某电镀厂六价铬污染土壤还原稳定化试剂筛选与过程监测

针对目前国内进行六价铬污染土壤修复过程关键性控制参数相对缺乏,且中长期稳定性效果相对较差等问题.选取北方某电镀厂六价铬污染严重的表层土壤,使用5组还原试剂进行还原稳定化试验,同时通过在线ORP(氧化还原电位)测试仪在线监测和定期取样测试,探索不同还原剂的反应效率和最终效果.其中试剂4对六价铬的还原稳定化率最高,基本上均在99.5%以上,六价铬浓度最低可达到2.4 mg·kg~(-1);从反应速率来看试剂1和4反应速率最快.反应过程的ORP、pH值监测数据也出现较大的区别,其中第1组土壤样品整个过程中ORP始终处于-400 m V左右;第4组反应在30 h以后,由-200m V逐步升高并稳定在100 m V左右.从反应体系中的pH值变化情况来看,唯一使土壤pH保持在7左右的是试剂4.综合判断试剂4(多硫化钙和亚铁盐复配试剂)的综合还原效果最佳.以试剂4为基础进行单独放大试验,通过ORP和电导率两个关键参数的变化情况发现还原反应过程大概需要160 h,从而为后期实际土壤修复过程中控制还原土壤的养护条件和过程监控提供理论支撑.     

土壤重金属污染及其修复技术研究

土壤重金属污染物有汞、镉、铅、锌等,主要来源于交通运输、工业污染和农业污染。土壤重金属污染会导致农作物减产甚至死亡,对人体健康也会产生极大危害。目前土壤重金属污染修复的技术主要包括工程修复法、物理化学修复法、化学修复法和生物修复法。植物修复技术作为一种新兴的绿色、生态、高效的修复技术具有良好的发展前景。     

The Water Table: The Shifting Foundation of Life on Land

Hyperarid, arid, and semi-arid lands represent over a third of the Earth’s land surface, and are home to over 38 % of the increasing world population. Freshwater is a limiting resource on these lands, and withdrawal of groundwater substantially exceeds recharge. Withdrawals of groundwater for expanding agricultural and domestic use severely limit water availability for groundwater dependent ecosystems. We examine here, with emphasis on quantitative data, case histories of groundwater withdrawals at widely differing scales, on three continents, that range from the impact of a few wells, to the outcomes of total appropriation of flow in a major river system. The case histories provide a glimpse of the immense challenge of replacing groundwater resources once they are severely depleted, and put into sharp focus the question whether the magnitude of the current and future human, economic, and environmental consequences and costs of present practices of groundwater exploitation are adequately recognized.     

房地产用地土壤污染环境风险评价——以江苏某搬迁企业原址用地为例

许多房地产项目都是在工业企业原址上进行开发建设,可能存在不同程度的土壤污染。土壤污染的评估和修复方案已成为房地产开发项目环评的重点,文中采用单因子指数法、内梅罗指数法和土壤背景值对照法对江苏某房地产用地土壤进行了环境风险评价,结果表明该地块不需要进行土壤修复和处置。     

微波修复原油污染土壤的均匀设计实验

采用均匀设计实验方法,研究了微波修复原油污染土壤时原油去除率与微波能耗、含水率和含炭率等因素的关系,并应用MATLAB编程拟合出经验公式。结果分析表明:微波能耗在0～288 kJ范围内,污染土壤的原油去除率随微波能耗线性增加;在含水率为6%、含炭率为4%、微波能耗从0增加到288 kJ时,原油去除率从0%增加至92.3%;含炭率在0%～4%范围内原油去除率与含炭率成线性关系,在微波能耗为288 kJ、含水率为6%、含炭率从0%增加到4%时,原油去除率从12.3%增加至92.3%;原油去除率与含水率成二次曲线关系且开口向下,微波修复原油污染土壤的最佳含水率为6.6%。研究结果对微波修复原油污染土壤技术的优化提供了有价值的参考。     

结合《土壤污染防治行动计划》探讨中国土壤环境监管制度与标准值体系建设

2016年,中国国务院印发《土壤污染防治行动计划》(简称《土十条》),明确提出对农用地土壤实施分类管理,按照污染程度划分为优先保护类、安全利用类和严格管控类;对建设用地要防范新增污染,针对疑似污染地块,开展土壤环境状况调查评估,保障地块安全再利用;以影响农产品质量和人居环境安全的突出环境问题为重点,制定土壤污染治理与修复规划,组织开展治理与修复。实施严格的土壤环境质量保护、污染土壤的风险管控、高风险污染土壤的治理与修复是落实《土十条》的重要任务,也是建设我国土壤环境监管制度的重要内容。土壤环境标准是实施土壤环境管理的重要依据。本文基于《土十条》重要任务以及当前及今后一段时期国家土壤环境管理需求,以土壤环境管理需求为导向,探讨提出了包括土壤环境质量保护标准值、土壤环境风险管控标准值、污染土壤修复标准值的土壤环境标准值体系,可望为国家土壤环境标准体系的建立和标准制修订方法的发展提供技术参考。     

有机酸土柱淋洗法修复重金属污染土壤

通过室内模拟实验,采用土柱淋洗方法,研究草酸、柠檬酸、乙酸和酒石酸溶液对某电镀厂附近土壤中重金属的去除效果。探讨了淋洗剂浓度、淋洗次数和淋洗时间等对淋洗效果的影响,研究草酸淋洗前后土壤中重金属形态的变化。结果表明,淋洗过程中铬的去除效果明显滞后于铜、锌和镍3种重金属离子。1 mol/L的草酸在土水比为1∶1,淋洗5h,淋洗4次的条件下可以达到最佳淋洗效果,Cu、Zn、Ni和Cr的去除率分别是99.6%、66.98%、88.7%和18.23%。     

Nitrogen fertilizer improves boron phytoextraction by Brassica juncea grown in contaminated sediments and alleviates plant stress

In this study we evaluated the effect of different fertilizer treatments on Brassica plants grown on boron-contaminated sediments. Experiments were conducted in the laboratory and on the lysimeter scale. At laboratory scale (microcosm), five different fertilizers were tested for a 35-d period. On the lysimeter scale, nitrogen fertilization was tested at three different doses and plants were allowed to grow until the end of the vegetative phase (70 d). Results showed that nitrogen application had effectively increased plant biomass production, while B uptake was not affected. Total B phytoextracted increased three-fold when the highest nitrogen dose was applied. Phytotoxicity on Brassica was evaluated by biochemical parameters. In plants grown in unfertilized B-contaminated sediments, the activity of antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX) and pyrogallol peroxidase (PPX) increased, whereas catalase (CAT) decreased with respect to control plants. Addition of N progressively mitigated the alteration of enzymatic activity, thus suggesting that N can aid in alleviating B-induced oxidative stress. SOD activity was restored to control levels just at the lowest N treatment, whereas the CAT inhibition was partially restored only at the highest one. N application also lowered the B-induced increase in APX and PPX activities. Increased glutathione reductase activity indicated the need to restore the oxidative balance of glutathione. Data also suggest a role of glutathione and phytochelatins in B defense mechanisms. Results suggest that the nitrogen fertilizer was effective in improving B phytoextraction by increasing Brassica biomass and by alleviating B-induced oxidative stress.     

表面活性剂修复重金属污染土壤的研究

本文探讨了3种常用表面活性剂,十二烷基苯磺酸钠(SDBS)、十二烷基硫酸钠(SDS)、聚山梨脂(Tween-80)对被重金属铬、镉污染了的土壤的修复洗脱作用,以及被污染土壤对3种表面活性剂的吸附作用。淋洗实验结果表明,3种表面活性剂对土壤中的铬、镉有明显去除效果,聚山梨脂(Tween-80)对污染土壤中铬和镉的去除率分别为61.2%和37.06%。实验表明,土壤对3种表面活性剂均有较强的吸附作用,这种吸附作用对土壤重金属的去除会产生不利的影响。     

Contamination by arsenic and other trace elements of tube-well water along the Mekong River in Lao PDR

Arsenic and other trace element concentrations were determined for tube-well water collected in the Lao PDR provinces of Attapeu, Bolikhamxai, Champasak, Savannakhet, Saravane, and Vientiane. Water samples, especially from floodplain areas of central and southern Laos, were significantly contaminated not only with As, but with B, Ba, Mn, U, and Fe as well. Total As concentrations ranged from <0.5 μg L⁻¹ to 278 μg L⁻¹, with over half exceeding the WHO guideline of 10 μg L⁻¹. 46% of samples, notably, were dominated by As(III). Samples from Vientiane, further north, were all acceptable except on pH, which was below drinking water limits. A principal component analysis found associations between general water characteristics, As, and other trace elements. Causes of elevated As concentrations in Lao tube wells were considered similar to those in other Mekong River countries, particularly Cambodia and Vietnam, where young alluvial aquifers give rise to reducing conditions.