title: Arsenic Environmental Threshold Surpass in Estuarine Sediments: Effects of Bioturbation.
abstract: We investigate the distributions of the metalloid arsenic (As) and metals iron (Fe) and manganese (Mn) in the sediments of two pristine areas of a biological reserve in the Patos Lagoon Estuary. This area is occupied by Spartina alterniflora and by Neohelice granulata crab colonies and low concentrations of As are expected. The bioturbation/bioirrigation of sediments by crabs and the roots of plants lead to the penetration of oxygen below the oxic/suboxix division and the subsequent precipitation of Fe-Mn hydroxides. Ferruginous incrustations and nodules along roots and crab channels propagate to depths of over 35 cm and sediment contains up to 33 mg kg- 1of As. The metalloid distribution in sediments is strongly correlated with that of Fe but not with Mn. This study revealed that areas with biologically disturbed sediments could demonstrate contamination in As, which is not anthropogenic in origin.
authors.affiliation: Oceanography Institute, Federal University of Rio Grande, Av. Itália km 08 Campus Carreiros, Rio Grande, RS, 96201-900, Brazil. larissap.costa@hotmail.com.
authors.forename: L
authors.initials: L
authors.lastname: Costa
authors.affiliation: Oceanography Institute, Federal University of Rio Grande, Av. Itália km 08 Campus Carreiros, Rio Grande, RS, 96201-900, Brazil.
authors.forename: N
authors.initials: N
authors.lastname: Mirlean
authors.affiliation: Oceanography Institute, Federal University of Rio Grande, Av. Itália km 08 Campus Carreiros, Rio Grande, RS, 96201-900, Brazil.
authors.forename: F
authors.initials: F
authors.lastname: Garcia
mesh_terms: D001151:Arsenic / Q000032:analysis*; D004784:Environmental Monitoring; D063366:Estuaries; D019015:Geologic Sediments / Q000737:chemistry*; D007501:Iron / Q000032:analysis*; D008345:Manganese / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D014874:Water Pollutants, Chemical; D008345:Manganese; D007501:Iron; D001151:Arsenic
keywords: Arsenic; Bioturbation; Contamination; Sediments