HEAVY METAL DISTRIBUTION IN SOIL PROFILES OF A DUMPING AREA: A CASE STUDY IN THE CAMPOS DOS GOYTACAZES MUNICIPALITY,RIO DE JANEIRO, BRASIL.

Carlos Eduardo Rezende(1); Carlos Eduardo Veiga de Carvalho(1); Sérgio Tibana(2); Luiz Augusto Crespo Monteiro(2) & José Tavares Araruna Júnior(2)

Universidade Estadual do Norte Flumenense, Av. Alberto Lamego 2000,

Campos dos Goytacazes, 28.015-620, Rio de Janeiro, Brasil

(1)Laboratório de Ciências Ambientais; (2)Laboratório de Engenharia Civil

(Email:crezende@cbb.uenf.br; Tel: +55 24 7263709; Fax: +55 24 7263720)

The existence of municipal waste in urban areas provide several changes to human and ecosystem health, as well as to the landscape aesthetic value. In January 1999 a first prospective visit was made and 16 soil samples in different depths were collected. All samples were analyzed for grain size distribution, organic matter contents and metal concentrations. Grain size was quantified sieving dried soils and silt + clay content was based on Stolke law. Organic matter (OM) was determined using 4 g of dried soil by loss ignition in muffle furnace at 450o C/24h. Two grams of dried soil samples (bulk fraction) were leaching by 20 mL of HCl 0,5 N during 24 h. All extracts analyzed by ICP-AES (Liberty Series II - Varian). Grain size distribution divided the soils samples in 2 groups based on silt + clay content: a) > 50% (N= 6) and b) < 50% (N= 10). The first group presented average of 63% (range = 50 to 93%); and the second presented an average of 38% (range = 23 to 48%). Organic matter distribution along the profile showed the following values: a) 0 - 5.5 m from 8 to 15%; b) 5.5 ^Ö 6.5 m from 11 to 30%; and c) 6.5 - 7.5 m from 4 to 12%. Data on element content are presented here: a) Cadmium, Ni and Sn was not detectable for all samples (<0.10 µg/g, <0.20 µg/g and <40 µg/kg, respectively) and b) the other heavy metals in weak acid solution varied: Al= 108 to 886 µg/g; Fe= 28 to 349 µg/g; Cr= <0.20 to 2.54; Cu= 0.43 to 8.74 µg/g; Mn= <0.10 to 3.00; Pb= 0.34 to 3.37 µg/g; V= <0.20 to 19.8; and Zn= 0.25 to 9.86. In all cases, the high content of OM appear to be controlling the element concentration along the profile.

Key words: dumping, organic matter and grain size.