ORGANOCLORATED AND ORGANOPHOSPHORUS PESTICIDES IN THE PELOTAS RIVER SEDIMENT

<div><p>ABSTRACT Aquatic sediments are widely used for the evaluation of anthropogenic contamination due to their ability to adsorb particles and contaminants, making them historical environmental archives. Therefore, the objective was to evaluate the contamination of the Pelotas River sediments, at the border between the states of Santa Catarina and Rio Grande do Sul, by organochlorine and organophosphorus compounds, determining the ecological risk. The evaluation was carried out with quarterly sediment collections in 8 points, totalizing four campaigns within one year, with the aid of the Peterson dredger. Among organochlorines, p'p'DDT stands out regarding environmental persistence, representing 53.23% of the contaminated samples, with values varying up to 0.158 ppb. As for the organophosphates, Methyl Parathion obtained larger representation with 48.4% of the contaminated samples, with concentrations ranging up to 2.42 ppb. The ecological risk of selected organochlorines demonstrated no problems associated with the biota. Regarding the organophosphates studied, Disulfoton presented a risk factor with significant potential for adverse effects on organisms. Therefore, the need for monitoring and sustainability in the use and application of pesticides is well known, aiming at environmental quality and the preservation of natural resources.</p></div

MERCURY IN THE SEDIMENT OF PELOTAS RIVER BASIN, BRAZIL

<div><p>ABSTRACT Many studies have determined the concentration of trace elements in river sediments in Brazil. Notwithstanding, mercury assessments are scarce, especially because of exclusive extraction techniques and expensive analysis techniques. Still, this element is known for its toxicity, persistence, and bioaccumulation, making its presence in the environment an important factor for biota and human health. For this reason, the objective of this study was to determine the mercury concentration in the sediment of the Pelotas River basin, located on the border of the states of Santa Catarina and Rio Grande do Sul. The sediment was collected at eight locations of the Pelotas basin and, after drying, the mercury was quantified by atomic absorption spectrometry based on the Zeeman-background correction, coupled to a pyrolysis reactor. The mercury concentrations in the sediments of the Pelotas River varied from 40.5 ng g-1 to 62.0 ng g-1 and presented a positive correlation with the fraction of silt and clay. The concentrations of mercury found in sediments of the Pelotas River basin have a low probability of negatively affecting the biota. Nonetheless, given the persistence and bioaccumulation potential of this element, the aforementioned region needs further studies to quantify the risks it may cause on the local biota and human health.</p></div