Interaction of Arsenic with Zinc and Organics in a Rice (Oryza sativaL.)–Cultivated Field in India

Abstract

A laboratory experiment on an Inceptisol with pH 7.6, organic carbon 6.8 g kg-1, and 0.5 M NaHCO3 extractable arsenic 0.4 mg kg-1 was conducted to study the interaction effect of graded levels of arsenic (0, 5, and 10 mg kg-1) with zinc (0, 10, and 20 mg kg-1) and organics (0, 1, and 2% on soil weight basis) separately on the mobilization of arsenic in soils.The results show that the amount of 0.5 M NaHCO3 extractable arsenic at pH 8.5 increased with the progress of submergence up to 35 days. However, the increase in arsenic concentration was correlated with decreasing application of graded levels of Zn as zinc sulfate. The intensity of reduction varied with varying levels of Zn, being higher (0.73—2.72 mg kg-1) in the treatment where Zn was at 10 mg kg-1 and lower (0.70—1.08 mg kg-1) with Zn at 20 mg kg-1 application.The amount of arsenic content in the soil significantly decreased with the application of varying levels of organics. However, such depressive effect was found more pronounced with well-decomposed farm yard manure than that of vermicompost. The results of field experiments showed that the grain yield between continuous flooding (4.84 t ha-1) and intermittent flooding up to 40 days after transplanting then continuous flooding (4.83 t ha-1) with the application of ZnSO4 at 25 kg ha-1 did not vary. The lowest grain yield (3.65 t ha-1) was recorded in the treatment where intermittent flooding was maintained throughout the growth period without the application of Zn. The amount of arsenic content was, however, recorded much lower in the treatment where intermittent flooding throughout the growth period was maintained with ZnSO4.

Mobilisation of arsenic in soils and in rice (Oryza sativa L.) plants affected by organic matter and zinc application in irrigation water contaminated with arsenic

“…The phytotoxicity of arsenic is expected to be greater in sandy soils than in other types of soil, since sandy soil usually contain low amount of Fe and Al oxides and clays. Irrigation water, soils and plants from adjacent rice and wheat fields were analysed for arsenic and other elements and showed that rice and wheat grains were not contaminated by arsenic, but concentrations in rice roots exceeded 160 mg/kg due to an Fe-rich plaque around rice roots (Das et al 2005, Norra et al 2005). …”

“…The highest accumulation of arsenic was recorded in roots compared to stems, leaves and grains; it might be caused by As mobility within the plant, which would support the results reported by Liu et al (1985) who showed the distribution of arsenic in plants in the descending order (root > stem > leaf > edible part). Das et al (2005) reported that the accumulation of arsenic in rice root, stem, leaves and grains might be significantly decreased with the application of Zn, by management of irrigation water, or both. The values recorded in individual plant parts with the application of Zn under intermittent ponding throughout the growth period of rice compared to other water management practices were as follows: roots (7.15 mg/kg), stem (5.14 mg/kg), leaf (5.49 mg/kg) and grain (0.81 mg/kg).…”

Remediation of Arsenic Toxicity in the Soil-Plant System by Using Zinc Fertilizers

“…Correspondingly, it was reported that the toxicity of arsenic may be reduced by applying sulfates of zinc, iron and aluminum to the soil [28]. An increase in arsenic concentration was correlated with decreasing application of graded levels of Zn as Zn-sulfate was also reported [29].…”

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

“…The addition of OAs potentially increases (Xie and Huang 1998;Suda et al 2015) and decreases (Das et al 2005) dissolved As through a variety of mechanisms (see ''Introduction'' section). The present study showed different effects of three types of OAs on As solubility.…”

“…Organic matter potentially insolubilizes As through several mechanisms, such as binding of As with phenolic OH, carboxylate, and sulfhydryl groups with/ without ternary complex (cation bridging) (Thanagalasingam and Pickering 1986;Buschmann et al 2006;Langner et al 2011). Das et al (2005) reported the decrease in sodium hydrogen carbonate-extractable As during submerged soil incubation with a well-decomposed farm yard manure and vermicompost. Rahaman et al (2011) found that the application of OAs, and their combination, significantly decreased the As load of rice plants.…”