单一及复合重金属污染对土壤酶活性的影响

采用外源添加重金属和室内培养的方法研究重金属Cd、Pb对滩涂盐渍土脲酶、过氧化氢酶活性的影响,为中国沿海地区土壤重金属污染的监测及重金属对潜在生态环境影响等方面的研究提供参考依据。重金属Cd添加至土壤的质量分数为0、0.5、1.0、2.0 mg.kg-1,重金属Pb添加至土壤的质量分数为0、100、200、400 mg.kg-1,采用完全随机区组设计,3次重复。结果表明：重金属质量分数较低时,单一重金属对土壤脲酶活性具有促进,对过氧化氢酶活性具有抑制作用;重金属质量分数较高时,对土壤脲酶活性具有抑制作用,对土壤过氧化氢酶具有促进作用。重金属Cd、Pb对土壤酶活性的影响存在交互作用,重金属Cd对土壤脲酶活的性影响起主导作用,重金属Pb对土壤过氧化氢酶活性的影响起主导作用。经逐步回归分析,有效态重金属的质量分数低水平时,土壤脲酶活性与重金属Cd呈现显著负相关;土壤过氧化氢酶活性与重金属Pb呈现显著正相关。     

土壤重金属的生物有效性和环境质量标准

本文根据文献资料和一些试验结果,对国内外土壤重金属环境质量标准的研究现状和土壤重金属生物有效性的主要影响因素作了简要介绍,比较了以土壤重金属总量、有效含量和综合指标来评价土壤重金属生物生态效应的优缺点。这些分析比较表明,影响土壤重金属生态效应的因素很多,以土壤重金属总量为单一指标评价土壤重金属污染水平是不够的,以中性盐浸提剂测得的土壤有效含量可能是一种良好指标,而以土壤重金属总量结合土壤pH的综合指标则比较经济、合理和可行。本文也提出了一种pH修正总量指标。     

长三角和珠三角农业土壤对Pb、Cu、Cd的吸附解吸特性

研究了长江三角州和珠江三角州10种代表性农业土壤对重金属Pb、Cu和Cd的吸附与解吸特性。结果表明:大多数土壤对重金属有较强吸附能力,土壤性质对重金属吸附与解吸行为有很大影响。其中,pH值是影响土壤对重金属吸附与解吸的最重要因素,土壤重金属吸附量随pH值增加而增加。土壤pH值和有机质或粘粒含量较高的土壤(如乌栅土、青紫泥田、黄斑田),其对重金属吸附能力高于pH值和有机质或粘粒含量较低的土壤(如黄筋泥、粉泥田)。重金属解吸量随重金属吸附量和土壤重金属饱和度增加呈指数增加趋势;土壤对重金属的吸附能力从强至弱依次为Pb、Cu、Cd;当3种重金属共存时,重金属之间竞争能力强弱顺序与吸附能力顺序相同。重金属之间竞争作用随土壤酸度和重金属污染程度的增加而增强。     

中国土壤重金属污染修复技术的专利文献计量分析

综述了国内外主要土壤修复技术,进行了技术经济比较分析。利用国家知识产权局专利检索系统,采用主题词检索,从重金属污染物种类、技术类型两个方面分析了中国土壤重金属污染修复技术的专利申请与授权状态。结果表明：土壤重金属污染修复技术以植物修复与微生物技术为主,其次为固定修复技术;土壤镉、铅、铜、砷的修复技术专利申请量明显高于其余重金属的;农田土壤重金属污染修复技术专利申请量明显高于场地重金属修复技术的;农田土壤重金属污染修复除降低土壤中重金属含量外,还可以从植物营养调控与土壤调理剂的角度降低农产品中重金属含量。最后,进行了土壤污染修复产业政策分析。     

北京市凉水河污灌区土壤重金属累积和形态分析

采用野外定点连续采样和室内分析相结合的方法,对北京市凉水河污灌区土壤中Cu、Zn、Cr、Pb、Ni等重金属在土壤中的累积及其化学形态进行了系统研究.结果表明,①凉水河污灌区土壤中重金属的质量分数均高于北京地区的土壤背景值,特别是Cu和Pb分别达到北京市土壤环境背景值的3.47倍和4.53倍,凉水河污灌区土壤已经发生明显的重金属累积.②土壤重金属元素之间相关分析表明研究地区存在重金属复合污染,土壤有机质与土壤重金属显著相关表明污灌可能是导致土壤重金属富集的重要原因;土壤各理化性质与土壤重金属相关性表现不一致,土壤重金属富集与迁移的影响因素复杂多样.③Tessier连续提取法测定土壤5种重金属的形态分布规律均为:残渣态>铁锰结合态>有机结合态>碳酸盐结合态>可交换态,铁锰结合态含量较高与污水中铁锰含量较高具有一定的关系;凉水河污灌区重金属潜在迁移能力顺序为:Cu>Zn>Pb>Ni>Cr.④综合分析各土壤重金属富集状况、形态分布及其生态毒性,Cu和Pb是凉水河污灌区土壤中需要优先控制的重金属.     

中国蔬菜地土壤重金属健康风险基准的研究

对我国目前土壤和蔬菜中重金属污染评价情况进行了综述,根据全国已报道蔬菜地土壤和蔬菜中重金属含量的数据和相关资料,探讨了蔬菜地土壤和蔬菜中重金属含量之间的关系以及不同的蔬菜种类和品种中重金属的积累差异,并在已有土壤和蔬菜中重金属污染的评价指标基础上,对蔬菜地土壤和蔬菜中重金属的健康风险基准值进行了讨论,尤其对我国各地区蔬菜地土壤中重金属的污染指标值进行了统一的限定,可为制订蔬菜地土壤重金属健康风险标准提供科学依据.     

土壤酶与重金属关系的研究现状

介绍了近年来土壤酶与重金属关系的研究动向,以及重金属对酶活性作用的影响因素;探讨了用土壤酶表征重金属污染程度的方法及其可行性。有关研究表明,不同土壤酶类对重金属的敏感性有明显差异;土壤酶活性特别是总体酶活性作为污染指标是可行的;土壤酶与重金属的关系主要取决于土壤有机质、粘粒等含量的高低及它们对土壤酶的保护容量和对重金属缓冲容量的大小。文中还分析了研究中应注意的问题。     

中国城市土壤重金属污染研究现状及对策

中国城市土壤重金属污染的主要来源是工业“三废”排放，金属采矿和冶炼，家庭燃煤，生活垃圾，汽车尾气排放。重金属在城市土壤中的分布规律表现为城市土壤重金属含量高于郊区，人类活动密集区和交通拥挤区重金属含量较高；人类活动的干扰导致土壤剖面重金属污染特征不明显。应采取预防与治理相结合的措施综合控制土壤重金属污染，并加紧制定我国的城市土壤健康评价标准。     

土地利用/覆被变化（LUCC）与土壤重金属积累的关系研究进展（Research Review of the Relationship between Land Use/Cover Change and Heavy Metal Accumulation in Soil）

土壤重金属污染是世界性环境问题之一.土地利用/覆被变化(LUCC)是最主要的环境演变驱动因子之一.为明晰LUCC对土壤重金属积累和污染的影响,根据前人研究,从场地、县域和流域/区域尺度总结了LUCC和土壤重金属污染的关系.研究发现,三个尺度上土地利用方式和覆被类型/格局是控制土壤重金属空间积累和分布的重要因子,土地利用/覆被可以直接吸纳或吸附重金属,亦能通过改变土壤物理、化学和生物性质从而控制重金属在土壤中的移动性和活性,造成土壤中重金属的积累直至污染.此外,论文阐明了LUCC在土壤重金属污染风险预测、规避和污染土壤修复中的重要作用,最后提出了在实践中通过调整土地利用/覆被类型进行污染土壤修复的建议.寓景观生态学思想于土壤重金属污染防治过程是一种新的有效途径.     

不同环境下土壤作物系统中重金属元素迁移分配特点

不同环境中重金属的积累特点及其向食物的迁移可能导致对人类健康的不同影响。文章对苏南某市典型乡镇工业环境中的农田表层土壤重金属污染积累进行了分析,并参照国家土壤环境质量二级标准进行重金属污染的单因子和综合因子评价。结果表明,工业环境中农田土壤表层重金属元素的富集系数和重金属DTPA有效态含量显著高于非工业环境,说明工业化发展是土壤重金属积累的主要因素,同时土壤的基本理化性质对土壤重金属的富集有一定的影响。不同种类农产品对重金属的富集能力表现为叶菜类>籽实类>根菜类>水稻籽粒,重金属元素中Cd、Zn、Cu较易在农产品中积累。应该注意工业发展对农田土壤的重金属污染以及对人类食物安全的可能影响。     

汽车尾气中铅对公路两侧土壤的污染特征

采用一系列的实验室质量保证措施，利用统计学原理，研究了汽车尾气中铅对公路(以102国道长春至四平段远离城市且周围无工业点源为例)两侧土壤污染的程度，并分析了其分布水平。结果表明公路两侧土壤铅的污染在公路两侧30-35m范围内较为严重，说明土壤主要受汽车尾气中铅的污染影响，而距公路75m以外，汽车尾气中的铅对土壤基本无影响。对土壤铅含量垂直分布的研究表明，随着土壤深度增加，铅含量迅速减少，距地面10cm以下时，即达到土壤背景值的下限。     

Assessment of the pollution and ecological risk of lead and cadmium in soils

The aim of the study was to assess the content, distribution, soil binding capacity, and ecological risk of cadmium and lead in the soils of Malopolska (South Poland). The investigation of 320 soil samples from differently used land (grassland, arable land, forest, wasteland) revealed a very high variation in the metal content in the soils. The pollution of soils with cadmium and lead is moderate. Generally, a point source of lead and cadmium pollution was noted in the study area. The highest content of cadmium and lead was found in the northwestern part of the area—the industrial zones (mining and metallurgical activity). These findings are confirmed by the arrangement of semivariogram surfaces and bivariate Moran’s correlation coefficients. Among the different types of land use, forest soils had by far the highest mean content of bioavailable forms of both metals. The results showed a higher soil binding capacity for lead than for cadmium. However, for both metals, extremely high (class 5) accumulation capacities were dominant. Based on the results, the investigated soils had a low (Pb) and moderate (Cd) ecological risk on living components. Soil properties, such as organic C, pH, sand, silt, and clay content, correlated with the content of total and bioavailable forms of metals in the soils. The correlations, despite being statistically significant, were characterized by very low values of correlation coefficient (r?=?0.12–0.20, at p?≤?0.05). Therefore, the obtained data do not allow to define any conclusions as to the relationships between these soil properties. However, it must be highlighted that there was a very strong positive correlation between the total content of cadmium and lead and their bioavailable forms in the soils.     

Use of a physiologically based extraction test to estimate the human bioaccessibility of potentially toxic elements in urban soils from the city of Glasgow,UK

A simple, two-stage, physiologically based extraction has been applied to assess the human bioaccessibility of potentially toxic elements (PTE) in 20 urban soils from a major UK city. Chromium and iron bioaccessibilities were found to be markedly higher in the intestinal phase, whilst lead and zinc bioaccessibilities were higher in the stomach. Copper and manganese bioaccessibilities were generally similar under both extraction conditions. Principal component analysis was used to study relationships amongst bioaccessible element concentrations and land use. Distinctions could be observed between the distributions of the urban metals—copper, lead and zinc—and metals predominantly of geogenic origin, such as iron. There was no clear delineation between roadside soils and soils obtained from public parks. Bioaccessible analyte concentrations were found to be correlated with pseudototal (aqua regia soluble) analyte concentrations for all elements except iron. Results of the BCR sequential extraction did not, in general, provide a good indication of human bioaccessibility. Comparison of bioaccessible PTE concentrations with toxicological data indicated that lead is the element of greatest concern in these soils but that levels are unlikely to pose a health risk to children with average soil intake.     

Human bioaccessibility of Cr, Cu, Ni, Pb and Zn in urban soils from the city of Torino, Italy

Several physiologically based extraction procedures have been proposed to estimate the fraction of the potentially toxic element content that would be bioaccessible in the human gastro-intestinal tract following accidental ingestion of soil. Many of these procedures are complex, they have been applied to a very limited range of soils, and most work has focussed on arsenic and lead. In the present study, a simplified, two-stage extraction, simulating the human stomach and intestine, was developed and applied to urban soil samples from ten public-access areas in the City of Torino, Italy. The human oral bioaccessibility of chromium, copper, nickel, lead and zinc was estimated. Lead and zinc bioaccessibilities were found to be higher in the stomach, but chromium was more bioaccessible in the intestine. Analyte concentrations were higher in roadside soils than in soils from parks. A higher proportion of the soil metal content was found in bioaccessible forms at roadsides than in parks. Comparison of the current findings with results of earlier work involving sequential extraction of the same soils indicated that the sequential procedure gave a relative, but not an absolute, indication of bioaccessibility. Calculations based on the bioaccessible analyte concentrations suggest that ingestion of only 2–3 g of some of the roadside soil samples from Torino could deliver the tolerable daily oral intake of chromium, nickel and lead to a 20-kg child. The developed procedure is useful for preliminary screening of soils and prediction of whether their bioaccessible metal contents are likely to pose a risk to human health.     

Ecological risk assessment from the perspective of soil heavy metal accumulations in Xiamen city,China

Contamination of soils by heavy metals is of rising concern in many cities in China undergoing rapid urbanization. Here, we evaluate the severity of soil contamination by four heavy metals (arsenic, chromium, copper, and lead) at 146 urban and suburban sites within the city of Xiamen, Fujian, China. A multivariate regression model was proposed and developed to simulate heavy metals accumulation in urban and suburban soils, to identify the concentration and spatial distribution of heavy metals in soils, and to assess ecological risks by 2020. Results showed that, overall, Xiamen soils should be subject to low ecological risks due to heavy metals contamination by 2020, the ecological risks for urban soils were greater than suburban soils, nearly half of Xiamen soils are at moderate ecological risks, and many suburban soils experience low ecological risks. The methods demonstrate the potential to predict future ecological risks from heavy metals contamination which could inform pollution prevention and control measures.     

Heavy metal migration in soils and rocks at historical smelting sites

The vertical migration of metals through soils and rocks was investigated at five historical lead smelting sites ranging in age between 220 and 1900 years. Core samples were taken through metal-contaminated soils and the underlying strata. Concentration profiles of lead and zinc are presented from which values for the distances and rates of migration have been derived. Slag-rich soil horizons contain highly elevated metal concentrations and some contamination of underlying strata has occurred at all sites. However, the amounts of lead and zinc that have migrated from soils and been retained at greater depths are comparatively low. This low metal mobility in contaminated soils is partly attributed to the elevation of soil pH by the presence of calcium and carbonate originating from slag wastes and perhaps gangue minerals. Distances and rates of vertical migration were higher at those sites with soils underlain by sandstone than at those with soils underlain by clay. For sites with the same parent material, metal mobility appears to be increased at lower soil pH. The mean migration rates for lead and zinc reach maxima of 0.75 and 0.46 cm yr^–1 respectively in sandstone at Bole A where the elements have moved mean distances of 4.3 and 2.6 m respectively. There is some evidence that metal transport in the sandstone underlying Bole A and Cupola B occurs preferentially along rock fractures. The migration of lead and zinc is attenuated by subsurface clays leading to relatively low mean migration rates which range from 0.03 to 0.31 cm yr^–1 with many values typical of migration solely by diffusion. However, enhanced metal migration in clays at Cupola A suggest a preferential transport mechanism possibly in cracks or biopores.     

Floristic variation in plant communities on metalliferous mining residues in the northern and southern Pennines,England

Vegetation and soil surveys were conducted on metalliferous mine wastes in the northern and southern Pennines of England. Analyses of vegetation composition in relation to soil chemical variation were performed. Ordination analysis facilitated the detection of groups of co-occurring species which are characteristic of types of metal-contaminated soil. The results of regression analysis implied the importance of soil pH and concentration of available lead or zinc, depending upon region, in determining species distributions. A strong interactive effect was evident between soil phosphorus and zinc content in influencing species distributions in the southern Pennines sample.Regional similarities in the vegetation of apparently similar metalliferous soils existed. The unusually high species richness of some soils was associated with relatively low concentrations of heavy metals. Many species of relatively floristically-rich wastes were also colonists of surrounding grasslands or woodland. This indicated the potential importance of propagule availability and capability for rapid establishment on bare or unstable ground. Mechanisms of physiological stress avoidance, rather than heavy-metai tolerance, may explain the occurrence of non-metallophytes on soils contaminated with lead and zinc.     

Lead contamination in the roadside soils of Slovenia

The level of lead contamination along the roadway Ljubljana to Zagreb was established in 184 soil samples. The samples were taken from two depths (0–5cm and 15–20cm) and at different distances from the roadway. The influence of terrain morphology, prevailing winds, geological parent material and type of vegetation was estimated. Heavy traffic is confirmed as main source of lead contamination (average enrichment factor 17) in soils. The highest lead accumulation is localised in the top soil layer and within 10m from the roadside. Contamination with lead is more pronounced in soil samples from cuttings and slopes than in soils from plains and mounds. Soils derived from carbonate rocks contain higher lead concentration than those derived from other parent material.     

Mitigation and remediation technologies for organic contaminated soils

Organic contaminated soils have become a widespread environmental problem, which may lead to a great threat to the quality of agricultural production and to human health. Physical, chemical, and biological technologies have been employed for the mitigation and remediation of organic contaminated soils. This paper reviews the progress of mitigation and remediation technologies for organic contaminated soils and suggests two different strategies for the mitigation of ’slightly-contaminated’ agricultural soils and the remediation of ‘heavily-contaminated’ soils/sites, respectively. On this basis, directions for future research in this field are suggested.     

干旱区绿洲土壤中重金属的形态分布及生物有效性研究

测定了Cd、Pb、Zn和Ni等重金属在不同处理土壤中的全量和各赋存形态,以及它们在盆栽试验油菜（Brassica cole）中的质量分数,并利用Pearson相关系数分析了该区土壤-油菜体系的生物有效性。结果表明,供试绿洲土壤原状土中,Cd、Pb、Zn和Ni均以稳定的残渣态形式存在;而在处理土壤中,重金属被钝化的量有限,Cd的存在形式主要以碳酸盐态为主,Pb、Zn和Ni则主要以铁锰氧化态为主。根据相关性分析,油菜根部和叶部的Ni质量分数均与土壤中Ni的各非残渣态分布系数有相关性,表明当土壤中Ni以非残渣态存在时,活动性Ni的质量分数较高,其被生物吸收利用的可能性也较大;油菜根部的Zn质量分数与土壤中Zn的碳酸盐结合态分布系数显著的正相关性;油菜各部位Cd和Pb的质量分数与土壤中Cd和Pb的各形态分布系数之间无显著相关关系。