Distribution Of Trace Elements In Soils Research Articles

Characterization and chemical fractionation of potentially toxic elements in soils of a pre-mining mineralized area; an evaluation of mobility and environmental risk.

The environmental geochemical characterization of mineralized areas prior to mining does not receive adequate attention. This study shows trace element distribution in soils of two unexploited porphyry copper deposits located in Darreh-Zereshk and Ali-Abad in central Iran. The study was carried out using a compositional data analysis (CoDa) approach and combination of multivariate statistics and clustering techniques, which made it possible to identify the geochemical associations representing the different areas of the mineral deposits. The results of the chemical analyses, performed by ICP-MS, revealed high concentrations of those elements typically associated with porphyry deposits (As, Co, Cu, Mo, Ni, Pb, and Zn). The typical zonal pattern with an anomaly of Cu in central parts of the system and the prevalence of epithermal elements (Ag, Cd, Pb, and Zn) toward the peripheral propylitic alteration zone were recognized. The XRD analysis of selected soil samples allowed us to determine the distribution of elements within the different carrier minerals. Afterward, geochemical speciation patterns were investigated by a four-step sequential extraction procedure based on BCR protocol. The residual fraction consisting of primary resistant minerals was found to be the main host for As (73-93.4%), Cr (65.1-79.6%), Cu (54.3-81.4%), Ni (58.9-80.6%), V (75.9-88%), and Zn (56.5-60.5%) in the studied soils. Even though these elements are not readily leachable, their behavior and distribution could be largely affected by the mining operation and consequent changes in the physicochemical properties of the soil. The soluble-exchangeable phase was only less than 15% of the total extractions for all elements, except for Cd. With respect to the mobility factor (MF), Cd was the most mobile element followed by Sb and Pb. The measured risk assessment code (RAC) presented the following risk order: Cd > Sb > Ni > Co > Pb > Cr > As > Zn > Cu > V. This study reveals that the acquisition of pre-mining geo-environmental data of trace elements is very important to establish pre-mining backgrounds and baselines for evaluating post-mining or post-reclamation geochemical signatures.

A study of trace elements in plants of the Polar Urals and Chukotka in the search for metallophyte hyperaccumulators

The present study summarizes the results of investigations of the trace element distribution in soils and their uptake by plants of natural habitats on the ultramafic and acidic rocks of the Polar Urals and Chukotka in the Arctic Russia. Concentrations of Fe, Mn, Zn, Cu, Ni, Cr, and Co were determined by atomic absorption spectrometry in 194 plant species of 30 families and 157 soil samples. Two leaches were used for the soil – 1 M ammonium acetate (exchangeable) and 1 M HNO3 (acid soluble); a mixture of 1.5 M HNO3 and 3.7 M HCl was used for the plants. The levels of Fe, Cr and especially Ni in the soils on the ultramafic rocks exceeded those of soils on the acidic rocks. The mineral composition of plant species varies depending on the differences in chemical and mineralogical composition of the two soil-forming rock types. Taxon-specific features in the accumulation of potentially toxic elements in plants of these regions have been revealed for the first time. The data on the metal accumulation ability of plant species show that the species Thlaspi cochleariforme DC. and Alyssum obovatum (C.A. Mey) Turcz. (Brassicaceae) could be considered as Ni hyperaccumulators. These species could therefore have potential for Ni phytoextraction from contaminated soils.

Assessment of the trace element distribution in soils in the parks of the city of Zagreb (Croatia).

This paper presents the results of the preliminary testing of the selected trace elements in the soils of several parks in the city of Zagreb, Republic of Croatia. In each park, the samples were taken from several points-at various distances from the roads. The samples were taken at two different depths: 0-5 and 30-45cm. Composite samples were done for each sampling point. Microwave-assisted wet digestion of the soil samples was performed and the determination by ICP-AES technique was done. Results obtained for Al, As, Ba, Mn, Ti, V, and K are in a good agreement with the results published in the scientific literature so far. The mass fraction values of Cd, Cr, Cu, Ni, Pb, and Zn are somewhat higher than the maximum values given in the Croatian Directive on agricultural land protection against pollution. Be, Mo, Sb, Se, and Tl in the samples were present in the concentrations that are lower than their method detection limit values.

Spatial and temporal variations of trace element distribution in soils and street dust of an industrial town in NW Spain: 15 years of study

Extensive spatial and temporal surveys, over 15years, have been conducted in soil in urban parks and street dusts in one of the most polluted cities in western Europe, Avilés (NW Spain). The first survey was carried out in 1996, and since then monitoring has been undertaken every five years. Whilst the sampling site is a relatively small town, industrial activities (mainly the steel industry and Zn and Al metallurgy) and other less significant urban sources, such as traffic, strongly affect the load of heavy metals in the urban aerosol. Elemental tracers have been used to characterise the influence of these sources on the composition of soil and dust. Although PM10 has decreased over these years as a result of environmental measures undertaken in the city, some of the “industrial” elements still remain in concentrations of concern for example, up to 4.6% and 0.5% of Zn in dust and soil, respectively. Spatial trends in metals such as Zn and Cd clearly reflect sources from the processing industries. The concentrations of these elements across Europe have reduced over time, however the most recent results from Avilés revealed an upward trend in concentration for Zn, Cd, Hg and As. A risk assessment of the soil highlighted As as an element of concern since its cancer risk in adults was more than double the value above which regulatory agencies deem it to be unacceptable. If children were considered to be the receptors, then the risk nearly doubles from this element.

Trace element distribution in soils developed on gossan mine wastes and Cistus ladanifer L. tolerance and bioaccumulation

The aim of this study was to evaluate trace element distribution in soils developed on gossan mine wastes and their bioavailability for Cistus ladanifer. The ability of this shrub to accumulate these trace elements and its germination were analysed to confirm the suitability of this species for phytostabilization of mining areas in Mediterranean conditions. Plants and soils were collected in São Domingos mine and Pomarão (non-contaminated site). Concentration of As, Cu, Pb and Zn in soils (total and associated with different soil phases) and roots/leaves/seeds were analysed. Mine soils showed contamination with great total concentrations: As (2643mg/kg), Cu (226mg/kg) and Pb (7343mg/kg). Soil available fractions were small (<2.8% of total). These elements are mainly associated with residual fraction, and Fe and Mn oxides. The low As and Pb availability in São Domingos soils can be related to the presence of iron(III) lead(II) arsenates in the residual fraction. Arsenic and Zn concentrations in leaves and Cu and Zn in seeds depend on population and soil characteristics but seed viability was not different in both sites. São Domingos leaves reached toxic values for Pb due to high Pb translocation from roots to leaves (0.67–1.46), however no visible phytotoxicity signs were observed. In the São Domingos plant population, As root storage was observed. Plants from both areas were Zn-accumulators while only plants from Pomarão were Pb-accumulators. Cistus ladanifer is suitable for phytostabilization of mine soils with similar characteristics. Seed germination from São Domingos is suitable for revegetation of this mine area.

Trace element partitioning and soil particle characterisation around mining and smelting areas at Tharsis, Ríotinto and Huelva, SW Spain

Trace elements may present an environmental hazard in the vicinity of mining and smelting activities. However, the factors controlling trace element distribution in soils around ancient and modern mining and smelting areas are not always clear. Tharsis, Ríotinto and Huelva are located in the Iberian Pyrite Belt in SW Spain. Tharsis and Ríotinto mines have been exploited since 2500 B.C., with intensive smelting taking place. Huelva, established in 1970 and using the Flash Furnace Outokumpu process, is currently one of the largest smelter in the world. Pyrite and chalcopyrite ore have been intensively smelted for Cu. However, unusually for smelters and mines of a similar size, the elevated trace element concentrations in soils were found to be restricted to the immediate vicinity of the mines and smelters, being found up to a maximum of 2 km from the mines and smelters at Tharsis, Ríotinto and Huelva. Trace element partitioning (over 2/3 of trace elements found in the residual immobile fraction of soils at Tharsis) and soil particles examination by SEM-EDX showed that trace elements were not adsorbed onto soil particles, but were included within the matrix of large trace element-rich Fe silicate slag particles (i.e. 1 mm Ø at least 1 wt.% As, Cu and Zn, and 2 wt.% Pb). Slag particle large size (1 mm Ø) was found to control the geographically restricted trace element distribution in soils at Tharsis, Ríotinto and Huelva, since large heavy particles could not have been transported long distances. Distribution and partitioning indicated that impacts to the environment as a result of mining and smelting should remain minimal in the region.