Immobilization of arsenic in soil using modified bentonite and red mud to reduce its bio-availability in Brassica juncea

The influence of modified clay mineral and red mud on biological yield and arsenic bioavailability to mustard were investigated. The total biomass of the mustard was increased by application of clay mineral and red mud products. At higher doses (5.00 g/kg), Fe-bentonite treated soil recorded the highest total plant biomass (11.2 g/pot). DMSO-bentonite (1.23 mg/kg) and Fe-bentonite (1.28 mg/kg) were proved to be most effective in reducing the extractable arsenic concentration in soil at the rate of 5.00 g/kg doses. These products also help in lowering the hazard quotient (0.20–0.08) values for human consumption of arsenic through mustard leaf. This means that modified types of bentonites and red mud boost mustard productivity by reducing arsenic concentration

Assessing equilibria of organo-arsenic complexes and predicting uptake of arsenic by wheat grain from organic matter amended soils

In view of limited information, a laboratory experiment was conducted to study the stability of organo-arsenic complexes as affected by competing anions i.e. phosphate, nitrate and sulphate. For this purpose, humic acid (HA) and fulvic acid (FA) were extracted from farmyard manure (FYM), vermicompost (VC), sugarcane bagasse (SB) and soil. A pot experiment was also conducted with 4 levels each of arsenic (As) (10, 20, 30 and 40  mg  kg−1) and amendments (no amendment, FYM, VC and SB at the rate of 10  t  ha−1 each). Results indicate that stability of FA extracted from sugarcane bagasse have the highest stability constant (log K) as 9.77 and the corresponding mole ratio (x) value of 1.51. The phosphate was the most effective in replacing As from organo-As complexes followed by sulphate and nitrate. Under pot culture study, As content in wheat grain was the lowest in sugarcane bagasse amended soil followed by FYM and VC at all levels of As application. Solubility-free ion activity model was most effective in predicting As uptake by wheat grain based on Olsen extractable As, pH and Walkley & Black organic C. Efficacy of organic amendments in reducing health hazard for intake of As through consumption of wheat grain grown on contaminated soil was also reflected in the values of hazard quotient (HQ)

Risk Assessment of Arsenic in Wheat and Maize Grown in Organic Matter Amended Soils of Indo-Gangetic Plain of Bihar, India

Recent outbreak of geogenic arsenic (As) contamination in the Gangetic Delta basin of Bihar drew due attention of researchers as prolonged consumption of As-contaminated drinking water and food leads to arsenicosis, with the symptoms of pigmentation and keratosis in human. Although some information on As content in rice grain grown on contaminated soil is available specific to some areas of Bihar, practically no such information is available on wheat and maize crops. The present field experiment was conducted to evaluate the efficacy of organic amendments in reducing the availability of As in contaminated soils, followed by its uptake by wheat and maize. Accumulation of total As in wheat and maize grains varied from 0.02 to 0.11 mg kg−1 and from 0.23 to 0.29 mg kg−1, respectively, whereas available As in post-harvest soil varied from 1.07 to 1.33 mg kg−1 for wheat and from 1.10 to 1.24 mg kg−1 for maize. The organic amendments reduced the As accumulation in wheat grain to the extent of 84% (sugarcane bagasse (SB)), 50% (rice straw) and 40% (paddy husk (PH)) compared with control. Similarly, As content in maize grain was the lowest in SB-treated soil followed by rice straw and PH. Solubility-free ion activity model, based on pH, organic carbon and Olsen extractable As, was effective in predicting the As uptake by wheat and maize grains to the extent of 75% and 87%, respectively. Impact of organics in reducing health hazard for intake of As through consumption of wheat and maize grains grown on contaminated soil was also reflected in the values of the corresponding hazard quotient (HQ)

Assessing the Impact of Altered Clay Mineral and Red Mud Derivatives on the Characteristics of Mustard (B. juncea) and the Soil Arsenic Content

A pot experiment was conducted during the winter season (rabi) of 2020-21 at ICAR-Indian Agricultural Research Institute, New Delhi. Indian mustard (Brassica juncea) was cultivated to investigate the impact of modified clay mineral (Bentonite) and Red mud on yield characteristics and total arsenic content in the soil. The main objective was to examine how the application of modified clay mineral and red mud (Fe-exchanged bentonite, Dimethyl sulfoxide-intercalated bentonite, and Iron-exchanged red mud) would affect the yield attributes of Indian mustard. The initial soil's total arsenic content was 16.2 mg kg-1. The results revealed that all the mentioned treatments led to a significant increase in leaf biomass and root volume compared to the control pot. Significantly, highest leaf biomass (g pot-1) was recorded in Fe-exchanged bentonite (4.10 g pot-1) followed by Dimethyl sulfoxide-intercalated bentonite (4.00 g pot-1), and Iron-exchanged redmud (3.93 g pot-1) respectively at the rate of 5.00 g product per kg soil. The highest root volume (6.6 cm2) was observed in soil treated with 5.00 g kg-1 of Fe-exchanged bentonite. Dimethyl sulfoxide-intercalated bentonite, and Iron-exchanged red mud also showed positive effects but to a lesser extent. total As content in contaminated soil was thoroughly investigated, and the results revealed that these clays did not exert a significant influence on the total As content under the given application rates

Assessing Soil Degradation and Risk in Relation to Metal Pollution in Hindon River Water-Irrigated Soils of Western Uttar Pradesh of India

Soil degradation with metal pollution was assessed in polluted river water-irrigated soils. Human health risk from ingestion of metal by way of eating of edible portion of plants, raised on these soils, was predicted based on the free ion activity in contaminated soils followed by their movement to food-chain of human, using solubility-free ion activity model (FIAM). Soil quality index (SQI) was found to be lowest (PCA-SQI = 0.28) in river water-irrigated soils collected from Nithari and Barnawa village of Uttar Pradesh, India. Degree of soil health degradation due to metal accumulation as indicated by PCA-SQI follows the order: Nithari = Barnawa > Makreda > Rewari > Parsi > Kinauni. Plants grown on soils irrigated with river water showed higher accumulation of metals like zinc, copper, nickel, lead, and cadmium compared to plants raised on tube well-irrigated soils. Variation in metal content in plants grown in river as well tube well-irrigated soils could be successfully predicted by solubility-free ion activity model. Suitability of crops (rice grain, spinach, carrot, cucumber, pumpkin) as raised on river water-irrigated soils for human consumption was expressed in terms of hazard quotient, which were well within the safe limit

Arsenic in the Soil-Plant-Human Continuum in Regions of Asia: Exposure and Risk Assessment

In this review article, a comprehensive meta-analysis based on available literature information has been undertaken to make a relative comparison of total arsenic in rice grain. This involves analyzing the findings of various peer-reviewed studies that examined arsenic-contaminated Asian regions. Also, this article highlights the regional-level human health risks caused by the consumption of arsenic-contaminated rice in the three regions of Asia. Deriving such information at the continental level is of major importance in view of the need for proper monitoring and alleviating serious and continually emerging human health issues in arsenic-contaminated areas. One aim of this paper is to highlight the potential of a viable modeling approach for appraising the danger posed by arsenic in soil-plant-human system. There is an urgent need to fix the safe limit of bioavailable arsenic in soil because total arsenic in soil is not a good index of the arsenic hazard. Our hypothesis is finding out whether the modeling approach can be used in establishing a safe limit of bioavailable arsenic in soils with reference to human health. To achieve the above-mentioned objectives, we have selected reported rice grain arsenic content data from Asian countries following the PRISMA guidelines. Carcinogenic and non-carcinogenic risk was calculated following the US EPA’s guidelines. It emerged that adults in Asian countries are prone to a high risk of cancer due to their consumption of arsenic-contaminated rice. South Asia (SA), South East Asia (SEA), and East Asia (EA) exceeded the US EPA-prescribed safe limit for cancer risk with ~ 100 times higher probability of cancer due to rice consumption. The hazard quotient for the ingestion of arsenic containing rice was 4.526 ± 5.118 for SA, 2.599 ± 0.801 for SEA, and 2.954 ± 2.088 for EA. These figures are all above the permissible limit of HQ of 1. The solubility free ion activity model can predict arsenic transfer from soil to rice grain based on easily measurable soil properties and be used to fix the safe limit of bioavailable arsenic in paddy soils. The methods and findings of this review are expected to be useful for regional-level policymaking and mobilizing resources to alleviate public health issues caused by arsenic

Co-Application of Silicate and Low-Arsenic-Accumulating Rice Cultivars Efficiently Reduces Human Exposure to Arsenic—A Case Study from West Bengal, India

We investigated the effect of practically realizable doses of silicate on arsenic (As) uptake by differential-As-accumulating rice cultivars grown on geogenically As-polluted soil. The possible health risk from the dietary ingestion of As through rice was also assessed. In addition, a solution culture experiment was conducted to examine the role of root-secreted weak acids in differential As acquisition by rice cultivars. When grown without silicate, Badshabhog accumulated a much smaller amount of As in grain (0.11 mg kg−1) when compared to the other three varieties. Satabdi, IR-36, and Khitish accumulated As in grain beyond the permissible limit (0.2 mg kg−1) for human consumption. The application of silicate effectively reduced the As content in the grain, husk, and straw of all of the cultivars. The grain As content fell to 17.2 and 27.6% with the addition of sodium metasilicate at the rates of 250 and 500 mg kg−1, respectively. In the case of Khitish, the grain As content was brought down within permissible limits by the applied silicate (500 mg kg−1). The integrated use of low-As-accumulating cultivars and silicate has great potential to reduce the public health risks associated with As. A positive correlation between root-secreted total weak acid and grain As content could explain the different rice cultivars’ differential As acquisition capacity

Combining Fuzzy, Multicriteria and Mapping Techniques to Assess Soil Fertility for Agricultural Development: A Case Study of Firozabad District, Uttar Pradesh, India

Soil fertility (SF) assessment is an important strategy for identifying agriculturally productive lands, particularly in areas that are vulnerable to climate change. This research focuses on detecting SF zones in Firozabad district, Uttar Pradesh, India, for agricultural purposes, so that they can be prioritized for future management using the fuzzy technique in the Arc GIS model-builder. The model computing technique was also deployed to determine the different fertility zones, considering 17 soil parameters. The derived fuzzy technique outperformed the traditional method of dividing the sampling sites into clusters to correlate soil fertility classes with the studied soil samples. The prioritization of the soil factors and a spatial analysis of the fertility areas were carried out using the Analytic Hierarchy Process (AHP) and GIS tools, respectively. The AHP analysis outcome indicated that hydraulic properties had the highest weighted value, followed by physical and chemical properties, regarding their influence on SF. The spatial distribution map of physico-chemical properties also clearly depicts the standard classification. A fuzzy priority map was implemented based on all the classes parameters to identify the five fertility classes of the soil, namely very high (0.05%); high (16.59%); medium (60.94%); low (22.34%); and very low (0.07% of total area). This study will be of significant value to planners and policymakers in the future planning and development of activities and schemes that aim to solve similar problems across the country