Enhanced arsenic depletion by rice plant from flooded paddy soil with soluble organic fertilizer application

Arsenic dynamics in paddy soil under traditional manuring practices in Bangladesh

“…A similar finding on the role of OM on DOC and As porewater concentrations has been previously illustrated (Jia et al, 2013;Williams et al, 2011;Mestrot et al, 2011). DOC is generally negatively charged, it may compete with arsenate for the adsorption sites on the soil colloidal surface and facilitates arsenate desorption into the soil solution (Mohapatra et al, 2007, Yan et al, 2020. Again, DOC has positively charged amino groups on the surface that can combine with negatively charged As ions and thereby As is mobilized into soil solution (Yan et al, 2020, Williams et al, 2011.…”

“…OM mediated organic As in porewater in Bangladesh soils is also reported from Williams et al (2011) and Mestrot et al (2011). Moreover, organic manuring in paddy soils may produce arsines, the volatile As species (William et al, 2011, Yan et al, 2020.…”

“…The C:N ratio of an OM is a good indication of its quality; with high C:N ratio refer to low OM quality as well as a slow rate of biodegradation, while low C:N ratio represents improved quality as well as faster biodegradation (Chivenge et al, 2019). Yan et al (2020) stated that pig manure Dissolved Organic Matter (DOM) having more labile C mobilized more arsenic, whereas rice straw DOM containing more aromatic compounds mobilized less As. Porewater As concentration also increased with OM amendment, the highest As mobilization at 0 -5 cm depth observed in FYM amended plots (557 ± 25 µg/L) followed by rice straw amendment (502 ± 80 µg/L) then non-amended control plots (340 ± 45 µg/L) and at 5 -15 cm depth the highest As mobilization was observed in rice straw amended plots (585 ± 75 µg/L), followed by FYM amendment (440 ± 116 µg/L), then non-amended plots (421 ± 154 µg/L).…”

“…DOC is generally negatively charged, it may compete with arsenate for the adsorption sites on the soil colloidal surface and facilitates arsenate desorption into the soil solution (Mohapatra et al, 2007, Yan et al, 2020. Again, DOC has positively charged amino groups on the surface that can combine with negatively charged As ions and thereby As is mobilized into soil solution (Yan et al, 2020, Williams et al, 2011. Further, the arsenate mobilized into soil solution is reduced into arsenite through reductive dissolution where DOC plays the major role by donating electron (Islam et al, 2004, Arao et al, 2011, Qiao et al, 2019.…”

Distinct response of arsenic speciation and bioavailability to different exogenous organic matter in paddy soil

“…Commonly, the speciation transformation of As in soils is related to both abiotic and biotic factors. The impact of organic matter is particularly complex (He et al, 2020;Qiao et al, 2019). On one hand, organic matter could favor As mobilization through mediating the redox condition (Wang et al, 2017).…”