Modelo Integrado para a Avaliação da Exposição Ambiental a Resíduos Mineiros Radioactivos

• Type: Thesis
• Date: 2000

Authors

Maria de Lurdes Proença de Amorim Dinis (Author) FEUP; António Fiúza (Technical adviser) FEUP

Scientific classification

FOS: Natural sciences

CORDIS: Natural sciences ; Natural sciences > Environmental science ; Physical sciences

Associated Institutions

FEUP - Faculdade de Engenharia da Universidade do Porto

Other information

Resumo (PT): O principal objectivo deste trabalho é desenvolver um modelo global paramétrico de avaliação das doses externas e quantificação do risco gerados por uma barragem de estéreis de resíduos do tratamento hidromineralúrgico do minério de urânio. O modelo apresentado é constituído por vários sub-modelos parcelares retirados da bibliografia consultada, adaptados, em alguns casos, aos propósitos. Procedeu-se à agregação destes sub-modelos de forma a constituírem um modelo conceptual coerente. O modelo contempla a estimativa da dispersão ambiental dos contaminantes originada pela acção de transporte exercida pelos vectores dispersivos, quer no meio atmosférico, quer no meio hidrológico. A exploração do modelo foi feita com os parâmetros adoptados da bibliografia consultada e parcialmente com dados disponíveis de um local concreto, a barragem de estéreis da Oficina de Tratamento de Minérios da Urgeiriça. Os resultados da simulação são expressos segundo a via de exposição a que os seres humanos podem estar expostos: inalação, ingestão, submersão na pluma de contaminação atmosférica e irradiação directa do solo contaminado.

Abstract (EN): In the past, when confinement of mining wastes was not obligatory, large volume of residues were disposed off in open-air tailings. Erosion agents, specially wind and water, as well as biological processes provoked the dispersion of toxic elements in the environment. Dispersion in the environment by natural agents can affect large areas. We propose a methodology for evaluating the risk assessment resulting from such dispersion, which includes, besides a global transfer model, some particular and restricted sub-models of transfer and fate. Dispersion of elements from wastes is done by three main transport mechanisms: liberation of waste dusts into the air, transport as suspended solids in run-off waters and transport by run-off or by infiltration into underground water. Release mechanisms can be originated by chemical or biochemical leaching. Dust transported by air can be deposed in plants or soil or can be inhaled by animals and humans originating a direct exposure. Part of dust can be incorporated into the vegetation by folliar absorption. Infiltrated water with dissolved toxic elements can reach wells, springs and streams and be dispersed by superficial waters. Runoff waters will carry both particles of wastes and dissolved toxic elements. This transport path will affect the sediments (adsorption) and soil and will have the aquatic plants and animals as direct receptors, and man by direct ingestion. Soil may affect plants (uptake by the roots), cattle by direct ingestion and superficial waters by erosion. Plants can be directly ingested both by animals and man. Aquatic biota can be affected both by uptake and adsorption from surface water or sediments. Man can be directly exposed through inhalation, ingestion and dermic contact or indirectly by plants, animals and by fish and aquatic birds.

Language: Portuguese

Type (Professor's evaluation): Scientific

No. of pages: 167