Gh. Rahimi; F. Karimi
Abstract
Introduction: Salinization of soil has been reported as a problem in many parts of the world. Salinization could occur either as a result of natural processes e.g. high concentrations of salt in parent materials or groundwater and/or anthropogenic actions such as over-irrigation. The salinization probably ...
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Introduction: Salinization of soil has been reported as a problem in many parts of the world. Salinization could occur either as a result of natural processes e.g. high concentrations of salt in parent materials or groundwater and/or anthropogenic actions such as over-irrigation. The salinization probably affects the chemical and physical properties of soil, soil microbiological processes, plant growth, and soil fauna. Both quantity and quality of water, however, are the most important eco-factors needed for earthworm survival and development, and also biodegradation processes. Materials and Methods: In order to investigate the effect of irrigation water salinity on the survival and growth of earthworm Eisenia Fetida, an experiment was conducted in a completely randomized design with three replications under environmental conditions of the laboratory of Soil Sciences Department of Bu-Ali Sina University in Hamedan. The different types of water used in this study were: distilled water and saline water made with NaCl salt with electrical conductivity (EC) of 2, 4, 6, and 8 dS m-1. The experiment was carried out using completely randomized design in plastic containers of size 19 × 13 × 8 cm. Ten earthworms per container used in each exposure regime were introduced into the relevant test salinity by placing them on the surface and allowing them to burrow in. The test containers were covered with perforated lids to limit water loss due to evaporation and kept in 16 hours light, 8 hours dark at 25°C in a climate chamber for 42 days. Sampling was done at 3, 15, 21, 27, 33, 39, and 42 days after earthworms were introduced to the substrates to investigate mortality and weight changes of earthworms. The LC50 (concentration at which 50% of the earthworms are killed) and the EC50 (effect concentration at which a 50% reduction in a measured parameter) values for the salts expressed as conductivity (dS m-1) were calculated on day 27 and 42 by using the Probit Analysis. Results and Discussion: On day 3, no significant effect of salinity on percentages of survival was found. The survival rate of Eisenia fetida was significantly affected in the EC range used during 42 days (Table 2). The irrigation with distilled water (EC0) had the highest survival rate while the irrigation water with EC 8 dS m-1 had the lowest value. During the 39 days of exposure, no significant difference was found in survival rate of earthworms between EC 2, EC 4 and EC 6 dS m-1, but at the end of day 42, the salinity levels with EC 8 dS m-1 had a significant effect on percentage of earthworm survival in which 91.68% mortality occurred. The mean weight change of earthworms exposed to water with EC 2 dS m-1 was not significantly different (p < /em> < 0.01) from those exposed to the distilled water during 39 days, but there was a decrease in earthworm weight on day 42. The calculated LC50 for mortality after 27 and 42 days was 7.5 and 4.31 dS m-1, respectively, and EC50 for growth was 7.94 and 6.82 dS m-1, respectively. Conclusion: Our results showed that increased salinity had harmful effects on the growth and mortality of the earthworms (Eisenia fetida). Salinity can have detrimental effects on earthworms at concentrations considered safe for many plant species. We determined 42 day LC50 for mortality 4.31 dS m-1 (2521 mg lit-1). The EC50 for growth was 6.82 dS dS m-1 (3989 mg lit-1). The weight of earthworms was significantly affected by NaCl and dispersion analysis showed that NaCl concentration had a statistically significant influence on the weight of earthworms. The argument for using NaCl is that it is the predominant salt in most saline environments particularly in wastewaters. Since the salt type is dependent on the source of the contamination, it is, therefore, possible that other salts apart from NaCl could be the main compounds in saline toxicity in a specific area. The results of the current study suggest that the effects of salinity depend on the salt composition. Therefore, it would be important to assess the type of salt ions in soil in risk assessment, as this affects the extent of toxicity to soil organisms.
M. Shakarami; S. Marofi; Gh. Rahimi
Abstract
Introduction: Arid and semi-arid areas are confronting increasing water shortages. In these regions of the world, planners are being forced to consider other water sources that could be used economically and effectively to promote further development. Wastewater is the only potential water source, which ...
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Introduction: Arid and semi-arid areas are confronting increasing water shortages. In these regions of the world, planners are being forced to consider other water sources that could be used economically and effectively to promote further development. Wastewater is the only potential water source, which will increase as the population grows and the demand on freshwater increases. Composting municipal solid wastes (MSW) and sewage sludge is a good way to reduce the amount of wastes generated in densely populated areas. Municipal solid waste production in Asia in 1998 was 0.76 million tons per day, with an annual growth rate of 2- 3% in developing countries and 3.2- 4.5% in developed countries. (MSW) compost is increasingly used in agriculture not only as a soil conditioner but also as a fertilizer. Despite the growing interest in wastewater and compost usage, excessive application of them may have some harmful effects such as human health problems, runoff and leaching of nutrients to surface and groundwater, undesirable chemical constituents, pathogens, accumulations of heavy metals in plants and soils, negative environmental and health impacts. So, using of wastewater and compost application should be under controlled conditions that minimize health risks of agricultural products.
Materials and Methods: This study was conducted in greenhouse of Bu-Ali Sina as a factorial completely randomized design to evaluate the effects of wastewater and compost on physical and chemical properties of soil. The factors included four types of watering: raw wastewater (W1), treated wastewater (W2) combined 50% of raw wastewater and fresh water (W3) and tap water (W4) and also four compost levels: 0 (C1), 40 (C2), 80 (C3) and 120 tha-1 (C4). Therefore, 16 treatments (W1C1 to W4C4) were considered for investigation. It is noted that Compost added and mixed just with top layer of the soil. 48 volumetric lysimeters were applied as Cultivation beds (26 × 30 × 30 cm). The soil had three layers: the upper layer (Clay texture), the middle layer (clay loam) and the bottom layer (sandy clay loam). After beds preparation, basil (Ocimum Basilicum) was planted in them. Due to the lack of an active wastewater treatment plant in the region, raw and treated wastewaters were transported from Kermanshah, the nearest city to Hamedan. Also, municipal compost was prepared from Kermanshah Compost Company.At the end of cultivation period, the soil samples (from 0-15 cm) were collected and the amount of physical (hydraulic conductivity, bulk and particle density and porosity)and chemical (nitrogen, phosphorus and potassium) properties were measured.
Results and Discussion: The results showed that the water quality has a significant effect on all parameters and the amount of compost has significant effect on all parameters except bulk density. But, the amount of all parameters (except hydraulic conductivity) was not influenced by interaction between water quality and compost levels. In all treatments, the range of hydraulic conductivity, bulk density, particle density and total porosity were varied between 23.82 to 35.61 mmh-1, 1.41 to 1.43 grcm-3, 2.51 to 2.57 grcm-3 and 42.88 to 45.19 %, respectively. Also the range of nitrogen, phosphorus, and potassium were varied between 0.06 to0.08 %, 14.64 to232.28mgkg-1,and 393.22 to519.84mgkg-1,respectively.Overall, the results indicated that using compost and wastewater increased hydraulic conductivity, porosity, nitrogen, phosphorus, and potassium of the soil in comparison to the control. Whereasbulk and particle density of soil decresed by using compost and wastewater (as a mixed material).
Conclusion: In this study, we investigated the effect of wastewater and compost on some of soil physical properties (hydraulic conductivity, bulk density, particle density and total porosity) and also some of chemical properties of soil nitrogen, phosphorus and potassium).The results showed that the use of wastewater and compost on soil physical condition has a positive effect.Wastewater and compost by improving the soil pore size distribution, decreased the bulk and particle density and increased porosity and hydraulic conductivity of the soil. The impact of wastewater and compost to improve the physical properties, commensurate with the level of wastewater treatment and composting rate in the soil. Also using the wastewater (raw wastewater, treated wastewater and combined 50% of raw wastewater and fresh water) and compost (40, 80 and 120 tha-1), compared to the control (fresh water and soil without compost), increased total of nitrogen, phosphorus and potassium of soil. But, due to the risks of soil salinity and nitrogen leaching, it is suggested that longterm exposure to wastewater and compost needs a careful practical management.
Ghasem Rahimi
Abstract
In order to assess uptake potential of Cd an Zn by Gladiola, Narcissus and Tulip, the greenhouse study was performed in contamination soils as factorial arrangement based on the complete randomized design with different levels of pollution (A as higher pollutant, B as lower pollutant and C as no pollutant) ...
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In order to assess uptake potential of Cd an Zn by Gladiola, Narcissus and Tulip, the greenhouse study was performed in contamination soils as factorial arrangement based on the complete randomized design with different levels of pollution (A as higher pollutant, B as lower pollutant and C as no pollutant) and different flowers (Gladiola, Narcissus and Tulip) with four replicates in faculty of agriculture, Bu-Ali Sina University. The result showed that with increasing heavy metals concentration in soils, dry matters of Gladiola and Tulip were decreased, compared with the control; however there was no change for dry matter in Narcissus. The accumulation of Cd and Zn by flowers increased with increasing soil pollution. The Cd concentration was higher (3.48 mg/kg averagely) in aerial parts of plant harvested from the A level treated soils which was significantly difference with B and C levels treated soil. There was no difference between the B and C level treated significantly. The Zn concentration in the aerial parts of plant was in the order of A, B and C level treated soils (in average 26.03, 17.46 and 13.99 mg/kg respectively). The Cd uptake was equal in all parts of Gladiola, Narcissus and Tulip. The Zn concentration was higher in the aerial parts of Tulip than Gladiola and Narcissus that of underground was equal. The accumulation and translocation Indices of Cd was not affected by increased soil Cd concentration significantly. With increased Zn concentration in soil, accumulation index decreased while translocation index was not changed significantly. The translocation and accumulation index of Cd and Zn was similar for flowers. Thus accumulation of Cd and Zn in saleable parts of Gladiola, Narcissus and Tulip led to clean up the contaminated soils.
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.
