Metais e seus efeitos em baixos níveis de organização biológica: uma análise ecotoxicológica em distintos compartimentos ambientais de igarapés no município de Barcarena/PA.

Abstract

Metals are included among the contaminants that influence the dynamics of aquatic ecosystems, which requires studies aimed at evaluating both the concentrations of these elements and possible toxicity effects on aquatic organisms due to bioavailability. In this context, biomonitoring studies, especially involving ecotoxicological variables, related to responses, at a low level of biological organization are useful to assess environmental quality. The present ecotoxicological study includes three approaches: (1) analysis of the concentration of metals in Al, Cr, Pb, Ba, Ni and Mn in abiotic elements (water and stream sediment); (2) biotic compartments (fish - Hyphessobrycon heterorhabdus; crab - Trichodactylus borellianus and vegetable a plant species Family Marantaceae), in addition to the (3) assessment of primary adverse effects through the use of exposure and effect biomarkers. The collections were carried out in the area of the hydrographic network that influences the Murucupi Basin, in the communities Bom Futuro, Vila Nova and in the district of Vila do Conde and were carried out in three climatic periods, namely: Dry (Campaign 1: Nov/2018), Rainy (Campaign 2: Mar/2019) and Transition period (Campaign 3: Jun/2019). The collection points were determined in order to contemplate a gradient of influence from the company's activity and from other types of activity that take place in the region. The points were dispersed as follows: Potential direct impact (PM1, PM2, PM3, PM4 and PM5); Potential indirect impact: (PC2, PC3 and PC5); and Control points: (PC1, PC6, PC7, PC8 and PC9). The species were collected in different streams that are located in a region with a history of bauxite processing activity (Barcarena, PA), in addition to the direct anthropogenic influence of the city. The collections were carried out in the area of the hydrographic network that influences the Murucupi Basin, in the communities Bom Futuro, Vila Nova and in the district of Vila do Conde and were carried out in three climatic periods, namely: Dry (Campaign 1: Nov/2018), Rainy (Campaign 2: Mar/2019) and Transition period (Campaign 3: Jun/2019). The collection points were determined in order to contemplate a gradient of influence multiple anthropogenic influences. The points were dispersed as follows: Potential direct impact (PM1, PM2, PM3, PM4 and PM5); Potential indirect impact: (PC2, PC3 and PC5); and Control points: (PC1, PC6, PC7, PC8 and PC9). In general, in the sediment of the streams, the analysis of metals presented a distribution within the same range in terms of measured concentrations, without significant differences between sampled points and between sampling periods. For the in-water analyses, during the three periods there was a distribution within the ranges according to the terms of measurements. There was no significant increase or decrease for the elements studied, among the metals analyzed, only Al (total fraction) is not mentioned in CONAMA Resolution No 357/2005. All others are below the acceptable limit established by the environmental protection agency. The only metal that showed an increase in concentration between campaigns in the total fraction of water was Ba. Al was the most abundant metal with concentrations that did not differ between periods. For organisms, fish collected showed higher concentrations of Al and Ba in the rainy season compared to fish of the same species collected in the dry season. The metals Al and Mn did not show differences between points in the same period. Pb was recorded in higher concentrations during the dry season. Plants also did not show significant differences neither between points nor between periods for any of the metals, however, they showed a tendency to increase the accumulation of Pb, Mn and Ba during the transition period. As for the evaluation of biological responses using exposure and effect biomarkers, in crabs there was induction of antioxidant defenses in the gills of organisms from point PC1 during the rainy season. The fish H. heterorhabdus showed greater antioxidant capacity for organisms from PC07 during this period. It is concluded that there is a well-marked and seasonal pattern of metals in different environmental compartments that are followed by biomarkers, reflecting changes related to local geology and physiology of organisms. The main metals found in the abiotic (water - total and dissolved fraction and sediment) and biotic (fish, invertebrates and plant) compartments showed a strong relationship with the local geological formation, with Al, Ba and Mn being the most representative. Being, the Al the most concentrated. Therefore, based on the results described here, studies are needed to establish environmental baselines that take into account local chemical and physical characteristics and the level of sensitivity / tolerance of resident organisms. These studies will lay the groundwork for establishing applicable legal restrictions that are compatible with local environmental realities.