Addition Of Bentonite Research Articles

Exploring necessity to pre-treat organic fraction of waste prior to use in an earthen MFC modified with bentonite.

In this study, the addition of bentonite at different proportions as clay minerals and various thicknesses (4, 5, and 6 mm) of ceramic membranes were evaluated for proton and oxygen mass transfer coefficients. Bentonite (20% and 4 mm) was found to be optimum and was then employed to assess earthen microbial fuel cell (EMFC) performance for different substrates (kitchen waste (KW) slurry and leachate) under batch mode. Both substrates were added in different concentrations of chemical oxygen demand (COD), i.e., 18, 15.2, 12.5, 9.7, and 6.9 g/L to EMFCs. The EMFC achieved superior organic removals for leachate (>96%). Intriguingly, the volatile fatty acids (VFAs) generation and consumption were different for each substrate. Each system expressed affinity towards acetic acid, but limited VFAs (acetic and propionic) were generated by KW while leachate generated acetic, propionic, and butyric. The leachate concentration having COD of 15.2 g/L produced the highest power density of 586.5 ± 38.8 mW/m3, while for KW, only 41.5 mW/m3 (6.9 g/L of COD for KW) was obtained. The study consolidates the need for an intermediate step to pre-treat the organic fraction of waste before its use for resource recovery. Bentonite was found as an effective clay mineral for manufacturing ceramic membranes.

Manufacturing of Fluff Pulp Using Different Pulp Sources and Bentonite on an Industrial Scale for Absorbent Hygienic Products

In this study, for the first time, a composite fluff pulp was produced based on the combination of softwood (i.e., long-length fiber), hardwood (i.e., short-length fiber), non-wooden pulps (i.e., bagasse) and bentonite, with specific amounts to be used in hygienic pads (e.g., baby diapers and sanitary napkins). After the defibration process, the manufactured fluff pulp was placed as an absorbent mass in diapers and sanitary napkins. Therefore, tests related to the fluff pulp, such as grammage, thickness, density, ash content, humidity percentage, pH and brightness, tests related to the manufactured baby diapers, such as absorption capacity, retention rate, retention capacity, absorption time and rewet, and tests related to the sanitary napkin, such as absorption capacity and rewet, were performed according to the related standards. The results demonstrated that increasing the amount of bagasse pulp led to increasing the ash content, pH and density of fluff pulp and decreasing the brightness. The addition of bentonite as a filler also increased ash content and pH of fluff pulp. The results also demonstrated that increasing of bagasse pulp up to 30% in combination with softwood pulp led to increasing absorption capacity, retention rate, retention capacity, absorption time and rewet of baby diapers and of sanitary napkins.

Investigation of the properties of alkaline binding materials with the addition of fine bentonite

Introduction. Searching for new methods of making less energy-intensive materials by reducing their cost, adding local raw materials and industrial waste to the mineral resource base, as well as developing efficient production technologies is a relevant problem of the construction industry. A clinker-free technology for the manufacture of hydraulic binders will partially replace resource-intensive Portland cement in construction and help to solve these problematic issues to a certain extent and boost the environmental safety at the global level. The proposed binders, based on principles of structurization in alkaline systems as a combination of sequential and parallel physical and chemical transformations due to the contact interaction between fine powders of aluminosilicate nature and cations of alkali metals, contribute to the formation of strong and durable composites.
 Materials and methods. The study of energy dispersive microanalysis of components of the binder system was performed using the QUANTA 3D scanning electron microscope; dynamic light scattering was employed to study the particle granulometry with the help of the HORIBA analyzer. The strength characteristics of the binder systems “aspiration dust – bentonite – Na2O∙SiO2” were determined according to GOST 30744-2001 using Testometric FS150AT testing machine.
 Results. Electron microscopic analysis showed that particles of aspiration dust larger than 200 microns and smaller than 100 microns have a similar oxide composition, with a predominance of oxides of calcium, silicon, aluminum and carbon. The chemical composition of bentonite confirms the aluminosilicate nature. An increase in the physical and mechanical properties of specimens of the systems “aspiration dust – bentonite – Na2O∙SiO2” has been identified; it is the addition of higher dispersion bentonite that contributes to the dense packing of grains due to the volume-wise redistribution of particles, which positively affects the pore structure and water resistance of the cement stone.
 Conclusions. The results of the study have proven the new prospects for the alkaline activation of complex powders made of cement industry waste and bentonite clay; the characteristics and dependencies, obtained by the authors, will allow using the proposed technology in construction.

Direct Shear Strength Characteristics in Unsaturated Compacted Soil Surface Coverage on Pb(II)-Polluted Tailings Reservoir under Low Normal Stress

Mining activities generate a large amount of solid waste called tailings, and it often contains a certain number of heavy metals, depending on the different types of minerals. To avoid disasters caused by the diffusion of tailings and their infiltration into surface water, mines often use tailings ponds as a surface coverage structure. This study mainly focused on the shear strength of surface coverage isolation layer soil under low normal stress. The soil isolation layers with different values of dry bulk density, water content, bentonite content, and Pb(II) ion concentration were treated with direct shear strength under normal stress at 12.5, 25, 50, and 100 kPa. It was found that when the dry bulk density was increased from 1.1 g/cm3 to 1.3 g/cm3, the shear strength increased by 49.3%~117.2%, and when the water content was decreased from 24% to 16%, the shear strength increased by one to three times. With the addition of bentonite in proportions from 18% to 30%, shear strength increased by 1.9 to 116.9 kPa, and the degree of improvement was related to both dry bulk density and water content; the specimens with bentonite added were more sensitive to Pb(II) ion concentration, and when the specimen with 24% bentonite addition was compared with the specimen without the addition of bentonite, both under a Pb(II) ion concentration of 5 mg/L, the shear strength decreased by 8.1~35.6 kPa, the internal friction angle decreased by 0.5~9.7°, the cohesion force decreased by 5.8~37.7 kPa, and the shear modulus decreased by 5~12 kPa/mm. Therefore, in order to maintain good mechanical properties in the surface covering structure, it is necessary to maintain a high dry bulk density, low water content, and bentonite content of no less than 24%.

Mechanical and durability performance of concrete mixtures incorporating bentonite, silica fume, and polypropylene fibers

Cement demand has steadily increased around the world, negatively impacting the environment by consuming a substantial amount of energy, depleting raw materials, and contributing to climate change. Supplementary cementitious materials (SCMs) can be a potential way to deal with environmental issues by providing an alternative to the cement industry, resulting in more efficient, sustainable, and long-lasting concrete while keeping the environment safe for subsequent generations. The effect of individual and combined integration of bentonite and silica fume as a partial replacement for cement in concrete mixes with polypropylene fibers (PPF) was investigated by determining the mechanical and durability properties of concrete mixes. Binary mixes, containing either bentonite or silica fume as a partial replacement of cement, were prepared along with ternary mix incorporating both the SCMs. Additionally, PPFs were added to the ternary blends in increments of 0.25%, resulting in nine distinct concrete mixtures. Compressive, splitting tensile and flexural strength tests were carried out to study the hardened concrete properties. UPV, sorptivity, porosity, water permeability, abrasion resistance, acid attack resistance, and chloride penetration tests were performed to examine the durability properties. The experimental results exhibited that the addition of silica fume and bentonite resulted in enhanced compressive, splitting tensile and flexural strengths. The durability properties of SCM concrete mixtures also improved compared to the control mix. The microstructure investigation depicted a denser concrete in the case of SCM incorporated mixes. PPF mixes showed satisfactory performance up to a certain percentage of PPF (i.e., 0.5%).

Adsorption of Rhodamine B from Simulated Waste Water onto Kaolin-Bentonite Composites.

Organic dye rhodamine B is one of the common organic pollutants in the water and soil environment. This study investigated the feasibility of removing rhodamine B from an aqueous solution through adsorption by kaolin, kaolin-sodium bentonite, and kaolin-organic bentonite. Batch adsorption test results showed that the maximum adsorption quantities of kaolin, kaolin-sodium bentonite, and kaolin-organic bentonite were 7.76 mg/g, 11.26 mg/g, and 12.68 mg/g, respectively, implying that the addition of bentonite to kaolin can effectively improve its adsorption capacity for rhodamine B. Moreover, the Langmuir isotherm model is suitable to describe the adsorption of rhodamine B by kaolin and kaolin-sodium bentonite, while it is preferable to use the Freundlich isotherm model in the case of kaolin-organic bentonite. The adsorption kinetic characteristics of rhodamine B, by these three adsorbents, are suitable to be described with a pseudo-second order kinetic model. Furthermore, the characteristics of the above three adsorbents were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The above results indicated that kaolin and organic bentonite can be used to design efficient adsorbents for organic pollutants similar to rhodamine B.

MoS2/Bentonite prepared by a facile method for efficient removal of Cd2+ from aqueous solution

The pollution of heavy metals in aqueous solution has been paid considerable attention in the past several decades. Many researches focused on developing new materials or methods for removing heavy metals. The two-dimensional lamellar structure of molybdenum disulfide (MoS 2 ) has attracted extensive interest and was regarded as a potential material due to it has a large number of active sites. In this paper, a novel one-step hydrothermal method was proposed to prepare the MoS 2 /Bentonite composite material. The MoS 2 composed of many nano petals grew successfully in the pores of bentonite to form flower spheres, and the addition of bentonite can effectively avoid the agglomeration phenomenon of MoS 2 prepared by the hydrothermal method. Pseudo-second-order model was applied to describe the adsorption process, revealing the adsorption dominated by chemical adsorption. The dynamic model was in accord with the Langmuir model and the maximum adsorption capacity of Cd 2+ was 89.45 mg/g. The excellent performance of MoS 2 /Bentonite made it have the tremendous application of removing heavy metal ions. • MoS 2 /Bentonite was prepared by a facile one-step hydrothermal method. • The addition of bentonite can avoid the agglomeration phenomenon of MoS 2 . • The performance of MoS 2 /Bentonite was superior to both pure MoS 2 and bentonite. • The adsorption characteristics were analyzed by kinetic model and isotherm model. • MoS 2 /Bentonite exhibited considerable adsorption capacity of Cd 2+ from water.

Development of Cationic Cellulose-Modified Bentonite-Alginate Nanocomposite Gels for Sustained Release of Alachlor.

The nanocomposite gel prepared from nanoclay and natural polysaccharides showed a good sustained-release property. Herein, a cationic cellulose-modified bentonite–alginate nanocomposite gel was prepared and used to enhance the sustained release of alachlor. The underlying effect and mechanism of the structure of modified bentonite–alginate nanocomposite gels on the release behavior of alachlor were explored by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric (TG) analysis. The results showed that the release of alachlor from the nanocomposite gels was dominated by Fickian diffusion and closely related to the adsorption capacity and permeability of the matrix. The cationic cellulose intercalated into the interlayer space of bentonite through an ion exchange reaction, which significantly enhanced the hydrophobicity of bentonite and its interaction with alachlor. The stacking aggregation of bentonite nanoplatelets and permeability of the gel network were decreased through the electrostatic interaction between cationic cellulose and alginate molecular chains, thus remarkably enhancing the sustained-release property of the nanocomposite gel. The release kinetics revealed that the release rate of alachlor from the nanocomposite gel first decreased and then increased as the content of bentonite and modified bentonite gradually increased. Also, the best sustained-release property of the nanocomposite gel was obtained at bentonite and modified bentonite additions of about 10%, under which the release time of 50% alachlor (T50) from bentonite–alginate and modified bentonite–alginate nanocomposite gels was 4.4 and 5.6 times longer than the release time from pure alginate gels, respectively.

Effects of Green Oaks Acorns (Quercus ilex) based Diets Added of Calcium Bentonite on Health of Broilers Reared in the Cages and Ground Modes

Background: The use of natural resources and food additives rich in bioactive nutrients in poultry diets offer better digestive use and have a proven health impact. In this context, the use of green oak acorn added of calcium bentonite are better suited to to improve growth and enrich the meat with a some its nutrients limit the meat lipoperoxidation. In addition, the breeding battery mode compared to the ground mode offers better conditions and enhance productivity. This study evaluated the effects of diets based on green oak acorns supplemented with calcium bentonite on organ histology of broilers to ascertain the impact on the poultry health. Methods: 300 broilers one day-old of the ISA F15 strain were divided into two groups, one raised on the ground and the other in cages. Each group was divided into three subgroups. Each subgroup receives either a standard diet without addition of acorn or bentonite constituting the diet control (DC). Result: Analysis of the histological sections revealed that the addition of bentonite in the feed of poultry reared, particularly on the ground seems to preserve at the best histological level of certain internal organs; Fabricius bursa, liver, small intestines. Adding bentonite to the acorn diet nearly halved the intensity of follicular necrosis compared to the lesion appearance of controls. Follicular scarring expressed by the extent of fibrosis was extensive on the bursae. This study concluded that the use of green oak acorn in chicken feed along with 2% calcium bentonite shows the best beneficial effects on health status.

Influence of Clay Mineral Amendments Characteristics on Heavy Metals Uptake in Vetiver Grass (Chrysopogon zizanioides L. Roberty) and Indian Mustard (Brassica juncea L. Czern)

Phytoremediation is limited when heavy metals reduce soil quality and, subsequently, inhibit plant growth. In this study, we evaluated the use of attapulgite and bentonite as amendments in soil contaminated with multiple metals, to improve the phytoremediation capacity of Vetiver grass and Indian mustard. A 21-day greenhouse study was undertaken, to investigate plant tolerance in heavy-metal-contaminated soil, as well as heavy-metal absorption in plant roots and shoots. The results showed a generally higher root-uptake rate for Cr, Cu, Co, Ni, and Zn in Vetiver grass. Overall, the highest absorption for Ni, Cr, Co, Cu, and Zn was 1.37, 2.79, 1.39, 2.48 and 3.51 mg/kg, respectively, in the roots of Vetiver grass. Clay minerals inhibited the translocation of some heavy metals. The addition of attapulgite improved the phytoremediation capacity of Vetiver for Ni, Cr, and Co, while bentonite improved Vetiver’s absorption of Cu and Zn. The translocation factor for Ni in one of the attapulgite treatments was 2, indicating that attapulgite improved the phytoextraction of Ni by Vetiver grass. Our results confirm that attapulgite at 2.5% (w/w) can successfully improve the phytostabilization of heavy metals by Vetiver grass. Indian mustard showed no significant metal uptake that could be detected by inductively coupled plasma optical emission spectrometry (ICP-OES), despite the addition of attapulgite and bentonite. This research contributes to the knowledge repository of suitable amendments that improve the phytoremediation properties of Vetiver grass.

Tensile Strength of Class F Fly Ash and Fly Ash with Bentonite Addition as a Material for Earth Structures.

The behavior of soils under tensile stress is of interest to geotechnical engineers. Tensile strength of soils is often associated with tensile fractures that can generate a privileged flow path. The addition of bentonite improves the plastic properties of the soil, therefore the study was conducted for the compacted class F fly ash and fly ash with various bentonite additions. An amount of bentonite was: 5, 10 and 15%, calculated in weight relation to dry mass of samples. The tensile strength of compacted clay was also established, for comparison. Laboratory tests were carried out using the direct method (breaking) on cylindrical samples and the indirect method (the Brazilian test) on disc-shaped specimens. For this purpose, a universal testing machine with a frame load range of ±1 kN was used. It is stated that bentonite considerably influences the tensile strength of the fly ash evaluated with both methods. The tensile strength values obtained with the Brazilian method are comparable or higher than those obtained with the direct method. The achieved tensile strength values of compacted fly ash, improved by 10−15% of bentonite addition, are comparable with the results obtained for clay used in mineral sealing, while the strain at maximum tensile strength is similar in the direct test and lower in the indirect test.

The Addition of Different Adsorbents In SA-PVA Matrix For Bacillus Subtilis Immobilization on Methylene Blue Decolorization

Wastewater which is not handled by a proper treatment before released in the water body, can cause damage for aquatic biota and its environment. MB is a synthetic textile dye which is toxic and difficult to degrade. Bioremediation by decolorization using microbes such as bacteria is one of the best methods for dye removal. By immobilizing Bacillus subtilis bacterium in an appropriate matrix, it could have more advantage on dye decolorization than by free cell only. The sodium alginate (SA) and polyvinyl alcohol (PVA) are well known as good matrix for decolorization. Besides the addition of B. subtilis in the SA-PVA matrix, the addition of adsorbents could enhance the decolorization. In this study, different adsorbents: bentonite, activated charcoal, kaolin, and corncob powder were investigated for influencing MB decolorization by immobilized B. subtilis in SA-PVA matrix. The result showed that the highest MB decolorization was reached by SA-PVA-B. subtilis with the presence of activated charcoal by approximately 88% of 100 mg/L, followed by the addition of bentonite (82%), kaolin (80%), and corncob powder (79%). The MB decolorization by SA-PVA-Activated charcoal-B. subtilis reached optimum condition at temperature 35 °C, 24 h incubation time in static condition.

Experimental Study on Mineral Phase Structure and Metallurgical Properties of Pellets

Pellet is an important part of raw materials for blast furnace. The quality of the pellet directly affects the quality of molten iron. The mineral composition and microstructure of pellets are important factors affecting their metallurgical properties. In order to improve the metallurgical properties of the pellets, this experiment studied the influence of the addition of bentonite and the calcination temperature on the mineral phase structure of the pellets.

Study of Desiccation Crack Behavior of Fly Ash - Bentonite (FAB) Composite in Landfill Liner System

The addition of bentonite to fly ash can lower the permeability coefficient of the composite landfill liner. Also, the montmorillonite bentonite can bind quite a lot of water molecules during the hydration process. In this study, the effect of mixture, water content, and salinity on the desiccation cracking phenomenon in the bentonite - fly ash mixture as a landfill liner system was investigated by conducting tests such as desiccation test, water content test, and standard proctor and permeability test. The variation in bentonite levels: 0%, 15%, 20%,25% and 25% + 1 N NH4Cl solution. The result shows that the appropriate mixture is fly ash + 15% bentonite with permeability of 4,065 x 10-7. The mixture complies with local regulations where the permeability coefficient of the bottom layer of the landfill should be less than 10–6 cm/s and have a low cracking value (CIF). Furthermore, the addition of saline solution to the composite can rise the value of the optimum moisture content. However, saline conditions can decrease the value of CIF drastically

An Investigation of the Effects of Additives and Burning Temperature on the Properties of Products Based on Loam

This study aimed to identify the composition of ceramic mass for the manufacture of bricks with improved properties based on local loam using diatomite and bentonite clay. For the experiments, loam from the Almaty deposit (Kazakhstan) was applied as the primary product, and used for the production of ceramic bricks with grades of 75 and 100. Diatomite from the Zhalpak and Utesai deposits and highly plastic bentonite clay from the Darbazin deposit (Kazakhstan) were used as additives. An analysis of the properties of the burned products demonstrated that supplementation with diatomite and bentonite in the loam lowers the average density and increases the compressive strength of samples burned at 1000 and 1100 °C. Herewith, the optimal amount of diatomite and bentonite clay to add is 15%, with a fractional composition of 0.315–0.16 mm and less than 1 mm, respectively. It was established that the optimal additions of diatomite and bentonite clay to loam make it possible to obtain after burning at 1170 °C samples of ceramic products corresponding to the 2nd class in terms of the average density and compressive strength grades M 400 and M 500.

Combined remediation mechanism of bentonite and submerged plants on lake sediments by DGT technique

The diffusive gradients in thin films (DGT) technique was applied to determine the mechanism by which bentonite improves the eutrophic lake sediment microenvironment and enhances submerged plant growth. The migration dynamics of N, P, S, and other nutrient elements were established for each sediment layer and the remediation effects of bentonite and submerged plants on sediments were evaluated. Submerged plant growth in the bentonite group was superior to that of the Control. At harvest time, the growth of Vallisneria spiralis and Hydrilla verticillata was optimal on a substrate consisting of five parts eutrophic lake sediment to one part modified bentonite (MB5/1). Bentonite addition to the sediment was conducive to rhizosphere microorganism proliferation. Microbial abundance was highest under the MB5/1 treatment whilst microbial diversity was highest under the RB1/1 (equal parts raw bentonite and eutrophic lake sediment) treatment. Bentonite addition to the sediment may facilitate the transformation of nutrients to bioavailable states. The TP content of the bentonite treatment was 22.47%–46.70% lower than that of the Control. Nevertheless, the bentonite treatment had higher bioavailable phosphorus (BIP) content than the control. The results of this study provide theoretical and empirical references for the use of a combination of modified bentonite and submerged plants to remediate eutrophic lake sediment microenvironments.

English

Aflatoxin in poultry feed reduces production, and is a health hazard to the consumers. Its toxicity is reduced through addition of clays. Evaluation of the country’s bentonites may promote their use as toxin binder. After detailed mineralogical and aflatoxin adsorption characteristics of large number of indigenous quarries effectiveness of two bentonites was determined through feeding trial. Bentonites from Bhimber and Dina quarries were applied in three replications at 1 and 2% (w/w) with positive and negative controls to a feed containing 250 μg kg-1 aflatoxin B1. Ten birds initially fed on clean starter feed for two weeks, fed on the experimental feeds and slaughtered after recording live weight on day 35 and dress weight along with internal organs weight were recorded with any apparent disorders. While addition of the bentonites had no detrimental effect, aflatoxin contamination had the lowest body weight and weight gain rate, reduced feed intake and feed conversion ratio with apparent disordered liver. The live body weight and weight gain rate increased with 2% bentonite addition to the contaminated feed from both the sources and was statistically similar to the clean feed though the values for these parameters were highest when the addition was to the clean feed. A 42% reduction occurred in weight gain without smectite addition in the toxin feed. The toxin feed had the lowest absolute liver and heart weight with dark coloration. The bentonites use in feed industry may reduce aflatoxin incidences at the application rate of 2%. © 2021 Friends Science Publishers

Experimental Investigation of Synchronous Grouting Material Prepared with Different Mineral Admixtures.

Waste sediment generated during tunnel construction is applied to prepare synchronous grouting material, where the influences of fly ash, slag powder, and bentonite on the rheological properties (such as consistency, fluidity, setting time, drainage rate, and stone rate) are studied. The results show that adding fly ash content increases the initial consistency, setting time, and fluidity of grouting material, but also increases its drainage rate and decreases its stone rate. The addition of slag powder results in a slight increase in the setting time and fluidity of the grouting material, yet a decrease in the initial consistency value. In contrast, with the addition of bentonite, both the initial consistency and fluidity of the grouting material decrease. Finally, the optimal mix ratio of high-performance and low-cost grouting materials is fixed to be 30% fly ash, 50% slag powder, and 10% bentonite. Therefore, the fluidity of grouting material can be 170 mm, with an initial consistency of 122 mm, setting time of 1050 min, stone rate of 96.2%, drainage rate of 1.5%, and 28-day compressive strength of 8.3 MPa.

Intensification of yam-starch based biodegradable bioplastic film with bentonite for food packaging application

Bioplastics are gaining more attention over synthetic plastics owing to their non-hazardous properties. Earlier studies had reported the biodegradation and solubility properties of yam starch-based bioplastic; however, its mechanical properties with reinforcement were not studied. The present work focuses on the development of yam ( Dioscorea ) starch-based bioplastic film with glycerol as a plasticizer. Different concentrations of bentonite (0.5, 1, 1.5 %w/w) was reinforced and the biofilms were prepared by solvent casting method. The developed bioplastic films were systematically characterized using the scanning electron microscope (SEM), Fourier transforms infrared spectroscopy (FTIR), contact angle, tensile testing, soil and water degradation, water vapor transmission rate (WVTR), swelling, solubility, and chemical testing. The SEM micrographs show the bentonite particles were homogeneously distributed in the starch matrix. The hydrophilicity of the bioplastic was increased with the addition of bentonite. The FTIR spectra revealed that the addition of bentonite in the bioplastic film strengthened the O–H bond and Si–O–Si bond, which improved the mechanical strength. It was observed that 1.5% bentonite concentration exhibited maximum soil degradation rate and lowest water molecule absorption. This is due to the intercalated silicate layer of bentonite in the bioplastic films. Also, the bioplastic films with bentonite were more impermeable in salt and acidic medium but remained ineffective in the basic medium. The study revealed that bentonite concentration has effectively improved the yam starch-based bioplastic property, making it a potential bioplastic to replace synthetic plastic in food packaging applications. • Yam starch with bentonite has improved the tensile strength of bioplastic films. • The B3 bioplastic film demonstrates the maximum soil degradation rate. • The lowermost absorption of water molecules was observed for B3 bioplastic film. • The Yam starch-based bioplastic can be utilized as a food packaging material.

Strontium Isotope Systematics of Tenerife Wines (Canary Islands): Tracing Provenance in Ocean Island Terroir

The production of fraudulent goods remains widespread and economically damaging. The high value of the wine industry makes it particularly vulnerable, and a number of geochemical methods have been developed to ensure traceability and identification of origin. Here, strontium (Sr) isotope data on wines from five defined regions in Tenerife (Canary Islands, Spain) show that the young volcanic geology imparts a clearly identifiable low 87Sr/86Sr signature (<0.7072). These values discriminate Tenerife wines from mainland Spanish and continental European produce, as these are much more radiogenic in general. However, unlike continental wine regions, wines from Tenerife show small but ubiquitous enrichments in 87Sr/86Sr above what is expected in the soils. Bentonite addition has not affected the 87Sr/86Sr signatures, with white wines at lower Sr concentrations than red wines in all regions. A number of natural contributions to the terroir are evaluated in relation to Tenerife’s unique combination of geology and geography. Atmospheric precipitation (rainfall) is likely a dominant influence on Sr isotope systematics in northern Denominación de Origen regions, and evaporation may play a role in buffering signatures in southern regions. Other natural additions of 87Sr are not precluded at a local scale, given the large range in climatic conditions of island terroir and known input of mineral dust from Africa. Despite natural explanations affecting the overall small shift observed, there are clear outliers with considerably higher 87Sr/86Sr and Sr concentration. This confirms the utility of Sr isotope systematics for oceanic-island viticulture and demonstrates the use of young volcanic soils for tracing natural inputs that may be masked in other regions.