RESUMO
Open-air landfill's may be are considered as a potential source of human environmental exposure to chemical substances such as, polycyclic aromatic hydrocarbons and toxic metals. Due to possible availability of mercury in the environment caused by open landfill emissions, this study evaluates the spatiality and seasonality of macroinvertebrates, in particular shrimps (Macrobrachium amazonicum), exposure to mercury (Hg). Information regarding Hg accumulation in this crustacean may be important for the development of public policies aiming conservation and preservation of ecosystems surrounding landfills in Amazon, and around the world. Sampling occurred quarterly in the following months: November/2015; February/2016; May/2016 and; August/2016. In each of these months, three points were selected: P1, P2 and P3. The samples were processed via acid digestion and the quantification of metal was performed by inductively coupled plasma mass spectrometry. The average concentration of total mercury (T-Hg) was 24.565 ± 6.610 µg kg-1 wet weight, with minimum and maximum limits of 12.742 ± 11.367 (P3) and 35.509 ± 14.761 µg kg-1 wet weight (P1) in November/2015 and August/2016, respectively. The concentration of total mercury (T-Hg) in shrimps was different between points (p = 0.004) and months (p = 0.000). The T-Hg concentrations were significantly higher in May and August 2016, which corresponds to the dry season. The presence of landfills promotes large accumulation of T-Hg in the aquatic biota and represents a risk to human health. However, seasonal changes in T-Hg levels were observed. In the wettest period, bioconcentration factor levels decrease in aquatic organisms.
