Chromium in water, suspended particles, sediments and biota in the Irajá River estuary

Abstract

Analyses of chromium concentrations in waters, suspended particles, bottom sediments, fish ( Poecilia reticulata), plan ts (Paspalum vaginatum, Sesuvium portu- lacastrum, Philoxeros vermicularis), soils and barnacles (Balanus sp.) were per- formed from August 1976 to September 1980 in samples collectedfrom the lraj6 River and inside its estuary in Guanabara Bay (Rio de Janeiro, Brazil). Sediments and water from the Iraj6 River showed chromium concentrations of 17 536 and 23.39ppm--a thousand times higher than the published data for freshwater systems. Chromium removed from solution by bottom sediments reaches Guanabara Bay linked to particulate matter. Fish and emergent grass inside the river concentrate chromium from water and/or sediment, returning the metal to the system as detritus. Soil and plants inside the estuary concentrate chromium thirty and ten times higher than in the control area. The vegetal community exhibits a concentration factor smaller than that related to soil and prevents the return of chromium to the estuarine waters. Inside the Guanabara Bay, Balanus sp. appears to be an effective biological monitor as it concentrates chromium in soft tissues 103 times higher than valuesfound in suspended particles (0"012 #g ml - 1)