Effect of variations in the redox potential of Gleysol on barium mobility and absorption in rice plants

Soil chemistry and meteorological conditions influence the elemental profiles of West European wines

Elemental profiles of wines have been used successfully to distinguish their geographical provenience around the world; however, underlying mechanisms are poorly understood. In this study, Ba, Ca, Mg, Mn and Sr contents were determined in 215 wines from several West European wine-growing areas using an easy-to-perform analysis based on ICP-OES. Major environmental and wine-making parameters (soil type as "calcareous" or not, rainfall, temperature and wine color) were used to explain variations within the dataset. The combined effects of wine-making processes (expressed by wine color) and soil type explained 28.5% of total variance. The effect of climatic conditions explained 24.1% of variance and could be interpreted as intensity of drought stress. Finally, carbonate occurrence in soils and climatic conditions systematically influenced the elemental composition of the wines. These findings provide insights into the mechanisms underlying elemental fingerprinting and allow prediction of which wine-growing regions can easily be distinguished based on elemental profiles as a marker of the terroir in viticulture.

Phytoremediation of barium-affected flooded soils using single and intercropping cultivation of aquatic macrophytes

Aquatic macrophytes are potentially useful for phytoremediation on flooded areas. A field study in Brazil was conducted to evaluate Eleocharis acutangula (E), Cyperus papyrus (C) and Typha domingensis (T) in monocropping and intercropping, aiming to phytoremediate barium-polluted flooded soils. The treatments were: monocroppings (E, C and T); double intercroppings (EC, ET and CT); and triple intercropping (ECT). The 180-d field trial was performed in a flooded area with high barium content, with a randomized complete block design and three replicates. Plant stand size, biomass yield, and Ba concentration aboveground/Ba concentration in roots (translocation factor - TF) as well as Ba mass aboveground/Ba mass in roots (mass translocation factor - mTF) were determined. Most of the treatments did not differ on dry biomass, except for EC, which showed the lowest yield. Consistently with its biology, E. acutangula in monocropping showed the largest plant stand. Otherwise, intercroppings with T. domingensis achieved the highest amounts of barium absorbed from the soil and transferred most of the barium content from belowground to aboveground (mTF > 1.0), especially ET, which showed the highest mTF among the intercroppings (2.03). Remarkably, TF values did not reflect such phytoextraction ability for CT and ECT. Thus, mTF was more appropriate than TF to assess phytoextraction capacity. Furthermore, it was demonstrated that intercropping can increase barium uptake from flooded soils. Particularly, the intercropping ET constituted the most cost-effective treatment, with the cyperaceous species providing high plant coverage while T. domingensis facilitated barium removal by translocating it to the aboveground biomass.

Selection of plants for phytoremediation of barium-polluted flooded soils

The use of barite (BaSO4) in drilling fluids for oil and gas activities makes barium a potential contaminant in case of spills onto flooded soils, where low redox conditions may increase barium sulfate solubility. In order to select plants able to remove barium in such scenarios, the following species were evaluated on barium phytoextraction capacity: Brachiaria arrecta, Cyperus papyrus, Eleocharis acutangula, E. interstincta, Nephrolepsis cf. rivularis, Oryza sativa IRGA 424, O. sativa BRS Tropical, Paspalum conspersum, and Typha domingensis. Plants were grown in pots and exposed to six barium concentrations: 0, 2.5, 5.0, 10.0, 30.0, and 65.0 mg kg^-1. To simulate flooding conditions, each pot was kept with a thin water film over the soil surface (∼1.0 cm). Plants were evaluated for biomass yield and barium removal. The highest amount of barium was observed in T. domingensis biomass, followed by C. papyrus. However, the latter exported most of the barium to the aerial part of the plant, especially at higher BaCl₂ doses, while the former accumulated barium preferentially in the roots. Thus, barium removal with C. papyrus could be achieved by simply harvesting aerial biomass. The high amounts of barium in T. domingensis and C. papyrus resulted from the combination of high barium concentration in plant tissues with high biomass production. These results make T. domingensis and C. papyrus potential candidates for phytoremediation schemes to remove barium from flooded soils.

Spatial variability and solubility of barium in a petroleum well-drilling waste disposal area

The petroleum industry generates a range of wastes which is often are disposed in soil close to the well location, negatively affecting soil and water quality. The objective of this study was to evaluate the solubility and map the spatial variability of barium in a potentially contaminated area. The study area consisted of a petroleum well-drilling waste disposal site located in the municipality of Mato Rico-PR. A large georeferenced sampling grid was organized. Soil samples were collected at depths of 30, 60, 90, and 120 cm for determination of the "pseudo-total" concentrations and geochemical fractionation of barium. The barium concentrations showed spatial dependence, which permitted the use of geostatistical interpolators. Regarding depth, the depth of 0-30 cm showed the largest contaminated area; however, higher concentrations of barium were found at the depth of 60-90 cm. The results of geochemical fractionation showed that the analyzed samples contained percentages higher than 99% in the non-labile fraction (residual). These results indicate clearly that the barium was in a condition of low solubility, even for samples that had the highest concentrations, presenting low-environmental risk.

Arsenic speciation and heavy metal distribution in polished rice grown in Guangdong Province, Southern China

Arsenic speciation and heavy metal distributions have been investigated in locally grown rice grains from Guangdong Province, Southern China. A total of 41 polished rice grain samples were collected throughout Guangdong Province. Arsenite (As(III)), as the predominant form found in the rice, was positively correlated (p<0.01) with total As (tAs) concentration. However, the percentage of As(III) reduced while tAs concentration increased (r=-0.361, p<0.05), due to restricted accumulation and translocation of As(III) in rice grains at high level of tAs. Statistical and geostatistical analyses were applied to investigate potential origins of heavy metals in rice. Only Cd, Cu and Ni were identified as influenced by anthropogenic sources such as industrial and commercial activities. As and Pb were primarily controlled by natural occurrence. The results of health risk assessment implied that continuous intake of rice grown in Guangdong Province could cause considerably non-carcinogenic and carcinogenic risk to local inhabitants.

The effects of oil well drill cuttings on soil and rice plant development (Oryza sativa) under two redox conditions

Few studies have focused on the release of toxic elements from oil well drill cuttings and their effect on soil. The present study evaluated these effects using rice growth as the endpoint. Drill cuttings were collected from a Brazilian well and added in doses of 300, 3,000 and 6,000 mg kg(-1) soil, which was maintained at oxidized or reduced conditions. When the redox potential reached approximately -250 mV, barium concentrations were determined by geochemical fractionation. Overall, doses of 300 and 3,000 mg kg(-1) promoted plant development, while a dose of 6,000 mg kg(-1) inhibited it due to the associated increase in electrical conductivity and exchangeable sodium concentration. In addition, the lower redox potential promoted solubilization of barite from the drill cuttings, which increased barium absorption by plants and translocation to grain, posing a risk to human health.