شبيه سازي حركت كادميم، مس، سرب و روي در يك خاك دست نخورده آهكي تحت كشت گندم و گلرنگ با استفاده از مدل انتقال املاح HYDRUS-1D

Simulation of Cd, Cu, Pb and Zn Movement in an Undisturbed Calcareous Soil under Wheat and Safflower using HYDRUS-1D Model

Anthropogenic release of heavy metals (HMs) has resulted in a continuous buildup of HMs in agricultural soils. Uptake of HMs by crop plants may lead to through food chain transfer to humans, and on the other hand, leaching of HMs through deep seepage may cause groundwater contamination. The objectives in this study were to assess the applicability of HYDRUS-1D code for simulating the mobility of Cd, Cu Pb and Zn under two common crop plants with different rooting systems (wheat (Triticum aestivum) with fibrous roots, and safflower (Carthamus tinctorious) with taproot) in the arid area soils of Isfahan. Iran. The study was conducted with undisturbed soil columns (Typic Haplocafcids) taken from a wheat and a safflower field located in the same unit of soil type. The top 10 cm of the columns was artificially contaminated with Cd, Cu, Pb, and Zn at concentrations of 15, 585, 117 and • 094 mg kg*1, respectively. A half of the columns were planted with wheat and the other with safflower according to the forms cultivation precedence. Leachate was collected continuously. Following harvest of the crops, soil samples were collected at 10-cm depth intervals and analyzed for water-extractabie metals. HYDRUS-1D code was employed to model metal transport in the soil columns as well as the metal uptake by plants. Model parameters were estimated through inverse modeling while using the SUFI-2 procedure. The results indicated that safflower resulted in larger metal concentrations at deeper depths than wheat. Metal concentrations were higher in drainage discharge of safflower columns as compared to those of the wheat columns. The simulation results obtained through HYDRUS-1D were acceptable except that adsorption constants were much lower than in the laboratory measured ones. This indicates that in HYDRUS-1D, the adsorption parameters were underestimated to allow for a deeper transport of metals, which had actually occurred due to in macropore flow in undisturbed soil. The results showed that HYDRUS-1D could well predict Cd, Cu and Pb uptake by wheat and Cd uptake by safflower. However, on overestimation of metal uptake by plants occurred when HYDRUS model simulation employed