Mobility of arsenic and environmentally significant elements in mine tailings following liming

Remediation of a legacy tin-tailings site in northeast Tasmania, Australia was carried out by statutory authorities. This study evaluated the fate of As and other deleterious trace metals Cd, Cu, Fe and Zn (among others) following the application of lime and fertiliser. Arsenic concentrations in the tailings ranged from 86 mg/kg to 0.26 wt%. Surface application of lime resulted in a 100-fold reduction in dissolved As concentrations in on-site surface waters; from an average of 196 µg/L prior to lime addition, to between 2.0 and 7.4 µg/L post-amendment. The concentration of other deleterious elements, however, varied between dry and wet cycles. The concentrations of Cd, Cu and Zn in surface waters were high and similar to pre-remediation levels during dry conditions (0.4, 13.5 and 6.1 mg/L, respectively), and only below freshwater ecosystem protection values during wet conditions. Bioaccumulation of Cd was observed in the naturally occurring coloniser, Juncus pallidus, with 4–5 times more Cd in the above-ground biomass relative to the tailings. Ferric arsenate (scorodite) was the dominant source of As identified in the tailings mineralogy. Hydrous ferric oxides and Fe-bearing cassiterite were also identified as hosting As. The pH increase in the surface lime-amended tailings was inferred to result in precipitation of observed hydrous ferric oxides, hematite and goethite, providing high-surface area for adsorption of arsenate onto positively charged surfaces. Jarosite was observed in both the surface lime-amended and subsurface non-amended tailings and suggests a continued supply of acidity to the pore waters despite the application of lime. Leaching experiments showed that As was more mobile in the lime-dosed tailings than in subsurface non-amended tailings, likely owing to desorption in alkaline pH conditions. By contrast, the mobility of Cd, Cu and Zn in the surface lime-amended tailings was reduced by at least two orders of magnitude compared with subsurface non-amended tailings. Evaluation of the applied rehabilitation strategy highlights the limits of a single chemical remediation approach to a polymetallic (including metalloids) waste with complex mineralogy and large seasonal fluctuations. Rehabilitation of metalliferous mine sites requires a complete understanding of all environmentally significant elements and their pathways into local receptors.     

室内受控条件下对虾养殖环境综合生物修复技术研究

本研究在室内受控条件下,在虾、贝、藻的多池内循环养殖的基础上,采用残饵污染控制技术减少残饵生成量,并针对对虾养殖中产生的主要目标污染物质及其存在形态,镶嵌以相应的生物修复技术,探讨了综合生物修复技术对对虾养殖生态系统自身污染的修复效果。研究结果表明:采用虾、贝、藻及生物滤池综合生物修复技术可有效降低养殖水体中的悬浮物、溶解无机碳和溶解有机碳的含量。残饵即时修复技术可显著减少残饵生成量,但梭鱼和沙蚕对沉积物的扰动作用对综合生物修复效果产生了一定的负面影响。综合生物修复技术中大型藻类对水体中溶解无机氮的修复能力略显不足,在实际修复过程中需充分考虑大型藻类固氮速率和系统内生物排氮速率的平衡关系,并确保能满足大型藻快速生长最佳的水层空间。单靠微生物滤池对水体中有机物的修复能力并不理想,需辅助增加泡沫分离等技术,提高系统对大分子胶体的去除能力。本研究为进一步构建现场对虾养殖环境的综合生物修复技术体系奠定了基础。     

凹凸棒石-双交联水凝胶微球钝化修复镉污染土壤研究

为研究凹凸棒石-双交联水凝胶微球(SA/PVA/ATP)对镉污染土壤钝化修复的效果,将SA/PVA/ATP添加到镉浓度为3.72 mg/kg的土壤中进行淹水培育,采用模拟酸雨、二乙烯三胺五乙酸(DTPA)和三乙醇胺(TEA)混合提取剂(DTPA提取剂)提取土壤有效态镉;采用欧共体标准局顺序提取方法(BCR)提取土壤中不同形态镉;讨论了SA/PVA/ATP添加量、土壤有效态镉和各形态镉的相关性;计算了钝化容量、修复效率和重金属风险评价指数,探究了SA/PVA/ATP对土壤镉的钝化机理。结果显示,随着SA/PVA/ATP的增加,DTPA提取剂和酸雨提取的有效态镉含量分别从1.72 mg/kg和0.024 mg/kg下降到0.66 mg/kg和0.004 4 mg/kg;土壤中的弱酸可提取态镉和可还原态镉含量分别从1.40 mg/kg和0.81 mg/kg下降到1.01 mg/kg和0.41 mg/kg,而可氧化态镉和残渣态镉含量分别从0.86 mg/kg和0.63 mg/kg增加到0.95 mg/kg和1.27 mg/kg。材料添加量与土壤中有效态镉、弱酸提取态镉和可还原态镉含量呈极显著负...     

新一轮土地整治规划分区研究——以山东省肥城市为例

进行土地整治分区是编制土地整治规划的重要内容之一。以往的土地整理复垦开发分区已不能适应当前土地整治工作管理的需要。该文以山东省肥城市为例,提出了土地整治分区的原则和方法,从宏观尺度上,运用聚类分析法进行土地整治综合分区,从中观尺度上,运用叠图法进行土地整治功能分区,并指出了不同区域土地整治的方向和重点。     

Study of polluted soil remediation based on freezing and thawing cycles

It is generally known that soil pollution poses a terrible hazard to the environment, but the present techniques of contaminated soil remediation cannot control this growing threat. This paper compares the pollutant extraction efficiency of traditional pumping and treating, which is a typical washing technology for the remediation of contaminated soils, with methods that utilize freeze-thaw cycles. In the soil freezing process, water shifts from unfrozen soils to the freezing front, and the permeability of soil will be enhanced under certain temperature gradients and water conditions. Therefore, this paper discusses the purification of contaminated soil through freeze-thaw action. We conducted a cleansing experiment on clay and silica sand infused with NaCl（simulation of heavy metals） and found that the efficiency of purification was enhanced remarkably in the latter by the freeze-thaw action. To assess the effective extraction of DNAPLs in soil, we conducted an experiment on suction by freezing, predicated on the different freezing points of moisture and pollutants. We found that the permeability coefficient was significantly increased by the freezing-thawing action, enabling the DNAPL contaminants to be extracted selectively and effectively.     

新型表面活性剂改性粘土去除赤潮藻研究

以赤潮异弯藻为主要研究对象,对其在有机高岭土和有机膨润土作用下的去除情况进行了研究。结果表明,以新型阳离子表面活性剂双烷基聚氧乙烯基三季铵盐改性后的粘土用量为0.03g/L时,在24h内对赤潮异弯藻的去除率可以达到100%,而未经改性的同样用量的粘土并没有对赤潮异弯藻表现出去除作用,这表明改性后的粘土对赤潮异弯藻的去除能力得到了显著的提高。同时还对改性粘土去除赤潮异弯藻的絮凝动力学及其对养殖生物日本对虾仔虾的生态毒性情况进行了研究,发现粘土的种类、用量,改性剂的用量及溶液的pH值等因素都能够影响体系的絮凝沉降速率,通过分析各种影响因素发现在粘土体系中引入有机改性剂是提高其除藻能力的主要因素。另外,毒性实验发现所用改性剂对养殖生物的毒性较小,半致死浓度约为61.9mg/L,比传统的季铵盐的毒性降低了50倍左右,是一种较为安全有效的粘土有机改性剂。     

土地整理三维信息系统研究与实现

为保证土地整治项目管理信息系统科学有效,本研究采用三维可视化技术构建交互式应用环境,开发出土地整理三维信息系统,应用于土地整治项目管理和国土资源管理,为土地综合整治及国土基础数据管理的信息化、可视化提供技术支撑和服务。