Majed Abu-Zreig

Effect of Application of Surfactants on Hydraulic Properties of Soils

Abstract This study explores the effect of surfactants, commonly found in detergents, on the hydraulic properties of soils. The soil properties examined included hydraulic conductivity, infiltration characteristics, and effective suction at the wetting front, capillary rise and soil penetrability. Two agricultural soils—a loam and a sandy loam, and three surfactants—one anionic surfactant (Sulphonic) and two non-ionic surfactants (Rexol and Rexonic), were used in the study. Changes in hydraulic properties with the application of surfactants were compared with properties obtained with deionised water (control). The results showed that Sulphonic, the anionic surfactant, had a significant effect on hydraulic properties of both soils. Applications of Sulphonic caused decreases in the capillary rise and penetrability, and an increase in the solid–liquid contact angle, shape factor and sorptivity. Except for a slight decrease in hydraulic conductivity resulting from the application of Rexol, the non-ionic surfactants did not reveal significant impact on the hydraulic characteristics of test soils.

Effect of surfactants on sorption of atrazine by soil

This study investigates the effect of synthetic wastewater containing surfactants on the sorption of atrazine using an equilibrium batch technique. Laboratory experiments were conducted on three soils with two non-ionic (Rexol and Rexonic) surfactants and one anionic (Sulphonic) surfactant, specifically manufactured for the detergent industry. Four sets of experiments were conducted to examine the influence of surfactants on the equilibrium time of atrazine sorption, to explore the effect of surfactant concentration, pH and type of surfactant on the amount of atrazine sorbed and to determine sorption isotherms of atrazine in the presence of surfactants. The results indicate that the application of Sulphonic results in dramatic increase in the adsorption of atrazine on to soils, the increase being directly proportional to the concentration of the surfactant. Application of the Sulphonic surfactants with a concentration of 3000 mg/l can result in a significant increase in Kd values of atrazine for loam and sandy loam soils. On the other hand, the effect of non-ionic surfactants depends on their concentration. Generally, non-ionic surfactants can result in a slight increase in atrazine sorption at high concentration, an exception being Rexol on sandy loam soil. At low concentrations, non-ionic surfactants have shown a tendency to decrease atrazine sorption.

Influence of olive mills solid waste on soil hydraulic properties

The annual production of olive fruits in Jordan is about 105,000 tons producing more than 80,000 tons of solid waste annually. Olive mills solid waste (OMW) contains 94% organic matter and, therefore, can be highly beneficial to agricultural soil. However, olive waste contains oil that may increase soil hydrophobicity and decrease water retention and infiltration rate. In this research, the impact of OMW on water retention, saturated and unsaturated hydraulic conductivity, and capillary rise of three soils, loam, clay loam, and dune sand, has been investigated under laboratory conditions. Application of OMW resulted in an increase in water retention and saturated hydraulic conductivity but caused a decrease in capillary rise and unsaturated hydraulic conductivity for all soils tested. The increase in water retention has been observed at all levels of pressure potential and was significantly different at 3 bars or higher. The highest increase in saturated hydraulic conductivity occurred at 4% application rate at which about 300%, 200%, and only 12% increase was observed for loam, clay loam, and dune sand, respectively. Application of OMW caused a significant decrease in the capillary rise ranging from 11.5% for dune sand to 70% for clay loam soil. Capillary rises were inversely related to the OMW treatment level for all soils tested.

Influence of heat treatment on the behavior of clayey soils

Abstract This study examines the effect of temperature under laboratory conditions of three clayey soils collected from northern Jordan. Soils were subjected to four temperature levels, i.e. 100, 200, 300 and 400 °C. Various soil properties were studied including Atterberg limits, particle size distribution, optimum water content, maximum dry density, swelling potential, and unconfined compressive strength. Experimental results revealed that heat treatment higher than 100 °C resulted in a decrease in liquid and plastic limits, optimum water content, unconfined compressive strength, and swelling pressure of soils tested. However, maximum dry density increased slightly with an increase in temperature to reach a maximum value of 14.3 kN/m 3 at 400 °C for soil-1 compared to 12.9 kN/m 3 at ambient temperature. Heating the clayey soils at 400 °C decreased the liquid limit, plastic limit, optimum water content, swelling pressure, and unconfined compressive strength by 80%, 100%, 65%, 94%, and 100%, respectively, in average compared to soil specimens at ambient temperature.

Effect of Interstitial Velocity on the Adsorption of Bacteria onto Soil

The adsorption of bacteria onto soil is affected by the physical and chemical characteristics of the soil and water, the size and morphology of the bacterial cells, and the water-flow characteristics in the soil. The present study focuses on the latter factor by investigating the effect of the interstitial velocity on the adsorption of bacteria onto soil. Columns of 10 cm diameter and 130 cm height, respectively, were packed with a sandy soil. The columns were saturated with water containing nalidixic acid-resistant Escherichia coli as a bio-tracer at three different pH levels. The columns were maintained at 20°C for 24 h before connecting the column outlet to its inlet by a pump in a closed loop. Water containing the biotracer was re-circulated through the column for another 24 h at three different interstitial velocities. Water samples were taken from a sampling tap connected to the pump at 4-h intervals. These samples were analyzed to determine the biotracer concentration. The results show that more biotracer cells were retained in the soil at the lower interstitial velocity. The higher interstitial velocity resulted in higher shear forces which caused more desorption of the biotracer cells from the surfaces of the soil particles. Bacterial adsorption was higher at the acidic pH value. The survival of the biotracer cells in soil solution was also tested at three different pH levels. The results show that no decline in the biotracer concentration occurred during the test period.

Spatio-Temporal Variability of Evapotranspiration over the Kingdom of Saudi Arabia

Climate change and variability is receiving much attention recently. Changes in the world temperature and other natural phenomenon such as rainfall variability are being considered as indicators to climate change. These changes can have significant effect on water resources and therefore on the livelihood of society especially in water scarce countries such Saudi Arabia. The Kingdom of Saudi Arabia suffers a chronic water scarcity, despite the fact that the agricultural sector consumes around 90% of the water budget in the kingdom. The objective of this article is to study the variability in reference evapotranspiration (ETo) demand over the kingdom during the period from 1980 to 2008 using Penman-Monteith formula and to identify possible changes in the ETo as an indicator to climate change in the region. Studying ETo can be an incomparable indicator for climate change because it involves various parameters including temperature, humidity, and wind speed. Identifying changes in ETo can also help in future planning of agriculture-water projects and identify lower and higher ETo zones for proper planning and management of agricultural projects in arid region. Results indicated that the average ETo varied from 5 mm/d in January to more than 15 mm/d in July with extreme value ranged from as low as 1.6 to 30 mm/d. The lowest ETo values were found in the southern region of the Kingdom during the month of November to February and starts to shift to the western region from the month of March to October. The results also indicated that the annual maximum and minimum daily averages of ETo steadily increased over the study period. The ETo annual daily average had increased from about 9.6 mm/d in 1980 to as high as 10.5 mm/d in 2008. Data analysis also revealed that the percentage areas of the Kingdom with high values of ETo depth, greater than 4000 mm/year, have also steadily increased in the study period from 25% to about 40%. On the other hand, areas having lower ETo values, less than 3600 mm/year have decreased over the studied area from about 30% in 1980 to as low as 12% of the kingdom total area. These results indicated clearly an increasing trend in the ETo over Saudi Arabia.

Soil Erosion Control and Moisture Conservation of Arid Lands with Stone Cover

Soil moisture conservation and combating soil erosion on agricultural fields are the highest priorities for crop production in arid lands. In this research, the effect of land application of rock fragments on runoff, soil loss, and vegetative cover on a silt loam soil has been tested under natural rainfall conditions. Field plots of 2 m wide by 10 m long were prepared in two locations with a deposit installed at the downstream end of the plots to collect runoff and sediments after each storm during the 2004/2005 winter season. Three treatments were used in the experiments in duplicates including plots covered with 5% and 15% stone and a control. Experimental results showed that rock fragments were highly effective in reducing runoff and soil loss. Runoff depth from plots covered with rock fragments at a rate of 5% and 15% was reduced by 17% and 30% compared to the control, respectively. The corresponding reductions in soil loss for both stone treatment levels were as high as 35% and 53%, respectively. The average soil moisture measured at the center of the plots during the entire season was always higher for stone treated plots and increased with stone coverage percentage compared to control. Consequently, vegetative cover was higher in the plots with 5% rock fragments cover. For higher stone coverage of 15%, rock fragments occupy more soil surface area and, therefore, reduce the space available for vegetation.

Erosion Control of Arid Land in Jordan with Two Anionic Polyacrylamides

Field experiments were conducted to test the influence of two types of anionic polyacrylamide (PAM) on soil erosion and runoff of sloping land in Jordan under natural rainfall conditions. The two PAMs used in this study, Superfloc A-836 and Superfloc A-870, varied widely in molecular weight ranging qualitatively from high, 15 Mg/mol, to very low and surface charge from 20% to 70%, respectively. Fourteen 2-m × 10-m field plots with a 12% slope gradient were constructed in the field. Collection barrels were installed at the end of plots to monitor the amount of runoff and sediment loss after each storm. The PAMs were applied at two rates of 10 and 30 kg/ha plus a control. The experimental design includes seven treatments with two replicates. Experimental results showed that PAM was effective in reducing runoff and soil loss at the two application rates. Application of A-836 reduced runoff and sediment loss by 23% and 35%, respectively, compared to control and the corresponding average decrease in runoff and soil loss for A-870 were 16% and 8%, respectively. Differences in runoff among PAM-treated plots at 10 and 30 kg/ha were negligible, but soil loss was slightly lower in the 30 kg/ha PAM-treated plots. Polyacrylamide application increased dry matter crop yield, and the application rate seemed to have a greater influence than the PAM type. The average dry matter yield for both PAMs at 30 kg/ha and 10 kg/ha increased by 56% and 35%, respectively, compared to control.

Influence of surfactants on leaching of atrazine through soil columns

Laboratory experiments were conducted to examine the effect of surfactants, two non‐ionic and one anionic commonly used in detergents, on transport of atrazine through loam and sandy loam soils under saturated conditions. The moment techniques have been used to quantify the effects of surfactants on the mass of atrazine leached, mean time of elution, dispersion and skewness of atrazine breakthrough. Results indicated that application of the anionic surfactant had a dramatic impact on atrazine movement through both soils. The anionic surfactant decreased the amount of atrazine leached from 78% in deionized water to 52% for Elora loam and from 75% to only 13% in sandy soil, respectively. Land application of anionic surfactant also increased the mean time of elution by 142% and 431% compared to deionized water for loam and sandy loam soils, respectively. However, application of non‐ionic surfactants increases atrazine leaching. The percentage of atrazine eluted in the presence of Rexonic at 3000 mg/L and 200 mg/L and Rexol at 200 mg/L were 87%, 80% and 84%, respectively compared to only 76% in deionized water. Results also indicated that application of surfactants results in a physio‐chemical changes in soil matrix that affects atrazine sorption. Non‐equilibrium conditions seemed to govern atrazine movement in the presence of surfactants as noticed from the long tailing and double peaks in the breakthrough curves.

CHANGES IN CLAY SWELLING AND SHEAR STRENGTH PROPERTIES WITH DIFFERENT SAMPLE PREPARATION TECHNIQUES

This paper presents the effect of compaction methods on soil swell pressure, unconfined compressive strength, and swell potential of three types of soils in Jordan. Undisturbed and disturbed soil samples were collected from the field and used for this study. Compacted soil specimens were prepared using dynamic compaction, static compaction, and kneading compaction. Swell potential test, swelling pressure test, and unconfined compression test were conducted on identical samples compacted by different methods, and having similar initial conditions to the undisturbed samples. Other sets of experiments were also conducted to examine the influence of initial water content on swell pressure and unconfined compressive strength under different compaction techniques. Results indicated that the undisturbed samples have the highest swelling pressure and swell potential values followed by dynamic compaction, while kneading compaction gave the lowest values for the three soils. For the same soil, it has been found that the swelling pressures of the undisturbed samples were 1.5, 1.96, and 3.07 times of that for the dynamic, static, and kneading compaction, respectively. Similar trends were obtained with regard to unconfined compressive strength and swell potential. The unconfined compressive strengths of the undisturbed samples were 1.35, 1.6, and 2.53 times higher than that of the soil specimen compacted according to the dynamic, static, and kneading procedures, respectively.