RESUMO

The trematode Rameshwarotrema uterocrescens (Digenea: Pronocephalidae) parasitizes the glands of the caudal esophagus of Chelonia mydas. In the present study, 741 C. mydas were examined, 85 animals had adult specimens of R. uterocrescens associated with necrotizing ulcerous esophagitis, of these 85, 21 presented invasion of the esophageal mural vessels in the caudal esophagus of juvenile green turtles (Chelonia mydas). Necrotizing granulomatous splenitis, hepatitis, and nephritis were associated with the presence of parasites. The eggs from R. uterocrescens are birefringent under plane-polarized light, which distinguishes them from those of spirorchiid trematodes. This study contributes novel data on R. uterocrescens, methods for detecting this parasite, and demonstrates the fatal potential of parasitism in C. mydas.

RESUMO

Phytoremediation is a technique in which plants are used to treat contaminated media. The objective of this study was to monitor the influence of the parameters pH, phosphate concentration, and nitrate concentration in the process of arsenic absorption by Lemna valdiviana Phil. The response surface methodology was used to analyze the data to subsidize actions that maximize the phytoremediation process. A central composite rotational design (CCRD) was used with 3 variables including 6 axial points and 6 repetitions at the central point, totaling 20 trials. The plants were exposed to a constant concentration of arsenic in the optimization test of 0.5 mg L-1 (NaAsO2) and varied levels of pH, P-PO4, and N-NO3 in a period of 7 d. At the end of the experiment, the mass of arsenic removed from water and arsenic accumulated in the plants, the arsenic species present, the relative growth rate of plants (RGR), the tolerance index (TI), and the bioaccumulation factor (BAF) were calculated. Lemna valdiviana absorbed a greater amount of As when cultivated under pH conditions between 6.3 and 7.0, readily available phosphorus (P-PO4) concentration of 0.0488 mmol L-1, and nitrogen in the form of 7.9 mmol L-1 nitrate. Under these conditions, the plants were able to accumulate 1190 mg kg-1 As (in dry weight) from the aqueous media and reduce 82% of its initial concentration. Therefore, Lemna valdiviana has been shown to be an arsenic bioaccumulating macrophyte with high phytoremediation potential for media contaminated with the metalloid.

Assuntos

RESUMO

Coprecipitation of Fe and Al (hydr)oxides has been considered a low-cost process to remove As from wastewater. Arsenate is the most stable form of As in aerobic environments such as surface water, soils, and sediments and can be removed from water through methods based on this process. Iron/aluminum molar ratios of 100:0, 80:20, and 60:40 were used to treat water contaminated with As at concentrations of 50 and 500 mg L. Aluminum, ferrous, and ferric sulfates were used to coprecipitate Al and Fe (hydr)oxides at high pH. Maghemite, magnetite, lepidocrocite, and goethite were detected in precipitates from Fe(II), whereas hematite and ferrihydrite were identified in Fe(III) treatments. Segregation of Al (hydr)oxides as gibbsite and bayerite as well as the Al isomorphic substitution in Fe (hydr)oxides were detected in the presence of Al. The precipitates were classified as nonhazardous according to the leaching test based on Brazilian Technical Standard NBR 10005. The presence of Al increased the stability of the sludge from Fe(II) treatments but did not affect the stability of precipitates from Fe(III) treatments. High efficiencies for As removal from water were obtained for all treatments, but concentrations of soluble As were, in general, lower for Fe(III) treatments especially, in the absence of Al. Treatments were efficient in reaching the threshold to effluent discharge (0.5 mg L), but only treatments with initially 50 mg L of As reached the threshold for drinking water (10 µg L).

Assuntos

RESUMO

This study aimed to evaluate the pH, phosphate, and nitrate in the process of arsenic absorption by Eichhornia crassipes (water hyacinth), using the surface response methodology, in order to optimize the process. The plants were exposed to a concentration of arsenic of 0.5 mg L-1 (NaAsO2) over a period of 10 days. The results indicated optimal levels for the absorption of arsenic by E. crassipes at pH equal to 7.5, absence of phosphate, and minimum nitrate level of 0.0887 mmol L-1. For the tested concentration, E. crassipes was able to accumulate 498.4 mg kg-1 of As (dry base) in its plant tissue and to reduce 83% of the initial concentration present in the aqueous medium where it was cultivated. The concentration of phosphorus in solution linearly increased the phosphorus content in the plants and negatively influenced the absorption of arsenic. The concentration of 0.5 mg L-1 of As did not significantly affect the relative growth rate (RGR) and the tolerance index (TI). 94% of As (III) initially solubilized in water was converted by the end of the experiment period into As (V). The water hyacinth was important in the phytoremediation of arsenic when cultivated under optimal conditions for its removal.

Assuntos

RESUMO

Use of lime to mitigate acid mine drainage is, in general, accompanied by precipitation of iron (Fe) and aluminium (Al) (hydr)oxides which may increase the removal of trace elements from water. This work aimed to evaluate the precipitation of Fe/Al (hydr)oxides to remove rare earth elements (REE) from contaminated water and the stability of precipitates. Two sets of 60-day syntheses were carried out using different Fe/Al/REE molar ratios, for europium (Eu) and holmium (Ho). The pH was periodically adjusted to 9.0, and the stability of the resulting precipitates was evaluated by water-soluble and BCR extractable phases, namely (1) acid soluble, extracted by 0.11 mol L-1 acetic acid; (2) reducible, extracted with 0.5 mol L-1 hydroxylamine hydrochloride; and (3) oxidisable, extracted with 8.8 mol L-1 hydrogen peroxide efficiencies of the water treatments for both Eu and Ho that were higher than 99.9% irrespective to the Fe/Al/REE molar ratios. Water-soluble phases of Eu and Ho were lower than 0.01% of the total contents in the precipitates. Recoveries from precipitates by Bureau Communautaire de Référence (BCR) sequential extractions increased with increasing concentrations of Eu and Ho. Acetic acid extracted higher amounts of REE, but Eu recovery was superior to Ho. Lepidocrocite was formed as Eu concentration increased which decreased its stability in the precipitates.

Assuntos

RESUMO

Several methods to remove arsenic from water have been considered, including co-precipitation with Fe and Al (hydr)oxides. Such compounds are considered very effective to remove As from contaminated water due to strong bindings between them. Three Fe:Al molar ratios (100:0, 80:20, and 60:40) were used to synthesize aluminum, ferrous, and ferric (hydr)oxides by precipitation in water highly contaminated with arsenite (50 and 500 mg L-1). The method was very efficient for all treatments (> 93%) at the beginning of the incubation period, excepted the one with 60:40 Fe(II):Al molar ratio at the higher As concentration (500 mg L-1) in which gibbsite was identified in precipitated phases. In spite of the high efficiency, however, the threshold for drinking water was not attained, mainly to the higher As concentration, even 84 days after precipitation. At this high concentration of arsenite, even the required threshold for effluent discharge was not attained in some treatments. The sludge resulting from treatments with higher As concentration were considered hazardous according to results from leaching test and corroborated by BCR extractions. Arsenic associated with Al and adsorbed phases were also assessed by extractions with NH4F and KH2PO4, respectively. In general, the presence of Al increased the efficiency as well as the stability of the sludge resulting from Fe (II) treatments, but did not affect Fe (III) treatments, which were more efficient for As removal.

Assuntos

RESUMO

Este artigo procura realizar uma análise da retomada da família nas políticas sociais, destacando as contradições decorrentes da instituição do Estado Democrático de Direito num contexto de avanço da ideologia neoliberal e de transição do fordismo para o regime de acumulação flexível. A partir de uma perspectiva marxista, destaca que a ampliação dos diplomas legais voltados à proteção dos sujeitos acompanha a incorporação progressiva das demandas por direitos humanos, ao mesmo tempo em que as pressões por cortes orçamentários se acentuam, demarcando as limitações da capacidade de o Estado garantir a cidadania, assumindo a sua responsabilidade com a reprodução social. O efeito desse descompasso sobre as famílias das classes trabalhadoras lança ao horizonte qualquer intenção de emancipação pela via do direito. Pelo contrário, nos dias atuais, a primazia consiste em empregá-lo como dispositivo de controle, amplamente coercitivo, em vez de servir como fonte para a promoção social.

This essay seeks to analyze the resumption of the family in social policies, highlighting the contradictions arising from the establishment of a democratic State of law in the context of advancement of neoliberal ideology and the transition from Fordism to the regime of flexible accumulation. From a Marxist perspective, emphasizes that the expansion of legislation aimed at the protection of the subject follows the progressive incorporation of demands for human rights, while the pressures for budget cuts are accentuated, demarcating the limitations of the capacity of the State to ensure the citizenship, assuming its responsibility to the social reproduction. The effect of this mismatch on working-class families launches to the horizon any intention of emancipation through the right. On the contrary, nowaday, the priority is to use it as a control device, largely coercive, rather than serve as a source for social promotion.

Assuntos

RESUMO

Investiga como os dirigentes de entidades hospitalares lucrativas, que prestam serviços ao Sistema Unico de Saúde, percebem as alteraçöes que estäo havendo no setor saúde. Se serve de um referencial histórico que narra a construçäo de um modelo político-administrativo, ao longo dos anos de regime militar, e sua evoluçäo propiciada pelo processo de redemocratizaçäo da sociedade brasileira nas décadas de 1970-80. Respaldando-se na legislaçäo em vigor, busca dados que permitam definir quais aspectos, implicados na referida trajetória democratizante, sensibilizam os dirigentes de hospitais lucrativos e motivam suas açöes na conduçäo dos serviços médicos-hospitalares em questäo.

Assuntos