粤北某矿下游农用地花生种植的重金属风险

对粤北矿尾矿库附近及下游酸性废水影响下的农用地种植的花生及其根部土壤和灌溉河水样品中4种重金属Cr、Cu、Pb、Zn进行分析研究,通过单因子污染评价法、生物富集系数法和THQ健康风险评价法,探讨4种重金属对灌溉河水、农用地土壤、种植花生的污染情况及健康风险程度。结果显示,研究区河水及根土中重金属污染程度以Cr最低,其次是Pb,最高为Cu、Zn,但种植花生的健康风险Cr却最高,Cu、Zn其次,Pb则最低。花生仁对Pb的富集不明显,但也具有一定的潜在健康风险。总体来说,该地区种植花生的重金属风险Cr、Cu、Zn偏高、Pb不明显,该结果可为该区域农用地的安全利用提供理论依据。     

2种固化剂对重金属和砷复合污染底泥的稳定化处理效果

通过底泥交换态重金属和砷含量的分析以及毒性浸出测试,考察磷酸氢二铵和碳酸钙对底泥中重金属和砷的稳定化处理效果。结果表明,随着磷酸氢二铵添加量的增加底泥pH值逐步降低,随着碳酸钙添加量的增加底泥pH值逐步升高。磷酸氢二铵对底泥中Pb的稳定有良好效果,然而对Zn、As却产生了极大的活化作用。碳酸钙对底泥中Pb、Cd、Zn的稳定有良好效果,但对As的稳定没有明显作用。相对而言,碳酸钙更适合用来稳定化处理重金属和砷复合污染底泥。     

某再生铅工业园周边土壤重金属的空间分布及来源分析

基于表层土壤重金属的实测含量,运用多元统计和地统计相结合的方法,对某再生铅工业园周边土壤重金属的分布情况和来源进行分析。结果表明,再生铅工业园周边土壤中Pb、Cd、As、Cr、Cu、Ni、Zn的几何平均含量分别为124.05、0.394、21.18、82.72、24.23、35.47、62.04 mg/kg。其中Pb、Cd、As分别是背景值的4.96、2.90、1.84倍,其余重金属元素含量与土壤背景值相当。重金属Pb、Cd在临近工业园区域含量较大,以工业园为中心呈岛状空间分布,且在工业园东部呈扩散趋势;As在周边农田中具有一定的累积量。来源分析表明,土壤中Pb、Cd主要受工业园生产活动的影响,而As则可能受到农业生产活动的影响。     

Reaction of sewage farm soils to different irrigation solutions in a column experiment 2. Heavy metals and their leaching

Heavy metal polluted soils from a recent and a former sewage farm were studied in a 2.5 years‐column experiment under various irrigation regimes and/or liming treatment. The copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd) concentrations in the soil and the leaching of these elements were studied. The amounts of the metals leached differed markedly between both soils, however, the effect of various irrigation treatments was less pronounced. The heavy metal content in the soil solid phase depended on the organic carbon content, however these dependencies differed for both soils as well as for particular metals. In lower soil horizons, the amount of heavy metals bound by unit mass of organic carbon was constant. It was assumed that the same amount of the heavy metals can be bound by the unit mass of the DOC. Under this assumption the amount of the DOC in the former sewage farm soil was in general too small to carry all heavy metals leached. Therefore leaching of their cationic forms has been postulated. The amount of the DOC in the present sewage farm soil could carry more heavy metals than these being leached. Therefore, an undersaturation of the DOC in heavy metals could occur in this soil.<?show $6#>     

生物淋滤去除农用污泥中重金属的效果及工艺

污水处理厂污泥中的重金属含量高是污泥农用的主要障碍。该文针对天津污水处理厂污泥含铜量高的特性,分别以硫酸亚铁和硫粉作为培养基进行生物淋滤对比试验,前者对铜的去除率远远高于后者。以硫酸亚铁作为培养基,研究了投配比、接种污泥量、pH值和温度对污泥中重金属去除效果的影响。结果表明,在硫酸亚铁投配比为10 g/L、污泥接种量为20%、温度为28℃、淋滤时间为4 d时,污泥中重金属Cu、Pb、Cr、Ni、Zn和Cd的去除率分别为89%、38%、61%、76%、72%和57%,其相应残余量分别为116、62.5、98、22、174、1.1 mg/kg。在7～28℃范围内,温度越高,氧化亚铁硫杆菌活性越高,生物淋滤时间越短;28℃和35℃下氧化亚铁硫杆菌活性基本相同。以硫酸亚铁为培养基淋滤处理后污泥中重金属的含量可满足《农用污泥中污染物控制标准》(GB4284-1984)。     

Heavy metal contamination of agricultural soils around a chromite mine in Vietnam

Abstract

In Vietnam, the Co Dinh mine is the largest chromite mine in the country. Mining, ore dressing and disposal of the tailings provide obvious sources of heavy metal contamination in the mine area. The present study examined the influence of chromite mining activities on the adjacent lowland paddy field by investigating heavy metal and As levels in the mine tailings, sediments, paddy soils and water. At paddy fields located near the mine tailings, the total contents of Cr, Co and Ni were 5,750, 375 and 5,590?mg?kg^?1, and the contents of their water-extractable form were 12.7, 1.16 and 32.3?mg?kg^?1, respectively. These results revealed severe contamination of lowland paddy soils with Cr, Co and Ni as a result of mining activity, suggesting serious health hazards through agricultural products, including livestock in this area. The principal source of the pollution was sediment inflow owing to the collapse of the dike, which was poorly constructed by heaping up soil. Moreover, water flowing out from the mining area was also polluted with Cr and Ni (15.0–41.0 and 20.0–135?μg?L^?1, respectively). This might raise another problem of heavy metal pollution of watercourses in the area, indicating the need for further investigation and monitoring of fluctuations of water quality with seasonal changes.     

Environmental impacts of surface mining on mined lands,affected streams and agricultural lands in the Dabaoshan Mine region,southern China

Impacts of surface mining on ecosystems were investigated in the Guangdong Dabaoshan Mine region, southern China. Significant soil acidification has been induced by mining activities which cause oxidation of metal sulfides contained in the mine spoils. Natural colonization of vegetation in the mine site has been impeded and this has resulted in severe soil erosion. Acid mine drainage from this mine site has caused the degradation of the downstream aquatic ecosystems. Mine water with pH< 3·5 has been continuously flowing into a first‐order tributary of the Beijiang River and has destroyed all the aquatic life to a distance of at least 25 km downstream of the discharge point, even when the pH rose to above 6 in the Hengshishui River (a third‐order tributary of the Beijiang River). Further downstream, macroinvertebrates first occurred at about 30 km from the discharge point, and only one species was found. This is in contrast to a reference site that was not affected by acid mine drainage, where 36 macroinvertebrate taxa were found. Acidic mine water also had marked impacts on the agricultural lands irrigated with it. Severe contamination of the soils by mine drainage is responsible for the extremely high concentrations of some heavy metals in the edible portions of a variety of food crops grown on the agricultural lands. Copyright © 2005 John Wiley & Sons, Ltd.     

煤矿区矸石山周边土壤重金属污染特征与规律

以山东某矿区为例,通过淋溶模拟实验,研究了煤矸石中重金属的淋溶规律,并探讨了煤矸石山周边土壤重金属污染特征.结果表明:风化矸石淋滤液中的Zn、Pb、Cr和Cu浓度较高,并很快稳定;新鲜矸石在淋溶初期检出Zn,其它重金属元素没有检出;风化矸石淋滤液中重金属的含量要高于未风化矸石.矸石山周边表层土壤中的Zn、pb、Cr和Cu较高,且浓度高出矸石淋溶液许多倍,表明煤矸石中重金属淋滤具有长期性,矿区土壤对重金属具有迁移性和富集性.表层土壤重金属含量随着距煤矸石堆的距离增加而呈明显的下降趋势,充分表明矸石山对周边土壤造成了严重的重金属污染,而且在土壤剖面上,重金属含量表现出随土壤深度的增加而降低的趋势.     

连续施用酸化粪水对土壤养分淋溶及重金属累积的影响

为探索连续施用酸化粪水对土壤养分淋溶及重金属累积情况的影响,采用新鲜粪水和酸化粪水,开展土柱淋溶试验。试验分别设置1个对照组、新鲜粪水和3个不同pH值（6.5、6.0和5.5）的酸化粪水,每个处理分别设置6次粪水淋溶。结果表明：施用新鲜粪水和酸化粪水均能增加土壤养分,施用新鲜粪水、pH值6.5、pH值6.0和pH值5.5的粪水后土壤总养分（N、P、K）的增长幅度分别为1%～40%、15%～66%和5%～21%,重金属Cu和Zn的增长幅度为4%～48%和4%～11%,重金属Cd和Pb的增长幅度为2%～14%和1%～18%;连续施用酸化粪水会使土壤pH降低、土壤电导率值升高以及土壤重金属不断累积,这也是导致土壤环境遭到破坏的风险因素,实际应用过程中应特别注意;建议每两季作物施用一次pH值为6.5的粪水;每三季作物施用一次pH值为6.0的粪水;每四季作物施用一次pH值为5.5的粪水。该研究通过对比分析连续施用新鲜粪水和不同pH值的酸化粪水后土壤养分和重金属浓度的变化,探讨了酸化粪水的还田效果,为连续施用酸化粪水的研究提供技术支撑。     

模拟酸雨条件下生物炭对污染林地土壤重金属淋失和有效性的影响

通过土柱淋溶装置,研究模拟酸雨条件下生物炭不同施用量(0,1%,2%和5%)对复合污染林地土壤重金属淋失和有效性的影响。结果表明,淋滤液pH值、电导率和溶解性有机碳含量均随生物炭施用量的增加而增加。生物炭施用不同程度地增加淋滤液中Cd、Cu和Zn的含量,相较于不施生物炭,1%,2%和5%生物炭施用量下Cd、Cu和Zn的累计淋失量分别提高28.3%~298.3%,25.3%~187.0%和27.5%~217.6%。不同处理间Pb的淋失总量无显著差异。生物炭的施用能使淋溶后土壤pH值提高0.03~0.09个单位,有效态Cd、Cu、Zn和Pb含量分别下降0.9%~6.5%,23.3%~30.6%,15.2%~24.2%和24.8%~31.8%。综合而言,酸雨作用下尽管生物炭能增加林地土壤中重金属的淋失量,但考虑到其淋失量远小于土壤中有效态重金属的减少量,生物炭仍可作为修复污染林地土壤的一种备选材料。     

农田土壤重金属淋洗剂筛选与效应分析

为分析不同淋洗剂在不同淋洗条件下对重金属淋洗效果的影响,采用振荡淋洗法对比研究4种淋洗剂(柠檬酸(CA)、酒石酸(TA)、乙二胺四乙酸二钠盐(EDTA)和氨三乙酸三钠盐(NTA))不同浓度、淋洗时间、pH和固液比对重金属复合污染农田土壤中Pb、Cd、Cu和Zn的淋洗效果及单因素最佳淋洗条件下土壤淋洗前后重金属不同形态含量的变化。结果表明,CA和TA的最佳淋洗浓度为0.3mol/L,EDTA和NTA为0.05mol/L;CA和NTA的最佳淋洗时间为480min,EDTA和TA为720min;4种淋洗剂的最佳淋洗pH均为3,最佳固液比均为1∶20。单因素最佳淋洗条件下,EDTA对土壤重金属去除效果最佳,对Pb、Cd、Zn和Cu的去除率分别为67.4%,61.0%,13.8%和76.0%;NTA效果次之,去除率分别为41.6%,42.4%,9.9%和54.3%。土壤重金属去除率随淋洗剂pH的降低而升高,随固液比的增加而增加,随淋洗剂CA与TA浓度增大而增大。淋洗剂对土壤重金属的解吸动力学曲线符合准二级动力学模型,解吸过程为化学解吸,且解吸反应速率受土壤重金属含量与淋洗剂浓度控制。土壤重金属在淋洗剂作用下的解吸速率为Cd>Pb≈Zn≈Cu。EDTA和NTA淋洗显著降低土壤中Pb、Cd、Zn和Cu铁锰氧化态和有机结合态的含量,CA和TA显著降低Pb、Cd、Zn和Cu铁锰氧化态的含量。淋洗剂对重金属的去除效率为EDTA>NTA>CA>TA。     

Control of geochemical mobility of arsenic by liming in materials subjected to acid mine drainage

Background  Acid mine drainage (AMD) results from the exposure of sulfide materials to atmospheric water and oxygen. In addition to AMD, oxidation of arsenopyrite and other As-bearing sulfides can release arsenic (As) into the environment. In view of the risk to living organisms due to contamination of ground and surface water sources with As, this work was carried out to evaluate the effectiveness of lime (CaCO₃) in controlling the dispersion of this metalloid in the environment. Methods  Partially oxidized samples of sulfide bearing materials from gold mines in Brazil were used to evaluate the arsenic mobilization by leaching tests. Columns containing ground samples, with and without liming treatments, were leached with distilled water every two weeks over a 156-day period. Results and Discussion  The acid-base accounting (ABA) static tests classified the samples as potential acid forming materials. In the treatments without liming, As, Fe and S concentrations in the leachates were higher than after treatment with carbonate. Nevertheless, the effectiveness of liming and As mobilization were lower in the sample containing goethite. A high correlation between Fe and As concentrations in the leachates (r=0.749) suggests that iron (hydr)oxides retained arsenic in the solid phase. Oxidation rates of As bearing sulfides were increased at low pH (2.0–3.9), probably due to the enhanced activity of bacteria (Acidithiobacillus) and decreased rate of Fe precipitation, thus reinforcing generation of acid water, and consequently releasing As. Conclusions and Perspectives  Our results corroborate the use of lime to control the dispersion of As in AMD-affected environments. However, the effectiveness of the liming treatment seems to be dependent on the presence of iron (hydr)oxides in the sample. These findings can be useful to remediate areas affected by acid mine drainage and arsenic mobilization in partially oxidized sulfide materials. ESS-Submission Editor: Chengrong Chen, PhD (c.chen@griffith.edu.au)     

北京城市流域底泥重金属形态特征及其生态风险评价

为了解北京城市流域底泥重金属污染现状及其生态风险,研究分别在北京市永定河流域、潮白河流域、温榆河流域、拒马河流域和泃河流域五大河系（北京段）共设置84个检测样点,采集底泥样品,利用ICP-MS分析法和BCR连续提取法测定北京城市流域底泥中铜（Cu）、锌（Zn）、铬（Cr）、镉（Cd）、镍（Ni）和砷（As）6种主要重金属的含量,分析其分布特征及养分变化,同时运用潜在生态危害指数法和地累积指数法综合评价流域底泥中重金属的生态风险。结果表明:（1）以北京土壤质量标准为北京市参比值,北京流域中下游底泥富营养化严重,重金属富集强弱依次为Cd > （Cr,As,Zn） > （Cu,Ni）;（2）底泥重金属潜在生态危害评价,其危害程度依次为Cd > （Cr,As,Zn） > （Cu,Ni）,其中五大河流下游潜在生态风险较大,生态风险最大的是拒马河水域;（3）地累积指数法进行污染评价,北京河流污染程度依次为下游 > 中游 > 下游,底泥中污染最大的重金属为Cd,其次为Cr,As和Zn,污染较小的为Cu和Ni。综上所述,北京污染较大的河流依次是拒马河、永定河、潮白河、温榆河和泃河,特别是河流下游区域底泥重金属累积较多,潜在生态危害最大。