MONITORING, RISK ASSESSMENT AND DISTRIBUTION OF METALS IN FRESHWATER SEDIMENTS IN URBAN AREA WITH INCIPIENT EFFECTS OF ANTHROPOGENIC DISCHARGE
Metal loading. Partitioning. Pseudo total extraction. Sequential Extraction.
The discharge of pollutants such as heavy metals to water bodies can pose a risk to the aquatic ecosystem. Several anthropic activities can contribute to the discharge of metals, especially in urbanized areas. Aquatic sediments have a great capacity to retain heavy metals, being able to release them according to physicochemical changes in the environment. However, the capacity of retention and release of metals depends on the compositional and granulometric characteristics of the sediment. Thus, this is utilized sediments collected in the Extremoz Lake and Doce River, located in an urban area on the coast of the Brazilian Northeast, which had rapid growth. There are two main objectives: to assess the ecological risk of metals in the sediment and the influence of the composition and granulometry of the sediment on the distribution of metals and; to monitor temporal and spatial variations of bioavailable metals in the sediment. The first objective was addressed in Chapter 1 of the Qualification Exam, which investigates the hypothesis that sediment characteristics such as composition and particle size influence the distribution and availability of metals, also affecting the ecological risk that metals represent. The second objective will be discussed later when defending the dissertation. In this case, the hypothesis that will be investigated is that temporal and spatial variations of metals in sediments are controlled respectively by rainfall and sediment characteristics.