Presence Of Soil Research Articles

Environmental microplastic interact with heavy metal in polluted soil from mine site in the North of Tunisia: Effects on heavy metal accumulation, growth, photosynthetic activities, and biochemical responses of alfalfa plants (Medicago saliva L.)

As emerging persistent pollutants, microplastic (MPs) pollution attracted increasing attention worldwide since it is posing several environmental concerns. MPs interact with heavy metals in soil and may provoke damages on soil properties and ultimately impaired plants and human health. The present study aims to evaluate alfalfa plants (Medicago sativa) response after exposure to heavy metal polluted soils from mine site in the North of Tunisia in presence of environmental microplastic. For that, soils were sampled from two sites of Jebel Ressass mine in addition to a control soil. Plants were exposed to the three soils in presence of two increasing rates of microplastics D1 (1 mg/kg of soil) and D2 (100 mg/kg of soil) for 60 days. After harvest, agronomic parameters, chlorophyll content as well as heavy metal accumulation in plants were analyzed. Furthermore, oxidative status was evaluated in terms of malondialdehyde accumulation (MDA), catalase (CAT) activities and glutathion-S-transferase (GST). Overall, our finding highlights that MPs disrupted agronomic parameters and the photosynthetic activities of alfalfa plants. Additionally, our results revealed that the presence of MPs in polluted soils cause an increase on heavy metal accumulation in alfalfa shoots. Biochemical analyses demonstrated that the combined exposure to MPs and heavy metal induced oxidative stress in alfalfa plants by increasing CAT activity and MDA accumulation. The present investigation highlights the ecological risks of microplastics in terrestrial environment.

Metformin and lamotrigine sorption on a digestate amended soil in presence of trace metal contamination

The antidiabetic drug metformin and antiepileptic drug lamotrigine are contaminants of emerging concern that have been detected in biowaste-derived amendments and in the environment, and their fate must be carefully studied. This work aimed to evaluate their sorption behaviour on soil upon digestate application. Experiments were conducted on soil and digestate-amended soil as a function of time to study kinetic processes, and at equilibrium also regarding the influence of trace metals (Pb, Ni, Cr, Co, Cu, Zn) at ratio pharmaceutical/metal 1/1, 1/10, and 1/100. Pharmaceutical desorption experiments were also conducted to assess their potential mobility to groundwater. Results revealed that digestate amendment increased metformin and lamotrigine adsorbed amounts by 210% and 240%, respectively, increasing organic matter content. Metformin adsorption kinetics were best described by Langmuir model and those of lamotrigine by Elovich and intraparticle diffusion models. Trace metals did not significantly affect the adsorption of metformin in amended soil while significantly decreased that of lamotrigine by 12–39%, with exception for Cu2+ that increased both pharmaceuticals adsorbed amounts by 5 – 8%. This study highlighted the influence of digestate amendment on pharmaceutical adsorption and fate in soil, which must be considered in the circular economy scenario of waste-to-resource.

Estimation of seismic passive earth pressure coefficients for caissons in c-φ soils with a 3D log-spiral failure wedge

Passive resistance offered by soil to any embedded structure has been of significant interest to researchers since the inception of the concept. The present study deals with the estimation of passive earth pressure coefficients in seismic conditions that will control the passive resistance offered to a caisson embedded in c (cohesion) – φ (friction) soil in presence of surcharge loading. The three-dimensional (3D) geometry of failure wedge (log-spiral in vertical plane and oval in horizontal plane) has been obtained from the results of numerical analysis and past experimental studies. The critical failure surface has been obtained in the presence of all resisting components [unit weight (γ), cohesion (c) and surcharge (q)] by minimizing the passive resistance. Thereafter, seismic passive earth pressure coefficients for cohesion component (Kspc), surcharge component (Kspq) and unit weight component (Kspγ) have been obtained separately corresponding to the critical failure wedge obtained in the previous analysis. Limit equilibrium method of analysis in conjunction with pseudo-static approach has been used to perform the analyses. Charts for a variety of caisson geometry, soil and site condition and seismic condition have been prepared to facilitate prediction of passive resistance in a more economical and reliable manner since unique failure wedge has been considered for all the components instead of separate failure wedge which would be impractical.

Influence of Wetting-Drying Cycles on Strength Behaviour of Cured Lime Treated Soil Contaminated with Monovalent and Divalent Sulphatic Solutions

Exposure of lime treated expansive soil to sulphatic compounds are known to develop distresses due to the formation of ettringite or thaumasite, causing excess swell and alteration in strength behaviour. However, effect of wetting–drying (W-D) cycles caused due to seasonal variations on the behavior of lime treated soil exposed to sulphate contamination has not been addressed properly. Hence, present work investigates the impact of varying W-D cycles (0–4) on unconfined compressive strength (UCS) behaviour of lime treated soil in presence of two different sulphatic [i.e., monovalent sodium sulphate (Na2SO4) and divalent gypsum (CaSO4·2H2O)] contaminations. Lime treated soil samples are, firstly, cured for 7, 14 and 28 days and then used for further process of W-D cycles after completion of each curing periods. Varying sulphate concentrations (i.e., 3000, 10000, 16000, 20,000 and 30000 ppm) as prepared by using Na2SO4 and CaSO4·2H2O using distilled water have been used as contaminating solutions in W-D cycles process for lime treated soil. Strength behaviour of samples subjected to W-D cycles are determined at both wet and dry sides of each cycle. The results revealed that strength of lime treated soil is influenced highly by sulphatic concentration, types of sulphatic compound (monovalent or, divalent cations), curing periods as well as number of W-D cycles. Adverse impacts on strength are pronounced with an increase in sulphate concentration and number of W-D cycles. However, significant adverse effect on strength and durability are pronounced in the samples subjected to sulphate concentration more than 16000 ppm. Further, study is extended to elucidate the experimental results with physicochemical behaviour and microanalyses [XRD, FESEM, EDAX, FTIR and TGA-DTA]. It is confirmed that progression of number of W-D cycles with the increase in sulphatic concentration has influenced significantly to the microstructure of lime treated soil.

Hydro-mechanical behavior of two clayey soils in presence of household waste leachates

BACKGROUND AND OBJECTIVESIn landfills, containment is provided by natural or artificial clayey materials known for their low permeability and for their pollutant retention capacity. However, the properties of these media are modified by leachates, whose migration they are supposed to limit. This study aims to reconsider the criteria for choosing suitable materials to make a bottom liner through both their long term hydraulic and mechanical performances.METHODSTwo fine materials sampled in Burkina Faso (West Africa) have been characterized in order to compare their hydro-mechanical behavior in the presence of household waste leachates. The first material is classified as an inorganic clay of low to medium plasticity according to Casagrande plasticity diagram, it is mainly kaolinitic with some traces amounts of smectites. The second one is classified clayey sand of low to medium plasticity, the predominant mineral clay being kaolinite. Hydro-mechanical tests were performed on both sampled materials to judge the sealing properties of these materials, as well as the characteristics of deformation and rupture which have an important effect to ensure the durability of a bottom liner. All these tests were performed first with distilled water then with leachates as interstitial fluids in order to understand the modification of the hydro-mechanical properties of the clayey soils.FINDINGSLeachate contamination always alters hydraulic properties of the materials. However, between the two soils, the most clayey and the most impervious (soils from Nouna) undergo the deeper weathering. Indeed, hydraulic conductivity of these soils in contact with a synthetic leachate increases from 1.71x10-10 to 1.51x10-9 m/s. In contrast to soils from Boudry, these soils also undergo very significant settlements over the long term with compressibility indexes varying from 0.164 to 0.225. For both soils, the shear strength increases showing that, from this point view, the leachate work in the sense of of the bottom liner stability. For soils from Nouna, the effective cohesion increases from 3 to 21 kPa with a slight decrease of friction angle; for soils from Boudry a slight increase of cohesion is noticed while friction angle increases from 34 to 37°.CONCLUSIONThis comparative study is of practical use to environmental geotechnics professionals because it shows that the choice in designing a bottom liner must be a compromise between long term hydraulic and mechanical behaviors of soils. It is also important to know the nature of the flows to contain in order to ensure the durability of the structure.

Physical and Geotechnical Perspectives of Gypsum on Lime Stabilized Expansive Soil: A Critical Appraisal

The gypsum is the source of sulphate commonly found in the soils throughout the world. The expansive soils are considered as problematic soils as they exhibit uncertain swelling and shrinkage in presence of moisture. The expansive soils are treated with different stabilizers to suppress the swelling behaviour. Lime is most effective stabilizer used to stabilize the expansive soil. Researchers reported that expansive soil when treated with lime encounters the gypsum it regenerates the swelling. This regenerated expansion of lime treated soil in presence of sulphate may have alarming signs for sulphate bearing soils. The presence of sulphate alters the mineralogical behaviour of expansive clay. The stabilization additive used f or such soils needs more attention. A comprehensive approach towards proper understanding of the effects of gypsum on lime stabilized soil is required in order to understand the future threats of expansive soils. In this paper, an attempt has been made to present a comprehensive review on the effects of (Gypsum) calcium sulphate dihydrate on the physical properties of untreated and lime treated expansive soil have.

Leaching of Cd, Cu, Ni and Zn in a sewage sludge-amended soil in presence of geo- and nano-materials

In this study, the leaching of heavy metals; cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn); from soils amended with sewage sludge (SS) in the presence of nanoparticles (NPs) (ZnO and MgO) and zeolite was studied. After spiking of soil with heavy metals and mixing with SS and adsorbents, the samples were incubated for 7 days and the column leaching experiments (18 days) were done by two leaching solutions (CaCl2 and DTPA) in glass columns. Also, the leaching curves were simulated by the PHREEQC program. The lowest and highest amounts of Cd leached by CaCl2 were attributed to control soil and soil treated with Isfahan SS in the presence of MgO NPs, respectively, while the lowest amount of Cd leached by DTPA was obtained in soil treated with Rasht SS in the presence of ZnO NPs (7.1 mg kg−1 equivalent to 21.0% of total Cd in this treatment). The lowest amount of Cu leached by CaCl2 was related to the soil treated with Isfahan SS in the presence of ZnO NPs (1.3 mg kg−1). Also, the lowest leaching of Ni (1.4 mg kg−1) and Zn (0.4 mg kg−1) by CaCl2 was related to soil treated with Isfahan SS and Rasht SS in the presence of MgO NPs, respectively. The results showed that the addition of SS decreased Cd and Cu leaching but did not affect Ni and Zn leaching and the presence of NPs and zeolite reduced the leaching of heavy metals. The use of NPs (ZnO and MgO) and zeolite is also recommended as heavy metal adsorbents in contaminated soils. The modeling results showed that the simultaneous use of ion exchange and complex surfaces in the model caused good simulation of laboratory results. Overall, the PHREEQC program demonstrated an acceptable ability to simulate heavy metal leaching in contaminated soils treated with SS in the presence of various adsorbents.

Mechanistic elucidation of germination potential and growth of Sesbania sesban seedlings with Bacillus anthracis PM21 under heavy metals stress: An in vitro study

Soils contaminated with heavy metals such as Chromium (Cr) and Cadmium (Cd) severely impede plant growth. Several rhizospheric microorganisms support plant growth under heavy metal stress. In this study, Cr and Cd stress was applied to in vitro germinating seedlings of a Legume plant species, Sesbania sesban, and investigated the plant growth potential in presence and absence of Bacillus anthracis PM21 bacterial strain under heavy metal stress. The seedlings were exposed to different concentrations of Cr (25–75 mg/L) and Cd (100–200 mg/L) in Petri plates. Growth curve analysis of B. anthracis PM21 revealed its potential to adapt Cr and Cd stress. The bacteria supported plant growth by exhibiting ACC-deaminase activity (1.57–1.75 μM of α-ketobutyrate/h/mg protein), producing Indole-3-acetic acid (99–119 μM/mL) and exopolysaccharides (2.74–2.98 mg/mL), under heavy metal stress condition. Analysis of variance revealed significant differences in growth parameters between the seedlings with and without bacterial inoculation in metal stress condition. The combined Cr+Cd stress (75 + 200 mg/L) significantly reduced root length (70%), shoot length (24%), dry weight (54%) and fresh weight (57%) as compared to control. Conversely, B. anthracis PM21 inoculation to seedlings significantly increased (p ≤ 0.05) seed germination percentage (5%), root length (31%), shoot length (23%) and photosynthetic pigments (Chlorophyll a: 20%; Chlorophyll b: 16% and total chlorophyll: 18%), as compared to control seedlings without B. anthracis PM21 inoculation. The B. anthracis PM21 inoculation also enhanced activities of antioxidant enzymes, including superoxide dismutase (52%), peroxidase (66%), and catalase (21%), and decreased proline content (56%), electrolyte leakage (50%), and malondialdehyde concentration (46%) in seedlings. The B. anthracis PM21 inoculated seedlings of S. sesban exhibited significantly high (p ≤ 0.05) tissue deposition of Cr (17%) and Cd (16%) as compared to their control counterparts. Findings of the study suggested that B. anthracis PM21 endured metal stress through homeostasis of antioxidant activities, and positively impacted S. sesban growth and biomass. Further experiments in controlled conditions are necessary for investigating phytoremediation potential of S. sesban in metal-contaminated soils in presence of B. anthracis PM21 bacterial strain.

Lead Adsorption onto Clay Soil Treated with Sugarcane Organic Waste Biochar

This work aims to maximize the utilization of sugar cane cultivation and manufacture waste in Aswan Governorate, Egypt and turn it into biochar, which can be used to clean the environment from dangerous metals. Sugarcane organic wastes (filter cake, bagasse and sphere) biochars as waste bio-adsorbent materials were obtained using the pyrolysis at 350 and 700°C and 90 min residence time under limited oxygen conditions. Two batch trails were conducted to study the effects of biochar pH and shaking time on the adsorption of Pb ion from solution in precedence of soil and biochar. Models to study the kinetics of the adsorption process as pseudo-first-order and pseudo-second-order models were used.The results showed that the absorbed or precipitated (at high suspension pH) amount of Pb decreased in the order: soil treated with biochar bagasse pyrolysis at 350°C (BB350) > soil treated with biochar sphere pyrolysis at 350°C (SB350) > soil treated with biochar filter cake pyrolysis at 350°C (FB350) > soil only. At pH 9 maximum amounts of Pb of 1.794, 1.706 and 1.688 mg/g were adsorbed or precipitated on the soil treated with BB350, SB350 and FB350 respectively. However, Pb was maximum adsorbed or precipitated (1.33 mg/g) on the soil only at pH 8. The highest removal efficiency of Pb2+ from the solution was85% with treated the soil with SB350 while the lowest one was 55.5% occurred with the soil that was not treated with biochar at a shaking time of 80 minutes. The adsorption of Pb2+ by the soil in presence or absence biochars different fitted the pseudo second order kinetic model for all tested treatments (R2 ranged from 0.9901 for the soil treated with BB350 to 0.9994 for that treated with SB350).

Biofortification of green bean (Phaseolus vulgaris L.) and lettuce (Lactuca sativa L.) with iodine in a plant-calcareous sandy soil system irrigated with water containing KI

Uptake and translocation of iodine by green bean (Phaseolus vulgaris L.) and lettuce (Lactuca sativa L.) were investigated in a calcareous sandy soil-plant system. These plants were cultivated in calcareous sandy soil in presence of irrigation water with the iodine concentrations of 0.10, 0.25 and 0.50 mg/L. The growth of these plants was stimulated at the two lower iodine concentrations of 0.10 and 0.25 mg/L, but hampered at 0.50 mg/L. In lettuce the highest iodine dosage resulted in smaller leaf surface and higher number of leaves, nearly with the same biomass production. In the edible parts of green bean and lettuce plants irrigated with 0.25 mg/L iodine containing water, the iodine concentration levels amounted to 0.6 and 5.2 mg/kg dry weight (DW), respectively. In lettuce, the uptake and translocation of selected essential elements (P, Mg, Mn, Fe, Cu, Zn, B) were also stimulated (20-260%) by iodine treatment; however, in fresh bean pods this phenomenon was negligible. Considering the iodine level and moisture content of the fresh lettuce leaves and fresh bean pods, the consumption of 100 g fresh vegetable covers about 66%, 3% of the recommended dietary allowance (150 μg).

Fertilizer P Uptake Determined by Soil P Fractionation and Phosphatase Activity

The aim of this study was to determine if three cereal crops differed in their behavior to take up soil and fertilizer P, with emphasis on the relationship between phosphatase activity and P fractionation. We used a vertical rhizobox experiment with wheat, oat, and barley sown on Chilean Andisol (Barros Arana Series) with low P availability under greenhouse conditions. Plants were fertilized with the equivalent of 100 kg P ha−1 of triple superphosphate (TSP) or rock phosphate (RP). Plant biomass was determined for each of the three cereal plant species. Additionally, phosphatase (P-ase) activity in roots, soil in presence of roots (soil+R), and soil in absence of roots (soil−R) after 60-day growth were evaluated, and soil P fractionation was determined using the Hedley procedure. Fertilizer increased both P uptake and biomass production, particularly in shoots. The P uptake efficiency (∆P uptake between fertilized and unfertilized treatment/P input) was low (4.6%) and similar for both fertilizers for oat, but RP was more efficient for wheat (> 30%) and even more so for barley (nearly threefold), due the higher shoot P concentration of RP fertilized plants, which could be attributable to a major P-ase activity in plants fertilized with RP. Despite, fertilizer P was most clearly identified in labile inorganic soil fractions with Olsen P being greater after TSP addition than RP. In particular, plants showed contrasting soil+R P-ase activity inducing differences in soil+R P speciation, increasing labile NaHCO3-Pi and NaOH-Pi fractions with TSP. Strong relationships were found between the sum of labile Pi fractions and P uptake. We conclude that slower release of RP has a positive impact on P-ase activity and leads to better fertilizer efficiency than TSP, especially for barley.

K-Dynamics in a Continuously Submerged Limed and the Corresponding Unlimed Soil Subjected to One and Two Cycles of Drying Phase

A laboratory experiment was carried out to study the effect of drying phases on transformation of different fractions of K in submerged limed and the corresponding unlimed soil in presence and absence of N and K fertilizers. Changes in different fractions of K were monitored with time. Results showed that irrespective of treatments, available K increased in the limed soil throughout the period of incubation. However, non-exchangeable K showed an exactly opposite trend of results particularly in limed situation indicating a dynamic equilibrium between these forms of K in soils. Although, the trend of results of both available and non-exchangeable forms are totally different in unlimed situation. The decrease in 1N boiling HNO3 extractable K is comparatively more in limed soil subjected to single drying phase. No drastic variation in lattice and total K is observed under different treatment combinations. It indicates, maintenance of drying phase has little effect on lattice and total K in soils.

Surface displacements due to tunneling in granular soils in presence and absence of geosynthetic layer under footings

This paper presents the results of numerical modeling studies on the effect of displacements of tunneling in granular soils. Presence of building loads is considered, to find displacement generated at the surface on tunnel. Effect of varying eccentricities of building is simulated, to find influence of building on vertical and horizontal displacement. Studies were carried out in two cases of with and without a geosynthetic layer installed at the bottom of the footing. Results of analysis revealed, the presence of geosynthetic layer under footing, with building placed on centre line, reduced the surface displacements compared to displacement generated without geosynthetic layer. Presence of geosynthetic layer under footing had a dominant effect in reducing displacements in high storey structures. However, when the building was shifted to greater eccentricities from centre line, presence of geosynthetic layer, led to insignificant reduction of displacements on the centre line at the surface.

Rehabilitation of existing building structure in expansive soils: A case study in Laghouat, Algeria

This work presents results obtained from a case study conducted on M’kam neighborhood (600 housing social city) in Laghouat, Algeria. The bloc (J) in this location, suffering from damages that are attributed to the expansive clayey soil interaction with sewage disposal under foundations was the subject of rehabilitation in this study. The principal causes of observed structural damages were studied through diagnostic expertise (inspection-evaluation process) of the cracks and sewage disposal system of bloc (J). The results of this diagnostic investigation show that the main damages were mainly due to swelling of soil in presence of losses from sewage disposal. Remedial actions were suggested to revise and repair all the sewage disposal system and strengthen the foundations of the building to avoid further damages.

Alfalfa crops amended with MSW compost can compensate the effect of salty water irrigation depending on the soil texture

Abstract The availability of water resources of marginal quality such as drainage water or high-salt containing groundwater is turning into an important issue in Tunisia and other countries with scarce water resources. A pot experiment was carried out to evaluate plant production, nutrient content and heavy metal bioaccumulation in agricultural soils amended with MSW compost and irrigated with salty water, by using two different soil textures (clay and sandy). Salt water supply decreased plant dry yield in both soils. Salt stress had significantly reduction in plant biomass in sandy soil compared to those in clay soil (biomass of dry weight is significantly higher in clay soil than those in sandy soil in presence of salt: percentage of growth compared to control was 55% for clay soil and 45% for sandy soil). The application of Municipal Solid Wastes (MSW) Compost increased significantly alfalfa productivity in both soils (Dry weight is significantly higher in presence of compost: 140% for clay soil and 125% for sandy soil). In non-amended soil, the growth was reduced significantly by salt stress (50% in clay soil, 26% in sandy compared to the soils without salty water application). Plants irrigated with salty water accumulated much more sodium on sandy soil (1.74 mmol g−1) than on clay one (0.87 mmol g−1 DW). Compost did not reduce sodium accumulation in aerial parts on sandy soil, whereas it slightly reduced it in those grown on clay soil. Zinc (Zn), Copper (Cu), Lead (Pb) and Cadmium (Cd) concentrations showed the same trend for both soil types. They increased statistically significant by salinity to 124–189%, the highest rise was found in Cu concentration on clay soil. The order of metal uptake was: Zn > Cu > Pb > Cd. A higher significant shoot accumulation of heavy metals (up to 305% of the control) was noticed in the presence of compost with no difference between salt-treated and non-treated. MSW compost amendment caused an increase of the studied heavy metals in alfalfa shoots grown that was higher on sandy soils than clay soils. Heavy metals in plants remained lower than phytotoxic level and these level of accumulation did not restrain the enhancement of alfalfa yield. MSW compost at 40 t ha−1 was convinent to do not attend phytotoxic level. These results suggest that MSW compost compensates, at least partially, the negative effect of salinity on plant growth and nutrient uptake and that it is important to know soil texture to apply compost to remediate salty degraded soils.

Rehabilitation of existing building structure in expansive soils: A case study in Laghouat, Algeria

This work presents results obtained from a case study conducted on M’kam neighborhood (600 housing social city) in Laghouat, Algeria. The bloc (J) in this location, suffering from damages that are attributed to the expansive clayey soil interaction with sewage disposal under foundations was the subject of rehabilitation in this study.The principal causes of observed structural damages were studied through diagnostic expertise (inspection-evaluation process) of the cracks and sewage disposal system of bloc (J). The results of this diagnostic investigation show that the main damages were mainly due to swelling of soil in presence of losses from sewage disposal. Remedial actions were suggested to revise and repair all the sewage disposal system and strengthen the foundations of the building to avoid further damages.

The Effect of Olivine Content and Curing Time on the Strength of Treated Soil in Presence of Potassium Hydroxide

When olivine (Mg2SiO4) is activated with potassium hydroxide (KOH), it acquires the ability to improve the unconfined compressive strength of soil. This paper investigates the use of olivine for soil stabilisation through alkaline activation by focusing on the role of different alkali activated olivine contents (5–20 wt%) in stabilising native soil at different curing durations. The strength results were supported by a detailed microstructural and compositional analysis including scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Use of olivine in the presence of KOH increased the shear strength of soil up to 7.4 MPa in 90 days as a result of the formation of brucite, quartz and mullite in the structure of treated soil. This achievement implies a tremendous effect of olivine on the strength behaviour of treated soil. These results provide essential information which is significant from an environmental perspective as it offers a low energy alternative to existing technologies, for soil stabilisation.

Stability of Supported Vertical Cuts in Granular Matters in Presence of the Seepage Flow by a Semi-Analytical Approach

Vertical cuts are prone to several types of failure, such as piping, ground heaving and deep seated or base failure. The latter is the subject of this study and probably attracts less attention in comparison with other types of failure. Although it is commonly believed that such a failure is rare in normal conditions; in presence of the seepage flow, deep seated failure is much likely to initiate and advance prior to other types of failure. In this paper, the stability analysis of vertical cuts in granular soils in presence of the seepage flow is studied against the deep failure. To do so, the stability analysis is made by the use of the well-known method of stress characteristics with inclusion of the seepage flow force. This nonuniform flow field renders the stability analysis quite complex. A semi analytical approach, based on complex algebra, is presented to find the flow filed which is accurate and much faster for calculation of the seepage force at arbitrary points in the field. The solution of the flow field is a background solution for the stress field which is to be found to assess the stability.

Transformation of different fractions of K in a limed and the corresponding unlimed soil in presence and absence of N and K fertilizers

Transformation of different fractions of K in a limed and the corresponding unlimed soil in presence and absence of N and K fertilizers

Phenanthrene Sorption onto Kaolinite; Heavy Metals and Organic Matter Effects

Several factors effect on sorption of polycyclic aromatic hydrocarbons (PAHs) in soil. Co-existence of metals and organic matter of soil are among important affecting factors on sorptive behavior of PAHs. This research investigated the effect of organic matter content and heavy metals (lead, nickel and zinc), on sorption of phenanthrene onto kaolinite. For this purpose, sorption of the organic matter to the kaolinite clay was investigated through batch experiments. Six types of soils in presence and absence of metals at different levels organic matter were prepared for assessment of phenanthrene sorption. Obtained data for phenanthrene sorption were well described by linear Freundlich isotherm. Making comparison between linear distribution coefficients (Kd) of phenanthrene for six prepared soils showed that heavy metals and organic matter can increase the sorption of phenanthrene. Heavy metals coexisting with organic matter have a synergic effect onphenanthrene Kd increment. A model to predict the sorption of phenanthrene onto kaolinite was developed and verified using obtained experimental data.