Trace element availability and plant growth in a mine-spill contaminated soil under assisted natural remediation I. Soils

We evaluated the effects of different amendments and/or a plant cover on reclamation of a trace element contaminated soil. Seven treatments were established: four organic (leonardite (LEO), litter (LIT), municipal waste compost (MWC), biosolid compost (BC)), one inorganic (sugar beet lime (SL)) and two controls (control without amendment but with Agrostis (CTRP) and control without amendment and without Agrostis (CTR)). Results showed that total organic C was significantly higher in organic treatments in all samplings. Water-soluble C was lower in CTR compared to other treatments, but no significant differences were observed between organic treatments and SL and CTR. SL, BC and MWC treatments increased soil pH and reduced 0.01 M CaCl2-extractable Cd, Cu and Zn concentrations more efficiently, especially in the first 2 years. At the end of the experiment 0.01 M CaCl2-extractable trace element concentrations were similar in all treatments. 0.01 M CaCl2-extractable As and Pb were below the detection limit. Addition of amendments showed no clear reduction in 0.05 M EDTA-extractable trace element concentrations and some amendments even increased 0.05 M EDTA-extractable As and Cu with time. Pseudo-total trace element concentrations were higher for As in controls. On the other hand, mean values of Cu and Zn were higher in MWC treatment. BC and SL treatments also showed higher Zn mean concentration than controls. No amendment effect was observed for Cd and Pb.     

Influence of soil properties on trace element availability and plant accumulation in a Mediterranean salt marsh polluted by mining wastes: implications for phytomanagement

The aims of this study were to determine the factors which control metal and As phytoavailability in the different microenvironments (Sand Dunes, Salt Flat, Dry River and Shrubs) present at a Mediterranean salt marsh polluted by mining wastes. We performed a field study following a plot sampling survey. The analyses of soil parameters (pH, electrical conductivity (EC), organic carbon contents, etc.), total metal and As concentrations and their phytoavailability assessed with EDTA were related to each microenvironment and the corresponding plant species uptake. The averages of pH and EC were slightly alkaline (pH ≈ 7.5) and saline (≈ 2.2 to 17.1 dS m⁻¹) respectively. The soil samples from the Salt Flat subzone showed the highest metal concentrations (e.g. 51 mg kg⁻¹ Cd, 11,600 mg kg⁻¹ Pb) while for As, the highest concentrations occurred in the Dry River (380 mg kg⁻¹ As). The total metal and EDTA-extractable concentrations occurred as it follows: Salt Flat > Dry River > Degraded Dunes > Shrubs. In relation to plant metal and As accumulation, the highest root concentrations were obtained in the species from the Salt Flat subzone: ~ 17 mg kg⁻¹ As, ~ 620 mg kg⁻¹ Pb, for both, Juncus maritimus and Arthrocnemum macrostachyum. However the highest metal and As shoot concentrations occurred in species from the Sand Dunes: ~ 23 mg kg⁻¹ As ~ 270 mg kg⁻¹ Pb for Dittrichia viscosa; ~ 23 mg kg⁻¹ As, ~ 390 mg kg⁻¹ Zn for Crucianella maritima. The occurrence of edaphic gradients including salinity and texture determined the vegetation distribution. However, it cannot be concluded that there was a disturbance due to metal(loid)s soil concentrations in terms of vegetation composition except in the Degraded Dunes and Dry River. The higher EDTA-extractable concentrations were coincidental with the most saline soils but this did not result in higher metal(loid)s plant accumulation.     

Oil-contaminated soils under engineering constructions and technology of soil remediation

Oil around buildings is sucked under them. The conditions for accumulation of oil exist under engineering constructions. It is necessary to clean oil-contaminated territory, whether it is free from infrastructure or under engineering constructions. Cleaning technology with hydrocarbon-reducing micro-organisms was tested on the site of a tank farm with contaminated soils. The sorbent with micro-organisms placed at a depth of 40–60?cm below the technical buildings has cleaned the oil from the soil. The micro-organisms assimilate the n-alkanes with C₁₄ chains rather than the C₃₂–C₄₀. The oil is destroyed quicker under the constructions than in the open areas.     

Long-term distribution, mobility and plant availability of compost-derived heavy metals in a landfill covering soil

The application of municipal waste compost (MWC) and other organic materials may serve to enhance soil fertility of earthen materials and mine spoils used in land reclamation activities, particularly in the recovery of degraded areas left by exhausted quarries, mines and landfill sites among others. The long-term distribution, mobility and phytoavailability of heavy metals in such anthropogenic soils were studied by collecting soil samples at different depths over a 10 y chronosequence subsequent to amendment of the top layer of a landfill covering soil with a single dose of mechanically-separated MWC. Amendment resulted in a significant enhancement of the metal loadings in the amended topsoils particularly for Cu, Zn and Pb, which were also the predominant metals in the compost utilised. Although metals were predominantly retained in the compost amended soil horizon, with time their vertical distribution resulted in a moderate enrichment of the underlying mineral horizons, not directly influenced by compost amendment. This enrichment generally resulted from the leaching of soluble organo-metal complexes and subsequent adsorption to mineral horizons. However, in the course of the 10-y experimental period, metal concentrations in the underlying horizons generally returned to background concentrations suggesting a potential loss of metals from the soil system. Analysis of the tissues of plants growing spontaneously on the landfill site suggests that metal phytoavailability was limited and generally species-dependent.     

Trace element differentiation in ferruginous accumulation soil patterns under tropical rainforest of southern Cameroon,the role of climatic change

Regions under tropical rainforest cover, such as central Africa and Brazil are characterised by degradation and dismantling of old ferricrete structures. In southern Cameroon, these processes are relayed by present-day ferruginous accumulation soil facies, situated on the middle and the lower part of hill slopes. These facies become progressively harder towards the surface, containing from bottom to top, mainly kaolinite, kaolinite-goethite and Al-rich goethite-hematite, and are discontinuous to the relictic hematite-dominated ferricrete that exist in the upper part of the hill slope. These features were investigated in terms of geochemical differentiation of trace elements. It appears that, in contrast to the old ferricrete facies, the current ferruginous accumulations are enriched in transitional trace elements (V, Cr, Co, Y, Sc) and Pb, while alkali-earth elements are less differentiated. This recent chemical accumulation is controlled both by intense weathering of the granodiorite bedrock and by mobilisation of elements previously accumulated in the old ferricrete. The observed processes are clearly linked to the present-day humid climate with rising groundwater tables. They slowly replace the old ferricretes formed during Cretaceous time under more seasonal climatic conditions, representing an instructive case of continuos global change.     

列车交通荷载作用下地基土单元体的应力路径

为研究列车交通荷载作用下地基内部动应力特征以及土体单元经历的应力路径,基于2.5维有限元数值方法建立轨道-路堤-地基耦合分析模型,其中轨道在轮轴荷载作用下的弯曲变形用欧拉梁来描述,而列车荷载被简化为作用于轨道上的单个或多个移动轮轴荷载,通过基于半解析的方法推导得到了地基中的动应力解答。剖析列车轮轴荷载作用过程中地基内部土单元体经历的应力路径和其中的主应力轴旋转现象;发现当列车速度低于地基剪切波速时,不同速度的荷载作用下不同地基深度处的土单元应力路径曲线形状都很相似;而当荷载速度增大到接近或者超过地基剪切波速时,土单元应力路径曲线和应力分布均发生很大改变。分析结果为研究交通荷载作用下软土的动力特性及地基长期附加沉降提供了基础。     

Evaluation of the soil biological activity in a remediation soil assay using organic amendments and vegetal cover

The recovery of a degraded soil was assayed in greenhouse conditions by applying organic amendments and revegetation with grasses. Two types of organic residues were used: sewage sludge composted with pruning waste (CPW), at 8.5 and 85 Mg ha(-1) and sewage sludge treated by thermal drying (TD), at 22 and 46 Mg ha(-1). The vegetal cover was established by sowing different herbaceous species commonly used in the revegetation of degraded alkaline soils (100 and 200 Kg of seeds ha(-1)). The chemical soil parameters and enzymatic activities (alkaline phosphatase, urease, and beta-glucosidase) and the vegetal biomass were evaluated. The type of amendment and the doses applied had different effects on the soil characteristics. However sowing dose did not have a significant effect on the parameters analysed. Organic matter was the only soil parameter affected by the interaction between the sowing rate and the amendment dose. The phosphatase and glucosidase activities showed significant correlation with the percentage of N in the leaves and stems, furthermore the phosphate activity was significantly related to the dry weight of leaves and stems.     

Trace element deposition and trends during a ten year period in Finland

The deposition of aluminium, arsenic, cadmium, chromium, copper, iron, lead, manganese, nickel, vanadium and zinc in bulk precipitation was examined at eight background stations in Finland during the last 10 years (1998-2007). The annual deposition was from the lowest values to the highest Cd < As < Cr < Ni < V < Cu and Pb < Mn < Zn < Al < Fe. Most of the elements had a south to north decreasing gradient mainly due to minor domestic emissions in the north, growing distance to the large European source areas and differences in the length of snow-cover period. Element enrichment factors divided the trace elements to the following categories: (1) slightly enriched Cr, Fe and Mn; (2) moderately enriched Cu, Ni and V; and (3) highly enriched As, Cd, Pb and Zn. Trend analysis of annual depositions showed that the established decreasing trend in As and Pb deposition continued during our study period while Cr, Cu and Fe depositions have lately increased. No statistically significant trends were detected for Cd, Mn, Ni, V and Zn during the studied years. Additionally, the measurement uncertainty of trace elements was evaluated for the whole measurement chain.     

湿热气候下浅覆土冻结温度场有限元反演分析

对湿热气候下浅覆土冻结温度场进行了现场实测及有限元反演分析。结果发现:模拟得到的整个截面上的温度场分布和实际的较接近。说明土体参数反分析时等效导热系数取值合理。     

Trace element reference values in tissues from inhabitants of the European Community. II. Examples of strategy adopted and trace element analysis of blood, lymph nodes and cerebrospinal fluid of Italian subjects.

The EURO TERVIHT (Trace Element Reference Values in Human Tissues), recently initiated, aims to establish and compare trace metal reference values in inhabitants from the different EC countries. The project anticipates international cooperation of specialized chemical and toxicological laboratories in Western Europe. In order to overcome the well known and intolerable high fluctuation in published trace metal concentrations in body fluids and tissues, which are mostly due to poor analysis, this paper gives recommendations and strategies for approaching 'background' values measurement practised in the EURO TERVIHT. The focus of the paper is more on quality rather than on quantity of data with particular aspects: (i) well-described protocol for the selection/composition of reference groups (extended epidemiological data plus clinical status); (ii) numerous pre-analytical factors, among which are of paramount importance are ultraclean laboratory air, container material, storage conditions at -20 degrees C; (iii) statistical treatment of the data and the expression of the analytical results (use of refined statistical analysis such as the Lilliefors test to define the type of distribution, normal or log-normal). Results reported here concern the determination of trace elements in whole blood of more than 350 Italian subjects which allowed the proposal of 'reference values' for 12 elements. In lymph nodes and cerebrospinal (CSF) the degree of information acquired is only sufficient to suggest 'indicative' of 'informative' values.     

Influence of zeolite on the availability of radiocaesium in soil to plants.

Plant availability of radiocaesium is usually high immediately after incorporation in a soil. However, for some Swedish soils, e.g, peat soils, a high radiocaesium uptake in plants has also been observed during a second growth period after contamination. For these soils the reduction in the plant availability of the nuclide seems to be a slow process. In the last two years the mineral zeolite has become of interest and has been tested as a caesium binding agent in both animal and in soil-plant systems. The aim of this study was to evaluate the time dependency and the effect of zeolite on the plant availability of radiocaesium in a peat soil-plant system. The pot experiments designed for this purpose were carried out in a climate chamber, using winter wheat as the test crop. A significant reduction of the uptake of 134Cs was obtained in wheat when increasing amounts of zeolite were added. This reduction in plant uptake, up to a factor of 8, might depend on two factors. One is that zeolite has reduced the activity concentration of radiocaesium in the soil solution available to the plant roots. The other is that the potassium added with the natural zeolite increased the degree of dilution of caesium in the soil solution. Also, increasing equilibration time for caesium in soil before sowing brought about an effective reduction in the caesium uptake.     

Phytotoxicity and uptake of nitroglycerin in a natural sandy loam soil

Nitroglycerin (NG) is widely used for the production of explosives and solid propellants, and is a soil contaminant of concern at some military training ranges. NG phytotoxicity data reported in the literature cannot be applied directly to development of ecotoxicological benchmarks for plant exposures in soil because they were determined in studies using hydroponic media, cell cultures, and transgenic plants. Toxicities of NG in the present studies were evaluated for alfalfa (Medicago sativa), barnyard grass (Echinochloa crusgalli), and ryegrass (Lolium perenne) exposed to NG in Sassafras sandy loam soil. Uptake and degradation of NG were also evaluated in ryegrass. The median effective concentration values for shoot growth ranged from 40 to 231 mg kg^− 1 in studies with NG freshly amended in soil, and from 23 to 185 mg kg^− 1 in studies with NG weathered-and-aged in soil. Weathering-and-aging NG in soil did not significantly affect the toxicity based on 95% confidence intervals for either seedling emergence or plant growth endpoints. Uptake studies revealed that NG was not accumulated in ryegrass but was transformed into dinitroglycerin in the soil and roots, and was subsequently translocated into the ryegrass shoots. The highest bioconcentration factors for dinitroglycerin of 685 and 40 were determined for roots and shoots, respectively. Results of these studies will improve our understanding of toxicity and bioconcentration of NG in terrestrial plants and will contribute to ecological risk assessment of NG-contaminated sites.     

Electrodialytic remediation of CCA-treated waste wood in a 2 m(3) pilot plant

Waste wood that has been treated with chromated-copper-arsenate (CCA) poses a potential environmental problem due to the content of copper, chromium and arsenic. A pilot plant for electrodialytic remediation of up to 2 m(3) wood has been designed and tested and the results are presented here. Several process parameters were investigated, and it was found that the use of collecting units and soaking of the wood prior to the electrodialytic process had a positive influence on the remediation process. There was a tendency towards higher removal of CCA from wood chips <2 cm, compared to larger wood size fractions. The best remediation efficiency was obtained in an experiment with an electrode distance of 60 cm, and 100 kg wood chips. In this experiment 87% copper, 81% chromium and >95% arsenic were removed. One other experiment was also analysed for arsenic. In this experiment the distance between the working electrodes was 1.5 m and here 95% As was removed. The results showed that arsenic may be the easiest removable of the copper, chromium and arsenic investigated here. This is very encouraging since arsenic is the CCA components of most environmental concern.     

植物纤维增强砌块砌体轴心受压试验研究与有限元分析

通过植物纤维增强砌块砌体轴心抗压强度试验,研究了其破坏特征、抗压强度、应力-应变关系、弹性模量及泊松比。基于试验研究,运用有限元方法,研究其承载力水平、裂缝发展和应力-应变分布及位移变形情况,特别是其微观层面的裂缝演化机制,从理论上深入分析其破坏机理,阐明了砌体各组成材料间的相互作用及其影响、受力薄弱区,得出了横向拉应力不足和弹性地基作用是其破坏根本原因等许多有益的结论。研究成果为植物纤维增强砌块的推广应用以及相关规程的编制、修改提供依据,为类似的试验研究提供参考。     

自然光作为设计元素的设计理念和手法

对路易斯.康的光论进行翻译研究,以康的达卡国会会议堂为例进行分析,总结了自然光作为设计元素的设计理念和手法,提出自然光是重要的建筑设计元素,运用自然光营造空间属性是空间设计的关键。     

某热轧轧钢厂房地下室有限元分析

截取热轧厂房地下室中的一部分,采用SOFISTIK有限元软件对其进行三维计算分析。计算中将桩简化为线弹性的弹簧单元作为地下室承载体系,分析了不同部位桩反力以及不均匀沉降的分布情况。根据计算结果,对地下室顶、底板以及侧壁的受力状况进行了分析,并与常规计算进行对比,提出了合理建议。     

Stresses and displacements in the soil under a circular foundation

Conclusions 1. For the first time, the methods of the theory of elasticity and the theory of limiting equilibrium have been used for establishing the curvilinear nature of the relations S=f(P), which corresponds to the nature of this relation observed in tests with trial loads.2. For all cases of embedment of the plate and for loads substantially smaller than the limiting loads, the contact pressure diagrams are similar to those obtained by the theory of elasticity, but do not exhibit any special characteristics under the edges. This agrees with the results of experimental investigations carried out in order to determine the contact pressures.3. The plate displacements, for all other conditions being equal, and also for loads exceeding 0.3 MPa, depend substantially on the relative embedment of the plate in the soil or on the soil cohesion.4. For practical analyses, the relation S=f(P) obtained by solution of the elastoplastic problem can be approximated by a hyperbola.Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 38–40, September–October, 1974.     

某电厂板仓钢支架结构有限元分析与验算

对某电厂钢板仓钢支架结构进行有限元分析.依据相关规范对支架结构进行验算.对支架结构提出了设计修改方案.有限元分析和计算表明,改进后的支架结构强度、刚度、稳定性符合要求.     

Potential of zero-valent iron in remediation of Cd(II) contaminated soil: From laboratory experiment,mechanism study to field application

This study investigates the potential of ZVI on Cd(II) contaminated soil remediation through laboratory experiment, mechanism study and field application. The results show that the dosage of ZVI, the initial concentration level and the reaction time have significant impacts on Cd(II) adsorption and about 88% of aqueous Cd(II) can be removed from soils. The ZVI is observed to promote the increase of Cd(II) residual fraction in Cd(II) contaminated soils according to the sequential extraction procedure (SEP) results. Regression of the laboratory experimental data based on the Langmuir isotherm equation shows the adsorption capacity can reach 34.7 mg/g. Such a high value is attributed to physical and chemical adsorption, which is proved by X-ray diffraction patterns (XRD), scanning electron microscope images (SEM), and Brunner-Emmet-Teller & Barret–Joyner–Halenda (BET-BJH) analysis. The field application shows that the ZVI can reduce the Cd(II) content in soils and brown rice by 51% and alleviate soil acidification, resulting in a 9.4% increase in rice yields.     

Multivariate outlier detection and remediation in geochemical databases.

In this study, outliers are classified into three types: (1) range outliers; (2) spatial outliers; and (3) relationship outliers, defined as observations that fall outside of the values expected from correlation within the dataset. The multivariate methods of principal component analysis (PCA), multiple regression analysis (MRA) and an autoassociation neural network (AutoNN) method are applied to a dataset comprising 203 samples of rare earth element (REE) concentrations in soils of Jamaica which shows the expected good correlations between the elements. PCA is shown to be effective in detection of high value range outliers, while AutoNN and MRA are effective in detection of relationship outliers. A backpropagation neural network was used to predict the 'expected values' of the outliers. Four obvious relationship outliers with unexpected low Sm concentrations were selected as an example for remediation. The predicted Sm values were confirmed on remeasurement. Neural network methods, with the advantages of being model-free and effective in solving non-linear relationship problems, appear to provide an automated and effective way for the quality control of environmental databases.