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1.

Purpose

Geogenic soil enrichment and anthropogenic pollution by potentially toxic trace elements (PTEs) are two processes acting together. Although it is often difficult, it is necessary to separate the two processes for risk assessment and understanding the environmental implications. The aim of this study was to analyse the soil concentrations of various PTEs in a southern Italy area in order to: (1) determine their different correlation structure to isolate sources of variation acting at different spatial scales and (2) to define potential anomalies based on the correlation structure.

Materials and methods

In the urban and peri-urban area of Cosenza-Rende, 149 topsoil samples were collected (0.10 m) and analysed for different elements by X-ray fluorescence spectrometry. Principal component analysis and factorial kriging analysis were used to map the spatial distribution of PTEs in topsoil and to identify the main factors influencing their spatial variability.

Results and discussion

Two groups of PTEs were identified: the first group included As, Pb and Zn; and the second one Al, Co, Cr, Fe, La, Nb, Ni, Ti and V. The first group was related to anthropogenic causes, while the second one was more related to parent rock composition. The regionalized factors at different scales of variability allowed to aggregate and summarize the joint variability in the PTEs and consider the probable causes of soil pollution.

Conclusions

The study allowed analysing and quantifying the sources (environmental or anthropogenic) of variation of PTEs acting at different spatial scale and defining the spatial anomalies based on the correlation structure associated at the different spatial scales.  相似文献   

2.

Purpose

Metal mining is the main cause of soil contamination caused by heavy metals. Mine tailings and minespoils generally offer hostile environments for plant growth due to their low nutrient availability, low organic matter content, and high trace metal content. This study was carried out with the aim of characterizing the soils that have developed on the tailings from an abandoned lead and zinc mine in Galicia (NW Spain) and determining the soil factors that limit revegetation.

Materials and methods

We selected three zones: (a) the minespoils, (b) in the mining area, and (c) the settling pond, where the sludge from the flotation process was deposited. A control soil was also sampled outside of the mining area. We analyzed the physicochemical properties and metal levels in the mine spoil and soil samples we collected.

Results and discussion

The results indicate that the main physical limitations of minesoils are their low effective depth, high porosity and stoniness, while the main chemical limitations are low organic matter content and low CEC and an imbalance between exchangeable cations. These minesoils are strongly affected by high Zn and Pb levels which hinder revegetation.

Conclusions

As high concentrations of toxic trace elements and a high pH are important factors in limiting the plant growth, the restoration procedure must overcome the oxidation processes by adding organic amendments that also contribute towards fixing heavy metals or by implanting spontaneous vegetation adapted to the mine conditions, such as common broom (Cytisus scoparius) or white birch (Betula celtiberica).  相似文献   

3.

Goal, Scope and Background

In the nineteen nineties most European countries issued legislation on soil protection, including soil contamination. In the case of a presumed contamination, soil investigation mostly follows a stepwise approach starting with a preliminary investigation, then an in-depth investigation and, finally, remediation. Soil clean-up standards are often foreseen as trigger criteria to determine the need for an in-depth soil investigation or for remediation. There are however large differences in soil clean-up standards. This is partly because of the different roles of soil clean-up standards in each legislative framework and partly because of differences in the soil clean-up standard (SCS) derivation procedures. Despites these differences there are large similarities in the concepts of the derivation procedures for clean-up standards. A better understanding of the differences in clean-up standards is needed. In order to clarify the variation, the background of the clean-up standards for a selected number of countries was investigated. The objective of this paper is to investigate the underlying reason why country-wide generic soil and groundwater clean-up standards of eight trace elements (cadmium, chromium (III), copper, mercury, lead, nickel, zinc and arsenic) differ between the selected countries.

Main Features

To avoid misinterpretation of the differences in application of the clean-up standards, a short overview of the legislative role of clean-up standards is given first. Differences in model concepts and parameter values are discussed, followed by a comparison of the generic soil and groundwater clean-up standards for trace elements and a discussion on the sources of variation. The influence of the use of ecotoxicological criteria and data for the derivation of soil clean-up standards will be discussed in more detail. Selected countries were Canada, the Flemish Region (Belgium), France, Germany, Great-Britain, the Netherlands, Norway, Sweden, Switzerland and United States of America (USA).

Results and Discussion

When soil clean-up standards for eight trace elements (cadmium, chromium (III), copper, mercury, lead, nickel, zinc and arsenic) were compared between the selected countries differences of more than a factor 1000 arose. Notwithstanding the use of similar derivation procedures, differences were caused by the use of different software models with their specific input data, boundary conditions and applied protection criteria for humans and the ecology. Ecotoxicological criteria tend to lower the soil clean-up standard for the selected trace elements.

Conclusions

In the countries that are included in this study, clean-up standards are used is different ways, this is for the determination of the necessity for remediation or for the need for further soil investigation. This paper shows a wide variation in the clean-up standards, which has further implication on the decision for remediation or further investigation and, hence, the financial costs of soil management. All the clean-up standards have as primary goal the protection of human health. A number of countries also include the protection of the ecological function of the soil. Differences in selected software model, (standard) parameters values, selected human toxicological and ecotoxicological criteria, are reason for a substantial variation in the clean-up standards for trace elements.

Recommendations and Perspective

. Is this variation justified? The derivation of soil clean-up standards involves - besides scientific elements - political elements, like differentiation in landuse types (agricultural, residential, recreational, industrial), receptor at risk or protection level. It is obvious that harmonization of these elements will be complicated. However, a European action programme, like the thematic strategy for soil protection, could initiate this process of harmonization. Nevertheless, soil-clean-up standards could never be uniform over the whole of Europe because they include country specific elements (geographical, ethnological) and political decisions.  相似文献   

4.

Purpose

Discharge of untreated domestic and industrial waste in many European rivers resulted in low oxygen concentrations and contamination with trace metals, often concentrated in sediments. Under these anoxic conditions, the formation of insoluble metal sulfides is known to reduce metal availability. Nowadays, implementation of waste water treatment plants results in increasing surface water oxygen concentrations. Under these conditions, sediments can be turned from a trace metal sink into a trace metal source.

Materials and methods

In an ex situ experiment with metal contaminated sediment, we investigated the effect of surface water aeration on sediment metal sulfide (acid volatile sulfides (AVS)) concentrations and sediment metal release to the surface water. These results were compared with long-term field data, where surface water oxygen and metal concentrations, before and after the implementation of a waste water treatment plant, were compared.

Results and discussion

Aeration of surface water in the experimental setup resulted in a decrease of sediment AVS concentrations due to sulfide oxidation. Metals, known to precipitate with these sulfides, became more mobile and increasing dissolved metal (arsenic (As), cadmium (Cd), copper (Cu)) concentrations in the surface water were observed. Contrary to As, Cd, or Cu, manganese (Mn) surface water concentrations decreased in the aerated treatment. Mn ions will precipitate and accumulate in the sediment as Mn oxides under the oxic conditions. Field data, however, demonstrated a decrease of all total metal surface water concentrations with increasing oxygen concentrations following the implementation of the waste water treatment plant.

Conclusions

The gradual decrease in surface water metal concentrations in the river before the treatment started and the removal of metals in the waste water treatment process could not be countered by an increase in metal flux from the sediment as observed in the experiment.  相似文献   

5.

Purpose

This study aimed at investigating correlations between heavy metal concentrations in mosses and modelled deposition values as well as other site-specific and regional characteristics to determine which factors primarily affect cadmium, lead and mercury concentrations in mosses. The resulting relationships could potentially be used to enhance the spatial resolution of heavy metal deposition maps across Europe.

Materials and methods

Modelled heavy metal deposition data and data on the concentration of heavy metals in naturally growing mosses were integrated into a geographic information system and analysed by means of bivariate rank correlation analysis and multivariate decision trees. Modelled deposition data were validated annually with deposition measurements at up to 63 EMEP measurement stations within the European Monitoring and Evaluation Programme (EMEP), and mosses were collected at up to 7,000 sites at 5-year intervals between 1990 and 2005.

Results and discussion

Moderate to high correlations were found between cadmium and lead concentrations in mosses and modelled atmospheric deposition of these metals: Spearman rank correlation coefficients were between 0.62 and 0.67, and 0.67 and 0.73 for cadmium and lead, respectively (p?<?0.001). Multivariate decision tree analyses showed that cadmium and lead concentrations in mosses were primarily determined by the atmospheric deposition of these metals, followed by emissions of the metals. Low to very low correlations were observed between mercury concentrations in mosses and modelled atmospheric deposition of mercury. According to the multivariate analyses, spatial variations of the mercury concentration in mosses was primarily associated with the sampled moss species and not with the modelled deposition, but regional differences in the atmospheric chemistry of mercury and corresponding interactions with the moss may also be involved.

Conclusions

At least for cadmium and lead, concentrations in mosses are a valuable tool in determining and mapping the spatial variation in atmospheric deposition across Europe at a high spatial resolution. For mercury, more studies are needed to elucidate interactions of different chemical species with the moss.  相似文献   

6.

Purpose

Can geochemical characteristics indicate the human impact on soil formation (technosolisation) for urban and suburban soils? This question is assessed for the city of Marrakech located in one of the main agricultural areas of Morocco and characterized by a very rapid rate of expansion. The aim of this work is to assess geochemical properties of surface horizons of urban and suburban soils and to compare them with land use types.

Materials and methods

Fifty-eight surface soil samples were collected in different sectors of the city with different land use histories. As land use can be defined as the human use of land, these sampling sites were selected according to the current human activity (e.g., residential districts, agriculture, market-gardening, traditional, or industrial activities) and according to the superposition of the land use over time. All samples were air-dried, disaggregated, homogenized, and then sieved through a 2-mm mesh. Major elements and trace metals were measured in the soil using X-ray fluorescence spectroscopy. For technical limits, Cd was measured using atomic adsorption spectrometry.

Results and discussion

Urban and suburban soils of Marrakech present generally similar geochemical compositions for many elements. Siliceous (SiO2) compounds related to the parent material are dominant in these soils. However, the significant concentrations of P2O5 and CaO, measured in some of the urban soils studied, can be attributed to anthropogenic inputs of phosphorus (P) and technic materials, mainly building materials composed of cement and gypsum (plaster). Soils collected from agricultural areas irrigated with urban wastewater and soils developed on rubbish dumps are the most contaminated by metals (e.g., Cu, Zn, and Pb). Therefore, the distribution of major and trace elements in soils underlines the considerable impact of urban land uses.

Conclusions

Human activities determine the type of land use, impact the urban environment, and cause a wide spatial diversity of soil quality. The urban and suburban soils of Marrakech contain similar major element distributions except for strongly anthropised soils (soils developed on rubbish dumps and agricultural soils irrigated with urban wastewater). Unlike major elements, trace elements present systematically significantly higher concentrations in urban soils than those measured in control soils. In these conditions, the highest concentrations exceed international clean-up standards and are correlated with land use type. Phosphorus, Ca, and several heavy metals are proposed as indicators of human impacts on soil characteristics in urban and suburban environments.  相似文献   

7.
The concentrations of trace and non-trace elements were determined in blood and fibers of alpacas (Vicugna pacos) from a north Italian area, as well as in their pasture forages. This is the first investigation regarding this species in Italy, and the first considering alpaca’s fiber as bioindicator worldwide. Metal contents in blood were in the decreasing order: copper?>?zinc?>?aluminum?>?selenium?>?lead?>?nickel?>?manganese?>?chromium?>?arsenic and cadmium, while in fiber, metal levels were in the following order: aluminum?>?zinc?>?copper?>?manganese?>?chromium?>?nickel?>?selenium?>?lead?>?arsenic and cadmium. Antimony, beryllium, mercury, tin, and thallium were below the limit of quantification (0.010 mg kg?1). The analysis of the alpacas’ forage confirmed the same trend found in fiber, suggesting that metal bioaccumulation was affected by diet. These preliminary results have shown that all the trace elements studied bioaccumulated to a greater extent in the fibers of the alpaca than in the blood. Accordingly, we may suggest that alpaca fibers could be used for monitoring exposure especially to non-essential metals like aluminum, cadmium, and lead, and could constitute a suitable non-invasive method for measuring trace and non-trace element exposure in camelids.  相似文献   

8.

Purpose

Mining activities represent a current source of pollution due to the large release of trace elements from mineral particles into the soil, atmosphere, and ecosystems. In active or abandoned metal-mining areas, direct discharge from mining deposits is one of the most common processes of contamination.

Materials and methods

In this work, we calculated the elemental concentrations of plants, edible for cattle, which might contain high values of toxic elements, such as As, Cu, Zn, and W, originated from mining exploitation, especially wolframite. Several species of plants originating from the same contaminated place, close to the mine, were the subject of our study in order to compare the uptake of harmful elements, from the contaminated soils, in the different plants. We have used the energy-dispersive X-ray fluorescence technique to perform the analysis and quantification of the elements present in the collected samples. The quantification was based on the fundamental parameters method for plants and on the WinAxil compare mode using a standard reference material, for soils. Calibration against a series of standard samples has been carried out.

Results and discussion

A comparison between contaminated and control samples, within the same species, was performed. The contamination of the two mining wash sites is assessed by comparing the elemental concentration of several plants in these places. Elemental content in soils was investigated, and a comparison between elemental levels in plants was performed.

Conclusions

High concentrations of tungsten were found near the new wash site. Arsenic was found throughout the area in concentrations many times higher than those recommended by the World Health Organization.  相似文献   

9.

Purpose

Heavy metals in agricultural soils readily enter the food chain when taken up by plants, but there have been few investigations of heavy metal pressure in farming areas with low background concentrations. This study was carried out in a cultivation area of Northeast China that has undergone decades of intensive farming, with the aim of identifying the sources of accumulated heavy metals in agricultural soils using multivariate analysis and geographic information system (GIS).

Materials and methods

In 2011, concentrations of total iron (Fe), manganese (Mn), copper (Cu), nickel (Ni), lead (Pb), zinc (Zn), cadmium (Cd), chromium (Cr) and cobalt (Co), as well as soil pH and organic matter, were measured at 149 sites in arable soils in the study area. The principal component analysis (PCA) was employed to extract hidden subsets from the raw dataset in order to detect possible sources. Metal contents in soils from various croplands were further investigated using analysis of variance. With the Kriging interpolation method, GIS was used to display the PCA results spatially to explore the influence of land use on heavy metal accumulation.

Results and discussion

Most of the studied metals in arable soils of the study area were shown to have low concentrations, except for Cd (0.241 mg?kg?1). According to the results of the PCA analysis, Fe, Mn, Pb, Zn, Cd, and Co formed the first component (PC1) explaining 40.1 % of the total variance. The source of these metals was attributed to farming practices (“anthropogenic” factor). Cu, Ni, and Cr fell into the second component (PC2), heavy metals that derived from parent rock materials (“lithogetic” factor). This component describes 24.6 % of the total variance. Compared to paddy lands, soils in drylands had greater accumulations of all the metals in PC1, which can be explained by a higher rate of phosphorus fertilizer application and a longer farming history.

Conclusions

Owing to the natural low backgrounds, soils in the study area were safe from heavy metal pollution with a contamination risk of Cd the only exception. Multivariate analysis and GIS were effective means in helping to identify the sources of soil metals and addressing the land use influence on soil metals accumulation. This work can support the development of strategy and policies to aid in the prevention of widespread heavy metal contamination in area with characteristics similar to those of the study area.  相似文献   

10.

Purpose

The establishment of geochemical baselines is essential for accurate evaluation of the present state of surface environments. In this study, normalization procedures (NP), which can improve the explanation of the natural variation of elements, were conducted using geochemical common factors (GCF) and soil organic matter (SOM) as normalizers to define the geochemical baselines of soil trace elements.

Materials and methods

Soil samples (n?=?345) were collected in Luhe County, Jiangsu, China, a county with a complex geologic setting and intensive anthropogenic influence. Conservative elements, Al, Ca, Fe, K, Mg, Mn, Na, P, and Ti; trace elements, As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn; and SOM were measured. Normalization procedures were conducted using multiple linear regressions between soil trace elements and SOM and GCFs, acquired from factor analysis of the soil major elements. Normalization procedures using univariate linear regressions between soil trace elements and conservative elements Al, Fe, and Ti were also conducted for comparison.

Results and discussion

Comparison of NPs using GCFs and SOM as normalizers with NPs, which use single conservative elements as normalizers, shows that the former is more accurate than the latter for As, Pb, and Zn and is as accurate for Cd, Cr, Cu, Hg, and Ni, when the most appropriate single conservative element is chosen. Small-scale geochemical baselines in the county are significantly different from regional-scale geochemical baselines for Jiangsu Province, China.

Conclusions

The application of regional-scale geochemical baselines at small scales may lead to estimation errors in determining anomalies and assessing environments. Baselines obtained from the NPs using GCFs and SOM as normalizers are more accurate.  相似文献   

11.

Purpose

In the Panasqueira mine area, Arbutus unedo L. (arbutus tree) grows on soils developed on waste materials and on soils impacted by mining activity. The arbutus berry brandy is considered a product with economic value. The aims of this study were to evaluate the biogeochemical impact of the mining activity on soils and arbutus trees, to assess the possible risks associated with human consumption of the fruits and the derived brandy, and to evaluate the potential of the arbutus tree in phytostabilization.

Materials and methods

Soil samples (10–15 cm deep) developed on waste materials, on schists affected by seepage water or treatment plant effluents and on colluvium-alluvium materials were characterized (fraction <2 mm) for pH, particle size distribution, organic carbon (Corg), cation exchange capacity (CEC) and NPK by classical methodologies. Plant (A. unedo) samples (roots, leaves and twigs, and fruits) were collected at the same sites as the sampled soils, washed with tap and distilled water and dried at 40 °C. The elements’ concentrations in soils (total fraction—four-acid digestion and available fraction—diethylenetriaminepentaacetic acid extraction), plants (ashing followed by acid digestion) and brandy samples produced with fruits collected on contaminated and non-contaminated sites were determined by inductively coupled plasma atomic emission spectroscopy.

Results and discussion

The soils are mainly acid, silty loam, with variable values for Corg, CEC and NPK. They are contaminated with As (158–7,790 mg/kg), Cd (0.6–79 mg/kg), Cu (51–4,080 mg/kg), W (19–1,450 mg/kg) and Zn (142–12,300 mg/kg). The available fraction of the soils is quite variable between <0.04 and 76 % of the total, depending on the element. Trace elements’ concentrations, in leaves and twigs, are within the normal range for plants, except for Cd and Zn that, in some samples, are above the normal values, but without phytotoxic symptoms. Trace elements’ concentrations in fruits are low. The calculated hazard quotient for all trace elements in arbutus berry was <0.1. In the brandy, elemental concentrations are within the legal standards, except for Pb, whose higher concentrations may result from distillery equipment.

Conclusions

According to the EC 466/2001 legislation and with a hazard quotient of <1, the arbutus berry consumption does not constitute health risks for humans. The fruits can be used to produce local brandy. The concentration of copper in brandy is within the range established by the Portuguese legislation. Arbutus unedo can be used in the phytostabilization programs in the Panasqueira area, for it is a pioneer species and a non-accumulator of trace elements.  相似文献   

12.

Purpose

Urban allotment gardens (UAGs) are expanding worldwide, especially in large cities. Environmental pressures (direct and diffuse pollution, gardener practice, geogenic contamination) often result in the accumulation of potentially harmful trace elements in garden soils. The objectives of this study were to assess the spatial variability of trace element distribution in UAGs from city, garden, and plot scale in four European cities; to provide a baseline understanding and identify abnormal values under environmental pressures; and to evaluate the potential of portable X-ray fluorescence screening as a useful tool in soil management.

Materials and methods

The four cities (Ayr and Greenock (Scotland), Lisbon (Portugal), Nantes (France)) provided a wide range of environmental pressures on soils. The locations of the 14 allotment gardens were identified in consultation with the local municipality in each city to reflect various land uses or according to previous evaluation of soil quality. Soil sampling was carried out in 66 plots in total, from which 3 datasets were produced: (i) basic soil properties and trace element concentrations from a composite sample of topsoil for each plot (trace elements quantified by inductively coupled plasma–optical emission spectrometry/mass spectrometry (ICP-OES/MS) or using in-lab portable X-ray fluorescence (PXRF); (ii) in situ PXRF measurement on composite samples (263 plots in Nantes); and (iii) composite samples from 32 small areas within 4 plots in one garden of Nantes.

Results and discussion

The results were analyzed to assess the spatial variability of soil properties. At city and garden scale, the variability observed for basic soil properties and major elements is dominated by local geology/parent material (pH, CaCO3, Fe) and gardening practice (OM, CaCO3), which vary between each country. The range of trace element concentrations is similar between each city except for Greenock. Extreme values are observed for Cu, Pb, and Zn reflecting human disruption. In most situations, the trace element contamination was explained through the historical and environmental situations of the site. The PXRF screening method proved useful in providing detailed mapping for hot spot detection or delineation, providing support for soil management at plot and garden scale.

Conclusions

As anticipated, basic soil properties appear to be controlled by the parent material. At plot and garden scale, the trace element variability shows the influence of land use history and background and strong inputs from external factors (e.g., by industrial activity or traffic emission). The PXRF screening method appears to be an efficient solution for soil management as it can be used to discriminate zones which may require restriction on cultivation.
  相似文献   

13.

Purpose

A total of 58 dewatered sludge samples were collected from 58 sewage treatment plants (STPs) geographically located in 31 provincial cities of China; the concentrations of heavy metals and antibiotics were determined to monitor the pollutant levels on a large scale, and the pollutant concentrations in sludge samples from different sources of sewage sludge and different geographical regions were compared.

Materials and methods

All the samples were divided into two portions, one of which was air-dried for determination of heavy metals. The other portion was placed in a brown glass bottle and frozen at ?20 °C for antibiotics analysis. Total heavy metals were digested with aqua regia and determined by atomic absorption spectrophotometry (Varian SpectrAA 220FS and Varian SpectrAA 220Z). The antibiotics were extracted with EDTA-sodium phosphate buffer with acetonitrile/Mg(NO3)2-NH3?H2O, v/v, 3:1 and analysed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) and quantified by the isotope-labelled internal standard method.

Results and discussion

In all the sludge samples, zinc was the most abundant metal followed by copper, with relatively low concentrations of chromium, lead, nickel and cadmium. Only 20 % of samples exceeded the Chinese class A values of heavy metal standards for agricultural use (GJ/T309-2009). Sixteen different antibiotics were detected in all the sludge samples, and fluoroquinolones (FQs) and tetracyclines (TCs) were more abundant than sulfonamides (SAs). Concentrations of ∑FQs, ∑TCs and ∑SAs ranged from 1,569 to 23,825 μg kg?1 (mean 8,274 μg kg?1, dry weight), from 592 to 37,895 μg kg?1 (mean 8,326 μg kg?1, dry weight) and from 20.1 to 117 μg kg?1 (mean 55.4 μg kg?1, dry weight), respectively. Tetracyclines (except chlortetracycline) were significantly correlated with zinc and lead. No significant regional trends were observed in the concentrations of heavy metals and antibiotics in sludges.

Conclusions

Heavy metal concentrations are not the major factor restricting domestic and mixed flow sludge application, but the antibiotic concentrations in sludges are problematic; regulation of antibiotic use and establishment of standards to ensure safe handling of sludges are needed.  相似文献   

14.

Purpose

Electromagnetic induction based metal detectors are commonly used in landmine clearance operations. Their performance can be seriously deteriorated by magnetic properties of the soil in which the landmines are buried.

Materials and methods

Soil magnetic parameters were studied at three locations in Southern Mozambique where soils had caused severe problems during former landmine clearance campaigns. Field work comprised a geological and pedological survey of soils and the parent rock materials. Soil and rock samples were analyzed to determine pedological standard parameters and magnetic susceptibility. Geochemical analysis, scanning electron microscopy, and thermomagnetic analysis helped to clarify the mineral composition and to specify the origin and properties of the magnetic minerals. The spatial distribution of the topsoil magnetic susceptibility was investigated in the field and characterized using geostatistical analyses.

Results and discussion

Despite different degrees of weathering of the investigated soils, their magnetic mineral composition is dominated by lithogenic (Ti-) magnetites. Moreover, there are clues for the pedogenic neoformation of ultrafine-grained ferrimagnetic minerals in two of the three topsoils. The deterioration of metal detector performance at the sites results from the high frequency dependence of magnetic susceptibility at two locations and from the distinct spatial variability of topsoil magnetic susceptibility at all locations.

Conclusions

To assess soil effects on the performance of modern metal detectors the investigations of frequency-dependent susceptibility and of spatial susceptibility distribution are the most meaningful tools. Summarizing, the topsoil magnetic properties of the investigated sites are predominantly influenced by their parent material and to a minor degree by pedogenic neoformation.  相似文献   

15.

Purpose

The geochemical compositions of sediments from three sectors in Trincomalee Bay (Koddiyar Bay, Thambalagam Bay and the Inner Harbour) in Sri Lanka were examined to determine fluvial and marine contributions and the effects of sorting and heavy mineral concentration. The present environmental status of the bay was also assessed.

Materials and methods

Forty-nine sediment samples were collected from Trincomalee Bay and analysed by X-ray fluorescence, yielding data for the major elements and 17 trace elements. Mean grain size and sorting were also measured. Data were compared with the compositions of sediments from the lower Mahaweli River, which supplies most of the clastic detritus to Trincomalee Bay.

Results and discussion

Sediments in the three sectors differ significantly in chemical composition, according to position relative to the Mahaweli River delta source, depositional environment, heavy mineral concentration and marine influences. According to accepted sediment quality guidelines, some As contamination may have occurred in the Inner Harbour and Thambalagam Bay and Cr contamination in all three sectors.

Conclusions

Proximal Koddiyar Bay sediments compare closely with Mahaweli River bedload. Although the clastic component in the more distal Thambalagam Bay and the Inner Harbour is also derived from the Mahaweli River, compositions are modified significantly by marine contributions. High concentrations of elements including Ti, Zr, Ce, Nb and Y in NW Koddiyar Bay are consistent with heavy mineral concentration by winnowing in high-energy zones. Some decoupling of Fe–Ti- and Zr-bearing heavy mineral assemblages may occur within the bay. Al-normalized metal enrichment factors and contour maps show that apparent contamination by As and Cr is spurious and is caused by locally high background levels from Mahaweli River detritus. This illustrates the importance of establishing local background levels of elements during environmental studies.  相似文献   

16.

Purpose

Frequent mining activities and higher background values in soil have led to the contamination of the sediments of some rivers in southwest China by several metals and arsenic (As). This study combined multivariate analysis with geochemical approaches to differentiate mining activity from other sources, which may aid to evaluate the effectiveness of reducing mining release.

Materials and methods

Sixteen sediment samples were collected along the Yuan River, China. The total concentrations of lead (Pb), zinc (Zn), copper (Cu), cadmium (Cd), chromium (Cr), mercury (Hg), and As were measured by inductively coupled plasma-atomic emission spectrometer (ICP-AES). The Pb isotopic composition was measured using a thermal ionization mass spectrometer (TIMES). Both geochemical approaches and multivariate statistical analysis were used to identify the sources of these metals. The fractionation of Pb was determined through a Community Bureau of Reference (BCR) sequential extraction procedure to aid the identification of the sources.

Results and discussion

The concentrations and enrichment factors (EFs) of Pb, Zn, Cu, Cd, and As in the middle reach of the river were higher than those at the other sites, indicating anthropogenic sources. The factor analysis (FA) extracted “mining and smelting,” “mixture of anthropogenic and natural,” and “natural” factors. The Pb isotope composition of metal ores was similar (206Pb/207Pb?<?1.190 and 208Pb/206Pb?>?2.023) to that found in the sediments in the middle reach, indicating anthropogenic sources of mining activities. Compared with the narrow ranges of the δ34S ratios in the bedrock (+8.5 to +9.3?‰) and the metal ores (?1.4 to +1.9?‰), the sediment samples presented a relatively wide range of δ34S ratios from ?2.6 to +9.2?‰ with a mean of +2.6?‰, which suggests a mixed composition. The BCR sequential extraction procedure revealed that the proportion of the extractable fraction in the sediments in the middle reach was higher than that in other sites, suggesting anthropogenic sources as the cause of contamination in the study area.

Conclusions

Lead, Zn, Cu, Cd, Cr, Hg, and As are mainly derived from natural materials in the upstream region. In the middle reach, these elements are the result of anthropogenic activities, particularly activities associated with the mining industry. In the downstream region, the origin of these elements is considered to be a mixture of anthropogenic and natural sources. In addition to geochemical approaches and multivariate statistical analysis, the BCR sequential extraction method is an effective procedure for the identification of the anthropogenic sources of sediment-associated metals.  相似文献   

17.

Purpose

This study addresses the feasibility of a flotation technique, using a lab-scale flotation cell, to simultaneously remove both metals and polyaromatic hydrocarbons (PAHs) from fine sediment fractions (<250 μm) that are potentially contaminated with copper (Cu).

Materials and methods

A multiple flotation process with three consecutive flotation stages was performed on three sediments (13S, 14B, and 24A) with different particle size distributions, Cu and PAH concentrations, and organic matter contents.

Results and discussion

Flotations performed under selected conditions allowed for significant removal of both Cu (61–70 %) and PAHs (75–83 %) with acceptable froth recoveries of approximately 23–29 %. Removal rates for arsenic, lead, and zinc were 48–61, 40–48, and 32–36 %, respectively. Flotation selectivity of Cu was greatly influenced by the contents of fine particles and organic matter of the sediments. The maximum flotation selectivity was obtained for the 53–125-μm size fraction. The high flotation selectivity of Cu (2.5–3.2) and PAHs (3.0–3.6) demonstrated the feasibility of flotation to treat soils or sediments containing both organic and inorganic pollutants.

Conclusions

Overall, the flotation results showed a high selectivity for both Cu and PAHs and demonstrated the feasibility of flotation to treat media contaminated with organic and inorganic contaminants.  相似文献   

18.
The concentrations of the trace elements copper and zinc were determined in field‐collected samples of three ericaceous dwarf shrubs of the genus Vaccinium. The average elemental concentrations were rather regular in the three species. The actual minor element levels of the individual samples showed, however, highly significant interspecific differences in the elemental compositions.

The calculation of the discriminant factor values (i.e. the comparative element ratios for the plant samples and for their substrata) resulted in clear species‐specific patterns in the element utilization. Thus, obvious selectivity was recognized in the uptake of copper and zinc by the three Vaccinium species. Of the species studied, V. myrtillus appeared to be an accumulator of copper in relation to zinc, whereas V. uliginosum showed the most efficient uptake of Zn in relation to Cu, and V. vitis‐idaea showed an intermediate pattern in the minor element utilization.  相似文献   


19.

Background, Aims and Scope

Bioavailability of toxic compounds in soil can be defined as the fraction able to come into contact with biota and to cause toxic effects. The contact toxicity tests may detect the total toxic response of all bioavailable contaminants present in a sample. The objectives of this study were to evaluate the use of microbial contact toxicity tests for cadmium bioavailability assessment and to evaluate the relationship between sorption, soil characteristics and cadmium bioavailability.

Methods

A test soil bacterium,Bacillus cereus, was put in direct contact with the solid sample. Four unpolluted soils were selected to provide solid samples with a variety of physicochemical characteristics. The toxicity and sorption behaviour of cadmium spiked to the soil samples were determined.

Results, Discussion and Conclusions

A significant correlation between contact toxicity test results and partitioning of cadmium in the soil samples (r2= 0.79, p <0.05; n = 26) was found. The results confirm that the bioavailability of cadmium in soil depends on its sorption behaviour. Cadmium sorbed to the cation exchange sites associated with fulvic acids is non-bioavailable in the toxicity test employed in this study. It is concluded that the microbial contact toxicity test is a suitable tool for detecting cadmium bioavailablity in the soils used in this study.

Outlook

The application of microbial contact toxicity tests for bioavailability assessment can be very useful for the risk identification and remediation of soil-associated contaminants.  相似文献   

20.

Purpose

This study aimed to compare the variation on the accumulation and translocation of potentially harmful chemical elements and nutrients (As, Ca, Cu, Fe, K, Mg, Mn, Ni, Pb and Zn) in Cistus ladanifer L. belonging to populations growing in different mine areas from the Portuguese Iberian Pyrite Belt (Brancanes, Caveira, Chança, Lousal, Neves Corvo, São Domingos). These mines are abandoned (except Neves Corvo that is still operating) and have different contamination levels.

Materials and methods

Composite samples of soils (n?=?31), developed on different mine wastes and/or host rock, and C. ladanifer plants (roots and shoots) were collected in the mine areas. Soils were characterized for pH, NPK and organic C, by classical methodologies. Soils (total fraction—four acid digestion, and available fraction—extracted with aqueous solution of diluted organic acids, simulating rizosphere conditions) and plants (ashing followed by acid digestion) elemental concentrations were determined by ICP. Soil–plant transfer and translocation coefficients were calculated. Principal components analysis in both ways, the classical method and a second approach with adaptations used mostly in multivariate statistical processes control data, were done in order to compare the plants populations.

Results and discussion

Soils had large heterogeneity in their characteristics. Caveira, Lousal, Neves Corvo and São Domingos soils showed the highest total concentrations of As, Cu, Pb and Zn. Independently of the mine, available fractions of elements were low. Intra- and inter-population variations in accumulation and translocation of elements were evaluated. Plants were not accumulators of the majority of the analysed elements. Nutrients were mainly translocated from roots to shoots, while trace elements were stored in roots (except in Neves Corvo for As and Pb, and São Domingos for As). Elements concentrations in plant populations from Lousal, Chança and São Domingos did not present much variation. Brancanes soils and plants presented strong differences compared to other areas.

Conclusions

Cistus ladanifer plants are able to survive in mining areas with polymetallic contamination at different elements concentrations in total and available fraction. This species presented variations inter- and intra-populations in accumulation and translocation of chemical elements; however, all studied populations, except Brancanes, can belong to the same population cluster.  相似文献   

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