Analysis of metals in the sediment in the bay of Guajará Belém/PA

Abstract

It is important to maintain the quality of the water bodies, since it plays a significant role for the aquatic ecosystem and population. In the bay of Guajará in Belém/PA, it is no different, it plays an important role for aquatic organisms and exerts a considerable economic influence on the state. However, its quality is being impaired due to the changes caused by natural and/or anthropic activities. Environmental assessment through sediment studies (bottom and suspension) has been highlighted as a means to evaluate the environmental conditions of a water body, since it plays the role of accumulating, reprocessing and transferring the chemical elements present in this natural resource, quantify the degree of pollution of a given site and check for possible contamination of water and aquatic organisms with time. It is necessary to carry out detailed studies of river sediments in order to know the origins and the level of contamination that the environment is being affected. Thus, the study analyzed the Cr, Cd, Cu and Fe metals in the bottom sediment, in the total form and leached in Guajará bay, Belém / PA, calculating the FC, I_geo and FE, in order to verify the degree of contamination of the sediment, the origin of this pollution, and thus obtain a diagnosis of the research site. The study was performed in 4 points (PT01, PT02, PT03 and PT04). The collections occur in the year 2015 and 2016, in distinct seasonal periods (rainy and less rainy). The samples were collected with Van Veen dredges. The process of acid digestion and leaching of the collected sediment was carried out. The metals were quantified by the technique of Optical Emission Spectrometry with Induced Coupled Plasma (ICP OES). In the analysis of the total sediment, the Cd presented values ​​above that allowed by PEL and CONAMA nº 454/2012, already in the leached phase, all metals were within the allowed by the legislation. In general, the points presented low to moderate contamination, characterized as an unpolluted environment to a moderately polluted and enriched deficiency. Continuous monitoring of the Guajará Bay is necessary since the concentration of contaminants in the sediment can reach values ​​that cause damage to aquatic biota, and this also endangers the health of the human population, considering that the contamination process can begin in the sediment and reach the highest levels of the food chain.