Potentially toxic metals of vegetable gardens of urban schools in Lages, Santa Catarina, Brazil/Metais potencialmente toxicos em hortas escolares na regiao urbana de Lages, Santa Catarina, Brasil

Urban environments are contaminated in many ways with persistent organic and inorganic pollutants as a result of anthropogenic activities, endangering human health and natural resources. The objective of the present study was to evaluate the soil contamination by cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) in 10 vegetable gardens of urban schools located near or on Botucatu sandstone outcrops of Guarani Aquifer in the urban areas of Lages, Santa Catarina, Brazil. In each garden, three soil samples at each position (in the soil immediately outside and the soil in the garden) were collected at a depth of 0-20 cm. The ISO 11466 method was used to extract the metals. Inductively coupled plasma optical emission spectrometry was used to quantify the elements and certified materials to evaluate the quantities (SRM 2709a--San Joaquin Soil--NIST). To evaluate the data, principal component analyses and cluster analyses were performed. The cluster analysis for the evaluated metals showed that the highest contents of elements were reported in three gardens. Values above the prevention value defined by resolution no. 420/2005 of the National Council for the Environment--Conselho Nacional do Meio Ambiente (CONAMA)--were reported for cobalt in one garden and copper in three gardens; thus, these areas were categorized as Class III areas. Principal component analysis explained 74.7% of the data and showed the enrichment of some elements within gardens. Key words: environmentally sensitive areas, urban gardens, environmental contamination. Ambientes urbanos sao contaminados de muitas maneiras com poluentes organicos e inorganicos persistentes como resultado de atividades antropicas, colocando em risco a saude humana e os recursos naturais. O objetivo do presente estudo foi avaliar a contaminacao do solo por cobalto (Co), cromo (Cr), cobre (Cu), manganes (Mn), niquel (Ni), chumbo (Pb) e zinco (Zn) em 10 hortas de escolas urbanas situadas proximo ou sobre areas de afloramento de arenito Botucatu do Aquifero Guarani, no municipio de Lages, Santa Catarina. Em cada horta, tres amostras de solo foram coletadas (dentro efora da horta) na profundidade de 0-20 cm. O metodo ISO 11466foi usado para extrair os metais. Utilizou-se espectrometria de emissao optica com plasma indutivamente acoplado (ICP OES) para quantificar os elementos e materiais certificados (SRM 2709a--San Joaquin Soil--NIST). Para avaliar os dados foi feita a analis