Arsenic contamination caused by roxarsone transformation with spatiotemporal variation of microbial community structure in a column experiment

Arsenic contamination from roxarsone in livestock manure is common,and livestock manure continuously accumulates in the open environment.Evaluations of the environmental processes of As mobilization and transformation are critical for predicting the fate of As compounds after roxarsone degradation.In this study,spatiotemporal variations in As species and microbial community structure were characterized using laboratory column experiments with background soil collected from Yanggu County(northern Shandong Plain,China),a region of intense poultry production.Organic and inorganic arsenic were detected by high-performance liquid chromatography(HPLC)and HPLC with hydride generation atomic fluorescence spectrometry(HPLC-HG-AFS),respectively.High-throughput sequencing technology was used to describe microbial diversity.Results showed that roxarsone was transformed completely within 7 days,and A_(s)(Ⅲ)and As(Ⅴ)were the major degradation products.The concentration of A_(s)(Ⅲ)was much lower than that of As(Ⅴ).The A_(s)(Ⅲ)concentration increased significantly after Day 14,whereas the A_(s)(Ⅴ)concentration increased significantly after Day 84,indicating that A_(s)(Ⅲ)was initially produced.The microbial community structure changed significantly as roxarsone transformed into various As compounds.A critical and dominant bacterial strain,norank_f__Family_XVⅢ,was found to be related to the degradation of roxarsone into As(Ⅲ).This study improves our understanding of the fate of As species released from poultry litter to soil and groundwater,which is a threat to human health and environment.