Investigation of DNA changes in wheat (Triticum aestivum L.) induced by cadmium using random amplified polymorphic DNA (RAPD) analysis

In recent years, many plants have been used as bioindicators or living indices and several experiments have been conducted to evaluate the genotoxic effects of environmental pollution on plant species. Plants such as Arabidopsis and barley have been used as biological indicators by several researchers and have been able to identify DNA changes using molecular markers. This study was conducted on wheat as an important cereal that provides human daily food and has an important role in human health. The purpose of study was to evaluate the effect of different concentrations of cadmium on amounts of the soluble proteins, investigation of growth and possible changes to the structure of DNA using random amplified polymorphic DNA (RAPD) marker. In the present study, wheat seedlings were used for detection of genotoxic effects of cadmium contamination in the range of 0 to 120 mg-1. The limiting effects of cadmium on length of root and plant height and total soluble proteins in root were quite evident by increase of cadmium concentration. Change in DNA was observed using RAPD marker as there was change in number of bands, present or absent of bands at the range of above 5 mg-1 cadmium concentration. In the previous studies conducted by several researchers, variation in DNA bands was reported at levels above 30 mg-1, whereas in the present study, band variation was observed at the concentration of 5 mg-1. This study also showed that DNA stability is highly affected by cadmium pollution at >5 mg-1 which was identified by RAPD markers.Keywords: Bioindicator, cadmium, genotoxic, random amplified polymorphic DNA (RAPD) marker, Triticum aestivum LAfrican Journal of Biotechnology Vol. 12(16), pp. 1921-192

Leaching behaviour of a sandy soil amended with natural and NH4+and K+saturated clinoptilolite and chabazite

Using saturated or enriched zeolites as slow release fertilizers (SRFs) is considered as an environmental-friendly strategy to enhance use of macronutrients in sandy soils. In this paper, two natural zeolites, clinoptilolite (CLI) and chabazite (CHA) were used as mineral precursors to prepare NH4+/K+saturated clinoptilolite (NH4+/K+-CLI) and chabazite (NH4+/K+-CHA) as zeolitic nutrient sources (ZNSs). Comparison between the nutrient retention capabilities of these ZNSs was one of the main objectives of this study. The NH4+/K+-CLI and NH4+/K+-CHA were prepared by soaking the zeolites in NH4Cl and KCl solutions, respectively. Leaching tests were performed on a sandy soil amended with chemical fertilizers (CFs), NH4+/K+-CLI and NH4+/K+-CHA to evaluate the leaching properties of them. The results indicated that approximately 84% and 88% of the NH4+and K+of soils fertilized with CFs were lost during the experiment, respectively. While, the NH4+and K+losses from soils amended with NH4+/K+-CLI and NH4+/K+-CHA were 29%, 23%, and 14%, 24%, respectively. Despite of drastic changes in leaching behavior of CFs, nutrient losses from ZNSs were more uniform during the experiments. No significant difference was found between the two studied zeolites on reduction of K+loss. However, CHA was more effective in preventing NH4+loss during leaching

Heavy Metals Removal from Industrial Wastewater by Sand, Soil and Organic Matter

A greenhouse experiment was conducted with a completely randomized design with four treatments and four replicates to investigate the efficiency of sand, soil (calcareous and non-calcareous), and organic matter (rice husk and leaf compost) for the removal of copper, nickel, zinc, and chromium from industrial wastewater by filtration. PVC tubes (columns) 66.5 cm high and 10 cm diameter were chosen and each was filled from bottom to top with coarse gravel, sand, soil, organic matter, and fine gravel, respectively. Then, plating wastewater was added at nine pore volumes to each column. When the filter’s surface was completely dried, a second round of wastewater addition was performed. At the end of the experiment, the columns were cut to collect the adsorptive materials which were then air-dried and transferred to the laboratory for measurement of heavy metal concentrations by atomic absorption spectroscopy. The results showed that putting calcareous and non-calcareous soils under the applied organic matter (rice husk and leaf compost) affected their capacity for adsorbing heavy metals to varying degrees. It was also found that low the cation exchange capacity of soil compared to organic matter did not lead to its reduced adsorption capacity. Analysis of the organic matter revealed that rice husk was the best adsorbent for Cr, while leaf compost was the best for Zn and Ni. In addition, applied sand in this experiment was a good adsorbent for heavy metals in wastewater. Generally, it seems that application of the studied adsorbents was effective and that they could be recommended for the removal of heavy metals from industrial wastewater

The Study on the Effect of Cadmium, Zinc and Zeolite Application on Physiomorphological Characteristics of St. Johnʼs Wort (Hypericum perforatum L.)

Introduction: Among the heavy metals, cadmium, because of high mobility and bioavailability in soil and also toxicity at low concentrations is very important. Cadmium (Cd) is known as carcinogen and can induce many types of cancers. Human activities (metallic industries, contaminated fertilizer, herbicides or insecticides, irrigation with contaminated groundwater, and use of contaminated sewage sludge) are largely responsible for accumulation of different levels of Cd in soil. Saint John’s Wort (Hypericum perforatum L.) is a medicinal plant and belongs to the family Hypericaceae which its extract, one of the best-characterized herbal medicines, known as the Cd-hyperaccumulator, is widely sold for the treatment of depression. Hyperaccumulator plants are species able to accumulate high amounts of heavy metals in their tissue at concentrations of 10 to 100 times higher than tolerated by crop plants. Zinc (Zn) is an essential element occurring in several enzymes, where it plays a catalytic or structural role. Cadmium and zinc have similar electron configuration, valence state as well as affinity to S, N and O donor ligands and thus their geochemical and environmental properties are comparable. The antagonism activity between Cd and Zn in the environment and their chemical similarity can lead to interactions between Cd and Zn during plant uptake, transport from roots to shoots, or accumulation in edible tissues. Ion exchange is one of the methods used for the removal of several toxic substances. In recent years, natural amendments, such as zeolite have been widely used to address trace metals contamination. Therefore, adding zinc and zeolite to the growth medium of plant can be moderating the toxic effects of cadmium. Materials and Methods: This pot experiment was conducted at the Experimental Field of Ferdowsi University of Mashhad (FUM) from September 2013 to June 2014. Treatments consisted of three levels of cadmium (0, 10 and 20 mg Cd kg-1 soil), three levels of zinc (0, 25 and 50 mg Zn kg-1 soil) and three levels of Zeolite (Clinoptilolite) (0, 5 and 10g zeolite kg-1 soil) arranged in a factorial based on Randomized Complete Block Design (RCBD) with three replications. Cadmium sulfate (CdSO4·4H2O) and zinc sulfate (ZnSO4·7H2O) were purchased from MERCK company. The zeolite used in this research was collected from the Semnan mine, located in South of Semnan Province. After preparing the soil, the pots (30 cm in diameter with 18 kg capacity) were filled with 18 kg soil and thoroughly mixed with appropriate amounts of cadmium, zinc and zeolite diluted in distilled water. Seeds of H. perforatum L. cv. “Topaz” were obtained from the FUM Research Field. After 24 hours of soaking in tap water, the seeds were sown on the surface of moistened soil in each pot and germinated after 10 days. Following germination, the seedlings (about 1.0 cm high) were thinned and only 10 seedlings in each pot were kept. At the full flowering stage, these plants were harvested after 9 months. Plant height, root length, flowering stem and flower number, leaf area, relative chlorophyll and number of black nodules was measured. Chlorophyll (Chl) content were determined by leaf area meter (Li-Cor-1300,USA) and SPAD chlorophyll meter. Data were analyzed statistically by using JMP 8 and Excel software. The differences between averages were tested by Tukeyʼs test at P < 0.05. Results and Discussion: The results showed that increasing cadmium levels lead to significant decrease of 6.28, 3.45, 2.04, 5.49, 0.82, 15.71 percents in plant height, root length, flowering stem, flower number, leaf area and relative chlorophyll, respectively compared with control. In comparison to control, the number of black nodules in leaf significantly increased by 4.23 percent. Combined application of cadmium and zinc could significantly decline the effects of cadmium on plant height and root length. Meanwhile, interaction effect of cadmium and zeolite was detected significantly on root length and number of flowers. The results of three-way interactions for root length were superior in Zn0Cd0Z10 treatment. Cadmium is an inhibitor of uptake and accumulation of essential mineral nutrients, reduces conductivity of stomata andwater potential of cells and damaged photosystems; therefore, can decrease biomass production in stem, flower and root. The reduction of Chl content could lead to enzymatic degradation of these pigments or inhibition of their biosynthesis, which could be connected with Cd-induced deficiency of iron and zinc, decrease of magnesium content or cadmium bond to essential thiol groups in both the protochlorophyllide reductase protein and other enzymes involved in the light dependent synthesis of 5-aminolevulinic acid. Heavy metal stress with impact on biosynthetic pathways of pharmacologically active molecules can either increase or decrease them. Changes in black nodules number, containing hypericin and other secondary metabolites in H. perforatum in response to heavy metals can help us understand the role of this material in stress conditions. It could be assumed that high metal accumulating ability of plants producing specific secondary metabolites in H. perforatum could be also connected with chelation of toxic metals with mentioned substances. Conclusions: Our results confirmed that the addition of zeolite and zinc presumably improved plant growth, because of increased availability of essential nutrient elements such as K, Mg, Ca, NH4, and micronutrients in presence of zeolite or decreased Cd sorption and transmission in presence of zinc

Impact of monovalent cations on soil structure. Part I. Results of an Iranian soil

This study investigated the impact of monovalent cations on clay dispersion, aggregate stability, soil pore size distribution, and saturated hydraulic conductivity on agricultural soil in Iran. The soil was incubated with treatment solutions containing different concentrations (0-54.4 mmol l-1) of potassium and sodium cations. The treatment solutions included two levels of electrical conductivity (EC=3 or 6 dS m-1) and six K:Na ratios per electrical conductivity level. At both electrical conductivity levels, spontaneously dispersible clay increased with increasing K concentration, and with increasing K:Na ratio. A negative linear relationship between percentage of water-stable aggregates and spontaneously dispersible clay was observed. Clay dispersion generally reduced the mean pore size, presumably due to clogging of pores, resulting in increased water retention. At both electrical conductivity levels, hydraulic conductivity increased with increasing exchangeable potassium percentage at low exchangeable potassium percentage values, but decreased with further increases in exchangeable potassium percentage at higher exchangeable potassium percentage. This is in agreement with earlier studies, but seems in conflict with our data showing increasing spontaneously dispersible clay with increasing exchangeable potassium percentage. Our findings show that clay dispersion increased with increasing K concentration and increasing K:Na ratio, demonstrating that K can have negative impacts on soil structure

Effect of Cadmium and Lead on Quantitative and Essential Oil Traits of Peppermint (Mentha piperita L.)

Cadmium (Cd) and lead (Pb) are particularly noteworthy metals that can pollute the air, soil and water contributing to serious environmental problems. Tests were done on concentrations of Pb and Cd; treatments tested in the experiment were as follows; Cd concentrations (10, 20, 40, 60, 80, 100 ppm) and concentrations of Pb (100, 300, 600, 900, 1200, 1500 ppm) and control. Tests were done on Mentha piperita L. in a greenhouse, arranged as a randomized complete block design with three replications. Rhizomes with uniform weight were planted in pots 30�50�35 cm. Plants were irrigated with Cd and Pb chloride after germination of all rhizomes. Results demonstrated that with increasing concentrations of Cd and Pb there was a decrease in fresh and dry weights, main stem height, leaf area per plant, leaf number, number of nodes per main stem and essential oil of peppermint compared to the control. Fresh weights were decreased at 100 ppm of Cd and 1500 ppm of Pb, 18.16% and 24.55%, respectively compared to the control at the first harvest. At the second harvest, these decreases were 15.24% and 32.72%, respectively. At the highest concentrations of Cd and Pb, dry weight of peppermint was dropped 22.92% and 39.01% at the first harvest. For the second harvest, decreased dry weights were 25.88% and 26.77% respectively. It seems that peppermint can tolerate waste water or soil polluted with medium range of Cd and Pb concentrations and the essential oil percentage was not affected by these concentrations

Combined effects of polyacrylamide and nanomagnetite amendment on soil and water quality, Khorasan Razavi, Iran

Nanotechnology is increasingly being used to remediate polluted soil and water. However, few studies are available assessing the potential of nanoparticles to bind surface particles, decrease erosion, and minimize the loading of water pollutants from agricultural surface discharge. To investigate this potential, we treated in situ field plots with two practical surface application levels of anionic polyacrylamide (PAM only) with and without nanomagnetite (PAM-NM), examined soil physical properties, and evaluated the impact of this amendment on contaminant sorption and soil erosion control. Polyacrylamide and PAM-NM treatments resulted in 32.2 and 151.9 fold reductions in Mn2+, 1.8 and 2.7 fold for PO43--P, and 2.3 and 1.6 fold for NH4+-N, respectively, compared to the control. Thus, we found that the combination of PAM and NM, had an important inhibitory effect on NH4+-N and PO43--P transport from soil-pollutants which can contribute substantially to the eutrophication of surface water bodies. Additionally, since the treatment, especially at a high concentration of NM, was effective at reducing Mn2+ concentrations in the runoff water, the combination of PAM and NM may be important for mitigating potential risks associated with Mn2+ toxicity. Average sediment contents in the runoff monitored during the rainfall simulation were reduced by 3.6 and 4.2 fold for the low and high concentration PAM-NM treatments when compared to a control. This treatment was only slightly less effective than the PAM-only applications (4.9 and 5.9 fold, respectively). We report similar findings for turbidity of the runoff (2.6-3.3 fold for PAM only and 1.8-2.3 fold for PAM-NM) which was caused by the effects of both PAM and NM on the binding of surface particles corresponding to an increase in aggregate size and stability. Findings from this field-based study show that PAM-modified NM adsorbents can be used to both inhibit erosion and control contaminant transport