Non-Fickian transport of ammonia nitrogen in vadose zone: experiments and modeling
- 31 Downloads
To investigate the anomalous migration process of ammonia nitrogen in vadose zone, laboratory and numerical experiments of chloride and ammonia nitrogen are used to the transport parameters and evaluate the physical and chemical heterogeneity. Batch adsorption experiments and column experiments of silty loam and silty clay were conducted to determine key transport parameters. BTCs of chloride and ammonia nitrogen are derived using three approaches: equilibrium advection–dispersion equation (ADE), mobile–immobile model (MIM), and continuous time random walk–truncated power law (CTRW-TPL). All the models show accepted fitness to the transport process of chloride, but the CTRW-TPL fits best. For ammonia nitrogen, the CTRW-TPL with the retardation term (Λ) can fully describe the tracer-BTC, especially for late-time tailing, while the ADE and MIM cannot. Concentration fluctuation and irregular behavior in silty clay are more violent than those in silty loam. Physical heterogeneity has little effect on anomalous trait of BTCs in homogenous media. And lower permeability and mass exchange between mobile and immobile region contribute to enhance the non-Fickian behavior. Adsorption heterogeneity is the major contributor to the non-Fickian behavior. The more violent anomalous behavior can be related to the higher retardation. Our results reveal the non-Fickian characteristics of ammonia nitrogen which will provide useful insights for decision-makers in the assessment and management of groundwater pollution.
KeywordsAmmonia nitrogen Vadose zone Non-Fickian dispersion CTRW-TPL model Adsorption heterogeneity
This research reported here was funded by the National Natural Science Foundation of Jilin Province with “Study on the process of water and salt nitrogen mutual feeding in water field ecosystem of soda-saline soil area” (20150101116JC) and the project of Northeast Electric Power Design Institute with “Study on the migration of pollutant components in coal-fired power plant of Northeast Electric Power Design Institute” (DG1-G01-2016).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Abdulgawad F, Bockelmann EB, Sapsford D, Williams K, Falconer R (2008) Ammonium ion adsorption on clay and sand under freshwater and seawater conditions. In: 16th IAHR-APD Congress and 3rd Symposium of IAHR-ISHS, Nanjing, jiangsu, China, 2008. p 6Google Scholar
- Bear J (1972) Dynamics of fluids in porous media. American Elsevier, New YorkGoogle Scholar
- Berkowitz B, Scher H, Cortis A, Dentz M (2006) Modeling non-Fickian transport in geological formations as a continuous time random walk. Rev Geophys 44. https://doi.org/10.1029/2005rg000178
- Brain B, Georg K, Genndy M, Harvey S (2001) Application of continuous time random walk theory to tracer test measurements in fractured and heterogeneous porous media. Ground Water 39:593–604. https://doi.org/10.1111/j.1745-6584.2001.tb02347.x CrossRefGoogle Scholar
- Bromly M, Hinz C (2004) Non-Fickian transport in homogeneous unsaturated repacked sand. Water Resour Res 40. https://doi.org/10.1029/2003wr002579
- Chakraborty P, Meerschaert MM, Lim CY (2009) Parameter estimation for fractional transport: a particle-tracking approach. Water Resour Res 45. https://doi.org/10.1029/2008wr007577
- Clothier BE, Kirkham MB, McLean JE (1992) In situ measurement of the effective transport volume for solute moving through soil. Soil Sci Soc Am J 56:733–736. https://doi.org/10.2136/sssaj1992.03615995005600030010x CrossRefGoogle Scholar
- Cortis A, Harter T, Hou L, Atwill ER, Packman AI, Green PG (2006) Transport of Cryptosporidium parvum in porous media: long-term elution experiments and continuous time random walk filtration modeling. Water Resour Res 42. https://doi.org/10.1029/2006wr004897
- Ekeleme AC, Agunwamba JC (2018) Experimental determination of dispersion coefficient in soil. Emerg Sci J 2. https://doi.org/10.28991/esj-2018-01145
- Hui L (2014) The characteristic and influence factors of ammonia-nitrogen adsorption desorption in the loess. Dissertation, Changfluence factorGoogle Scholar
- Jellali S, Diamantopoulos E, Kallali H, Bennaceur S, Anane M, Jedidi N (2010) Dynamic sorption of ammonium by sandy soil in fixed bed columns: evaluation of equilibrium and non-equilibrium transport processes. J Environ Manage 91:897–905. https://doi.org/10.1016/j.jenvman.2009.11.006 CrossRefGoogle Scholar
- Rezanezhad F, Kleimeier C, Milojevic T, Liu H, Weber TKD, Van Cappellen P, Lennartz B (2017) The role of pore structure on nitrate reduction in peat soil: a physical characterization of pore distribution and solute transport. Wetlands 37:951–960. https://doi.org/10.1007/s13157-017-0930-4 CrossRefGoogle Scholar
- Simunek J, Jacques D, Langergraber G, Bradford SA, Sejna M, van Genuchten MT (2013) Numerical modeling of contaminant transport using HYDRUS and its specialized modules. J Indian Inst Sci 93:265–284Google Scholar
- Tyukhova A, Dentz M, Kinzelbach W, Willmann M (2016) Mechanisms of anomalous dispersion in flow through heterogeneous porous media. Phys Rev Fluids 1. https://doi.org/10.1103/PhysRevFluids.1.074002
- WHO (2003) Ammonia in drinking-water background document for preparation of WHO guidelines for drinking-water quality. World Health OrganizationGoogle Scholar