Formation of dimethyldithioarsinic acid in a simulated landfill leachate in relation to hydrosulfide concentration

Abstract

Dimethyldithioarsinic acid (DMDTA(V)), present in such intense sources as municipal landfill leachate, has drawn a great deal of attention due to its abundant occurrence and different aspect of toxicity. The hydrosulfide (HS(-)) concentration in leachate was studied as a major variable affecting the formation of DMDTA(V). To this end, the HPLC-ICPMS system equipped with the reversed-phase C18 column was used to determine DMDTA(V). Simulated landfill leachates (SLLs) were prepared to cover a mature landfill condition with the addition of sodium sulfate and sulfide at varying concentrations in the presence of dimethylarsinic acid (DMA(V)). The concentration of sodium sulfide added in the SLLs generally exhibited a strong positive correlation with the concentration of DMDTA(V). As such, the formation of DMDTA(V) in the SLLs is demonstrated to be controlled by the interactive relationship between DMA(V) and the HS(-).

Kinetics of Dimethylated Thioarsenicals and the Formation of Highly Toxic Dimethylmonothioarsinic Acid in Environment

“…Thus, microbial action can increase both the concentration of methylated As species by methylation from inorganic species and the sulfide concentration by sulfate reduction, 25 causing a rise in reaction rate. An et al 26 confirmed the chemical formation of DMDTA V in simulated landfill leachate and the relationship with sulfide. Landfill leachates under anaerobic conditions show high organic material concentrations containing carboxylic acids as major constituents.…”

“…An et al confirmed the chemical formation of DMDTA V in simulated landfill leachate and the relationship with sulfide. Landfill leachates under anaerobic conditions show high organic material concentrations containing carboxylic acids as major constituents .…”

“…The bacterial generation of hydrogen sulfide was found to play a critical role in the transformation of As species within the landfill body. When DMA V was spiked into simulated landfill leachates containing sulfide (pH 7.5), DMDTA V was formed after 30 days . In groundwater samples, the transformation of As species via the slow conversion of mono- or dimethylated thioarsenicals into their oxy-analogues (such as DMDTA V → DMMTA V → DMA V ) was observed during storage without preservation, with a half-life of ∼1 month at 4 °C .…”

“…When DMA V was spiked into simulated landfill leachates containing sulfide (pH 7.5), DMDTA V was formed after 30 days. 26 In groundwater samples, the transformation of As species via the slow conversion of mono-or dimethylated thioarsenicals into their oxy-analogues (such as DMDTA V → DMMTA V → DMA V ) was observed during storage without preservation, with a half-life of ∼1 month at 4 °C. 9 In addition, the loss of dithiospecies, which is accompanied by an increase in the corresponding monothio-species, was observed after acidification with hydrochloric acid.…”

Preparation of DMMTA^V and DMDTA^V Using DMA^V for Environmental Applications: Synthesis, Purification, and Confirmation

“…Species included in the stock solutions of DMMTA V and DMDTA V should be examined prior to every analysis, although this protocol suggests storage conditions of 4 ˚C in the dark, which maintains synthesized DMMTA V and DMDTA V with, respectively, 2.2% and 5.8% transformation during the 13 weeks of analysis (Figure 2). , and minor fragments m/z measured by ESI-MS was reproduced from literature 5,13,14,17,19,20,21,22,23,24 . Note that m/z peaks may vary with instrumental conditions and/or matrices of the stock solutions.…”