Analysis and Assessment on the Heavy Metals in a Severely Degraded Subtropical Red Soil Region

5 different forests of Pinus massoniana, Schima superba, Liquidambar formosana, P. massoniana × S. superba, P. massoniana × L. formosana as the research object were set up to study the Cr, Cu and Zn content of degraded red soil region in subtropics. The soil heavy metal pollution degree was evaluated by national environmental quality standard (II class). The results showed that three soil metals of P. massoniana × S. superba were the highest, and the soil metals enrichment ability was strong. The order of single factor pollution index of metal elements was Cu (1.38) > Cr (0.81) > Zn (0.42), and moderately pollution, pollution warning and no pollution, respectively. There was no significant correlation between three soil heavy metals and soil total carbon (TC), total nitrogen (TN) and total phosphorus (TP). These results suggested that the accumulation of heavy metal elements was not derived from the parent material of soil. There was a significant positive correlation between the three metal elements which indicated that the sources of the three elements were similar. The structural equation model showed that the direct and indirect effects among the influencing factors ultimately affected the activity of heavy metals by cascade effects.

A land use-based spatial analysis method for human health risk assessment of heavy metals in soil and its application in Zhuzhou City, Hunan Province, China

A land use- and geographical information system-based framework was presented for potential human health risk analysis using soil sampling data obtained in Zhuzhou City, Hunan Province, China. The results show that heavy metal content in soil significantly differs among different land use types. In total, 8.3% of the study area has a hazard index(HI) above the threshold of 1.0. High HIs are recorded mainly for industrial areas. Arsenic((29)87%) and the soil ingestion pathway(about 76%) contribute most to the HI. The mean standardized error and root-mean-square standardized error data indicate that the land use-based simulation method provides more accurate estimates than the classic method, which applies only geostatistical analysis to entire study area and disregards land use information. The findings not only highlight the significance of industrial land use, arsenic and the soil ingestion exposure pathway, but also indicate that evaluating different land use-types can spatially identify areas of greater concern for human health and better identify health risks.

Characteristics of heavy metals in soils under different land use in a typical karst area, Southwest China

This study investigated the distribution of six pollutant elements(Cr, Cu, Pb, Zn, Cd, and As), and their relationship to soil organic carbon(SOC) in five soil profiles in the Puding area. Results show SOC content decreased exponentially to the depth of soil profiles; the vertical distribution patterns of SOC in soil profiles were partially controlled by land use. The concentrations of these pollutant elements in most soils were lower than background values, indicating that the local soil was less likely to be contaminated by foreign inputs. Geo-accumulation index values of these elements in most soil samples were less than 1, suggesting that the soil of this area may not be polluted. The concentrations of Cr, Cu, As, and Zn in soils from all land use types were significantly negatively correlated with SOC contents. Geochemical approaches confirmed that the soil of this area was less influenced by pollutant elements.

Effects of Land Use on Heavy Metal Accumulation in Soils and Sources Analysis

Heavy metal accumulation and its influential factors were studied in the different land use soils, which would provide a theoretical basis for controlling the content of heavy metals in soils. To identify the effects of land use on the accumulation of heavy metals in soils, 148 soil samples were collected from four land use patterns including greenhouse field, uncovered vegetable field, maize field, and forest field in Siping area of Jilin Province, China, and Cr, Ni, Cu, As, Cd, Pb, and Zn contents of those samples were determined with ICP and ICP-Mass. The result showed that there was a rather large difference in effects of the accumulation of Cr, Ni, Cu, As, Cd, and Zn in soils under different land use patterns, except Pb. Based on the assessment which compared with background concentrations in soil, the higher accumulation of heavy metals was found in greenhouse and uncovered vegetable field, much less in maize field and forest field. The mean contents of heavy metals in soils from high to low were arranged in order of greenhouse field, uncovered vegetable field, maize field, and forest field. Cd and Cu had relatively serious accumulation in soils compared to Cr, Ni, As, and Zn. The mean content of Cd in greenhouse field was 0.467 mg kg-x,which exceeded the grade II of the Chinese Soil Quality Criterion GB15618-1995 （6.5 〈pH〈7.5） for Cd standard of 0.3 mg kg^-1, while it was 5.2 times of Cd standard in the forest fields. The mean contents ofCr, Ni, Cu, As, Pb, and Zn in soils under four land use patterns were lower than the grade II of the Chinese Soil Quality Criterion. Compared with the soil cultivated years, the agricultural chemical compounds and manures application, especially the quality and quantity of applied fertilizer was one of the main reasons for leading to different accumulation of heavy metals in soils under the studied land use patterns. The accumulation of heavy metals, such as Cr, Ni, Cu, As, Cd, and Zn in soils was significantly affected by land use patterns, among them the accumulation of heavy metals in greenhouse soils was higher than others. It is suggested that the application of chemical fertilizer, organic fertilizer, and pesticides with high contents of heavy metals should be avoided to prevent the accumulation of heavy metal and keep high quality soils for sustainable use.

Heavy Metal Contamination of Surface Soil in Relationship to Land Use Patterns: A Case Study of Benue State, Nigeria

A detailed investigation was conducted on the relationship between land use patterns and trace metal content in surface soils of the Benue State to assess soil environmental quality. Results revealed that metals levels were generally high in mineralized and urban soils and lower in agricultural soils whilst forest soils were lease by anthropogenic pollution. Mineralized soils developed from weathered sulphides were rich in lead (Pb), zinc (Zn), and cadmium (Cd). Urban soils accumulated copper (Cu), Zn, and Cd most probably from refuse dumps, gasoline combustion and farming. Agricultural soils were enriched in arsenic (As) and to a lesser degree Pb and Cd originating most probably from the application of pesticides, manure and fertilizers. A pollution index (PI) based on plant-tolerant contamination levels, indicates that multi-element contamination in soils is low and implies that the sampled soils could be cultivated for crop production especially away from point sources of pollution. The degree of anthropogenic pollution was high for As (80%), and Pb (54%), moderate for Zn (47%), Cd (40%), and low for Cu (27%). Correlations (r) are significant between Zn- Pb (0.7), Cu-As (0.6) in mineralized soils, between Zn-Cu (0.64), Zn-Cd (0.5), Cu-Cd (0.6), in urban soils, As-Cd (0.61), in agricultural soils and Zn-Pb (0.82) in forest soils. These distinct relationships indicate a common source or similar geochemical control. Based on the overall evaluation, recommendation in respect of contamination, control and monitoring strategies as well as land use planning in the study area are presented.

Heavy Metal Fluxes in Tropical Urban Forest Soil in Abidjan District (Côte d’Ivoire)

In Western Africa, the growth of cities has led to natural resource pollution, especially air pollution. Urban forests play a key role in filtering atmospheric particles and pollutants through the canopy before reaching the soil. This study aims to quantify heavy metal fluxes in an urban forest in the district of Abidjan in order to assess its role in the protection of natural resources. A monitoring of wet deposition (throughfall and open field rain) and litterfall was carried out for six months in the urban forest of the National Floristic Center located in Abidjan, C?te d’Ivoire. The results show that the soil of this urban forest is a ferralsol type characterized by a sandy-clay texture and a low load of coarse elements. The annual litterfall is estimated to 12.16 ± 0.71 t·ha-1·yr-1, similar to other tropical forests. Annual quantities of rain and throughfall are in the range of the rainfall recorded in the district of Abidjan (2013 ± 152 and 1773 ± 51 mm). Chemical analyses showed that litter and rainfall contain Mn, Zn, Ni, Cr, Cd and Hg. Manganese and Zn are the most abundant elements and Hg the least abundant in both rainfall and litter. The main source of input of the heavy metals into the urban forest soil is associated with biological recycling through the litter. The litterfall contributes to metal fluxes in soil 109 times greater than metal fluxes carry by wet depositions (open field rain and throughfall). However, a detailed study of rainfall showed that the forest canopy constitutes a barrier for the transfer of heavy metal to urban soil. This is indicated by a decrease in heavy metal content from open field rain to throughfall. Consequently, this study recommends the creation and maintenance of urban forests to increase biomass canopy and improve atmospheric air quality for West African cities undergoing constant change and development.

Study on the proposed environmental guidelines for Cd, Hg, Pb and As in soil of China

This paper deals with the soil-environmental standard. According to the current situation of researching on the soil-environmental quality guideline at home and abroad, and on the basis of the foundations and principles of enacting the soil-environmental standard, the soil environment quality guideline values of Hg, Cd, Pb and As were suggested.

Implication of sewage sludge increased application rates on soil fertility and heavy metals contamination risk

This paper aims to assess soil fertility and risk contamination parameters in response to increased amendment rates of sewage sludge application,under semi-arid climatic conditions of Morocco,using two soil textures:soil A(clay-silty)and soil B(sandy-clay)over two years.To this end,sewage sludge and soils treatments physicochemical parameters,heavy metals content,degree of pollution and associated risks were evaluated and compared to controlled soils.The results showed that all studied parameters changed significantly(p<0.05)in a dose-dependent manner for both soils compared to the untreated control soils.Indeed,there were significant increase in organic matter(OM),total organic carbon(TOC)and nutrients content(N,P and K)of both sols as a response to increased sewage sludge amendment rates.Overall,sewage sludge application showed a positive agronomic potential for both soil and plant.However,there were concern about some heavy metals contamination risks,the results showed a gradual increase of heavy metals concentration in this order:Cu>Pb>Zn>Ni>Cd>Cr.Nevertheless,their concentrations were below the critical values established by the European Union for the agronomic use of soil.The obtained results of assessed parameters indicating SS degree of pollution and associated risks showed a low to a moderate contamination risks of heavy metals.Accordingly,environmental risks of sewage sludge application will be related to increase of heavy metals mainly in a long-term agricultural reuse.Thus,optimal management of sewage sludge application is recommended to ensure sustainability and benefits at the same time to master the contamination risks.

皖南典型区耕地土壤重金属富集特征、来源识别及健康风险评估

为探讨安徽省皖南山区典型耕地土壤重金属富集特征及成因,以安徽省东南部宁国市为研究对象,在耕地中采集1399件表层土壤样品,测定As、Cd、Hg、Pb、Cr、Ni、Cu、Zn元素含量,运用相关分析、土壤环境质量农用地土壤污染风险、地质累积指数、健康风险指数及PMF(正定矩阵因子分解)模型方法开展重金属风险评价及来源识别。结果显示:As、Cd、Hg、Pb、Cr、Ni、Cu、Zn含量的平均值分别为:15.8×10^(-6)、0.41×10^(-6)、0.106×10^(-6)、31×10^(-6)、67×10^(-6)、29.00×10^(-6)、29×10^(-6)、94×10^(-6),除Ni外,其他元素均高于安徽省背景值;重金属土壤污染风险水平整体较低,有866件土壤样品重金属含量低于风险筛选值;地质累积指数结果表明,耕地土壤主要受到Hg、Cd、As污染;健康风险评估结果显示,研究区内成人非致癌与致癌风险水平均在可接受范围内;基于PMF模型,确立了研究区重金属4种来源:与人类活动相关的工农业排放源、大气沉降源、与土壤类型相关的成土母质源和地质背景源。

Heavy metals contents in soil profiles of typical agricultural lands in Yixing,Jiangsu Province,China

The effect of land use pattern on the heavy metals(HMs)distribution in soil profiles was investigated in Yixing City,China,for the four typical types of land utilization,i.e.vegetable fields on the plain,paddy fields,tea gardens on hilly lands and bamboo groves.The variance of HMs concentration in the depth of 0-15 cm,15-30 cm,30-60 cm of soil profiles was compared among the different tillage ages. Results showed there was a notable accumulation of Cd,Hg,Cu,Pb,Zn and Cr in the soil profiles of vegetable fields and paddy fields causing a pollution of Cu,Hg and Cd in some profiles,while no remarkable accumulation of HMs in the soil profiles of the tea gardens and bamboo groves was found. The accumulation extent of HMs in the soil profiles of the four kinds of land use followed a sequence of vegetable fields>paddy fields>tea gardens>bamboo groves.The accumulation of HMs was mainly due to the industry,transportation,other urban human activities,and intensive use of fertilizers and pesticides.The downward leaching of HMs was relatively remarkable in the soil profiles of vegetable fields. There was an accumulation in surface and subsurface layers for Cd,Hg,Pb,Zn in the soil profiles of paddy fields and tea gardens,and for Cd,Hg in those of bamboo groves.Serious pollution effects of Hg, Pb,and Zn have been shown in the soil of vegetable fields.All the four kinds of agricultural land are basically free from the pollution of the external sources of As and Ni.With the increase of tillage time, the soil of vegetable and paddy fields will face the potential risk of HMs pollution,which mainly comes from Hg,Cd and Cu,whereas that of tea gardens and bamboo groves faces a relatively small risk.

我国农用地土壤重金属污染防治标准体系现状及展望

标准体系建设是实施土壤污染防治与农产品安全保障的重要保障.该文系统分析了我国农用地土壤环境质量管理发展历程,总结了土壤重金属污染控制标准体系的最新进展.在总结发达国家与国际组织关于农用地土壤重金属污染控制标准建设经验的基础上,分析我国标准体系当前所面临的问题及挑战,并提出本土化规划发展与完善建议,以期为我国农用地土壤重金属污染防范及风险阻控提供经验借鉴.该文将我国标准的建设历程大致总结为初识探索、质量管理、污染控制与风险管控4个阶段,初步形成了以法律、法规与国家政策为指导,国家、行业、地方与团体标准为基本框架,污染防治与农产品安全保障为总体原则的多维度、层次化、全链条污染防控标准体系.针对现行标准体系有待完善的内容,未来可通过应用导向与前瞻引领的顶层设计,强化农用地土壤重金属污染防治标准体系建设的科学规划和整体布局,满足适合我国不同阶段的农用地土壤环境管理需求,为深入打好净土保卫战提供理论基础和标准支撑.

土壤重金属污染钝化修复研究进展

如何有效治理和修复重金属污染土壤,保障粮食安全成为农业和环境生态领域的研究热点。在优质耕地资源短缺与粮食生产需求的突出矛盾背景下,原位钝化技术被认为是解决土壤重金属污染修复治理的切实可行,且能保证作物安全生产的修复措施。文章从钝化剂种类、钝化修复技术应用中存在的问题等方面综述了重金属污染土壤钝化修复研究的现状,分析了影响土壤重金属钝化修复效果的因素,并对未来重金属污染土壤的钝化修复研究思路提出了建议,以期为科学、合理、高效使用钝化剂和钝化修复技术提供理论指导,实现受污染耕地的安全利用。

北京市通州区绿地土壤重金属源解析及风险评价

【目的】北京市通州区土地利用类型变化较大,本研究对通州区绿地土壤开展重金属调查,进行源解析和风险评价,评判现阶段的绿地利用是否符合清洁安全的要求并提出重金属风险防控建议。【方法】采集并测定研究区60个表层土壤样品中的pH值及镉(Cd)、铬(Cr)、铅(Pb)、铜(Cu)、锌(Zn)、砷(As)和汞(Hg)等7种重金属全量。运用主成分分析法和绝对因子得分-多元线性回归(APCS-MLR)受体模型等方法进行源解析;采用地积累指数法、潜在生态风险评价法进行重金属污染评价。【结果】研究区土壤中Cd、Cr、Pb、Hg、As、Cu和Zn等7种重金属平均质量分数分别是0.53、47.87、11.95、0.25、6.71、4.64、51.21 mg·kg^(−1),所有点位的重金属质量分数均没有超过GB 15618—2018《农用地土壤污染风险管控标准》。主成分分析表明:Cd、Pb、Hg、As受人为源影响,主要来自煤炭燃烧、交通、工业和农业活动污染;Zn受自然源影响,和土壤母质有关;Cu和Cr受混合来源影响,来自土壤母质和农业活动污染。根据受体模型对重金属元素进行定量源解析,发现在表层有一定累积的Cd大部分来自人为源(92%);Hg分别来自工业源(29%)、燃煤和交通源(17%)、农业源(13%),还有35%的未知源,推测未知源可能是混合源。对绿地土壤进行环境质量评价,地积累指数和潜在生态危险指数显示Cd和Hg有较高生态风险响应。研究区综合潜在风险值大部分处于轻微和中等潜在生态风险,有少量点位处于重度生态风险。【结论】通州区绿地土壤整体风险等级处于中低风险,引起风险的主要重金属元素为Cd和Hg,二者是生态风险优先控制元素,可从燃煤、交通和工业排放方面进行控制。

基于RF和MLR的土壤重金属影响因素分析及生物有效性预测

为探究影响土壤中重金属累积和生物有效性的因素,以桂北地区某铅锌矿流域为研究对象,综合运用单因子指数法、风险评价编码法(RAC)、多元线性回归模型(MLR)和随机森林模型(RF)进行土壤重金属(Pb、Zn、Cu和Cr)累积影响因素分析及生物有效性预测。结果表明:研究区Cr含量无超标且空间分布相对均匀(变异系数为0.51);Cu、Pb和Zn的含量均值(分别为52.58、280.31 mg·kg^(-1)和654.71 mg·kg^(-1))均大于广西西江流域土壤重金属背景值,在思的河山前和地下河入口处全量和生物有效性均较大,对土壤生态环境具有一定风险;对于重金属全量分布和生物有效态的影响因素,阳离子交换量(CEC)、黏粒(Clay)、土壤有机质(SOM)和铁铝氧化物对Cr影响较大,SOM、Clay、pH和铁铝氧化物对Cu影响较大,pH、电导率(EC)和Clay对Pb影响较大,CEC、pH、土壤质地和铁铝氧化物对Zn影响较大;生物有效性预测结果显示RF和MLR均可较好地预测土壤重金属的全量与次生相,其中RF预测的R2区间为0.44~0.93,MLR预测的R2区间为0.30~0.72,RF预测结果表现更为准确。

微分光谱变换方法对土壤重金属含量反演精度的影响研究

随着我国工农业的日益发展,土壤中以镍(Ni)、铁(Fe)、铜(Cu)、铬(Cr)、铅(Pb)等为代表的重金属污染对人类生活产生了严重影响。高光谱遥感技术具有实时、无损、快速等优点,为高效准确地获取土壤重金属含量提供了科学手段。而在利用高光谱数据反演土壤重金属含量时,微分光谱变换方法的选择对遥感反演土壤重金属含量的精度有显著影响。为明确二者关系,基于研究区采集的60个土壤样品,测定其Ni、Fe、Cr、Cu、Pb等含量以及350~2500 nm波段范围的光谱反射率。在相关系数(CC)分析法的基础上通过改进离散粒子群算法(MDBPSO)优选遥感探测土壤重金属含量的特征波段。最终以优选出的特征波段作为自变量利用随机森林(RF)算法构建了Ni、Fe、Cr、Cu、Pb等重金属含量的估测模型。在对原始反射率数据进行高斯平滑的基础上,对比分析了一阶微分(R′)、对数倒数的一阶微分(1/lgR)′、倒数的一阶微分(1/R)′、指数的一阶微分(e^(R))′四种微分光谱变换方法对土壤重金属反演精度的影响。结果表明,在CC分析法的基础上,MDBPSO算法可以有效地降低光谱数据的冗余度,提高模型的运行效率。其中R′、(1/lgR)′、(1/R)′、(e^(R))′中对Ni、Fe、Cr、Cu、Pb敏感的特征波段个数分别至少减少了154、363、135、744和889个。(1/lgR)′、R′、R′、(1/R)′、R′光谱变换方法分别应用到Ni、Fe、Cr、Cu、Pb特征波段的组合运算中,得到的估测模型的精度优于其他微分变换方法;模型检验集的决定系数分别为0.913、0.906、0.872、0.912、0.876,均方根误差分别为0.743、0.095、2.588、1.541、1.453。本研究为利用遥感数据反演土壤重金属含量微分光谱变换方法的选择提供了科学的参考,为进一步实现土壤重金属含量的大面积高精度遥感监测提供新的思路。

工业用地中土壤重金属污染治理的必要性及治理措施

在工业用地中,土壤重金属污染问题一直是土地治理的研究重点。土壤重金属不仅会导致土地的功能下降,破坏生态环境,而且会直接威胁到人们的生命健康。近年来,随着中国污染治理技术水平的不断提升,土壤重金属污染治理的方法不断增加,从物理治理到化学、生物治理,治理效果的改善有效避免了土壤问题的进一步恶化。基于此,文章从工业用地中土壤重金属污染现状出发,对土壤重金属污染治理的必要性进行分析,并列举常见治理方法,提出相应的土壤重金属污染问题解决策略。

陕西省典型矿区土壤和食用林产品中重金属污染与风险评估

为探明陕西省典型矿区土壤和食用林产品中重金属污染特征与风险情况,通过对渭南华州、商洛柞水县、宝鸡凤县金属矿区土壤和食用林产品进行样品采集并分析测定其As、Hg、Pb、Cd、Cr、Cu含量,采用单因子污染指数法、内梅罗综合污染指数法、土壤和农产品综合质量指数法对土壤和食用林产品重金属污染状况进行评价。结果表明,研究区内土壤均出现不同程度的As、Hg、Pb、Cd、Cr、Cu含量积累;受检食用林产品均出现不同程度的Cr、Cu积累,华州区油松籽2个样品出现Pb含量超标;单因子污染指数表明Cd为凤县研究区土壤的主要污染物,Cr、Cu为柞水县研究区土壤的主要污染物;内梅罗综合污染指数表明凤县和柞水县研究区域土壤为轻度污染状态(质量等级Ⅲ),华州区研究区域土壤为尚清洁状态(质量等级Ⅱ);综合质量影响指数表明,凤县土壤呈现轻微污染(sub-Ⅱ),华州区呈现轻度污染(sub-Ⅲ),柞水县呈现重度污染(sub-Ⅴ)。凤县、华州区和柞水县研究区土壤均出现重金属污染问题,部分食用林产品存在重金属Cr、Cu积累以及Pb超标风险,应及时采取治理修复措施,以缓减土壤和食用林产品的重金属污染问题。

重金属污染土壤修复技术及其修复实践

重金属含量超标会对环境造成严重的破坏,威胁人体健康。因此,在土地资源开发工作开展过程中,应加强对重金属污染土壤的修复,做好日常土壤重金属污染检测工作,制定更加科学的土壤重金属防护措施,使土壤修复技术应用得到大幅度提升。

基于分数阶微分的土壤重金属锌和镍的定量反演模型研究

传统的土壤重金属反演模型通常在预处理中使用整数阶微分方法(如1阶或2阶),其忽略了与目标变量相关的分数阶光谱反射率。分数阶微分(FOD)能通过灵活选定微分阶次,有效增强光谱信号。以云南省普洱市墨江哈尼族自治县的农田土壤为研究对象,测量了61个土壤高光谱反射率和土壤重金属含量数据(锌和镍),对高光谱反射率信息进行了0~2阶(间隔为0.05)分数阶微分预处理,将分数阶微分预处理后的各阶次的光谱反射率输入到连续投影算法(SPA)中进行特征波段筛选;分别建立了偏最小二乘回归(PLSR)、随机森林(RF)和袋装法(Bagging)三种土壤重金属反演模型。结果表明:在经过0到2阶(以0.05为间隔,共41个阶次)的分数阶微分处理,整体光谱强度呈逐渐减弱的趋势,伴随着分数阶阶次的增加逐渐趋向于零。光谱吸收带逐渐收窄,不同光谱曲线之间的差异逐渐减小,随着微分阶次的提高,产生了更为丰富的波峰和波谷。基于分数阶微分的最好阶次模型均优于原始光谱模型和整数阶模型,模型较好阶次大部分集中在低阶分数阶。对于重金属锌,预测模型精度最好的是0.75阶次的RF模型(R^(2)=0.675,RMSE=6.149,RPD=1.755),0.75阶次的Bagging模型次之(R^(2)=0.633,RMSE=6.534,RPD=1.652),0.25阶次的PLSR模型最低(R^(2)=0.551,RMSE=7.230,RPD=1.493)。对于重金属镍,预测模型精度最好的是0.80阶次的RF模型(R^(2)=0.854,RMSE=127.823,RPD=2.618),0.80阶次的Bagging模型次之(R^(2)=0.841,RMSE=133.304,RPD=2.510),0.40阶次的PLSR模型最低(R^(2)=0.762,RMSE=163.162,RPD=2.051)。本研究基于FOD预处理和SPA降维后构建的非线性模型(RF和Bagging)在农田土壤重金属含量估测具有一定的适用性,可以为类似区域的土壤重金属含量反演提供参考依据。