Arsenic accumulation and speciation in strawberry plants exposed to inorganic arsenic enriched irrigation

Toxicity, arsenic speciation and characteristics of hyphenated techniques used for arsenic determination in vegetables. A review

Arsenic (As) speciation is an interesting topic because it is well recognized that the toxicity of this metalloid ultimately depends on its chemical form. More than 300 arsenicals exist naturally. However, As can be present in four oxidation states: As-III, As0, AsIII and AsV. Long-term exposure to As from different sources, such as anthropogenic processes, or water, fauna and flora contaminated with As, has put human health at risk for decades. There are many side-effects correlated with exposure to InAs species, such as skin problems, respiratory diseases, kidney problems, cardiovascular diseases and even cancer. There are different levels and types of As in foods, particularly in vegetables. Furthermore, different chemical methods and techniques have been developed. Therefore, this review focuses on the general properties of various approaches used to identify As species in vegetation samples published worldwide. This includes various approaches (different solvents and techniques) used to extract As species from the matrix. Then, versatile chromatographic and non-chromatographic systems to separate different forms of As are reviewed. Finally, the general properties of the most common instruments used to detect As species from samples of interest are listed.

The Level of Heavy Metal in Fresh and Processed Fruits: A Study Meta-analysis, Systematic Review, and Health Risk Assessment

Intake of fruits is important for health. However, it can be a contamination source of potentially toxic elements (PTEs). The present study aimed to investigate the concentration of PTEs such as arsenic (As), lead (Pb), cadmium (Cd), copper (Cu), nickel (Ni), and Iron (Fe) in various fresh and processed fruits. All the studies related to the concentration of PTEs in fresh and processed fruits by international databases including were included and non-carcinogenic risks assessment was evaluated based on the total hazard quotient (TTHQ). According to findings highest concentrations of As, Cd and Pb were observed in pineapple, mango, and cherry, while the lowest concentrations of these metals were found in berries, pineapple, and berries. Regarding trace elements, peach and cucumber represented the highest and lowest concentrations of Fe, respectively. Moreover, the highest and lowest concentrations of Cu were related to plum and banana, respectively. Considering the type of continents, the highest concentrations of As, Cd, Pb, Fe, Ni, and Cu among fresh and processed fruits belonged to Pan American Health Organization (EMRO), EMRO, African Region (AFRO), European Region (EURO), AFRO, and Western Pacific Region (SEARO). Eventually, the non-carcinogenic risk assessment of the heavy metal in fresh and processed fruits indicated that the risk pattern was different in various countries and the calculated TTHQ level in infants was below 1. Overall, the consumption of fresh and processed fruits is safe and does not pose a risk to the health of consumers.

Mobilization of arsenic from As-containing iron minerals under irrigation: Effects of exogenous substances, redox condition, and intermittent flow

Irrigation activities can cause strong geochemical and hydrological fluctuations in the unsaturated zone, and affect arsenic (As) migration and transformation. The As geochemical cycle in the unsaturated zone is coupled with that of iron minerals through sorption-desorption, coprecipitation and redox processes. Dynamic batch experiments and wetting-drying cycling column experiments were conducted to evaluate As mobilization behaviors under the effects of exogenous substances, redox condition and intermittent flow. Our results show that As release under exogenous substances carried by irrigation (e.g., phosphate, carbonate, fulvic acid, humic acid, etc.) followed three trends with the types of exogenous inputs. Inorganic anions and organic matter resulted in opposite trends of arsenate release in different redox conditions. In anoxic environments, As(V) release was favored by the addition of phosphate and carbonate, while in oxic environments, the mobilization of As(V) was promoted by the addition of fulvic acid (FA). Further, intermittent irrigation promoted the reductive dissolution of Fe oxides and the mobilization of As. The addition of humic acid (HA) resulted in the mobilization of arsenate as As-Fe-HA ternary complexes. The mechanism of arsenic mobilization under irrigation has importance for prevention of arsenic exposure through soil to food chain transfer in typical high arsenic farmland.

Arsenic acquisition, toxicity and tolerance in plants - From physiology to remediation: A review

Globally, environmental contamination by potentially noxious metalloids like arsenic is becoming a critical concern to the living organisms. Arsenic is a non-essential metalloid for plants and can be acclimatised in plants to toxic levels. Arsenic acquisition by plants poses serious health risks in human due to its entry in the food chain. High arsenic regimes disturb plant water relations, promote the generation of reactive oxygen species (ROS) and induce oxidative outburst in plants. This review evidences a conceivable tie-up among arsenic levels, speciation, its availability, uptake, acquisition, transport, phytotoxicity and arsenic detoxification in plants. The role of different antioxidant enzymes to confer plant tolerance towards the enhanced arsenic distress has also been summed up. Additionally, the mechanisms involved in the modulation of different genes coupled with arsenic tolerance have been thoroughly discussed. This review is intended to present an overview to rationalise the contemporary progressions on the recent advances in phytoremediation approaches to overcome ecosystem contamination by arsenic.

Persistent arsenate-iron(iii) oxyhydroxide-organic matter nanoaggregates observed in coal

Understanding how natural nanoaggregates of iron (Fe) and organic matter (OM), currently identified in organic rich soil or peat, interact with metals and metalloids is environmentally significant. Coal is also organic-rich and exemplifies anoxic sedimentary environments with Fe usually as pyrite and not oxides. Here, we analyze the local structure of Fe (6880-21 700 mg kg^-1) and As (45-5680 mg kg^-1) in representative Guizhou coal samples using X-ray absorption near-edge structure and extended X-ray absorption fine structure (XANES and EXAFS) to illustrate how Fe(iii) and As(v) are preserved in coal formed from reduced, organic-rich precursors. Arsenic XANES indicates that >80% of As exists as As(v) with <14% of As associated with sulfides in 5 Guizhou coal samples, confirming published but unexplained results. An As-Fe shell at 3.25-3.29 Å in the As EXAFS suggests that this As(v) is adsorbed on Fe(iii) oxyhydroxides as evidenced by Fe EXAFS in these coal samples. Significantly, lower Fe-Fe coordination numbers (CN) of 0.6-1.1 relative to those in 2-line ferrihydrite (CN = 1.6) and goethite (CN = 2.1) suggest that these Fe(iii) oxyhydroxides are likely Fe-OM nanoaggregates protected by OM encapsulation and adsorption of arsenate. Such structurally stabilized composites of As(v)-Fe(iii)-OM may be more widely distributed and allow oxidized As and Fe to persist in other organic-rich, reducing environments.