Constructed wetlands as an alternative for arsenic removal from reverse osmosis effluent.

In Argentina, drinking water for c.a. 10% of the population has arsenic (As) concentrations higher than those recommended by WHO (10 µg L-1). Reverse osmosis (RO) appears as an immediate and effective solution for As remediation. However, this process has a residual flow known as "rejection" or "concentrate" where dissolved species are more concentrated than in the feed flow. In this study, phytoremediation with subsurface horizontal-flow constructed wetlands (CW) was proposed to reduce As concentration in the RO residues. Experiments were carried out during 419 days at room temperature and using a continuous regime (flow of 36 L d-1, As concentration around 85 µg L-1) of RO rejection from a water treatment plant located in Buenos Aires province, Argentina. The study was performed using prototypes planted with Cyperus haspan (PA), Juncus effusus (PB) and a mix of inert gravel and laterite (substrate) that was used as a control (PC). Results showed that after a stabilization time, As removal (%) was between 30% and 80% in the CW planted with J. effusus and between 10 and 40% with C. haspan. As concentration along CW showed similarities between the prototypes PC and PA. The cumulative mass of As was 62%, 34% and 27% for PA, PB and PC, respectively. The contribution of C. haspan and J. effusus during the experimental time was between 12 and 67% and 22 to 87%, respectively. The bioaccumulation and translocation factors indicated that for J. effusus the accumulation is more important than the translocation process (1.6 and 0.2, respectively), while for C. haspan both factors were similar (1.1 and 1.0, respectively). Results suggested that this technology has the potential for an efficient and environmentally sustainable alternative to RO rejection treatment and disposal regarding As concentration.

Non-destructive methodologies applied to track the occurrence of natural micropollutants in watering: Glycine max as a biomonitor.

Groundwater is habitually used for watering purposes in rural areas where the rainfall is not enough to adequately cover the crop requirements. However, groundwater sources could be naturally contaminated with trace micropollutants like As and associated elements (B, V and F) adversely affecting the plant health. In this work, non-destructive methodologies based on reflectance and chlorophyll emission processes were applied to assess the presence of micropollutants in watering by using a widespread crop (soybean plant). One of the most substantial results is that the co-occurrence of As, V, B and F in the watering solution clearly produced a synergistic effect in the plants. In fact, both reflectance and fluorescence techniques were proved in this work to be effective in detecting non-destructively stress by multielement treatment. Particularly, for reflectance measurements the most sensitive parameters were the derivative peak area between 480 and 560 nm and the chlorophyll content. Furthermore, it was demonstrated that it is possible to successfully use a portable hyperspectral spectroradiometer instead of a conventional spectrophotometer as the determinations performed with both instruments were positively correlated. Concerning fluorescence, variable emission of chlorophyll-a was more sensitive to stress than steady-state emission. The parameter Fv/F0 was a valuable indicator of stress but the quantum yields of PSII and NPQ stood out as the most sensitive indices with variations of around 60 and 100% respectively.

Trace metals and oxidative status in soft tissues of caged mussels (Aulacomya atra) on the North Patagonian coastline.

This study investigated metal accumulation and oxidative effects in mantle, gill and digestive gland of the ribbed mussel Aulacomya atra from the Argentinean North Patagonian coastline. Mussels were transplanted over an 18-month period from a site with low anthropogenic impact to a harbor site with higher seawater concentration of aluminum, chromium, copper, manganese, nickel and zinc. Total trace metal concentration in seawater did not change throughout the 18-month transplant in either site. A. atra bioaccumulated metals in digestive gland, gills and mantle at different levels. Digestive gland had the highest concentration of metals, especially towards the end of the transplant experiment in the harbor area. Mussels transplanted to the harbor site experienced an upregulation in their antioxidant system, which likely explains the lack of oxidative damage to lipids despite higher metal accumulation. These results demonstrate that A. atra selectively accumulates metals from the water column and their prooxidant effects depend on the tissue antioxidant defenses and the exposure time.

Cr(VI) and Cr(III) removal from aqueous solution by raw and modified lignocellulosic materials: a review.

In aqueous systems, chromium usually exists in both trivalent and hexavalent oxidation states, being Cr(VI) of particular importance and concern due to its great toxicity. Industrial sources of Cr(VI) are leather tanning, mining of chrome ore, production of steel and alloys, etc. The most common conventional method for Cr(VI) removal is reduction to Cr(III) at pH 2.0 and precipitation of Cr (OH)(3) with lime at pH 9-10. The disadvantage of precipitation is the disposal of the solid waste. Adsorption of Cr by different low cost materials seems to be a suitable choice for wastewater treatment. Many by-products of agriculture have proved to be suitable low cost adsorbents for Cr(VI) and Cr(III) removal from water. Lignocellulosic residues, which include both wood residues and agricultural residues, have adsorption capacity comparable to other natural sorbents, but they have the advantage of very low or no cost, great availability and simple operational process. This study is a review of the recent literature on the use of natural and modified lignocellulosic residues for Cr adsorption. The Cr maximum adsorption capacity and the adsorption mechanism under different experimental conditions are reported when possibly.

Hg(II) removal from water by chitosan and chitosan derivatives: a review.

Mercury (Hg) is one of the most toxic heavy metals commonly found in the global environment. Its toxicity is related to the capacity of its compounds to bioconcentrate in organisms and to biomagnify through food chain. A wide range of adsorbents has been used for removing Hg(II) from contaminated water. Chitosan is obtained by alkaline deacetylation of chitin. The adsorption capacity of chitosan depends on the origin of the polysaccharide, and on the experimental conditions in the preparation, that determine the degree of deacetylation. A great number of chitosan derivatives have been obtained by crosslinking with glutaraldehyde or epichlorohydrin among others or by grafting new functional groups on the chitosan backbone with the aim of adsorbing Hg(II). The new functional groups are incorporated to change the pH range for Hg(II) sorption and/or to change the sorption sites in order to increase sorption selectivity. The chemical modification affords a wide range of derivatives with modified properties for specific applications. Hg(II) adsorption on chitosan or chitosan derivatives is now assumed to occur through several single or mixed interactions: chelation or coordination on amino groups in a pendant fashion or in combination with vicinal hydroxyl groups, electrostatic attraction in acidic media or ion exchange with protonated amino groups. This review reports the recent developments in the Hg(II) removal in waste water treatment, using chitosan and its derivatives in order to provide useful information about the different technologies. When possibly the adsorption capacity of chitosan and chitosan derivatives under different experimental conditions is reported to help to compare the efficacy of the Hg(II) removal process. A comparison with the adsorption capacity of other low-cost adsorbents is also tabled.

Coeficientes de partición de hidrocarburos aromáticos policíclicos con sustancias húmicas: un método simple para su determinación / Binding coefficients of polycyclic aromatic hydrocarbons to humic substances: a simple method for their determination

Las sustancias húmicas son componentes importantes de las aguas naturales, son polímeros ácidos, predominantemente aromáticos, que no resultan nocivos a los seres vivos. Sin embargo, su rol en el medio ambiente es importante porque afectan a la biodisponibilidad y toxicidad de muchos compuestos en el ambiente acuático. Por otra parte, entre los contaminantes de los sistemas acuáticos, se hallan los hidrocarburos aromáticos policíclicos (HAPs), algunos de los cuales son cancerígenos. Esta serie de compuestos en general está presente en el ambiente como mezclas complejas, presentando un rango muy variado de propiedades químicas, físicas y toxicológicas. En el presente trabajo, se estudió la interacción de sustancias húmicas con fenantreno y antraceno, separados o en mezcla, determinándose los coeficientes de partición (Koc) de las sustancias entre el carbono orgánico disuelto y la fase líquida por una metodología sencilla que utiliza extracción en fase sólida y determinación por espectrofotometría UV-visible. Los valores de Koc obtenidos son comparables con los referidos para estos compuestos por aplicación de otras técnicas. El método descrito es una herramienta que puede ser útil para analizar la interacción de los contaminantes orgánicos hidrofóbicos con las sustancias húmicas

Humic substances are major components of natural water. They are acidic polymers, mostly aromatic and usually harmless. However, they play an important role because they affect bioavailability and toxicity of many compounds in aquatic environments. Polycyclic aromatic hydrocarbons (some of them carcinogenic) are considered to be some of the most common pollutants of aquatic systems. They are usually found in the environment as complex mixtures exhibiting a wide range of physical, chemical and toxicological properties. In the present work, the interaction between humic substances and phenantrene and anthracene, individually or in mixtures, was studied. Partition coefficients of the substances between dissolved organic carbon and liquid phase were estimated by a simple methodology involving solid phase extraction and UVVIS spectrophotometry. Koc values obtained by this means are comparable with those obtained using other methods. The method described is a valuable tool for analyzing interactions of hydrophobic pollutants with humic substances

Agua en Iberoamérica, el de la limnología a la gestión en Sudamérica

Se muestra un panorama desde los estudios limnológicos de cuerpos de agua lénticos en Sudamérica, en particular, el problema de eutroficación, hasta las alternativas de manejo, a través de medidas estructurales y no estructurales

Agua en Iberoamérica, de la escasez a la desertificación

Describe la magnitud del problema de aridez de varios países y se presentan experiencias de manejo y gestión en tierras semiáridas y áridas, y posibles medidas estructurales y no estructurales orientadas a mitigar el efecto de la escasez de agua

Agua en Iberoamérica, funciones de los humedales, calidad de vida y agua segura

Presenta las visiones de los humedales iberoamericanos, y aspectos de la purificación y depuración de aguas para garantizar agua segura a la población

Agua en Iberoamérica, funciones de los humedales, calidad de vida y agua segura

Presenta las visiones de los humedales iberoamericanos, y aspectos de la purificación y depuración de aguas para garantizar agua segura a la población

Mesa redonda: calidad del agua - panorama regional

Cada uno de los tres expositores de Argentina, Chile y Brasil se refirieron a temas sobre la calidad del agua en sus respectivos países

Investigaciones en ciencias del agua: desafíos e interrogantes

El objetivo del presente trabajo es analizar los elementos que permitan caracterizar un eje entre la generación de conocimientos y la gestión del agua para consolidar un espacio de interacciones, compromisos y responsabilidades entre los actores implicados en ambos. En el marco de la relación entre ciencia y tecnología para la calidad de vida,que encierra interrelaciones e impactos,es que se debe analizar la relación entre generación de conocimientos y gestión del agua

Cardiolipin on the surface of apoptotic cells as a possible trigger for antiphospholipids antibodies.

This study provides evidence that cardiolipin (CL) molecules are expressed on the surface of apoptotic cells and are recognized by antiphospholipid antibodies, purified from patients with the antiphospholipid antibody syndrome (APS). CL expression on cell surface was demonstrated by high performance thin layer chromatography analysis of phospholipids from plasma membrane purified fractions and by the positive staining with the CL-specific dye nonyl-acridine orange. This finding was complemented with the observation that aCL IgG purified from patients with APS bind to the surface of apoptotic cells. This staining shows a clustered distribution mostly localized on surface blebs. Interestingly, CL exposure on the cell surface preceded the DNA fragmentation, as shown by cytofluorimetric analysis. These findings demonstrate that exposure of CL molecules on the cell plasma membrane is an early event of the apoptotic cellular program that may represent an in vivo trigger for the generation of aCL.

Agua en Iberoamérica, el sacuíferos, lagos y embalses

Reúne las visiones del estado del agua subterránea y de cuerpos lénticos como lagos y embalses en Iberoamérica

Aprovechamiento y gestión de recursos hídricos

Resume el panorama regional, sus fortalezas y debilidades, los objetivos para la integración, cooperación e intercambio y la interrelación entre los ejes: potabilización de aguas, vulnerabilidad de acuíferos, humedales y eutroficación de lagos y embalses. Posee una nómina de las universidades e institutos de la región con centros y grupos de investigación en recursos hídricos

Aprovechamiento y gestión de recursos hídricos

Resume el panorama regional, sus fortalezas y debilidades, los objetivos para la integración, cooperación e intercambio y la interrelación entre los ejes: potabilización de aguas, vulnerabilidad de acuíferos, humedales y eutroficación de lagos y embalses. Posee una nómina de las universidades e institutos de la región con centros y grupos de investigación en recursos hídricos

Frequency of development of acute global left ventricular dysfunction in human immunodeficiency virus infection.

OBJECTIVES: This study evaluated prospectively the frequency, clinical outcome and pathologic findings of acute global left ventricular dysfunction in human immunodeficiency virus (HIV) infection during the various stages of the disease. BACKGROUND: Acute global left ventricular dysfunction in the course of HIV infection is still a poorly defined clinical entity, and little is known about the outcome after the acute onset. METHODS: Between January 1988 and June 1992, 136 HIV-positive (HIV+) patients without clinical, electrocardiographic or echocardiographic evidence of cardiovascular dysfunction on admission were prospectively studied with serial echocardiograms. Patients were assigned to three groups: 1) anti-HIV+ asymptomatic (17 patients, 12.5%); 2) acquired immunodeficiency syndrome (AIDS)-related complex (26 patients, 19.1%); 3) AIDS (93 patients, 68.4%). RESULTS: During a mean follow-up period of 415 +/- 220 days, seven patients, all in the AIDS subgroup, developed clinical and echocardiographic findings of acute global left ventricular dysfunction; of these, six (85%) died of congestive heart failure. Mean survival time from symptom onset was 41 +/- 13 days. Necropsy findings in five patients revealed acute lymphocytic myocarditis in three, cryptococcal myocarditis in one and interstitial edema and fibrosis in one. In only one patient was left ventricular dysfunction reversible with treatment. CONCLUSIONS: Although infrequent, acute global left ventricular dysfunction is not rare in the course of HIV infection. It seems to occur exclusively during the AIDS stage. Acute global left ventricular dysfunction is often fatal but may be reversible and is mainly associated with the pathologic findings of acute myocarditis.

High cerebrospinal fluid and serum levels of tumor necrosis factor-alpha in asymptomatic HIV-1 seropositive individuals. Correlation with interleukin-2 and soluble IL-2 receptor.

The relationship between tumour necrosis factor-alpha (TNF-alpha) and the interleukin-2 (ILL-2) system in HIV-1 infection is important in understanding the dynamics of early immune response before the development of acquired immunodeficiency syndrome. Levels of TNF-alpha, IL-2 and soluble IL-2 receptor (sIL-2R) in serum and cerebrospinal fluid (CSF) samples from 31 asymptomatic HIV-1 seropositive individuals were measured. High levels of TNF-alpha were detected in CSF of 17 (55%) and serum of 22 (71%) subjects, 15 (88%) of whom had elevated CSF IL-2 levels and 16 (94%) had high sIL-2R levels. Moreover, CSF levels of TNF-alpha significantly correlated with CSF levels of IL-2 and sIL-2R. TNF-alpha, IL-2 and sIL-2R seem to be released within the intrathecal compartment early in the course of HIV-1 infection. In view of the known cytotoxic effects of TNF-alpha, an early release may contribute to subsequent development of neurological complications.

An unusual neurological feature of HIV-1 encephalopathy: Gerstmann's syndrome.

The authors describe the first case in literature of Gerstmann's syndrome (agraphia, acalculia, finger agnosia) occurred in HIV correlated encephalopathy developed as the first severe manifestation of HIV infection in a patient with prevalent white matter neuroradiologic alterations. The PDL rapidly extended from the left subcortical parietal-occipital regions to the pre-rolandic one, with subsequent involvement of the corpus calosum splenium and the bilateral temporal lobes white matter. The authors indicate the extent of the lesions and the involvement of the interhemispheric connection fibres as the pathogenetic mechanism of the "Gerstmann syndrome", that until today has not been reported in the literature of the wide variety of AIDS dementia complex. The administration of 1 g of zidovudine for about 9 months did not avoid the establishing of the neurologic damage, but the sudden suspension of the drug could have enhanced the exacerbation of inflammation and the involvement of areas whose lesion is classically believed responsible for cognitive impairment.