Exchangeable Cations Research Articles

Soil carbon stocks in stable tropical landforms are dominated by geochemical controls and not by land use.

Soil organic carbon (SOC) dynamics depend on soil properties derived from the geoclimatic conditions under which soils develop and are in many cases modified by land conversion. However, SOC stabilization and the responses of SOC to land use change are not well constrained in deeply weathered tropical soils, which are dominated by less reactive minerals than those in temperate regions. Along a gradient of geochemically distinct soil parent materials, we investigated differences in SOC stocks and SOC (Δ14 C) turnover time across soil profile depth between montane tropical forest and cropland situated on flat, non-erosive plateau landforms. We show that SOC stocks and soil Δ14 C patterns do not differ significantly with land use, but that differences in SOC can be explained by the physicochemical properties of soils. More specifically, labile organo-mineral associations in combination with exchangeable base cations were identified as the dominating controls over soil C stocks and turnover. We argue that due to their long weathering history, the investigated tropical soils do not provide enough reactive minerals for the stabilization of C input in either high input (tropical forest) or low-input (cropland) systems. Since these soils exceeded their maximum potential for the mineral related stabilization of SOC, potential positive effects of reforestation on tropical SOC storage are most likely limited to minor differences in topsoil without major impacts on subsoil C stocks. Hence, in deeply weathered soils, increasing C inputs may lead to the accumulation of a larger readily available SOC pool, but does not contribute to long-term SOC stabilization.

The use of trophic status indicator as a tool to assess the potential of birch-afforested soils to provide ecosystem services

This study aimed to assess the impact of afforestation of post-arable soils on changes in their potential to provide ecosystem services. An additional aim of the study was to assess the suitability of the Soil Trophic Index (Siedliskowy Indeks Glebowy – SIG in Polish), as an indicator of soil ecosystem services (SESs) regulation, which is a novelty in this type of research. SIG is a number calculated from basic soil properties: TOC and TN contents, the sum of exchangeable alkaline cations, hydrolytic acidity, contents of the Ø < 0.02 mm fraction, bulk density, and soil horizon thickness. It is a number representing the basic properties of a 100 cm × 100 cm × 150 cm soil pedon. The SIG value refers to five categories of soil trophic subtype variants: dystrophic, oligotrophic, mesotrophic, eutrophic, and optionally hypertrophic, which are used to assess the potential of soils to provide ecosystem services. A detailed study was conducted on post-arable sandy and loamy soils afforested with silver birch (Betula pendula Roth) located in two forest districts in central Poland. Each stand covered arable and post-arable plots afforested with silver birch, located on the same soil complex, comprising sandy and loamy soils. Stands were diversified in terms of stand age: 21, 29, 40, 61, and 66-year-old stands on sandy soils, and 15, 33, 41, 61, and 80-year-old stands on loamy soils. At each stand, two soil profiles representing an arable field and a forest were made (20 profiles total). Soil samples were collected from each soil horizon (61 disturbed and 183 undisturbed samples in total). The SIG components were determined under laboratory conditions using standard methods. Based on the obtained results, changes in the potential of post-arable soils to provide certain regulating ecosystem services through afforestation with silver birch were found. The SIG values highlighted diversity in the quality of similarly-textured soils, and thus diversity in their potential to provide the studied regulating SESs. The soils represented almost all trophic types, from dystrophic to eutrophic. Afforestation with silver birch resulted in decreased SIG values in half the cases (mainly in sandy soils), indicating the relatively negative effects of this tree species on the soil system, including lowering the soil’s potential to provide certain regulating ecosystem services. In addition, it was confirmed that the SIG can be used to identify similarities and differences in the potential of similarly-textured soils to provide certain regulating ESs.

Effect of carbon to nitrogen ratio and aeration rate on phosphorus and exchangeable cation contents and their leaching in the soil during olive pomace and turkey manure co-composting

The environmental issues related to olive oil by-products and turkey manure are continuously increasing. This ecological hazard could be mitigated by the composting process. This study aimed to investigate the effect of the initial carbon to nitrogen ratio (C/N) and aeration rate (turning frequency (TF)) on mineral contents (P, K, Ca, and Na) and their leaching in the soil surface. Olive pomace (OP) and turkey manure (TM) were co-composted to prepare six mixtures at three levels of initial C/N (20, 22, and 28) and two levels of TF (once and twice a week). The results revealed a substantial effect of TF, twice a week, resulting in a loss of 36.5%, 36%, and 27% for K, Ca, and Na contents, respectively, whereas TF, once a week, preserves the maximum of nutrients in heaps with good compost maturity.The initial C/N of 28 had significantly reduced P and K by 14% and 13%, respectively, and had increased Ca and Na contents by 85% and 30 %, respectively. The leaching of almost all the studied minerals has been demonstrated after composting. Exchangeable cations have been leached more under heaps with higher C/N ratios with TF of once per week, whereas P leaching has been recorded at the maximum level under the heap with an initial C/N of 20 and turned twice weekly. The resulting composts have generally displayed good mineral quality.

Effects of Exponential N Application on Soil Exchangeable Base Cations and the Growth and Nutrient Contents of Clonal Chinese Fir Seedlings.

Nitrogen (N) is an essential macronutrient for plant function and growth and a key component of amino acids, which form the building blocks of plant proteins and enzymes. However, misuse and overuse of N can have many negative impacts on the ecosystem, such as reducing soil exchangeable base cations (BCs) and causing soil acidification. In this research, we evaluated clonal Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) seedlings grown with exponentially increasing N fertilization (0, 0.5, 1, 2 g N seedling-1) for a 100-day trial in a greenhouse. The growth of seedlings, their nutrient contents, and soil exchangeable cations were measured. We found that N addition significantly increased plant growth and N content but decreased phosphorous (P) and potassium (K) contents in plant seedlings. The high nitrogen (2 g N seedling-1) treated seedlings showed a negative effect on growth, indicating that excessive nitrogen application caused damage to the seedlings. Soil pH, soil exchangeable base cations (BCs), soil total exchangeable bases (TEB), soil cation exchange capacity (CEC), and soil base saturation (BS) significantly decreased following N application. Our results implied that exponential fertilization resulted in soil acidification and degradation of soil capacity for supplying nutrient cations to the soil solution for plant uptake. In addition, the analysis of plants and BCs revealed that Na+ is an important base cation for BCs and for plant growth in nitrogen-induced acidified soils. Our results provide scientific insights for nitrogen application in seedling cultivation in soils and for further studies on the relationship between BCs and plant growth to result in high-quality seedlings while minimizing fertilizer input and mitigating potential soil pollution.

Effect of montmorillonite biochar composite amendment on thallium bioavailability in contaminated agricultural soils and its mitigated health risk.

Little information is available on the effect of clay minerals and biochar composite on the remediation and bioavailability of thallium in agricultural soils. This study thus investigated the influence of montmorillonite biochar composite (Mnt-BC) amendment on the remediation of agricultural soil contaminated artificially by Tl and its potential health risks. Herein, bok choi was cultured to estimate the efficiency of soil Mnt-BC amendments through the bioavailability of Tl of the vegetable. Results showed that Tl bioavailability was significantly reduced in Mnt-BC-amended soils, mainly ascribed to the elevated soil pH and other improved soil properties of high functional groups (-OH, -COOH), negative charges, and exchangeable cations after amendment. Specifically, the highest immobilization efficiency of Tl in soils was observed in 2.5% treated soils with 79.11%, while in plant leaves the highest reduction of Tl was estimated to be 75.1% compared to the control treatment. Hence, the amendment dosage improved the immobilization of Tl in soil and subsequently reduced Tl uptake by the vegetable. Furthermore, from target hazard quotient (THQ) estimation, Mnt-BC amendment can lower the potential health risk while consuming such cultured bok choi in Tl-contaminated soils. Considering the environmental friendliness and high efficiency of Mnt-BC, it could be used as a potential soil amendment to remediate agricultural soils contaminated by Tl.

Reinforced soil salinization with distance along the river: A case study of the Yellow River Basin

Clarifying the relationship between salt-affected soils and their adjacent river systems is critical to address the challenges posed by soil salinization on agricultural production. Among the various biophysical and land management factors linked to soil salinization, few studies have investigated the importance of the distance along the river. Based on the Hetao Irrigation District of the Yellow River Basin, we collected 5314 soil samples and analyzed 17 soil parameters to explore the relationship between salt-affected soils and their distance along the river. Soil salinization was reinforced by the distance along the river, as a trade-off between soil ion accumulation and nutrient regulation. Soil total water-soluble salt content increased by 16.4 mg kg−1 every kilometer, likely due to ions leaching from the soils upstream and partially accumulating in the soils downstream, especially for Cl-, SO42-, and Na+. Greater input and less solubility of Ca2+ based soil amendments, phosphorus fertilizers, and organic materials on the less salt-affected soils upstream may explain the declines in soil Ca2+, available phosphorus, and soil organic matter with distance along the river. With every kilometer along the river, soil exchangeable sodium and cation exchange capacity increased by 8.89 × 10−4 and 1.26 × 10−2 cmol kg−1, respectively, which led to an increase in soil exchangeable sodium percentage by 9.59 × 10−5. The increase in soil exchangeable sodium along the river was mainly due to Na+ accumulation, while soil cation exchange capacity was regulated by soil organic matter and total nitrogen. Soil pH increased by 1.21 × 10−3 per kilometer along the river, associated with the decrease of soil organic matter. Future saline soil amelioration and reutilization initiatives at regional scales may be improved by accounting for the changes in soil physicochemical properties resulting from the distance along the river.

English

In Rwanda, the traditional fired solid bricks embody high fuel consumption and quantity of clay during their molding. Traditional solid bricks are also heavy compared to perforated bricks. This study aimed at investigating the performance of perforated clay bricks made of clay soil (CS) mixed with charcoal waste (CW) as an additive. The physical, chemical and mechanical properties of CS mixed with 0, 10, 30, 40 and 50% of CW were determined. The bricks were extruded manually with the inclusion of a varied number of perforations: 4, 8, 12 and 15 number perforations. The chemical analysis included the determination of organic carbon, exchangeable acidity and chemical components (through XRD) in the soil matrix. The chemical analysis depicted an increase in CaO proportions with an increase in charcoal waste content. There was also an increase in the amounts of exchangeable cations. The research found that with an increase in perforations, weight loss is reduced. However, non-perforated bricks depicted the least abrasion resistance, followed by bricks with 4 perforations. As the CW content increased from 0 to 50%, bricks with 15 and 12 perforations displayed the highest abrasion resistance. The research concludes that an increase in charcoal waste led to an increase in the linear shrinkage of clay soil bricks due to increased calcium cations and reduced magnesium cations in the soil. An optimum of 30% of charcoal waste was identified for the linear shrinkage of clay soil bricks. Bricks having 12 perforations and below with 30% charcoal waste additive can be categorized as category I (load-bearing) bricks.

Soil-Available Nutrients Associated with Soil Chemical and Aggregate Properties following Vegetation Restoration in Western Sichuan, China

The status and drivers of soil-available nutrients in plant-recovered soils are not fully understood, limiting our ability to explore the role of soil-available nutrients in soil geochemical cycling and ecosystem sustainability. Here, we combined the spatial distribution of soil-available nutrients and chemical and aggregate properties from six soil types (subalpine meadow soil, meadow soil, dark brown soil, brown soil, yellow-brown soil, and cinnamon soil) and three horizons (a leaching horizon, sediment horizon, and parent material horizon) to study the status and drivers of soil-available nutrients. Our findings reveal that the soil-available nitrogen (AN) ranged from 72.33 to 169.67 mg/kg, the soil-available phosphorus (AP) ranged from 1.77 to 75.90 mg/kg, and the soil-available potassium (AK) ranged from 46.43 to 88.55 mg/kg in the six soil types. The subalpine meadow soil and the dark brown soil had the highest soil AN, with means of 169.67 and 139.35 mg/kg, respectively. The brown soil had the highest soil AP, with a mean of 75.9 mg/kg, and the dark brown soil and the brown soil had the highest soil AK, with means of 83.49 and 88.55 mg/kg, respectively. The results show that the soil types and soil depths had a significant impact on the status of AN, AP, and AK (p &lt; 0.05). Moreover, a higher cation exchange capacity (CEC), the macro-aggregate contents (with 2–1 mm and 1–0.5 mm particle sizes) of the non-water-stable aggregates, and the macro-aggregate content and stability (2–1 mm particle size and geometric mean diameter (GMD) of the water-stable aggregates were deemed to facilitate soil-available nitrogen because of the positive correlations (p &lt; 0.05). Lower exchangeable cations (ECs) and the micro-aggregate content (≤0.1 mm particle size) of the water-stable aggregates and higher soil cations helped in the accumulation of soil-available phosphorus and soil-available potassium, respectively. Moreover, the regulation of the soil chemical and aggregate properties was found to vary with soil type and horizon in a correlation analysis. Together, our results provide insights into the importance of chemical and aggregate properties in regulating soil nutrient availability across soil types, as well as providing strong support for the inclusion of soil resource utilization in regional forest restoration and management.

Long-term manure fertilization increases rill erosion resistance by improving soil aggregation and polyvalent cations

Application of organic fertilizers is a potential practice to prevent soil erosion by changing the physicochemical properties of the soil, such as macroaggregates, soil organic carbon (SOC) content, and exchangeable cations. However, the practical performance of organic fertilizer in soil erosion after a long-term application has scarcely been reported. To reveal the response of soil erosion resistance (i.e., the soil susceptibility to resist external erosion force) to 43 years of organic fertilization, five treatments were investigated: (1) CK (no fertilizer), (2) NPK (mineral fertilizer), (3) M (pig manure), (4) MN1 (pig manure + 138 kg N ha−1), and (5) MN2 (pig manure + 276 kg N ha−1). The results showed that NPK, M, MN1, and MN2 significantly increased soil critical shear stress (τc) by 54 %, 87 %, 101 %, and 67 %, respectively, compared to CK. However, rill erodibility (kd) was increased significantly only in the MN2 treatment. The optimal partial least squares regression model showed that the increase in soil exchangeable Ca2+ was the dominant contributor to the τc increase, while soil mean weight diameter (MWD) had the greatest negative effect on kd. Compared with CK, the soil exchangeable Ca2+ in M and MN1 increased significantly by 123 % and 135 %, respectively. The MWD in M and MN1 increased by 86 % and 83 %, respectively, compared with that in CK. The application of pig manure was beneficial for decreasing exchangeable Na+ and increasing SOC content, which could improve MWD. Manure with a high N content did not increase MWD due to SOC decomposition. Our results indicate that the long-term application of manure, alone or combined with moderate N, improves rill erosion resistance.

Neutralization Short-Circuiting with Weak Electrolytes Erodes the Efficiency of Bipolar Membranes.

Bipolar membranes (BPMs) are critical components of a variety of electrochemical energy technologies. Many electrochemical applications require the use of buffers to maintain stable, nonextreme pH environments, yet the impact of buffers or weak acids/bases on the electrochemical behavior of BPMs remains poorly understood. Our data for a cell containing weak electrolytes is consistent with internal pH gradients within the anion exchange membrane (AEM) or cation exchange membrane (CEM) component of the BPM that form via ionic short-circuiting processes at open-circuit. Short-circuiting results from the coupling of co-ion crossover and parasitic neutralization and leads to buffering of the bipolar interface. This phenomenon, which we term neutralization short-circuiting, serves to erode BPM efficiency by attenuating the open-circuit membrane voltage and introducing parasitic reverse bias currents associated with weak acid/base dissociation at the interface. These findings establish a mechanistic basis for the operation of BPM cells in the presence of weak acid/base electrolytes.

Facile preparation and enhanced photocatalytic hydrogen evolution of cation-exchanged zeolite LTA supported TiO2 photocatalysts

Photocatalytic hydrogen evolution (PHE) is an attractive green way to produce clean energy. Zeolite-supported titanium dioxide (TiO2) offers a cost-efficient pathway to prepare an efficient and recyclable photocatalyst for PHE. As known, zeolite has an excellent cation exchange capacity, and the exchangeable cations show considerable influence on its properties. However, the effect of exchangeable cations within zeolite-supported TiO2 photocatalysts on their PHE activity remains unclear. Here, we prepared a series of zeolite LTA-supported TiO2 photocatalysts (TXA, X = Na, K, Ca) with various cations (Na+, K+, Ca2+) inside the zeolite and investigated the effect of cations on their PHE activity. The results demonstrated that all TXA photocatalysts exhibit significantly enhanced PHE activity, and TCaA shows the highest hydrogen evolution rate, which is 3.84 times higher than that of P25. According to experimental results, TCaA possesses a higher solid-acid concentration and a larger surface area, which provides more proton sources and active sites for PHE, facilitates charge separation, and reduces photogenerated electron-hole pair recombination. We believe this work will offer a new exploration strategy for regulating the PHE performance of zeolite-supported TiO2-based photocatalysts and shed new light on the rational design of cost-efficient PHE catalysts.

Identification and characterization of the key lethal toxin from jellyfish Cyanea nozakii

Jellyfish Cyanea nozakii venom is a complex mixture of various toxins, most of which are proteinous biological macromolecules and are considered to be responsible for clinical symptoms or even death after a severe sting. Previous transcriptome and proteome analysis identified hundreds of toxins in the venom, including hemolysins, C-type lectin, phospholipase A2, potassium channel inhibitor, metalloprotease, etc. However, it is not clear which toxin in the venom plays the most important role in lethality. Herein, we isolated the key lethal toxin (Letoxcn) from jellyfish Cyanea nozakii using anion exchange chromatography, size-exclusion chromatography, and cation exchange chromatography. The molecular weight of Letoxcn is ∼50 kDa with the N-terminal sequences of QADAEKVNLPVGVCV. Peptide mass fingerprinting analysis of Letoxcn shows that it may have some motifs of phospholipase, metalloproteinase, thrombin-like enzyme, potassium channel toxin, etc. However, only metalloproteinase activity but no hemolytic, PLA2, or blood coagulation activity was observed from in vitro toxicity analysis. Overall, this study uncovered and characterized the key lethal toxin in the venom of jellyfish Cyanea nozakii, which will not only help to reveal the molecule mechanism of the lethality, but also develop effective treatment like antivenom for this jellyfish sting in the future.

EFFECT OF VERMICOMPOST ASSOCIATED WITH MYCORHIZAL FUNGI ON THE GROWTH OF EGGPLANT IN ORGANIC GREENHOUSE AGRICULTURE

&lt;p&gt;&lt;strong&gt;Background&lt;/strong&gt;. In West Africa, the eggplant crop participates in the fight against rural poverty, hunger and malnutrition due to their higher nutritional contents. However, this crop is faced with several constraints including poor soils and low yielding cultivars. It is known that mycorhization of plants improves plant nutrition while preserving them from certain pests. &lt;strong&gt;Objective.&lt;/strong&gt; To evaluate the combination of mycorhization and vermicompost effect on eggplant plants growth and yield. &lt;strong&gt;Methodology.&lt;/strong&gt; A consortium of arbuscular mycorrhizal (AM) from forest soils was trapped using maize roots and used as inoculum for eggplant, Djamba F1 variety. A trial using this inoculum combined or not to vermicompost was carried out for 90 days under a greenhouse. Selected soil properties, eggplant growth and yield indicator were recorded at the end of trial. &lt;strong&gt;Results.&lt;/strong&gt; As expected, soil vermicompost alone or combined to inoculum displayed an increase of soil parameter such as pH, exchangeable base cations, total organic matter, total nitrogen compared to control and soil with AM alone. Soil with AM alone had a limited impact on the growth and yield of eggplant. In contrast, all treatments including vermicompost (vermicompost alone and vermicompost + AM) showed a significant increase of eggplant growth parameters and yield’s indicators. &lt;strong&gt;Implications.&lt;/strong&gt; These results highlighted a need to carry out a screening of mycorrhizal fungi from eggplant production areas to isolate and identify the efficient strains of mycorrhizal fungi for symbiosis with eggplant under tropical conditions. &lt;strong&gt;Conclusion. &lt;/strong&gt;The vermicompost significantly improved the growth of the eggplant. Its coupling with a consortium of spores of the genera&lt;em&gt; &lt;/em&gt;results in better plant growth and yield. This combination has a significant effect on the studied parameters (height, crown diameter, biomass and yield). &lt;/p&gt;

Study of the Temperature-Programmed Desorption of Carbon Dioxide (CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;) on Zeolites X Modified with Bivalent Cations

Study of physisorbed and chemisorbed carbon dioxide (CO2) species was carried out on the NaX zeolite modified by cationic exchanges with bivalent cations (Ca2+ and Ba2+) by temperature-programmed desorption of CO2 (CO2-TPD). Others results were obtained by infrared to complete the study. The results of this research showed, in the physisorption region (213 - 473 K), that the cationic exchanges on NaX zeolite with bivalent cations increase slightly the interactions of CO2 molecule with adsorbents and/or cationic site. Indeed, the desorption energies of physisorbed CO2 obtained on the reference zeolite NaX (13.5 kJ·mol-1) are lower than that of exchanged zeolites E-CaX and E-BaX (15.77 and 15.17 kJ·mol-1 respectively). In the chemisorbed CO2 region (573 - 873 K), the desorption energies related to desorbed species (bidentate carbonates: CO32-) on the exchanged zeolites E-CaX and E-BaX are about 81 kJ·mol-1, higher than the desorbed species (bicarbonates: HCO32-) on the reference R-NaX (62 kJ·mol-1). In addition, the exchanged E-BaX zeolite develops the secondary adsorption sites corresponding to bicarbonates species with desorption energies of 35 kJ·mol-1 lower to desorption energies of bicarbonates noted on the reference zeolite NaX.

Soil properties of agricultural sloping land in Banjarnegara Regency, Indonesia

Intensive farming in highland sloping land can lead to more frequent soil erosion, thus exacerbating soil deterioration. Good agricultural practices on sloping land can prevent soil degradation. This study aimed to identify soil properties within transects consisting of the shoulder slope (forest) and upper and lower slopes (agricultural field) in steep slope ranges between 25 – 40%. The study area was located in Sumberejo village, Banjarnegara Regency, Indonesia, with young coffee tree intercropping carrot land use previously planted with horticulture crops. The result showed that the concentration of potential P and K, pH, N, exchangeable cation (Ca, Mg, K), and CEC within the transect in sloping land resulted in higher concentration in the upper and lower slope than shoulder slope because agriculture area got influence from fertilizer application. Higher soil organic carbon content and dehydrogenase enzyme also lower bulk density value in shoulder slope because the forest had undisturbed condition. This study informs that agricultural activities influence soil characteristics. Implementing proper land management on sloping lands can reduce soil degradation and mitigate the effects of climate change.

MORFOLOGI DAN KLASIFIKASI TANAH PADA FORMASI PENIRON BAHAN INDUK ANDESIT PIROKSEN DI DESA PAGEDONGAN, BANJARNEGARA

Rock formation as parent material in Pagedongan Village, Banjarnegara influences the properties of the soil formed. The purpose of this research was to identify the morphology and soil classification according to USDA Taxonomy, National Soil Classifications, and World Reference Base for Soils. This study uses a survey method by determining observation points based on a rock formation, namely Peniron Formation, with pyroxene andesite as parent material for observing soil morphology, physical and chemical of soil in the field, then laboratory analysis included soil texture, bulk density, organic C, soil pH H2O and KCl, exchangeable cations K, Ca, Mg, Na, CEC, and base saturation. The results showed that the soil developed in the Peniron Formation with pyroxene andesite as parent material had morphology with diagnostic horizons of umbric epipedon and argillic endopedon. The results showed that the soil classification according to USDA Taxonomy is Typic Palehumults Isohyperthermic, according to National Soil Classifications is Podsolics Ortoxic, and according to World Reference Base for Soils is Loamic Abruptic Alfisols.

The impact of cow dung augmentation on soil restoration and bio-accumulation of metals (Lead and Cadmium) in Pheretima posthuma (Annelida: Clitellata).

To investigate the role of cow dung in soil reclamation and bio assimilation along with bio accumulation of heavy metals in earthworm (P. posthuma) (N=900) earthworms were used and treatment groups of CD-soil mixture of different proportion of cow dung were designed. Nonlethal doses of lead acetate and cadmium chloride were added in treatment groups. Mature P. posthuma were released in each experimental pot maintaining the favorable conditions. The pH, carbon, nitrogen, phosphorus, exchangeable cations, and heavy metal level of each mixture was evaluated. The results indicated that bio-assimilation of Pb and Cd by P. posthuma were significantly (P ˂ 0.01) higher in different soil-CD treatments compared to control. Highest bio-assimilation of both metals was observed in T1 of both groups (Pb = 563.8 mg/kg and Cd = 42.95 mg/kg). The contents of both metals were significantly (P ˂ 0.05) lowered in casting. The nutrient concentration in the final castings of all soil-CD treatments were also equally transformed from less or insoluble to more soluble and available for plants, except for carbon level which increased with CD proportion. It is concluded that cow dung as organic matter has a positive effect on soil reclamation and bio-assimilation of metals by P. posthuma.

Prilog poznavanju nekih fizičkih i hemijskih osobina krečnjačkih zemljišta planinskog masiva Ozren

Soils formed on limestones occupy large area in Serbia, but there is not a lot of information about their properties. This paper presents physical and chemical properties of the Brownized Calcomelanosols and Moderately-deep Calcocambisols of the Ozren Mountain. Brownized Calcomelanosols under natural grassy vegetation were investigated at the Vlasina pass, whereas Calcocambisols under mixed forests were investigated near the site "Ozrenske livade". Soil profiles were excavated up to the parent material, and disturbed and undisturbed soil samples were collected from soil genetic horizons. Following soil characteristics were determined: particle size distribution, soil structure and water resistance of structural aggregates, bulk density, total porosity, air capacity, water-holding capacity, water conductivity, pH, content of humus, available phosphorus (P2O5) and potassium (K2O), hydrolytic acidity, cation exchange capacity (CEC), sum of exchangeable base cations, and base saturation. Humus-accumulative horizon (Amo) of the Brownized Calcomelanosols has silty clay texture, whereas the cambic (B)rz horizon of both soils has a clay texture. The Amo horizon of Calcomelanosols is characterized by fine to medium granular structure (0.5-5 mm) of very high water resistance. The total porosity, air capacity and water permeability of both soils is high. Their water-holding capacity is high. Amo horizon of Calcomelanosols is characterized by a high humus content (&gt;10%). Soil reaction in water of Amo horizon is neutral, whereas in (B)rz horizons both soils are moderately acid. Both soils have high CEC (&gt;58 cmol kg-1 ) and base saturatation (&gt;95%). Brownized Calcomelanosol is moderately to highly supplied with available K2O, whereas Calcocambisol is moderately supplied; while both soils are very poor in available P2O5. Since this study presents quite favorable physical and chemical properties of the investigated soils due to the conservation of natural forests and grasslands, the results can help in a deeper understanding of soil ecology and the preservation of natural plant cover.

Water adsorption on acetylene black carbon

Differential heat, isotherm, thermokinetics, and entropy of water adsorption on the black carbon were studied by the adsorption-calorimetric method at 303 K. The adsorption mechanism, type, and number of formed ion-molecular complexes were determined. Thermokinetics of adsorption on the black carbon and the law of migration of exchange cations were determined, and the adsorption energy of gases and vapors was calculated. The adsorption isotherm is described by the two-and three-dimensional mathematical equations of the volume-saturation theory of micro-pores (TVSM).

Adsorption of Rare Earth Metal Cations by Base Metal Sulfides in the Broken Spur and TAG Hydrothermal Fields, Atlantic Ocean

The article presents the results of sorption of rare earth metal cations on samples of deepsea polymetallic sulfides of the hydrothermal fields of the Broken Spur and TAG of the Mid-Atlantic Ridge. The main minerals of these samples were respectively marcasite, pyrrhotine, pyrite, sphalerite and chalcopyrite, pyrite, and marcasite. It has been established that these sulfide minerals of iron, copper and zinc are natural adsorbents. The exchange capacity of sulfide minerals for rare earth metal cations is in the range of 0.006‒0.061 mg-eq/g. The exchange complex of sulfide minerals consists of cations of alkaline, alkaline-earth metals and basic cations of metals of the crystal lattice – Fe, Zn, Cu (in very limited quantities). The mechanism of absorption of rare earth metal cations is ion-exchange, equivalent to the exchange cations of sulfide minerals. It was found that in the composition of sulfide minerals, rare earth metal cations are almost completely in sorbed form (more than 90% of the total amount); The chemically bound form can be, apparently, only for Lu and Dy cations. The mineral composition of sulfide deposits is preserved in the products of exchange reactions, new phases do not appear.