Estimating Arsenic Mobility and Phytotoxicity Using Two Different Phosphorous Fertilizer Release Rates in Soil

Arsenic contamination, impact and mitigation strategies in rice agro-environment: An inclusive insight

Arsenic (As) contamination and its adverse consequences on rice agroecosystem are well known. Rice has the credit to feed more than 50% of the world population but concurrently, rice accumulates a substantial amount of As, thereby compromising food security. The gravity of the situation lays in the fact that the population in theAs uncontaminated areas may be accidentally exposed to toxic levels of As from rice consumption. In this review, we are trying to summarize the documents on the impact of As contamination and phytotoxicity in past two decades. The unique feature of this attempt is wide spectrum coverages of topics, and that makes it truly an interdisciplinary review. Aprat from the behaviour of As in rice field soil, we have documented the cellular and molecular response of rice plant upon exposure to As. The potential of various mitigation strategies with particular emphasis on using biochar, seed priming technology, irrigation management, transgenic variety development and other agronomic methods have been critically explored. The review attempts to give a comprehensive and multidiciplinary insight into the behaviour of As in Paddy -Water - Soil - Plate prospective from molecular to post-harvest phase. From the comprehensive literature review, we may conclude that considerable emphasis on rice grain, nutritional and anti-nutritional components, and grain quality traits under arsenic stress condition is yet to be given. Besides these, some emerging mitigation options like seed priming technology, adoption of nanotechnological strategies, applications of biochar should be fortified in large scale without interfering with the proper use of biodiversity.

Effect of bioavailable arsenic fractions on the collembolan community in an old abandoned mine waste

Mine waste from abandoned mines poses a risk to soil ecosystems due to the dispersion of arsenic (As) in the mine waste to the nearby soil environment. Because the bioavailability of As varies depending on the As chemical fraction and exposure conditions, chemical assessment of As fractions in soil around mine waste is essential to understand their impact on soil ecosystem. Here, six sites around the mine waste were selected for investigating toxic effects of As-contaminant soil on Collembola community. To measure the As chemical fraction in soil and bioavailability, Wenzel sequential extraction employed. Meanwhile, the collembolans that live in each sampling site were identified at the species level, and the characteristics and composition of the collembola community were investigated. The mobility fraction (F1 + F2 + F3; MF) was related to the risk to the collembolan community, and the adverse impact of high MF appeared to lead to a decrease in abundance, richness, and Shannon index. According to non-metric multidimensional scaling analysis, F1, F2, F3, and pH were shown as the significant factor explaining the NMDS space. Especially, the sampling site with the highest concentration of F3 showed statistically different species composition from the other sites. In the case of As-contaminated soil around the old mine waste, the toxic effects of the remaining F3 in soil, as well as that of F1 and F2, should be fully considered. This study suggested that collembolan community could be used for understanding the impact of bioavailable As fraction in the old abandoned mine area.

Evaluation of factors affecting arsenic uptake by Brassica juncea in alkali soil after biochar application using partial least squares path modeling (PLS-PM)

Biochar application to As-contaminated soil can alter various soil chemical properties, and it can affect available As, plant As uptake, and As phytotoxicity. Increased dissolved organic carbon (DOC) and P released from biochar affect As behavior in the soil system. In this study, we evaluated the effect of biochar application on the chemical properties of soil and phytotoxicity in Brassica juncea using correlation analysis and partial least squares path modeling (PLS-PM). Biochar application increased electrical conductivity (EC), DOC, available P and available As. However, the increased available As did not significantly affect As uptake by B. juncea due to the decrease in the relative ratio and effect of available As with increase in available P derived from biochar. Moreover, biochar application negatively affected soil chemical properties (pH, EC, DOC, available P, and available As) and As uptake by B. juncea. Therefore, correlation analysis and PLS-PM analysis are useful tools to interpret the interactions among influencing factors in the soil-plant system. An approach at the equivalent molecular level rather than concentration should be adopted in future studies.

Assessment of Fraction and Mobility of Arsenic in Soil Near the Mine Waste Dam

Arsenic (As) contamination in abandoned mining areas has been of concern in Korea; hence, the reclamation and restoration of these areas must be conducted. Since large contaminated areas have not been restored yet, post management of restoration sites would be insufficient. The aim of this study was to monitor the pollution of environments near the waste dam in mining areas and to assess the fraction and mobility of As. Chemical assessment was conducted using sequential extraction and single extraction methods [Mehlich-3, 1N HCl, the simple bioavailability extraction test (SBET), and the synthetic precipitation leaching procedure (SPLP)], whereas biological assessment was conducted with a bok choy (Brassica campestris L. ssp. chinensis Jusl.) cultivation experiment. The results showed that the waste rock soil, forest soil, and sediments near the dam were contaminated with As. As a result of sequential extraction, most of the As in the soil of the upper part of the dam were observed to be tightly adsorbed (well-crystallized hydrous metal oxides and residual phases), whereas As in the forest soil of the lower part of the dam were observed to be relatively weakly bound (amorphous and poorly-crystallized hydrous metal oxides). These results show that As could be re-dissolved from secondary contaminated forest soil and spread to nearby environments. For the sustainable management of soil environment, an assessment of the fraction and mobility of As coupled with continuous monitoring are required.