Evidence of methylmercury production and modification of the microbial community structure in estuary sediments contaminated with wastewater treatment plant effluents

► Importance of the anoxic sediment compartment in estuarine environments in the mercury biogeochemical cycle. ► MeHg production is enhanced after WWTP-effluents contamination of anoxic sediments. ► MeHg production is linked to the presence and activity of the SRMs. ► MeHg production can be related to enrichment in bioavailable Hg and organic matter.