Concentrations Of Elements In Soils Research Articles

Trace Element Content in Soils with Nitrogen Fertilisation and Humic Acids Addition

Application of mineral fertilisers can entail an increase in trace element content in the soil. In consequence, their elevated uptake by plants and transfer to further trophic chain links may occur. The aim of the research reported here was to determine the usefulness of the tested organic materials, such as humic acids, for reduction of the content of trace elements in two soils fertilised with excessive doses of nitrogen fertilisers. Soil type had a considerable effect on soil trace element content. The content of most trace elements (cadmium, lead, chromium, cobalt, nickel, manganese, and iron) was higher in loamy sand than in sand. Among the tested fertilisers, a higher content of most soil trace elements was found after the application of ammonium nitrate. Urea fertilisation led to a decrease in the content of cadmium, chromium, copper, and zinc in both soils; cobalt, manganese, and nickel in sand; and an increase in concentration of cobalt and manganese in loamy sand, relative to the subjects fertilised with ammonium nitrate. Urea ammonium nitrate solution (UAN) decreased the content of chromium, cadmium, copper, nickel, and zinc in both soils; lead in the sand; and cobalt in the loamy sand, while raising the content of lead in the loamy sand, relative to the subjects fertilised with ammonium nitrate. The impact of urea and UAN on the remaining trace element content in the soils was comparable to that effected by ammonium nitrate. The effect of humic acids on trace element content in the soil tended to be beneficial, as they reduced the soil concentrations of these elements compared to the control subject (without their application). However, it should be emphasised that their effect depended on nitrogen fertiliser form and soil type. Humic acids can effectively reduce the uptake of trace elements by some plant species.

Effect of wildfire on soil element concentrations in Mediterranean Türkiye

Effect of wildfire on soil element concentrations in Mediterranean Türkiye

Are Mosses Used in Atmospheric Trace Metal Deposition Surveys Impacted by Their Substrate Soils? A National Study in Albania.

This research used moss biomonitoring to assess the atmospheric deposition of selected trace metals across the whole territory of Albania, a country of diverse lithology, and topography. Here, we assess three elements (Cr, Ni, and Co) that were identified in high concentrations compared to values reported by European moss surveys of 2010 and 2015. The possibility of element uptake by moss from substrate soils was assessed by analyzing moss and topsoil samples from the same areas. For this purpose, moss (Hypnum cupressiforme (Hedw.)) and topsoil samples were collected throughout Albania. Higher concentrations of elements in moss were found in areas of very high element content in soil characterized by no/or thin humus layer and sparse vegetation that stimulates soil dust generation. To compensate for the natural variation of the elements and to show their anthropogenic variation, geochemical normalization was conducted as the ratio of Co, Cr, and Ni concentration data to be concentration. Associations between elements in moss and soil samples, investigated by Spearman-Rho correlation analysis, indicated strong and significant correlations (r > 0.81, p = 0.000) between elements' data in moss or soil, and weak or no correlations (r < 0.4, p > 0.05) between the same data of moss and soil. Factor analysis revealed two main factors that selectively affect the elements in moss and top soil samples. Findings from this research suggested negligible interactions between moss and substrate soils, with the exception of soils with high concentrations of elements.

Mineral elements and their relation to anthocyanin content in pigmented rice plants using definitive screening design and self-organizing maps.

Mineral elements are nutrients required by an organism to perform functions necessary for survival. Stress-induced metabolism following nutritional stress has been reported to increase levels of anthocyanin. However, the role of mineral elements commonly found in soil and their contribution to the accumulation of anthocyanin content in rice plants is uncertain. Amongst the ten mineral elements investigated, the cultivation of rice plants in clean sand showed that the Mg-, Se-, and Cu-treated plants had the highest accumulated anthocyanin content in the leaves, whereas B, Cr, and Se had the greatest effect on grains. Yield component data showed major positive effects from Mg, Cr, and B. The interaction of Zn*Se and Mg*Cu positively affected the anthocyanin content in grains. The self-organizing map indicated that the total anthocyanin content was relatively proportional to the concentration of Mn, B, and Cr, but disproportional to that of Se. However, rice plants with added Fe produced the smallest amount of total anthocyanin content, less than the control, in the four stages of rice growth. The appropriate concentrations of mineral elements in soil could promote the proliferation of anthocyanin content in rice plants and grains. © 2023 Society of Chemical Industry.

Effect of microfertilizers on the content of trace elements in soil during cultivation of medicinal plants

Relevance. At present, the issues of mineral nutrition of medicinal plants with essential elements remain unstudied, and the lack of certain microelements in soils is an underestimated agroecological factor. This necessitates the study of the effect of different doses of zinc and copper fertilizers on the content of mobile forms of zinc and copper in the meadow-chernozem soil when cultivating Achillea millefolium L. and Tanacetum vulgare L. in the southern forest-steppe conditions of Western Siberia.Methods. The research objects were meadow-chernozem soil, Achillea millefolium L., Tanacetum vulgare L. The field experiment was conducted during 2012–2015 on the experimental field of the Omsk State Agrarian University. Microfertilizers in the experiments were applied once in the year of planting medicinal plants. Zinc fertilizers (CH3COOH)2Zn) were applied in doses of 20, 40, 60, 80 kg/ha, copper (CH3COOH)2Cu) in doses of 2.4, 4.9, 7.2, 9.7 kg/ha against macrofertilizer (N135P45K45). Soil samples were collected and analyzed annually in the growing phase.Results. The research revealed that zinc and copper fertilizers on optimal macroelement background at low zinc (&lt; 2,0 mg/kg) and copper content in soil (&lt; 1,5 mg/kg) provided increase of zinc and copper mobile forms content in soil by 108,3% and 54,5% (Achillea millefolium L.) and 672,7% and 61,5% (Tanacetum vulgare L.), respectively, when applied in soil in acetate form. Optimal levels of the content of mobile forms of zinc and copper in the soil were 2.5 mg/kg and 0.17 mg/kg for Achillea millefolium L. respectively, 8.5 mg/kg and 0.21 mg/kg for Tanacetum vulgare L.

Chloroform‐labile trace elements in soil via fumigation‐extraction: Steps towards the soil microbial ionome beyond C:N:P

AbstractSecondary and trace elements may be limiting soil microbial functioning, albeit microbial demand and content remain largely unknown and methods for their in situ detection are limited. Thus, the objective of the present study was to take the first step towards the method development for the assessment of the soil microbial ionome, that is, the elemental composition of soil microbial communities. Chloroform (CHCl3) fumigation extraction was used for the detection of microbial CHCl3‐labile secondary and trace element concentrations in soils. The suitability of two extractants (NH4NO3, CaCl2) for the quantification of CHCl3‐labile concentrations of phosphorus, sulphur, potassium, sodium, and magnesium, as well as selenium, iron, zinc, manganese, copper, cobalt, nickel, molybdenum, vanadium, boron, silicon, barium, arsenic, and cadmium, were tested in six agricultural soils. Additionally, three soil to extractant ratios (1:5, 1:10, and 1:20) and two extraction durations, 1 or 2 h, were tested in a subset of two soils. Out of the two extractants tested, 0.01 M CaCl2was found to be the best‐suited extractant. For CaCl2, a soil‐to‐extractant ratio of 1:20 with an extraction time of 1 h was best for the majority of elements in the two soils tested. In a limited number of agricultural soils, we were able to show that CHCl3fumigation extraction can successfully be applied to the elements phosphorus, sulphur, potassium, sodium, magnesium, zinc, manganese, copper, nickel, vanadium, boron, silicon, and barium to yield a CHCl3‐labile element fraction. Conversion values to microbial biomass, accounting for elements contained in the cell envelope components, which are mostly not extractable, and to account for adsorption to soil colloids during extraction are yet to be determined in a larger variety of soils. To overcome some of the limitations of the fumigation extraction approach for secondary and trace elements, a pre‐extraction step may provide a suitable solution.

Levels of Some Metal Contents in the Soil and Leafy Vegetables Collected From Al-Qanat Highway/ Baghdad City

The aim of the present study is to estimate the levels of some essential and non-essential metals content of soil and seven leafy vegetable species, in the field 30m away from the Al-Qanat highway in Baghdad using X-ray fluorescence analysis. The results showed that soil and leafy vegetables had higher levels of macro elements, and that Ca in rocket and purslane was the highest. The average content of trace elements in soil and leafy vegetables has been close to the minimum than the range of permissible limits recommended by WHO and FAO/WHO except Fe, Cr and Ni in soil have exceeded the concentration of the threshold limit (13728.8 mg/kg Dw for Fe, 183.361mg/kg Dw for Cr, and 124.01mg/kg Dw for Ni) value as well for leafy vegetables, the concentration of Fe (573.29 mg/kg Dw in spinach and 540.41 mg/kg Dw in rocket) and zinc (183.52 mg/kg Dw in mallow, and 181.19 mg/kg Dw in purslane) exceeded the permissible limits. The values of As, Cd, Pb and Hg concentrations in soil have been within the range of permissible limits recommended by WHO while in leafy vegetables higher levels of Pb (2.58 mg/kg Dw), and Cd (2.2 mg/kg Dw), were found in the rocket, and fenugreek, respectively. Also, higher levels of Sr were found in the rocket (592.42 mg/kg Dw) and purslane (560.34 mg/kg Dw) as well as Al in spinach (186.55 mg/kg Dw). In addition, P, K, Mg (purslane), Zn (rocket, purslane, mallow), Cd (grapevine, fenugreek), and Sr (rocket, purslane) accumulated the most with the transfer factor (TF) (&gt; 1.0), followed by Ca, Mg, Fe, Co, Cu, Se, Mn, Zn, Ni, As, Cd, Pb, Hg and Sr (0.01–1.0), while Cr, and Al had the lowest accumulation (&lt; 0.01).

Peat Decomposition and Erosion Contribute to Pond Deepening in a Temperate Salt Marsh

AbstractSalt marsh ponds expand and deepen over time, potentially reducing ecosystem carbon storage and resilience. The water filled volumes of ponds represent missing carbon due to prevented soil accumulation and removal by erosion and decomposition. Removal mechanisms have different implications as eroded carbon can be redistributed while decomposition results in loss. We constrained ponding effects on carbon dynamics in a New England marsh and determined whether expansion and deepening impact nearby soils by conducting geochemical characterizations of cores from three ponds and surrounding high marshes and models of wind‐driven erosion. Radioisotope profiles demonstrate that ponds are not depositional environments and that contemporaneous marsh accretion represents prevented accumulation accounting for 32%–42% of the missing carbon. Erosion accounted for 0%–38% and was bracketed using radioisotope inventories and wind‐driven resuspension models. Decomposition, calculated by difference, removes 22%–68%, and when normalized over pond lifespans, produces rates that agree with previous metabolism measurements. Pond surface soils contain new contributions from submerged primary producers and evidence of microbial alteration of underlying peat, as higher levels of detrital biomarkers and thermal stability indices, compared to the marsh. Below pond surface horizons, soil properties and organic matter composition were similar to the marsh, indicating that ponding effects are shallow. Soil bulk density, elemental content, and accretion rates were similar between marsh sites but different from ponds, suggesting that lateral effects are spatially confined. Consequently, ponds negatively impact ecosystem carbon storage but at current densities are not causing pervasive degradation of marshes in this system.

Choose Your Procedure Wisely: Removal of Outliers is Inappropriate for Estimating Background Concentrations of Trace Elements in Soil.

Background concentrations of trace elements in soil, i.e., the natural abundances of metals and metalloids in soil, have been the subject of much scientific discussion. This article attempts to clarify the concept, particularly from the perspective of environmental toxicology and chemistry. This article is protected by copyright. All rights reserved. Environ Toxicol Chem 2022;00:0-0. © 2022 SETAC.

Relationships between soil and badger elemental concentrations across a heterogeneously contaminated landscape

Understanding the links between environmental and wildlife elemental concentrations is key to help assess ecosystem functions and the potential effects of legacy pollutants. In this study, livers from 448 European badgers (Meles meles) collected across the English Midlands were used to investigate the relationship between elemental concentrations in topsoils and wildlife. Mean soil sample concentrations within 2 km of each badger, determined using data from the British Geological Survey's ‘Geochemical Baseline Survey of the Environment’, were compared to badger liver elemental concentrations, focusing primarily on Ag, As, Cd, Cr, Cu, K, Mn, Pb, Se, Zn. Generally, the badgers appeared to have elemental concentrations comparable with those published for other related animals, though Cu concentrations tended to be lower than expected. While there was no relationship between soil and badger liver concentrations for most biologically essential elements, biologically non-essential elements, specifically Pb, Cd, As, and Ag, were positively correlated between soil and badger livers. Lead and Cd, the elements with the strongest relationships between soils and badger livers, were primarily elevated in badgers collected in Derbyshire, a county with a millennia-long history of Pb mining and significant Pb and Cd soil pollution. Cadmium concentrations in badgers were also, on average, almost nine times higher than the local soil concentrations, likely due to Cd biomagnification in earthworms, a dietary staple of badgers. While badgers are good models for studying associations between soil and wildlife elemental concentrations, due to their diet, burrowing behaviours, and site fidelity, all flora and fauna local to human-modified environments could be exposed to and impacted by legacy pollutants.

Potential accumulation of toxic trace elements in soils during enhanced rock weathering

AbstractTerrestrial enhanced rock weathering (ERW) is a carbon dioxide removal technology that aims at accelerating one of the most powerful negative feedbacks on Earth's climate, the chemical weathering of silicates. To achieve this, ERW proposes to spread ground silicate rock on agricultural soils. According to many models, global application rates of 40 tonnes of ground basaltic rock per hectare and per year would be necessary to sequester a significant amount of CO2, representing up to 24% of the current net annual increase in atmospheric CO2. When assessing the viability of ERW as a global geo‐engineering strategy, a pivotal but overlooked question to address is whether ERW may lead to toxic trace element accumulation in soils at unauthorized and potentially harmful levels. This study evaluates the legal sustainability of ERW with regard to trace element contents in soils. We compare different trace element accumulation scenarios considering a range of rock sources, application rates and national regulatory limits. The results indicate that, at the suggested annual application rate of 40 tonnes per hectare, the first regulatory limits would be exceeded after 6 and 10 years for copper and nickel, respectively. This study argues in favour of close tailoring of ERW deployment to local conditions in order to tap into its climate mitigation potential while preserving long‐term soil uses.Highlights Terrestrial enhanced rock weathering (ERW) is a carbon sequestration technology that consists in applying rock powder to soils. This study evaluates whether rock powder application can lead to trace metals accumulation in soils beyond regulatory limits. ERW can lead to the overrun of some environmental regulatory limits within less than a decade. Specific site and rock selection will be necessary for this method to preserve long‐term soil uses.

Characteristics of B, Zn and Se in stream sediments of Tanzania and their agricultural applications: Based on 1:1000000 geochemical survey

Tanzania is located in eastern Africa with a predominantly agricultural ecomomy, the potential for developing and utilizing cultivated land are promising, but scientific guidance is required. B, Zn and Se are essential micronutrients for plants and human body with crucial biological functions, in particular, Se is significant for human health and considered as “the king of anti-cancer”. As these elements required by human or plants are mainly absorbed from soil directly or indirectly, therefore, it is important to understand the contents and distributions of them in the soil of cultivated land for guiding agricultural production. In this work, low-density geochemical survey at the scale of 1:1000000 was carried out in Tanzania, and the results show that the concentrations of B, Zn and Se in stream sediments are low and their distributions are heterogeneous. According to the distributions of geological units, the existing cultivated land resources can be divided into five regions in Tanzania. Compared with the national background values, the concentrations of B, Zn and Se are insufficient overall but enriched locally in these regions. In general, element concentrations in stream sediments and soil have a positive correlation because of their similar sources, which is essential in agriculture application. Based on the information provided by low-density geochemical data and maps, the Se-sufficient and Se-rich regions were delineated in Tanzania, where can be used to develop Se-rich industries. Finally, this paper believes that geochemical survey is a powerful tool for cultivated land evaluation, agriculture management and land development.©2023 China Geology Editorial Office.

Plant nutrient contents and spatial distribution patterns of toxic element concentrations in mine site soils

Open-pit coal mining causes land and soil degradation and negatively affects soil properties. It is of great importance to determine variabilities in soil properties of the abandoned area after the mine is closed and to bring it back to nature by implementing appropriate rehabilitation programs. The aim of this study was to evaluate plant nutrient availability and toxic element pollution in an abandoned coal mine site. The results indicated that the amounts of plant-available P and K are quite low (<90 kg P2O5 ha-1) and low to moderate (<170 kg K2O ha-1), respectively. The concentrations of plant available Fe (>4.5 mg kg-1) and Cu (>0.2 mg kg-1) are too high in the whole study site. Soils in the study area generally have low organic matter content with ranging from 0.42% to 3.67%. Toxic element concentrations, especially Ni (>75 mg kg-1) and Cr (>100 mg kg-1), are extremely above the optimum levels, posing a great risk in the open-pit area (abandoned), the dump sites and the coal storage area.

Measurement of Concentration of Some Heavy Elements in Soil and Some Vegetable Areas of the Capital Baghdad

In this research, we collected 10 samples, 2 soil and 8 vegetables cultivated in orchard area allowing district agricultural land in Al-Khatib at a few distances from Kadhimiya district, and adjacent to the area Al-Huria samples are congested as in table 2 after the chemical digestion of the seamount by using the atomic absorption technique, we found the following results: The highest value of Cadmium in A5 sample was 0.0436 ppm and 0.026933 ppm, the highest value of Lead in the sample A1 (soil of Kadhimiya) was 0.07345 ppm average and the highest value of Brass in A2 was 1.1176 ppm and 0.1762 ppm. The highest value of Cadmium in B4 (Rashad) was 0.0514 ppm and 0.04303 ppm, and the highest value of Lead in B5 (Kirath) was 0.365 ppm and on average 0.2293 ppm, the value of Copper in B4 (Rashad) was 1.1491 ppm and 0.20185 ppm in seriously. The limits are permitted within the WHO (World Health Organization), and therefore, there is no contamination of these items in these regions A and B (allows bastinade Kadhimiya, Khatib) respectively.

Effects of anthropogenic and natural environmental factors on the spatial distribution of trace elements in agricultural soils

The concentrations of trace elements in agricultural soils directly affect the ecological security and quality of agricultural products. A comprehensive study aimed at quantitatively analyze the effects of anthropogenic and natural environmental factors on the spatial distribution of heavy metals (HMs) and selenium (Se) in agricultural soils in a typical grain producing area of China. Factors considered in this study were parent rock, soil physicochemical properties, topography, precipitation, mine activity, and vegetation. Results showed that the median values of Zn, Cd, Cr, and Cu of 111 topsoil samples exceeded the background values of Guangxi province but were lower than the relevant national soil quality standards, and 85% of soil samples were classified as having rich Se levels (0.40 −3.0 mg kg−1). The potential ecological risk index of soil heavy metals as a whole was low, with Cd in 9% of the samples posing moderate ecological risk. The concentrations of heavy metals and Se were relatively high in soils from shale rock. Soil properties, mainly Fe2O3 and Mn played a dominant role on soil HMs and Se concentrations. Based on GeoDetector, we found that the interaction effects of two factors on the spatial differentiation of soil HMs and Se were greater than their sum effect. Among the factors, Mn enhanced the explanatory power of the model the most when interacting with other factors for soil Zn; the greatest interactive effect was between distance from mining area and Mn for Cd (q = 0.70); Fe2O3 significantly promoted the spatial differentiation of soil Cr, Cu and Se when interacting with other factors (q > 0.50). These findings contribute to a better understanding of the factors that drive the distribution of HMs and Se in agricultural soils.

Soil Contamination and Risk Assessments on Selected Dumpsites within the Basement Complex and Sedimentary Formations of Ogun State, South-western Nigeria

The concentrations of inorganic elements in soils of Saje, Ita-Oshin, Premier, and Oke-Diya dumpsites were determined using an X-Ray Fluorescence spectrometer to assess the soil quality through chronological changes with depths. A soil core sampler collects 56 samples at 20, 40, 60, and 80 cm depths. Saje showed high mean concentrations of Ca, K, Fe, Rb, and Ti at all depths, while Oke-Diya revealed high mean concentrations of Ca, K, Fe, Rb, Ti, Mn, Zn, V, Cr, and Ni at all depths. These concentrations were in a closed range suggesting a build-up of elements in the soil profiles. Oke-Diya had the highest pollution index, followed by Saje, and the contaminations were from anthropogenic and geologic sources. The mean concentrations of Fe, Zn, Ni, Mn, Ti, K, and Ca were high at all depths in Ita-Oshin, and in Premier, the mean concentrations of K and Fe were high at all depths. Premier had the lowest pollution index. Ita-Oshin and Premier enrichment factors showed geologic sources. Saje and Oke-Diya revealed unacceptable non-carcinogenic risks for adults and children, and Ita-Oshin and Premier recorded acceptable limits. Saje and Oke-Diya samples had high carcinogenic risks for adults due to Cr, Pb, and As. Elements Cr and As in Ita-Oshin, and Pb in Premier evinced unacceptable carcinogenic risks for adults. Saje, Oke-Diya, and Premier indicated unacceptable carcinogenic risks for children due to Cr. The study showed toxins build-up in the soil system, and the study areas are not suitable for growing crops and sinking water wells for agricultural and domestic uses.

Factors conditioning the content of chemical elements in soil and mosses in Armenia

In this research, chemical element contents were determined using the Epithermal neutron activation analysis (Cr, V, Ti, Sr, Rb, As, Zn, Co, Fe, Mn and Ba) and atomic-absorption spectrometry (Cu and Pb) for mosses and X-ray fluorescence spectroscopy (Cr, V, Ti, Sr, Rb, As, Zn, Cu, Co, Fe, Mn, Pb, and Ba) for soil samples. The research team combined compositional data analysis and geospatial mapping to reveal key factors conditioning moss and soil chemical composition. The results showed that significant correlation was detected between Cr, Sr, Rb, As, and Pb for Syntrichia ruralis moss and soil contents suggesting their origin stemming from soil resuspension. Meanwhile, in the case of pleurocarpus (Homalothecium philippeanum) moss species, the mechanisms conditioning the transfer of elements to mosses from dead or living plant materials were found to be responsible for mosses Zn, Sr, Mn, Rb, As, Ba, Cu contents. Both media were identified to display multivariate outliers in the same sampling sites which were characterized by the presence of natural mineralization and mining and smelting activities. The compositional PCA and k-means clustering show that the soil element content groupings are in line with the geological base, whereas in the case of mosses, the rural and urban gradient plays a pivotal role in the spatial separation of the identified clusters. In addition, moss samples included in a cluster representing the urban areas of the country have included typical anthropogenic elements (Pb, Cu, Zn etc.) confirming the applicability of the studied mosses in pollution source identification.

Mycorrhizal fungi improve growth of Juniperus communis but only at sufficiently high soil element concentrations

High nitrogen (N) deposition rates can cause soil eutrophication and acidification causing harmful effects to many plant species. One species that seems to be affected is Juniperus communis, populations of which are declining in Western Europe, due to a lack of regeneration. This is primarily caused by limited seedling recruitment and low viable seed production; factors that have both been attributed to increased levels of N deposition. J. communis sapling performance could be dependant on mycorrhizal fungi (MF) in their roots, but how – and under what conditions – MF contribute to the performance of J. communis has not been studied before. Here we experimentally tested the effect of MF on J. communis cuttings along an acidity gradient in situ. To manipulate the interaction with MF, we used ingrowth cores, effectively allowing for root-MF interactions or strongly reducing these. After six months we measured growth and needle nutrient concentrations of cuttings with a normal or reduced mycelial network. MF had a positive effect on absolute growth of our cuttings. However, this effect was weakened as soil Mg2+, Ca2+ and Na+ concentrations declined. Soil pH itself was not directly associated with the effect of MF on J. communis. MF also decreased needle phosphorous concentrations, most likely because the increased plant growth by MF diluted its concentration in the plants. We conclude that MF stimulate the performance of J. communis, but that leaching of cations, accelerated by N deposition, negatively affects their mutualism and thereby the performance of J. communis saplings. This highlights the potential positive role of MF in effective conservation and restoration efforts of J. communis habitats in Western Europe and the importance of prioritising the reduction of ongoing eutrophication and acidification.

Concentration, sources, potential ecological and human health risks assessment of trace elements in roadside soil in Hamedan metropolitan, west of Iran

ABSTRACT The road shipping has become one of the major metal contamination sources that could impact on roadside soils. Therefore, this study was conducted to determination, possible source identification and potential ecological and human health risks assessment of trace elements (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) in roadside surface soil samples in Hamedan, west of Iran in 2018. In so doing, a total of 63 roadside soil specimens from three main highways, including Goltapeh (G), Razan (R), and Kermanshah (K), were collected. Then, the contents of elements in roadside soils were determined using ICP-OES. Based on the results obtained, the highways with heavy traffic have the highest accumulation of all the metals, suggesting the effect of traffic density on metals concentrations. Computed values of pollution indices with mean of 0.970 for I-geo and 2.16 for PI pointed out that the soils collected from R and K roads primarily contaminated by Zn. The results of potential ecological risk assessment (RI) indicated that the surface soNo potential conflict of interest was reported by the author(s).ils at all the sites with RI < 150 have low ecological risk. Also, based on the results of human health risk assessment there was no substantial non-carcinogenic risk found to both children and adults through exposure to studied metals in roadside soil. The carcinogenic risk of Cr for both target populations was at the tolerable or acceptable level, while the other metals have no considerable carcinogenic risk. Hazard quotient (HQ) values demonstrated that ingestion was the main path of road soil metal exposure to man beings. Multivariate statistical analyses represented that Mn in the roadside soils derived from both soil minerals erosion and exhaust sources. Other metals also derived from non-exhaust sources (e.g. wear and tear of brakes, tires, engines, and lubricating oil). Our findings could be provided a theoretic basis and data support for pollution monitoring and control, soil remediation treatment and the implementation of public prevention in roadside areas of Hamedan.

Nutrition cycles in sessile oak (Quercus petraea Liebl.), Norway spruce (Picea abies L.Karst) and European beech (Fagus sylvatica L.) stands from Central Romania

In Romania, the sessile oak is the widest spread species of all native oak species, forming a lower story of vegetation. The European beech and Norway spruce cover 50% of the Romanian forest area. The purpose of this study was to analyze the variability of the leaf nutrients, as well as of the soil nutrients, for sessile oak, Norway spruce and European beech stands situated under different site conditions. The studied sites are located in the southern part of the Carpathian Mountains at altitudes varying from 600 m to 1300 m. Leaves samples were collected from twenty sessile oak trees, in three moments during the growing season. The same eight elements in total form were determined for soil and leave too: N, P, K, Ca, Mg, Fe, Cu and Zn. Leaves samples for beech and spruce were collected in the II Level Intensive Monitoring Grid of the ICP Forests Programme. The paper focuses on the seasonal concentration variation of eight macro elements in leaves and the correlations between the concentration of the macro elements in soil and litter. In addition, the study highlighted the degree of influence exerted by some soil properties on the foliar concentration of nutrients (through multiple regressions). The obtained results show different mobility of the elements and a greater variability was noticed in the case of certain elements. The same three soil properties were noticed to influence the foliar nitrogen concentration.