Contaminação do solo por metais pesados
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2013
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Sendo o solo, um recurso natural com uma multiplicidade de funções, torna-se urgente e necessário protegê-lo de todas as fontes de contaminação. O presente trabalho tem como principais objectivos analisar as concentrações e o comportamento dos metais pesados no solo; dar a conhecer alguns casos de contaminação e descontaminação do solo em Portugal, sendo os primeiros provenientes não só de actividades industriais e de resíduos mas também da indústria extractiva; analisar a legislação nacional e internacional (oriunda de Ontário, Holanda e Espanha) no âmbito da contaminação/remediação do solo por metais pesados; analisar as principais tecnologias e técnicas (in-situ e ex-situ) de reabilitação de solos contaminados; investigar um caso-estudo relativo à contaminação do solo por As, Cd, Cr, Cu, Hg, Ni, Pb, Zn de uma unidade fabril; analisar, a evolução destes elementos entre 1997 e 2007; e comparar os teores obtidos neste estudo com os teores considerados naturais e os teores da legislação, uma vez que é importante diferenciar as situações de concentrações elevadas como consequência da contaminação do solo de origem antrópica das concentrações “naturais” elevadas que resultam da assinatura geoquímica do material parental do solo (rocha-mãe). Os resultados mostraram concentrações máximas de 14mg/kg de As, 1mg/kg de Cd, 39mg/kg de Cr, 62mg/kg de Cu, 1,2mg/kg de Hg, 29mg/kg de Ni, 170mg/kg de Pb e 790mg/kg de Zn, maioritariamente no solo superficial, excepto no caso do Hg. O Zn, Pb, Cr e Ni são os elementos que se encontram presentes em maior número de locais com concentrações mais elevadas, nos parques de armazenamento de resíduos, no parque de armazenamento de bobinas, na zona de depósitos de óleos a granel e na zona da portaria de entrada dos funcionários. O Pb e o Zn são os únicos metais pesados presentes no solo que atingem concentrações acima do Intervention value, de Ontário, que representa um nível de qualidade do solo acima do qual existem riscos para a saúde humana e para o ambiente, e implica intervenção imediata, podendo optar-se por tratamento in-situ, ex-situ ou remoção para aterro. Optando-se por esta última hipótese, estes solos contaminados com Zn, devem ser encaminhados para aterro de inertes. O caso do Pb demonstra a problemática em utilizar metodologias internacionais para o estudo de contaminação de solos nacionais. Perante a legislação internacional, a concentração máxima de Pb é considerada como uma concentração “problemática” perante o valor de referência de Ontário mas é, ao mesmo tempo, considerado como um valor não preocupante perante a legislação de Holanda, Madrid e Catalunha.
The soil, as a natural resource, has a multiplicity of functions, so it is urgent and necessary to protect it from all sources of contamination. This work has as main objectives to analyze the concentration and behavior of heavy metals in the soil, make known some cases of contamination and decontamination of soil in Portugal, the first arising not only from industrial activities and waste but also from the mining industry; to analyze national and international regulations (from Ontario, Netherlands and Spain) in the framework of contamination/remediation of soil by heavy metals; to analyze the best technologies (in-situ and ex-situ) for the remediation of contaminated soils; to investigate a case-study about soil contamination by As, Cd, Cr, Cu, Hg, Ni, Pb, Zn in an industrial brownfield site, to analyze the evolution of these elements between 1997 and 2007; and to compare the concentrations obtained in this study with the background values and legal values, since it’s important to distinguish between situations of antropic contamination of the soil and the situations of 'natural' high concentrations that result geochemical signature from soil parental material (bedrock). The results showed maximum concentration of 14mg/kg (As), 1mg/kg (Cd), 39mg/kg (Cr), 62mg/kg (Cu), 1.2 mg/kg (Hg), 29mg/kg (Ni), 170mg/kg (Pb) and 790mg/kg (Zn), mainly in topsoil, except in the case of Hg. The Zn, Pb, Cr and Ni are the elements that are present in more locations with higher concentrations in the parks waste storage, the park storage reels, in the park of bul oils deposits and in the entrance of employee. Pb and Zn are the only heavy metals that reach concentrations above the Intervention values (from Ontario regulation) that represents a quality level above the ground which there are risks to human health and the environment, and requires immediate intervention, may choose to treat in-situ, ex-situ or to remove to a landfill. In the last option, these contaminated soils with Zn, should be sent to landfill for inert materials. The case of Pb demonstrates the problem of using international benchmarks for the study of soil contamination in Portugal. Under international laws, the maximum concentration of Pb in soils is regarded as a "problem" according with the Ontario regulations but at the same time is regarded as a not disturbing concentration under the laws of Netherlands and Spain.
The soil, as a natural resource, has a multiplicity of functions, so it is urgent and necessary to protect it from all sources of contamination. This work has as main objectives to analyze the concentration and behavior of heavy metals in the soil, make known some cases of contamination and decontamination of soil in Portugal, the first arising not only from industrial activities and waste but also from the mining industry; to analyze national and international regulations (from Ontario, Netherlands and Spain) in the framework of contamination/remediation of soil by heavy metals; to analyze the best technologies (in-situ and ex-situ) for the remediation of contaminated soils; to investigate a case-study about soil contamination by As, Cd, Cr, Cu, Hg, Ni, Pb, Zn in an industrial brownfield site, to analyze the evolution of these elements between 1997 and 2007; and to compare the concentrations obtained in this study with the background values and legal values, since it’s important to distinguish between situations of antropic contamination of the soil and the situations of 'natural' high concentrations that result geochemical signature from soil parental material (bedrock). The results showed maximum concentration of 14mg/kg (As), 1mg/kg (Cd), 39mg/kg (Cr), 62mg/kg (Cu), 1.2 mg/kg (Hg), 29mg/kg (Ni), 170mg/kg (Pb) and 790mg/kg (Zn), mainly in topsoil, except in the case of Hg. The Zn, Pb, Cr and Ni are the elements that are present in more locations with higher concentrations in the parks waste storage, the park storage reels, in the park of bul oils deposits and in the entrance of employee. Pb and Zn are the only heavy metals that reach concentrations above the Intervention values (from Ontario regulation) that represents a quality level above the ground which there are risks to human health and the environment, and requires immediate intervention, may choose to treat in-situ, ex-situ or to remove to a landfill. In the last option, these contaminated soils with Zn, should be sent to landfill for inert materials. The case of Pb demonstrates the problem of using international benchmarks for the study of soil contamination in Portugal. Under international laws, the maximum concentration of Pb in soils is regarded as a "problem" according with the Ontario regulations but at the same time is regarded as a not disturbing concentration under the laws of Netherlands and Spain.
Descrição
Orientação: Fátima Alexandra Remiz Pereira Africano ; co-orientação: Anabela Gonçalves Cruces
Palavras-chave
ENGENHARIA DO AMBIENTE, ENVIRONMENTAL ENGINEERING, ENGENHARIA DE SOLOS, SOIL ENGINEERING, METAIS, METAL, MESTRADO EM ENGENHARIA DO AMBIENTE