JWSS - Journal of Water and Soil Science

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Soil as the third major component of our environment is exposed to different kinds of pollution. Lead has been recognized as a factor in environmental pollution. Pollution of soil and plants along the highways and roads by Pb from automobile exhaust gases has extensively been reported as the most important pollutant source in the environment. This research was carried out to determine the degree of soil pollution along the following highways: Rasht-Anzaly (Anzaly area), Kelachay-Ramsar (Ramsar area), Tehran-Karaj (Karaj area) and Isfahan-Tehran (Delijan area). In each location a transect of 100 meters long, perpendicular to the highway axis, was selected for sampling. Soil samples at different depths were taken from different distances from the highway and analysed for some physical and chemical characteristics and total Ph content by 5M HNO3 extraction.

 Results indicated that the total Pb content of soil decreased exponentially with distance from the roadside. Total Pb content of soil decreased sharply with depth in all highways except in one area indicating that Pb was retained in the surface soil and that its movement down to the deep soil was slow. Total Pb content of soils was highly and directly related to the traffic volume.

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Concentration of soluble fluoride in groundwater, soil, and some crops in Isfahan region was determined by Ion Selective Electrode (ISE) method. The mean fluoride concentration of water samples in the study area was 0.3 and 0.05 mg L^-1 in the spring and summer, respectively. These values are in an acceptable limit for irrigation, whereas for drinking water, they are in deficiency range. The average and maximum concentrations of soluble fluoride in soil samples were 1.0 and 3.2 mg kg^-1, respectively. In general, the spatial distribution of fluoride in soils showed that fluoride content around major industrial centers such as Isfahan Steel Factory, Mobarakeh Steel Co., and Isfahan oil refinery was higher than other sites. The minimum and maximum fluoride contents of crops were observed in alfalfa as 0.2 and in corn as 4.2 mg kg^-1, respectively. Tomato had the highest mean concentration of fluoride as 3.6 mg kg^-1. The fluoride concentration in plants positively correlated with the fluoride concentration in irrigation water and soil (P < 0.01) and negatively correlated with cation exchange capacity of soil (P < 0.05).

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  Phytoremediation is a new technology that employs plants to remediate contaminated soils. This method compared to those that involve the use of large scale energy consuming equipments is an inexpensive method. Phytoremediation models are useful tools to further understanding the governing processes and also to manage the contaminated soils. A thorough literature review indicates that very few models have been developed for phytoremediation due to the complexity of the phenomena. The objective of this study was to develop a simple model for phytoremediation of lead and cadmium. A new formulation of phytoremediation was established based on soil and plant responses to heavy metal pollution. A large quantity of a sandy loam soil was thoroughly mixed to ensure homogeneous different concentration levels by lead and cadmium. These contaminated soils were transferred to some plastic pots. Land Cress (Barbarea verna) and Spinach (Spinacia oleracea L.) seeds were germinated in pots containing 8 kg of contaminated soil. Plants were harvested at five time intervals. The concentrations of Pb and Cd in the plant and soil samples were digested by wet oxidation and 4 M Nitric acid digestion methods, respectively, and were determined by flame and graphite furnace atomic absorption spectrometry methods. Proposed models then were calibrated using the collected data and validated quantitatively. The results indicated that the soil adsorption isotherms followed a linear form for both Pb and Cd concentrations. The results also indicated that the phytoremediation rate of Pb by Land Cress and Spinach are first-order function of Pb concentration in soil. In contrast, a zero-order function of soil Cd contaminations was obtained. Combining these two results of soil and plant responses to Pb and Cd pollution, a simple model with reasonable performance was derived to predict the time needed for remediation of soil Pb (R² > 0.98). However, in the case of Cd, the derived models appeared to be useful to make only some overall estimations of the remediation (R²≈^�0.70).

 

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  Some industrial processes, such as plating and gold mining, utilize cyanide, which entering in their effluents. Because cyanide compounds are toxic contaminants, the waste-containing cyanide must be treated before discharge in the environment. Several methods are available for cyanide removal or detoxification. Natural degradation, alkaline chlorination, and oxidation with hydrogen peroxide are the most common methods in full-scale plants. Because of technical and economical concerns related to these methods, biological treatment processes have recently come under consideration. In phytoremediation, plants potential for pollutant removal is used. The main objective of present study is to investigate feasibility and potential of phytoremediation of cyanide-polluted soils by non-woody plants. The experiments carried out in this study were a completely random factorial design procedure, with three replications. Three non-woody plants: sorghum (as a cyanogenic cereal plant) and fescues with and free of endophyte (as grasses), were examined. Analysis of variance of the data obtained on soil cyanide reduction and cyanide accumulation in plants showed that phytoremediation is a suitable technique for low concentration of cyanide-polluted soils. Besides, it was been found that sorghum has a better soil cyanide removal efficiency than fescues, so that a significant portion of soil cyanide will accumulate in sorghum tissues.

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Phytoremediation is a new, in-situ and emerging remediation technology for contaminated soils. This technology, compared to other methods, is a sustainable, natural, relatively cheap and applicable to large scale area. Modeling phytoremediation provides quantitative insight for the governing process as well as for managers to assess the remediated sites. The objective of this study was to introduce a macroscopic phytoremediation model for Ni and Cd- polluted soils. The proposed model assumes that relative transpiration reduction function can resemble total soilNi and Cd concentrations. Combining the related functions of soil and plant responses to soil Ni and Cd concentrations, the phytoremediation rate of Ni and Cd was predicted. In order to test the proposed model, large quantities of soil were thoroughly polluted with Ni and Cd. Upland Cress (Lepidum sativum) and Ornamental Kale (Brassica olerace var. Viridis) seeds were then germinated in the contaminated soils. The experimental pots were irrigated with fresh water to reach field capacity. Upland Cress and Ornamental Kale were harvested three and four times, respectively. At each harvest, relative transpiration, Ni and Cd contents of soil samples and plants were measured. Comparison of the maximum error, root mean square error, coefficient of determination, modeling efficiency and coefficient of residual mass indicated that the non-threshold non-linear model provide high efficiency to predict relative transpiration for Upland Cress and Ornamental Kale, respectively. The results also indicated that the proposed macroscopic model can well predict the phytoemediation rate of the Ni and Cd by Upland Cress (R2>0.83) and Ni by Ornamental Kale (R2=0.78).

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Among the environmental pollutants, heavy metals according to their irresolvable and physiological effects on living organisms at low concentrations, are of special importance These elements due to low mobility are gradually accumulated in soil Being accumulated in soil, they eventually enter the food chains and threaten human health and other creatures Therefore, studying concentration distribution of heavy metals for soil pollution monitoring and maintaining environmental quality is essential In this study we investigated the effect of agricultural land use and geology on the concentration of heavy metals contamination of soil and spatial distribution map, using collected data, GIS and GeostatisticsUsing systematic stratified random sampling, 135 surface soil samples( 0-20 cm) from an area of 7262 sq km area and we measured total concentration of elements Nickel, Chromium and Cobalt and soil characteristics including pH, organic matter and texture. The mean value of elements concentrations turned out to be Cr: 88.9+22.7 Co: 17.6+3.5 Ni 63.1+17.7 mg per kg and the mean acidity is 7.8 which in the area is an indication …… property. Formetal concentrations interpolation procedures, Geostatistics was used. By the aid of spatial correlation analysis, appropriate interpolation method using functions mean absolute error and bias average error were selected. Interpolation map concentrations of heavy metals Chromium, Cobalt and Nickel with ordinary kriging method and the exponential model were developed Interpolation map analysis of heavy metals by the aid of geological and land use maps show that the distribution of the elements Chromium, Cobalt and Nickel are consistent with the geology classes However, they did not match the agriculture pattern Findings of this study in the area give us appropriate information about the concentration distribution of heavy metals Chromium, Cobalt and Nickel which can be used in monitoring and evaluation processes of heavy metals pollution in agricultural lands area. But on the other hand sampling in the areas far away from human effects, showed that the heavy metals concentration is naturally high.

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Waste tire rubbers are considered one of the environment pollutants. Increased production of these pollutants has led to more serious consideration of ways to reduce the harms caused by their accumulation in the environment. Therefore, the effects of incorporation of waste rubber crushed particles in two sizes of 1-2 and 3-5 mm and the amounts of 0, 5, 10 and 20 Mg ha-1 in a calcareous soil (0-30 cm depth) on some chemical properties of soil was investigated in Isfahan University of Technology research field (Lavark). This experiment was performed using seven treatments along with a non amended control treatment in a randomized complete block design with three replications in 1387. Eight months after incorporation, soil samples were collected for laboratory analyses. Results of ANOVA tables show that soil pH, electrical conductivity, percentage of total nitrogen and DTPA-extractable concentrations of cadmium, lead, copper and iron were not significantly affected by application of rubber particles. Incorporation of rubber particles into the soil significantly increased soil organic carbon and carbon to nitrogen. Increases in the DTPA-extractable Zn in soils treated with 10 and 20 Mg ha rubber particles in fine and coarse sizes were significant in comparison with the control soil. DTPA-extractable Zn content in the soil treated with 10 and 20 Mg ha 3-5 mm waste tire rubbers particles was about two and three times higher than that in the control treatment, respectively. The results of this study showed that in short-time, incorporation of crushed tire rubbers particles had no significant effect on most chemical properties of the soil but increased the available Zn content. In this regard, further studies to monitor the effects of adding waste rubber crushed particles on organic matter mineralization, plant toxicity and physical properties of soil in long-term are recommended.

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This research was carried out to determine spatial distribution of heavy metals concentration in soil particle size classes using Landsat ETM+ reflectance in Southern Isfahan city in the vicinity of Bama mine. To fulfill this goal, 100 compound soil surface samples were collected randomly from the area. The samples were air dried and soil particle size classes 250-500, 125-250, 75-125, 50-75 and <50 μm were determined using appropriate sieves after dispersion of the bulk samples of soil using ultrasonic apparatus. Total Zn, Pb and Cd concentrations were measured using Atomic Absorption Spectrophotometer after wet digestion of samples in acid nitric. The results indicated significant negative correlation coefficients between heavy metals concentrations of soil particle size classes and soil spectral reflectance in the visible, near infrared and panchromatic bands of Landsat ETM+ satellite. Stepwise multiple regression models were used for estimating heavy metals concentration in soil particle classes through satellite data. Furthermore, spatial distributions of heavy metals were mapped using stepwise multiple regression equations. Results also showed heavy metals concentrations in all soil particle size classes were maximum close to the mines and decreased by increasing the distance from these sources.

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Soil pollution and accumulation of heavy metals in soils and crops are the most important bioenvironmental problems that threaten the life of plants, animals and humans. This study was conducted to explore contamination of heavy metals in soils of Hamadan province. A total of 286 composite surface soil samples (0-20 cm) were collected thoroughout the province. After preparation of the samples, the total contents of Zn, Pb, Cu, and Ni in soil samples were extracted using HNO3. Total contents of heavy metals were measured by ICP. Contamination factor results showed that most samples were moderately polluted and contamination factor for lead was highly polluted. Interpolated distribution map of contamination factors (CF) and pollution load index (PLI) of the heavy metals were prepared using GIS. The overlap of CF and PLI maps with geology and land use maps indicated that the concentrations of Ni, Pb, Zn, and Cu have been controlled by natural factors such as parent material, but agricultural activities according to excessive consumption of animal manure and chemical fertilizers can increase most of these elements in soil.

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Determining the spatial distribution of different contaminants in soil is essential for the pollution assessment and risk control. Interpolation methods are widely used to estimate the concentrations of the heavy metals in the unstudied sites. In this study, the performances of interpolation methods (inverse distance weighting, local polynomials and ordinary Kriging and radial basis functions) were evaluated to estimate the topsoil contamination with copper and nickel in Golestan Province. 216 surface soil samples were collected from Golestan province, and their Cu and Ni concentrations were measured. Soil contamination was determined using different interpolation methods. Cross validation was applied to compare the methods and estimate their accuracy. The results showed that all the tested interpolation methods have an acceptable prediction accuracy of the mean content for soil heavy metals. RBF-IMQ and IDW1 methods had the lowest RMSE, whereas RBF-TPS method with the largest RMSE estimated a larger size for the polluted area. The greater the weighting power, the larger the polluted area estimated by IDW. Compared with the ‘‘sample ratio over the pollution limits” method, the polluted areas of Cu and Ni were reduced by 8.38% and 6.14%, respectively.

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Cadmium (Cd) is a metal with high toxicity and solubility in water, which is a serious environmental threat to human health. Phytoremediation is an environment-friendly method and a promising new and cost effective technology that uses plants to clean organic and inorganic contaminated media. This study was conducted to evaluate the potential of Jatropha curcas for remediation of soils contaminated with Cd. Seedlings were planted in the soil spiked with Cd in amounts of 0, 25, 50, 75, 100 and 150 mg kg^-1 (Cd₀, Cd₂₅, Cd₅₀, Cd₇₅, Cd₁₀₀ and Cd₁₅₀) for a period of five months. Biocentration factor (BCF, metal concentration ratio of plant roots to soil), translocation factor (TF, metal concentration ratio of plant shoots to soil) and removal efficiency (RE, total metal removed by plant biomass to total metal loaded in soil) were determined. Cd concentrations among plant parts were in the following trend: roots>stems>leaves. The highest total Cd concentration (up to 1100 mg kg^-1) and the highest RE were found in Cd₁₅₀ and Cd₂₅, respectively. BCF and TF of the plant were more and less than 1, respectively. Hence, although this species has a potential to be used in phytostabilization of Cd-contaminated soil, more researches in the field condition are needed.

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Pollutants are considered the disturbing factors of environment, and among them the heavy metals are more important considering their non-degradability and physiological effects on organisms in low concentrations. The goal of this research was to investigate the effect of industrial landuse on Cd and Pb concentrations in surface soils of the southwest Isfahan. According to satellite images and topographic maps (1:50000) of the study area, soil samples (depth: 0–20 cm) were collected using random sampling. A total of 38 surface soil samples were obtained from industrial areas (lowest distance = 1480 m) in the area of 73481 ha. Total concentrations of Cd and Pb in the digested solution were measured by Atomic Absorption Spectrophotometry (AAS). Using Arc GIS, the spatial distribution patterns and Cd and Pb variography of samples were analysed and finally the best models of spatial distribution of heavy metals were achieved. The primary results showed that the mean concentrations of Cd, and Pb of surface soil samples in industrial areas were 1.8 to 31.5 mg Kg^-1 higher than the world’s mean values, respectively. Although the mean concentrations of Cd and Pb were respectively 8 to 700 mg Kg^-1 lower than the standard of Iranian Department of Environment for industrial landuse.

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The aim of this work was to study distribution of some heavy metals in different soil particle-size fractions and to assess their spatial distribution. The study was carried out in Kafe Moor (Kerman, Iran) where the Gol-Gohar Iron Mine is located. One hundred twenty composite soil samples were randomly collected and transferred to the laboratory in bags. After air-drying, the samples were fractionated into six classes including 2- 0.5, 0.5-0.25, 0.25-0.125, 0.125- 0.075, 0.075-0.05 and <0.05 mm. Elemental concentrations (Fe, Mn, Cu, Zn, Pb and Ni) were determined using acid digestion method (HNO₃, 4.0 N) and an atomic absorption spectrophotometer in each class. Ordinary Kriging technique was used for predicting spatial distribution of heavy metals. The results showed that content of metals in soil increased with decreasing particle size. The results also showed that the concentration of Fe, Mn, Cu, Zn, Pb and Ni in <0.05 mm size fraction were 2.13, 1.70, 4.79,2.43, 1.42, and 3.47 times higher than in 2-0.05 mm size fraction, respectively. In addition, mapping the concentrations of heavy metals with kiriging showed that metals pollution decreased with increasing distance from mines area.
 

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