Interregional traceability of Tunisian olive oils to the provenance soil by multielemental fingerprinting and chemometrics

The aim of this study was to prove the usefulness of multielements as provenance markers of olive oils by evaluating their link with soil composition and their discriminatory power. Eleven elements in twenty-one olive oils and their paired soils from four Tunisian regions were characterized. Chemometrics have been implemented for ICP-MS data processing. Principal component analysis identified the predominant geochemical source of the elements in the oils based on their associations according to Goldschmidt’s rule. Although a clear correlation was not proven, correspondence was identified between the discriminating elements for both the soils and olive oils, which included Fe, Rb, Mg, and Pb. Linear discriminant analysis achieved classification and prediction rates of 92.1% and 87.3%, respectively. Our study substantiates the validity of multielements as markers of the olive oils’ provenance, and that an elemental fingerprinting approach can be successfully applied in the construction of a database of Tunisian olive oils

Attenuation of inorganic arsenic and cadmium in rice grains using by-product iron materials from the casting industry combined with different water management practices

<p>We examined the effect of two types of iron (Fe) material produced by the casting industry (spent steel shot [SSS] and residual iron material from steel shot production) on the mobility of arsenic (As) and cadmium (Cd) in soils. We also examined the uptake of these elements by rice plants (<i>Oryza Sativa</i> L.) under continuously flooded (CF) and water-saving (WS) cultivation. The application of both Fe materials (at 10 and 30 t ha^‒1) strictly limited As mobilization in soils under CF cultivation. As a result, As uptake by rice plants declined, along with the total and inorganic As (iAs) concentration in rice grains. In comparison, As immobilization caused by the application of Fe material was less clear under WS cultivation. The rate of Fe material application was negatively correlated with As uptake by rice plants. It was also negatively correlated with total and iAs concentration in rice grains under both water management practices. The combination of applying Fe materials and WS cultivation decreased iAs concentration in rice grains to approximately one-fifth of that in rice grains produced from plants grown on soils without Fe material application under CF cultivation. CF cultivation strictly decreased dissolved Cd in soils, as well as Cd in rice grains with and without Fe material application. The application of Fe materials decreased Cd mobility and, hence, Cd uptake in rice plants, ultimately reducing the accumulation of Cd in rice grains under WS cultivation. Residual Fe material had a statistically greater effect at attenuating Cd accumulation in rice grains than SSS. The present study demonstrated the potential of combining by-product Fe material application and water management practices to attenuate iAs and/or Cd concentrations in rice grains. Practical countermeasures should be carefully adopted that consider the existing risks of iAs and Cd on each paddy field, and the combined effect of Fe material application and water management practices.</p

Arsenic immobilization in anaerobic soils by the application of by-product iron materials obtained from the casting industry

<p>Reducing the arsenic (As) concentration in rice grains is of great interest from a human health perspective. Iron (Fe) materials immobilize As in soils, thereby effectively reducing the As concentration in rice grains. We investigated the effect of by-product Fe materials obtained from the casting industry on the As mobility in two soils (soil A and soil B) by a long-term (approximately 100 days) flooded soil incubation experiment. The examined Fe materials were spent steel shot (SSS), fine spent casting sand (SCS) containing steel shot, and two kinds of residual Fe materials (RIMs) from steel shot production. Commercial Fe materials used to immobilize As (zero-valent Fe and ferrihydrite) were tested for comparison. The dissolved As in soil solution of controls for soil A and soil B reached approximately 100 and 800 μg L^‒1, respectively. The effect on As immobilization of all the by-product Fe materials increased with time and was comparable to or greater than that of commercial ferrihydrite, except for SCS. The additions of SSS and RIMs decreased by more than 90% of the dissolved As in soil A and decreased by more than 50% in soil B after 100 days incubation. Overall, the effect of the by-product Fe materials on the solubility of silicon and phosphorus was much less than that of the commercial Fe materials. Considering the cost advantage over commercial Fe materials, the Fe materials obtained from the casting industry as by-products are promising amendments for the immobilization of As in paddy soils.</p

Microscale Heterogeneous Distribution and Speciation of Phosphorus in Soils Amended with Mineral Fertilizer and Cattle Manure Compost

Global concerns for the sustainability of agriculture have emphasized the need to reduce the use of mineral fertilizer. Although phosphorus (P) is accumulated in farmland soils due to the long-term application of fertilizer, most soil P is not readily available to plants. The chemical speciation of P in soils, which comprise heterogeneous microenvironments, cannot be evaluated with a high degree of specificity using only macroscopic analyses. In this study, we investigated the distribution and speciation of P accumulated in soils by using both macro- and microscopic techniques including chemical extraction, solution and solid-state 31P NMR, bulk- and micro- P K-edge X-ray absorption near edge structure (XANES), and electron probe microanalysis (EPMA). Soil samples were collected from a field in which cabbage was cultivated under three amendment treatments: i) mineral fertilizer (NPK), ii) mineral fertilizer and compost (NPK + compost), and iii) mineral fertilizer plus compost but without nitrogen fertilizer (PK + compost). Macro-scale analyses suggested that accumulated P was predominantly inorganic P and associated with Al-bearing minerals. The repeated application of compost to the soils increased the proportion of P associated with Ca which accounted for 17% in the NPK + compost plot and 40% in the PK + compost plot. At the microscale, hot spots of P were heterogeneously distributed, and P was associated with Fe and Ca in hot spots of the NPK + compost (pH 6) and PK + compost (pH 7) treated samples, respectively. Our results indicate that application of compost contributed to creating diverse microenvironments hosting P in these soils

Simultaneous decrease of arsenic and cadmium in rice (<i>Oryza sativa</i> L.) plants cultivated under submerged field conditions by the application of iron-bearing materials

<p>The Codex Alimentarius Commission has recently adopted maximum levels for inorganic arsenic (As; in 2014) and total cadmium (Cd; in 2006) in polished rice grains to maintain food safety and to decrease the risk to human health. As rice is a staple crop in Japan and monsoon Asian countries, reducing concentrations of As and Cd in rice is an urgent matter. In flooded conditions, Cd concentration in soil solution decreases whereas As concentration increases. Therefore, we aimed to evaluate the efficiency of iron-bearing materials to decrease As concentration in soil solution and rice (<i>Oryza sativa</i> L.) grain under submerged cultivation, while also considering Cd concentration. In experiments conducted in paddy fields in six regions, As concentrations in the soil solution during the cultivation period decreased in the following order: control (REF) > steel converter furnace slag (SCS) > non-crystalline iron hydroxide (FH) > zero-valent iron (ZVI). The concentrations of As in brown rice were in the same order, with ZVI achieving particularly strong reduction. Cadmium concentrations were low, probably owing to submerged cultivation conditions. Application of iron-bearing materials slightly and insignificantly reduced the yields of brown rice and straw. Application of these materials did not have a significant negative impact on the quality of rice. Our data indicate that the application of iron-bearing materials effectively reduces As concentrations in soil solution and rice grains without negative effects on yield and quality, with a particularly powerful effect of ZVI which is possibly explained by arsenic sulfide formation.</p