Transport of gypsum in gypsiferous-calcareous soil under saturated and unsaturated water conditions

Other Title(s)

انتقال الجبس في تربة جبسية كلسية تحث ظروف مائية مشبعة و غير مشبعة

Joint Authors

Shihab, Ramzi Muhammad
Mahdi, Abd al-Latif Sabbar

Source

مجلة تكريت للعلوم الزراعية

Publisher

Tikrit University College of Agriculture

Publication Date

2018-12-31

Country of Publication

Iraq

No. of Pages

12

Main Subjects

Agriculture

Topics

• Gypsum
• Tikrit
• Gypsiferous soils
• Calcareous soils

English Abstract

This study was carried out to predict gypsum transport in a Gypsiferous - Calcareous soil profile by defining transport parameters by using the ConvectionDispersion Equation (CDE) model under saturated and unsaturated soil water flow conditions.

A site was selected in the fields of the College of Agriculture, University of Tikrit, where a soil profile was prepared in this site at a depth of 1.0m and the gypsum was measured for different depths.

Gypsum content at depths of 0-30cm (G1), 30-60cm (G2) and 60-90cm (G3) were 65, 130 and 240gkg-1 respectively.

The soil columns were leached by river water after saturation from the bottom by maintaining a column of water (0.01m) at the surface soil.

Additionally, intermittent ponding was imposed to soil columns in a 10.0 pore volume divided into four samples portions of the effluent and collected during leaching for measuring gypsum content.

The period between each two portions was 7 days.

The leachates were collected from the bottom of both continuous and intermittent leaching processes where density and pv were measured.

The gypsum breakthrough curves were constructed and CDE model was used to find the best use between measured and estimated values using MathCad software.

Peclet number (P) and correlation coefficient (r) were determined by changing the values of each of them by trial and error method until a higher correlation between the measured and estimated values depend on the highest value of the determination factor, r2 ,and r parameters.

Moreover, the Dispersion Coefficient (D) and Pore Water Velocity (v) were calculated.

The results showed that the effect of P was small and the effect of R was very large.

Furthermore, the v value increased as the gypsum content enhanced and D value was very high.

When D value increase and P value decrease, it means that the dispersion mechanism is dominant at the expense of the diffusion mechanism.

Also the gypsum solubility leads to the soil collapse and the closure of its pores.

The results also showed that CDE equation was efficient in describing the gypsum transmission and its movement.

The CDE equation gave a good correlation to describe the gypsum breakthrough curves and the ability to predict the gypsum movement and its transition with the gypsum soil leachate.

Data Type

Conference Papers

Record ID

BIM-922133

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