The goal of this work was to study quantitatively lead bioaccumulation from a leaddoped nutrient medium by using a living aquatic macrophytes Pistia stratiotes. Several sets of aquatic plants with approximately 30 g weight were grown in greenhouse conditions and in hydroponic solutions supplied with a non-toxic Pb 2+ concentration. The synchrotron radiation total X-ray fluorescence spectrometry was used to determine the metal concentrations in dry plants and hydroponic media as a function of time. Four different non-structural bioaccumulation models were applied to describe the process dynamics and to estimate the accumulated lead maximum capacity and rate constants. According to the experimental data, both biosorption and bioaccumulation mechanisms can be considered. Due to the low desorption rate constant, the experimental data were well described by the irreversible kinetic model. The results concerning modeling of living macrophytes' metal bioaccumulation kinetics can be used to predict the heavy metal removal dynamics from wastewaters in artificial wetlands.

Lately, the identification of emerging pollutants in environmental matrices has become frequent. Among these pollutants, the presence of drugs is highly relevant, because these categories of contaminants comprised thousands of active substances highly consumed worldwide. In the last decades, there has been a significant increase in the prescription and consumption of neuroactive drugs, such as antidepressants, and due to their direct action on the nervous system, neuroactive drugs are cited as a major environmental concern. Several studies have reported the presence of neuroactive drugs in wastewater treatment plants, surface waters, sediments and tissues of aquatic organisms. Environmental research involving drugs are linked to their low biodegradability and its persistence in the environment, with the potential risk of ecotoxicological effects. This paper reviews the literature related to environmental occurrence of pharmaceuticals, focusing on antidepressants incidence as well as their effects on non-target organisms. Moreover, it contributes to the scientific literature addressing the most widespread analytical techniques in this research field as well as the need for more comprehensive studies focused in detection, destination, distribution and elucidation of the likely effects caused by residual drugs in the environment.

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The recently developed nitrene transfer reaction onto gold‐activated alkynes provides a route to safe and accessible synthons of α‐diazo imides. This reaction is rather unique in that it requires AuI in catalytic amounts; however, this promiscuous metal is only used to activate the alkyne moiety. After such activation is obtained, the nitrene‐transfer process occurs through an outer‐sphere mechanism, in which the metal acts only as a spectator. Density functional theory was applied to elucidate this peculiar reaction and to provide a mechanistic explanation for the experimentally observed isomers at the double bond and imine sites.

Introdução: O descarte indevido de medicamentos é consequência de uma série de fatores, entre eles o fácil acesso a medicamentos, falta de fiscalização sanitária, leis fracas e falta de conhecimento da população sobre os riscos envolvendo os contaminantes ambientais contidos em formulas farmacêuticas. O sistema fraco de regulamentação e normas de orientação ao comercio e aos consumidores são insuficientes para minimizar os riscos e prejuízos decorrentes do descarte incorreto em lixo comum ou nas redes de esgotamento

Sediments are reservoirs for a variety of substances widely used as indicators of pollution in aquatic environments. In this research was carried out the evaluation of the concentration of metals in the pseudo-total and labile fractions in surface sediments at the mouth of four main tributaries of the Itaipu Reservoir. Three samplings were performed between February 2014 and March 2015 using Petersen type dredger. The determination of metals occurred by atomic absorption spectrometry and physical-chemical parameters by gravimetric and potentiometric techniques. The samples presented neutral to slightly alkaline character and homogeneous pHs. It was observed the predominance of the clay fraction and the occurrence of variable organic matter between the points. In the labile fraction, only the copper content reached concentrations higher than the thresholds effects levels (TEL) at all sampling points. In the pseudo-total fraction, some sites presented for Cr, Pb and Zn TEL level. For Ni, values of probable effects level (PEL) were verified and for Cu, concentrations in severe effect level (SEL) were reported according to the international sediment classification criteria adopted by the National Oceanic and Atmospheric Administration (NOAA).