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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In recent decades, the use of nitrogen fertilizers has increased irrespective of their effects on soil properties, agricultural products and, particularly, on environmental pollution. Nitrate easily leaches from soils into groundwater. The objective of this study was to determine temporal and spatial nitrate concentrations in groundwater in agricultural, industrial and urban regions in some parts of Isfahan Province. Water samples were collected monthly from 75 agricultural, industrial, and urban wells of Isfahan, Najaf-abad, Shahreza, Natanz and Kashan during January-May 2001. The results indicated that NO₃-N concentrations in most of the regions studied were higher than the standard level (10 mg/l) and nitrate pollution must be reckoned among the most serious problems of sustainable agriculture and exploitation of groundwater resources. Average NO₃-N concentration in different wells ranged from 1.03 to 50.78 mg/l (4.64 to 228.5 mg/l as nitrate). The average NO₃-N concentration in groundwater of Najaf-abad, Shahreza, Isfahan and Natanz-Kashan was 17.56, 14.6, 16.04, and 8.24 mg/l and 95.5, 100, 84 and 33.3 % of total wells in these regions had nitrate concentrations above the standard level, respectively. Maximum NO₃-N concentration was detected in the agricultural region south of Najaf-abad (64.6 mg/l). Nitrate pollution in most of the sampling areas was mainly linked to agricultural activities. The average NO₃-N concentration in groundwater of all agricultural, industrial, and urban regions, except for urban regions of Natanz and Kashan, were above the standard level. Generally, nitrate concentration level in groundwater increased with time and was maximum in March and April.

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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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Tracer experiments are very important in the studies related to aquifer contamination for determination of dispersion coefficient. In this study, the effect of sampling method on the dispersion coefficients of two simulated sandy aquifers was examined. The physical model was made from Plexiglas material with inner length, width and height of 72, 10 and 120 cm, respectively. A solution containing 9 g/l sodium chloride (Ec = 14 ds/m) was used as the non - reactive (conservative) contaminant. Homogeneous sands with coarse and medium particle sizes were used as media for the simulated aquifers. The experiments were carried out in the aquifers with various thicknesses from 20 to 100 cm with 10 cm thickness increment. Point and mixed samples were taken through all experiments. The results of the study showed that (1) for both simulated aquifers, the dispersion coefficient values obtained by point sampling method were close to the values obtained by other researchers from laboratory experiments (2) In all the experiments, the dispersion coefficient values obtained by mixed sampling method were higher than those obtained by the point sampling method (3) with increasing the aquifer thickness, the dispersion coefficient values obtained from the mixed samples varied but did not have a uniform trend which could be due to the unavoidable experimental errors and (4) there was no difference between the breakthrough and pore volume curves of various aquifer thicknesses obtained from point and mixed samples. Overall, based on the results obtained from this research, in studies related to aquifer contamination, it is recommended to take point samples instead of mixed samples to obtain more precise results.

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Environment pollution is an important problem in the world. In agriculture irrigation, drainage and fertilization activities cause water resource and environmental pollution by effecting on solute, nutrient and sediment transport. Combined methods of water and nutrient management could consider in pollution transport controlling that reducing runoff and deep percolation, providing opportunity for solute infiltration, reducing sediment transport even economic and easy usage. In this research, affect of two different management in irrigation (cutback and continues) and fertilization (solid and fertigation) on nutrient loss was evaluated. Comparing nitrate, phosphor and potassium loss in different management explicate cutback flow with no uniform solid distribution of fertilizer is more useful to prevent nutrient loss. Because of similar results, increasing in fertilizer distribution in furrow length and easy usage between nitrate losses in six managements, show cutback flow with three proceeding solid, fertigation and fertigation (with 1/4, 1/2 and 1/4 ratio) fertilization was recommended replacement of cutback flow with three proceeding solid fertilization.

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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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  In this study, chemical quality of Zayandehrud river between Zayandehrud Regulating Dam and Nekouabad Diversion Dam, three discharging drains and one Fehlman well were measured using HPLC with determine the pollution concentration of diazinon insecticide from July 2006 to March 2007. Also, Zayandehrud’s assimilative capacity was determined. The results showed that river water and drains were not polluted to diazinon. Physical, chemical and biological factors effective in the diazinon detection were assessed. Diazinon was detected in the groundwater sample in October with concentration of 32.1 ng/L. This level was lower than the maximum permissible level for drinking water. Also, the NO^-₃ concentration in this month was 24 mg/L that is 2.4 times the standard level (10 mg/L). Due to the increased discharge of different wastewaters to Zayandehrud, its assimilative capacity decreased from upstream to downstream. So, prevention of use of pesticides and pre-treatment of wastewaters that are discharged to this river need more attention.

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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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Silver toxicity and its fate in the environment are currently being debated and are important as challenging research topics. Even though there are several studies on its total content in soils, fractionation of Ag especially in calcareous soils has not been investigated. Therefore, to provide fundamental information on the chemical behavior of Ag in calcareous and noncalcareous soils, we studied 8-step chemical fractions of Ag (i.e., EXCH, CARB, Me-Org, re-MeOx, H2O2-Org, am-MeOx, cr-FeOx, and RES) after 30 and 60 days of incubation in soils amended with Ag (0 and 15 mg kg-1), sewage sludge (0 and 20 t ha-1) and EDTA (0 and 0.5%). Experimental results showed that redistribution of Ag in spiked noncalcareous soils was EXCH (34%), H2O2-Org (33%) and RES (17%). In calcareous soils, after 30 days, EXCH- and RES-Ag increased but at the end of 60 days H2O2-Org-Ag increased. Based on our data, we could conclude that addition of Ag results in an increase of Ag mobility in soils but incubation and sewage sludge may have adverse effect on its mobility. In contrast to noncalcareous soil, EDTA in calcareous soil resulted in higher Ag mobility. This may have environmental implications in Ag polluted calcareous soils.

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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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Copper is considered as one of the most important nutrient elements for plants. If its contents are concentrated higher than the standard value it can be considered as a pollutant element. The content of absorbable copper in the area around Sarcheshmeh copper mine can be significantly high. In this study, samples of soil were collected in summer through a particular sampling method with chimneys of Sarcheshmeh plant as the center of sampling area within a radius of 6km, in three different directions (Rafsanjan, Sarcheshmeh City and Sarcheshmeh mine) and. The total concentration of absorbable copper and some chemical properties of soil (i.e. pH and EC) were measured for 122 surface samples (depth of 0 to 35 cm). There was a significant negative regression between pH and total absorbable copper content, and a significant negative regression was observed between EC and total absorbable copper content. The best fitted model was spherical model, and Ordinary Kriging was applied to map the absorbable copper content. Results showed that most concentration of copper occurred in the Rafsanjan direction. Also, regarding wind orientation which blows towards Rafsanjan, the chimneys probably have a significant effect on increasing copper content in Rafsanjan moreover, the copper content is substantially higher around chimneys than other areas. Also, transition of copper elements from chimneys by wind can be significant up to 4 km from Sarcheshmeh plant.

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Atmospheric dust is an important source of heavy metals, particularly in urban environments. Heavy metals can easily attach to dust particles and be distributed in large areas. The objective of this study was to evaluate the status of major heavy metals in the atmospheric dust of Isfahan and adjacent cities. A total of 144 dust samples were taken during a period from August to December 2010 from Isfahan, Khomeynishahr, Falavarjan, Mobarake and Zarinshahr cities. Dust samples were extracted with HNO3 65% and the total concentration of metals including Pb, Zn, Cd, Cu, Ni, Co, Cr and Mn in the samples was measured by an atomic absorption spectrometer. The mean concentration of these metals was 223.5, 470.3, 3.5, 71.0, 82.0, 26.5, 24.4 and 426.3 mg kg-1, respectively. Results indicated that heavy metals concentration in any area was different depending on the source of pollution and it was much higher than the mean concentration of the corresponding heavy metal in soils. Besides, the highest deposition rate of all the heavy metals in this study was found in November-December period. This could be attributed to an increase in the use of heating systems and also to a temperature inversion event prevailed in the area. Atmospheric deposition seems to be an important pathway of heavy metals addition to soils. For example, it is responsible for 35-91% and 12-47% of Pb and Cd entering the soil in the area, respectively.

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In recent years, due to the increased population, urbanization and changes in human consumption patterns, urban, industrial and agricultural soils have been exposed to various pollutants such as heavy metals. The objective of this research was to identify hotspots of Pb by using global and local Moran Indices in urban and suburban soils of Kashafrood catchment. A total of 261 surface soil samples (0-15 cm deep) were taken using irregular girding network method and their total Pb concentrations were measured. The positive Moran index at confidence level of more than 99 percent showed the spatial clusters between observations. On the basis of local Moran index results, 15 samples were introduced as hotspots (high-high value) located southeast of Mashhad plain. Exclusion of extreme values resulted in the addition of high-high cluster (hotspots) leading to the extension of these areas to the West of the Mashhad city. These areas are introduced as hotspots due to the urban land use, the direction of prevailing wind, and the area being close to Mashhad airport.

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Nowadays, due to the effective role of nitrogen fertilizer in growth, yield and crop quality, farmers apply large amount of chemical fertilizers. High application of nitrogen fertilizers has caused soil and water pollution and environmental dangers, higher nitrate accumulation in plant, and different disease risks in human and livestock. In order to investigate the effects of nitrogen and cycocel application effects on soil nitrate pollution and agronomic traits of rice, an experiment was arranged in split plot based on a completely randomized block design with three replicates at Sari region (north of Iran) in 2010. The main factor was nitrogen in four levels and cycocel was considered as a sub factor in three levels. Results showed that maximum and minimum plant height and fourth internodes bending moment were obtained in 0 and 150 kg N ha-1, respectively. Higher filled spikelet percentage per panicle, grain yield and harvest index were obtained in 100 kg N ha-1 application. Application of N up to 150 kg N ha-1 increased soil nitrate by 44.7 percent. As cycocel application decreased, the plant height and panicle length were reduced, but tiller number per plant, filled spikelet percentage per panicle, and grain yield were increased.

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One of the major problems associated with petroleum-contaminated soils is water repellency, especially in arid regions of the world. Hence, a variety of methods such as clay addition has been proposed to improve the hydrophobicity of soils. This research was conducted to evaluate the influence of zeolite application on water repellency of an oil-contaminated soil from Khuzestan Province under various treatments including initial soil moisture content (0, 10, 20, and 30 weight %), the amount of applied zeolite (2, 4 and 8 weight %), size (25-53 and <2 μm), and exchangeable cation (Sodium and Calcium). The hydrophobicity of soil sample was determined using Water Drop Penetration Time (WDPT) method. The results showed that by increasing the amount of applied mineral WDPT decreased, where the application of 2 percent of zeolite led to the reduction of WDPT by about 27 percent less than the control. The results also indicated that soils treated with sodium-saturated zeolite had less WDPT than the calcium-treated samples, where the average of WDPT in sodium and calcium treatments decreased by 23% and 5% compared with the control, respectively. The initial moisture content of 30 percent showed the best performance with the decreasing WDPT of about 67 percent. Furthermore, the effect of mineral particle sizes showed a meaningless reduction in WDPT.

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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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The present study was conducted to increase phytoextraction efficiency of Festuca ovina L. in lead contaminated soil in the EDTA-assisted (0, 1.5, 3, 1.5+1.5, 3+3, 6 mmol kg&minus;1), assess the best time of plant harvesting to increase Pb uptake and method of EDTA application to reduce Pb leaching risk. The results revealed that the greatest Pb uptake was observed in 3EDTA treatment. Therefore, 3mmolkg-1 was used in the second step for assessing harvest time for 15, 30 and 45 days. Results showed that the concentration of Pb in plant tissues was increased with the passage of time and the best harvest time to achieve maximum removal of Pb was 60 days of the first harvest. In the third step to reduce leaching of Pb-chelate, 3mmolkg-1 EDTA in five ways of single, double, triple, quadruplet, quintuplet were added to the soil. The results indicated that under quintuplet application, Pb content reached its minimum concentration in the soil and in the plant organs, the Pb concentration was maximum and metal concentration in the plant organs did not vary significantly when triple, quadruplet and quintuplet dosages were added (p<5%). Overall, optimum phytoextraction of F. ovina L. and Pb leaching reduction were achieved when 3mmol kg&minus;1 EDTA was added in quintuplet dosage and the plant was harvested at the end of growth stage.