ABSTRACT The contamination of aquatic environments with chemical trace elements can be evaluated by their accumulation in sediments of the water body. Studies on mercury require the use of exclusive extraction techniques that have relatively high costs when compared to the analysis of other trace elements. This study was conducted aiming at determining the mercury concentration in sediments of the Upper Parnaíba River basin, located in a region of agricultural expansion between the states of Piauí and Maranhão. The sediment was collected at 12 sites in the basin. After drying, the quantification of total mercury was performed by the Zeeman atomic absorption spectrometry coupled to a pyrolysis reactor. Mercury concentrations in sediments of the Parnaíba River ranged from 4.2 to 58.5 ng g−1 and presented a low probability of adverse effects on biota. Mercury had no correlation with the variables clay, silt, sand, total organic carbon, iron, and aluminum, demonstrating its possible anthropogenic origin. Although mercury concentrations have a low probability to disturb the balance of the local ecosystem, there is a need for monitoring the region in order to quantify the risks to biota and human health.

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.

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.

Os resíduos gerados em suinoculturas possuem alto potencial poluidor, porém, devido à grande carga orgânica, apresenta-se como boa opção na fertilização de solos agrícolas. O objetivo deste trabalho foi estudar os efeitos ambientais decorrentes do uso de águas residuais de suinocultura em diferentes solos usando como bioindicador minhocas da espécie Eisenia andrei, por meio dos parâmetros de letalidade, fuga e reprodução. Estudou-se a aplicação de água residual de esterqueira e biodigestor em quatro doses (0, 100, 200 e 300 m³ ha-1) em três solos: Latossolo Vermelho distroférrico típico, Nitossolo Vermelho eutroférrico e Solo Artificial Tropical. Os resíduos estudados não provocaram qualquer letalidade nem fuga. Nos testes de reprodução, na maioria dos experimentos as parcelas com tratamentos obtiveram valores médios de juvenis eclodidos acima das parcelas controlo. A aplicação de água residual de esterqueira e biodigestor até a dose de 300 m³ ha-1 não afeta negativamente as populações de minhocas nos três solos analisados.

The waste generated by pig farmings has high toxic potential, however, its high organic load, makes them a good product for fertilization of agricultural soils. The aim of this work was to study the environmental effects arising from the use of swine wastewater using as bioindicators earthworms of the species Eisenia andrei through the parameters of lethality, avoidance and reproduction. We studied the application of biodigester wastewater and manure storage tanks wastewater in four doses (0, 100, 200 and 300 m³ ha-1) in three different soils (Oxisol, Kandiudox and Artificial Tropical Soil). The studied wastes did not cause any lethality or escape. The reproduction test showed, in most of the experiments that the plots with treated soil had an average number of hatched juveniles above those of control plots. The application of biodigester wastewater and manure storage tanks wastewater up to the dose of 300 m³ ha-1 does not negatively affect earthworm populations in the three soils analyzed.