献
7.
Extensive use of chromium in industry has caused environmental contamination. Chromium-resistant bacteria are capable of reducing toxic Cr (VI) to less toxic Cr (III). Eight isolates, which can grow on LB agar containing 500 mg/L of Cr (VI), were isolated from soil samples of iron mineral area. The bacterial isolates were identified as Bacillus sp. by the 16S rRNA gene sequences. Phylogenetic tree analysis indicates the isolates can be divided into two groups. The bacterial isolates can be resistant to other heavy metals and reduce Cr (VI) at different levels. One bacterial isolate (MDS05), which can tolerate 2500 mg/L Cr (VI) and was able to reduce almost 100% of Cr (VI) at the concentration of 10 mg/L in 24 h, was selected to study the effects of some environmental factors such as pH, temperature, and time on Cr (VI) reduction and growth. The cell growth of MDS05 was affected by the presence of Cr (VI), especially at the concentration of 100 mg/L. It reduced more amount of Cr (VI) under a wide range of concentrations from 5 to 50 mg/L, and reduction was optimum at 37 °C and pH 8. MDS05 showed great promise for use in Cr (VI) detoxification under a wide range of environmental conditions. 相似文献
8.
Disposal of chromium(Cr) hexavalent form,Cr(VI),in soils as additions in organic fertilizers,liming materials or plant nutrient sources can be dangerous since Cr(VI) can be highly toxic to plants,animals,and humans.In order to explore soil conditions that lead to Cr(VI) generation,this study were performed using a Paleudult(Dystic Nitosol) from a region that has a high concentration of tannery operations in the Rio Grande do Sul State,southern Brazil.Three laboratory incubation experiments were carried out to examine the influences of soil moisture content and concentration of cobalt and organic matter additions on soil Cr(VI) formation and release and manganese(Mn) oxide reduction with a salt of chromium chloride(CrCl 3) and tannery sludge as inorganic and organic sources of Cr(III),respectively.The amount of Cr(III) oxidation depended on the concentration of easily reducible Mn oxides and the oxidation was more intense at the soil water contents in which Mn(III/IV) oxides were more stable.Soluble organic compounds in soil decreased Cr(VI) formation due to Cr(III) complexation.This mechanism also resulted in the decrease in the oxidation of Cr(III) due to the tannery sludge additions.Chromium(III) oxidation to Cr(VI) at the solid/solution interface involved the following mechanisms:the formation of a precursor complex on manganese(Mn) oxide surfaces,followed by electron transfer from Cr(III) to Mn(III or IV),the formation of a successor complex with Mn(II) and Cr(VI),and the breakdown of the successor complex and release of Mn(II) and Cr(VI) into the soil solution. 相似文献
9.
The ground water of Leon valley, Central Mexico, is contaminated with chromium. A study was carried out to determine the main physico-chemical interactions between chromium and the aquifer solid matrix in the most polluted area. Five boreholes, 30 m deep, were drilled and used as piezometers. Unaltered solid cores were analyzed for Cr(VI), total Cr, Fe and Mn. Cr(VI) was determined in the water from the piezometers. We conclude that reduction of Cr(VI) by iron is important, adsorption of Cr(VI) by sand and gravel layers is negligible, and adsorption by silt and clay layers is significant in the saturated and unsaturated zones. In the saturated zone hexavalent chromium distributes preferentially in the water phase oxidation of chromium by manganese was not detected. A correlation between chromium, manganese and iron concentrations was observed for the aquifer solid matrix in this area, when the source of chromium was not anthropogenic. 相似文献
10.
茶树废弃物引起的环境破坏和病虫害爆发问题日益突出,对其进行无害化和资源化利用具有重要意义。该研究以修剪的茶树枝叶提取液作为还原剂和封端剂,以提取后的残渣作为炭源,成功制备了一种可高效去除水中六价铬(Cr(Ⅵ))的生物炭负载纳米零价铁复合材料(nanoscale zero-valent iron embedded tea leaves,TLBC-nZVI)。分析了材料用量、溶液初始pH值和温度等对Cr(Ⅵ)去除效果的影响;利用扫描电子显微镜结合能量色散X射线光谱仪(SEMEDS)、傅立叶变换红外光谱仪(FTIR)、X射线粉晶衍射仪(XRD)和X射线光电子能谱仪(XPS)等对材料进行表征,结合吸附动力学、吸附等温线和吸附热力试验探讨了去除机制。结果表明酸性条件、高温、增加材料用量有利于TLBC-nZVI对Cr(Ⅵ)的去除。TLBC-nZVI吸附过程符合准二级动力学模型、颗粒内扩散模型和Freundlich吸附等温模型,该吸附是自发的化学吸热过程。TLBC-nZVI与Cr(Ⅵ)的反应机制为吸附在材料上的Cr(Ⅵ)被零价铁(Fe0)和还原性官能团还原为三价铬(Cr(Ⅲ))... 相似文献
11.
Removal of selenate in river and drainage waters by Citrobacter braakii enhanced with zero-valent iron 总被引：1，自引：0，他引：1
A cost-effective remediation method is needed to remove selenium (Se) from Se-contaminated water. In this study, a selenate [Se(VI)]-reducing bacterium, Citrobacter braakii, that is capable of using molasses as a carbon source to reduce Se(VI) from natural river and drainage waters was isolated. During an 8-day experiment, 87-97% of the added Se(VI) in New River water and White River water, California, was reduced to elemental Se [Se(0)] or transformed to organic Se. In highly saline drainage water, removal of Se(VI) by C. braakii was limited, with 20% Se(VI) removal in a 7-day experiment. Addition of zero-valent iron (ZVI) into these waters along with C. braakii inoculation significantly enhanced the removal of Se(VI) and reduced the formation of organic Se. This study suggests that the combination of a bacterial treatment using inexpensive molasses and ZVI can effectively remove Se from natural river water and agricultural drainage waters. 相似文献
12.
Alma Rosa Netzahuatl-Muñoz Flor de María Guillén-Jiménez Benjamín Chávez-Gómez Thelma Lilia Villegas-Garrido Eliseo Cristiani-Urbina 《Water, air, and soil pollution》2012,223(2):625-641
Solution pH is among the most important parameters that influence heavy metal biosorption. This work presents a kinetic study
of the effects of pH on chromium biosorption onto Cupressus lusitanica Mill bark from aqueous Cr(VI) or Cr(III) solutions and proposes a mechanism of adsorption. At all assayed contact times,
the optimum pH for chromium biosorption from the Cr(III) solution was 5.0; in contrast, optimum pH for chromium biosorption
from the Cr(VI) solution varied depending on contact time. The kinetic models that satisfactorily described the chromium biosorption
processes from the Cr(III) and Cr(VI) solutions were the Elovich and pseudo second-order models, respectively. Diffuse reflectance
infrared Fourier transform spectroscopy studies suggest that phenolic compounds present on C. lusitanica Mill bark play an important role in chromium biosorption from the Cr(III) solution. On the other hand, chromium biosorption
from the Cr(VI) solution involved carboxyl groups produced on the bark by redox reactions between oxygen-containing groups
and Cr(VI), and these were in turn responsible for the biosorption of Cr(III) produced by Cr(VI) reduction. 相似文献
13.
Mojdeh Owlad Mohamed Kheireddine Aroua Wan Ashri Wan Daud Saeid Baroutian 《Water, air, and soil pollution》2009,200(1-4):59-77
Cr(VI) is a well-known highly toxic metal, considered a priority pollutant. Industrial sources of Cr(VI) include leather tanning, cooling tower blowdown, plating, electroplating, anodizing baths, rinse waters, etc. This article includes a survey of removal techniques for Cr(VI)-contaminated aqueous solutions. A particular focus is given to adsorption, membrane filtration, ion exchange, and electrochemical treatment methods. The primary objective of this article is to provide recent information about the most widely used techniques for Cr(VI) removal. 相似文献
14.
The short term acute toxicity of potassium chromate, potassium dichromate and chromium sulphate has been compared in a simple microbial bioassay. The test parameters were, decrease in viability, genotoxicity and metal uptake. The LC50 values of Cr(III), dichromate Cr(VI) and chromate Cr(VI) for Escherichia coli were 16, 10 and 1.2 μg mL?1, respectively. Among the test substances potassium chromate was most toxic and showed no bioaccumulation while potassium dichromate was less toxic but resulted in significant bioaccumulation. Chromium sulphate was least toxic. As evident from loss of plasmid, genotoxicity was exhibited only by Cr (VI). 相似文献
15.
Bader J. L. Gonzalez G. Goodell P. C. Pillai S. D. Ali A. S. 《Water, air, and soil pollution》1999,109(1-4):263-276
Chromium-containing industrial effluents are primarily responsible for environmental contamination by toxic and highly mobile, hexavalent chromium. The dilution plate-count method, using media amended with Cr(VI) at concentrations ranging from 0 to 1000 mg L-1, was used to compare the sizes of Cr(VI)-resistant bacterial populations from a soil contaminated with 25 100 mg kg-1 total Cr [12 400 mg kg-1 Cr(VI)] to those isolated from a slightly contaminated soil (99.6 mg kg-1 total Cr) and two other soils without any history of Cr contamination. Bacterial populations resistant to 500 mg L-1 Cr(VI) were isolated from all soils except the heavily contaminated soil. To determine whether Cr-resistant bacterial populations were indigenous to both the contaminated and the uncontaminated soils, enrichment cultures containing Cr(VI) at concentrations ranging from 0 to 1000 mg L-1 were employed. Bacterial populations, as high as 105 (colony forming units) CFU g-1 soil, tolerant of 500 mg L-1 Cr(VI) were isolated from all soils within 48 h of enrichment suggesting that the presence of aerobic Cr(VI)-resistant bacterial populations is unrelated to contamination levels or contamination history. However, identification of these resistant bacteria using fatty acid profiles was unsuccessful suggesting that these populations may have unique characteristics. Fungal colonies resistant to 1000 mg L-1 Cr(VI) were routinely isolated from both uncontaminated and contaminated soils. The results suggest that Cr-resistant microorganisms may be present in soils, even those with no history of Cr contamination. 相似文献
16.
The potential application of commercial coffee as a source of electron donors for detoxifying hexavalent chromium [Cr(VI)]-contaminated water was investigated. Various amounts of coffee were reacted with 50 mg/L of artificially prepared Cr(VI)-contaminated water, and the Cr(VI) concentration was monitored as a function of the reaction time using the diphenylcarbazide colorimetric method with an Aquamate 8000 UV-Vis spectrophotometer at a 540-nm wavelength. When the ratio of the coffee mass applied to the volume of Cr(VI) solution was 75 g/L, more than 80% of the initial Cr(VI) disappeared within 5 min of reaction time, and the Cr(VI) concentration became lower than the detection limit of 1 mg/L within 20 min. More Cr(VI) disappeared as more coffee was introduced. In general, smaller particles of coffee were more effective at Cr(VI) reduction, but the advantage that particle size conferred disappeared once the coffee particle size was smaller than 125 μm. As a result, the reduction of the Cr(VI) in the solution was not considered to result from the surface catalytic reduction but by the electron transfer from the electron donors released from the applied coffee. 相似文献
17.
Yu. N. Vodyanitskii 《Eurasian Soil Science》2009,42(5):507-515
In the last decades, the chromium clarke in the world’s soils has been revised and reduced; at present, it is equal to 70 mg/kg. No maximal permissible concentration is accepted for the total chromium content in the soils of Russia; it appears reasonable to use the Western European and North American standards in Russia and to take the average value of the maximal permissible concentration equal to 200 mg Cr/kg. Chromium toxicity depends on its oxidizing status. The hazardous effect decreases with the reduction of Cr(VI) to Cr(III). There are various chemical reducers of Cr(VI), including sulfides, dissolved organic substance, aqueous Fe(II) and minerals enriched in Fe(II), and Fe(0). As-containing ore tailings represent a powerful source of technogenic arsenic. Significant environment contamination with natural As is registered in a number of Asian countries. The maximal permissible concentration of total arsenic is equal to 2 mg/kg in Russian soils; it is probably underestimated, because it is lower than the As clarke in soil (5 mg/kg). The approximately permissible concentration (APC) values for As look more reasonable. Arsenic toxicity depends on its oxidation degree: As(III) is 2–3 times more toxic than As(V). 相似文献
18.
《Communications in Soil Science and Plant Analysis》2012,43(11-12):1503-1518
Abstract Phytotoxicity, due to chromium [Cr (VI)] additions from low to very high levels in a swell–shrink clayey soil (Haplustert), in maize and spinach was studied in a pot culture experiment. Six levels of Cr (VI) (0, 5, 10, 25, 50, and 75 mg kg?1 soil) for maize and five levels for spinach (0, 2, 5, 10, and 25 mg kg?1 soil) were applied singly and in combination with two doses (0 and 20 t ha?1) of city compost. At levels of more than 75 mg Cr (VI) kg?1 soil for maize there was virtually no growth after germination, whereas 25 mg Cr (VI) kg?1 soil hindered the germination of spinach crop. Initial symptoms of Cr (VI) toxicity appeared as severe wilting of the tops of treated plants. Maize plants suffering from severe Cr (VI) toxicity had smaller roots and narrow brownish red leaves covered with small necrotic spots. In spinach, severe chlorosis was observed in leaves. Higher levels of Cr (VI) inhibited the growth and dry‐matter yield of the crops. However, application of city compost alleviated the toxic effect of Cr (VI). The concentration of Cr (VI) in plant parts increased when Cr (VI) was applied singly but decreased considerably when used in combination with city compost. There was evidence of an antagonistic effect of Cr (VI) on other heavy‐metal (Mn, Cu, Zn, and Fe) concentrations in plant tops. Thus, when Cr (VI) concentration increases, the concentration of other beneficial metals decreases. Chromium (VI) concentration in maize roots ranged from traces (control) to 30 mg kg?1and were directly related to soil Cr (VI) concentration. At 25 mg Cr (VI) kg?1 soil, yield of maize was reduced to 41% of control plants, whereas in spinach, 10 mg Cr (VI) kg?1 soil caused a 33% yield reduction. Experimental results revealed that the maize top (cereal) is less effective in accumulating Cr (VI) than spinach (leafy vegetables). Laboratory studies were also conducted to know Cr (VI) sorption capacity of a swell–shrink clayey soil with and without city compost, and it was found that Cr (VI) sorption reaction was endothermic and spontaneous in nature. 相似文献
19.
20.
Chung Jong-Bae Burau Richard G. Zasoski Robert J. 《Water, air, and soil pollution》2001,128(3-4):407-417
Soluble chromate concentrations as high as 200 μg Cr L-1 have been reported in water samples from monitoringwells tapping alluvial deposits allegedly contaminated bylaboratory waste as well as control wells off site andupgradient (shallow aquifer) near Davis California, U.S.A. In this report we present evidence that these Cr(VI) levelscould have been generated by geogenic processes rather thanby anthropogenic inputs. We tested the hypothesis thatnative Cr(III) has been and can be oxidized to chromate bynative manganese oxides. Twenty-three drill core samples(all unsaturated) were retrieved from depths varying from1.5 to 22.5 m in 6 different wells. Visible nodules ofMnO2 were dispersed throughout many of the samples andcarbonates were also present. Sample pH values averagedabout 8.0 and organic C was mostly less than 1.0 g kg-1. Total Mn and Cr averaged 835 and 191 mg kg-1respectively. All samples had the capability to oxidizeadded Cr(III) to Cr(VI). To determine the inherent capabilityof the samples to produce Cr(VI) from native Cr(III), subsamples were extracted with 5 mM CaSO4 plus 5 mM MgSO4 until Cr(VI) was no longer detected. After freeze-drying, deionized-distilled water was added to theleached samples to approximately field capacity (0.03 MPa). Freeze drying did not generate Cr(VI). These samples wereincubated in polyethylene film bags at room temperature inthe dark. After 1 week incubation, water in the samples wasextracted by centrifugation and the extracts were analyzedfor Cr(VI). All of the samples generated Cr(VI), and theconcentrations in the extracts ranged from 20 to 100 μg Cr L-1. Total chromium, endemic chromium VI and chromium VI generated in leached samples were not statistically different between samples from onsite and control samples taken offsite and upgradient in respect to the shallowest aquifer. 相似文献