Leaching Effect of Organic Acids on Heavy Metal Contaminated Soil

With the contamination of soil heavy metals becoming more and more serious,remediation has become a hot issue,and it is of great significance to study the remediation effects of heavy metal contaminated soil. The heavy metal contaminated soil was leached with water,acetic acid and citric acid,and the pH value of the soil after leaching was adjusted with 2% lime water. Finally,the pH value and conductivity of the soil leacheate were determined. The results showed that the best leacheate was citric acid for the remediation of soil contaminated with heavy metals Cu,Cd and Pb,and the optimum leaching concentration was 1. 0,0. 4,0. 7 mol/L,respectively. For the remediation of soil contaminated with Zn,the best leacheate was acetic acid,and the optimal leaching concentration was 1 mol/L. The leaching effect of lime water on heavy metal contaminated soil was positively correlated with the concentration of organic acid,that is,the leaching effect on heavy metals was better at stronger acidic condition. The conductivity of the soil sample treated with lime water increased with the increase of the concentration of organic acid,and at the same concentration,the conductivity was in the order of citric acid > acetic acid.

Assessment and mapping of environmental quality in agricultural soils of Zhejiang Province, China

Heavy metal concentrations in agricultural soils of Zhejiang Province were monitored to indicate the status of heavy metal contamination and assess environmental quality of agricultural soils. A total of 908 soil samples were collected from 38 counties in Zbejiang Province and eight heavy metal （Cd, Cr, Pb, Hg, Cu, Zn, Ni and As） concentrations had been evaluated in agricultural soil. It was found 775 samples were unpolluted and 133 samples were slightly polluted and more respectively, that is approximately 14.65% agricultural soil samples had the heavy metal concentration above the threshold level in this province by means of Nemerow＇s synthetical pollution index method according to the second grade of Standards for Soil Environmental Quality of China （GB15618- 1995）. Contamination of Cd was the highest, followed by Ni, As and Zn were lower correspondingly. Moreover, Inverse Distance Weighted （IDW） interpolation method was used to make an assessment map of soil environmental quality based on the Nemerow＇s pollution index and the soil environmental quality was categorized into five grades. Moreover, ten indices were calculated as input parameters for principal component analysis （PCA） and the principal components （PCs） were created to compare environmental quality of different soils and regions. The results revealed that environmental quality of tea soils was better than that of paddy soils, vegetable soils and fruit soils. This study indicated that GIS combined with multivariate statistical approaches proved to be effective and powerful tool in the mapping of soil contamination distribution and the assessment of soil environmental quality on provincial scale, which is beneficial to environmental protection and management decision-making by local government.

Analysis of Heavy Metal Sources for Vegetable Soils from Shandong Province, China

Heavy metal pollution in agricultural soils has serious negative influence on human health. Concentrations of Cd, Hg, As, Pb, Cr, Cu, Zn, and Ni in top soils （0-20 cm） of greenhouses and farmlands from four main vegetable production areas Shouguang, Laiyang, Jinxiang, and Zhangqiu in Shandong Province, one of the most rapidly developing regions in China, were measured in this study. Shouguang is mainly occupied by greenhouse vegetables and the other three areas are mainly open field culture. Total of 149 soil samples were collected. The average concentrations of the eight heavy metals of the tested 149 soil samples were all below the threshold values according to ＂Farmland environmental quality evaluation standards for edible agricultural products （HJ332-2006）＂ of China. However, most of the studied heavy metals were present at higher concentrations than those of the natural background levels in local agricultural soils. Among the total 149 soil samples, 22 samples were contaminated by Cd, Ni, Cu, or Hg. Comparisons showed that the main pollution element in greenhouse vegetable soils was Cd, while that of open field vegetable soils was Cu. The results of principal components analysis （PCA） suggested that concentrations of Cr, As, and Ni were mainly controlled by parent rocks; Hg and Pb were affected by anthropogenic activities such as vehicle and industrial fumes and waste water irrigation. Meanwhile, concentrations of Cd, Cu, and Zn were affected mainly by the use of agrochemicals. Most of the heavy metals were positively correlated with each other in concentration. Appropriate measures should be taken to effectively control heavy metal levels in vegetable soils and thus protect human health.

Heavy metal accumulation in the above-ground vegetation and soil around an iron smelting factory in Ile-Ife, southwestern Nigeria

This study investigated the accumulation of heavy metals in the above-ground vegetation and soil around an iron smelting factory located at the Fashina Area, Ile-Ife, Osun State, southwestern Nigeria. This was with a view to establish baseline data which can be used for assessing the impact of the steel processing industry in the area. Samples of the two most common herbaceous species （Chromolaena odorata and Aspilia africana） around the factory were randomly collected at 10 m away from the wall of the factory, and soil samples were randomly collected at 0-15 cm depths in the same area. The plant species were oven-dried, put through a mixed acid digestion procedure, and, along with soil samples, were analyzed for N, P, K, C, Zn, Pb, Cd, Ni, and Cr using an atomic absorption spectrophotometer. The data obtained were subjected to appropriate descriptive and inferential statistical analyses. The results revealed that the soils were slightly acidic, with pH values of 6.23±0.24 in the dry season and 6.10±0.16 in the rainy season. There was a significant difference （P 〈0.05） in the percentage content of total N, total P, K, and organic matter values in the soil samples collected in the two seasons. The Cd, Pb, and Cr contents in the soil samples from the rainy season were significantly higher （P 〈0.05） than those of the dry season. The analyzed plant species showed a progressive decrease in the concentration of the elements tested, with percentage content of C 〉 P 〉 N in both Aspilia africana and Chromolaena odorata. In the dry season, C percentage concentration was higher in Aspilia africana, while the other elements followed the trend observed in the rainy season. The concentration of Zn was higher in Aspilia af- ricana in both the polluted site and the control site in the rainy season, while the concentrations of the other heavy metals were higher in Chromolaena odorata in the dry season. This study revealed that the heavy metal concentration varied with the plant species and also with the prevailing seasonal conditions. Also, the accumulation and concentration of heavy metals in both plant species and in the soil indicated a potential hazard of the factory to the local environment.

Source analysis and risk evaluation of heavy metal in the river sediment of polymetallic mining area:Taking the Tonglüshan skarn type Cu-Fe-Au deposit as an example,Hubei section of the Yangtze River Basin,China

In this paper,25 sampling points of overlying deposits in Tonglushan mining area,Daye City,Hubei Province,China were tested for heavy metal content to explore pollution characteristics,pollution sources and ecological risks of heavy metals in sediments.A geo-accumulation index method was used to evaluate the degree of heavy metal pollution in the sediment.The mean sediment quality guideline quotient was used for evaluating the ecological risk level of heavy metal in the sediment.And a method of correlation analysis,clustering analysis,and principal component analysis was used for preliminary analysis on the source of heavy metal in the sediment.It was indicated that there was extremely heavy metal pollution in the sediment,among which Cd was extremely polluted,Cu strongly contaminated,Zn,As,and Hg moderately contaminated,and Pb,Cr,and Ni were slightly contaminated.It was also indicated by the mean sediment quality guideline-quotient result that there was a high ecological risk of heavy metals in the sediment,and 64%of the sample sites had extremely high hidden biotoxic effects.For distribution,the contamination of branches was worse than that of the main channel of Daye Dagang,and the deposition of each heavy metal was mainly influenced by the distance from this sample site to the sewage draining exit of a tailings pond.The source analysis showed that the heavy metals in the sediment come from pollution discharging of mining and beneficiation companies,tailings ponds,smelting companies,and transport vehicles.In the study area,due to the influence of heavy metal discharging from these sources,the ecotoxicity of heavy metals in the sediment was extremely high,and Cd was the most toxic pollutant.The research figured out the key restoration area and elements for ecological restoration in the sediment of the Tonglüshan mining area,which could be referenced by monitoring and governance of heavy metal pollution in the sediment of the polymetallic mining area.

Sources, distribution, behavior, and detection techniques of microplastics in soil: A review

In recent years, the problem of environmental pollution caused by microplastics has attracted widespread attention. This paper reviews the latest research progress in terms of the source, content and distribution characteristics, harm, and detection technology of soil microplastics by referring to the relevant literature on soil microplastics worldwide. It concludes that:(1) Existing studies worldwide have detected the presence of microplastics in soil, water, and atmosphere, and the use of agricultural films, sewage sludge,and other man-made activities are the main sources of microplastics in soil;(2) microplastics can adsorb heavy metals, persistent organic pollutants and antibiotics in soil, change the physical and chemical properties of soil. This will result in composite pollution and harm to the ecosystem;(3) microplastics in soil not only can destroy the activity of key soil microorganisms, but also enter the body of crops and soil animals, affecting normal growth of crops and soil animals, and further threaten human health;(4) at present, there is no unified operating standard for the sampling, processing, and detection process of microplastics. Analysis methods such as visual inspection, spectroscopy, and thermal analysis have both advantages and disadvantages, and emerging detection technologies require urgent development.Microplastics have become a new pollutant in soil and their distribution characteristics are closely related to human activities. They pollute the environment and threaten human health through the food chain.Although related research on soil microplastics has just begun, it will become the focus of research in the future.

土壤环境基准的科学问题与研究方法:以Cd为例

土壤环境基准是土壤环境质量标准制定的科学依据和基础。环境基准是土壤环境保护研究的前沿领域,涉及土壤环境化学、环境毒理学、生物学和风险评估等多学科交叉与基础性科学问题,了解和解决其所涉及的这些科学问题,是土壤环境基准研究的前提。本文针对土壤环境基准研究中影响重金属毒性阈值的非生物因子、生物因子、剂量效应关系测定中等几个关键科学问题进行了阐述,包括土壤老化因子与淋洗因子的矫正,低剂量刺激效应拟合及毒性数据归一化方法等,最后以农田土壤Cd为例,推导出不同性质土壤中Cd环境基准(HC_(5))及其与土壤性质的连续性分布曲线方程(LogHC_(5)=0.132pH+0.083OC+0.008CEC-1.448),以期为农田土壤环境指标基准的研究提供参考与借鉴。

氧化钙活化过硫酸盐修复重金属-有机物复合污染土壤

采用氧化钙活化过硫酸盐氧化法修复重金属-有机物复合污染土壤,考察了过硫酸钠投加量、过硫酸钠与氧化钙投加比、水土比等对修复效果的影响,探讨了机理。结果表明,在过硫酸钠投加量2.5 mmol/g,氧化钙与过硫酸钠投加比2∶5,水土比3∶1的条件下,汞、砷的钝化率分别为81%和83%,存在形态由弱酸提取态转化为更为稳定的残渣态,氯仿、苯、总石油烃和1,2,3-三氯丙烷的去除率分别为99%,98%,82%,80%。氧化钙一方面,催化过硫酸盐,产生硫酸根自由基和羟基自由基氧化重金属、降解有机污染物。另一方面,通过物理固封和吸附、络合、沉淀作用钝化汞、砷。研究为重金属-有机物复合污染土壤修复技术的实际应用奠定基础。

纳米零价铁复合材料对污染土壤修复的最新进展

土壤污染严重威胁农产品的安全和人类健康。近几年来纳米零价铁(nZVI)复合材料由于环境友好、易于制备、价格低廉、优异化学活性等特点广泛地应用于污染土壤修复,但是对土壤中不同污染类型修复的调研较少。综述主要调研nZVI复合材料修复污染土壤中重金属、有机污染物和石油有机物的最新进展。重点评述nZVI复合材料的不同性质对污染土壤中各种污染物修复效果的影响,最后对n ZVI铁复合材料修复污染土壤得出结论并对未来方向进行展望。该综述为更好地应用nZVI复合材料对污染土壤的修复提供理论依据和指导。

生物炭吸附性能的影响因素及其在土壤中的应用

生物炭是通过高温热解处理制得的一种固体炭质材料,主要由碳元素组成,具有坚固、稳定和高孔隙度的特点。目前,生物炭可应用于水体中重金属和有机污染物的治理,以及土壤pH调节、土壤改良、碳封存、污染治理和农业生产增效等方面。本文综述了影响生物炭吸附性能的因素,以及生物炭在土壤中的应用,并对其在土壤中更加合理的应用做出展望。影响生物炭吸附性能的主要因素包括原料种类、热解温度、热解时间、pH、使用剂量和改性方法等。生物炭在土壤中的应用主要包括改善土壤理化性质、吸附土壤中重金属和有机物污染物、提供营养元素和促进植株生长等。

凤垟乡稻田土壤重金属污染评价及其来源

以泰顺县凤垟乡稻田土壤为研究对象,采集了6个种植区域站位点的土壤,通过电感耦合等离子质谱仪法测定了土壤中Cu、Pb、Cd、Zn、Cr和Ni含量,并采用单因子污染指数、内梅罗综合污染指数和地累积指数法对研究区域稻田土壤的污染程度进行了分析。结果表明:稻田土壤中Cu、Pb、Cd、Zn、Cr和Ni的平均含量分别为11.35、26.75、0.29、57.92、23.92、14.35 mg·kg^(-1)。通过单因子污染指数、内梅罗综合污染指数和地累积指数法评价后,表明6个站位点均为无污染状态。通过与农用地土壤风险筛选值比对,所调查的稻田土壤重金属含量均值均小于对应的农用地土壤风险筛选值。

生物炭在土壤重金属和有机物污染修复中的应用研究进展

土壤中重金属和有机物污染既造成巨大经济损失,又严重威胁人类健康。生物炭作为来源广泛、制备简单,比表面积大、表面官能团丰富、孔隙结构发达的材料,被广泛应用于农业、生态修复和环境保护领域。从生物炭的来源与制备工艺、对污染物的吸附机理、影响因素以及在土壤重金属和有机物污染修复中的应用现状等方面进行了综述,同时对生物炭材料在土壤污染修复中的研究重点进行了展望,为生物炭在土壤污染修复中的应用提供参考。

土壤中重金属形态及有机物组分的电化学-质谱分析

本研究建立了一种电化学-质谱(EC-MS)法高通量分析土壤样品中的金属组分和有机物。首先,根据理化性质,将土壤样品中的金属组分和有机物组分分为水溶态、脂溶态、难溶态和可氧化态等4种形态;然后,分别采用萃取、反应、电解等方式对4种形态组分进行在线顺次提取;将提取后的组分在线传输至电喷雾电离源进行离子化,随后进行正、负离子模式检测。实际样品分析结果表明,该方法成功检测出土壤样品中多种水溶态金属盐和有机物(如Mg、Cr、Ni、Zn、Co、Cu、Al、Pb等多种水溶性金属盐,尿素及多种有机胺)、20多种脂溶态有机羧酸、以及难溶态金属盐(Mg、Ni、Cr、Pb、Co)和可氧化态(Cu、Pb)。该方法可为环境评估和环境治理提供技术支持。

土壤改进剂在重金属污染修复中的应用研究进展

自然和人为活动排放到环境中的重金属可能对人类健康、生态环境、经济和社会发展产生有害影响,因此重金属污染土壤的修复近年来备受关注。在重金属污染土壤的几种修复技术(物理修复、化学修复和生物修复)中,利用土壤改进剂的金属稳定技术受到了相当大的关注,是一种很有前景的土壤化学修复方法。文章综述了近年来国内外土壤改进剂在修复重金属污染土壤方面的研究进展,包括黏土矿物、含磷材料、金属和金属氧化物等无机材料,有机质、城市固体废物和生物炭等有机材料,以及一些有机、无机材料联合施用在重金属污染土壤修复中的应用。这些改进剂通过吸附、络合、沉淀和氧化还原等多种修复过程,有效地降低了土壤中重金属的生物有效性。最后,文章展望了今后的研究方向:应继续加强改进剂的基础理论研究,明确化学稳定过程和重金属修复机制,以促进该领域的发展,为重金属在污染土壤中的稳定修复研究和实践提供有价值的参考。

不同生物有机肥对镉污染农田中水稻产量和土壤肥力的影响

[目的]探讨生物有机肥在镉(Cd)污染农田中的修复效果,保障水稻的安全生产。[方法]选用牛粪生物有机肥、炭基生物有机肥、大豆生物有机肥和海藻生物有机肥,在镉轻度污染稻田中开展为期2年的田间试验,测定土壤理化性质、土壤有效态Cd、水稻生长状况和产量、糙米Cd含量。[结果]田间试验结果表明生物有机肥的施用土壤pH平均提高0.32,碱解氮、有效磷、速效钾和有机质分别平均提高9.38%、15.69%、10.62%、11.64%。水稻株高、穗长、根长、穗重、千粒重和产量分别提高5.86%、3.83%、16.54%、16.91%、7.14%、3.65%。土壤有效态Cd含量显著下降0.10 mg/kg,降幅为39.12%,糙米Cd含量显著下降45.36%。[结论]生物有机肥在降低土壤Cd生物有效性和水稻籽粒中Cd含量具有显著作用,同时能够促进水稻生长和提高土壤肥力,其中炭基生物有机肥作用效果最好,未来可作为保障水稻安全生产的一项技术措施。

光谱分析土壤环境重金属污染监测研究

研究基于光谱分析的土壤环境重金属污染监测方法,解决土壤环境中重金属污染监测困难的问题。利用对角线法采集土壤样本,对土壤样本进行风干等预处理,将预处理后的土壤样本放置在激光仪中获取光谱数据,通过边界值判定对光谱数据进行平滑降噪处理,建立回归线性定量分析模型,分析光谱特征,得到土壤环境重金属污染的监测结果。结果:通过基于光谱分析的土壤环境重金属污染监测对土壤样本进行监测,得到土壤中的重金属污染包括铁、锌、锰、镉、镍、汞、钴等,监测精度较高。

生物有机肥对土壤镉形态及玉米镉积累的影响

为探究生物有机肥治理镉污染土壤的可行性及对土壤重金属污染修复的效果,采集河南省淅川县2种镉污染土壤,分别设置6种施肥处理:CK(不施用任何物料)、NPK(常规施NPK肥)、NPK+0.5%OF(常规施肥+0.5%商品有机肥)、NPK+1%OF(NPK+1%商品有机肥)、NPK+0.5%BF(NPK+0.5%生物有机肥)和NPK+1%BF(NPK+1%生物有机肥),测定种植前后土壤全镉含量、土壤各化学形态镉、玉米植株根系及籽粒镉含量。结果显示,以添加1%生物有机肥的治理效果最佳,NPK+1%BF处理下2种土壤有效态镉含量相较于NPK+1%OF降幅分别为19.74%、7.09%;施用有机物料降低土壤弱酸提取态镉含量,提高残渣态镉含量,NPK+1.0%BF弱酸提取态镉含量相比CK下降11%、残渣态镉上升16%;施用有机物料各处理玉米植株根系、籽粒镉含量显著降低,以NPK+1.0%BF处理效果最佳,相比NPK处理,土壤Ⅰ的玉米根系、籽粒镉含量降幅达34.41%、31.59%。综上,在镉污染土壤中施用生物有机肥,可显著降低土壤有效态镉含量,促进土壤弱酸提取态镉向残渣态镉转化,降低镉危害;玉米根系及籽粒镉含量均显著下降,综合治理效果表现为生物有机肥优于商品有机肥。

土壤重金属污染的环境影响评价及管理分析

重金属污染产生于多个方面,例如矿山开采、工业化工生产等方面。虽然,这些领域为建筑、生活提供了各种便利与原料,是经济发展与科学进步的体现,但由此引发的生态环境问题已然成为社会各界广泛关注的焦点。尤其是土壤中的重金属对环境的破坏更为突出。在这一背景下,本文探讨了土壤重金属污染的来源与危害,研究土壤重金属污染的环境影响评价及管理,为保护生态环境、土壤污染的预测、治理和土地利用管理提供合理化的环境决策依据。

离子色谱技术在水环境检测中的应用思考

随着工业化和城市化进程的加快,水污染问题日益严峻,对人类健康和生态环境构成了巨大威胁,所以需要对水环境进行监测。离子色谱技术作为一种高效、灵敏的分析方法,在水环境质量监测中显示出不可替代的作用。本文综合探讨了离子色谱技术的基本原理,并深入分析了其在水环境检测中的广泛应用,如常规阴阳离子、有机污染物、重金属的检测等。同时,文章也详细讨论了离子色谱技术的优势。离子色谱技术在实际应用中也存在着一些挑战和问题,例如高昂的设备与耗材成本、部分离子的检测效果不理想以及样品前处理步骤的复杂性等。针对这些问题,本研究提出了一系列改进措施,旨在进一步提升离子色谱技术在水环境监测中的效能和准确性。