南京市农用地土壤中重金属形态特征分析

以南京市农用地土壤为研究对象,采用顺序提取的方法对Cu、Zn、Pb、Cd做化学形态分析,了解不同元素各形态下空间赋存的含量与占比。结果表明,在农用地土壤中,上述4种金属元素所赋存的化学形态活泼性顺序为CdPbCuZn,其中Cd主要为醋酸提取态,Pb主要为可还原态,各占总量的40%以上,具有较高的生物有效性和潜在危害性;Cu与Zn主要为残渣态,占总量的60%左右,生物可利用性较低。由因子分析法可知,土壤p H值越大,Zn与Cd就越趋于向稳定的化学形态转化,土壤有机质含量越高,对Cu与Pb的络合能力就越强,可以降低其环境危害性。     

薄膜扩散梯度技术在重金属生物有效态监测中的应用

重金属生物有效性是评估重金属元素迁移性、生物可利用性和生态影响的关键参数。薄膜扩散梯度技术(DGT)是一种原位被动采样技术,因其具有原位富集性、形态选择性,可提供被监测物质在监测时间段内的平均浓度等优点,可作为生物对重金属摄取的模拟替代物对环境介质中重金属的生物可利用度进行预测,已被广泛应用于环境介质中重金属生物有效性的测定。研究主要介绍了DGT技术的原理、组成和特点,评述了其近年来在水体、土壤、沉积物中重金属生物有效态应用方面的新进展,提出了DGT技术未来要提高抗生物污染能力及寻找可与DGT技术联用的相关技术的观点。     

纳米铁氧化物吸附处理重金属废水的研究进展

概述了用于吸附重金属的主要纳米铁氧化物的种类及其吸附效果,介绍了常见的纳米铁氧化物制备方法及改性方法,讨论了影响纳米铁氧化物吸附重金属的主要因素,并对纳米铁氧化物在水环境保护领域中的研究方向提出了展望:如发展绿色、高效的纳米铁氧化物制备工艺,探讨纳米铁氧化物结构调控和表面功能化对其吸附性能的影响等。     

Investigating the quantitative and qualitative status of effluent in the wastewater treatment plant in Iran Central Iron Ore

The aim of present study was to investigate the quality of the produced effluent from different units of the Iran Central Iron Ore in Bafq city and comparison of effluent with the standards. This study presents the physicochemical and biological parameters data of effluent of three Sequencing batch reactors (SBR) with a capacity of 160 m³?d^?1. Most common parameters include pH, total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP), biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), heavy metals, and total coliforms and fecal coliforms as biological indicators. Then, for each SBR system, the average of each parameter was determined, and results were compared with the standard recommended by the Iranian Environmental Protection Agency. Based on the results, some of the parameters, including BOD₅, COD, and TSS in the wastewater treatment plant (WWTP) effluent, are higher than the permitted amount for discharge to the surface water. Considering the BOD₅, COD, and TSS concentration in WWTPs, the treated wastewater is only suitable for agricultural and irrigation use. Therefore, wastewater produced by Iran Central Iron Ore Co. will need additional treatment to achieve standard quality of water before discharge in surface water and adsorbent well.     

Catalytic oxidation of CO over Pt/Fe3O4 catalysts: Tuning O2 activation and CO adsorption

• Strong metal-support interaction exists on Pt/Fe₃O₄ catalysts. • Pt metal particles facilitate the formation of oxygen vacancies on Fe₃O₄. • Fe₃O₄ supports enhance the strength of CO adsorption on Pt metal particles. The self-inhibition behavior due to CO poisoning on Pt metal particles strongly impairs the performance of CO oxidation. It is an effective method to use reducible metal oxides for supporting Pt metal particles to avoid self-inhibition and to improve catalytic performance. In this work, we used in situ reductions of chloroplatinic acid on commercial Fe₃O₄ powder to prepare heterogeneous-structured Pt/Fe₃O₄ catalysts in the solution of ethylene glycol. The heterogeneous Pt/Fe₃O₄ catalysts achieved a better catalytic performance of CO oxidation compared with the Fe₃O₄ powder. The temperatures of 50% and 90% CO conversion were achieved above 260°C and 290°C at Pt/Fe₃O₄, respectively. However, they are accomplished on Fe₃O₄ at temperatures higher than 310°C. XRD, XPS, and H₂-TPR results confirmed that the metallic Pt atoms have a strong synergistic interaction with the Fe₃O₄ supports. TGA results and transient DRIFTS results proved that the Pt metal particles facilitate the release of lattice oxygen and the formation of oxygen vacancies on Fe₃O₄. The combined results of O₂-TPD and DRIFTS indicated that the activation step of oxygen molecules at surface oxygen vacancies could potentially be the rate-determining step of the catalytic CO oxidation at Pt/Fe₃O₄ catalysts. The reaction pathway involves a Pt-assisted Mars-van Krevelen (MvK) mechanism.     

湛江港表层沉积物重金属的分布及其潜在生态风险评价

测定了湛江港12个表层沉积物样品中重金属Cu、Pb、Zn、Cd和Hg的含量,并与有机质含量进行双变量相关分析,同时应用Hakanson潜在生态风险指数法评价了沉积物重金属综合污染效应。结果表明:湛江港海域沉积物中Cu、Pb、Zn、Cd和Hg的含量范围分别为(9.5～27.2)×10-6、(24.4～68.1)×10-6、(15.7～115.2)×10-6、(未检出～0.202)×10-6和(0.026～0.167)×10-6,平均含量分别为17.6×10-6、36.9×10-6、67.0×10-6、0.065×10-6和0.091×10-6。除Pb与Hg之间,各种重金属元素之间均存在显著或极显著的相关关系。除Pb和Cd之外,各种重金属与有机质之间相关系数较高。Hakan-son潜在生态风险评价结果显示,湛江港表层沉积物重金属的潜在生态风险均较小,属轻微生态危害。5种重金属的潜在生态风险大小依次为:Hg>Pb>Cd>Cu>Zn。     

中国金矿开采区环境汞污染

汞是金矿区环境的特征污染物。金汞同源性导致金矿床一般汞含量偏高,且在以混汞法为代表的提金过程影响下,导致了中国金矿区严重的环境汞污染问题。本文介绍了中国金矿分布与开采及选冶概况,研究了导致金矿区环境汞污染的原因,分析了金矿石选冶过程中汞的释放,并综述了金矿开采所致矿区土壤、水体、大气、生物体中汞污染状况,最后讨论了金矿区汞污染环境管理与生态修复。     

三峡澎溪河回水区消落带岸边土壤重金属污染分布特征

在对澎溪河回水区消落带及岸边土样品中重金属含量和样品理化性质测定的基础上,重点分析了该区域内重金属分布特征,并对重金属元素间的相关性展开研究.同时,应用地累积指数对研究区域污染现状进行评价.结果表明,消落带样品中Cu、Cr、Zn、As、Cd、Pb、Hg的平均含量分别为28.17、59.21、108.98、4.77、2.02、28.85、0.52mg·kg-1;岸边土样品中重金属的含量范围分别为22.32、54.90、98.05、7.87、0.77、22.97、0.94mg·kg-1.Cd是三峡库区污染较严重的重金属元素.相关性分析表明：在消落带样品中,Cd与Zn显著相关（p〈0.01）,Pb、Hg和Cu、As都存在显著的正相关关系,说明这4种重金属元素在接受外来污染时可能存在相似性;在岸边土样品中,Cd与Zn、Cr与Cu、As与Hg显著相关（p〈0.01）,Pb与Cu、Cr、Zn、Cd显著正相关,表明这几种重金属可能有着相似的来源.消落带样品重金属污染程度评价结果为：Cd〉Hg〉Zn〉Pb〉Cu〉As〉Cr,岸边土样品重金属污染程度评价结果为：Hg〉Cd〉Zn〉As〉Pb〉Cu〉Cr,Cd和Hg在个别站位达到了严重污染水平.消落带土壤受人为扰动后会成为水体的二次污染源,因此,消落带土壤重金属对水体的潜在影响不容忽视.     

贵州名优茶产区土壤-茶叶中重金属污染及迁移

选择贵州省云雾、都匀、湄潭3个典型名优茶产区,采集土壤和茶叶样品进行重金属检测分析。结果表明:贵州省茶园土壤主要重金属污染元素为Cd和Hg,3个茶产区中,湄潭茶产区土壤Cd的超标率最高,达到39.4%,都匀茶产区土壤Hg超标率最高,为24.2%。土壤Cd平均含量表现为都匀茶产区>湄潭茶产区>云雾茶产区,超标率表现为湄潭茶产区>都匀茶产区>云雾茶产区;土壤Hg含量和超标率均表现为都匀茶产区>湄潭茶产区>云雾茶产区。贵州省3个典型名优茶产区茶叶重金属含量均低于国家标准限量,茶叶中Cd、Hg、Cu、Pb含量随土壤中Cd、Hg、Cu、Pb含量增大而增大,不同重金属在茶叶中的富集系数为Cd>Hg>Cu>Pb>Cr>As。     

pH-dependent leaching behaviour and other performance properties of cement-treated mixed contaminated soil

Portland cement has been widely used for stabilisation/solidification (S/S) treatment of contaminated soils. However, there is a dearth of literature on pH-dependent leaching of contaminants from cement-treated soils. This study investigates the leachability of Cu, Pb, Ni, Zn and total petroleum hydrocarbons (TPH) from a mixed contaminated soil. A sandy soil was spiked with 3000 mg/kg each of Cd, Cu, Pb, Ni and Zn, and 10,000 mg/kg of diesel, and treated with ordinary Portland cement (CEM I). Four different binder dosages, 5%, 10%, 15% and 20% (m/m) and different water contents ranging from 13%-19% dry weight were used in order to find a safe operating envelope for the treatment process. The pH-dependent leaching behaviour of the treated soil was monitored over an 84-day period using a 3-point acid neutralisation capacity (ANC) test. The monolithic leaching test was also conducted. Geotechnical properties such as unconfined compressive strength (UCS), hydraulic conductivity and porosity were assessed over time. The treated soils recorded lower leachate concentrations of Ni and Zn compared to the untreated soil at the same pH depending on binder dosage. The binder had problems with Pb stabilisation and TPH leachability was independent of pH and binder dosage. The hydraulic conductivity of the mixes was generally of the order, 10^-8 m/sec, while the porosity ranged from 26%-44%. The results of selected performance properties are compared with regulatory limits and the range of operating variables that lead to acceptable performance described.