Phytoremediation of uranium contaminated soils

Abstract

Environmental uranium contamination based on human activity is a serious problem worldwide. Soil contaminated with uranium poses a long-term radiation hazard to human health through exposure via the food-chain and other pathways. This chapter is an overview of processes and modern techniques for remediation of soils contaminated with uranium, with special attention on phytoremediation. Phytoremediation takes advantage of plant to extract, sequester pollutants in soil, water, and air with an aim of pollutant removal and transformation into harmless forms.The objective of this chapter is to develop a better understanding of plants behavior and the degree of affinity towards the adoption of uranium for hyperaccumulators plants based on review of international research. To understand the mechanism of uranium uptake in plants and accumulation, a necessary prerequisite is the application of radiophytoremediation on the "real" scale. For this purpose, we investigated these processes using three different aspects with selected cultivated plants: 1. Vegetative tests in pots of fully controlled conditions, with corn plants that were grown on two types of soil, pseudogley and chernozem, together with its phytotoxic effect on the plant development, height, yield, and seed germination.2. Greenhouse experiments with tailings from the closed uranium mine Kalna on the southeast of Serbia. Three series of experiments were conducted in plastic-house. First, three plant species (corn, sunflower, and green peas) were grown in pots on the four substrate variants, tailings in mixture with sand. The substrate was irrigated with drinking water and "uranium water", which issues out from the mine. Another experiment was conducted in order to investigate the uptake of U in several kinds of roots-crops, bulbous, and tuberous plants: carrot, onion, potatoes, radish, red beet, and sugar beet. Content of uranium was found in leaves and roots (surface root layer and edible parts were peeled). Also we investigated uranium adoption in four genotypes of com, sunflower, and soy bean.3. Vegetation test on real, native conditions on tailings, from the closed uranium mine Kalna. The experiment was carried out on the elementary plots one square meter in size, with bean, cabbage, lettuce, com, onion, potatoes, spinach, and sunflower.Well-organized use of phytotechnology means an integrated management strategy for contaminated sites which include proper selection of plants (uranium hyperaccumulators), improving mobility of uranium with amendments (organic agents), and application sequestering agents for immobilization and transformation of excess uranium, which the plants didn't accept.