M. Biria; Abdulamir Moezzi; H. AmeriKhah
Abstract
Introduction: Among wide variety of soil pollutants including heavy metals, acidic precipitation and other toxicants, the importance of heavy metals due to their pollution capacity has received growing attention in recent years. These metals enters into soil through municipal and industrial sewage as ...
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Introduction: Among wide variety of soil pollutants including heavy metals, acidic precipitation and other toxicants, the importance of heavy metals due to their pollution capacity has received growing attention in recent years. These metals enters into soil through municipal and industrial sewage as well as direct application of fertilizer and pesticides. High cadmium and lead concentration in soil lead to severe environmental pollution. Such pollution not only has a destructive effect on crop yield but also endangers human being and other creatures’ health after entering in their food chain. Several physical, chemical and biological methods used to reduce the adverse effect of high concentration of heavy metals in soil. In spite of the hight cost, these methods are not always suitable for reclamation of small area and mostly have side effect on physico-chemical and biological characters of soil, after application. Biochar produced by thermal decomposition of biomass in the absence or presence of low oxygen. These material due to their high spacific surface area and high cation exchange capacity may have great ability to absorb charged material including heavy metals. Therefore in this study attempt is made to evaluate the effect of sugarcane bagasse –derived biochar in improving maize plant growth in cadmium and lead contaminated soils.
Material and methods: This study was carried out during the year 2014 in two separate experiments in Shahid Chamran university. The treatments in each case consisted of two levels of sugarcane bagasse made biochar (0 and 4 percent by weight) in combination with each soil, properly contaminated with 50 and 100 mg cadmium per kg soil in first experiment and 500 and 1000 mg lead per kg soil in the second. The treated soils were applied to pot and arranged in a complete randomized block designe and replicated 3 times. Prior to introduction of soil to pots, the heavy metal contaminated soils with moisture content around 70 percent of F.C. were incubated for 30 days. During incubation period sugarcane bagasse was dried, milled, sieved, compacted and subjected to traditional furnace at 550 oc for 3 hours on low pyrolysis. The furnace temperature was controlled manually using lesser thermometer. The furnace cooled down and the collected sugarcane bagasse made biochar sieved again. The incubated soil mixed with proper amount of sugarcane bagasse made biochar and incubated under previous condition for 45 days. The treated soils were poured to the labeled pots and 3 maize seeds were sown in each pot and two weeks after emergence thinned to one plant per pot. Nineteen days after sowing, the height of the plants and chlorophyll index were recorded and plants were harvested and leaf area of each plant was recorded, maize root content of each pot were carefully separated from soil and along with shoot property washed, dried, weighed and after milling subjected to chemical analysis. Prior to sowing maize seeds some of physic- chemical properties of untreated soil were estimated. Furthermore few charactoristics of sugarcane bagasse made biochar including pH and EC in 1 : 10 solution of biochar to water recorded. N, C, H, O concentration were estimated by elementary analyzer. Cation exchange capacity of sugarcane bagasse made biochar was measured by ammonium acetate method. Moreover its functional group determined by FT-IR method. Specific surface area estimated as per Branuar Emmet Teller (BET) method. Sugarcane bagasse made biochar image was obtained from scanning electron microscope. Cadmium and lead concentration in root and shoots were estimated by atomic absorption spectrometer after wet digestion. SAS software was used for statistical analysis data which fallowed by Duncan test to compare the mean values.
Results and discussion: The results showed that implementation of cadmium and lead led to decrease in chlorophyll index, leaf area, height of plant and root and shoot dry weight significantly. But the sharp decline in the concentration of cadmium and lead in root and shoot after sugarcane bagasse made biochar application improved chlorophyll index, leaf area, height of plant, root and shoot dry weight. Application of 4% Sugarcane bagasse made biochar, decreased transfer factor (TF) and bioaccumulation factor (BF) of these elements compared to control. The results showed high capability of sugarcane bagasse made biochar to absorb cadmuim and lead and reduce their availability to plant respectively. In fact application of sugarcane bagasse made biochar dwindled cadmium and lead absorption as well as their transfer factor and bioaccumulation factor, and hence improved plant growth.
Conclusion: The results obtained after sugarcane bagasse made biochar application mainly initiated due to high cation exchange capacity of which eventually was created by large number of functional groups in its high specific surface area (table 2) to stabilize cadmium and lead and render them unavailable to plant and hence improve its growth.
Hemmatollah Pirdashti
Abstract
Soil pollution by heavy metals due to industrial activities, factories, fertilizers and pesticides is an environmental problem which threatens public health. Therefore, it is necessary to find some solutions to ameliorate the negative effects of heavy metals in soil. Accordingly, an experiment was designed ...
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Soil pollution by heavy metals due to industrial activities, factories, fertilizers and pesticides is an environmental problem which threatens public health. Therefore, it is necessary to find some solutions to ameliorate the negative effects of heavy metals in soil. Accordingly, an experiment was designed to evaluate the effect of Trichoderma harzianum fungi as a cadmium (Cd) biosorbent in barley (cv. Sahra) cultivated on a Cd contaminated soil. Treatments were arranged in factorial experiment based a completely randomized design and were replicated three times. Experimental factors consisted of T. harzianum fungi at two levels (inoculated and non-inoculated control) and four levels of cadmium nitrate (0, 50, 100 and 150 mg L-1). Results indicated that Trichoderma inoculation increased barley biological yield (by 36%) as compared to those in non-inoculated plants. Where Cd was added, both Cd amount in soil and Cd bioaccumulation in plants markedly increased. The Cd content in barley root varied from 0.02 mg kg-1 in non-contaminated soil to 688.2 mg kg-1 in 150 mg L-1 contaminated soil. Furthermore, the presence of the Trichoderma significantly increased the Cd uptake in plant roots (from 53 to 96%) in moderate to high levels of cadmium contamination when compared to those in non-inoculated plants. The maximum Cd phytoextraction (5.260 mg per pot) resulted in Trichoderma inoculated plants and at maximum rate of Cd which was 100% greater than untreated plants. In conclusion, it seems that inoculation of Trichoderma with barley plants could be an optimum option to remediate the Cd contaminated soils.
jalil kakeh; manoochehr gorji
Abstract
Biological soil crusts (BSCs( result from an intimate association between soil particles and cyanobacteria, algae, fungi, lichens and mosses in different proportions, which live on the surface, or immediately in the uppermost millimeters of soil. Biological soil crusts, are important from the ecological ...
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Biological soil crusts (BSCs( result from an intimate association between soil particles and cyanobacteria, algae, fungi, lichens and mosses in different proportions, which live on the surface, or immediately in the uppermost millimeters of soil. Biological soil crusts, are important from the ecological view point and their effects on the environment, especially in rangeland, and desert ecosystems. These effects have encouraged researchers to have a special attention to this components of the ecosystems. The present study carried out in Qara Qir rangeland of Golestan province, Iran, to investigate the effects of BSCs on Soil saline-sodic properties. In the study area, four sites were selected which included sections with and without BSCs. Soil sampling was carried out in each section for depths of 0-5 and 5-15 cm, with four replication. The gathered data from soil samples were analyzed by nested plot. Results showed that BSCs than non-BSCs, significantly decrease the amount of soil acidity, calcium carbonate and soil saline-sodic properties such as electrical conductivity, sodium, calcium and magnesium concentration, sodium adsorption ratio, and exchangeable sodium percentage at both depths. In general, it can be concluded that BSCs enhance soil infiltration rate and available water content, that together their bioaccumulation properties, leads to decreasing soil saline-sodic properties. Potassium concentration did not differ among areas covered by BSCs and without BSCs. But infiltration rate and available water content were increased significantly in two mentioned depths on sites covered with BSCs than without BSCs. In general, it can be concluded that BSCs enhance soil infiltration rate and available water content, that together their bioaccumulation properties, leads to decreasing soil saline-sodic properties.
