Comparative cytotoxicity of fourteen trivalent and pentavalent arsenic species determined using real-time cell sensing

The occurrence of a large number of diverse arsenic species in the environment and in biological systems makes it important to compare their relative toxicity. The toxicity of arsenic species has been examined in various cell lines using different assays, making comparison difficult. We report real-time cell sensing of two human cell lines to examine the cytotoxicity of fourteen arsenic species: arsenite(As~Ⅲ), monomethylarsonous acid(MMA~Ⅲ) originating from the oxide and iodide forms, dimethylarsinous acid(DMA~Ⅲ), dimethylarsinic glutathione(DMAG~Ⅲ), phenylarsine oxide(PAO~Ⅲ), arsenate(AsV), monomethylarsonic acid(MMA~Ⅴ), dimethylarsinic acid(DMA~Ⅴ),monomethyltrithioarsonate(MMTTA~Ⅴ), dimethylmonothioarsinate(DMMTA~Ⅴ),dimethyldithioarsinate(DMDTA~Ⅴ), 3-nitro-4-hydroxyphenylarsonic acid(Roxarsone, Rox),and 4-aminobenzenearsenic acid(p-arsanilic acid, p-ASA). Cellular responses were measured in real time for 72 hr in human lung(A549) and bladder(T24) cells. IC50 values for the arsenicals were determined continuously over the exposure time, giving rise to IC50 histograms and unique cell response profiles. Arsenic accumulation and speciation were analyzed using inductively coupled plasma-mass spectrometry(ICP-MS). On the basis of the 24-hr IC50 values, the relative cytotoxicity of the tested arsenicals was in the following decreasing order: PAO~Ⅲ? MMA~Ⅲ≥ DMA~Ⅲ≥ DMAG~Ⅲ≈ DMMTA~Ⅴ≥ As~Ⅲ? MMTTA~Ⅴ AsV DMDTA~ⅤDMA~Ⅴ MMA~Ⅴ≥ Rox ≥ p-ASA. Stepwise shapes of cell response profiles for DMA~Ⅲ, DMAG~Ⅲ,and DMMTA~Ⅴcoincided with the conversion of these arsenicals to the less toxic pentavalent DMA~Ⅴ. Dynamic monitoring of real-time cellular responses to fourteen arsenicals provided useful information for comparison of their relative cytotoxicity.     

大型商圈安全评价体系及案例研究*

为整体评价大型商圈的安全性,结合公共安全科技三角形理论,从突发事件的危险性、承灾载体的脆弱性、应急能力3方面构建大型商圈安全评价指标体系,通过网络分析法和模糊综合评价法确定指标间权重系数,对大型商圈进行安全风险评价。结果表明:体系全面考虑了大型商圈安全风险影响因素及其内在关系,可为大型商圈安全评价体系构建和定量评估提供参考。     

Oxidation and detoxification of pentachlorophenol in aqueous phase by ozonation

The degradation and detoxification performance of ozonation in treating pentachlorophenol (PCP) contaminated wastewater was determined. All experiments were conducted in a bench scale glass column equipped with ceramic diffuser and a lab-scale ozone generator under ambient temperature and pH 7. The decomposition rate of PCP in this study was primarily controlled by the ozone mass transfer rate from gas to liquid phases. Principal intermediates found were 2,3,4,6- and 2,3,5,6-tetrachlorophenols (TeCP) and phenol. PCP seems to be more vulnerable to ozone than its intermediates. A bioluminescence technique was used to evaluate the toxicity of PCP with Vibrio fisheri NRRL B-11177 as the test bacterium, and the EC(50) of PCP was found to be 1.0 mg l(-1). Detoxification occurred as the PCP and TeCP reacted with ozone and decomposed to less chlorinated congeners and phenol.     

从电镀锌废渣中回收制备锌盐的研究

研究了以含锌废渣为原料、制备锌产品的工艺条件。实验主要对酸浸取，氧化除铁、锗和置换除去重金属元素等过程的工艺条件进行了研究。制得碱式碳酸锌和氧化锌两种锌产品，其纯度分别大于96％和95％。锌回收率达到80％以上。     

投影寻踪聚类分析在环境质量综合评价中的应用

介绍了投影寻聚类方法用于环境质量综合评价的基本原理，并将该方法成功用于大气环境质量综合评价分析中，与其他综合评价方法相比，投影寻踪聚类分析不但可以做出环境质量的综合评价，而且还可以根据投影分量值分析相应指标影响环境质量的重要性程度，找出影响环境质量的主要因素。     

Field demonstration of in situ immobilization of soil Pb using P amendments

A long-term field-scale demonstration project on the feasibility of using P to immobilize Pb in a Pb-contaminated urban soil was conducted. Phosphate was applied at an average rate of 3040 mg P/kg soil based on a P/Pb molar ration of 4.0, with four treatments: T₀, no P application; T₁, H₃PO₄ only; T₂, 1/2 H₃PO₄+1/2 CaH₂PO₄; and T₃, 1/2 H₃PO₄+1/2 phosphate rock. Soil samples were collected and analyzed 220 days after the P applications. For all P treatments, toxicity characteristic leaching procedure (TCLP) extractable Pb levels in surface soils (0-10 cm) were reduced to below 5.0 mg Pb/l, with T₂ also effective in reducing the TCLP Pb level in subsurface soils (10-30 cm, <4.63 mg/l). Sequential extraction analysis indicates that P was effective in transforming soil Pb from non-residual fractions to a residual fraction. Such a transformation was mainly through dissolution of Pb associated with carbonate fraction and precipitation of pyromorphite-like minerals, which were confirmed using X-ray diffraction (XRD). Among these three treatments, T₃ was the most effective in reducing Pb mobility and minimizing P and Pb leaching in the soil. Our research clearly demonstrates that P amendments were effective in immobilizing Pb in contaminated soil.     

浅析“城市环境综合整治定量考核”制度

分析了"城市环境综合整治定量考核"制度在指标设置、考核标准及实施过程中存在的问题,指出其对"城市环境综合整治定量考核"结果的公正性产生了影响。提出在"十二五"城考指标调整中应适当增加环境质量的比重,体现对不同地区、不同级别的城市采取分级管理、分类指导原则,并加强对环保工作的规范化和能力建设的考核,进一步提高城市环境管理水平的对策与建议。     

The enhancement of photodegradation efficiency using Pt-TiO2 catalyst

The residues from the extraction of lead/zinc (Pb/Zn) ores of most Pb/Zn mines are permanently stored in tailings ponds, which require revegetation to reduce their environmental impact. This can only be done if the main constraints on plant establishment are evaluated. This can readily be done by field and greenhouse studies.

To test this, the properties of different tailings from Lechang Pb/Zn mine located at the north of Guangdong Province in southern China have been studied. Physical and chemical properties including concentrations of metals (Pb, Zn, Cd and Cu) in the tailings and soils collected from different sites have been measured. The results showed that tailings contain low nitrogen (0.016–0.075%), low-organic matter (0.58–1.78%), high salt (3.55–13.85 dS/m), and high total and diethylene–tetramine–pentaacetic acid (DTPA)-extractable metal concentrations (total: 1019–1642 μg g⁻¹ Pb, 3078–6773 μg g⁻¹ Zn, 8–23 μg g⁻¹ Cd, and 85–192 μg g⁻¹ Cu; DTPA-extractable: 59–178 μg g⁻¹ Pb, 21–200 μg g⁻¹ Zn, 0.30–1.5 μg g⁻¹ Cd, and 4.3–12 μg g⁻¹ Cu). Aqueous extracts of tailings/soils (10%, 20% and 30%, w/v) from different sites were prepared for testing their effects on seed germination and root elongation of a vegetable crop Brassica chinensis and a grass species Cynodon dactylon. It was found that root elongation provided a better evaluation of toxicity than seed germination. The ranking of toxicity using root elongation was: high-sulfur tailings>tailingdam>sparsely vegetated tailings>densely vegetated tailings>mountain soil for both plants. This order was consistent with DTPA-extractable Pb contents in the tailings and soils. B. chinensis seedlings were then grown in the mixtures of different proportions of tailings and farm soil for 4 weeks, and the results (dry weights of seedlings) were in line with the root elongation test. All these demonstrated that heavy metal toxicity, especially available Pb, low content of nutrient, and poor physical structure were major constraints on plant establishment and colonization on the Pb/Zn mine tailings.     

Oxidation of acid-volatile sulfide in surface sediments increases the release and toxicity of copper to the benthic amphipod Melita plumulosa

Acid-volatile sulfides (AVS) are an important metal-binding phase in sediments. For sediments that contain an excess of AVS over simultaneously extracted metal (SEM) concentrations, acute or chronic effects should not result from the metals Cd, Cu, Ni, Pb and Zn. While AVS phases may exist in surface sediments, the exposure to dissolved oxygen may oxidize the AVS and release metals to more bioavailable forms. We investigated the role of oxidation of AVS, and specifically copper sulfide phases, in surface sediments, in the toxicity to juveniles of the epibenthic amphipod, Melita plumulosa. Sediments containing known amounts of copper sulfide were prepared either in situ by reacting dissolved copper with AVS that had formed in field sediments or created in sediments within the laboratory, or by addition of synthesised CuS to sediments. Regardless of the form of the copper sulfide, considerable oxidation of AVS occurred during the 10-d tests. Sediments that had a molar excess of AVS compared to SEM at the start of the tests, did not always have an excess at the end of the tests. Consistent with the AVS-SEM model, no toxicity was observed for sediments with an excess of AVS throughout the tests. However, the study highlights the need to carefully consider the changes in AVS concentrations during tests, and that measurements of AVS and SEM concentrations should carefully target the materials to which the organisms are being exposed throughout tests, which in the case of juvenile M. plumulosa is the top few mm of the sediments.     

Identifying the cause of toxicity in an algal whole effluent toxicity study - an unanticipated toxicant

Toxicity was observed in whole effluent toxicity (WET) studies with the freshwater alga, Pseudokirchneriella subcapitata, in three consecutive monthly studies, (NOEC = 50-75%). Toxicity was not observed to Ceriodaphnia dubia or the fathead minnow, Pimephales promelas in concurrent studies. Selected toxicity identification evaluation (TIE) tests were conducted in a tiered approach to eliminate possible toxicants and progressively identify the causative agent. Filtration following alkaline adjustment (pH 10 or 11) was effective in eliminating significant growth effects and also reduced phosphate concentration. The TIE studies confirmed that the observed effluent toxicity was caused by excess ortho-phosphate in the effluent not by overstimulation or related to unfavorable N:P ratios; but due to direct toxicity. The 96-h 25% inhibition concentration (IC25) of ortho-phosphate to P. subcapitata was 3.4 mg L⁻¹ while the maximum acceptable toxicant concentration was 4.8 mg L⁻¹. This study illustrates the value of multi-species testing and also provides an example of an effective TIE using algae identifying an unanticipated toxicant.