High Cation Exchange Capacity Research Articles

Spatial variation in iodine content with relation to soil physicochemical properties in lower Himalayan region

Topography of a place has a significant impact on soil characteristics that ultimately influence soil iodine levels. Lower Himalayan region (LHR) in Pakistan has a wide range of climatic and geological variations. Hence, an investigation was conducted to analyze the iodine concentration and other physicochemical properties of soils in two LHR districts, Haripur and Mansehra. Spatial analysis indicated a decrease in iodine levels in the mountainous regions in comparison to the flat portions of LHR. Soil samples obtained from different locations across Haripur had a stronger affinity for iodine due to variations in solubility and adsorption of iodine to soil clay components, which can be attributed to lower pH, higher organic matter, and a higher cation exchange capacity (CEC). In contrast to the plains of Haripur, elevated locations in the Mansehra district had decreased levels of iodine, along with a higher soil pH and reduced soil organic matter. The soil erosion and depletion of soil micronutrients in the hilly region of Mansehra may be attributed to the unfavorable soil conditions and excessive precipitation. Presence of clay, iron (Fe), and aluminum (Al) in the soil led to a rise in iodine levels. Iodine concentrations exhibited an inverse relationship with soil acidity. Study revealed a direct correlation between soil iodine levels and their cation exchange capacity (CEC) and clay content. This study aims to gather fundamental data for the chosen regions of LHR to address illnesses caused by iodine deficiency.

Mapping of volcanic soil chemical properties with digital soil mapping after the prolonged eruption of Mt. Sinabung (2013-2020)

Volcanic soils in Indonesia cover an area of about 5.4 million ha and around 2.7 million ha in Sumatra. The prolonged eruptions of Mt. Sinabung in North Sumatra from 2013 to today eject pyroclastic materials, which blanketed and altered the soil surface. As a result, volcanic soil formed from these pyroclastic deposits. This study aims to map the chemical properties of volcanic soils after the prolonged eruption of Mt. Sinabung from 2013-2020. Thirty-four soil samples were collected at a depth of 0-20 cm according to the grid sampling system with an interval of 1x1 km covering an area of about 4,500 ha. Regression kriging (RK) was applied to predict the soil’s chemical properties and distribution spatially. The soil samples were air dried, sieved, and analyzed to determine soil pH (H2O and KCl), available, potential and retention P, organic carbon, total nitrogen, cation exchange capacity (CEC), and exchangeable basic cations. Soil pH (H2O) ranges from very acidic to neutral (4.14-6.52) and very acidic to acidic pH (KCl) (3.89-5.26), low to very high available-P (3.46-382.01 ppm), potential-P very low to very high (3.76-230.26 mg 100g-1), P-retention is categorized as very high (90-99%). The organic Carbon range from low to very high (1.73-13.05%), low to high total nitrogen (0.13-0.60%), low to high cation exchange capacity (11.78-97.71 cmolc kg-1), and exchangeable base cations are categorized as high with K values (1.60-2.98 cmolc kg-1). Na (3.72-7.45 cmolc kg-1) and Mg (5.79-12.15 cmolc kg-1) were categorized as high and Ca very low (0.039-0.157 cmolc kg-1). The estimated area of soils with pH between 4 and 5 is about 424.85 ha, and soils with pH between 5 and 6 covered an area of approximately 3,964.81 ha. Our findings suggest that persistent eruptions of Mt. Sinabung supply new plant nutrition, which can enrich and increase soil fertility in the future.

Tunable Colloidal Properties of Lauramidopropyl Betaine and Li Co-modified Montmorillonite in Ethanol/Water.

Montmorillonite (Mt) is a hydrophilic clay mineral with a generally high cationic exchange capacity and a remarkable swellability in water. Yet the application of Mt in cosmetics, paints, polymer nanocomposites, drug delivery systems, and tissue engineering are limited due to its unfavorable swelling and dispersion in alcohol/water mixtures. Improving the swellability and dispersibility of Mt in mixtures of ethanol and water remains challenging. Here, we showed that the swellability and dispersibility of Mt in ethanol/water could be significantly enhanced when lithium-Mt (Li-Mt) was intercalated by zwitterionic surfactant lauramidopropyl betaine (LPB). The binding mechanism of the LPB intercalate to Li-Mt originated from a combination of van der Waals forces, ion-dipole interaction, and electrostatic attraction. Due to the synergistic effect of Li+ and LPB, the comodified Mt (LPB-Li-Mt) exhibited excellent swellability, dispersibility, and rheological properties. The structure, morphology, zeta potential, dispersibility, and gel-forming performance of LPB-Li-Mt can be modulated by the concentrations of ethanol in ethanol/water mixtures. When the ethanol concentration increased to 75% v/v ethanol solution, the free swelling of LPB-Li-Mt remained above 80%. The results from X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray photoemission spectrometry, and small-angle X-ray scattering confirmed the full exfoliation of LPB-Li-Mt at 75% (v/v) ethanol solution. The formation of a stable colloidal LPB-Li-Mt dispersion in a mixture of ethanol/water might be derived from the association between water molecules and the Li+, the hydrophobic interaction, and the ion-dipole of ethanol with the LPB molecules. The findings provide a guide for improving dispersion and swelling of Mt and modified ones in water-miscible organic solvents.

Variation of Geochemical Properties of Soils in Tropical Lowland Rainforests in Sri Lanka

Tropical lowland rainforests (TLRFs) of Sri Lanka are considered as diverse ecosystems which play a vital role in climate change mitigation. In recent years, increasing deforestation leads to diminishing their potential ecosystem roles. For efficient forest conservation, knowledge of both above- and below-ground characteristics of TLRFs is required. Currently, above-ground information on TLRFs is sufficiently available but the details on the below-ground characteristics are limited. Therefore, this study was carried out to investigate pedo-geochemical properties of lowland rain forests of Kanneliya (KDN) and Pitadeniya, (PTD) in Sri Lanka. Four sampling plots with 1 ha in size (KDN1, KDN2, PTD1 and PTD2) were established, selecting altitudes of 117, 174, 509, and 618 m asl, respectively. Five representative near-surface (up to 25 cm) samples were collected from each plot for the investigation. Soil pH, electrical conductivity (EC), and cation exchange capacity (CEC) were measured while soil organic matter (SOM) content was determined by (i) Walkey-Black (WB) and (ii) Loss on ignition (LI) methods. Data were analysed by ANOVA and means were compared using Duncan‘s test. All measured parameters were significantly different (P<0.05) among the sampling plots. Soil pH and EC values were ranged between 3.43– 3.78 and 0.28–0.44 dS m-1, respectively. The highest CEC was recorded in PTD2 (11.09±3.44 cmol(+)/kg) whereas the lowest was in PTD1 (5.31±1.26 cmol(+)/kg). The highest SOM was recorded in PTD1 (17.71±4.42% in WB, 18.04±3.98% in LI) whereas the lowest was noted in PTD2 (5.81±3.07% in WB, 8.21±2.13% in LI). According to the comparison made between WB and LI methods, LI method recorded higher SOM content. The actual SOM and volatilizable water in hygroscopic mineral fractions might be the reason for the higher values in LI method. All acquired data were compared with standard interpretation data and accordingly, soils of the measured TLRFs are acidic, non-saline and non-reduced with sufficient soil aeration. Even though, TLRF vegetation produce high amount of biomass, soil CEC and SOM contents are low in the study area due to rapid microbial decomposition and absorption of dense vegetation. There was no linear relationship between measured parameters and altitude. Overall, measured soil chemical properties can be considered as ideal indicators of TLRFs conservation and therefore, it needs to be correlated with above-ground properties for understanding the behaviour of TLRFs responding to conservation strategies. 
 Keywords: Forest conservation, Soil chemical properties, Soil organic matter content, Tropical lowland rainforest

Organic Amendments to Short Rotation Coppice (SRC) Plantation Affect Species Richness and Metal Accumulation of Spontaneously Growing Herbaceous Plants

Excess potentially toxic metals (PTMs) in soils require ad hoc approaches to salvage. Hence, this study explored the shoot accumulation of cadmium (Cd), lead (Pb), and zinc (Zn) by herbaceous plants growing under previously established Salix and Populus clones Short Rotation Coppice (SRC) with compost and sewage sludge applications in an abandoned metallurgical site, Podlesí, Czech Republic; PTM decontamination of soils. Soils within the SRC experimental site and outside considered as control were analyzed for their chemical properties by multi-analytical techniques. Shoots of spontaneously growing herbaceous plants under trees in the site and without trees in control were determined for pseudo-total Cd, Pb, and Zn contents. Moderately to slightly acid soils, high cation exchange capacity, and C/N ratio supported mineralization and relative mobility of total Cd (7.7–9.76), Pb (1541–1929), and Zn (245–320 mg kg−1) in soils. Although soil amendments improved chemical properties, compost application supported higher species richness than sewage sludge. Over 95% of plants accumulated Cd and Zn above the WHO threshold and green fodder in the Czech Republic, with 36% Pb above the regional limit (40 mg kg−1). Approximately 100, 50, and 6% of herbaceous species had Cd, Pb, and Zn accumulation, respectively, higher than published average upper limits in plants (0.2 Cd, 10 Pb, and 150 Zn mg kg−1). Dicots recorded higher Cd content, Tenacetum vulgare (L.), Hypericum maculatum (Crantz), and Cirsium arvense (L.); Stachys palustris (L.), Lamium perpereum (L.), and Campanula patula (L.) for Pb; Glechoma hederaceae (L.), C. patula, and C. arvense for Zn in all treatments. Appropriate soil amelioration of SRC-supported PTM mobility and excess herbaceous species shoot accumulation, growth, and richness.

Synthesis and evaluation of aromatic stationary phases based on linear solvation energy relationship model for expanded application in supercritical fluid chromatography

In the last decade, the separation application based on aromatic stationary phases has been demonstrated in supercritical fluid chromatography (SFC). In this paper, four aromatic stationary phases involving aniline (S-aniline), 1-aminonaphthalene (S-1-ami-naph), 1-aminoanthracene (S-1-ami-anth) and 1-aminopyrene (S-1-ami-py) were synthesized based on full porous particles (FPP) silica, which were not end-capped for providing extra electrostatic interaction. Retention mechanism of these phases in SFC was investigated using a linear solvation energy relationship (LSER) model. The aromatic stationary phases with five positive parameters (a, b, s, e and d+) can provide hydrogen bonding, π-π, dipole-dipole and cation exchange interactions, which belong to the moderate polar phases. The LSER results obtained using routine test solutes demonstrated that the aforementioned interactions of four aromatic stationary phases were influenced by the type and bonding density of the ligand, but to a certain extent. Furthermore, the LSER data verified that the S-1-ami-anth column based on full porous particles silica had higher cation exchange capacity (d+ value), compared to the commercialized 1-AA column (based on the ethylene-bridged hybrid particles). The relationship between the d+ value and SFC additive was quantitatively proved so as to regulate electrostatic interaction reasonably. This value was greatly increased by phosphoric acid, slightly increased by trifluoroacetic acid and formic acid, but significantly reduced by ammonium formate and diethylamine. Taking the S-1-ami-naph column as an example, better peek shape of the flavonoids was obtained after the addition of 0.1 % phosphoric acid in MeOH while isoquinoline alkaloids were eluted successfully within 11 min after adding 0.1 % diethylamine in MeOH. Combined with the unique π-π interaction and controllable electrostatic interaction, the aromatic stationary phases in this study have been proven to have expandable application potential in SFC separation.

KARAKTERISASI INDIKATOR KESESUAIAN LAHAN KOMODITI NANAS LOKAL (Ananas comosus) KABUPATEN MAJENE

Indonesia boasts a high biodiversity, intricately linked to the various ecosystems within its territories. In Majene Regency, West Sulawesi Province, for instance, there is a unique commodity in the form of pineapple, locally known as 'pondang'. One of the efforts to preserve this unique pineapple commodity is to understand the characteristics of the cultivation land that has sustained it over time. This research aimed to characterize the land in the cultivation areas of Majene's local pineapple as fundamental information for farmers to comprehend the plant growth ecosystem and manage the land optimally. The research utilized purposive random sampling based on the cultivation locations of Majene's local pineapple. Observations revealed that the cultivation land conditions for Majene's local pineapple had an average temperature ranging from 25.65 to 29.75 ºC, rainfall between 1,488.05 and 2,820.50 mm, with humidity ranging from 63.38 to 89.00%. Additionally, soil fertility conditions in the research locations indicated high nutrient retention, as shown by slightly acidic to neutral soil pH values and high Cation Exchange Capacity (CEC), although some available nutrients indicated very low to low soil fertility levels, such as potassium. Soil management significantly influenced nutrient availability, soil salinity, and alkalinity in the research locations.

Exploring time-dependent seawater desalination capacity of terracotta clay soil and coconut shell charcoal

A study assessed the effectiveness of two locally available materials, terracotta clay soil, and coconut shell charcoal, as desalination membranes. The research also explored the impact of exposure time on the desalination process. The study employed a 3 × 3 factorial experiment using a Randomized Complete Block Design (RCBD) with three replications. It compared three different desalination membranes: pure clay, pure charcoal, and a combination of clay and charcoal in a 2:3 ratio. Additionally, three exposure times of seawater to the membranes were examined: 4 h, 8 h, and 12 h. The findings revealed that the different desalination membranes significantly affected (p < 0.05) the salinity level and the treated seawater's sodium and chloride ions content. Notably, clay soil demonstrated higher effectiveness in desalinating water than charcoal and the combination of clay and charcoal. However, the exposure time to the membranes did not significantly affect any of the parameters studied. Based on these results, it is evident that clay soil possesses the potential to serve as a desalination membrane, attributed to its higher Cation Exchange Capacity (CEC) and efficiency in reducing salinity. Future research could investigate ways to improve the efficiency of this material, study the effects of various parameters on the desalination process, and explore scaling up the desalination process for large-scale water production. Overall, this study contributes to developing cost-effective and sustainable methods for providing clean water to areas facing limited access to fresh water.

Pengaruh Pemberian Biochar Terhadap Perubahan Sifat Kimia Tanah Vertisol dan Pertumbuhan Kacang Hijau (Vigna radiata L.)

Vertisols are soils that have a high cation exchange capacity but tend to have a low organic matter content. Meanwhile, nutrients availability in vertisol tends to be low because these elements are bound by clay particles, so the nutrient availability is limited for plantsThe aim of this research is to investigate the influence of rice husk biochar and corn cob biochar application on the changes in chemical properties of Vertisol soil and the vegetative growth of mung bean (Vigna radiata L.). The study was conducted using a Randomized Complete Block Design (RCBD) with an experimental approach. There were 8 treatments repeated 6 times, resulting in a total of 48 experimental units. The rice husk biochar (P) treatments included the control without rice husk biochar (BSP0), rice husk biochar at a rate of 60 g/kg soil (150 tons/ha) + 2.5 kg soil (BSP1), rice husk biochar at a rate of 30 g/kg soil (75 tons/ha) + 2.5 kg soil (BSP2), and rice husk biochar at a rate of 15 g/kg soil (37.5 tons/ha) + 2.5 kg soil (BSP3). The corn cob biochar (J) treatments included the control without corn cob biochar (BTJ0), corn cob biochar at a rate of 60 g/kg soil (150 tons/ha) + 2.5 kg soil (BTJ1), corn cob biochar at a rate of 30 g/kg soil (75 tons/ha) + 2.5 kg soil (BTJ2), and corn cob biochar at a rate of 15 g/kg soil (37.5 tons/ha) + 2.5 kg soil (BTJ3). The research data were analyzed using Analysis of Variance (ANOVA) at a significance level of 5%. Significant differences between treatments were further analyzed using the Duncan's New Multiple Range Test (BNJ) at a significance level of 5%. The soil analysis was carried out at the Soil Physics and Soil Chemistry Laboratories, Faculty of Agriculture, Universitas Mataram. The results of the research showed that biochar application influenced the chemical properties of the soil (pH, Cation Exchange Capacity, Organic-C) and the growth of mung bean plants in Lombok's Vertisol soil. Biochar did not have a significant effect on the height of mung bean plants at 7 and 14 days after planting (DAP), but it had a significant effect at 21, 28, and 35 DAP. However, the application of biochar did not significantly affect the number of leaves and dry weight of mung bean plants.

Additional of Organic Amendments in the Soil to Increase the Various Crop Yield: A Review

Agricultural production is threatened by the scarcity of current natural resources, an increasing total population, climatic change, and degraded soils. To feed the world's growing population, development strategies must be implemented that sustainably increase agricultural production while at the same time reducing the negative impacts of the activities. A number of amendments are currently being researched to improve the structure and fertility of soils. The properties of organic materials (biochar (BC), husk, and compost) were examined. The properties of BC have a large specific surface area, are highly porous, and have a high cation exchange capacity (CEC). These amendments could be used to slow down the continuous soil degradation and maintain soil productivity while facing global challenges. While the environmental effects have been extensively studied, the extent to which they can contribute to long-term intensification has yet to be determined. This review aims to contribute to the topic by providing a concise summary that combines both environmental evidence and agronomic considerations.

Induced Polarization Images the Plumbing System of Hydrothermal Vents in an Intracontinental Rift, Lake Abhé, Republic of Djibouti

AbstractRecent developments in induced polarization allow for the characterization of alteration halos within hydrothermal systems. We explore the possibility of using electrical conductivity and normalized chargeability tomograms in concert to image hydrothermal conduits thanks to their high cation exchange capacities associated with alteration. The hydrothermal plumbing system of the late‐stage rift area of Lake Abhé (Republic of Djibouti) is used to test the ability of induced polarization to reveal such plumbing system associated with the prominent hydrothermal chimneys serving as vents for the hydrothermal fluids. We show that induced polarization can be used to provide an alteration tomogram, which highlights the flow path toward 2 chimneys in the top 70 m below the surface of the sediments at Lake Abhé.

Comparison of The Antibacterial Activity of Bentonite and Amoksisilin Against Streptococcus Mutans Causes of Caries

Streptococcus mutans is a normal flora bacteria in the oral cavity. Streptococcus mutans colonizes the oral cavity during the eruption of the first teeth, which in turn causes the teeth to experience caries. Bentonite is a clay consisting of the mineral smectite, especially montmorillonite. Montmorillonite is a member of smectite with the chemical formula (Al2O3 4 SiO2 x H2O). The high cation exchange capacity and fine particle size can inhibit bacterial growth. This study aims to compare the antibacterial activity of bentonite and amoksisilin against Streptococcus mutans. Materials and research methods divide the bentonite solution into five groups with concentrations of 5%, 10%, 20%, 40%, and 100%, and one group of amoksisilin and one control group. The solution was tested for antibacterial activity by diffusion on blood agar against Streptococcus mutans. The results showed that all bentonite solution groups differed from the amoksisilin group (p 0.05). Meanwhile, the antibacterial activity of the bentonite solution group was no different from the negative control group (p 0.05). The conclusion from this study was that there was a difference in antibacterial activity between the bentonite and amoksisilin groups, where bentonite did not show inhibition of the growth of Streptococcus mutans bacteria

Basic Study on Applicability to Artificial Barriers for Radioactive Waste Disposal Facility for Various Zeolites

Artificial barriers are being considered for the burial disposal of low-level radioactive waste in Japan. The artificial barrier consists of i) a low permeable layer made of bentonite materials that suppresses migration of nuclides due to advection, and ii) a low diffusion layer that uses cementitious materials that suppresses migration of nuclides due to diffusion. In addition, as methods of disposing of radioactive waste generated by the accident at the Fukushima Daiichi Nuclear Power Station, controlled disposal and isolation-type disposal are being considered. We thought that it would be effective to add adsorption performance to the performance of suppressing migration of such radioactive substances. In this study, we designed and experimented on the adsorption performance of mortar mixed with various zeolites, which had never been examined. As evaluation methods, i) fluidity, ii) strength, iii) low diffusivity, and iv) distribution coefficient of cesium and iodine were obtained. Based on the results, we reexamined the composition and conducted experiments to examine the applicability to high-adsorption artificial barriers. As a result, it was confirmed that the mass transfer resistance tends to be low due to the zeolite being porous. It was also shown that the strength of mortar mixed with zeolite depends on the cement matrix. As a result of this research, the distribution coefficient of cesium in cementitious materials using zeolite with a high cation exchange capacity designed in this research is higher than that of cementitious materials for low-level radioactive waste disposal facilities currently in operation 1,500 times was obtained. On the other hand, we were able to discover the possibility of examining construction on a full-scale regarding fluidity and compressive strength. As a future task, it was found that it is necessary to investigate a more practical artificial barrier by increasing the strength and densification of the cement paste.

Organic Matter Matters—The Imaginary Conductivity of Sediments Rich in Solid Organic Carbon

AbstractSolid organic matter (OM) is a biogeochemically relevant constituent of soils and sediments. It also affects sediments' geophysical properties, but is often overlooked in hydro‐ and biogeophysical approaches for the characterization of the shallow subsurface. Here, we explore the potential of spectral induced polarization (SIP) to delineate OM‐rich zones in the subsurface and provide insights into the mechanisms that drive OM‐polarization using measurements on both field cores and artificial OM‐sand mixtures. Both, field samples and artificial mixtures showed a linear relationship between the total organic carbon (TOC) content and charge storage (imaginary conductivity). The high cation exchange capacity of OM drives the increase in polarization and can help in delineating potentially microbially active OM‐rich zones in cores or field surveys. To avoid misinterpretation of SIP data in unconsolidated media, we strongly suggest quantifying TOC content in sediment samples to accompany the interpretation of field surveys.

Application of olive mill waste-based biochar for improving wheat response to salt stress

The production of olive mill solid waste (OMSW) raises concerns due to its toxicity and negative environmental impact. However, by utilizing pyrolysis, OMSW can be converted into biochar, a carbon-rich material that detoxifies the waste and preserves its nutrient content. The OMSW-based biochar possesses alkaline properties (pH 9.6), low electrical conductivity (EC), high cation exchange capacity (CEC), a porous surface morphology, various surface functional groups, and high mineral content. This study assessed the influence of two concentrations (5% and 10%) of OMSW-based biochar on wheat plants' growth biomarkers and physiological characteristics subjected to salt stress conditions (150 mM NaCl). Findings of the study revealed that salt stress had deleterious effects on various parameters, including shoot height, fresh and dry weights of shoots and roots, relative water content (RWC%), membrane stability index (MSI%), photosynthetic pigments, and photosynthetic parameters such as the coefficient of the effective quantum yield of photochemical energy conversion of PSII (ØPSII), photochemical quenching (qP), and photochemical efficiency of PSII (Fo, Fm, Fv/Fo, and Fv/Fm). Furthermore, the levels of lipid peroxidation (MDA), hydrogen peroxide (H2O2), superoxide dismutase (SOD), and peroxidase (POD) activities significantly increased in stressed plants. On the other hand, applying both concentrations of OMSW-based biochar effectively improved the overall performance of wheat plants, irrespective of the presence of salinity. OMSW-based biochar is a promising strategy for promoting wheat growth in salt-stressed soil by improving various growth parameters and mitigating plant oxidative stress.

Physico-chemical Characterization of Biochar from Different Biomass Materials

Aim: To conduct the physico-chemical analysis of biochar derived from various organic residues, an examination of the physical characteristics including bulk density, water retention capacity, and the chemical properties such as pH, electrical conductivity, cation exchange capacity, total organic carbon, as well as the concentration of macro and micro nutrients were evaluated.&#x0D; Study Design: Experiment was conducted in completely randomized design with 7 treatments and 3 replications.&#x0D; Place and Duration of Study: The investigation was conducted at Integrated Farming System Research, Karamana, Kerala Agricultural University during 2021-2023.&#x0D; Methods: Organic residues from different sources were converted into biochar utilizing a double barrel Biochar Kiln, and subsequently, the biochars were analyzed in a Soil and Plant Analysis laboratory to determine their physical and chemical properties.&#x0D; Result: Physio-chemical properties of biochar vary significantly with the choice of feedstock material. Banana pseudostem biochar reported the lowest bulk density (0.21 Mg m-3) and highest water holding capacity (327.74%). All the biochar produced were alkaline in nature, and they contained high cation exchange capacity ranging between 9.34 to 14.10cmol (+) kg-1. Macro and micro nutrient contents were comparatively higher in Limnocharis flava biochar and Banana pseudostem biochar.&#x0D; Conclusion: Organic residues can be successfully converted to biochar and results obtained show the suitability of application of produced biochar as a soil amendment.

Desorption kinetic and sequential extraction of Pb and Zn in a contaminated soil amended with phosphate, lime, biochar, and biosolids.

The mining and metallurgical industry sector activities often release potential toxic elements (PTE) surrounding exploitation area. We evaluated the addition of phosphate and lime using the dosage of 0.5:1, 1:1, and 2:1 molar ratio of PO43- and CO32- to the sum of PTE, respectively, and also, biochar and biosolids using the dosage of 2.5, 5, and 10% (m:m) to immobilize PTE in contaminated forest soil (Pb (270mgkg-1) and Zn (858mgkg-1)) near an abandoned mine site in Brazil. The desorption by stirred flow kinetics revealed that 15% of the total Zn and 12% Pb contents are mobile before any amendment application. Phosphate amendment decreased Pb desorption but increased Zn desorption. Biochar and biosolids immobilize high amounts of Zn and Pb because of their high cation exchange capacities and alkaline properties; however, 20% biosolid dose increased Pb desorption. X-ray absorption spectroscopy suggested Zn-kerolite as the major species in the contaminated soil, likely from mine dust. The change in Zn speciation after soil amendment addition indicated that biochar and lime kept a high proportion of Zn-Al species, whereas phosphate and biosolids led to more Zn-Fe species. Our results pointed out that lime might reduce both Pb and Zn mobilities; however, field trials are crucial to confirm the immobilization efficiency of lime and other amendments over long term.

Adsorption of uranium(VI) by natural vermiculite: Isotherms, kinetic, thermodynamic and mechanism studies

Human activities such as mining uranium resources, hydrometallurgy, and nuclear fuel preparation inevitably produce wastewater sludge containing radionuclides, posing a severe threat to the environment around the production site. Natural clay minerals have been widely used in groundwater pollution remediation because of their high cation exchange capacity. Through static batch experiments, the optimal pH range of vermiculite for U(VI) adsorption was 6–8,the maximum adsorption capacity was 1.62 × 10−5 mol g−1. The kinetic adsorption results indicated that the adsorption mode was mainly multilayer non-homogeneous chemisorption. In addition, the adsorption of vermiculite on U(VI) was found to be a heat absorption process according to the thermodynamic model fitting, and the spontaneous reactivity of U(VI) adsorption on vermiculite surface was positively correlated with temperature and negatively correlated with the initial concentration of U(VI). Combined with SEM-EDS and FT-IR results, the adsorption process of vermiculite on U(VI) is mainly an ion exchange and complexation reaction, and U(VI) is removed in the form of ≡ SUOU22+ or ≡ SOUO2OH, etc., by XPS means. The results of this study not only investigated the adsorption behavior and mechanism of natural vermiculite in groundwater contaminated with simulated uranium but also provided theoretical support for its feasibility in remediating uranium-polluted groundwater.

Induced polarization of volcanic rocks. Part 7. Kimberlites

SUMMARY In the field, kimberlites are characterized by high electrical conductivities (about 0.1 S m−1) compared to most igneous rocks. The reason for these high conductivities has not been fully elucidated to date. We investigate here the spectral induced polarization of seven core samples of kimberlites in the frequency range 1.43 mHz–20 kHz. The measurements are made at pore water conductivities ranging from 0.07 to 2.4 S m−1 (NaCl, 25 °C). We also measured the cation exchange capacity (CEC), the specific surface area (SSA) and the magnetic susceptibility of the core samples. We characterized the samples by optical microscopy as well as the X-ray diffraction and thermogravimetric analyses. Based on the electrical measurements, we obtained values of the surface conductivity produced by the double electrical layer coating the solid particles, and the normalized chargeability values characterizing the polarization magnitude of these materials. Mineralogical analyses show significant amount of magnetite (from 2 to 9 wt. per cent, approximately 1 to 4 per cent in vol. content) and smectite (from 1 to 44 wt. per cent) in the core samples. The main contributor of the CEC is smectite because of its very high CEC. The quadrature conductivity, the normalized chargeability, and the surface conductivity are controlled by the CEC normalized by the tortuosity of the pore space (product of the formation factor by the porosity). Our data demonstrate that the conduction and polarization of kimberlites are both controlled by the presence of smectite rather than associated with magnetite. Comparing the new data set and data recently obtained with volcanic rocks from both shield and strato-volcanoes in the previous papers of this series, we show that the model of polarization of the dynamic Stern layer correctly describes the complex electrical conductivity of kimberlites as well. Our results also explain the cause of electrical conductivity anomalies detected at kimberlite pipes and offer new perspectives in using induced polarization method for the exploration of kimberlites around the world.

Models of Pb distribution and uptake in inundated paddy and maize cropping systems

&lt;p&gt;High-traffic highway crossing agricultural fields impacts the quality of food crops grown on Vertisol agricultural fields in Pasuruan. Lead (Pb) released from the exhaust of motor vehicles into the air can eventually enter the soil and be absorbed by plants. This study aimed to examine the effect of Pb from exhaust motor vehicles emission on the Pb status and its behavior in soil, water, and plants. The study was initiated by conducting a survey to determine the sampling locations in selected inundated paddy and maize cropping systems. A stratified random sampling method was used to collect soil, water, and plant samples. The soil of the study area is dominated by Vertisol, with clay content ranging from 54% to 76%. The soil attributes a high cation exchange capacity ranging from 80.53 meq 100 g&lt;sup&gt;-1&lt;/sup&gt; to 93.57 meq 100 g&lt;sup&gt;-1&lt;/sup&gt;. Pb emitted from 2,913,000 vehicles within four months period that entered the agricultural field was not absorbed by paddy and maize crops. Pb entered the soil in the adsorbed form, and no Pb was observed in the soluble form, so it was not absorbed by the roots. In the paddy field, the total Pb of 84.33% was influenced by pollutant distance. Likewise, in the maize field, 83.18% of total Pb was influenced by pollutant distance. The far the pollutant distance from the agricultural field, the lower its total Pb. Paddy field water is adsorbed onto the colloidal clay, which is dispersed due to inundation and sloughing of the paddy, moving with the clay and then dissolved in the water flow.&lt;/p&gt;