L. Qasemi far; A. Golchin; F. Rakhsh
Abstract
Introduction: The accumulation of heavy metals in water, sediments, and soils has led to serious environmental problems. In recent years, several processes have been developed with the aim of reducing or recovering heavy metals from contaminated environments. Physical and chemical approaches are capable ...
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Introduction: The accumulation of heavy metals in water, sediments, and soils has led to serious environmental problems. In recent years, several processes have been developed with the aim of reducing or recovering heavy metals from contaminated environments. Physical and chemical approaches are capable of removing a broad spectrum of contaminants, but the main disadvantages of these methods lie in the increased energy consumption and the need for additional chemicals. In recent years, the processes such as bioleaching, biosorption, bioremediation, phytoremediation, and bio precipitation are all based on the use of microorganisms that have the ability to solubilize, adsorb, or precipitate heavy metals. Therefore, it is necessary to find some solutions to reduce the negative effects of heavy metals in soil. Materials and Methods: A factorial experiment was conducted in the greenhouse of the Faculty of Agriculture, the University of Zanjan, using a completely randomized design with three replications. In this experiment, the effects of different levels of soil cadmium (0, 5, 10, 25, and 50 mg/Kg) and soil inoculation (without inoculation and inoculation with Glomus mosseae, Glomus intraradices, Glomus mosseae + Rhizobium trifolii, Glomus intraradices + Rhizobium trifolii bacterium, Rhizobium trifolii, Glomus mosseae + Glomus intraradices and Glomus mosseae + Glomus intraradices + Rhizobium trifolii) on growth of berseem clover were assessed. Results and Discussion: The results of this study showed that the soil cadmium levels has a significant effect (p < 0.05 and p < 0.01) on fresh weights of aerial parts and roots, height, number of the plant in the pot, Fe, Zn and Cd concentrations in aerial parts and roots of berseem clover. The fresh weights of aerial parts and roots, height, number of the plant in the pot, Fe and Zn concentrations in aerial parts and roots of berseem clover decreased as the levels of soil cadmium increased. The lowest concentrations of iron and zinc were measured in treatment with 100 mg Cd/Kg. Also, Cd concentration in aerial parts and roots increased as the level of soil cadmium increased. The results of this experiment showed that soil inoculation with mycorrhizal fungi and Rihzobium trifolii had a significant effect (p < 0.05 and p < 0.01) on fresh weights of aerial parts and roots, height, number of plant per pot, Fe, Zn and Cd concentrations in aerial parts and roots of berseem clover. The inoculation of soil with mycorrhizal fungi and Rhizobium trifolii increased the fresh weights of aerial parts and roots, height and No. of plant per pot. The highest fresh weights of aerial parts and roots of berseem clover, height, and number of plant per pot were obtained in treatments co-inoculated with Glomus mosseae and Rhizobium trifolii. The highest and lowest concentrations of iron and zinc in aerial parts and roots of berseem clover were measured, respectively, for the treatment co-inoculated by Glomus mosseae and Rhizobium trifolii and control treatment (without inoculation). However, the opposite trends were found in Cd concentrations in the plant. The highest and lowest Cd concentrations in aerial parts and roots were measured in control treatment (without inoculation) and treatment co-inoculated by Glomus mosseae and Rhizobium trifolii (MT), respectively. Conclusion: Bioremediation and phytoremediation are considered as two very safe and necessary technologies which naturally occur in the soil by microbes and plants and pose no hazard to the environment and the people life. The procedure of bioremediation and phytoremediation can be simply carried out on site without initiating a major disruption of normal actions and threating the human life and the environment during transportation. Bioremediation and phytoremediation are used less than other technologies for cleaning-up the wastes and contaminated soils. Microorganisms and plants possess inherent biological mechanisms that enable them to survive under heavy metal stress and remove the metals from the environment. These microbes use various processes such as precipitation, biosorption, enzymatic transformation of metals, complexation and phytoremediation techniques of which phytoextraction and phytostabilization have been very effective. However, environmental conditions need to be adequate for effective bioremediation. The use of hyperaccumulator plants to remediate contaminated sites depends on the quantity of metal at that site and the type of soil. The results of this experiment showed that the Rhizobium trifolii and Glomus mosseae could be used to reduce the soil cadmium contamination. Also, the berseem clover is a hyperaccumulator plant for phytoremediation of cadmium in soils. According to the results of this study, co-inoculation of mycorrhizal fungus Glomus mosseae and Rhizobium trifolii can be recommended to improve the yield and uptake of micronutrients such as iron and zinc in cadmium contaminated soils.
S. Salavati-Nik; S. Saadat; M. Alameh
Abstract
Introduction: Sheshtamad area is located in the western part of Khorasan Razavi province and includes Sheshtamad city and its surrounding villages. A variety of sedimentary and igneous rock units, mainly belonging to the Cretaceous or younger age, are found in the area. A series of orogenic movements, ...
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Introduction: Sheshtamad area is located in the western part of Khorasan Razavi province and includes Sheshtamad city and its surrounding villages. A variety of sedimentary and igneous rock units, mainly belonging to the Cretaceous or younger age, are found in the area. A series of orogenic movements, lithofacies changes and magmatic activities led to the distribution of heavy elements that can cause environmental problems in the area. This study aimed to assess the heavy metal contamination of the soil in the extent of the study area. It has been attempted to investigate the origin of pollution and its impact on the environment using geochemical data.
Materials and Methods: In this study distribution and possibility of contamination from arsenic (As), lead (Pb), zinc (Zn), copper (Cu), chromium (Cr), nickel (Ni), cobalt (Co), antimony (Sb), strontium (Sr) and vanadium (V) were investigated. These variables were determined using chemical analysis of the sediments. For this purpose, network sampling was carried out at 1.5×1.5 km and 3 to 4 samples were taken from each cell. Throughout the study area (geological sheet of 1:100,000 Sheshtamad), 1248 samples of sediments were collected by Jiangxi Company and analyzed by ICP-MS method. The analysis results were summarized in ArcGIS software and elemental concentration zoning was performed by Kriging and Inverse Distance Weighting methods. Some indices have been proposed to evaluate heavy metal contamination in sediments and soils. In order to determine soil contamination with heavy metals, some parameters such as Contamination Factor and Pollution Index were calculated. Multivariate statistical analyses such as correlation analysis have been applied to identify the geochemical behaviors of different geochemical groups.
Results and Discussion: Surface distribution of As with values above 270 mg kg-1 was observed in the drainages of the southern part of the study area. Sr and Sb were measured with values above 2900 mg kg-1 in the drainages from south to eastern part, and above 4 mg kg-1 in south and central drainages, respectively. Surface dispersion of Zn above 210 mg kg-1 was present in the drainages from central, south, southwest and northwestern parts of the region. Cu and Pb were measured with values greater than 240 mg kg-1 in North and Northwestern parts, and greater than 110 mg kg-1 in East, Central and southwest, respectively. Surface distribution of Co element with values above 58 mg kg-1 from drainages in central, north and southwest and V with values higher than 85 mg kg-1 in central and southwest part were also observed. Finally, distribution of Cr element with values above 7400 mg kg-1 in east central and southwestern part and Ni with values higher than 890 mg kg-1 in center and north section were found.
Pb had significant contamination only in a small area of the central part. Cu also showed little pollution only in a small area of the center of the region on the fringes of mining activities. According to the Pollution Index, As had a high pollution in the south and west parts. The central and southwestern parts of the study area show moderate Cr pollution, based on the Contamination Factor. Based on the correlation matrix used to determine the relationship of heavy elements with each other, some elements have a positive correlation with each other, which may indicate their common origin. For example, Co had a positive correlation with Ni and Cr indicating a common origin associated with the distribution of mafic rock units in the region. Pb and Zn have a positive correlation with each other as well as with Co and V, whereas the absence or negative correlation of As with these elements indicates a separate source for this element compared to Pb, Zn, V and Co. The presence of Cu element, despite its limited correlation with zinc, appears to be independent and likely to be more closely related to mineralization processes and mining activities in the region. Sr was negatively or very weakly correlated with most elements. It is chemically similar to calcium and can be present in carbonate sediments with gypsum in addition to substituting for plagioclases. The results of correlation coefficients with elemental zoning maps, geological maps and results of pollution coefficients showed very good agreement. The results of this study indicated that heavy metal contamination in the region was mainly due to the geological characteristics of this area. In other words, that was mainly “lithogenic”.
Conclusion: The results showed that Cr in the central and southwestern parts of the region had moderate contamination and it should be considered by experts and residents of the area to prevent Cr entering the biological cycle of the region in the future. It is one of the most toxic heavy metals and contaminated areas should receive proper attention. Studies were also indicated the presence of As in the stream sediments, especially in the southern parts of the region, and it is necessary to measure the permeability of this element into groundwater and surface waters in addition to the soil. V, Sb, Zn and Co had no significant contamination and specific environmental problems at current concentrations, is unlikely. Anthropogenic contamination, except from limited mining activities, did not play a significant role in the contamination of this region.
N. Tabarteh Farahani; A.HA.H. Baghaie
Abstract
Introduction: Lead (Pb) is of great concern in environment because of its toxicity to animals and humans. Lead is a cumulative toxin and known carcinogen. Although, plants do not require Pb for growth, the bioaccumulation index of Pb in plants exceeds that of most other trace elements. It is therefore ...
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Introduction: Lead (Pb) is of great concern in environment because of its toxicity to animals and humans. Lead is a cumulative toxin and known carcinogen. Although, plants do not require Pb for growth, the bioaccumulation index of Pb in plants exceeds that of most other trace elements. It is therefore important to control Pb concentration in plants, especially in the edible parts of crops to ensure food safety. There are many factors that control Pb accumulation and availability to plants in agricultural soils such as Pb source, Pb loading rate, soil pH, soil cation change capacity (CEC), chloride concentration in soil solution and soil organic matter content. These are important factors that should be considered for evaluating Pb phyto-availability. In addition, element interactions can also affect the elements uptake. Thus, this study was performed to investigate the effect of converter sludge-enriched cow manure on the changes in corn Pb uptake in a Pb-polluted soil under greenhouse condition.
Materials and Methods: This pot experiment was conducted under greenhouse condition around the city of Arak, using a Fine loamy, mixed and thermic, Typic Haplargids soil. A factorial experiment with a randomized complete block design with 24 treatments in three replications was carried out. The treatments consisted of applying enriched cow manure (0, 15 and 30 t ha-1) with 0% and 5% pure Fe from converter. To investigate the effect of converter sludge-enriched cow manure on the changes in corn Pb uptake, a non-saline soil with low carbon percentage was selected. The soil was polluted with Pb from Pb(NO3)2 source at the concentrations of 0, 200, 300 and 400 mg Pb kg-1 soil and incubated for one month. Cow manure was produced in a local farm and aged for two years before the experiment. The cow manure was enriched with converter sludge and incubated for three months in room temperature. Then, the enriched cow manure was added to the Pb polluted soil and corn (Zea mays L. single grass 704) seeds were sown. After 60 days from the experiment, soil physio-chemical properties and soil and plant Pb concentration were measured.
Results and Discussion: The greatest and least DTPA-extractable-Pb were determined in the polluted soil (400 mg Pb) without applying cow manure and the polluted soil (200 mg Pb) treated with 30 t ha-1 enriched cow manure, respectively. The DTPA-extractable-Pb in uncontaminated soils was not detectable by atomic absorption spectroscopy (AAS). Increasing the amount of cow manure caused a significant reduction in DTPA-extractable-Pb as applying 15 and 30 t ha-1 cow manure in a polluted soil (300 mg Pb) resulted in a significant decrease in DTPA-extractable-Pb by 11.9 and 23.4 units, respectively. This can be accounted for by the role of organic and inorganic fractions of cow manure in decreasing soil Pb availability. Interactions between Fe and Pb appear to influence the soil Pb availability as application of 15 and 30 t ha-1 converter sludge-enriched cow manure in 300 mg Pb-polluted soil caused a significant decline in soil Pb availability by 10.4 and 9.3 units, respectively. The highest and least root Pb concentration were observed in the polluted soil (400 mg Pb) without applying cow manure and the polluted soil (200 mg Pb) treated with 30 t ha-1 enriched cow manure, respectively. The corn root Pb concentration in unpolluted soils was not detectable by AAS. Applying 5% (W/W) pure Fe from converter sludge in the polluted soil (300 and 400 mg Pb) which were not manured significantly decreased the root Pb concentration by 19 and 9 units, respectively which is explainable by the interaction existing between Pb and Fe in soil. Furthermore, root Pb concentration was affected by converter sludge enriched-cow manure as applying 15 and 30 t ha-1 converter sludge cow manure in a polluted soil (400 mg Pb) significantly decreased the root Pb concentration by 20.8 and 10.9 units, respectively. However, the role of cow manure in increasing pH and decreasing root Pb concentration cannot be ignored. The greatest and least shoot Pb concentration was obtained for the polluted soil (400 mg Pb) without applying cow manure and the polluted soil (200 mg Pb) treated with 30 t ha-1 enriched cow manure, respectively. The corn shoot Pb concentration in unpolluted soils was not detectable by atomic absorption spectroscopy (AAS). Interaction effects were also observed for shoot Pb concentration as using 5% (W/W) pure Fe from converter sludge in the polluted soil (300 and 400 mg Pb) which were not treated by cow manure significantly decreased the shoot Pb concentration by 4.1 and 4.7 units, respectively.
Conclusion: The results of this study showed that interactions between Pb and Fe seem to play an important role in reducing root and shoot Pb concentration. On the other hand, applying cow manure can increase the soil sorption properties such as CEC and decrease the soil Pb availability and plant Pb uptake which is explainable by the fact that the organic and inorganic fractions of manure impact the Pb availability. However, the influences of soil physico-chemical properties such as pH upon soil Pb availability should be taken into account.
Anahid Salmanpour; Mohammad hasan Salehi; jahangard mohammadi
Abstract
Introduction: The heavy metal concentration in agricultural lands, due to the toxicity, persistence and their accumulation in the environment has become a major concern. Ophiolitic formations extend in southern part of central Iran and parallel to folds of the Zagros Mountains, is located in the north ...
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Introduction: The heavy metal concentration in agricultural lands, due to the toxicity, persistence and their accumulation in the environment has become a major concern. Ophiolitic formations extend in southern part of central Iran and parallel to folds of the Zagros Mountains, is located in the north of Neyriz town and in the west of Bakhtegan Lake. Rock weathering of these complexes forms sediments and soils with a large amount of Mn, Ni, Cr, Co, Mg and Fe. Laboratory analysis of Neyriz ophiolitic rocks indicates that they are a source of heavy metals as well, and may cause problems for the environment. However, there is no investigation in Neyriz area regarding contamination of the soils. The present study was conducted to assess soils pollution in Ghal-e Bahman area, 20 km from Neyriz which derived from ophiolitic formations of this area.
Materials and Methods: The study area located in the Ghal-e Bahman region, eastern part of Bakhtegan Lake. The soils of this region are affected from Neyriz ophiolite. In this region, three physiographic units including a hill, an alluvial fan and a lowland (playa) were separated. In each unit, some pedons were dug and classified according to American Soil Taxonomy. Soil samples were obtained from each genetic horizon and rock samples were also taken from ophiolitic formation. Then, chemical and physical properties were determined. Heavy metals were also extracted by nitric acid and amount of Cr, Ni, Co and Fe were calculated. Enrichment Factor (EF) and Geo-accumulation indices (Igeo) were also calculated and soils were classified according to their pollution level.
Results and Discussion: In general, soils on different landforms had different horizon properties and different classification. They are varied from a shallow, thin layer on hills to relative deep layer on lowland. These soils were classified in three different subgroups according to American Soil Taxonomy. Soils on ophiolitic hills classified as Lithic Torriothents because of a thin surface layer on a weathered bedrock. Soils developed on alluvial fan landform, with several alluvial subsurface horizons with different rock fragments percentage and size, was classified as Typic Torrifluvents; and the soils on lowland (Bakhtegan playa (was Gypsic Aquisalids because of salt and gypsum concentration in all layers and had redox color (chroma of less than 2) affected by high level of groundwater in the soil surface and subsurface layers.
The results showed that the amount of chromium with the average of 2200 mgkg-1, was 10 to 40 times higher than the Iran and Europe threshold levels (100 and 150 mgkg-1, respectively). The amount of nickel, with the average of 300 mgkg-1,were 10 fold higher than the threshold level and cobalt (19 mgkg-1) was lower than criteria defined by soils standards of Iran and Europe (40 mgkg-1).The amount of studied metals were the highest in ophiolitic hills, and playa soils were in second place in this respect. The amount of metals had a significant decrease in alluvial fan but didn’t drop under threshold level. The lowest amount of heavy metals in alluvial fan was probably because of the high percentage of sand, higher permeability and low soil water retention in all horizons. The negative significant correlation between the elements and sand also confirms this hypothesis. In addition, increasing elements at the depth of 70 cm of the soil in alluvial fan showed that land type (orchards) and long period of irrigation may cause leaching heavy metals from topsoil to the soil depth. However, no significance correlation was observed between the elements and soil organic carbon. The correlation coefficients between three elements revealed that all of them had the similar geologic origin and thus their spatial occurrence in soils can be attributed to the weathering of similar parent material.
Igeo showed an almost constant trend from ophiolitic hill (7.7-7.8) to alluvial fan (7.2-7.7) and a significant decrease in playa (3.9-6.2) for all metals. The variation of EF for nickel had an almost constant trend from ophiolitic hill (with the average of 0.6) to alluvial fan (with the average of 0.7) and a significant decrease in playa (with the average of 0.1). Also, a decreasing trend was observed from ophiolite hill (0.9 and 0.6 for chromium and cobalt, respectively) to alluvial fan (0.5 for both) and playa (0.3 and 0.1 for chromium and cobalt, respectively). A decreasing trend observed for indices can be due to the reduction of sediment transport processes and dilution effect of elements from hill to playa during the deposition and their formation .It seems that the EF index and the Igeo provide more useful information about hydrologic processes during formation of landform and development of soils than absolute values of heavy metals.
Conclusions: The present study showed that the amounts of chromium and nickel were higher than the threshold in studied soil. The soils derived from ophiolitic formation showed the highest values and the soils over alluvial fans had the lowest levels of heavy metals. Useful information was obtained from EF index and Igeo about the prominent geomorphic processes during landforms formation
Future studies should be focused on possible transfer of these elements into the groundwater and also trees of the orchards in Ghal-e Bahman region.
habib beigi; S. Ahmadzadeh; S. Heshmati
Abstract
Introduction: Soil pollution, i.e. elevated concentration of undesirable organic and inorganic matter such as trace elements higher than natural background concentration can be a consequence of indirect or intentional human activities. Evaluation of the effect of the agricultural operations and particularly ...
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Introduction: Soil pollution, i.e. elevated concentration of undesirable organic and inorganic matter such as trace elements higher than natural background concentration can be a consequence of indirect or intentional human activities. Evaluation of the effect of the agricultural operations and particularly using the wastewater on soil trace element concentrations is useful and required to manage the land and reduce the health risks of the food products. The aims of this study were: [1] The estimation of the mean concentration and max limit of the background concentration for Cd, Cr, Ni, Pb, Co and Hg in the surface soil samples of Boroujen-Faradonbeh plain; and [2] Evaluation of the effect of agricultural operation and farming by non-conventional water on background concentration and on accumulation, distribution and pollution load of the soil of this plain.
Materials and Methods: Boroujen-Faradonbeh is an agricultural plain loaced in the Chaharmahal and Bakhtiari mountainous province of Iran. Two hundered surface soil samples (0-20 cm) were taken from three types of land: never-uncultivated soil (20 samples), freshwater-irrigated (90 samples) and wastewater-irrigated (90 samples) soils. The total sampled area was about 2340 hectares. The exact position of the samples were recoded using a GPS device. The total concentrations of Pb, Co, Ni, Cd, Cr and Hg in the samples, and the background and upper limit concentrations were determined. In addition, pollution loading index (PLI) for the whole plain determined and delineated. To separate the affects of agricultural practices and wastewater application the analysis of variance of StatSoft Statistica 12 was used. Maping, and related operations were conducted inside ArcGIS 9.3.
Results and Discussion: Background concentrations of Ni, Cd, Cr, Hg, Co, and Pb, were determined as 1.13, 0.16, 1.56, 0.09, 0.80, and 1.52 mg/kg, respectively; while upper limit concentrations for the mentioned trace elements were respectively 1.3, 0.28, 1.6, 0.16, 0.9, 1.7 mg/kg. Conventional farming (application of fertilizer but not wastewater) increased the soil accumulation factor of Cd and Pb to 1.7 and 1.9 (p
tahereh mansouri; Ahmad Golchin; Mohammad Babaakbari
Abstract
Introduction: Arsenic (As) is the twentieth element in earth's crust and the contamination of soils and ground waters by it is common and disturbing. In addition to geological factors and soil parent material, human activities such as mining and smelting, coal combustion and the use of arsenic-containing ...
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Introduction: Arsenic (As) is the twentieth element in earth's crust and the contamination of soils and ground waters by it is common and disturbing. In addition to geological factors and soil parent material, human activities such as mining and smelting, coal combustion and the use of arsenic-containing compounds such as insecticides, pesticides, wood preservations and etc lead to the accumulation of high levels of this metal in the soils. Long-term exposure to As can lead to skin, bladder, lung, and prostate cancers.The presence of As in soil and water causes its transfer to different parts of the plant. Because of the crucial role of corn in human nutrition, investigation of the uptake, transport and accumulation of As in different parts of this plant is very important, thus this study was carried out with the aims of evaluating the response of corn to the presence of As in the environment and its impact on concentrations of phosphorus (P), iron (Fe), zinc (Zn) and manganese (Mn) in this plant.
Materials and Methods: Soil samples were collected and after air drying, passed through a 2 mm sieve and analyzed for some physico-chemical properties. The samples were then artificially contaminated by different levels of arsenic (0, 6, 12, 24, 48 and 96 mg/kg) using Na2HAsO4.7H2O salt and incubated for 6 months, and then planted to corn. Before planting, the concentration of available As was determined. At the end of growth period, mean height of plants was measured and then the above and below ground parts of plants were harvested, washed, dried and digested using a mixture of HNO3 and H2O2. The concentrations of As, P, Fe, Zn and Mn in plant extracts were measured. Statistical analyses of data were performed using SAS software and comparison of means carried out using Duncan's multiple range test.
Results and Discussion: The results indicated that As concentration increased both in root and in shoot with increasing As concentration. The highest As concentrations in corn root and shoot were 383.41 and 59.56 mg/kg, respectively. Arsenic accumulation in root was higher than the shoot, so that the concentrations of arsenic in the roots of plants grown at 6, 12, 24, 48 and 96 mg As/ kg of soil, were 1.88, 1.99, 3.13, 4.96 and 6.44 times higher than their concentrations in shoot, respectively. Corn was sensitive to As stress and growth of it reduced by increasing the level of soil As. Mean heights of plants grown in soils polluted with 6, 12, 24, 48 and 96 mg As/kg decreased compared to control by 10.74, 25.30, 38.99, 59.71 and 76.66%, respectively. The rate of reduction of dry weights of roots of plants grown in soils polluted with 6, 12, 24, 48 and 96 mg As/kg were 10.66, 30.20, 54.64, 81.65, 95.94 % and ones of shoot were 11.30, 27.25, 47.14, 77.66 and 95.22%, respectively, which showed corn root was more sensitive to As than shoot. Arsenic uptake by root and shoot increased with increasing the As levels to 48 and 24 mg/kg, respectively, but at higher levels of As it decreased, this showed that up to these levels, increasing arsenic concentrations in plant parts surpassed from the decreasing dry weights of them and the amount of uptake obtained by multiplying these two factors, increased. Phosphorus concentrations in root and shoot increased and decreased, respectively, with increasing soil As concentration, and this matter showed As reduced P translocation from the root to the shoot of plants. Iron and Zinc concentrations in root and shoot decreased but Manganese concentration increased with increasing soil As concentration.
Conclusions: The results of this study showed that the corn plant is very sensitive to arsenic and its growth decreased even in the presence of low concentrations of arsenic. Arsenic accumulation in root was higher than the shoot. Arsenic changed the concentration of nutrients in the soil and the corn, So that increased the available P concentration and reduced the available concentrations Fe, Zn and Mn. It also reduced the translocation of P, the concentration of Fe and Zn in the root and shoot. The statement that toxicity limits plant As uptake to safe levels was not confirmed in our study. If corn plants are exposed to a large concentration of As, they may accumulate residues which are unacceptable for animal and human consumption.
Nasrin Ansari; Mehdi Hassanshahian; MohammadReza Khoshro
Abstract
Introduction: Petroleum hydrocarbons are widespread pollutant that enters to soil by some pathwayssuch as: Transportation of crude oil, conservation of oil compounds, crude oil spill and treatment process on refineries. Oil pollution has some ecological effect on soil that disturbed composition and ...
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Introduction: Petroleum hydrocarbons are widespread pollutant that enters to soil by some pathwayssuch as: Transportation of crude oil, conservation of oil compounds, crude oil spill and treatment process on refineries. Oil pollution has some ecological effect on soil that disturbed composition and diversity of microbial community. Also this pollution has some effects on microbial activity and enzymes of soil. Forests ecosystems may be polluted with petroleum hydrocarbons via different ways such as transportation and spill of crude oil from resource of petroleum storage. Industrial soil defined as the soils that located in industrial area such as petrochemical plant, mine, chemical factories and etc. These soils always contaminated to many pollutant such as: oil, diesel and heavy metals. These pollutants have some effects on the texture of the soil and microbial community. The aim of this research is to understand the effect of oil pollution on two different soils.
Material and Methods: In order to evaluate the effect of crude oil on soil microbial community, two different soil samples were collected from industrial and forest soils. Six microcosms were designed in this experiment. Indeed each soil sample examined inthree microcosms asunpolluted microcosm, polluted microcosm, and polluted microcosm with nutrient supply of Nitrogen and PhosphorusSome factors were assayed in each microcosm during 120 days of experiment. The included study factors were: total heterotrophic bacteria, total crude oil degrading bacteria, dehydrogenase enzyme and crude oil biodegradation. For enumeration of heterotrophic bacteria nutrient agar medium was used. In this method serial dilutions were done from each soil and spread on nutrient agar medium then different colonies were counted. For enumeration of degrading bacteria Bushnel-Hass (BH) medium were used. The composition of this medium was (g/lit): 1 gr KH2PO4, 1gr K2HPO4, 0.2 gr MgSO4.7H2O, 0.02 gr CaCl2, 1 gr NH4NO3, and two drops of FeCl3 60% , the pH was 7. The carbon source of this medium was crude oil (1%). In MPN method microplates (24 well) were utilized and turbidity was calculated as positive index.
Results and Discussion: The results of this study showed that the highest quantity of heterotrophic bacteria was related to forest soil (8 × 108). The quantities of degradative bacteria significantly were lower than heterotrophic bacteria in all soil microcosms. This result may be expected because heterotrophic bacteria can use other carbon sources instead of crude oil such as organic carbon, suger and some nutrients that exist in the soil, but degrading bacteria have some limit in the use of organic carbons and only capable to use crude oil hydrocarbons. Sothe quantity of these bacteria is lower than heterotrophic bacteria. The quantity of degradative bacteria have decrement pattern until 60th day of experiment but after this day these bacteria have increment pattern. This result can be interpreted as from beginning of experiment until 60th day of experiment the bacteria adapted to toxic effect of crude oil and after this time the quantity of bacteria increased and have ability to use pollutant in the soil. The best deydrogenase activity between different microcosms related to polluted microcosm with nutrient. This result confirms that nitrogen and phosphorus can decrease the damage effect of crude oil on soil microbial community. The mechanism of this attenuation of toxicity effect of crude oil on microbial community can be related to enhance bioavailability of essential elements for bacteria in the soil. So after oil pollution of an area, soil supply upto nitrogen and phosphorus demand must be mentioned as a necessary practice to decrease the toxicity effect of pollutants. The highest biodegradation of crude oil in all studied soils belonged to industrial microcosm (95 %). It can be explained by adaptation theory because the bacteria in the industrial soil were better adapted to different pollutants and these bacteria have more capability for biodegradation of crude oil. By this reasonthe rate of degradation of crude oil in the industrial soil were higher than forest soil. Statistical analysis of the results showed that there was a significant correlation between MPN quantity of heterotrophic bacteria and other assayed factors. Also, forest soil seemed to have significant difference with other soils.
Conclusion: according to the obtained results by this study, it can be possibly proposed appropriate strategies for bioremediation of different studied soil types. The selection of best bioremediation strategies belong to specific types of soil. Just as this research confirmed that the type of soil plays significant role in the percentage of degradation.
Nastaran Esmaeilpourfard; J. Givi; A. Davodian
Abstract
Introduction Due to mining, considerable amounts of heavy metal bearing mineralsare scattered in the atmosphere in the form of dust and make the surrounding air, water and soils polluted.Runoff water movingfrom the mountainstowardsplains may also transport heavy metals from mines to the soils.One type ...
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Introduction Due to mining, considerable amounts of heavy metal bearing mineralsare scattered in the atmosphere in the form of dust and make the surrounding air, water and soils polluted.Runoff water movingfrom the mountainstowardsplains may also transport heavy metals from mines to the soils.One type ofpollutions is contamination withheavy metals.The purpose of the present research has been to investigate the effect of heavy metals of mine on soil, water, plant and dust pollution.
Materials and Methods: Gushfil mine is located 3 kilometers southwest of Sepahanshahr, Isfahan. Soil profiles were dug 500 meters apart along three parallel transects, between east of Sepahanshahr and Gushfil mine. The profiles were described and samples were collected from their horizons. Ore, wells, plant and dust were sampled as well. Total concentrations of lead, zinc and cadmium were measured in the samples. To find the origin of polluted dust and soil, lead isotopes contents in the samples were measured and regressional relationships between the ratios of these contents were investigated.
Results and Discussion Sepahanshahr soils are not contaminated by zinc, lead and cadmium, but within a distance of one to two kilometers from the Gushfil mine, the soils are polluted by zinc and lead. Cadmium contamination was not observed in the studied soils. In all of the soils, the heavy metals content varies downwards irregularly. The reason for this variation trend is that the studied soils are alluvial. In different periods of time, alluvium parent materials have been transported by runoff water from the lead and zinc mines towards the alluvial piedmont plain. The studied heavy metals have been distributed irregularly in different horizons of the soils that have been formed in these parent materials. Lead and cadmium concentrations of drinking water in the studied area are much higher than the maximum amount allowed by the World Health Organization. Cadmium content in all trees of the Sepahanshahr urban park and in alfalfa, lead content in olive trees and lead and cadmium concentrations in Holly hock (Althaea officinalis), Spurge (Euphorbiarigida) and Rhizome (Acanthe phylum bracteatum)are higher than dietaryallowance. Significant correlation between heavy metal concentrations reduction in dust samples and increase of distance from the mine expresses that contaminant heavy metals enter the atmosphere due to mine explosions. In dolomitic sandstone rich in sphalerite mineral, the total amounts of lead and zinc are maximum. The maximum amount of cadmium and too much lead and zinc were observed in a shale fragment, sampled from a location of a fault in the mine. Contents of the three metals were less in black and green shales, compared with the other samples. In dolomitic sandstone rich in gallon mineral, the amounts of the three metals are high and its lead content is maximum with respect to other rocks excluding dolomitic sandstone rich in sphalerite mineral. Significant correlation between ratios of lead isotopes contents of the rocks, soil and dust showed that the soils of the alluvial piedmont plain located at the footslope of the western mountains of the studied area have formed in alluvium parent materials originated from western mountains. The studied heavy metals have been transported together with these alluviums from the mine towards the alluvial piedmont plain. The other origin of these metals is the dust which is produced during the Gushfil mine explosions. This dust is translocated towards the Sepahanshahr and makes the surrounding environment of the mine polluted.
Conclusions: Origin of zinc, lead and cadmium in soil, water, plant and dust in the studied area is rocks of Gushfil mine. Transportation of these metals from the mine towards the environment can be explained by two mechanisms: 1) together with runoff water flowing from the western mountains towards the alluvial piedmont plain and 2) in the form of dust which originates from the mine and moves eastwards. The soils are not contaminated with cadmium. With increase of distance from the mine, contamination of lead and zinc decreases in soil and dust in such a way that in the Sepahanshahr soils, pollution of these metals is not observed. The soils located within a distance of 1 to 2 kilometers from the Gushfil mine are contaminated with lead and zinc. Water is polluted with lead and cadmium and the cadmium content of the plants is higher than dietaryallowance.
Sh. Nosratipoor; M. Nael; Mohsen Sheklabadi; A.A. Sepahi Garo
Abstract
To determine the origin of heavy metals, the effects of parent materials, soil genesis, and human activities on the content and distribution of selected metals in soils near Mofateh Martyr powerhouse, Hamedan, were assessed. Six types of parent materials including shale, schist, limestone, alluvial ...
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To determine the origin of heavy metals, the effects of parent materials, soil genesis, and human activities on the content and distribution of selected metals in soils near Mofateh Martyr powerhouse, Hamedan, were assessed. Six types of parent materials including shale, schist, limestone, alluvial plain, alluvial terraces and fan deposits were identified and soil genesis were studied. Total content of Cd, Cu, Mn, Ni, Zn, Pb, Fe were determined in soil horizons and parent materials. Concentration of the metals in four different chemical phases, including acetic acid extractable, reducible, oxidizable and residual fractions, was determined with four-step sequential extraction procedure. Soil development is limited in the studied region so that the discrepancy between solum and parent material in terms of heavy metal content is not great in general. Calcareous soils and limestone have the lowest amount of copper, manganese, nickel, zinc, lead and iron. Independent of soil types and parent materials, most of the heavy metals, except Mn, were present in the residual fraction. The concentration of Mn in all profiles is highest in reducible fraction. Low degree of soil development and the prevalent presence of metals in residual fraction show the influential role of parent materials in controlling metal concentration and distribution; pedogenic processes have minor effects. The role of human activities is limited for most of the selected metals; however, the tangible presence of Pb and, in some cases, Cd in acetic acid extractable fraction, reflects the impact of human activities on the concentrations of these two metals.
Abstract
In many areas, the main source of surface and groundwater nitrogen pollution is agriculture and simulation models are useful tools in determining the contribution of nitrogen produced by agriculture in pollution of water resources. In this research, leaching of nitrate on a loam-silty to loam soil was ...
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In many areas, the main source of surface and groundwater nitrogen pollution is agriculture and simulation models are useful tools in determining the contribution of nitrogen produced by agriculture in pollution of water resources. In this research, leaching of nitrate on a loam-silty to loam soil was measured and simulated using LEACHN model after calibration. The experimental design was complete randomize block. The planting media consist of 15 PVC lysimeters (soil column) with 40 cm diameter and 120 cm height. In these lysimeters, maize (Singel Cross 704) was planted. The nitrogen treatments were 0.0 (control), 150, 200, 250 and 300 kg N/ha as urea with three replications. The results were showed that at 120 cm soil depth and the end of growing season, the nitrate leachate in 150, 200, 250, and 300 kg ha-1 treatments were increased 132, 174, 134 and 182% relative to control, respectively. Comparison between the measured and simulated results showed that LEACHN overestimated the leached nitrate in drainage water with the relative error between 11.3% (300 kg ha-1 treatment) and 88.6% (control). The order of accuracy in simulations was obtained in 300, 200,150 and 250 kg ha-1, respectively. In general, the evaluation of LEACHN model showed that the accuracy of this model for simulation of nitrate leachate was relatively good.
Gh. Rahimi; A. A. Charkhabi
Abstract
The paddy soils in Lenjan area exposed to pollution owing to uncontrolled discharge of sewage sludge, wastewater and unessential fertilizers. Little information exists on Cadmium (Cd) distribution in paddy soils of Isfahan Province, this study was therefore investigated the spatial variability of cadmium ...
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The paddy soils in Lenjan area exposed to pollution owing to uncontrolled discharge of sewage sludge, wastewater and unessential fertilizers. Little information exists on Cadmium (Cd) distribution in paddy soils of Isfahan Province, this study was therefore investigated the spatial variability of cadmium which is considered as the most toxic metals. 90 soil samples (0-20 cm) were collected from study area. Soil properties such as pH, EC, calcium carbonate equivalent, soil texture, organic matter and cation exchange capacity were measured. The total and available Cd concentrations of soil samples analyzed by atomic absorption spectrophotometer. In addition, estimation of spatial data performed via kriging interpolation method (ordinary and blocky kriging) and by GIS. The total and available concentration of Cd in the study area were averagely 1.747 and 0.073 mgkg-1 respectively, which were much higher than the standard limit and classified in high pollution. Geostatistical analysis result was shown that exponential and spherical models for the total and available Cd concentration were best model, respectively. The most effective range of total and available Cd was 1011 and 1050 meter respectively and correlation ratio was weak in this range. Evaluation of correlation coefficient, MEE and RMSE parameters showed that both methods of kriging for data estimation in comparison with real data had acted in an appropriate manner. The result also showed that human activities such as industrial and urban wastewater entering to the water resources and application of excessive fertilizers had an impact on cadmium concentrations significantly.
