Effect of organic amendments on arsenic solubilization in soils during long-term flooded incubation

Abstract

Rice consumption is considered an important arsenic source for the population in Asian countries. Previous studies showed increase in arsenic solubility in flooded soils and arsenic uptake by rice plants with the application of organic amendments, while contrasting results were also reported. Here, we comprehensively examined the effect of three types of organic amendments on arsenic solubility during long-term flooded soil incubation. The amendments examined were categorized as (1) plant-based composts, (2) cattle manures, and (3) fermented livestock (swine and poultry) droppings. The dissolved arsenic in all soils with fermented livestock dropping was significantly greater than that in control soils at 10 and 39 days after incubation. The soils with two cattle manures also contained significantly greater amounts of dissolved arsenic than control soils at day 39, while the rest of the amendments did not increase arsenic solubility. At day 80, the amount of dissolved arsenic in all soils became comparable. Tukey's test demonstrated that the relative ratio of dissolved arsenic in soils with fermented livestock droppings to control soils was significantly greater than those with the plant-based composts and cattle manures at days 10 and 39. Furthermore, the solubilizing effect of some organic amendments was mostly explained by promotion of decrease in soil Eh, rather than increase in dissolved organic carbon. Thus, it could be concluded that fermented livestock droppings potentially have a greater risk of solubilizing As than plant-based composts and cattle manures, because of their greater ability for accelerating soil reduction, associated with their higher bio-decomposability.

Arsenic Uptake and Accumulation Mechanisms in Rice Species

“…OM may also affect plant growth and As accumulation in rice plants. OM, theoretically, insolubilises As over certain mechanisms, such as the binding of As with phenolic OH, carboxylate and sulfhydryl groups with/without ternary complexes [82]. Norton et al [83] stated that OM is important in the mobilisation of As from paddy fields because microbes utilising OM consume oxygen that results in a reduction in redox potential, which leads to As dissolution from FeOOH.…”

Microplastic pollution in aquatic environments may facilitate misfeeding by fish

“…For behavioural analysis (trials 1 and 2), we used a generalized linear model (GLM) with a binomial error distribution and logit link function with a binomial response variable of “captured” or “not captured” and exposure period, body size, and interactions as explanatory variables. The relationship between capture time and exposure period was analyzed with the non-parametric Spearman’s rank correlation test, because of their potential nonlinear relationship, including zero value (Suda and Makino, 2016). All statistical analyses were performed using JMP Pro.15, and a probability of p < 0.05 was considered significant.…”

“…The relationship between capture time and exposure period was analyzed with the non-parametric Spearman's rank correlation test, because of their potential nonlinear relationship, including zero value (Suda and Makino, 2016). All statistical analyses were performed using JMP Pro.15, and a probability of p < 0.05 was considered significant.…”

Inorganically modified clay minerals: Preparation, characterization, and arsenic adsorption in contaminated water and soil

“…Ghosh et al (2012) used farm yard manure and compost to make chelation of arsenic with humate compounds and immobilize it in soils. While the influence of organic matter on the mobility and bioavailability of arsenic species are ambiguous (Suda and Makino, 2016;Wang et al, 2016), some inorganic amendments such as iron compounds, phosphates, alkaline compounds, gypsum, biosolid, red mud, fly ash and clay minerals were found effective in immobilizing As in soils (Lombi et al, 2004;Kumpiene et al, 2008;Miretzky and Cirelli, 2010;Lee et al, 2011;Lim et al, 2016). However, many of these materials are expensive and still do not have standard protocol of practical soil application.…”