Biological and Environmental Sciences Department, College of Arts and Sciences, Qatar University, Qatar
The increasing need for water in the arid areas of the world has resulted in the emergence of wastewater application for agriculture and landscape. Using treated wastewater in agricultural irrigation can provide more adequate supply of high quality water for human consumption, but their heavy metal applications effect must be regulated to ensure no physiological problems for both the plant and its consumer. The objective of the present research was to study the effects of treated wastewater on soil chemical properties and plant growth characteristics as well as accumulation of heavy metals in plant tissues. This research was conducted at Qatar university greenhouse in the growing season of 2007. Treated wastewater was obtained from Abu Nakhala pond in Doha City, Qatar. The soil was a mixture of sand and clay with ratio of (1:1). Two crop plants were used in this study; grain sorghum (Sorghum bicolor L.) and Sunflower (Helianthus annuus L). Plants were irrigated with four different mixtures of wastewater and sea water (1:0, 1:1, 3:1, and 0:1) in addition to potable water as a control. The accumulation of salts and heavy metals in the soil as well as concentration of the nutrients and heavy metal accumulation in the plant tissues were determined at the end of the experiment. Cr, Mn and Zn showed significant differences between soil irrigated with portable tap water and other irrigation treatments. On the other hand, Al, Fe, Ni, Co, Cu, As, Cd and Pb did not show significant differences among the irrigation water treatments. Sorghum soils have significantly less concentration of Co, Cu and As compared to that of Sunflower soils. Sorghum was found to accumulate significantly higher concentration of Mn and Zn (72.47 and 92.00 mg/L, respectively) than that of Sunflower. On the other hand, Sunflower has significantly higher concentration of Cr compared to that of Sorghum.