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1.
南京市城郊零散菜地土壤及青菜中重金属含量特征 总被引：4，自引：0，他引：4
丁爱芳 《南京晓庄学院学报》2003,19(4):28-31
采集了南京市城郊零散菜地土壤和青菜配对样品各18个,用原子吸收光谱仪测定了其中铜、锌、铅、镉的含量,结果表明:南京市城郊菜地土壤中Cu、Zn、Pb、Cd全量高于农区菜地土壤,Cu、Zn达到显著差异,重金属含量在土样之间有较大的变异性,反映了人为活动已对南京城郊土壤重金属产生了明显影响。城郊土壤上种植的青菜其可食部分重金属含量高于农区,尤其是对人体健康影响较大的Pb、Cd含量与农区相比存在显著差异,大大超过国家食品卫生标准。 相似文献
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哈尔滨市柳树林垃圾场垃圾渗滤液对周边土壤污染状况的调查 总被引：2，自引：0，他引：2
在由于城市的发展人口的增加,垃圾产生量逐渐增多,产生的垃圾渗滤液对垃圾场底部及其周围的土壤、地下水造成了严重的污染。通过对污染土壤样品的调查分析,结果表明：在水平方向,垃圾堆放场周围200m范围土壤被严重污染；在垃圾场底部垂直方向,随着深度的增加垃圾渗滤液的含量逐渐的减少,在6m处含量收敛于背景值。 相似文献
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钾离子在粘性土中扩散运移的影响因素 总被引：2，自引：0，他引：2
为了研究日本九州地区的2种区域性土———有明粘土和赤土作为废弃物填埋场底部粘土衬垫层的适应性,做了一系列室内扩散试验.应用软件Pollute V6·3模拟计算了实验结果,反算出了钾离子的扩散系数.研究结果表明,有明粘土的扩散系数比赤土的扩散系数小,说明有明粘土有望能作为更合适的粘土衬垫材料.通过对比试验研究,发现在混合溶液的情况下,钾离子的扩散系数较在单一溶液的钾离子的扩散系数小.因此建议尽可能使用与现场淋滤液成分相近的混合溶液来做扩散试验,以求出扩散系数来作为废弃物填埋场的设计和性能评估参数. 相似文献
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INTRODUCTION Regulation, handling and bioremediation of hazardous materials require an assessment of the risk to some living species other than human being, or assessment of hazard to the entire ecosystem. As- sessment endpoints are values of the ecosystem that are to be protected and are identified early in the analysis. Such endpoints may include life cycle stages of a species and reproductive or growth patterns. Ecosystem risk assessment is at its dawn with this area of environment sci… 相似文献
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Assessing potential dietary toxicity of heavy metals in selected vegetables and food crops 总被引：3，自引：0，他引：3
Heavy metals, such as cadmium, copper, lead, chromium and mercury, are important environmental pollutants, particularly in areas with high anthropogenic pressure. Their presence in the atmosphere, soil and water, even in traces can cause serious problems to all organisms, and heavy metal bioaccumulation in the food chain especially can be highly dangerous to human health. Heavy metals enter the human body mainly through two routes namely： inhalation and ingestion, ingestion being the main route of exposure to these elements in human population. Heavy metals intake by human populations through food chain has been reported in many countries. Soil threshold for heavy metal toxicity is an important factor affecting soil environmental capacity of heavy metal and determines heavy metal cumulative loading limits. For soil-plant system, heavy metal toxicity threshold is the highest permissible content in the soil （total or bioavailable concentration） that does not pose any phytotoxic effects or heavy metals in the edible parts of the crops does not exceed food hygiene standards. Factors affecting the thresholds of dietary toxicity of heavy metal in soil-crop system include： soil type which includes soil pH, organic matter content, clay mineral and other soil chemical and biochemical properties; and crop species or cultivars regulated by genetic basis for heavy metal transport and accumulation in plants. In addition, the interactions of soil-plant root-microbes play important roles in regulating heavy metal movement from soil to the edible parts of crops. Agronomic practices such as fertilizer and water managements as well as crop rotation system can affect bioavailability and crop accumulation of heavy metals, thus influencing the thresholds for assessing dietary toxicity of heavy metals in the food chain. This paper reviews the phytotoxic effects and bioaccumulation of heavy metals in vegetables and food crops and assesses soil heavy metal thresholds for potential dietary toxicity. 相似文献
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Bucket foundations[1 ,2]are a relatively newtype offoundation usedto support offshore structures .Each bucketfoundation consists of a thin cylindrical steel shell ,cappedwithalid of steel or concrete .Thefoundationcan penetrateinto sea floor when pumping … 相似文献
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文章对哈尔滨地区的粉质粘土进行了冻结过程的水分迁移试验,考察了含水率、冻结温度及干密度在封闭系统的条件下对粉质粘土中水分迁移的影响。结果表明,控制含水率和干密度相同,顶板的冻结温度越高,水分迁移量越大,顶板冻结温度为-3℃的水分迁移量较冻结温度为-9℃的水分迁移量大;控制顶板冻结温度和干密度相同,初始含水率大的试样,水分迁移量大;控制顶板冻结温度和含水率相同,水分迁移量随干密度的增加而减小。 相似文献
8.
ZHANG Ming-kui ZHENG Shun-an 《浙江大学学报(A卷英文版)》2007,8(11):1808-1815
Soils can often be contaminated simultaneously by more than one heavy metal. The sorption-desorption behavior of a metal in a soil will be affected by the presence of other metals. Therefore, selective retention and competitive adsorption of the soils to heavy metals can affect their availability and movement through the soils. In this study, the simultaneous competitive adsorption of four heavy metals (Cd, Cu, Hg, and Pb) on ten agricultural soils collected from the Changjiang and Zhujiang deltas, China was assessed. The results showed that the competition affected the behavior of heavy metal cations in such a way that the soils adsorbed less Cd and Hg, and more Pb and Cu with increasing total metal concentrations, regardless of the molar concen- tration applied. As the applied concentrations increased, Pb and Cu adsorption increased, while Cd and Hg adsorption decreased. The adsorption sequence most found was Pb>Cu>Hg>Cd. The maximum adsorption capacity for the heavy metal cations was calculated, and affected markedly by soil properties. The results suggest that Hg and Cd have higher mobility associated to the lower adsorption and that Pb and Cu present the opposite behavior. Significant correlations were found between the maximum adsorption capacity of the metals and pH value and exchangeable acid, suggesting that soil pH and exchangeable acid were key factors controlling the solubility and mobility of the metals in the agricultural soils. 相似文献
9.
Numerical Analysis of Soil Plug Inside Suction Foundations During Suction Penetration by Discrete Element Method 总被引：2，自引：1，他引：2
The phenomenon of the soil plug usually rising inside the suction foundations during suction penetration was quantitatively described and predicted. The formation process of the soil plug was simulated and calculated by DEM （discrete element method） model. The seepage flow, the self-weight of soil, the friction on the chamber wall as well as the suction inside the chamber are considered as the main external forces in the process. The results are compared with a set of laboratory model tests performed by using three soil types （sand, silty clay and clay） in the Bohai Sea area. The heights of soil plug from numerical estimations are lower than those from model test results, mainly because the suction pressure and friction resistance are applied in an ideal way under the numerical simulation. 相似文献
10.
Thermal conductivity of soils with heavy metals concentration from the Niger Delta region of Nigeria
Akinyemi OD Olowofela JA Akinlade OO Akande OO 《Journal of Zhejiang University. Science. B》2006,7(8):615-618
INTRODUCTION Knowledge of soil thermal properties is an im- portant factor in understanding mass and energy ex- change processes in the soil-atmosphere system. The chemical composition of the soils will therefore in- directly relate to their thermal conductivities. Ac- cording to Usowicz (1993), this knowledge can also help in controlling the thermal-moisture regime of soils. Soil properties often correlated with metal ad- sorption include soil pH (Christensen, 1984; Harter, 1983), soil … 相似文献
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对莆田市郊区蔬菜地土壤中pH值和有机质、Pb、Cd、Cr、Ni、Cu、Zn的含量进行了测定,结果表明,莆田市郊区蔬菜地土壤重金属含量在地区内及地区间的差异较大,Ni、Cu平均含量以新度镇较高,Pb、Cd平均含量以镇海、拱辰办较高,Cr、Zn平均含量以黄石镇较高,各地区重金属元素受地区影响显著性排序为Zn>Cr>Cd>Pb>Cu>Ni。相关性分析表明,莆田市郊区蔬菜地土壤中部分重金属元素以及有机质间存在一定的相关性。所有样本中6种重金属均没有超过GB15618-1995二级标准值,但与福建省水稻土背景值比较,均有不同程度超背景值现象,其中Cr、Cu、Ni超背景值率较高,富集较明显。 相似文献
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为探究无支撑多级支护结构的不同设计参数对基坑变形的影响,以一个无支撑两级支护的粉质黏土深基坑为例,利用FLAC3D软件建立数值模型,并基于正交试验通过极差、方差分析,就两级支护间距、开挖比以及两级支护结构长度对支护结构位移的影响进行研究。主要结论如下:采用无支撑两级支护结构的粉质黏土深基坑,两级支护结构的顶部最大位移受两级支护间距和开挖比影响的敏感度较高两级支护结构位移之间存在“叠加作用”、“牵引作用”的相互影响,但当两级支护间距不小于总开挖深度的0.5倍时,相互影响不显著当两级支护间距不小于总开挖深度的0.5倍,且开挖比为0.8~1.3时,两级支护结构的顶部最大位移比较接近,且不超过规范的一级基坑下限控制值,处于最合理的工作状态。 相似文献
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对宿州市近郊农田土壤中4种重金属元素Cu、Pb、Zn和As的含量、空间分布及来源状况进行了分析,并采用综合指数法对其农田土壤重金属污染水平进行了评价。结果发现:宿州市近郊农田土壤中Cu、Pb、Zn的平均含量低于安徽省土壤背景值,As高于背景值;Pb和Zn的含量空间分布受交通污染源的影响,Cu与生活垃圾及废弃物的排放有关,As则来源于农药产品的使用;近郊农田土壤重金属为轻污染水平,以As污染最严重。 相似文献
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河南大学校园土壤中主要重金属状况及其评价 总被引：1，自引：0，他引：1
以河南大学校园的绿地、教学和生活区土壤中重金属和微量元素为研究对象,分析并评价了校园土壤中全量铜、锌、镍、铅、铬和有效态铜、锌、铁、锰、硼、钼的分布状况,污染程度及丰缺水平.结果发现:校园土壤除了锌污染严重之外,几乎没有重金属污染或重金属污染程度较低,并且重金属含量在绿地、教学和生活区存在一定的差异,表现出一定的随土地利用方式不同而变化的特点. 相似文献
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以临沂市区公路沿线土壤的重金属为研究对象,采集了05cm和205cm和2025cm处的表层土壤,采用电感耦合等离子原子发射光谱仪测定其中的Cd、Cu、Pb和Zn 4种重金属的含量,以查明当前公路两侧土壤受交通工具引起的重金属污染情况.研究结果表明,沿公路线的土壤中存在较严重的污染,主要是Pb和Cd出现中度乃至重度污染,同时也说明公路交通也会对其沿线土壤重金属污染产生较大影响. 相似文献
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化学淋洗法修复重金属污染土壤效果研究 总被引：6，自引：0，他引：6
在国内外相关研究的基础上,文章研究化学淋洗修复技术在重金属污染土壤修复方面的运用．用浓酸消解土样并用火焰原子吸收法测定土壤中重金属含量,选用土壤柱作淋洗实验,分析去离子水和EDTA溶液两种淋洗剂对Cu、Zn、Pb、Cd四种重金属的淋洗效率,并对化学淋洗修复效果进行比较． 相似文献
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靳璐 《淮北职业技术学院学报》2011,10(2):138-140
不同浓度重金属溶液会对草履虫的种群密度产生影响：低浓度的重金属对草履虫的生长起促进作用,当cd＋＋的浓度为0.10mg/L左右时,它对草履虫的负面影响最小,实验第一天不同重金属浓度下草履虫最大的种群密度为27,第二天不同条件下草履虫最大的种群密度为119.5;而高浓度的重金属对草履虫的生长有明显的抑制作用,即当cd＋＋的浓度大于0.25mg/L时,重金属的抑制作用随浓度的增加而增加。此项研究对于环境监测及水污染防治等均有重要意义。 相似文献