Heavy metals in the soils of Tallinn (Estonia) and its suburbs
1993; Taylor & Francis; Volume: 11; Issue: 3-4 Linguagem: Inglês
10.1080/01490459309377958
ISSN1521-0529
Autores Tópico(s)Radioactivity and Radon Measurements
ResumoGeochemical investigations aimed at an estimation of the anthropogenic load in natural ecosystems and the accumulation and redistribution of microelements are very important for heavy industry. In geochemical mapping of the territory of Tallinn, the biggest industrial center of Estonia, and of its suburb Maardu, two very substantial geochemical anomalies with high levels of several microelements were discovered. Relative to natural background, the concentrations of Pb, Zn, Cu, Mn, Ni, and Cr were significantly elevated. Consecutive chemical extraction of soil samples distinguished seven forms in which each element may exist in soil with the potential for migration. For all elements a balance of different forms of migration from the upper and lower horizons was established. A correlation of the amounts of the migration forms with the granulometric composition of the soils was sought. It was discovered that concentration of Cu and Zn took place in the upper horizon, mostly as sulfides and in the adsorbed state. Accumulation of Pb and Mn occurred mainly in the form of carbonates. In these forms, elements were rather mobile and capable of redistribution and accumulation. Up to 70–80% of the total amount of Cr and Ni in the soil occurred as freely and sparingly soluble silicate minerals. Lead, Zn, and Cu are ecologically the most harmful among the microelements because they can be easily absorbed by plants and participate in biogeochemical cycles.
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