Maio 2014 vol. 1 num. 1 - 10th World Congress on Computational Mechanics
Full Article - Open Access.
MODELING VADOSE ZONE CONTAMINANT TRANSPORT AND ROOT SOLUTE UPTAKE IN A PHYTO-EXTRACTION PROCESSES
Phyto-extraction is an in situ remediation technique involving the uptake of contaminants by plant roots and their subsequent accumulation in plant tissues. It stands out for its simplicity and low costs but nevertheless it is not widely used because of difficulties in estimating its efficiency and the required remediation time. Results depend on a complex set of interactive soil, plant, contaminant and atmospheric processes and parameters. Thus, the objective of this research was to numerically estimate the effectiveness of phytoextraction, varying some project parameters. Remediation of Cd2+, Pb2+ and Zn2+ contaminants by Chrysopogon zizanioides (Vetiver grass) was simulated using the Hydrus-1D software package. Variably-saturated flow was described using the standard Richards’ equation, and solute transport using the advection-dispersion equation. Sink terms in the governing flow and transport equations accounted for root water and solute uptake, respectively. Sorption of metals by the solid phase was described using linear isotherms. Two models for contaminant uptake by the roots were used: passive uptake in which uptake is proportional to the solution concentration, and active uptake as described with a Michaelis-Menten kinetic equation. All the applied models were adjusted on greenhouse remediation experiments in previous study. Dynamic field conditions (data from the coastal lowlands of the municipality of Rio de Janeiro) were considered. Several scenarios were tested, including different planting densities and irrigation schemes. The sensitivity analysis permitted to identify several trends in the simulations. It was found that the efficiency of phyto-extraction decreased significantly when contaminant sorption increased (higher retardation factors). By comparison, phyto-extraction was more efficient in time for more mobile contaminants, depending upon the advective contaminant transport velocity in the root zone, the potential transpiration rate, and prevailing water stress conditions in the soil root zone. While more elaborate calibrations may be needed using long-term field data, this study provided useful insight into the phyto-extraction process important for the design of future experiments.
Palavras-chave: Non-saturated soil, Richard equation, contaminant transport, plant solute uptake,
-  ITRC, "Phytotechnology Technical and Regulatory Guidance and Decision Trees, Revised, PHYTO-3". Interstate Technology Andamp; Regulatory Council, Phytotechnologies Team, Tech Reg Update, Washington, D.C., 2009.
-  Truong P.N.V., Foong Y., Guthrie M., Hung Y.-T., "Phytoremediation of Heavy Metal Contaminated Soils and Water Using Vetiver Grass". in Environmental Bioengineering, Wang L.K., et al., Eds., Humana Press, 233-275, 2010.
-  Šimunek J., Šejna M., Saito H., Sakai M., van Genuchten M.T., "The HYDRUS-1D Package for Simulating the Movement of Water, Heat, and Multiple Solutes in Variably Saturated Media, Version 4.08". Department of Environmental Sciences, University of California, Riverside, California, USA, 2009.
-  Lugli F., van Genuchten M.T., Mahler C.F., "Phytoremediation: Simultaneous calibration of contaminant soil sorption and plant uptake". in SETAC Europe 21st Annual Meeting, Milan, 2011.
-  Feddes R.A., Zaradny H.K., Kowalik P.J., "Simulation of Field Water Use and Crop Yield". New York, NY, USA, John Wiley Andamp; Sons Inc, 1978.
-  Vogel T., "SWMII-Numerical model of two-dimensional flow in a variably saturated porous medium". Research report nr. 87. Vakgroep Hydraulica en Afvoerhydrologie. LUW (1988) 120 pp., 1988.
-  Jungk A.O., "Dynamics of nutrient movement at the soil-root interface". in Plant roots: The Hidden Half, Waisel Y., Eshel A., and Kafkafi U., Eds., Marcel Dekker, Inc. New York, 587-616, 2002.
-  Šimunek J., Hopmans J.W., "Modeling compensated root water and nutrient uptake". Ecological Modelling, 220(4), 505-521, 2009.
-  van Genuchten M.T., "A Closed-Form Equation for Predicting the Hydraulic Conductivity of Unsaturated Soils". Soil Science Society of America Journal, 44(5), 892-898, 1980.
-  Tomasella J., Pachepsky Y., Crestana S., Rawls W.J., "Comparison of two techniques to develop pedotransfer functions for water retention". Soil Science Society of America Journal, 67(4), 1085-1092, 2003.
-  Allen R.G., Jensen M.E., Wright J.L., Burman R.D., "Operational estimates of reference evapotranspiration". Madison, WI, USA, American Society of Agronomy, 1989.
-  Allen R.G., Pereira L.S., Raes D., Smith M., "Crop evapotranspiration: guidelines for computing crop water requirements". FAO Irrigation and Drainage Papers, Rome, Italy, Food and Agriculture Organization of the United Nations, 1998.
-  Soares M.R., "Distribution Coefficient (Kd) Of Heavy Metals In Soils Of The State Of São Paulo". PhD Thesis, Agronomy Department, Agriculture School "Luiz de Queiroz" / USP, Piracicaba, São Paulo, 2004.
-  Shackelford C.D., Daniel D.E., "Diffusion in Saturated Soil .1. Background". Journal of Geotechnical Engineering-ASCE, 117(3), 467-484, 1991.
-  Tavares S.R.d.L., "Phytoremediation of Soil and Water in Areas Contaminated by Heavy Metals from the Provision of Hazardous Waste". PhD Thesis, Civil Engineering Department, COPPE / Federal University of Rio de Janeiro, Rio de Janeiro, 2009.
-  Wesseling J.G., "Meerjarige simulatie van grondwaterstroming voor verschillende bodemprofielen, grondwatertrappen en gewassen met het model SWATRE". Wageningen, DLO-Staring Centrum, 1991.
-  Lugli F., "Numerical Modeling of Phytoremediation Processes of Soils". M.Sc. Thesis, Civil Engineering Department, COPPE / Federal University of Rio de Janeiro, Rio de Janeiro, 2011.
-  CONAMA, "Resolução no 420". Publicação DOU nº 249, do 30/12/2009, 81-84, 2009.
Lugli, F.; Mahler, C. F.; "MODELING VADOSE ZONE CONTAMINANT TRANSPORT AND ROOT SOLUTE UPTAKE IN A PHYTO-EXTRACTION PROCESSES", p. 4924-4932 . In: In Proceedings of the 10th World Congress on Computational Mechanics [= Blucher Mechanical Engineering Proceedings, v. 1, n. 1].
São Paulo: Blucher,
ISSN 2358-0828, DOI 10.5151/meceng-wccm2012-20146
últimos 30 dias | último ano | desde a publicação