城市土壤中铅地球化学过程与儿童铅暴露的关系

基于文献计量法,探究城市土壤铅地球化学过程研究的关键问题、分析有害金属铅的儿童暴露风险、探索铅污染微生物修复的基础.城市土壤典型有害金属铅生态地球化学过程与机制、生态毒理与低铅暴露效应和风险、污染控制与修复以及相关知识及理论是铅生态地球化学研究的热点和趋势.我国城市土壤典型有害金属铅污染是儿童血铅污染的重要来源,加强城市土壤铅污染治理修复与预防儿童血铅污染和铅中毒是我国城市环境铅污染防控的重要工作内容,急需加强.     

重金属污染土壤生物修复技术研究现状

土壤是生态环境的重要组成部分,与人类的生存和健康密切相关。目前,生物修复技术已开始成为土壤污染修复的主要处理技术。该文系统介绍了重金属污染土壤生物修复的概念、生物修复特点及其机制、类型,重点论述了植物、微生物、动物对重金属污染土壤的修复技术方面的研究进展,并在此基础上提出了一些见解和看法,为今后该方面的研究提供参考。     

土壤重金属污染生态风险评价方法研究进展

城市化所导致的土壤环境恶化已成为影响居民健康的一个重要因素,土壤的重金属污染问题已成为研究的热点。该文综述了目前常用的土壤重金属污染生态风险评价方法 [形态分析法、TCLP(Toxicity characteristic leaching procedure)法、体外试验评估法、植物培养法、蚯蚓生态毒理法]。指出今后的研究重点是制定土壤重金属环境质量标准和建立完善的评价体系,确定植物重金属污染指示作用的重要性,利用地理信息系统(GIS)技术开展重金属污染填图及建立土壤重金属污染信息系统,这些研究可为土壤管理提供科学指导依据。     

湖北省农田土壤重金属铅、镉、铬的健康风险评估研究

目的对湖北省400份农田土壤状况进行重金属污染程度评价,为今后湖北省制定土壤污染防治和健康风险防范相关政策提供依据。方法采用污染指数法、生态及健康风险评价等方法进行评价。结果湖北省土壤铅、镉和铬3种重金属元素的污染程度大小为CdCrPb,潜在生态风险评价有9份土壤存在中及重度危险,整体潜在生态风险综合指数11.31,属于轻微生态污染,儿童和成人总非致癌风险指数均小于1,镉的致癌风险指数低于10~(-6)。结论本次调查的湖北省农田土壤整体评价在清洁水平范围内,符合农用地土壤标准,且3种重金属污染导致的健康风险均在可接受范围内。本次调查评估还存在不少局限性,重金属污染的源头及其风险评估仍有待进一步研究。     

湖北省农田土壤重金属铅、镉、铬的健康风险评估研究

目的对湖北省400份农田土壤状况进行重金属污染程度评价,为今后湖北省制定土壤污染防治和健康风险防范相关政策提供依据。方法采用污染指数法、生态及健康风险评价等方法进行评价。结果湖北省土壤铅、镉和铬3种重金属元素的污染程度大小为Cd>Cr>Pb,潜在生态风险评价有9份土壤存在中及重度危险,整体潜在生态风险综合指数11.31,属于轻微生态污染,儿童和成人总非致癌风险指数均小于1,镉的致癌风险指数低于10~(-6)。结论本次调查的湖北省农田土壤整体评价在清洁水平范围内,符合农用地土壤标准,且3种重金属污染导致的健康风险均在可接受范围内。本次调查评估还存在不少局限性,重金属污染的源头及其风险评估仍有待进一步研究。     

基于双聚类和可视化的重金属污染领域研究热点探析

目的 探究2006-2015年间国内重金属污染领域文献的研究热点.方法 以中国知网数据库重金属污染的文献数据为研究对象,采用BICOMB软件生成70个高频关键词的词篇矩阵,将该矩阵导入gCLUTO软件中进行双聚类分析并可视化,得到重金属污染的研究热点.结果 重金属污染文献聚类结果主要集中在5个方面.包括重金属污染对农作物的影响;重金属污染造成的生态风险及评价;植物对重金属污染的防治作用;土壤重金属的生物有效性;重金属污染造成的食品安全及人体健康风险问题.结论 通过双聚类分析和可视化,可以得出当前重金属污染领域的研究热点,从而为科研人员和环保部门提供一定的参考依据.     

六盘水市不同功能区土壤重金属蓄积特征及人群健康风险评估

目的了解六盘水市不同功能区表层土壤中重金属的污染状况。方法于2014年3—11月,采集六盘水市居民区、商业区、科教区、城市主干道、公共区5个功能区表层土壤,检测Cd、Hg、As、Cu的含量,并采用污染负荷指数法对其污染特征进行分析,并结合美国环保署(USEPA)健康风险评估模型对其健康风险进行评估。结果六盘水市土壤中Cd、Hg、As、Cu含量均值均超出了贵州省土壤背景值,其中,Hg的超标最严重。各功能区的整体污染程度依次为公共区文教区商业区城市主干道居民区。5个功能区重金属对成人产生的非致癌总风险(HI)均小于1,不存在显著的非致癌风险;对儿童产生的HI均大于1,存在显著的非致癌风险。城市主干道土壤中4种重金属对儿童的致癌总风险(RISKT)10~(-4),存在显著的致癌风险,其它功能区对儿童和成人的RISKT介于10~(-6)～10~(-4)之间,可能存在一定的致癌风险。各功能区的HI及RISKT表现为城市主干道公共区居民区文教区商业区。手-口摄入是人群暴露于重金属的主要途径,且儿童的HI及RISKT均高于成人。结论该研究区污染程度大致表现为由西南向东北增加的趋势,公共区达到极强污染,重金属对儿童的健康风险程度高于成人。     

兰州市土壤重金属污染特征及其健康风险评价

目的探讨兰州市土壤重金属污染特征并进行健康风险评价。方法于2016年9月对兰州市城关区和榆中县居民生活区各设置13个采样点,共采集表层土壤样本60个,检测18种重金属含量;采用地累积指数评价污染程度,采用美国EPA推荐的模型进行健康风险评价。结果调查地区土壤Se和Hg达到中等-重污染水平,Cd也达到中等污染水平,城市土壤中Zn和Pb也达到轻-中等污染,除此之外,其它重金属均未造成污染。成人和儿童的多重金属暴露的综合非致癌风险分别为0.138和0.917,综合致癌风险分别为1.75×10~(-6)(As的经口暴露:1.51×10~(-6))和5.97×10~(-7)。结论应进一步加强当地土壤重金属污染的防控,尤其关注土壤As的污染。     

镉污染土壤植物萃取技术的研究进展

植物萃取是指在受重金属污染的土壤上连续的种植专性植物并收割植物茎叶作离地处理 ,以降低土壤中的重金属浓度的新兴技术。利用此方法对镉污染土壤进行原位修复具有成本低、环境可持续性的优点。综述了近年来这一领域内的研究进展及其商业应用的可行性分析 ,并展望了此技术在我国的应用前景。     

干旱区绿洲土壤-油菜系统重金属污染实验研究

为研究干旱区绿洲土壤重金属的复合污染对油菜的影响及其对人体造成的潜在健康风险,制备低剂量重金属污染土壤(Cd:0.75mg/kg,Zn:100mg/kg,Pb:150mg/kg)和高剂量重金属污染土壤(Cd:2.50mg/kg,Zn:450mg/kg,Pb:450mg/kg)进行盆栽试验。结果显示,所有油菜样品中Zn含量均未超过GB13106—1991规定限值;Pb、Cd含量最大值分别为2.63和0.35mg/kg,超过GB18406.1—2001规定限值。高剂量重金属污染土壤种植的油菜中Pb、Cd摄入的健康风险指数分别为7.01和7.25,存在严重的健康风险。     

Nitrogen and Phosphorus Fertilizer Increases the Uptake of Soil Heavy Metal Pollutants by Plant Community

Soil heavy metal pollution is widespread around the world. Compared with hyperaccumulation plants, non-hyperaccumulator plant communities have many advantages in the remediation of heavy metals pollution in soil. The application of nitrogen (N) and phosphorus (P) is inexpensive and convenient, which can promote the growth of plant. N and P fertilizer might increase plant community remediation of heavy metal polluted soils. In our study, the effects of N and P fertilizer on remediation of soil Cd, Cu, Pb pollution by plant community were studied through a greenhouse experiment. Our results indicated that addition of N, P and N?+?P fertilizer increased plant community aboveground biomass. Simultaneously, addition of N and P fertilizer increased the accumulation of heavy metals in aboveground of the plant community and accelerated plants absorption soil heavy metals. Among them, N fertilizer had the best effect. Our results provide an inexpensive method for remediation heavy metal pollution of contaminated farmland, abandoned land and mine tailings, etc.

     

Spatial variations of heavy metals in the soils of vegetable-growing land along urban-rural gradient of Nanjing, China

China has experienced rapid urbanization in recent years. The acceleration of urbanization has created wealth and opportunity as well as intensified ecological and environmental problems, especially soil pollution. Our study concentrated on the variation of heavy metal content due to urbanization in the vegetable-growing soil. Laws and other causes of the spatial-temporal variation in heavy metal content of vegetable-growing soils were analyzed for the period of urbanization in Nanjing (the capital of Jiangsu province in China). The levels of Cu, Zn, Pb, Cd and Hg in samples of vegetable-growing soil were detected. The transverse, vertical spatio-temporal variation of heavy metals in soil was analyzed on the base of field investigations and laboratory analysis. The results show that: (1) in soil used for vegetable production, the levels of heavy metals decreased gradually from urban to rural areas; the levels of the main heavy metals in urban areas are significantly higher than suburban and rural areas; (2) the means of the levels of heavy metals, calculated by subtracting the sublayer (15-30 cm) from the toplayer (0-15 cm), are all above zero and large in absolute value in urban areas, but in suburban and rural areas, the means are all above or below zero and small in absolute value. The causes of spatial and temporal variation were analyzed as follows: one cause was associated with mellowness of the soil and the length of time the soil had been used for vegetable production; the other cause was associated with population density and industrial intensity decreasing along the urban to rural gradient (i.e., urbanization levels can explain the distribution of heavy metals in soil to some extent). Land uses should be planned on the basis of heavy metal pollution in soil, especially in urban and suburban regions. Heavily polluted soils have to be expected from food production. Further investigation should be done to determine whether and what kind of agricultural production could be established near urban centers.     

Sorption of toxic heavy metals to soil

The surface soil is a major recipient of pollutants, including heavy metals, through atmospheric deposition, agricultural practices, and waste disposal. In the present work the sorption capacity of different types of soils to toxic heavy metals, i.e. chromium, copper, cadmium and lead has been studied. Experimental adsorption data for metals to the soil obtained by the batch method were fitted by linear isotherm. The various soils showed a very different behaviour in sorption of heavy metals. The distribution coefficient Kd, which is an indication of the adsorbing capacity of the substrate, varies within a wide range, from 57 to 53,000 l kg-1. Desorption of metals from the solid phase was found to be small, indicating that the soil matrix is affecting the metal mobility by modifying the bonding of pollutants to the soil system consequently affecting the potential for soil remediation processes.     

Metal Tolerance Capability of <Emphasis Type="Italic">Helichrysum microphyllum</Emphasis> Cambess. subsp. <Emphasis Type="Italic">tyrrhenicum</Emphasis> Bacch., Brullo &amp; Giusso: A Candidate for Phytostabilization in Abandoned Mine Sites

Sardinia was known as an important mine pole in Europe during his history. Still after decades from mine closure, 75.000.000 m³ of mine waste, rich in heavy metals, were left abandoned causing a huge environmental legacy on the mine district area. Consequently, cost effective remediation is required. In this frame, phytoremediation is considered a feasible candidate. This research was focused on Helichrysum microphyllum subsp. tyrrhenicum, which is pioneer in xeric soils with low-functions, like mine tailings. The aim of this study was to evaluate its ability to extract heavy metals from mine soils and accumulate them in plant tissues and its suitability for phytostabilization. Sundry samples of soil, roots and epigean organ were collected through field sampling and analysed in order to obtain metals concentration and mineralogical characteristics. Our results indicate that this species tolerates high concentration of zinc, lead and cadmium, behaving as a species suitable for phytostabilization.     

Impact of heavy metal toxicity and constructed wetland system as a tool in remediation

The objective of this review is to throw light upon the global concern of heavy metal–contaminated sites and their remediation through an ecofriendly approach. Accumulated heavy metals in soil and water bodies gain entry through the food chain and pose serious threat to all forms of life. This has engendered interest in phytoremediation techniques where hyperaccumulators are used. Constructed wetland has a pivotal role and is a cost-effective technique in the remediation of heavy metals. Metal availability and mobility are influenced by the addition of chelating agents, which enhance the availability of metal uptake. This review helps in identifying the critical knowledge gaps and areas to enhance research in the future to develop strategies such as genetically engineered hyperaccumulators to attain an environment devoid of heavy metal contamination.     

A Multidisciplinary Approach to Assess History, Environmental Risks, and Remediation Feasability of Soils Contaminated by Metallurgical Activities. Part A: Chemical and Physical Properties of Metals and Leaching Ability

Three soils contaminated by heavy metals (HMs) and aliphatic hydrocarbons originating from different industrial sources were characterized in a multidisciplinary study combining chemical, physical (Part A), and mineralogical (Part B) approaches to define history, environmental risks, and remediation feasibility. These were an agricultural soil located nearby a Zn/Pb smelter and two soils from a steel metallurgical (siderurgy) waste land. High Pb and Zn contents were reported for all, and high Cr, Cd, and aliphatic hydrocarbons were present in different combinations in two out of three soils. Carbonate matrixes more strongly cemented fine particles in the agricultural soil than in both siderurgical ones, but buffering capacities were stronger in the latter. After the disruption of these cements by ultrasounds, HM were concentrated in the <50-μm fraction of the agricultural and of one siderurgical soil. Sequential extractions indicated for all the soils a preferential association of HM with carbonates, Fe-Mn oxides, organic matter, and sulfides. The stirring of one siderurgical soil with water resulted in an immediate leaching of hexavalent chromium (0.3 mg · L⁻¹) involving potential ecotoxicological risks. Received: 17 August 1999/Accepted: 24 November 1999     

Risk assessment of heavy metals in finer than 63-μm dust particles from various functional areas in Xi’an,China

Heavy metals Pb, Cr, Zn, Cu, Co, Mn, and Ni in the dust particles finer than 63 μm from four functional areas of Xi’an, i.e., residential area, educational area, park area, and traffic area, were measured using X-ray fluorescence spectrometry. The risks of these heavy metals to urban ecosystem and human health were evaluated by the potential ecological risk index and human exposure model, respectively. Compared with Shaanxi soil, the finer dust particles have elevated metal concentrations, except for Co, Mn, and Ni. All analyzed heavy metals have different variation characteristics in four functional areas. The ecological risks of Cr, Zn, Cu, Co, Mn, and Ni in the samples were at lower levels, while the presence of Pb was high. The overall ecological risks of heavy metals measured in the samples were moderate level, which were mainly caused by Pb and Cu. Health risk assessment shows that ingestion was the main exposure route of all analyzed heavy metals in the dust particles finer than 63 μm to children and adults. The non-cancer risks of the heavy metals to children and adults were within the safe range, and the cancer risks of Cr, Co, and Ni were also within the currently acceptable range.     

Sources and Assessment of Mercury and Other Heavy Metal Contamination in Soils Surrounding the Wuda Underground Coal Fire Area,Inner Mongolia,China

Concentrations of mercury and other heavy metals were measured in soils surrounding the Wuda Coalfield, Inner Mongolia where underground coal fires are regarded as an important contamination source. Soil samples at the downwind direction were nearly all enriched mercury in surface layers, with their concentrations ~ 10 times higher than those from upwind soils. Mercury concentrations generally increased along soil profiles upward, indicative of increasing atmospheric mercury deposition in recent decades. We suggest that underground coal fire emissions were the potential mercury contamination source and the key factor controlling mercury enrichment in soils. Other heavy metals showed no clear spatial and vertical trends, suggesting that underground coal fire emissions may not the main factor for their enrichment in soils. Antimony showed the highest enrichment followed by tin, while chromium, mercury and cadmium only exhibited slight enrichment. Risk evaluation indicated that heavy metals in the studied soils pose no ecological threats.

     

Effect of boiling and grilling on some heavy metal residues in crabs and shrimps from the Mediterranean Coast at Damietta region with their probabilistic health risk assessment

The goal of the current research was to study the effect of cooking on the residual contents of toxic heavy metals in crabs (12−14 cm CW) and shrimps (25–35/pound) samples widely consumed in Mansoura city, Egypt, along with assessment of public health risks associated with consumption of these crustaceans contaminated with such metals. The atomic absorption spectrophotometer detected arsenic (As), mercury (Hg), cadmium (Cd) and lead (Pb) in all tested samples by different levels, but the majority of samples contained heavy metals by levels exceeded the Egyptian MPLs. Our results showed that cooking of crustaceans either by boiling or grilling effectively reduced heavy metals contents. The results of health risk assessment indicated that the consumption of crabs and shrimps marketed in Egypt may carry potential health risks for consumers. Although cooking effectively reduced heavy metals in crabs and shrimps, the non-carcinogenic risks still present in this foods and couldn’t be totally eliminated. Therefore, in order to reduce the heavy metals content of the crustaceans, in addition to applying efficient cooking processes such as boiling and grilling, stringent control measures should be followed to avoid contamination of crustaceans with toxic heavy metals and to confirm that their concentrations didn’t overdo their legal limits.