Arsenic in Brazilian tropical coastal zone

摘要

High concentration of arsenic (As) has been found in broad areas of the Brazilian tropical coastal zone. In this region, some carbonate tropical beaches have been enriched with As. High levels of As in sediments correlate with detritus material of calcareous algae involved in diagenetic processes. The As anomalies can be generated by the burial of marsh-lacustrine sediments containing As. Source of As is not clear, but oxyhydroxides layers of Tertiary sediments on the coastline (Barreiras Group) play an significant role. High concentrations of As were detected in groundwater in the Paraiba do Sul delta. The deltaic shallow groundwater aquifer is enriched with As fixed by authigenic sulfides. Arsenic speciation in the marine biota (A?u, Rio de Janeiro) shows that its organic fraction predominates in all samples, representing more than 95% of total As and the main compound is arsenobetaine.