salar rezapour; H. Azhah
Abstract
Introduction: Human activities such as intensive cultivation and land use changes alter nutrients fluxes (mainly iron) and mineralogy in soil and terrestrial ecosystems. Iron is an essential element for plants and microorganisms and its solubility is controlled by stable hydroxides, oxyhydroxides, and ...
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Introduction: Human activities such as intensive cultivation and land use changes alter nutrients fluxes (mainly iron) and mineralogy in soil and terrestrial ecosystems. Iron is an essential element for plants and microorganisms and its solubility is controlled by stable hydroxides, oxyhydroxides, and oxides. In general, parent material, climate, and landscape position are the major factors that accelerate the weathering of the minerals and rocks containing Fe in the regional scale. However, long-term cultivation and intensified agriculture may be the dominant attributes of modifications in soil properties like Fe compounds mainly in arid and semiarid regions, where the irrigational and agricultural practice is current over long-term periods. Although substantial data is documented on Vertisols properties, few studies are available to assess the effects of long-term continuous cultivation on the characteristic and distribution of iron oxides and their mineralogy, mainly in calcareous environments.
Materials and Methods: This study was conducted in the Piranshahr - Pasvah area (36° 46 to 36° 50 N and 45° 09 to 45° 50 E, 1500 m above sea level), West Azarbaijan Province, northwest of Iran. Six soil profiles belonging to three subgroups of Vertisols order (Chromic Calcixererts, Typic Haploxererts, and Typic Calcixererts) were described and sampled from the cultivated soils and similar soils from the nearby uncultivated region as grassland. Soil samples were air-dried and passed through a 2-mm mesh sieve before the analysis. Soil analysis included particle-size distribution, pH and electrical conductivity (EC), soil organic carbon (SOC), calcium carbonate equivalent (CCE), cation exchange capacity (CEC), the determination of iron oxides forms and mineralogical composition. Free or pedogenic Fe oxides (Fed) including crystalline, poorly crystalline, and organically bound Fe were extracted by dithionite–citrate–bicarbonate (DCB) method. Poorly crystalline and organically bound Fe (Feo) were extracted using 0.2 M ammonium oxalate (AO). Organic complex of Fe (Fep) was extracted by 0.1 M Na-pyrophosphate at pH 10. All Fe oxide forms were determined using atomic absorption spectrometry. The difference between DCB-Fe and AO-Fe was considered as an estimation of crystalline Fe oxides form.
Results and Discussion: The results showed that long-term cropping caused a considerable drop in organic carbon and calcium carbonates along with a noticeable rise in the values of clay and cation exchange capacity as a result of accelerated alteration by farming activities and interactions between the used irrigation water and soils receiving it. Long-term cultivation improved the amount of Fed and Fecry (crystalline Fe) from 1 to 64% and 44 to 90%, respectively, than those of uncultivated soils which can be explained in some pathways: (1) accelerated weathering of Fe-bearing minerals (such as biotite, chlorite, feldspars, amphibole, and pyroxene) in the cultivated soils and (2) the higher temperature condition and the more number of wetting–drying cycles in the cultivated soils compared to the uncultivated soils. Despite the fact that long-term cultivation caused a significant decrease in organic matter, a pronounced increase in organic complex of Fe with the range of 19 to 61% was recorded with farming practices. Such pattern can be contributed to the chemistry of organic matter and the presence of more stable fraction (passive fraction) of soil organic matter in the cultivated soils. The XRD patterns of primary Fe-bearing minerals (such as amphibole, pyroxene, and feldspar) had less intense in the cultivated soils compared to those of the adjacent uncultivated soils, indicating that probably cultivation promoted the instability and weatherability of Fe-bearing minerals as well as the loss of Fe from the minerals. In contrast, the X-ray reflections of secondary Fe-oxide minerals such goethite appeared to be higher, sharper and intense by long-term cropping, suggesting that agricultural practices also promoted the crystallization of the soil Fe oxides. Compared to the uncultivated soils, long-term agricultural practices caused some changes in X-ray reflections of chlorite, illite, and smectite.
Conclusions: The results showed that the weathering of Fe-bearing minerals and layer silicates, as well as the production of Fe oxide forms were promoted under long-term continuous cropping. Under cultivation, a pronounced increase in Fe-oxide forms, particularly Fed and Fecry, was recorded for the most of the examined soils which can be associated with the combined effects of increased soil temperature and moisture content from irrigation and farming practices. As emphasized, the combined effects of increased compounds from agricultural input (such as chemical and organic fertilizers, the compound of irrigation water, and moldboard tillage) as well as increased precipitation from irrigation interacted to create conditions for: (1) more intense the weathering of Fe-bearing minerals and (2) the more production of iron oxides forms in the cultivated soils.
behnaz atashpaz; salar rezapour; Nader Gaemian
Abstract
Introduction: Over the past decades, due to climate change and water scarcity, the recovery and use of urban wastewater, especially in arid and semi-arid climates, has increased. But since wastewater is considered as an unconventional source of water, its use in agriculture requires special management ...
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Introduction: Over the past decades, due to climate change and water scarcity, the recovery and use of urban wastewater, especially in arid and semi-arid climates, has increased. But since wastewater is considered as an unconventional source of water, its use in agriculture requires special management which, while benefiting from it, does not have environmental and health hazards in soil, plant and surface water and underground water resources. On the other hand, sewage systems often have significant amounts of heavy and toxic metals, the type and amount of which varies from place to place, and even in the specific location, over time. The soil also has a limited capacity to absorb and maintain these elements, and if their concentration exceeds the permitted range, they can cause pollution of the water, soil, plant and human cycle. Therefore, the present study was conducted to investigate the effect of irrigation with treated wastewater in Urmia city on concentrations, distribution and contamination of Zn, Cu, Cd, Pb and Ni elements.
Materials and Methods: In field work, 6 soil profiles (5 profiles from the wastewater-irrigated soils and a profile from the well-irrigated soil as control soil) were dug, described, and sampled. At around each profile, composite soil samples were also obtained in the root depth of the area (Ap horizon, the depth of 30 cm). Soil samples were first air-dried and passed through a 2-mm sieve and then analyzed for the determination of heavy metals. The available and total fraction of zinc (Zn), copper (Cu), cadmium (Cd), leads (Pb), and nickel (Ni) were extracted by DTPA method and concentrated acid (HNO3) procedure, respectively. The content of Zn, Cu, Cd, Pb and Ni were determined by an atomic absorption spectrophotometer (Shimadzu AA-6300). Descriptive statistics were conducted using SPSS 16 for Windows. In order to study the effect of irrigation with treated wastewater on the extent of contamination of heavy metals, the AP (availability percentage), PI (Single-factor pollution index), NPI (Nemerows pollution index), and PLI (Pollution load index) in the affected soils with this wastewater was calculated. Also, all soil and water experiments were performed in 3 replicates and then, using the excel data software category, tables and charts were plotted.
Results and Discussion: The soils were alkaline and calcareous as characterized by high pH, ranging from 7.6 to 8, and calcium carbonate equivalent, ranging from 30 to 42%. On average, the value of the available fraction of the examined metals in the wastewater-irrigated soils ranged from 1.9 to 3.5 mg kg-1for Zn, 2.5- to 3.5 mg kg-1for Cu, 0.4 to 0.62 mg kg-1for Cd, 2 to 2.9 mg kg-1for Pb, and 1.34 to 1.75 mg kg-1for Ni. Comparing to the control, irrigation with wastewater resulted in a considerable build-up in the available fraction of the metals in the rank of Ni (79-142%)> Cd (54-125%)> Zn (35-73%)> Cu (13-87%)>Pb (6-32%). These patterns can be due to the quality and quantity of the used wastewater and impact of the used wastewater with its receiving soils. Similar to the available fraction, there was an increasing trend in the total fraction of metals in the order of Cd> Zn>Pb> Ni> Cu following wastewater irrigation. In this context, the mean content of total Zn, Cu, Cd, Pb, and Ni in wastewater-irrigated soils was as 51-157%, 10-32%, 243-310, 11-203%, and 13-126% higher than those of control soil, respectively. In spite of such enrichment, only the Cd values exceeded the maximum acceptable limits. The AP index is an appropriate index to compare the mobility potential and the toxicity of heavy metals in soil. In this study, the highest rate of this index among the heavy metals was related to Cd and its lowest level was related to Pb, which showed more toxicity and more mobility of Cd compared with other elements. The average of single-factor pollution index of five elements was observed in sequence Cd> Zn> Ni>Pb> Cu that the element of Cd had the highest class of PI (class 4). The highest and lowest of NPI values of five elements were observed in profiles 4 and 2, respectively. Also, the greatest effect of the five elements of this study is on the elements of Cd and Zn in the generation of this level of contamination. The pollution index of the five studied elements in irrigated soils with treated wastewater was similar to the NPI, its maximum was observed in profile 4 and Cd showed the highest effect on increasing the value of this index.
Conclusions: The results of this study showed that irrigation with sewage significantly increased the available fraction of the metals in the order of Ni (78.9-141.8%)> Cd (54.4-125%)> Zn (35.7-73.3%>Cu (13-87%)>Pb (6-32.3%) compared to the control. However, with the exception of cadmium, the available fraction of other elements was within the permissible limit. Compared to the control, in the majority of studied soils, the total fraction of the metals (with the exception of copper) was significantly increased and the lowest and highest increase associated with Cu (10-32%) and Cd (2 - 3 times). Also, the results of pollutant indices showed that the majority of the studied soils were in the low to high contamination and Cd was known as the major metal affecting the indices yield.
zahra amirpour; salar rezapour; behnam dovlati
Abstract
Introduction: Multiple biological and physiological processes in the plant, including carbohydrates and proteins formation, activation of 50 enzymes for energy transmission as well as reducing water losses from leaf pores, are mostly affected by the presence of potassium in the plant. In order to test ...
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Introduction: Multiple biological and physiological processes in the plant, including carbohydrates and proteins formation, activation of 50 enzymes for energy transmission as well as reducing water losses from leaf pores, are mostly affected by the presence of potassium in the plant. In order to test this hypothesis, five soil subgroups (TypicCalcixerepts, FluventicHaploxerepts, TypicEndoaquepts, TypicHalaquepts and VerticEndoaquepts) belonging 15 series of gardened and adjoining virgin soils were described and sampled. The studied soils had been influenced under horticultural practices for over five decades.
Materials and Methods: The soil samples were analyzed for different K forms, K adsorption and physico- chemical properties after air drying and grinding to pass through a 2 mm-sieve. The particle-size distribution was determined by the hydrometer method (Bouyoucos, 1962). The total carbonate in the soil expressed as the calcium carbonate equivalent (CCE) was determined by a rapid titration method (Nelson, 1982). Organic matter (OM) was measuredby the Walkley and Black (1934) dichromate oxidation method. The pH of the soil was analyzed in 2:1 CaCl2/soil suspension using glass electrode pH meter (Crockford and Norwell, 1956) and EC was detected in a saturated extract. The cation exchange capacity (CEC) was measured using sodium acetate (1 M NaOAc) at pH 8.2 (Chapman, 1965). Water soluble K was extracted with deionized water (1: 5 w/v) after shaking for 30 minutes on a mechanical shaker and later contents were centrifuged to separate clear extract (Jackson 1973). Exchangeable K was determined by extracting the soil with neutral normal ammonium acetate, Non-exchangeable K was estimated as the difference between boiling 1N HNO3 –K and neutral normal ammonium acetate K (Thomas 1982).
Results and Discussion: The result showed that for most of the studied soils, long-terms horticultural practices decreased the amount of different K forms as a result of changes in soils types, agricultural practices and soil properties. In Comparing to the virgin soils, long-term horticultural and irrigation activities caused a decrease?? in soluble K from 0.05 (a drop of 15% with depletion factor of 0.85) to 1.48 mmol l-1(a drop of 95% with depletion factor of 0.05), potassium absorption ratio (PAR) from 0.08 (a drop of 31% with depletion factor of 0.69) to 1.17 mmol l-1(a drop of 97% with depletion factor of 0.03), exchangeable K from 12.01 (a drop of 3% with depletion factor of 0.97) to 285.98 mg kg-1 (a drop of 97% with depletion factor of 0.43),exchangeable potassium percentage(EPP) from 0.49 (a drop of 12% with depletion factor of 0.88) to 3.47% (a drop of 59% with depletion factor of 0.41), available K from10.42 (a drop of 3% with depletion factor of 0.97) to 180.65 mg kg-1(a drop of 53% with depletion factor of 0.47) and non-exchangeable potassium from 43.05 (a drop of 8% with depletion factor of 0.92) to 114.65 mg kg-1 (a drop of 19% with depletion factor of 0.81). Isotherm studies showed that the uptake of potassium in gardened series were more than virgin soils. The highest adsorption values were observed in VerticEndoaquepts (gottape) subgroup.In this series of soil, amount of available k (potassium soluble + exchangeable K) and expandable clay increased by long-term horticultural practices which can be effective in increasing K buffering capacity.
Conclusion: long-term horticultural practices decreased K in soil solution and potassium adsorption ratio. The main reasons for the decline of soluble K can be explained by possible movement of K into the depths, dense cultivation and harvesting crops as well as high levels of calcium and magnesium in irrigation water of study area.In comparison with adjoining virgin soils, horticultural practices caused significant decrease in the amount of exchangeable K, exchangeable K percentage (EPP) and available K. The most important cause of reduced exchangeable potassium may be related toK uptake by apple trees (The study area is generally under the apple orchard user) which had the great need for K. Consequently, due to lack of fertilizers application and agricultural practices,the amount of available K declined in soils about 80percent. On the other hand, In the Non-exchangeable K amount with long-term horticultural practices non- significant reduction occurred. Since the amount of exchangeable and available k in these soils is high, it seems to be enough to satisfy the needs of the regional products.
Arezoo Taghipour; S. Rezapour; B. Dovlati; Roghaie Hamzenejad
Abstract
Introduction: Intensified agriculture over a long-term is an important factor in soil change phenomena that can cause some unwanted effects on soil properties. To examine this hypothesis, chemical properties of the soils under sunflower cultivation over five decades and adjoining virgin lands were investigated ...
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Introduction: Intensified agriculture over a long-term is an important factor in soil change phenomena that can cause some unwanted effects on soil properties. To examine this hypothesis, chemical properties of the soils under sunflower cultivation over five decades and adjoining virgin lands were investigated in order to monitor changes caused by long-term cropping. The studied soils are influenced by continuous sunflower cultivation along with flooding irrigation and using chemical fertilizers for over five decades
Materials and Methods: This research was undertaken at Khoy area (38o 10′ to 38o 40′ N latitude and 44o 15′ to 45o 10′ E latitude) as the northern part of western-Azarbaijan province in the north-west Iran. The Khoy area is characterized by a semi-arid climate (mean annual rainfall of 300 mm) linked with soil moisture and temperature regimes of xeric and mesic, respectively. Agriculturally, the studied area is cropped continuously by sunflower-wheat or barley rotations for over five decades and has received irrigation water from rainfall, groundwater, or seasonal river water. Forty soil surface samples (0-30 cm) belonging to 10 soil series from the cultivated soils and the adjoining uncultivated soils were samplied and analyzed for the different chemical properties. In each soil serie, the samples (cultivated soil and adjacent virgin land) were selected in similar slope, aspect, drainage condition, and parent materials. Soil analyses were involved soil pH and electrical conductivity (EC), soil organic carbon (SOC), Calcium carbonate equivalent (CCE), cation exchange capacity (CEC), total N, soluble K, exchangeable K, and available K. Potassium absorption ration (PAR) was calculated by the concentration of solution K, Ca, Mg and exchangeable potassium percentage (EPP) was calculated by exchangeable Na and CEC values
Results and Discussion: This study illustrate that long-term continuous sunflower cropping had considerable effects on some soil chemical attributes. Over five decades of cultivation, a depletion face was observed in soil organic carbon, CCE, and some K forms (solution, exchangeable, available K) for most of the studied soils. In contrast, an enrichment aspect was occurred in the values of EC. The results showed that soil pH and calcium carbonate equivalent were increased by 0.09 – 0.39 units and 16 – 26 g.kg-1, respectively, in most of the examined soils after intensive agricultural practice. Increase in the CCE value may be caused by tillage operation because of the calcareous parent material is tilled periodically by farmers to cultivate a certain depth of soil in the studied soils. Compared to the uncultivated soils, the cultivated soils showed a relative enrichment in electrical conductivity (20 – 80%) which could be attributed to the chemistry of the irrigation water used and the interaction between the irrigation water and its receiving soils. A slight decline was observed in soil CEC values (1 – 9%) probably due to destruction of soil organic matter. There was a decreasing pattern in the content of soil organic carbon with cultivation ranging 17 to 39% which could be associated with the environmental conditions and management practices, i.e. (a) in the cultivated soils much of plant residues is removed or burned after harvest, (b) the present of livestock after harvest which can result in a substantial loss of SOC, (c) breaks up, decomposition, and mineralization of organic matter is accelerated by tillage practices, (d) the relatively high temperature in the cultivated soils compared to the uncultivated soils which might enhance oxidation of organic matter and destroying of organic C. A relative depletion was observed in the mean value of soluble K (10 – 330%), exchangeable K (25 -40%), available K (16 – 41%), potassium absorption ratio (16 – 61%), and exchangeable potassium percentage (26 – 40%) following continuous sunflower cropping mainly as removal of most sunflower residues after harvest and high uptake of K by sunflower as a high –K- requiring crop. In spite of the fact that exchangeable and available K declined by cropping for most of the studied soils, the soils were grouped as optimal to high category based on two the K forms. This means that intensive rotation cropping not be able to deplete soil exchangeable and available K below a certain level manly due to the presence of the high levels of K-bearing minerals.
Conclusion: Overall, the chemical properties of different soil series reflected different responses to (both increasing and decreasing pattern) long-term sunflower cultivation. Organic carbon, soluble and exchangeable K along with EC was known to be the most sensitive indicators following long-term continuous sunflower cropping and irrigation practices. In this cause, it seems hat monitoring the chemical characteristics of both the irrigation water and the soil must be considered in order to establish the water –soil-plant management strategies that will help to prevent environmental degradation and to maintain the overall heath of the studied soils.
R. Hamzenejad Taghlidabad; H. Khodaverdiloo; Sh. Manafi; S. Rezapour
Abstract
Abstract
Nowadays, environmental pollution by heavy metals is one of the most serious threats of the world which needs effective remediation actions. The aim of this study was to investigate the potential use of Atriplex [Atriplex verucifera], Salicornia [Salicornia europaea] and Chenopodium Album in ...
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Abstract
Nowadays, environmental pollution by heavy metals is one of the most serious threats of the world which needs effective remediation actions. The aim of this study was to investigate the potential use of Atriplex [Atriplex verucifera], Salicornia [Salicornia europaea] and Chenopodium Album in simultaneous uptake and accumulation of Na and Cd or Pb in two calcareous soils with different properties. Two soils, including a saline-sodic-calcareous (S1) and a calcareous (S2) soil, were selected. Different concentrations of Pb (0, 250, 500 and 1000 mg Pb kg-1 soil) and Cd (0, 10, 30 and 100 mg Cd kg-1) were then added to the soils. . The contaminated soils were incubated under a wetting-drying moisture regime for nearly seven months. The plants seeds were grown in pots containing different treatments of polluted soils and in control treatment (no Cd and Pb contaminations). The plant yields and concentrations of Pb, Cd and Na in the soil and plant samples were measured. Results showed that relative yield of Salicornia was more in soil S1, whereas those of Atriplex and Chenopodium Album were more in soil S2. In saline- sodic soil, the values of Na bioconcentration factor (BCENa) in control treatment were 67, 202 and 57 for Atriplex, Salicornia and chenopodium album respectively. The high value of BCENa in Salicornia revealed the ability of this plant in absorption and accumulation of Na from soil. A considerable accumulation of soil Cd by Salicornia and Pb accumulation by Atriplex and Salicornia was observed under unsuitable conditions of the saline-sodic soil, whereas, Atriplex and Chenopodium had high capability for Cd in the soil S2. These results revealed that these plants could be used for remediation of Pb and Cd contaminated soils. In this study, Salicornia with lower rate of yield reduction had the highest tolerance to Cd-stress and it seems that one can use this plant for phytiremediation of Cd and Pb from saline- sodic soil even in high concentrations of Cd and Pb.
Keywords: Bioaccumulation, Sodium (Na), Lead (Pb), Cadmium (Cd), Halophyte plants
