Evaluation of Spatial and Temporal Variation of Heavy Metals in Soil, Water and Rice Grain (Case Study: Khoramabad Plain, Iran)

In order to study the spatial and temporal variation of heavy elements in soils, water and rice, a research project was done in Khoramabad area and repeated with three months of May, July and September respectively. Per each test site 5 samples were selected, finally soil samples were collected. The amount of lead, nickel and cadmium was analyses. For both nickel, lead and cadmium change is not significant when the time period studied. Two-way analysis of variance test results show the spatial variation of nickel, cadmium and lead levels are a significant percentage. For both nickel and lead and cadmium change is not significant when the time period studied, significant changes in expression levels of these elements in soils was studied. The amount of Cd in paddy fields averaged 0.182 micrograms per gram of soil, which is equivalent to 663 grams per hectare. In comparison to German and Swiss standards (with respectively 33 and 75 g Cd per hectare) it is very high. The amount of Cd in grains of rice on average 0.115 micrograms per gram of dry matter is due to the amount of harmful cadmium in plants for human 0.1 microgram reported currently moderate in the tissues of rice above the limit and it is harmful for human consumption.