Environmental Risk Assessment and modeling Heavy Metals Uptake by Barely irrigated with water containing heavy metals
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Date
2017-04-19
Authors
نصار, دعاء ماجد عبد الرحيم
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Publisher
An-Najah National University
Abstract
This experiment was implemented in order to study the effect of the irrigation of simulated treated wastewater on soil, shoots and roots of barely and to mitigate the risk resulting from this irrigation, if any. The experiment was conducted under controlled conditions in the greenhouse at the Faculty of Agriculture and Veterinary Medicine, An-Najah National University, Tulkarm (Khadouri) during growing season (2013/2014). The barely was cultivated in plastic pots (6x6x7 cm) filled with agricultural sand in three blocks. The plants were irrigated using tap water, water simulated to the effluent of water treatment plant, water simulated to the effluent of water treatment plant after 3 years, after 9 years and after 15 years with three replicates for each treatment. Height of the shoot and number of leaves were monitored during the season. Chemical analysis was used for determining the heavy metals content (Cd, Cu, Cr, Fe, K, Mn, Ni, Pb, Zn) in each part of the plant (soil, shoots and roots) using the ICP-MS and these tests was conducted at An Najah National University (Water and Environmental studies institution laboratories). The collected data were analyzed using one way analysis of variance. Means were separated using the Duncan’s multiple range test with P ≤ .05, and the linear regression analysis. Risk assessment was performed using AS/NZS ISO 31000: 2009 Risk Management – Principles and Guidelines. Enrichment factor, bio concentration factor and translocation factor were calculated. Results showed that the water type had no effect on the plant height in all treatments, whereas it affected the number of leaves, they decreased with time. Barely irrigated with the simulated treated wastewater showed a significant difference except for Zn. Cd, Cu, K and Mn have the highest concentration in plants, on the other hand, the remaining metals have higher content absorbed by soil. When comparing metal content in shoots, roots and soil with world health organization (WHO) thresholds in each, Cd, Fe, Pb and Zn were higher than the permitted levels in shoots, also Cd, Fe and Pb were higher than the permitted levels in roots. Whereas all the metals had lower content than the permitted levels of WHO in soil. When using the linear regression analysis, the p- value was > 0.05 in all models except for Chromium in plant. Enrichment factor, bio concentration factor and translocation factor have been calculated. From that, almost the values were > 1 indicating that the larger contents of heavy metals were in the plant.
In conclusion, the crop and soil quality parameters were significantly affected by long term irrigation with the treated wastewater, and this continuous treatment may lead to accumulation beyond the thresholds set by WHO. It should be noted that these results were observed using the simulated treated waste water over the years without taking into consideration the leachate property.
In addition the barely can be used for the phaytoextraction process for some metals (Cd, Cu, K, Mn and Zn). The treated waste water could not be used as an alternative to the fresh water for irrigating the barely.