Modelling uranium leaching from agricultural soils to groundwater as a criterion for comparison with complementary safety indicators

2006 ◽  
Vol 932 ◽  
Author(s):  
D. Jacques ◽  
J. Šimůnek ◽  
D. Mallants ◽  
M.Th. van Genuchten
Keyword(s):  
Soil Profile ◽  
Reactive Transport ◽  
Transport Model ◽  
Agricultural Soils ◽  
Solid Phase ◽  
Water Flux ◽  
Fertilizer Application ◽  
Mineral Fertilizers ◽  
Deep Soil ◽  
Long Time

ABSTRACTNaturally occurring radionuclides can also end up in soils and groundwater due to human practices, such as application of certain fertilizers in agriculture. Many mineral fertilizers, particularly (super)phosphates, contain small amounts of 238U and 230Th which eventually may be leached from agricultural soils to underlying water resources. Field soils that receive P-fertilizers accumulate U and Th and their daughter nuclides, which eventually may leach to groundwater. Our objective was to numerically assess U migration in soils. Calculations were based on a new reactive transport model, HP1, which accounts for interactions between U and organic matter, phosphate, and carbonate. Solid phase interactions were simulated using a surface complexation module. Furthermore, all geochemical processes were coupled with a model accounting for dynamic changes in the soil water content and the water flux. The capabilities of the code in calculating natural U fluxes to groundwater were illustrated using a semi-synthetic 200-year long time series of climatological data for Belgium. Based on an average fertilizer application, the input of phosphate and uranium in the soil was defined. This paper discusses calculated U distributions in the soil profile as well as calculated U fluxes leached from a 100-cm deep soil profile. The calculated long-term leaching rates originating from fertilization are significantly higher after 200 years than estimated release rates from lowlevel nuclear waste repositories.

scholarly journals Reactive transport model of kinetically controlled celestite to barite replacement

2021 ◽  
Vol 56 ◽  
pp. 57-65
Author(s):  
Morgan Tranter ◽  
Maria Wetzel ◽  
Marco De Lucia ◽  
Michael Kühn
Keyword(s):  
Reactive Transport ◽  
Oil And Gas ◽  
Prediction Models ◽  
Transport Model ◽  
Solid Phase ◽  
A Priori ◽  
Dissolution Kinetics ◽  
Input Concentration ◽  
Geochemical Model ◽  
The Impact

Abstract. Barite formation is of concern for many utilisations of the geological subsurface, ranging from oil and gas extraction to geothermal reservoirs. It also acts as a scavenger mineral for the retention of radium within nuclear waste repositories. The impact of its precipitation on flow properties has been shown to vary by many orders of magnitude, emphasising the need for robust prediction models. An experimental flow-through column setup on the laboratory scale investigating the replacement of celestite (SrSO4) with barite (BaSO4) for various input barium concentrations was taken as a basis for modelling. We provide here a comprehensive, geochemical modelling approach to simulate the experiments. Celestite dissolution kinetics, as well as subsequent barite nucleation and crystal growth were identified as the most relevant reactive processes, which were included explicitly in the coupling. A digital rock representation of the granular sample was used to derive the initial inner surface area. Medium (10 mM) and high (100 mM) barium input concentration resulted in a comparably strong initial surge of barite nuclei formation, followed by continuous grain overgrowth and finally passivation of celestite. At lower input concentrations (1 mM), nuclei formation was significantly less, resulting in fewer but larger barite crystals and a slow moving reaction front with complete mineral replacement. The modelled mole fractions of the solid phase and effluent chemistry match well with previous experimental results. The improvement compared to models using empirical relationships is that no a-priori knowledge on prevailing supersaturations in the system is needed. For subsurface applications utilising reservoirs or reactive barriers, where barite precipitation plays a role, the developed geochemical model is of great benefit as only solute concentrations are needed as input for quantified prediction of alterations.

scholarly journals Effect of long-term fertilizer application on yield and concentrations of elements (N, P, K, Ca, Mg, As, Cd, Cu, Cr, Fe, Mn, Ni, Pb, Zn) in grain of spring barley

2013 ◽  
Vol 59 (No. 7) ◽  
pp. 329-334 ◽  
Author(s):  
M. Hejcman ◽  
M. Berková ◽  
E. Kunzová
Keyword(s):  
Agricultural Soils ◽  
Spring Barley ◽  
Farmyard Manure ◽  
Mineral Fertilizer ◽  
Fertilizer Application ◽  
Barley Grain ◽  
Mineral Fertilizers ◽  
Risk Elements ◽  
Application Rates

Little attention has been paid to the effect of long-term fertilizer application on concentrations of elements in grain of barley produced on the metal non-contaminated agricultural soil. In 2010, we analyzed yield and concentrations of elements in grain of spring barley in unfertilized control, mineral fertilizer application (N<sub>4</sub>P<sub>2</sub>K<sub>2</sub> &ndash; 70, 60 and<br />100 kg N, P and K per ha) and combinations of farmyard manure or poultry litter with mineral fertilizer (FMN<sub>4</sub>P<sub>2</sub>K<sub>2</sub> and PLN<sub>4</sub>P<sub>2</sub>K<sub>2</sub>) treatments in the Ruzyně Fertilizer Experiment established on Luvisol in 1955 in Prague (Czech Republic). The yield of grain ranged from 4.03 to 9.74 t/ha in the control and FMN<sub>4</sub>P<sub>2</sub>K<sub>2</sub> treatment. There was a positive effect of fertilizer application on concentrations of nitrogen, phosphorusand potassium, but no effect on concentrations of calcium and magnesium. With the exception of iron, concentrations of micro (copper and zinc) and risk elements (arsenic, cadmium, chromium, lead, manganese and nickel) were not significantly affected by the fertilizer treatments. Long-term use of organic and mineral fertilizers with appropriate application rates does not represent any risk for contamination of barley grain by risk elements on mineral rich and metal non-contaminated agricultural soils.

Change of the redox potential in the profile of light grey forest surface-gleyed soil under different anthropogenic

2018 ◽  
Vol 2 (95) ◽  
pp. 26-29
Author(s):  
O.S. Gavrishko ◽  
Yu.M. Olifir ◽  
T.V. Partyka
Keyword(s):  
Redox Potential ◽  
Mineral Fertilizer ◽  
Fertilizer Application ◽  
Soil Tillage ◽  
Mineral Fertilizers ◽  
Gleyed Soil ◽  
Agricultural Use ◽  
Fertilizer System ◽  
And Control ◽  
The Given

The results of studies of the change in redox potential in the profile of light gray forest surface-gleyed soil on variants with long-term agricultural use without applying fertilizers and mineral fertilizer system solely compared with the soil under the forest are presented. On the basis of the conducted analyzes it was established, that soil tillage without fertilizer application and with mineral fertilizer solely has a different effect on ROP in the profile. In the soil without fertilization (control) as compared to the forest a moderate oxidizing (514 mV) and slightly oxidizing (437 mV) processes are happening. Prolonged application of mineral fertilizers to the soil (N65R68K68) significantly reduced the redox potential of all genetic horizons compared with forest and control without fertilizers. For the given fertilizer system the highest values of ROP were obtained in arable HEgl and underarable HEgl layers: 426 mV and 416 mV respectively. Redox potential sharply decreases with the depth to 398-311 mV, which characterizes processes occurring in the soil profile, as weakly reducing and close to moderately reducing.

scholarly journals Reactive Transport Model of Sulfur Cycling as Impacted by Perchlorate and Nitrate Treatments

2016 ◽  
Vol 50 (13) ◽  
pp. 7010-7018 ◽  
Author(s):  
Yiwei Cheng ◽  
Christopher G. Hubbard ◽  
Li Li ◽  
Nicholas Bouskill ◽  
Sergi Molins ◽  
...  
Keyword(s):  
Reactive Transport ◽  
Transport Model ◽  
Sulfur Cycling ◽  
Reactive Transport Model

scholarly journals Mineralogical, numerical and analytical studies of the coupled oxidation of pyrite and coal

2003 ◽  
Vol 67 (2) ◽  
pp. 381-398 ◽  
Author(s):  
K. A. Evans ◽  
C. J. Gandy ◽  
S. A. Banwart
Keyword(s):  
Reactive Transport ◽  
Transport Model ◽  
Pyrite Oxidation ◽  
Spoil Heap ◽  
Reaction Fronts ◽  
Order Of Magnitude ◽  
Magnitude Variation ◽  
Discharge Chemistry ◽  
Analytical Expressions

Mineralogical, bulk and field leachate compositions are used to identify important processes governing the evolution of discharges from a coal spoil heap in County Durham. These processes are incorporated into a numerical one-dimensional advective-kinetic reactive transport model which reproduces field results, including gas compositions, to within an order of magnitude. Variation of input parameters allows the effects of incorrect initial assumptions on elemental profiles and discharge chemistry to be assessed. Analytical expressions for widths and speeds of kinetic reaction fronts are developed and used to predict long-term development of mineralogical distribution within the heap. Results are consistent with observations from the field site. Pyrite oxidation is expected to dominate O2 consumption in spoil heaps on the decadal timescale, although C oxidation may stabilize contaminants in effluents on the centennial scale.

Functional role of earthworms to control the hydraulic conductivity of constructed wetlands 

2021 ◽  
Author(s):  
Océane Gilibert ◽  
Dan Tam Costa ◽  
Sabine Sauvage ◽  
Didier Orange ◽  
Yvan Capowiez ◽  
...  
Keyword(s):  
Organic Matter ◽  
Hydraulic Conductivity ◽  
Constructed Wetlands ◽  
Hyporheic Zone ◽  
Riparian Zone ◽  
Water Flux ◽  
Sediment Surface ◽  
Deep Soil ◽  
The Impact ◽  
Organic Matter Input

&lt;p&gt;Wetlands are known for their natural service of water quality regulation. The hyporheic zones of the rivers filter and purify the surface water from the stream and infiltrated waters in soil nearby through the riparian zone. This purification service occurs because of a synergy between the substrate and its biodiversity (including plants, bacteria and other invertebrates). Our study deals with constructed wetlands (CW) as a nature-based solution mimicking wetlands water purification process, to purify wastewaters. The REUSE technology of CW is based on the use of specific layers of gravels and sands inside a close concrete structure, planted with specific sub-aquatic plants, where wastewaters or runoff of stormwaters are introduced to be filtered. The technology of Vertical Flow Constructed Wetlands (VFCW) reproduces the water flux observed in the riparian zone with a gravity flow of water. It is composed of reeds planted on a sandy layer (&amp;#216; 0-4 mm) and succession of gravel layers. This substrate can be saturated or unsaturated to reproduce the functioning of the hyporheic zone or the riparian zone respectively. By the time, the substrate is colonized by a community of bacteria producing biofilms which capture the residual organic matter from wastewaters to mineralize them. However, the VFCW substrates tend to clog over time due to the accumulation of organic matter and biofilms. Many studies consider earthworms as one of the solutions to alleviate this clogging, thanks to their burrows recreating macropores and preferential channels which help to improve the dispersion of water into the deep soil. The main goal of this study is to assess the impact of earthworm activities on the hydraulic conductivity of columns composed with the same substrate used in the VFCW. Different densities of earthworms (Eisenia fetida) were introduced (0, 100, 500, 1000 g of earthworms/m&amp;#178;) in these columns to be monitored for 37 days. The hydraulic conductivity was measured every 7 days, aside from day 23 with the addition of 40 g of peat bedding on column surfaces to simulate a high organic matter input. Columns with earthworm density superior to 500 g/m&amp;#178; shows an amelioration of their hydraulic conductivity after 21 days. These densities are also able to restore the hydraulic conductivity of the column in less than 7 days after the setting of clogged condition due to the organic matter input (peat bedding) at the sediment surface. This study showed that the burrowing activity of E. fetida improves the hydraulic flux of a sandy substrate and this impact is dependent on the earthworm density introduced. So, the addition of earthworms in the VFCW could serve as a prevention against clogging.&lt;/p&gt;

scholarly journals Glyphosate Transport in Two Louisiana Agricultural Soils: Miscible Displacement Studies and Numerical Modeling

Soil Systems ◽  
2018 ◽  
Vol 2 (3) ◽  
pp. 53 ◽  
Author(s):  
Joshua Padilla ◽  
H. Selim
Keyword(s):  
Transport Model ◽  
Agricultural Soils ◽  
Exchange Capacity ◽  
Miscible Displacement ◽  
Soil Environment ◽  
Linear Modeling ◽  
Primary Metabolite ◽  
Aminomethylphosphonic Acid ◽  
Displacement Experiments ◽  
Reaction Transport

Glyphosate (N-(phosphonomethyl) glycine) (GPS) is currently the most commonly used herbicide worldwide, and is generally considered as immobile in soils. However, numerous reports of the environmental occurrence of the herbicide coupled with recent evidence of human toxicity necessitate further investigation as to the behavior of GPS in the soil environment. Batch sorption studies along with miscible displacement experiments were carried out in order to assess the mobility of GPS in two Louisiana agricultural soils; Commerce silt loam and Sharkey clay. Batch results indicated a high affinity of both soils for solvated GPS, with greater affinity observed by the Sharkey soil. GPS sorption in the Commerce soil was most likely facilitated by the presence of amorphous Fe and Al oxides, whereas the high cation exchange capacity of the Sharkey soil likely allows for GPS complexation with surface exchangeable poly-valent cations. Miscible displacement studies indicate that GPS mobility is highly limited in both soils, with 3% and 2% of the applied herbicide mass recovered in the effluent solution from the Commerce and Sharkey soils, respectively. A two-site multi-reaction transport model (MRTM) adequately described GPS breakthrough from both soils and outperformed linear modeling efforts using CXTFIT. Analysis of extracted herbicide residues suggests that the primary metabolite of GPS, aminomethylphosphonic acid (AMPA), is more mobile in both soils, although both compounds are strongly retained.

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