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Accurate scheduling of bauxite residue (red mud) deposition time is required in order to prevent the risk of storage facility failure. This study was conducted to precisely determine the hydraulic parameters of bauxite residue and investigate the capability of HYDRUS to accurately estimate the residue moisture profile and the timing for its deposition. The hydraulic properties of the bauxite residue profile were determined by solving an inverse problem. A one-dimensional hydrological model (HYDRUS-1D) was validated using a 300 mm long column filled with bauxite residue and exposed to a dynamic lower boundary condition. After numerical validation, the model was used to simulate the moisture profile of bauxite residue under the climatic conditions of an alumina refinery site in Queensland, Australia, as well as other scenarios (i.e., high (300 mm) and small (1.7 mm) rainfall events of the site). This study showed that the HYDRUS model can be used as a predictive tool to precisely estimate the moisture profile of the bauxite residue and that the timing for the re-deposition of the bauxite residue can be estimated by understanding the moisture profile and desired shear strength of the residue. This study revealed that the examined bauxite residue approaches field capacity (water potential −10 kPa) after three days from a low rainfall event (<1.7 mm) and after eight days from an intense rainfall event (300 mm) at the time of disposal. This suggests that the bauxite residue can be deposited every four days after low rainfall events (as low as 1.7 mm) and every nine days after high rainfall events (as high as 300 mm) at the time of deposition, if bauxite residue experiences an initial drying period following deposition.
Mandana Shaygan; Brent Usher; Thomas Baumgartl. Modelling Hydrological Performance of a Bauxite Residue Profile for Deposition Management of a Storage Facility. Water 2020, 12, 1988 .
AMA StyleMandana Shaygan, Brent Usher, Thomas Baumgartl. Modelling Hydrological Performance of a Bauxite Residue Profile for Deposition Management of a Storage Facility. Water. 2020; 12 (7):1988.
Chicago/Turabian StyleMandana Shaygan; Brent Usher; Thomas Baumgartl. 2020. "Modelling Hydrological Performance of a Bauxite Residue Profile for Deposition Management of a Storage Facility." Water 12, no. 7: 1988.
Numerical modelling is a tool allowing the prediction of water flow and water balance based on material properties and time dependent input information at defined boundaries. Long time series are often required for a well informed assessment of the performance of a site. It has been shown that covers as a preferred option constructed in semi-arid and arid climates on mine sites to manage water flows and to prevent deep drainage have a characteristic bi-modal pore system largely caused by a large fraction of coarse rocks. Bi-modal water retention curves have been established for such covers which have proven to describe the response to precipitation with higher accuracy. Meteorological data as input information are in many cases only available on a daily basis if time series over decades are used for modelling. For a bi-modal pore system with often very high values for saturated hydraulic conductivity, a daily time-step may be to large to capture numerically the response in water flow. The objective of the presented work is the comparison of modelled deep drainage data for a specific cover design where hourly data are compared with daily input data. The latter were aggregated from the hourly information.
The results from the numerical modelling showed that for environments with high intensity rainfall events the calculated amount of deep drainage was by up to 10% smaller for the aggregated daily input data compared to the hourly data.
The presentation will inform which rainfall events contributed primarily to the difference in the water balance parameters and to which extent a generalisation can be made on the choice or requirement to choose an appropriate time step for specific climatic conditions.
Thomas Baumgartl; Mandana Shaygan. The effect of the choice of time resolution on the prediction of deep drainage rates in rocky covers. 2020, 1 .
AMA StyleThomas Baumgartl, Mandana Shaygan. The effect of the choice of time resolution on the prediction of deep drainage rates in rocky covers. . 2020; ():1.
Chicago/Turabian StyleThomas Baumgartl; Mandana Shaygan. 2020. "The effect of the choice of time resolution on the prediction of deep drainage rates in rocky covers." , no. : 1.
Soils in arid and semi-arid environments are threatened by salinization. A cost-effective and efficient way to reclaim saline land is through leaching. This will be most effective in situations where direct human impact is the cause for salinity, e.g., in environments affected by industrial use or land rehabilitation following mining. Irrigation, which is the most common means of achieving salt leaching, is not feasible for the reclamation of mine sites’ salt-affected soils located in remote areas, and thus, land reclamation largely relies on natural climatic conditions. This study was conducted to assess the effect of different climatic conditions of semi-arid environments on spatio-temporal salt leaching from brine-affected soil, and investigate the efficacy of the reduction of soil bulk density as a reclamation technique for saline land experiencing water scarcity. Three regions (represented by the Australian cities of Roma, Mount Isa, and Quilpie) representing semi-arid environments of Australia were selected, and their climatic scenarios (23 years) were applied to a validated HYDRUS-1D model. A brine-affected soil typical to Queensland, Australia, was chosen for this study. The investigations established that a greater number of individual high rainfall events resulted in a greater reduction of salinity in Roma (96%) and Mount Isa (93.31%) compared with Quilpie (58.75%), in which the soil salinity approached a level (−1) that was suitable for sustaining plant growth. Soil salinity reduced to 8 dS m−1 under the climatic conditions of the Quilpie region. This study also demonstrated that the success of salt leaching from a brine-affected soil is a consequence of a sensitive response to the depth of individual rainfall events rather than rainfall distribution and the total amount of rainfall, and is controlled by the physical properties of the soil. Where climatic conditions cannot solely assist with salt leaching, reclamation may be successful by reducing soil bulk density.
Mandana Shaygan; Thomas Baumgartl. Simulation of the Effect of Climate Variability on Reclamation Success of Brine-Affected Soil in Semi-Arid Environments. Sustainability 2020, 12, 371 .
AMA StyleMandana Shaygan, Thomas Baumgartl. Simulation of the Effect of Climate Variability on Reclamation Success of Brine-Affected Soil in Semi-Arid Environments. Sustainability. 2020; 12 (1):371.
Chicago/Turabian StyleMandana Shaygan; Thomas Baumgartl. 2020. "Simulation of the Effect of Climate Variability on Reclamation Success of Brine-Affected Soil in Semi-Arid Environments." Sustainability 12, no. 1: 371.
Coal mine spoils have the potential to create environmental impacts, such as salt load to surrounding environments, particularly when exposed to weathering processes. This study was conducted to understand the effect of physical and chemical weathering on the magnitude, rate, and dynamics of salt release from different coal mine spoils. Five spoil samples from three mines in Queensland were sieved to three different particle size fractions (6 mm). Two samples were dispersive spoils, and three samples were nondispersive spoils. The spoils were subjected to seven wet–dry cycles, where the samples were periodically leached with deionised water. The rate, magnitude, and dynamics of solutes released from spoils were spoil specific. One set of spoils did not show any evidence of weathering, but initially had higher accumulation of salts. In contrast, broad oxidative weathering occurred in another set of spoils; this led to acid generation and resulted in physical weathering, promoting adsorption–desorption and dissolution and, thus, a greater release of salts. This study indicated that the rate and magnitude of salt release decreased with increasing particle size. Nevertheless, when the spoil is dispersive, the degree of weathering manages salt release irrespective of initial particle size. This study revealed that the long-term salt release from spoils is not only governed by geochemistry, weathering degree, and particle size but also controlled by the water/rock ratio and hydrological conditions of spoils.
Melinda Hilton; Mandana Shaygan; Neil McIntyre; Thomas Baumgartl; Mansour Edraki. The Effect of Weathering on Salt Release from Coal Mine Spoils. Minerals 2019, 9, 760 .
AMA StyleMelinda Hilton, Mandana Shaygan, Neil McIntyre, Thomas Baumgartl, Mansour Edraki. The Effect of Weathering on Salt Release from Coal Mine Spoils. Minerals. 2019; 9 (12):760.
Chicago/Turabian StyleMelinda Hilton; Mandana Shaygan; Neil McIntyre; Thomas Baumgartl; Mansour Edraki. 2019. "The Effect of Weathering on Salt Release from Coal Mine Spoils." Minerals 9, no. 12: 760.
Poor soil physical conditions associated with low hydraulic conductivity and infiltration can limit salt leaching and reclamation; hence, land revegetation. Soil physical amendments such as wood chips and fine sand may be used to remediate the soil physical conditions and improve salt leaching, thus assisting with revegetation. To evaluate the success of soil amendments for the reclamation and revegetation of a saline-sodic soil under a typical climatic condition of a semi-arid environment, a water and solute transport model (HYDRUS-1D) was used. Synthetic climatic scenarios were generated using LARS-WG. Soil profiles (1 m depth) amended separately with 20% wood chips and 40% fine sand at the surface (0–10 cm) were defined for the simulation. A non-amended soil profile, which had physical properties of a disturbed soil, was used as a control. Salt leaching was more successful in the non-amended soil profile compared with the amended soil profiles. The likelihood and the success of Atriplex halimus L. seed germination were also higher in the non-amended soil (67.7%) compared with wood chips (13.98%) and fine sand (6.7%) amended soils. This study indicates that the addition of 20% wood chips and 40% fine sand to the depth of 10 cm of a saline-sodic soil may not be an effective approach for reclamation and revegetation under the semi-arid climatic conditions. This study suggests that a reduction in soil bulk density is sufficient to provide suitable conditions for successful land reclamation and revegetation in the investigated climatic conditions.
Mandana Shaygan; Lucy Reading; Sven Arnold; Thomas Baumgartl. Modeling the effect of soil physical amendments on reclamation and revegetation success of a saline-sodic soil in a semi-arid environment. Arid Land Research and Management 2018, 32, 379 -406.
AMA StyleMandana Shaygan, Lucy Reading, Sven Arnold, Thomas Baumgartl. Modeling the effect of soil physical amendments on reclamation and revegetation success of a saline-sodic soil in a semi-arid environment. Arid Land Research and Management. 2018; 32 (4):379-406.
Chicago/Turabian StyleMandana Shaygan; Lucy Reading; Sven Arnold; Thomas Baumgartl. 2018. "Modeling the effect of soil physical amendments on reclamation and revegetation success of a saline-sodic soil in a semi-arid environment." Arid Land Research and Management 32, no. 4: 379-406.
Brine, produced as a by‐product of oil extraction, when contained in evaporation ponds can cause soil salinization in the vicinity of these ponds. Native halophytes may assist revegetation and rehabilitation of these salt‐affected soils. This study was conducted to investigate the revegetation and rehabilitation potential of brine‐affected land using native halophytes (Tecticornia pergranulata (J.M.Black) K.A.Sheph. & Paul G.Wilson, Sclerolaena longicuspis (F.Muell.) A.J.Scott and Frankenia serpyllifolia Lindl). Soil samples from adjacent bare and vegetated areas of brine‐affected land were compared to assess the physico‐chemical properties associated with the vegetation cover. The salt contents of the halophytes, plant bioaccumulation, bioconcentration, and translocation factors were measured to evaluate remediation capacity of the species. We hypothesized that the halophytes reduce the ions' concentrations and thus soil salinity and sodicity. The examined halophytes were associated with a reduction in salinity and sodicity by an average of 38.5% and 33% in the top 10 cm of the soil, respectively. T. pergranulata had the highest shoot Na+ content (98 g/kg dry wt), bioaccumulation (14.21), and translocation (23.09) factors for Na+ that indicated the higher remediation potential of this species. Despite the high remediation potential of the examined species, halophytes are not able to reduce the salt content of the landscape to create conditions for the growth of glycophytes. However, the salt‐affected land can be revegetated by halophytes, and halophytes probably provide a stable vegetation cover for the landscape in ecological succession. An improvement in soil physical properties is required for revegetation success.
Mandana Shaygan; David Mulligan; Thomas Baumgartl. The potential of three halophytes (Tecticornia pergranulata , Sclerolaena longicuspis , and Frankenia serpyllifolia ) for the rehabilitation of brine-affected soils. Land Degradation & Development 2018, 29, 2002 -2014.
AMA StyleMandana Shaygan, David Mulligan, Thomas Baumgartl. The potential of three halophytes (Tecticornia pergranulata , Sclerolaena longicuspis , and Frankenia serpyllifolia ) for the rehabilitation of brine-affected soils. Land Degradation & Development. 2018; 29 (6):2002-2014.
Chicago/Turabian StyleMandana Shaygan; David Mulligan; Thomas Baumgartl. 2018. "The potential of three halophytes (Tecticornia pergranulata , Sclerolaena longicuspis , and Frankenia serpyllifolia ) for the rehabilitation of brine-affected soils." Land Degradation & Development 29, no. 6: 2002-2014.
Poor soil physical conditions such as low hydraulic conductivity can limit salt depletion from surface soil. Altering the pore system by addition of organic and inorganic amendments may improve salt leaching as a reclamation strategy. Column studies were conducted to investigate salt leaching in amended and non-amended soil profiles. A one-dimensional water and solute transport model (HYDRUS-1D) was also assessed for its applicability to simulate salt leaching for amendment strategy. Columns of length 300mm were filled with saline-sodic soil at the lower end (100–300mm) and then covered with soil amended with 40% (wt/wt) fine sand and 20% (wt/wt) wood chips, separately. A control column was filled with saline-sodic soil only. One rainfall scenario typical for a location in south-west Queensland (Australia) was applied to the columns. Water potentials were monitored using tensiometers installed at three depths: 35, 120 and 250mm. The concentrations of individual cations (Na+, Ca2+, Mg2+ and K+), electrical conductivity and sodium adsorption ratio of the soil solutions were also monitored for the investigated depths. A reduction in surface salinity (up to 28.5%) was observed in the amended soil profiles. This study indicated that the addition of wood chips to surface soil improved salt leaching under the tested conditions. The simulation successfully predicted both hydrology and chemistry of the columns. This study also concluded that HYDRUS-1D is a powerful tool to simulate salt leaching in the amended soil profiles, and can be applied to predict the success of amendment strategy under natural climatic conditions.
Mandana Shaygan; Thomas Baumgartl; Sven Arnold; Lucy Reading. The effect of soil physical amendments on reclamation of a saline-sodic soil: simulation of salt leaching using HYDRUS-1D. Soil Research 2018, 56, 829 .
AMA StyleMandana Shaygan, Thomas Baumgartl, Sven Arnold, Lucy Reading. The effect of soil physical amendments on reclamation of a saline-sodic soil: simulation of salt leaching using HYDRUS-1D. Soil Research. 2018; 56 (8):829.
Chicago/Turabian StyleMandana Shaygan; Thomas Baumgartl; Sven Arnold; Lucy Reading. 2018. "The effect of soil physical amendments on reclamation of a saline-sodic soil: simulation of salt leaching using HYDRUS-1D." Soil Research 56, no. 8: 829.
Mandana Shaygan; Thomas Baumgartl; Sven Arnold. Germination of Atriplex halimus seeds under salinity and water stress. Ecological Engineering 2017, 102, 636 -640.
AMA StyleMandana Shaygan, Thomas Baumgartl, Sven Arnold. Germination of Atriplex halimus seeds under salinity and water stress. Ecological Engineering. 2017; 102 ():636-640.
Chicago/Turabian StyleMandana Shaygan; Thomas Baumgartl; Sven Arnold. 2017. "Germination of Atriplex halimus seeds under salinity and water stress." Ecological Engineering 102, no. : 636-640.
Highlights\ud \ud - A slower water movement is associated with a greater salt leaching efficiency.\ud \ud - A greater rate of cation exchange can increase salt leaching.\ud \ud - Addition of bentonite can improve the reduction of soil salinity.\ud \ud Abstract\ud \ud Saline-sodic soils may be reclaimed through the addition of amendments to alter the soil pore system and hydraulic functions, therefore allowing salts to be leached from the soil. For the purpose of investigating the suitability of specific amendments for improving leaching and reclamation, soil percolation column studies were conducted to assess the influence of amendments on cation exchange, the potential for the release of cations and changes in hydraulic conductivity of the soil. A fine textured saline-sodic soil amended separately with 20% wood chips (wt/wt), 40% fine sand (wt/wt) and 2.5% bentonite (wt/wt) was used for this study as well as a non-amended soil as a control. The impact of amendments was evaluated by continuous leaching of the soil substrates with deionized water until the hydraulic conductivity and leachate chemistry stabilised. The bentonite amended soil had a greater increase (15.9 cmolc kg−1) in exchangeable Ca2+ and a higher reduction in exchangeable Na+ (12.29 cmolc kg−1) after the final leaching due to a greater rate of cation exchange for this soil substrate. The bentonite amended soil also had a greater reduction (92%) in Na+ content compared with the other soil substrates. The hydraulic conductivity of all soil substrates improved during leaching although the hydraulic conductivity of bentonite amended soil reduced after three pore volumes of leaching. This study suggests that a slower water movement (an increased percolation time) and a greater rate of cation exchange were associated with the greater leaching efficiency. Therefore, addition of bentonite improves and accelerates the reduction of salinity and sodicity
Mandana Shaygan; Lucy Reading; Thomas Baumgartl. Effect of physical amendments on salt leaching characteristics for reclamation. Geoderma 2017, 292, 96 -110.
AMA StyleMandana Shaygan, Lucy Reading, Thomas Baumgartl. Effect of physical amendments on salt leaching characteristics for reclamation. Geoderma. 2017; 292 ():96-110.
Chicago/Turabian StyleMandana Shaygan; Lucy Reading; Thomas Baumgartl. 2017. "Effect of physical amendments on salt leaching characteristics for reclamation." Geoderma 292, no. : 96-110.