重金属对土壤的污染

<正> 我国土壤污染的现状 土壤污染大致可以分为:重金属污染、农药和有机物污染、放射性污染、病原菌污染等多种类型。 据报道,目前我国受镉、砷、铬、铅等重金属污染的耕地面积近2000万hm~2,约占总耕地面积的1/5;其中工业“三废”污染耕地1000万hm~2,污水灌溉的农田面积已达330多万hm~2。例如:某省曾对47个县和郊区的259万hm~2耕地(占全省耕地面积的2/5进行过调查。其结果表明,75％的县已受到不同程     

洞庭湖湿地周围表层土壤重金属污染及其人体健康风险评价

为了查明洞庭湖湿地周围表层土壤重金属污染及其对人体健康的风险,选择2016～2018年洞庭湖区域周围10个土壤采样点,共采集了表层土壤(0～30 m)样品100份,分析了其中的重金属含量、分布,并采用地累积指数法(I_geo)、内梅罗指数法(N_I)和土壤健康风险评价法等方法进行了风险评价。结果表明:土壤样品中Pb、Cd、Hg、As和Cu 5种重金属元素的平均浓度分别为53.33、1.62、0.27、26.8和37.72 mg/kg,高于研究区域土壤环境背景值。其中Cd、As的平均浓度,西洞庭湖、南洞庭湖和东洞庭湖Cd的浓度和南洞庭湖As的浓度均高于《土壤环境质量标准》(GB 15618—2018)中农用地土壤污染风险筛选值的标准。Cd、Hg、As和Cu的最大污染值在南洞庭湖,Pb的最大污染值在东洞庭湖。地累积指数法(I_geo)研究表明,三年时间里,Cd处于重度污染水平,Pb、Hg、As处于无污染到中度污染水平。内梅罗指数法(N_I)研究表明,三年时间里,西洞庭湖、南洞庭湖和东洞庭湖都处于轻度污染水平。运...     

土壤中重金属的污染与危害

<正> 土壤无机污染物中以重金属比较突出,主要是由于重金属不能为土壤微生物所分解,而易于积累,转化为毒性更大的甲基化合物,甚至有的通过食物链以有害浓度在人体内蓄积,严重危害人体健康。 土壤重金属污染物主要有汞、镉、铅、铜、铬、砷、镍、铁、锰、锌等,砷虽不属于重金属,但因其行为与来源以及危害都与重金属相似,故通常列入重金属类进行讨论。就对植物的需要而言,可分为两类:一类是植物生长发育不需要的元素,而对人体健康危害比较明显,如Ca、Hg、Pb等;另一类是植物正常生长发育所需     

植物如何清除土壤重金属污染

<正>英国《自然》周刊刊登的一项研究称,一种生长在被重金属污染的土地上的植物使科学家们找到了复育污染土地的秘决。     

南京部分郊区土壤被重金属污染已不宜种菜

正2012年5月18日现代快报报导:"现在,农田土壤污染加剧,工业场地和矿区土壤污染更加突出,我们现在提出来要把一些在城市里面的工业企业退出主城区,迁往工业园区,这个叫退城进园,退二进三,现在很多城市都在进行。"作为土壤专家,赵其国院士对目前严峻的土壤污染深感担忧,要谨防土壤中的重金属污染通过食物链、居住环境进入人体,危害人们的健康。     

云南某典型锡矿选矿厂重金属污染特征

选择云南某典型锡选矿厂为研究对象,根据产污节点设置废水、粉尘、固体废弃物的采样点,通过取样、测试分析研究不同节点的重金属污染特征,应用单因子指数法和内梅罗综合污染指数法评价其污染状况,并对重金属总量进行对比分析。结果表明:锡选矿行业产生的废水以及粉尘中的重金属元素含量明显高于其参比值,尾矿中Zn、As、Cu、Pb含量较高,平均含量分别为2225、1855、870.50、417 mg/kg,尾矿库周边表土重金属含量明显超过背景值并和尾矿中重金属污染情况基本一致。单因子指数法评价结果显示,废水中重金属污染程度由高到低依次为Zn、Pb、As、Hg、Cu(Cd、Cr6+、Sn未检出),粉尘中重金属污染程度由大到小依次为As、Cd、Cu、Zn、Pb、Hg、Cr(Sn缺乏参比值),尾矿库周边表土重金属污染程度由大到小依次为Zn、As、Pb、Cu、Cr、Sn、Cd、Hg。内梅罗综合指数法结果表明:精矿过滤设备和粉矿仓这两个节点的重金属污染能力最高,而尾矿库周边土壤综合污染指数达到21.73,远远超过5级评价指标。重金属总量对比分析发现,研究矿区已经形成多种重金属复合污染的特征,其中重金属产生绝对量由大到小依次为Zn、As、Cu、Pb、Sn、Cr、Cd、Hg,且尾矿重金属产生量所占比例最高,达到79.17%。     

某铅锌矿区土壤重金属形态分布及污染风险评价

对某铅锌矿区土壤的铅、镉、锌、铜和镍的污染特征进行了研究。结果表明,5种重金属的污染程度依次为：镉〉铅〉锌〉镍〉铜,其中铅、镉和锌的浓度超过了国家土壤环境质量标准Ⅲ的浓度限值。土壤受镉污染极大,受锌污染中度至严重,受铅污染严重至极严重。BCR顺序提取形态分析结果表明,活性镉、铅和锌的含量较高,可能对土壤中的植物生长产生不利影响,而铜和镍以相对稳定的形式存在。潜在生态危害结果表明,镉污染导致土壤潜在着极大的生态风险,应当引起重视。     

土壤中重金属的污染与危害

污染土壤的无机物中以重金属比较突出,主要是由于重金属不能为土壤微生物所分解,而易于积累,转化为毒性更大的甲基化合物,甚至有的通过食物链在人体内蓄积,严重危害人体健康.     

重金属污染危害不容小视

重金属污染与其他污染物相比,有其独特性。一是具有毒害性,可以引起中毒、致癌等：二是具有欺骗性,多数重金属废水是无色透明的,不了解的人会把重金属废水当做清洁水,有的农民直接用于灌溉,有的牲畜直接饮用;三是具有富集性,重金属能通过食物链成倍富集,最后进入人体;四是在治理上具有长期性,水体和土壤一旦被重金属污染,治理难度很大,周期很长。     

重金属污染不容忽视

重金属污染不仅仅使人民的健康受到危害,我们长期赖以生存的绿色家园也难逃魔爪,当百姓健康受到严重影响时,谁该为环境污染“负责”？     

兰州市永登县红城镇耕地土壤污染现状评价

为了解耕地土壤的污染状况,本文以兰州市永登县红城镇主要耕地区域为研究对象,通过布设1条垂直剖面的手段,并采集了13件表层土壤样品、2件深层土壤样品、1件灌溉水及1件灌溉渠底泥样品,进行了化验分析对比试验.文章认为研究区灌溉水环境质量好,灌溉渠底泥清洁,表层土壤砷、镉、汞、锌存在一定累积性,但总体上土壤环境清洁.     

有机酸对污染土壤中重金属释放或固定的影响

为了探明土壤中不同有机酸对土壤中重金属环境活性的影响,通过采用分批次实验分别研究高分子有机酸(HMWOA)(腐殖酸和富里酸)和低分子有机酸(LMWOA)(苏氨酸和草酸)对土壤中Pb、Cu和Cd释放或固定化效果的影响.结果表明,LMWOA特别是苏氨酸促进土壤中Pb、Cu和Cd的释放,并减少土壤中HOAc可提取态、可还原态...     

Acid mine drainage and heavy metal contamination in groundwater of metal sulfide mine at arid territory (BS mine, Western Australia)

The issues of acid mine drainage (AMD) and heavy metals contamination in the metal sulfide mine in the arid district were explored, through studying the acidification and the heavy metals distribution and evolution of groundwater in the black swan (BS) nickel sulfide mine (Western Australia). The groundwater samples were collected from the drilling holes situated in the vicinity of tailings storage facility (TSF) and in the background of the mine (away from TSF), respectively, and the pH and electric conductivity (E_c) were measured in site and the metal contents were analysed by ICP-MS and ICP-AES, quarterly in one hydrological year. The results disclose that the TSF groundwater is remarkably acidified (pH_mean≈5, pH_min=3), and the average contents of heavy metals (Co, Cu, Zn, Cd) and Al, Mn are of 1–2 orders of magnitude higher in TSF groundwater than in background groundwater. It may be due to the percolation of tailings waste water from mill process, which leads the tailings to oxidize and the deep groundwater to acidify and contaminate with heavy metals. Besides, the heavy metals concentration in groundwater may be controlled by pH mainly.     

重金属污染土防渗注浆材料的力学性能

采用水泥基复合注浆材料对有色金属矿区重金属污染土进行防渗隔离处理。水泥、粉煤灰和矿渣等主要材料分别以不同组分与水玻璃混合形成3种复合注浆材料。采用倒杯法试验、无侧限抗压强度试验等方法研究不同水玻璃掺量、波美度以及粉煤灰和矿渣掺量对复合注浆材料凝胶时间和抗压强度等力学性能的影响规律。此外,采用XRD和SEM等测试方法,从材料的物相组成及微观结构方面进一步分析了复合注浆材料的力学特性。研究结果表明：凝胶时间随着水玻璃掺量和波美度的增大而延长;粉煤灰可以显著延长凝胶时间,但使用矿渣代替部分粉煤灰会使凝胶时间略有减少。当水玻璃掺量在20%以下时,复合注浆材料抗压强度随着水玻璃掺量的增加而增加,当水玻璃掺量超过20%,抗压强度显著降低;抗压强度随波美度的增加而增大;粉煤灰和矿渣可提高复合注浆材料的抗压强度。     

Heavy metals contamination characteristics in soil of different mining activity zones

Depending upon the polluted features of various mining activities in a typical nonferrous metal mine, the contaminated soil area was divided into four zones which were polluted by tailings, mine drainage, dust deposition in wind and spreading minerals during vehicle transportation, respectively. In each zone, soil samples were collected. Total 28 soil samples were dug and analyzed by ICP-AES and other relevant methods. The results indicate that the average contents of Zn, Pb, Cd, Cu and As in soils are 508.6, 384.8, 7.53, 356 and 44.6 mg/kg, respectively. But the contents of heavy metals in different zone have distinct differences. The proportion of oxidizing association with organic substance is small. Difference of the association of heavy metals is small in different polluted zones.     

金属热处理工艺产污系数研究与思考

节能环保是中国制造业转型升级的前提,制造业绿色化、节能化是制造业发展的重要标志。热处理作为主要的基础制造工艺技术之一,其绿色化、节能化水平反映了制造业整体发展情况,研究热处理工艺本身的产污特征具有积极意义。本研究基于“第二次全国污染源普查工业污染源产排污核算”项目工作成果,针对金属热处理工艺、工序,深入研究其污染产生特征及产污系数,积极为“二污普”产污总量核算提供考察依据。     

Evaluation of ecological risk and primary empirical research on heavy metals in polluted soil over Xiaoqinling gold mining region,Shaanxi,China

Soil, crop and residents' hair over Xiaoqinling gold mining region, China, which was selected as a case study, were sampled and analyzed for Hg, Cd, Pb, Cu, Cr, As and Zn concentrations. The concentrations of heavy metals in soil or crop and hair samples were used to assess their potential ecological risks, or to find the responses to these metals as evidences to prove the potential risk was coming down to observed harm, respectively. The results showed that, these metals in soil were ranked by severity of ecological risk as Hg＞Cd＞Pb＞Cu＞Cr＞As＞Zn, based on their single-element indexes. In the view of the potential ecological risk indexes, of all soil samples, about half had significantly high or high potential ecological risk, which covered more than 74% of the studied region. Most of the risks were 97.41% from Hg, Pb and Cd, especially, 84.37% from Hg. Both the single-element and potential ecological risk indexes indicated that, the ecological risk grades had a special spatial characteristic, and increased from northwest to southeast generally. This was agreed with the spatial distribution of the strength in gold mining activities over the studied region. The concentrations of Hg and Pb were higher than their relative backgrounds in the corps, and were even 9.48 and 25.09 times higher than their relative backgrounds in residents' hair, respectively. All these showed that the heavy metals in the soil had a high potential ecological risk, especially, had been affecting these crops' growing and yield, and even the residents' health through food strains. Obviously, these metals' potential ecological harm had been coming down to observed harm to the ecology.     

Effect of sulfate erosion on strength and leaching characteristic of stabilized heavy metal contaminated red clay

Solidification/stabilization (S/S) technology has been widely used for remediation of the heavy metal contaminated soils. The heavy metal ions will be leached from the stabilized contaminated soil under sulfate erosion conditions, which gives rise to secondary contamination to the areas around the mine sites. The commonly used Portland cement, fly ash and quicklime were taken as binder raw materials with various mix proportions. And then, the sulphuric acid and nitric acid method was used to investigate the leaching characteristic of stabilized heavy metal contaminated soils. The effects of binder types and binder contents, sulfate concentrations (1.5, 3.0 and 6.0 g/L) and erosion time (0, 7, 14 and 28 d) on leached concentrations of heavy metal ions from contaminated soils were studied. Moreover, a parameter named immobilization percentage (IP) was introduced to evaluate the influence of erosion time and sulfate concentration on immobilization effectiveness for heavy metal ions. The results showed that, the leached heavy metal concentrations increased with sulfate concentration and erosion time. Comparatively speaking, the composite binders that had calcium oxide in it exhibited the worst solidification effectiveness and the lowest immobilization percentage, with the largest leached heavy metal concentration.