Search

Arsenic (As) and cadmium (Cd) are unnecessary metal(loids) toxic at high concentration to plants and humans, hence lessening their rice grain accumulation is crucial for food security and human healthiness. Charred eggshell (EB), corncob biochar (CB), and eggshell-corncob biochar (ECB) were produced and amended to As and Cd co-polluted paddy soil at 1% and 2% application rates to alleviate the metal(loids) contents in rice grains using pot experiments. All the amendments increased paddy yields at 1%, while EB at 2% significantly reduced the yields compared to untreated control. The resulting yield loss in 2%EB was from the combined effects of its high CaCO 3 supplementation, and the increment of rhizosphere soil pH which could insolubilize plant nutrients. The amendments were inefficient in decreasing rice grain As (As Grain ), but all the treatments significantly reduced the rice grain Cd (Cd Grain ) at both 1% (44.4-77.1%) and 2% (79.8-91.5%) application rates compared to that of control. Regression analysis for contribution weights of control factors revealed that rhizosphere soil Eh and pH were vital influential factors regulating the As Grain , whereas porewater Cd was main factor controlling Cd Grain accumulation. These investigations indicated that the Ca-enriched eggshell-corncob biochar even at high application rate (i.e., 2%ECB) could be a potential tactic for grain accumulation remediation of the cationic pollutant (i.e., Cd) from the paddy soil to rice grain scheme with concurrent increase in rice yields., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Arsenic (As) and cadmium (Cd) are nonessential toxic metal(loids) that are carcinogenic to humans. Hence, reducing the bioavailability of these metal(loids) in soils and decreasing their accumulation in rice grains is essential for agroecology, food safety, and human health. Iron (Fe)-enriched corncob biochar (FCB), Fe-enriched charred eggshell (FEB), and Fe-enriched corncob-eggshell biochar (FCEB) were prepared for soil amelioration. The amendment materials were applied at 1% and 2% application rates to observe their alleviation effects on As and Cd loads in rice paddy tissues and yield improvements using pot trials. The FCEB treatment increased paddy yields compared to those of FCB (9-12%) and FEB (3-36%); this could be because it contains more plant essential nutrients than FCB and a lower calcite content than that of FEB. In addition, FCEB significantly reduced brown rice As (As BR , 29-60%) and Cd (Cd BR , 57-81%) contents compared to those of the untreated control (CON). At a 2% application rate, FCEB reduced the average mobility of As (56%) and Cd (62%) in rhizosphere porewater and enhanced root Fe-plaque formation (76%) compared to those of CON. Moreover, the enhanced Fe-plaque sequestered a substantial amount of As (171.4%) and Cd (90.8%) in the 2% FCEB amendment compared to that of CON. Pearson correlation coefficients and regression analysis indicated that two key mechanisms likely control As BR and Cd BR accumulations. First, rhizosphere soil pH and Eh controlled As and Cd availabilities in porewaters and their speciation in the soil. Second, greater Fe-plaque formation in paddy roots grown in the amended soils provided a barrier for plant uptake of the metal(loids). These observations demonstrate that soil amendment with Fe-enriched corncob-eggshell biochar (e.g., 2% FCEB) is a prospective approach for the remediation of metal accumulation from the soil to grain system while simultaneously increasing paddy yield., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The aim of this study was to produce magnetic biochar for the removal of As (III) from the aquatic environment. Magnetic biochar (MBC) was prepared from corn straw‑derived biochar. Pristine biochar (BC) was impregnated with iron oxide and relative analyses were performed on the adsorption capacity of BC's and MBC's. After impregnation, the specific surface area of MBC800-0.6 300 increased from 79.66 to 309.7 m 2  g -1 and superparamagnetic magnetization was about 9.75 emu g -1 contributed by the contained Fe 3 O 4 . Results of MBC800-0.6 300 showed maximum adsorption capacity (Q max ) 22.94 mg g -1 for As (III) based on Langmuir model which is 5.71 times higher than the adsorption capacity of BC800 (4.02 mg g -1 ). The adsorption of As (III) increased significantly due to the successful loading of iron oxide and the increased oxygen functional groups that were confirmed by XPS and FTIR results. The removal of As (III) followed Langmuir isotherm model and pseudo-second-order (R 2  ≥ 0.99), indicated that the adsorption rate was monolayer and depended on the chemical adsorption process, respectively. Consequently, the simple preparation procedure and high adsorption performance suggest that MBC800-0.6 300 could be used as an environment-friendly and extremely effective adsorbent for As (III) removal from aqueous environment.

The mining and smelting of lead-zinc (Pb-Zn) ores cause widespread As contamination. The fractions and colloidal distribution of As associated with Fe oxide minerals in Pb-Zn mine-contaminated soils have not been well understood. In this study, As fractions associated with Fe oxide minerals in Pb-Zn tailings- and smelter-contaminated soils were compared using sequential extraction techniques. Kinetic experiments were conducted to characterize the reactivity of Fe oxide minerals. The distribution of As and Fe oxide minerals in soil colloids were analyzed. The results show that in mining-contaminated soils (both tailings and smelter) the relatively active fraction (amorphous hydrous oxide-bound As, As F3 ) has a strong relationship with easily reducible Fe (Fe ox1 ). In smelter-contaminated soils, relatively stable fractions (crystalline hydrous oxide-bound As, As F4 ) were closely associated with reducible Fe (Fe ox2 ). Although the average proportions of specifically-bound As (As F2 ) and As F3 in contaminated soils were similar, high As release in tailings-contaminated soils was observed because of the high reactivity of Fe oxide minerals in those soils compared with that in smelter-contaminated soils. Some slightly polluted soils with high pH and TOC concentrations formed As-bearing colloidal suspensions. Especially in smelter-contaminated soils, many small-sized soil colloids could facilitate As migration with surface runoff or vertical transport., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Arsenic and cadmium (As/Cd) are toxic elements which negatively impact the health and productivity of rice plants by subjecting them to stress. To address these issues, we developed three biochar amendment materials derived from plant-based corn-stover with iron-magnesium modification (FM@CB), char sourced from animal-based eggshells with iron-magnesium modification (FM@EB), and a blend (1:1, w/w) of both (FM@CEB). Batch adsorption experiment revealed that FM@CB exhibited a Langmuir sorption capacity of 77 mg g−1 for As(III) and 107 mg g−1 for Cd(II). In contrast, FM@EB showed values of 63 mg g−1 for As(III) and 115 mg g−1 for Cd(II), both observed in mixed systems. The exothermic dual adsorption mechanisms could include ion exchange, cation-anion bridging, complexation with surface functional groups, and precipitation processes. Pot trials were conducted, and the findings unveiled a substantial enhancement in rice grain yield with a 2% application of FM@CB, FM@EB, and FM@CEB. Specifically, there was a notable increase of 21.9%, 34.9%, and 37.6%, respectively. Simultaneously, the application led to a reduction in grain As levels by 34.4%, 53.2%, and 42.6%, and grain Cd levels by 48.7%, 71.2%, and 59.9%, respectively, in comparison to the no-amendment control condition. Our study observed a transformation in the soil's microbial community, as beneficial bacterial genera such as Anaeromyxobacter , Citrifermentans , and Desulfovibrio emerged to assist in the detoxification of these metal contaminants. Concurrently, the application of these materials led to a reduction in harmful bacterial genera like Pseudomonas , Flavobacterium , and Massilia. In addition, these amendments decreased the bioavailable As/Cd fractions in the soil and promoted the root-iron-plaque, which effectively sequesters these contaminants, rendering rice quality improvement. Ultimately, the use of these amendments, particularly FM@CEB, holds the promise of protecting rice from harmful metal(loid)s contaminants, increasing yields, and revitalizing the soil. The presence of these unique bacterial genera, especially those capable of detoxifying As/Cd, plays a crucial role in ensuring a healthier and more secure environment for all living organisms. [Display omitted] • Fe–Mg modified plant/animal-based FM@CB, FM@EB, and FM@CEB were prepared. • Biochars' sorption capacity: 63−77 mg g−1 for As(III), 107−115 mg g−1 for Cd(II). • Sorption mechanisms: ion exchange, cation-anion bridge, complexation, precipitation. • Beneficial bacteria aid As/Cd detoxification in treated soil. • 2% amendments significantly reduce bioavailable As/Cd in soil and rice grain. [ABSTRACT FROM AUTHOR]

The perilousness of arsenic and cadmium (As–Cd) toxicity in water and soil presents a substantial hazard to the ecosystem and human well-being. Additionally, this metal (loids) (MLs) can have a deleterious effect on rice quality and yield, owing to the existence of toxic stress. In response to the pressing concern of reducing the MLs accumulation in rice grain, this study has prepared magnesium-manganese-modified corn-stover biochar (MMCB), magnesium-manganese-modified eggshell char (MMEB), and a combination of both (MMCEB). To test the effectiveness of these amendments, several pot trials were conducted, utilizing 1% and 2% application rates. The research discovered that the MMEB followed by MMCEB treatment at a 2% rate yielded the most significant paddy and rice quality, compared to the untreated control (CON) and MMCB. MMEB and MMCEB also extensively decreased the MLs content in the grain than CON, thereby demonstrating the potential to enrich food security and human healthiness. In addition, MMEB and MMCEB augmented the microbial community configuration in the paddy soil, including As–Cd detoxifying bacteria, and decreased bioavailable form of the MLs in the soil compared to the CON. The amendments also augmented Fe/Mn-plaque which captured a considerable quantity of As–Cd in comparison to the CON. In conclusion, the utilization of multifunctional biochar, such as MMEB and MMCEB, is an encouraging approach to diminish MLs aggregation in rice grain and increase rice yield for the reparation of paddy soils via transforming microbiota especially enhancing As–Cd detoxifying taxa, thereby improving agroecology, food security, and human and animal health. [Display omitted] • MMEB and MMCEB at 2% rate significantly increased rice yields compared to control and MMCB. • MMEB followed by MMCEB was most effective in reducing grain accumulation of As and Cd. • All the amended treatments significantly reduced bioavailable form of As and Cd. • All the amendments pointedly reduced As and Cd tolerant Pseudomonas bacterial genus. • MMEB application increased heavy metal-detoxifying bacterial genera than MMCB and MMCEB. [ABSTRACT FROM AUTHOR]

Intake of heavy metals from contaminated agricultural products represents a significant pathway for human exposure. Banglish village in the Comilla district is one of the most devastated arsenic contaminated areas in Bangladesh. This study focus whether is solely responsible for causing arsenicosis or whether some other heavy metals have a synergistic effect on the toxicity of . The study sampled various leafy and non-leafy vegetables and groundwaters were analyzed by using the Proton Induced X-ray Emission (PIXE) method. The results revealed that both the vegetables and the groundwater were highly contaminated with and lead , although the contents in the vegetables and the groundwater varied depending on species and tube wells. and concentrations in the edible part of all tested vegetables and in groundwater exceeded the permissible intake levels of the Food and Agriculture Organization (FAO) and the World Health Organization (WHO). The findings inferred that the inhabitants of the study area are experiencing health risks resulting from the intake of and , and that might have a synergistic role with by aggravating the arsenicosis. The potential health risks due to is being reported for the first time in Bangladesh. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the relationships between arsenic () levels in human hair and demographic factors on accumulation in humans. Hair samples of 619 subjects (383 females and 236 males), including 390 confirmed arsenicosis patients, 11 fish and six vegetable samples were analyzed using the Proton Induced X-ray Emission (PIXE) method. The results revealed that in hair accumulates in different patterns for males and females in accordance with age. Within patient groups, male patients accumulated higher amounts of than female patients. For all individuals, middle aged females accumulated higher amounts in hair than children, adolescents and females over 50 years old, while children, adolescents and males over 50 accumulated higher amounts of than middle aged males in both villages. Surprisingly, high levels of concentrations were found in hair samples of those living near safe drinking water in both villages, irrespective of age and sex. There were weak positive correlations between hair levels and groundwater levels in both villages. Furthermore, toxic levels of were found in different kinds of food products. Taken together, these findings demonstrate that accumulation in hair is dependent not only on water contamination, but also on food contamination. [ABSTRACT FROM AUTHOR]

This study was carried out to investigate biological and statistical nature of arsenicosis risks on a severely arsenic (As) affected population in the Banglish village in Comilla district of Bangladesh. Subject's hair As and vegetables As levels were estimated by PIXE method, and arsenicosis status of the subject was examined by a physician. Arsenicosis was found in 45% female and 61% male subjects. Arsenic levels > 0.50 ppm showed greater arsenicosis risks that significantly varied with subject's sex and age. Unlike children, young (≥10 years) to middle aged (~49 years) population were significantly affected by arsenicosis. Logistic regression model analysis showed that arsenicosis risks are not only the devastating toxicity of As accumulation in human body through ingestion of contaminated drinking water, but the summation of all sources of As accumulation. Human hair As levels were found as the biomarker ranging from 0.03-8.3 μg/g in stage I arsenicosis patients, and from 1.1-56.9 ppm in the stage II patients up to 49 age. Hair As level was declined to 2.2-25.5 ppm at > 49 aged population. The findings inferred that groundwater As affecting the public health through contaminating total environment, that in turn posing an alarming situation in the study area. [ABSTRACT FROM AUTHOR]

Arsenic concentration in 13 well waters, 9 pond waters, 10 agricultural waters and a coconut juice taken in Comilla district, Bangladesh, where the problem of arsenic pollution is the most severe, was investigated. High-level arsenic is detected even in the well water which has been kept drinking by the people. Relatively high arsenic concentration was detected for some pond and farm waters even though the sampling was performed just after the rainy season and the waters were expected to be highly diluted. Clear relationship was observed in elemental compositions between the pond water and the coconut juice collected at the edge of the water. These results are expected to become the basic information for evaluating the risk of individual food such as cultured fishes, shrimps and farm products, and for controlling total intakes of arsenic. In order to solve the problem of transportation of water samples internationally, a simple method of target preparation performed at the sampling cite was established and its validity was confirmed. All targets were prepared at the sampling cites in this study on the basis of this method. [ABSTRACT FROM AUTHOR]