CONTAMINAÇÃO POR METAIS PESADOS EM SEDIMENTOS, ÁGUA E PEIXES DE RIOS DO ESTADO DE MATO GROSSO DO SUL: AVALIAÇÃO DE RISCO ECOLÓGICO E IMPLICAÇÕES PARA A SAÚDE HUMANA

Abstract

This study aimed to quantify the concentration of macro and microelements in water, sediments, muscle of curimba fish (Prochilodus lineatus) and catfish (Pimelodus maculatus) from the rivers Anhanduí, Rio Pardo and Ribeirão da Lontra in MS/Brazil, as well as assess the ecological and human health risks due to contamination by heavy metals. Digestion of the samples was performed using microwaves. Chemical elements were quantified by inductively coupled plasma optical emission spectrometry (ICP OES). The spatial distribution of heavy metals in water was performed using principal component analysis (PCA). Sediment contamination was evaluated based on the geoaccumulation index (Igeo), contamination factor (FC), pollution load index (PLI) and enrichment factor (EF). Estimation of carcinogenic and non-cancerous risk was investigated for adults based on eating 450 g of fish per week. The PCA analysis based on the concentration of heavy metals in water samples showed a spatial distribution pattern with a greater tendency for the elements Cu, Ni, Cu, N, Co, As, Hg, Al and Al and Co in L1 and Cr, Pb in L2. According to the Igeo classification, the five collection sites have sediments practically unpolluted by Co, Cr and Cu. On the other hand, sites like L1, L2 and L3 are classified as unpolluted to moderately polluted for Cu. For river sediments, the Igeo varied between 4-5, that is, they are heavily to extremely polluted, including L1, L2, L3, L4 and L5 by Mo and L1, L2, L4 and L5 by Cd in the first collection. One year after the first collection, locations such as L1, L2, L3, L4 and L5 were classified by Igeo as extremely polluted by Cd, which may indicate the anthropic influence on the quality of the rivers. The FC results demonstrate that the collection points in the rivers have variable characteristics, where they presented a low contamination factor by Co and Cr, however, moderate contamination by Cu, As, Co, Ni and Pb. However, elements such as Cd and Mo showed a very high contamination in the sediment of all analyzed rivers. The level of pollution load index (PLI) of the sediment in the studied rivers showed a local deterioration and the EF values indicated that Cd was the element that most contributed to the enrichment among the analyzed heavy metals. With the exception of the data found at the L4 site, the values of As are above the Rd when consumed by children, however, they are also above the Rd when consumed by adults at the L2 (C2), L3 and L5 (C1) sites. The Average Daily Dose (ADD) of Cr was higher than the Rd for both adults in all collection sites. The ADD of metals was above the Rd for As, Cr and Cd in all collection sites when curimba fish is consumed by children, representing a threat to health. Consumption of catfish and curimba fish may pose a non-carcinogenic risk to adults, mainly in relation to exposure to As and Cd, with Cd representing most of the potential cumulative risk with HI > 1 in all locations of the sampled rivers. The elements As, Cd and Cr presented carcinogenic risk (CR) for adults with values greater than 1 x 10-4, while Cu and Pb presented values within the acceptable risk. This study revealed that the studied rivers must suffer anthropic action because the concentration of heavy metals pose an ecological, non-carcinogenic and carcinogenic risk.