RESUMO
Contamination of aquatic ecosystems by potentially toxic elements (PTEs) is a concerning environmental issue, given their persistence, toxicity potential, and ability to accumulate in living organisms. Several studies have been conducted to assess the contamination of aquatic ecosystems by PTEs, using pollution and ecological risk indices that rely on the concentration of these elements in aquatic sediments. However, many of these studies use global reference values for calculating the indices, which can lead to misleading interpretations due to substantial variations in PTEs concentrations influenced by the geological characteristics of each region. Therefore, the use of regional reference values is more appropriate when available. This study aimed to investigate variations in the results of five indices, employing global, regional, and quality reference values, based on sediment samples collected from rivers in the Ipanema National Forest, a protected area in Brazil exposed to various anthropogenic pressures. The results revealed that elements such as Al, Fe, and Mn exceeded the limits allowed by legislation in water samples, while As and Cr surpassed the limits in sediment samples. Comparative analysis highlighted significant discrepancies in the results of the indices when global reference values were used compared to regional and quality reference values, especially for As and Ba. Thus, this study underscores the importance of establishing specific regional values for an accurate assessment of sediment quality and the risks associated with contamination by PTEs in different regions worldwide.
Assuntos
Conservação dos Recursos Naturais , Ecossistema , Brasil , Valores de Referência , Poluição AmbientalRESUMO
Urban rivers are affected at different levels by the intensification of human activities, representing a serious threat to the maintenance of terrestrial life and sustainable urban development. Consequently, great efforts have been dedicated to the ecological restoration of urban rivers around the world, as a solution to recovering the environmental functionality of these environments. In this sense, the present work aimed to investigate the effectiveness of interventions carried out aimed at the recovery of urban rivers, through a systematic review of the literature between 2010 and 2022, using the search term "rivers recovery." The results showed that there have been notable advances in the implementation of river recovery programs in urban areas around the world between the years analyzed. The ecosystems studied were affected, for the most part, by the increase in the supply of nutrients from domestic and industrial effluents, in addition to having highly urbanized surroundings and with several changes in land use patterns. The preparation of this literature review made it possible to demonstrate that the effectiveness of river recovery is extremely complex, since river recovery projects are developed for different reasons, as well as being carried out in different ways according to the intended objective.
Assuntos
Rios , Rios/química , Ecossistema , Recuperação e Remediação Ambiental/métodos , Humanos , Conservação dos Recursos NaturaisRESUMO
Trace and potentially toxic elements represent one class of food contaminants that has stimulated research. In markets, two main methods of growing vegetables are generally available: conventional and organic. Conventional farming has been the target of some concerns about the use of agrochemicals, especially the excessive use of pesticides, whereas organic agriculture minimizes the use of agrochemicals. As the main route for potentially toxic elements' absorption by humans is by food intake, it is important to evaluate if the method of cultivation influences their concentrations. This study evaluated the levels of potentially toxic elements and nutrients on four leafy vegetables: curly lettuce, collard greens, escarole, and rocket, cultivated by conventional and organic farming. We found that Al, Ba, Fe, and Sr levels were higher in conventional samples, whereas K, Pb, and Zn were higher in organic. Amongst the elements analysed, values of Fe, Al, and K were around 0.2, 0.3, and 70 g kg-1, respectively, except in collard greens, in which the values were lower. On the other hand, Ba, Sr, and Mn presented higher concentration in collard greens compared to the other vegetables in conventional cultivation (~ 35, 80, and 120 mg kg-1, respectively). The principal component analysis result shows that the samples were grouped according to the type of vegetable, regardless of the type of cultivation. Despite this, the evaluation of the cultivation by different types of farming is important in order to choose the healthiest option.
Assuntos
Monitoramento Ambiental , Verduras , Agroquímicos , Humanos , Lactuca , Folhas de PlantaRESUMO
Potentially toxic elements (PTEs) constitute a class of metals, semimetals, and non-metals that are of concern due to their persistence, toxicity, bioaccumulation, and biomagnification in high concentrations, posing risks to the ecosystem and to human health. A systematic literature review (SLR) was used in this study to identify natural and anthropogenic sources of PTEs for the aquatic environment. The databases consulted were ScienceDirect, Scopus, and Web of Science, in the period 2000-2020, using specific terms and filters. After analyzing the titles, abstracts, and full texts, 79 articles were selected for the SLR, in which 15 sources and 16 PTEs were identified. The main anthropogenic sources identified were mining, agriculture, industries, and domestic effluents, and the main natural sources identified were weathering of rocks and geogenic origin. Some places where environmental remediation studies can be carried out were highlighted such as Guangdong province, in China, presenting values of Cd, Cr, and Cu exceeding the national legislation from drinking water and soil quality, and Ardabil Province, in Iran, presenting values of As, Cr, Cu, Ni, Zn, and Pb exceeding the standard for freshwater sediments of USEPA, among others places. With the results exposed in this work, the government and the competent bodies of each locality will be able to develop strategies and public policies aimed at the main sources and places of contamination, in order to prevent and remedy the pollution of aquatic environments by potentially toxic elements.
Assuntos
Metais Pesados , Poluentes do Solo , China , Ecossistema , Monitoramento Ambiental/métodos , Humanos , Metais Pesados/análise , Medição de Risco , Solo , Poluentes do Solo/análiseRESUMO
Iron is an essential mineral and one of the most abundant in soils, presenting itself in the environment as ferrous and ferric ions. As each oxidation state of iron has a different role in the environment, its speciation in environmental studies is important. The determination of ferrous iron received great attention from soil chemists because of its important role in agriculture, in redox processes, and as an electron acceptor in the catalysis of organic matter. Methodologies with the use of colorimetric reagents to determine ferrous iron are divergent and not very clear. In this study, we compared two colorimetric reagents (1,10-phenanthroline and ferrozine) to determine the total concentration of iron, ferrous and ferric ions in soil, using simple and low-cost methodologies. The determination of ferrous and total iron with 1,10-phenanthroline colorimetric reagent, following published instructions, did not correlate with ferrozine method, presenting an erroneous quantification. After neutralizing the extract of 1,10-phenanthroline with NaOH, both colorimetric methods allowed to quantify with precision and high yield the amount of ferrous and total iron extracted from the soil. The oxidation states of iron have a different contribution and importance to the environment. In this sense, the improvement of a widely used methodology is crucial for the better study of iron speciation in soil.
Assuntos
Ferro , Solo , Monitoramento Ambiental , Compostos Férricos , Compostos Ferrosos , Ferro/análise , Minerais , OxirreduçãoRESUMO
Aquatic contamination by potentially toxic metals is a problem that has been aggravated, especially due to the quantity and the diversity of sources. Locating these sources is not always an easy task, especially because of the wide variety of possibilities. In this context, the application of geostatistical methods may represent an excellent tool to find out sources of metal contaminants in aquatic systems. Thus, the objective of this work was to elaborate an approach to identify sources of potentially toxic metals (Zn, Ba, Pb, Cr, Mn and Fe), by relating their spatial-temporal variations with the local land use patterns, along a longitudinal profile of the Pirapora River, located in the State of Sao Paulo, Brazil. For this purpose, water samples were collected at different points, taking into consideration each specific land use pattern and quantifying the metals contents by microwave plasma atomic emission spectrometry. In this work, thirteen land use patterns have been identified: mining, forestry, abandoned pasture, water, urban area, human occupation, floodplain, bare soil, temporary crop, roads, forest, streets and pasture. The results revealed temporal variations for the metals Ba, Cr, Fe, and Pb and spatial for Zn and Mn, making possible to correlate the presence of these two latter metals with mining and forestry, the most proeminent activities in the region. Overall, this work proposes a model which brings together geoprocessing and analytical methods, in order to correlate spatial-temporal variations of potentially toxic metals with specific land use patterns of a determined region, aiming the environmental monitoring.
Assuntos
Monitoramento Ambiental/métodos , Metais Pesados/análise , Modelos Teóricos , Poluentes Químicos da Água/análise , Agricultura , Brasil , Florestas , Humanos , Metais Pesados/toxicidade , Mineração , Rios , Solo/química , Análise Espaço-Temporal , Poluentes Químicos da Água/toxicidadeRESUMO
The contamination of aquatic and terrestrial environments by potentially toxic metals is highlighted by the possible impacts that their high availability can have on the environment. Thus, the development of alternative absorbents that can be used in the remediation of contaminated areas is of great environmental interest. Humin, one of the fractions of natural organic matter, is a promising alternative in studies on the retention of different metals that are environmentally toxic. In this study, the influence of the organic and inorganic humin constituents that are involved in the retention of aluminum species was evaluated. After extraction and calcination to obtain the ashes (inorganic constituents), humin and ash samples were structurally characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Interaction studies between aluminum-humin and ash-humin were performed in the pH range of 4.0-8.0 and with various contact times. The results of the characterization of humin and ash showed different functional groups present in the structures of these materials. Based on the results of the interaction between humin-aluminum and ash-aluminum, it can be inferred that both the organic and inorganic components of humin are efficient at absorbing aluminum. However, the adsorption isotherms showed that humin and the ashes have different adsorption behaviors. Humin is the only fraction of natural organic matter with a significant inorganic constituent content; it is the fraction least used by researchers in this field and is often discarded as waste. In light of this, the results obtained in this work highlight the importance of humin as a natural adsorbent material. Humin may be promising for the removal of aluminum species in contaminated environments due to the presence of organic and inorganic constituents.
Assuntos
Alumínio/química , Purificação da Água , Adsorção , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
One of the waste products of the industrial process of the sugar and alcohol agribusiness is filter cake (FC). This waste product has high levels of organic matter, mainly proteins and lipids, and is rich in calcium, nitrogen, potassium and phosphorous. In this work we characterized samples of FC from sugar and alcohol industries located in sugarcane-producing regions in Brazil and assessed the adsorption of potentially toxic metals (Cu(II), Cd(II), Pb(II), Ni(II) and Cr(III)) by this waste in mono- and multi-elemental systems, seeking to use FC as an adsorbent in contaminated environments. The characterization of FCs showed significant differences between the samples and the adsorption studies showed retention of over 90% of potentially toxic metals. In a competitive environment (multi-metallic solution), the FC was effective in adsorbing all metals except lead, but less effective compared to the mono-metallic solution. These results show the potential for use of this residue as an adsorbent in contaminated environments.
Assuntos
Filtração , Indústria de Processamento de Alimentos , Resíduos Industriais/análise , Metais Pesados/química , Gerenciamento de Resíduos/métodos , Resíduos/análise , Adsorção , Brasil , Carboidratos , Etanol , Gerenciamento de Resíduos/instrumentaçãoRESUMO
The effect of competition of Cu(II) and Ni(II) on the kinetic stability of Cr(III) complexed with natural organic matter (NOM) was characterized using EDTA exchange with single-stage tangential-flow ultrafiltration. For a water sample from Serra de Itabaiana, 3% of spiked Cr(III) was exchanged, while for a sample from the Itapanhaú River, 7, 10, 10, and 21% was exchanged in experiments using Cr(III) alone and in combination with Cu(II), Ni(II), or Cu(II) + Ni(II), respectively. Times required to reach exchange equilibrium with EDTA were less than 360 min. The influence of competition from Ni(II) and Cu(II) on the availability of complexed Cr(III) was low, demonstrating preference of the ligand sites for Cr(III). This was correlated with sample humification, as confirmed by EPR and (13)C NMR analyses. Exchange efficiency was in the order Cu > Ni > Cr, and the process could be readily described by first order kinetics, with average rate constants of 0.35-0.37 h(-1).
Assuntos
Cátions/química , Ácido Edético/química , Metais Pesados/química , Poluentes Químicos da Água/química , Cromo/química , Cobre/química , Humanos , Troca Iônica , Cinética , Ligantes , Níquel/química , Termodinâmica , UltrafiltraçãoRESUMO
Agrochemicals are amongst the contaminants most widely encountered in surface and subterranean hydrological systems. They comprise a variety of molecules, with properties that confer differing degrees of persistence and mobility in the environment, as well as different toxic, carcinogenic, mutagenic and teratogenic potentials, which can affect non-target organisms including man. In this work, alginate/chitosan nanoparticles were prepared as a carrier system for the herbicide paraquat. The preparation and physico-chemical characterization of the nanoparticles was followed by evaluation of zeta potential, pH, size and polydispersion. The techniques employed included transmission electron microscopy, differential scanning calorimetry and Fourier transform infrared spectroscopy. The formulation presented a size distribution of 635 ± 12 nm, polydispersion of 0.518, zeta potential of -22.8 ± 2.3 mV and association efficiency of 74.2%. There were significant differences between the release profiles of free paraquat and the herbicide associated with the alginate/chitosan nanoparticles. Tests showed that soil sorption of paraquat, either free or associated with the nanoparticles, was dependent on the quantity of organic matter present. The results presented in this work show that association of paraquat with alginate/chitosan nanoparticles alters the release profile of the herbicide, as well as its interaction with the soil, indicating that this system could be an effective means of reducing negative impacts caused by paraquat.
Assuntos
Portadores de Fármacos/química , Nanopartículas/química , Paraquat/química , Solo/química , Adsorção , Alginatos , Quitosana , Portadores de Fármacos/síntese química , Ácido Glucurônico , Herbicidas/química , Ácidos Hexurônicos , Tamanho da Partícula , Solo/análise , Poluentes do SoloRESUMO
Improved agricultural productivity, and reduction of environmental impacts, require studies of the interactions between different soil components. Fertilizers marketed as "organic" or "natural", such as peats or humic substances (HS) extracted from peats, are enriched with macro and micronutrients that, according to the manufacturers, are released to the plant in accordance with its needs. This work investigates the complexation capacity of HS for macro and micronutrient metal species, considering the competition, for HS complexation sites, between non-essential metals (aluminium and lead), present in the soil, and the nutrients. Humic substances were found to possess strong affinities for Pb(II) and Al(III), forming stable complexes, with concomitant release of complexed nutrients. Although HS are already used commercially as organic fertilizers, further studies of methods of HS enrichment, aimed at avoiding losses, are highly desirable from environmental and economic perspectives.
Assuntos
Ligação Competitiva , Substâncias Húmicas , Metais/química , Solo , Agricultura , AlimentosRESUMO
Investigações sobre os procedimentos de precaução e manipulação dos rejeitos radioativos, gerados na iodoterapia, são muito pouco discutidas na literatura. A aplicação destes procedimentos de precaução, atendendo às normas da legislação vigente, depende diretamente do grau de conhecimento da equipe de enfermagem na manipulação do 131 I, radioisótopo empregado na iodoterapia. Este trabalho apresenta uma avaliação crítica dos procedimentos de precaução e manipulação adotados pela equipe de enfermagem na terapêutica da iodoterapia utilizando um instrumento de análise, validado por um pré-teste e aplicado à equipe de enfermagem da unidade de internação da iodoterapia, em três hospitais (A, B - filantrópicos; C - privado), analisando: conhecimento específico da equipe de enfermagem e atendimento às normatizações. A análise comparativa mostrou significativa diferença dos procedimentos realizados na iodoterapia pela equipe de enfermagem nos hospitais estudados. Os procedimentos de precaução e a adequação da infra-estrutura na realização da terapêutica da iodoterapia dependem fundamentalmente da fiscalização dos órgãos competentes, doconhecimento específico e responsabilidade do profissional responsável pelo serviço de Medicina Nuclear, e do incentivo da direção do estabelecimento prestador de saúde.
Assuntos
Iodo/uso terapêutico , Resíduos RadioativosRESUMO
Aquatic humic substances (AHS) isolated from two characteristic seasons of the Negro river, winter and summer corresponding to floody and dry periods, were structurally characterized by 13C nuclear magnetic ressonance. Subsequently, AHS aqueous solutions were irradiated with a polychromatic lamp (290-475 nm) and monitored by its total organic carbon (TOC) content, ultraviolet-visible (UV-vis) absorbance, fluorescence, and Fourier transformed infrared spectroscopy (FTIR). As a result, a photobleaching up to 80% after irradiation of 48 h was observed. Conformational rearrangements and formation of low molecular complexity structures were formed during the irradiation, as deduced from the pH decrement and the fluorescence shifting to lower wavelengths. Additionally a significant mineralization with the formation of CO2, CO, and inorganic carbon compounds was registered, as assumed by TOC losses of up to 70%. The differences in photodegradation between samples expressed by photobleaching efficiency were enhanced in the summer sample and related to its elevated aromatic content. Aromatic structures are assumed to have high autosensitization capacity effects mediated by the free radical generation from quinone and phenolic moieties.