Application of Hydrus -1D Model to Simulate the Transport of some Selected Heavy Metals in Paddy Soil in Thanh Tri, Hanoi
Main Article Content
Abstract
Abstract: Application of fertilizers and pesticides or using waste water for irrigation can result in an accumulation of heavy metals (HM) in cultivation areas. Under flooding condition of the paddy soils, HM can be leached and result in a potential risk for groundwater. In this study, Hydrus – 1D was applied to simulate the infiltration of Cu, Pb and Zn in paddy soils (in Huu Hoa, Dai Ang and Ta Thanh Oai communes, Thanh Tri district, Hanoi) in the time span from 1 to 720 days. Simulations were based on input data of the soils: texture, bulk density, Freundlich constants (Kf and β), head pressure as 20 cm ± 10 cm and assummed concentrations of the HM in irrigated water as 0.5 mmol Cu cm-3, 0.1 mmol Pb cm-3 and 0.75 mmol Zn cm-3.
Leaching rates of the HM were observed to decrease in the order: Zn > Cu > Pb. Under constant flooded conditions at a water table of 20 cm, Cu, Pb and Zn were estimated to reach 1 m deep in the soil domain within 193, 312 and 450 days, respectively. At water layers of 10 and 30 cm, the leaching rate of HM increase or decrease 17%, respectively. Speciation experiments revealed that Zn transport might be affected by the presence of Fe-, Al-oxides, while the factor prohibiting the leaching rate of Cu was soil organic matter. Pb showed a strong dependence on both Fe-, Al-oxides and organic matter. These results reinforce the necessity of using transport models to improve predictions of HM transport and more efficient remediation of contaminated aquifers. Uncertainties in modeling arise as several parameters in the simulation can be determined only with significant errors. However, Hydrus-1D is a suitable tool for simulation of the transport of HM in paddy soil.
Keywords: Hydrus-1D, simulation, transport, heavy metal, paddy soil.References
[2] Nguyen, M.K., Pham, Q.H., Ingrid Öborn, 2007. Nutrient flows in small-scale peri-urban vegetable farming systems in Southeast Asia A case study in Hanoi. Agriculture, Ecosystems and Environment, 122, 192-200.
[3] Nguyen,. M.K, Pham,Q.H, Ingrid Öborn, 2006. Element balance as a tool to assess the potential risk contamination for soil environment – A case study of heavy metal balance in peri-urban agriculture of Hanoi city. Vietnam Soil Science, 26, 112-118 (in Vietnamese)
[4] Infantino A., Pereira T., Ferrari C., Cerejeira M.J., Guardo A.D., 2008. Calibration and validation of a dynamic water model in agricultural scenarios. Chemosphere 70, 1298-1308.
[5] Christen E.W., Chung S.O., Quayle W., 2006. Simulating the fate of molinate in rice paddies using the RiceWQ model. Agri. Water Manage. 85, 38-46.
[6] Inao K., Kitamura Y., 1999. Pesticide paddy field model (Paddy) for predicting pesticide concentrations in water and soil in paddy fields. Pest. Sci. 55, 36-42.
[7] Šimůnek, J., Sejna, M., van Genuchten, M.Th., 1998. The HYDRUS-1D software package for simulating the one-dimensional movement of water, heat, and multiple solutes in variably-saturated media. Version 2.0, IGWMC-TPS-70, International Ground Wate rModeling Center, Colorado School of Mines, Golden.
[8] Nguyen N.M., Dultz S., Kasbohm J. (2009). “Simulation of retention and transport of copper, lead and zinc in a paddy soil of the Red River Delta, Vietnam”, Agriculture, Ecosystems and Environment ,129, pp 8–16.
[9] Wan Zuhairi, W.Y. 2003a. Sorption capacity on lead, copper and zinc by clay soils from South Wales, United Kingdom. Journal of Environmental Geology, 45(2), 236 - 242.
[10] Wan Zuhairi, W.Y. 2003b. Heavy Metal Sorption Capabilities of some Soil Samples from Active Landfill Sites in Selangor. Geological Society of Malaysia Bulletin, 46, 295-297.
[11] Wan Zuhairi W.Y. 2004. Natural sorption capability of heavy metals: Granitic residual soil from Broga and marine clay from Sg. Besar Selangor. Geological Society of Malaysia Bulletin, 48, 13-16.
[12] Le, D., Pham, V.K., Le, B.V.B., Duong, T.O., 2000. Preliminary study on adsorption capacity and diffusion rate of heavy metals in Red River alluvial soil at Trung Van commune, Tu Liem district, Hanoi. In: Proceedings of the Second Scientific Conference, University of Science on Environmental Science. Vietnam National University Publishing House-2000, p. 152. (in Vietnamese)
[13] Wang, C.X., Mo, Z., Wang, H., Wang, Z.J., Cao, Z.H., 2003. The transportation, time-dependent distribution of heavy metals in paddy crops. Chemosphere 50, 717–723.