Red Clay Soil Research Articles

Corrosion Behavior of Copper-Clad Steel Bars with Unclad Two-End Faces for Grounding Grids in the Red Clay Soil

Iron-aluminum oxides in the red soil have a significant impact on the corrosion behavior of the metal for grounding grids. Effects of iron-aluminum oxides on the corrosion behavior of the cross section of copper-clad steel in the red soil have been investigated using electrochemical impedance spectroscopy and Tafel polarization. All the data indicate that the iron-aluminum oxides can promote the corrosion of copper-clad steel in the red soil. The corrosivity of the red soil greatly increases after iron-aluminum oxides are added into the soil. Iron-aluminum oxides promote galvanic corrosion of copper-clad steel and increase the corrosion degree of the center steel layer. The iron-aluminum oxides stimulate corrosion process of copper-clad steel acting as a cathodic depolarizing agent. XRD results further validate that the corrosion products of the copper-clad steel bar mainly consist of Fe3O4 and Cu2O.

ESTUDO E MODELAGEM DO CRESCIMENTO EM DIÂMETRO DE POVOAMENTOS DE <i>Pinus taeda</i> L. SUBMETIDOS A PODAS E DESBASTES NA ARGENTINA

A presente pesquisa foi realizada com o objetivo de estudar e modelar o efeito dos desbastes pré-comerciais e das podas no crescimento diamétrico, em um povoamento de Pinus taeda L. de 15 anos de idade, no Nordeste da Argentina. O estudo localizou-se em solo vermelho argiloso profundo com um delineamento sistemático de faixas para intensidades de desbastes e subfaixas para intensidades de podas. Os tratamentos de desbaste, realizados aos 3 anos de idade, foram: 1666 (sem desbaste); 833; 416 e 208 árvores ha-1. As podas foram realizadas a partir dos 3 anos e com frequência anual por 2, 3 ou 4 anos consecutivos, com remoção de 30, 50 e 70% da copa viva, respectivamente. O modelo geral obtido por regressão linear permitiu estimar o diâmetro da árvore de área basal média (dg) em função da idade com boa precisão (desvio médio absoluto em percentagem igual a 5.71), sendo as variáveis: árvores remanescentes, copa remanescente e número de podas consideradas nos modelos estimadores dos coeficientes da função geral. Aos 15 anos de idade, os diâmetros variaram entre 25.6 e 41.5 cm, para as densidades de 1666 e 208 árvores ha-1, respectivamente, sem poda. O crescimento do dg foi afetado negativamente pelas podas e positivamente pelos desbastes.

Sorption of surfactants and personal care products in Indian soils

Sorption of three surfactants and personal care products in four types of commonly occurring Indian soils was extensively studied. The soils used in the study were red soil, clay soil, compost soil and sandy soil as classified by American Society for Testing and Materials (ASTM). The three surfactants used in the study were representative of cationic, non-ionic and anionic surfactant groups. The sorption of surfactants followed the descending order: sodium dodecyl sulphate (SDS) > trimethyl amine (TMA) > propylene glycol (PG). The maximum adsorption capacity (Qmax) was obtained in compost soil (28.6 mg/g for SDS; 9.4 mg/g for TMA and 4 mg/g for PG). The rate of adsorption was the maximum in compost soil followed by clay and red soils, and minimum for sandy soils. It is found that the Freundlich model fits the isotherm data better than the Langmuir model. Freundlich coefficient (K f) increased as the organic content of soils increased. Desorption of target pollutants in tap water was 20–50% whereas acid desorbs 40–90% of target pollutants from soil matrix. It was also found that the adsorption and desorption were significantly affected by the presence of clay and organic matter. The results also indicate that surfactants and personal care products, especially TMA and PG, are highly mobile in sandy soil followed by red soil. Therefore, immobilization of target pollutants is most economical and effective in compost and clayey soils whereas for other type of soils the combination of physiochemical and biological process will be effective option for remediation.

Using Qualitative Methods to Explore Lay Explanatory Models, Health-Seeking Behaviours and Self-Care Practices of Podoconiosis Patients in North-West Ethiopia.

BackgroundPodoconiosis (endemic non-filarial elephantiasis) is a chronic, non-infectious disease resulting from exposure of bare feet to red-clay soil in tropical highlands. This study examined lay beliefs about three under-researched aspects of podoconiosis patients’ care: explanatory models, health-seeking behaviours and self-care.MethodsIn-depth interviews and focus group discussions were undertaken with 34 participants (19 male, 15 female) between April-May 2015 at podoconiosis treatment centres across East and West Gojjam regions in north-west Ethiopia.ResultsExplanatory models for podoconiosis included contamination from blood, magic, soil or affected individuals. Belief in heredity or divine punishment often delayed clinic attendance. All participants had tried holy water treatment and some, holy soil. Herbal treatments were considered ineffectual, costly and appeared to promote fluid escape. Motivators for clinic attendance were failure of traditional treatments and severe or disabling symptoms. Patients did not report self-treatment with antibiotics. Self-care was hindered by water being unavailable or expensive and patient fatigue.ConclusionA pluralistic approach to podoconiosis self-treatment was discovered. Holy water is widely valued, though some patients prefer holy soil. Priests and traditional healers could help promote self-care and “signpost” patients to clinics. Change in behaviour and improving water access is key to self-care.

Effect of foliar application of water soluble fertilizers on growth, yield and economics of chickpea (Cicer arietinum L.)

A field experiment was conducted during rabi, 2012-13 and 2013-14 on red sandy clay loam soil to study the effect of foliar application of water soluble fertilizers on chickpea. The experiment consisted of fifteen treatments which were replicated thrice in RCB Design. Results indicated that spray of water soluble fertilizer (19:19:19) at 1.5 % concentration at flowering and pod development stage along with basal application of fertilizers (13.5: 25: 25 kg N, P2O5, K2O) significantly increased growth attributes, yield and benefit cost ratio in chickpea cultivation. Further increase in spray concentration up to 2.0 % did not significantly improve the performance of chickpea.

The Remediation of Chromium (VI)-Contaminated Soils Using Microbial Fuel Cells

ABSTRACTChromium (VI) is a priority pollutant in soil and water and poses serious threats to the environment. Microbial fuel cells (MFCs), as a sustainable technology, have been applied to treat heavy-metal-contaminated wastewater. To study MFC application in soil remediation, red clay soil and fluvo-aquic soil were spiked with Cr(VI) and packed into a cathode chamber of MFCs, which were then operated at external resistances of 100 and 1000 Ω for 16 days, with open circuit condition as a control treatment. After the operation, the concentration of dissolved Cr(VI) in supernatant and total Cr(VI) in soil was decreased. Soil type and external resistance significantly affected the current, removal efficiency of Cr(VI), and cathode efficiency. Reducing external resistance improved the removal efficiency. The red soil generated a higher current of MFCs, but showed a lower removal efficiency and cathode efficiency than fluvo-aquic soil, implying that the red soil may contain more electron acceptors that competed with Cr(VI) reduction reaction. Our study demonstrated that MFC-based technology has the potential to remediate Cr(VI)-contaminated soil; the efficiency varied between soil types and can be improved with high current.

Effect of Calcium Sulphate on the Geotechnical Properties of Stabilized Clayey Soils

An experimental investigation was undertaken to study the effect of calcium sulphate (CaSO 4 .2H 2 O) on the behaviour of the grey clay (GS) and red clay (RS) soils stabilized with lime (L), natural pozzolana (NP) and their combination (L-NP). In this study, the geotechnical properties investigated are respectively, the Atterberg limits on samples cured for 1 to 30 days to assess the diffusion time effect of CaSO 4 .2H 2 O (DTC) in the soil paste and the unconfined compressive strength (UCS) on samples cured for 7 to 120 days. The results show that both GS and RS samples can be successfully stabilized with L alone or with L-NP which substantially reduce their plasticity index (PI) and increase their UCS. On the other hand, a negligible effect was reported when the NP is used alone. However, when combining a fraction of CaSO 4 .2H 2 O to samples containing L or L-NP, a further decrease in the PI is observed. In addition, higher UCS values are recorded.

Utilization of Hairy Footed Flower Bee <i> Anthophora plumipes</i> (Hymenoptera: Apidae) for Pollination of Greenhouse Strawberry

Pollination efficiency of hairy footed flower bee Anthophora plumipes for greenhouse strawberry was evaluated in a small greenhouse located in Shimane University, Matsue, Japan (lat. 35°29', long. 133°27' and elevation 170 m). Twenty five female and six male bees were released in a greenhouse on April 15, 2014. Red clay soil blocks were provided as the nesting materials. Two hundred and fifty pots of strawberry (Fragaria annanasa) were allocated for the following three treatments: 1) no supplementary pollination (control), 2) hand pollination, and 3) bee pollination. Both male and female bees effectively foraged flowers throughout the day. Rate of fertilized seed by the bee pollination was significantly greater than no supplementary pollination (control) and similar to that in the hand pollinated flowers. Quality of the fruits (evaluated based on the shape and deformity) was also improved by the bee pollination. A. plumipes effectively pollinated strawberry flowers in the greenhouse and could be developed as an alternative pollinator for this crop.

Transport of gadolinium- and arsenic-based pharmaceuticals in saturated soil under various redox conditions.

The release of pharmaceuticals and personal care products (PPCPs) to the soil-water environment necessitates understanding of PPCP transport behavior under conditions that account for dynamic flow and varying redox states. This study investigates the transport of two organometallic PPCPs, Gd-DTPA and roxarsone (arsenic compound) and their metal salts (Gd(NO3)3, AsNaO2); Gd-DTPA is used widely as a contrasting agent for MRI, while roxarsone is applied extensively as a food additive in the broiler poultry industry. Here, we present column experiments using sand and Mediterranean red sandy clay soil, performed under several redox conditions. The metal salts were almost completely immobile. In contrast, transport of Gd-DTPA and roxarsone was affected by the soil type. Roxarsone was also affected by the different redox conditions, showing delayed breakthrough curves as the redox potential became more negative due to biological activity (chemically-strong reducing conditions did not affect the transport). Mechanisms that include adsorptive retardation for aerobic and nitrate-reducing conditions, and non-adsorptive retardation for iron-reducing, sulfate-reducing and biologically-strong reducing conditions, are suggested to explain the roxarsone behavior. Gd-DTPA is found to be a stable complex, with potential for high mobility in groundwater systems, whereas roxarsone transport through groundwater systems is affected by redox environments, demonstrating high mobility under aerobic and nitrate-reducing conditions and delayed transport under iron-reducing, sulfate-reducing and biologically-strong reducing conditions.

Field corrosion characterization of soil corrosion of X70 pipeline steel in a red clay soil

The corrosion behavior of X70 pipeline steel buried in red soil environment has been studied. The surface morphology and elemental distribution were determined by scanning electron microscopy (SEM),energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The corrosion kinetics was evaluated by weight loss measurement. The results show that in red soil, the corrosion rate of X70 steel decreases with time, and follows the exponential decay law. General corrosion with non-uniform and localized pitting occurred on the steel surface. α-FeOOH was the dominate products during corrosion in whole buried periods, and the corrosion products exhibited well protective properties. The potentiodynamic polarization tests revealed that icorr decreased with time, indicating the improvement of corrosion resistance. The results of Electrochemical impendence spectroscopy (EIS) are consistent with potentiodynamic polarization tests.

Influence of the insecticides acetamiprid and carbofuran on arylamidase and myrosinase activities in the tropical black and red clay soils.

The objective of this study was to determine the effects of two insecticides, namely, acetamiprid and carbofuran on the enzymatic activities of arylamidase (as glucose formed from sinigrin) and myrosinase (as β-naphthylamine formed from L-leucine β-naphthylamide) in the black and red clay soils collected from a fallow groundnut (Arachis hypogaea L.) fields in the Anantapur District, Andhra Pradesh, India. The study was realized within the framework of the laboratory experiments in which the acetamiprid and carbofuran were applied to the soils at different doses (1.0, 2.5, 5.0, 7.5, 10.0 kg ha(-1)). Initially, the physicochechemical properties of the soil samples were analyzed. After 10 days of pesticide application, the soil samples were analyzed for the enzyme activities. Acetamiprid and carbofuran stimulated the arylamidase and myrosinase activities at lower concentrations after 10 days incubation. Striking stimulation in soil enzyme activities was noticed at 2.5 kg ha(-1), persists for 20 days in both the soils. Overall, higher concentrations (5.0-10.0 kg ha(-1)) of acetamiprid and carbofuran were toxic or innocuous to the arylamidase and myrosinase activities. Nevertheless, the outcomes of the present study clearly indicate that the use of these insecticides (at field application rates) in the groundnut fields (black and red clay soils) stimulated the enzyme (arylamidase and myrosinase) activities.

English

For the first time, natural seed germination in cultivated population of Cassia fistula Linn. is reported in this paper. Natural seed germination occurred under many mother trees at Covenant University, Ota, Ogun State, Nigeria; while no germination occurred under some other mother trees. Random soil samples were taken in representative areas and analysed. Seedling dynamics were also investigated by fencing the seedlings around five mother trees, mapping and following their survival with time. Soil samples obtained where there was germination are loose, black soils with high moisture and humus contents and mean pH of 7.2 while soil samples obtained where there was no germination are hard, red lateritic clay soils with significantly lower moisture and humus contents and mean pH of 6.4. The seedlings study showed that some seedlings were more or less in a straight line from broken and rotted pods buried in the soil or covered in debris. Other seedlings were single, in pairs or in groups of three or four. A seed germinated within a pod and grew out of a small hole in the pod, with the radicle coming out first and by the next day, the cotyledons emerged. In the first few weeks of study, the number of seedlings in each fenced area increased with time, thereafter the number decreased accompanied by yellowing of leaves. There was also increased growth of surrounding weeds mainly grasses, as well as about 60% reduction in light intensity on the seedling floor due to the development of new foliage on the mother trees. The reduced number of seedlings under the mother trees was attributed to increased inter specific competition as well as reduced light intensity reaching the seedlings since C. fistula is not shade tolerant. Consequently, cultivated C. fistula like the natural population may not regenerate well in nature and its continued existence may depend on artificial conservation through its use as ornamental and medicinal plant.   Key words: Natural germination, seedling dynamics, cultivated population, Cassia fistula, Nigeria.

Podoconiosis, the Non-Filarial Elephantiasis, a Means of Discrimination and Poverty in Ethiopia

Podoconiosis is a non-infectious geo-chemical disease caused by exposure of bare feet to red clay soil derived from volcanic rocks. In Ethiopia, 1 million people suffer with the disease. It affects the physical condition (disability and deformity) of patients and also the social and economic status of affected individuals. Studies conducted in endemic countries clearly stated that there is stigmatization in the family and in general in the community. This consequences mental distress in affected individual. Besides, individuals affected economically: they cost for treatment and mainly they loss their productivity potential. These results financial crisis individually and aggravate poverty in the society. This review intends to address the social exclusion and economic impact of podoconiosis in Ethiopia.

Barriers to access and re-attendance for treatment of podoconiosis: a qualitative study in northern Ethiopia.

Podoconiosis is a chronic non-infectious lymphoedema affecting individuals exposed to red clay soil in endemic areas. Evidence from International Orthodox Christian Charities (IOCC) treatment centers' registers suggests that a significant proportion of registered patients with podoconiosis fail to re-attend for treatment, putting them at risk of worsening disability associated with the lymphoedema and attacks of acute adenolymphangitis. The aim of this study was to explore barriers to access and re-attendance of patients with podoconiosis in northern Ethiopia. A cross-sectional qualitative study was conducted at three IOCC treatment sites from February to April 2013. Twenty-eight patients and three project leaders took part in in-depth interviews. Three focus group discussions were undertaken with 22 patients, patient association leaders and project staff members. Barriers to access and to continued attendance at treatment centers were recognized by all participant groups. The following reasons were reported: lay beliefs about the disease's causation and presentation, occupational, geographic and financial barriers, stigma and conflicting expectations of treatment services. This study illustrates the multiple, step-wise barriers to accessing treatment faced by podoconiosis patients. These factors are dynamic, frequently interact and result from competing social and economic priorities.

Parental material and cultivation determine soil bacterial community structure and fertility.

Microbes are the key components of the soil environment, playing important roles during soil development. Soil parent material provides the foundation elements that comprise the basic nutritional environment for the development of microbial community. After 30 years artificial maturation of cultivation, the soil developments of three different parental materials were evaluated and bacterial community compositions were investigated using the high-throughput sequencing approach. Thirty years of cultivation increased the soil fertility and soil microbial biomass, richness and diversity, greatly changed the soil bacterial communities, the proportion of phylum Actinobacteria decreased significantly, while the relative abundances of the phyla Acidobacteria, Chloroflexi, Gemmatimonadetes, Armatimonadetes and Nitrospira were significantly increased. Soil bacterial communities of parental materials were separated with the cultivated ones, and comparisons of different soil types, granite soil and quaternary red clay soil were similar and different with purple sandy shale soil in both parental materials and cultivated treatments. Bacterial community variations in the three soil types were affected by different factors, and their alteration patterns in the soil development also varied with soil type. Soil properties (except total potassium) had a significant effect on the soil bacterial communities in all three soil types and a close relationship with abundant bacterial phyla. The amounts of nitrogen-fixing bacteria as well as the abundances of the nifH gene in all cultivated soils were higher than those in the parental materials; Burkholderia and Rhizobacte were enriched significantly with long-term cultivation. The results suggested that crop system would not deplete the nutrients of soil parental materials in early stage of soil maturation, instead it increased soil fertility and changed bacterial community, specially enriched the nitrogen-fixing bacteria to accumulate nitrogen during soil development.

Corrosion Behavior of Galvanized Steel for Grounding Grids in the Red Clay Soil

The corrosion behavior of galvanized steel for grounding grids in the red clay soil was studied by electrochemical impedance spectroscopy (EIS) and polarization curve measurement. The results show that the Iron-Aluminitma oxides can promote the galvanized steel corrosion in red solution. The resistance decreased with the increase of immersion time and the latter stage is less than the early stage. The corrosion current density of galvanized steel decreased with the increase of the content of Iron-Aluminitma oxides of soil solution.

Temporal variations of accumulated cesium in natural soils after an uncharacteristic external exposure

The accumulation behaviors and solid phase partitioning patterns of stable cesium, which have been recognized as an indicator of the long-term movement of radioactive cesium (137Cs or 134Cs) in ecosystems, were studied in typical and natural soils of Japanese origin, namely, red clay, leaf-mold and andosol soils. The retention and migration of soil-phase cesium have been explained relative to various factors, such as soil organic matter contents, competitive cation concentrations and the adsorption ratio of Cs to the solid phase. Cesium was adsorbed nearly quantitatively in the leaf-mold type soil, and the rate of Cs absorption increased as the particle size decreased in the red clay and andosol soils. The distributions of Cs within the soil solid phases were defined using the selective sequential extraction scheme and were used to explain its relative incorporation in the soil fractions. Solid phase fractionation indicated that nearly half of the total cesium concentrations in the soils were in the ‘residual’ fraction (representing the metal that was incorporated within the crystalline lattice of the soil and was difficult to extract). These findings are expected to provide information regarding suitable conditions for remediation, immobilization or the recovery of cesium from contaminated soils with excess cesium concentrations.

Origin of the high sensitivity of Chinese red clay soils to drought: Significance of the clay characteristics

The red clay soils which are widespread in China are known to be highly sensitive to drought during the dry season but the origin of this high sensitivity to drought remains unclear. Several red clay soils were selected in the Hunan province for study. We studied their basic physico-chemical properties and clay mineralogy, their structure and shrinkage properties, as well as their water retention properties. Results show that the amount of water available between −330 and −15,000hPa water potential is consistent with that recorded in many other clay soils from different parts of the world and thus cannot explain the high sensitivity of the red clay soils to drought. This high sensitivity to drought might be related to the high proportion of poorly available water which was characterized by the amount of available water between −3,300 and −15,000hPa water potential. Comparison with clay soils located in different parts of the world and for which the sensitivity to drought was not identified showed that this proportion of poorly available water is indeed much higher in the red clay soils studied than in clay soils representing a large range of both clay content and mineralogy. This specific behavior of the red clay soils studied is thought to be related to the history of their parent materials: these materials are continental sediments which may have been submitted to great hydric stress, thus leading to strongly consolidated soils with consequences such as a high proportion of poorly available water, strong aggregation and weak shrinkage properties.

Biodegradation of eucalyptus urograndis wood by fungi

We focused in selecting four fungi, naturally living in Eucalyptus sp. fields, for application in accelerating stump decay. The wood-rot fungi Pycnoporus sanguineus (Ps), Lentinus bertieri (Lb) and Xylaria sp. (Xa) were isolated from Eucalyptus sp. field and the fungus Lentinula edodes (Led) was obtained from a commercial strain. All fungi were studied according to their capacity to degrade eucalyptus urograndis wood. In order to evaluate mass losses of seven years old eucalyptus urograndis' wood test blocks from heartwood were prepared added to glass flasks with red clay soil. The humidity of the soil was adjusted with 50 and 100% of its water retention capacity. Mass loss evaluations occurred at 30 until 120 days after eucalyptus wood degradation. Chemical analysis and soil pH were measured only in the last evaluation. Mycelial growth assays with potato-dextrose-agar, malt-agar and sawdust-dextrose-agar at three temperatures was carried out in order to get information about the best conditions of fungi growth. On the 120th day, Ps and Lb showed good capacity of wood degradation by leading to a high mass loss in soil with highest humidity. These fungi were the best consumers of lignin, hemicellulose, cellulose and extractives, caused acidification in the soil. Ps and Lb had faster mycelial growth in sawdust-dextrose-agar, especially in high temperature, comparing to Xa and Led. Xa and Led are not good eucalyptus urograndis heartwood degraders, because they consume preferentially hemicellulose.

Use of Activated Red Clay Soil from Kiteto District, Tanzania, as a Remedial Method for High Fluoride Levels in Drinking Water

The fluoride levels in the water samples were determined potentiometrically using a fluoride ion selective electrode. Different experiments on remediation of fluoride containing water with activated clay soil were carried out. Studies on effect of calcination temperature on activation of clay, minimum amount of calcinated clay soil giving optimum defluoridation, effect of contact time for optimal defluoridation and reusing activated soil for defluoridation of water were performed. The best activation temperature for the red clay soil from Kiteto District was found to be 700 °C. For best results, the clay should be heated at this temperature for 3 hours, allowed to cool then used. The optimum water defluoridation contact time was found to be 8 hours. It was established that for 100 mL of fluoridated water with 4.59 mg-F L-1, a minimum of 10 g of calcinated clay soil was required to reduce the concentration of fluoride ions to ≤1.1 mg-F L-1 which is well below the WHO recommended level of 1.5 mg-F L-1 for potable drinking water. The results also showed that the activated red clay soil can be repeatedly dried and re-used for the defluoridation process for a maximum of four times. It is recommended that the local red clay soil properly activated as described be used for the defluoridation of drinking water from Kiteto district, Tanzania. Investigation of possible usage of the activated clay soil for defluoridation of drinking water of other areas in the country is advocated.