Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 129
Filtrar
Mais filtros

Tipo de documento
Intervalo de ano de publicação
1.
Development ; 149(3)2022 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-34931661

RESUMO

Endothelial cell migration and proliferation are essential for the establishment of a hierarchical organization of blood vessels and optimal distribution of blood. However, how these cellular processes are quantitatively coordinated to drive vascular network morphogenesis remains unknown. Here, using the zebrafish vasculature as a model system, we demonstrate that the balanced distribution of endothelial cells, as well as the resulting regularity of vessel calibre, is a result of cell migration from veins towards arteries and cell proliferation in veins. We identify the Wiskott-Aldrich Syndrome protein (WASp) as an important molecular regulator of this process and show that loss of coordinated migration from veins to arteries upon wasb depletion results in aberrant vessel morphology and the formation of persistent arteriovenous shunts. We demonstrate that WASp achieves its function through the coordination of junctional actin assembly and PECAM1 recruitment and provide evidence that this is conserved in humans. Overall, we demonstrate that functional vascular patterning in the zebrafish trunk is established through differential cell migration regulated by junctional actin, and that interruption of differential migration may represent a pathomechanism in vascular malformations.


Assuntos
Vasos Sanguíneos/crescimento & desenvolvimento , Morfogênese/genética , Molécula-1 de Adesão Celular Endotelial a Plaquetas/genética , Proteína da Síndrome de Wiskott-Aldrich/genética , Actinas/genética , Animais , Artérias/crescimento & desenvolvimento , Artérias/metabolismo , Movimento Celular/genética , Proliferação de Células/genética , Células Endoteliais/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/genética , Humanos , Junções Intercelulares/genética , Veias/crescimento & desenvolvimento , Veias/metabolismo , Peixe-Zebra/genética , Peixe-Zebra/crescimento & desenvolvimento
2.
Clin J Sport Med ; 33(2): 183-186, 2023 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-36730666

RESUMO

OBJECTIVE: To describe and present the clinical results of a new surgical treatment for sports hernia. DESIGN: Retrospective cohort study. SETTING: Tertiary hospital. PATIENTS: Athletes who underwent sports hernia repair using the proposed technique between July 2006 and June 2020. INTERVENTION: The surgery consists of a combination of a mini-open incision and preperitoneal placement of a three-dimensional bilayer permanent mesh (PHS). MAIN OUTCOME MEASURES: The main clinical outcomes of the procedure were reviewed, including incidence of complications, long-term results, and recurrence rate. RESULTS: Ninety-two sports hernia repairs were performed on 87 patients (79 male and 8 female patients, median age 30.2 ± 7.8 years). No intraoperative complications were observed. The mean follow-up was 15 months. Seventy-seven patients (88.5%) successfully resumed preinjury physical activities within 8 weeks; 80 patients (91.9%) within 12 weeks; and 83 (95.4%) within 6 months (median time of 10 weeks). Only one patient reported recurrence of symptoms. CONCLUSION: Mini-open incision PHS repair seems to be a safe and effective method for treatment of sports hernia, resulting in early return to physical activities, with few complications, and low recurrence rate.


Assuntos
Hérnia Inguinal , Herniorrafia , Humanos , Masculino , Feminino , Adulto Jovem , Adulto , Resultado do Tratamento , Herniorrafia/métodos , Polipropilenos , Estudos Retrospectivos , Hérnia Inguinal/cirurgia , Hérnia Inguinal/diagnóstico , Recidiva
3.
Environ Geochem Health ; 45(5): 2415-2434, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-35986856

RESUMO

Spatial distribution linked to geostatistical techniques contributes to sum up information into an easier-to-comprehend knowledge. This study compares copper spatial distribution in surface sediments and subsequent categorization according to its toxicological potential in two reservoirs, Rio Grande (RG) and Itupararanga (ITU) (São Paulo-Brazil), where copper sulfate is applied and not applied, respectively. Sediments from 47 sites in RG and 52 sites in ITU were collected, and then, copper concentrations were interpolated using geostatistical techniques (kriging). The resulting sediment distributions were classified in categories based on sediment quality guides: threshold effect level and probable effect level; regional reference values (RRVs) and enrichment factor (EF). Copper presented a heterogenic distribution and higher concentrations in RG (2283.00 ± 1308.75 mg/kg) especially on the upstream downstream, associated with algicide application as well as the sediment grain size, contrary to ITU (21.81 ± 8.28 mg/kg) where a no-clear pattern of distribution was observed. Sediments in RG are predominantly categorized as "Very Bad", whereas sediments in ITU are mainly categorized as "Good", showing values higher than RRV. The classification is supported by the EF categorization, which in RG is primarily categorized as "Very High" contrasting to ITU classified as "Absent/Very Low". Copper total stock in superficial sediment estimated for RG is 4515.35 Ton of Cu and for ITU is 27.45 Ton of Cu.


Assuntos
Sulfato de Cobre , Poluentes Químicos da Água , Sulfato de Cobre/toxicidade , Cobre/toxicidade , Cobre/análise , Ecotoxicologia , Sedimentos Geológicos , Brasil , Monitoramento Ambiental/métodos , Poluentes Químicos da Água/toxicidade , Poluentes Químicos da Água/análise
4.
Development ; 146(16)2019 08 27.
Artigo em Inglês | MEDLINE | ID: mdl-31375478

RESUMO

How developing vascular networks acquire the right balance of arteries, veins and lymphatic vessels to efficiently supply and drain tissues is poorly understood. In zebrafish embryos, the robust and regular 50:50 global balance of intersegmental veins and arteries that form along the trunk prompts the intriguing question of how does the organism keep 'count'? Previous studies have suggested that the ultimate fate of an intersegmental vessel (ISV) is determined by the identity of the approaching secondary sprout emerging from the posterior cardinal vein. Here, we show that the formation of a balanced trunk vasculature involves an early heterogeneity in endothelial cell behaviour and Notch signalling activity in the seemingly identical primary ISVs that is independent of secondary sprouting and flow. We show that Notch signalling mediates the local patterning of ISVs, and an adaptive flow-mediated mechanism subsequently fine-tunes the global balance of arteries and veins along the trunk. We propose that this dual mechanism provides the adaptability required to establish a balanced network of arteries, veins and lymphatic vessels.


Assuntos
Padronização Corporal , Receptores Notch/metabolismo , Peixe-Zebra/embriologia , Animais , Artérias/embriologia , Polaridade Celular , Células Endoteliais/fisiologia , Heterogeneidade Genética , Vasos Linfáticos/embriologia , Fluxo Sanguíneo Regional , Transdução de Sinais , Veias/embriologia , Peixe-Zebra/sangue
5.
J Environ Manage ; 317: 115402, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-35751244

RESUMO

The process of extracting information from data generated in environmental monitoring programs is often carried out using statistical tools, with Statistical Process Control (SPC) showing great potential for application in environmental monitoring. In November 2015, millions of cubic metres of tailings were dumped into the basin of the River Doce with the collapse of the Fundão dam. A study of the impact of this incident requires new approaches in data monitoring and processing, so it was sought to evaluate, using SPC tools, changes in water quality in the basin of the River Doce following the collapse of the dam. Using process charts and the process capability index (PCI), water quality parameters in the Doce and Carmo rivers were evaluated between 2009 and 2020. There, turbidity has improved since 2018, and Mn since 2016. Control charts showed that by December 2020 dissolved Fe was still not within normal pre-event fluctuation patterns. The PCI value showed that the situation worsened after the event for each of the parameters, with the lowest values for Mn and E. coli. By using a reference period, SPC makes it possible to infer the permanence of the impact of extreme pollution on the waterbody, which can be used in the routine monitoring of water quality in such events.


Assuntos
Desastres , Poluentes Químicos da Água , Brasil , Monitoramento Ambiental , Escherichia coli , Rios , Poluentes Químicos da Água/análise , Qualidade da Água
6.
Water Sci Technol ; 83(12): 3007-3019, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34185695

RESUMO

The biogas produced in UASB-based sewage treatment plants (STPs) is rarely used for energy purposes and its potential is often unknown. This study aimed to propose a simple and reliable method based on energy balance to determine the technical feasibility of biogas use and the energy self-sufficiency of UASB reactors. To this end, we considered (i) electric power production (E) and (ii) electric power consumption (Econ) ascribed to sewage pumping stations (SPSs) at different pressure heads (0 to 4 m, 4.1 to 8 m, 8.1 to 12 m, and 12.1 to 16 m). The technical feasibility of biogas use was assessed by evaluating if the flow of biogas produced in the STPs would be sufficient for the functioning of a commercial motor-generator. The linear model fit to estimate the biogas energy potential (y-axis) in STPs and the sewage flow (x-axis) is represented by y = 122.65x (R2 = 0.64). In total, 1,054 STPs in Brazil use UASB reactors as treatment units, of which nearly 31% are located in the southeast. However, only 11.2% of these STPs, which serve populations of over 29,981, presented technical feasibility to recover biogas. The mathematical equations proposed in this study to estimate the net electric power production in UASB-based STPs are relevant tools for sanitation companies and can enable studies to be performed for the implementation of energy self-sufficiency projects in Brazil.


Assuntos
Biocombustíveis , Esgotos , Anaerobiose , Reatores Biológicos , Brasil , Estudos de Viabilidade , Eliminação de Resíduos Líquidos
7.
Gen Dent ; 69(5): 14-19, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34424206

RESUMO

The use of autogenous materials to promote tissue regeneration has guided the direction of modern dentistry, and platelet-rich fibrin (PRF) is a promising biomaterial for tissue engineering. This in vitro immunohistochemical study aimed to analyze the presence of factors of endothelial growth and cell differentiation in PRF membranes by using the CD31 (endothelial cells) and CD163 (monocytes) markers. Five men and 5 women, aged between 25 and 60 years and without systemic health problems, were enrolled in the study. Blood samples were collected, submitted to a centrifugation protocol, and fixed in 4% formaldehyde, and then immunohistochemical analysis was performed. The histologic analysis of the slides showed that the fibrin clot was formed by a dense fiber network and cells trapped in its structure. One sample was excluded from the markers testing due to poor quality. All 9 of the valid samples were positive for the CD31 and CD163 markers, with reactivity ranging from 5% to 30% and 10% to 40% of cells, respectively. The immunohistochemical analysis showed the presence of CD31 and CD163 in the PRF membranes, indicating the potential for vascular neoformation and the significant presence of monocytes, which play an important role in tissue remodeling via their differentiation into macrophages.


Assuntos
Fibrina Rica em Plaquetas , Adulto , Plaquetas , Centrifugação , Células Endoteliais , Feminino , Fibrina , Humanos , Masculino , Pessoa de Meia-Idade
8.
J Contemp Dent Pract ; 22(7): 778-783, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34615784

RESUMO

AIM AND OBJECTIVE: This study aimed to evaluate the epidemiological profile, oral health self-perception index, and level of satisfaction of users of complete implant-supported overdentures that had been used for at least 1 year and were made at the School of Dentistry of the University of Passo Fundo, Rio Grande do Sul, Brazil (FO/UPF), between 2014 and 2019. MATERIALS AND METHODS: The sample consisted of 30 patients with overdentures, who were selected from the dental records filed at the institution. Data on general health and the dental implants involved (brand, type of prosthetic connection, number of implants, and additional overdenture retention system) were collected from the medical records. The 30 patients were invited to answer the Oral Health Impact Profile-14 (OHIP-14) and visual analog scale (VAS) questionnaires, and due to the coronavirus disease 2019 pandemic, it was possible to contact 15 patients. RESULTS: Most of the prostheses studied were mandibular overdentures, and 66.66% of the cases were retained by the O-ring system. As for the oral health self-perception of the individuals, it was concluded that male patients had a lower mean overall score (p = 0.047) and functional domain (p = 0.042) in the OHIP-14. The number of implants and the installation arch interfered with functional domain and psychological capacity (p <0.05). The VAS showed that women have greater esthetic satisfaction with prostheses (p = 0.048) and that the bar-clip retention system is more satisfactory than the O-ring (p = 0.017). CONCLUSION: Despite the limitations of overdentures, it was noted that, when properly indicated, they are a viable option for oral rehabilitation on implants. CLINICAL SIGNIFICANCE: Oral rehabilitation well-indicated with overdentures, especially those retained by the bar-clip system, results in an improvement in the patients' quality of life.


Assuntos
COVID-19 , Revestimento de Dentadura , Brasil/epidemiologia , Estética Dentária , Humanos , Masculino , Qualidade de Vida , SARS-CoV-2 , Instituições Acadêmicas
9.
Anal Bioanal Chem ; 412(3): 703-714, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31828374

RESUMO

Diffusive gradients in thin films technique (DGT) allows in situ determination of labile metal in water, soils, and sediments. This paper aims to evaluate the performance of a new proposal of DGT to measure Cu2+ and Cd2+ in aqueous solution using chitosan films as binding agent. These films were prepared and characterized (Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscope, and elemental analysis). The maximum adsorption rates onto chitosan films at initial concentrations of 0.5 and 1.0 mg L-1 for Cu2+ and Cd2+ were 97%, 98% and 60%, 62%, respectively. Effects of main DGT parameters were evaluated and the results obtained suggest that the pH between 4.0 and 6.0 and ionic strength from 0.0008 to 0.1 mol L-1 presented the best ranges for the application of DGT-Chitosan. The results suggest that chitosan films prepared in this work can be an effective binding agent for DGT technique in aqueous solution. Graphical abstract.

10.
An Acad Bras Cienc ; 92(2): e20180962, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32321032

RESUMO

Benthic macroinvertebrates are organisms that are recognized as water quality bio-indicators. A wide variety of indices and metrics have been shown to respond to a variety of anthropogenic impacts, usually under a general condition of environmental impairment. The absence of a clear distinction in the relations between specific pollutants and biotic variables is very common and can lead to biased interpretation of biomonitoring. The aims of this research were to test taxonomic and non-taxonomic responses to specific environmental conditions instead to general conditions. For this purpose, we estimated the theoretical toxicity by comparing toxicity values published by EPA with metal concentrations in water and sediments. Then we tested the responses of biological variables to toxicity and other environmental conditions using the linear mixed effects models approach. We generated 32 models considering 24 different biological metrics and indices that were grouped in five levels. Taxonomic and abundance metrics were best predictor than functional or tolerance-based indexes. The strongest model was that which considered subfamily taxonomic resolution responding to Al_w and Cr_s.


Assuntos
Invertebrados/química , Metais/toxicidade , Poluentes Químicos da Água/análise , Animais , Brasil , Clorofila A/análise , Ecossistema , Monitoramento Ambiental/métodos , Sedimentos Geológicos/análise , Invertebrados/classificação , Modelos Lineares , Fósforo/análise , Análise de Componente Principal , Rios/química
11.
Water Sci Technol ; 82(8): 1579-1585, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33107852

RESUMO

In the present work the use of a promising novel coagulant aid, Guazuma ulmifolia, was optimized to treat synthetic water using central composite being highly efficient at rotatable design (CCRD). The factors evaluated for the coagulation-flocculation process were coagulants dosages and pH. A model to describe the coagulation-flocculation process was successfully obtained. The model was validated using 5 mg L-1 aluminum sulfate, 2.5 mg L-1 G. ulmifolia and pH 9, achieving excellent agreement with observed values.


Assuntos
Purificação da Água , Floculação
12.
PLoS Biol ; 13(4): e1002125, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25884288

RESUMO

Patterning of functional blood vessel networks is achieved by pruning of superfluous connections. The cellular and molecular principles of vessel regression are poorly understood. Here we show that regression is mediated by dynamic and polarized migration of endothelial cells, representing anastomosis in reverse. Establishing and analyzing the first axial polarity map of all endothelial cells in a remodeling vascular network, we propose that balanced movement of cells maintains the primitive plexus under low shear conditions in a metastable dynamic state. We predict that flow-induced polarized migration of endothelial cells breaks symmetry and leads to stabilization of high flow/shear segments and regression of adjacent low flow/shear segments.


Assuntos
Vasos Sanguíneos/citologia , Endotélio Vascular/citologia , Animais , Polaridade Celular , Modelos Biológicos
14.
Ecotoxicol Environ Saf ; 162: 616-624, 2018 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-30031910

RESUMO

Water contamination of As is a big issue in many areas around the globe. Therefore, cheap and efficient techniques are essential facing traditional treatment methods. Then, biochars (BC) emerged recently as material that can be used for As removal. However, research about efficiency of BC produced from local feedstock is still needed. The purpose of this study is to assess the efficiency of BC produced from sugarcane bagasse (SB) together with corncob husk (CH) with and without Fe(III) (BCFe) modification to be used for removal of As(III) from waters. The BC and BCFe produced at different pyrolysis temperatures were characterised using FTIR and SEM/EDS. Adsorption capacities of BC and BCFe were evaluated via batch adsorption, desorption and column tests and their performance was compared with adsorption using activated carbon. The results showed that Fe modification improve substantially the As(III) adsorption in a way that both BCFe-SB and BCFe-CH removed from 85% to 99.9% from 1000 µg/L As(III) solutions. Both materials fitted well in Langmuir model and the maximum adsorption capacity was 20 mg/g for BCFe-SB and 50 mg/g for BCFe-CH. The adsorption kinetics of BCFe was fast (≤ 30 min) and it had a better performance than activated carbon. The column tests showed that the process is efficient even at high As(III) concentrations. The fast removal process and good removal results make the BCFe-SB and BCFe-CH attractive for in situ and commercial (filters) use, since time and efficiency are required in new technologies.


Assuntos
Arsenitos/isolamento & purificação , Celulose/química , Carvão Vegetal/química , Compostos Férricos/química , Poluentes Químicos da Água/isolamento & purificação , Concentração de Íons de Hidrogênio , Modelos Teóricos , Saccharum/química , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Purificação da Água , Zea mays/química
15.
Ecotoxicology ; 27(3): 286-299, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29372366

RESUMO

The Cantareira Complex is one of the most important water supplies of the metropolitan region of São Paulo, Brazil. Previously, it was demonstrated that the sediments in this complex were polluted with metals and that Paiva Castro Reservoir-the last reservoir in the sequence, which receives water from the five previous reservoirs-was the reservoir with the greatest concentration of pollutants. Based on field data, it was noticed that copper concentrations in sediments were related to morphological alterations in chironomids. The present study provides novel monitoring methods and results for the complex by isolating the environmental and biological sources of variation. An adaptation of the in situ assay proposed by Soares et al. (Arch Environ Contam Toxicol 49:163-172, 2005), which uses a native tropical Chironomus species and low-cost materials, is also provided. The aim of this study was to isolate the effects of sediments from Paiva Castro on controlled populations of C. sancticaroli larvae using an in situ assay. A seven-day experiment was performed in triplicate. Third instar larvae were inoculated in chambers containing sediments from two distinct regions of Paiva Castro reservoir and a control site with sand. Five biological responses were considered: mouthpart alterations, larval length, width of cephalic capsule, mortality and total damage. The results suggest the effects of sediment toxicity on larvae include a reduction in length and a higher occurrence of total damage.


Assuntos
Chironomidae/efeitos dos fármacos , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Metais Pesados/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Brasil , Chironomidae/crescimento & desenvolvimento , Monitoramento Ambiental/instrumentação , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Rios/química
16.
Environ Monit Assess ; 190(4): 199, 2018 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-29520500

RESUMO

Depending on the environmental conditions, surface sediments can retain all the contaminants present and provide a record of the anthropic activities affecting the aquatic environment. In order to analyze the impacts on reservoirs, surface sediments were collected in three characteristic regions (riverine, transitional, and limnetic zones) of seven reservoirs in São Paulo State, Brazil. Analyses were made of grain size, organic matter (OM), total phosphorus (TP), and total nitrogen (TN). Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) was used to determine pseudo-total and bioavailable metals (Cu, Cd, Cr, Ni, Pb, Zn, Mn, Fe, and Al). A Horiba probe was used to measure dissolved oxygen (DO), pH, redox potential (ORP), and temperature (Temp) in the bottom water. The data were analyzed using multivariate statistics. Enrichment factors (EF), pollution load index values (PLI), and background values (BG) were also determined in order to evaluate the potential toxicity. Intra-reservoir and inter-reservoir spatial heterogeneity (p < 0.05) were observed using two-way analysis of similarities. Principal component analysis indicated greater influence of metals in the Barra Bonita, Salto Grande, and Rio Grande reservoirs, corroborating the PLI, EF, and BG data. Bioavailable Cu was found in the Rio Grande reservoir, possibly associated with copper sulfate used to control algal blooms, while bioavailable Ni in the Barra Bonita reservoir was attributed to the presence of industrial wastes and natural geology. The bottom water conditions indicated that the metals remained in insoluble forms.


Assuntos
Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Resíduos Industriais/análise , Metais Pesados/análise , Poluentes Químicos da Água/análise , Disponibilidade Biológica , Brasil , Nitrogênio/análise , Oxirredução , Oxigênio/análise , Fósforo/análise , Análise de Componente Principal , Espectrofotometria Atômica
17.
Bull Environ Contam Toxicol ; 100(5): 627-633, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29541818

RESUMO

Aiming to determine the relationship between source and complexing capacity, humic substances obtained from three sites (Sorocaba and Itapanhau Brasilian rivers, and Xochimilco Lake in Mexico) were studied. Copper, manganese, zinc and arsenic complexing capacity were determined for the three substances under various pH conditions. Results showed similar complexing capacity for the three elements depending on the chemistry of each one and on the physico-chemical conditions. Speciation diagrams showed that these conditions affect both, the humic substances, and the transition metals and arsenic.


Assuntos
Monitoramento Ambiental , Substâncias Húmicas/análise , Poluentes Químicos da Água/análise , Arsênio/análise , Complexos de Coordenação/análise , Cobre/análise , Íons/análise , México , Rios/química , Poluentes Químicos da Água/química , Zinco/análise
18.
Bull Environ Contam Toxicol ; 100(6): 778-785, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29651544

RESUMO

The sediment compartment stands out because it functions as both a temporary sink of pollutants and a potential source of these elements that may become available to the water column.This study aimed to correlate the concentrations of total metals in the crude sediment and in the interstitial water with the ecotoxicity in the water column using an a modified sediment ecotoxicity test with Ceriodaphnia dubia. The results indicate that the sediment may contribute to the toxicity in the water column and that such toxicity is possibly not related to the metals present. Based on the chemical analysis of the metals, the Canadian Sediment Quality Guidelines (SQGs) would frame the sediment as non-toxic to benthic organisms, but the SQGs have no reference standards for possible effects on nektonic organisms. Due to the complexity of this compartment, it is fundamental to evaluate the interactions of the different pollutants in the system and possible effects on the nektonic organisms.


Assuntos
Sedimentos Geológicos/química , Metais/análise , Poluentes Químicos da Água/análise , Animais , Organismos Aquáticos/metabolismo , Canadá , Cladocera/metabolismo , Água/análise
19.
Ecotoxicol Environ Saf ; 139: 1-8, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28092735

RESUMO

The release of contaminants in aquatic ecosystems can be influenced by humic acids. In this study, toxicity tests using environmentally relevant concentrations of arsenic and cobalt were conducted both in the presence and absence of aquatic humic substances (AHS) and the fractions of different molecular sizes in the range of (<5, 5-10;10-30; 30-100 and >100kDa) using the microcrustacean Ceriodaphnia dubia. AHS together with arsenic reduced the toxicity, and the toxicity decreased in fractions of larger molecular size AHS. Despite the presence of cobalt, the reduction in toxicity was not observed and that depended on the molecular size of AHS. There was a trend of enhanced toxicity for Co in fractions of larger molecular sizes, opposed to that found for arsenic. Thus, the humic substances alter toxicity of trace elements, and this effect varies depending on the size of the humic substances.


Assuntos
Arsênio/toxicidade , Cladocera/efeitos dos fármacos , Cobalto/toxicidade , Ecossistema , Substâncias Húmicas , Poluentes Químicos da Água/toxicidade , Animais , Exposição Ambiental
20.
Environ Monit Assess ; 188(5): 310, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27117444

RESUMO

Sediments may be a repository of contaminants in freshwater ecosystems. One way to assess the quality of this compartment, in terms of potentially bioavailable metals, is by the analysis of acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM). In order to investigate the bioavailability, toxicity, and compartmentalization of different metals (Cd, Cr, Cu, Ni, Pb, Zn), sampling of surface sediments was performed at nine stations along the Paiva Castro reservoir (São Paulo, Brazil). The metals were analyzed using atomic absorption spectroscopy. Sediment organic matter (OM), organic carbon (OC), and grain size were also measured. The parameters pH, EH, temperature, and dissolved oxygen were determined at the sediment-water interface. Chronic and acute toxicological tests were performed with sediments from the area where water was extracted for the public water supply. Low levels of OM, associated with loss of stratification in the water column, explained the relatively low AVS values. The molar ratio ∑[SEM]-[AVS]/fOC was less than 130 mmol/kg(-1) for all the sampling stations, indicating that the metals were not bioavailable. With the exception of Cd, metal levels were in accordance with background concentrations and the threshold effect level (TEL) established by the Canadian Council of Ministers of the Environment. The ecotoxicological tests confirmed the absence of toxic effects to biota. Application of principal component analysis indicated the presence of four compartments along the reservoir: (1) a riverine zone, potentially threatened by contamination with Cd; (2) an intermediate zone; (3) a limnic area; and (4) the area where water was taken for the public water supply.


Assuntos
Monitoramento Ambiental , Sedimentos Geológicos/química , Metais/análise , Poluentes Químicos da Água/análise , Brasil , Canadá , Água Doce/química , Metais/toxicidade , Sulfetos/análise , Poluentes Químicos da Água/toxicidade , Abastecimento de Água/estatística & dados numéricos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA