Hydrogeochemistry and pollution effects of an aquifer in Quaternary loess like sediments in the land® lling area of Mar del Plata, Argentina

Sedimentos de tipo loÈssico cubren una superÆ cie aproximada de 1.800.000 km2 en la llanura Pampeana de Argentina, formando un sistema acuÌfero que es utilizado para abastecimiento de agua a ciudades y la poblaciÛn rural en la regiÛn. Este sistema acuÌfero suministra el agua que sustenta las actividades productivas que contribuyen en un 60% al producto bruto nacional. Es este trabajo se realiza un estudio detallado en un sector del acuÌfero prÛximo a la ciudad de Mar del Plata, provincia de Buenos Aires, en el que se localizan tres rellenos sanitarios. El principal objetivo es caracterizar los procesos geoquÌmicos que dan origen a la composiciÛn observada del agua subterr·nea. Se perforaron cinco pozos para la toma de muestras de agua y sedimentos, y evaluar el impacto de la inÆ ltraciÛn del lixiviado sobre esos procesos. Se determinÛ la composiciÛn textural y mineralÛgica de los sedimentos y la composiciÛn quÌmica del agua. Las relaciones de equilibrio entre la fase sÛlida y la soluciÛn se determinÛ utilizando programas especÌÆ cos. Se concluye que la composiciÛn quÌmica observada en la aguas es consecuencia principalmente de procesos de equilibrio con calcita e intercambio catiÛnico con adsorciÛn de calcio y liberaciÛn de sodio. La disoluciÛn de minerales de sÌlice amorfo, y la hidrÛlisis de silicatos en forma subordinada, da origen a altas concentraciones de sÌlice en las aguas. La mezcla con la inÆ ltraciÛn del lixiviado incrementa las concentraciones de los iones conservativos cloruro y nitrato, pero no se modiÆ can en general los procesos hidrogeoquÌmicos mayoritarios.Loess like sediments cover an area of about 1.800.000 km2 in the Pampa plain of Argentina, forming an aquifer system which is used for water supply for most of the cities an rural population in the region. This aquifer supplies water to agricultural productive activities that contribute to about a 60% of the national gross produce of the country. In this paper, detailed studies in a local sector of the aquifer near to Mar del Plata, in the land® lling area of the city, are performed. The main goal is to characterise the hydrogeochemical processes giving the chemical groundwater composition, and to analyze the impact of the in® ltration of the leachate from a neighbouring land® ll on some samples. Five wells were drilled to take sediments and water samples. The textural and mineralogical composition of the aquifer sediments was analysed and the chemical composition of groundwater was determined. The equilibrium relationship between the solid phase and groundwater was considered using speci® c computer codes. The achieved conclusions were that the chemical composition of groundwater is mainly due to calcite equilibrium and cationic exchange with calcium uptake and sodium release. The dissolution of amorphous silica minerals, and subordinate silicate hydrolysis, are responsible of the characteristic high dissolved silica concentrations. High chloride and nitrate contents result from leachate in® ltration, but the main geochemical processes in the mix are the same.Fil: Martinez, Daniel Emilio. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras; Argentina;Fil: Osterrieth, Margarita Luisa. Universidad Nacional de Mar del Plata. Facultad de Cs.exactas y Naturales. Instituto de Geologia de Costas y del Cuaternario; Argentina

Trichoderma koningii as a biomineralizing fungous agent of calcium oxalate crystals in typical Argiudolls of the Los Padres Lake natural reserve (Buenos Aires, Argentina)

The aim of the present study, performed on typical Argiudolls in a natural reserve with little or no anthropic impact, was to characterize the fungous biomineralizing process of calcium oxalate crystals in organic horizons of the soil. The chosen sites possessed different plant cover, identified as acacia woods and grassy meadows with particular micro environmental conditions that have differing effects in the process of biomineralization. The contribution of the plant material in the soil is a key factor since 1) it generates the particular composition of the organic horizons, 2) it determines the nature of decomposing organisms, and 3) it affects the presence, composition and development of biominerals. According to the results obtained, the acacia woods prove to be a site comparatively more favorable to the fungous biomineralizing process. This makes itself manifest in the greater abundance and development of crystals in the organic horizons of the soil, resulting in whewellite (CaC2O4 · H2O) and weddellite (CaC2O4 · (2 + x) H2O) regarding biomineral species developed, the latter being the major component. The observation of both species of biominerals is noteworthy since it represents the first cited in the country. The isolated fungous organisms were Trichoderma koningii, and Absidia corymbifera. T. koningii was identified as the most active biomineralizing organism thus constituting the first reference to indicate this species as a biomineral producing agent.Facultad de Ciencias Naturales y MuseoInstituto de Botánica "Dr. Carlos Spegazzini

Trichoderma koningii as a biomineralizing fungous agent of calcium oxalate crystals in typical Argiudolls of the Los Padres Lake natural reserve (Buenos Aires, Argentina)

The aim of the present study, performed on typical Argiudolls in a natural reserve with little or no anthropic impact, was to characterize the fungous biomineralizing process of calcium oxalate crystals in organic horizons of the soil. The chosen sites possessed different plant cover, identified as acacia woods and grassy meadows with particular micro environmental conditions that have differing effects in the process of biomineralization. The contribution of the plant material in the soil is a key factor since 1) it generates the particular composition of the organic horizons, 2) it determines the nature of decomposing organisms, and 3) it affects the presence, composition and development of biominerals. According to the results obtained, the acacia woods prove to be a site comparatively more favorable to the fungous biomineralizing process. This makes itself manifest in the greater abundance and development of crystals in the organic horizons of the soil, resulting in whewellite (CaC2O4 · H2O) and weddellite (CaC2O4 · (2 + x) H2O) regarding biomineral species developed, the latter being the major component. The observation of both species of biominerals is noteworthy since it represents the first cited in the country. The isolated fungous organisms were Trichoderma koningii, and Absidia corymbifera. T. koningii was identified as the most active biomineralizing organism thus constituting the first reference to indicate this species as a biomineral producing agent.Facultad de Ciencias Naturales y MuseoInstituto de Botánica "Dr. Carlos Spegazzini

Silica biomineralizations in Celtis tala (Celtidaceae)

Se estudió la asociación fitolítica de Celtis tala Planchon, su composición química y variabilidad morfológica, analizándose por separado los morfotipos presentes en hoja, tallo y fruto. La asociación fitolítica de Celtis tala está compuesta principalmente por cistolitos, fitolitos poliédricos articulados con paredes y/o lumen celular silicificados, y fitolitos de contorno irregular, superficie rugosa y lumen celular silicificado. Los análisis de EDAX y las observaciones al microscopio permitieron corroborar la presencia de biomineralizaciones de sílice y calcio en hoja, tallo y fruto. Además se detectaron otros elementos, como Mg, Al, K, P, Fe y S en algunos fitolitos. En particular, este trabajo revela la presencia de sílice como un componente fundamental en la estructura de los cistolitos en esta especie, apoyando los resultados obtenidos por otros autores para cistolitos en otras especies relacionadas. La presencia de un elemento mucho menos lábil que el carbonato de calcio, permite que estas estructuras luego de la descomposición de la materia orgánica, puedan permanecer durante más tiempo sin alterarse en el suelo, constituyendo importantes elementos indicadores de la presencia de Celtis tala en el registro fósil.Silica biomineralizations in Ce/tis tala (Celtidaceae). The phytolith assemblage of Ce/tis tala, its chemical composition and variability were studied. Leave, stem and fruit phytolith morphologies were analyzed with the purpose of establishing the contribution of each organ. The results showed that cystolith types, articulated poliedric (with wall and lumen silicified) and irregular, rugose poliedric phytoliths were the main morphologies present in Ce/tis tala phytolith assemblage. Silicon and calcium biomineralizations were detected by EDAX analysis and microscope observations in leave, stem and fruit. Other elements, such as Mg, Al, K, P, Fe aÍ1d S, were also detected by EDAX analysis in some phytoliths. The presence of silicon as an important structural cystolith component is detected in this study and supports the results obtained by other researchers for other species. The silicon cystolith constitution allows a long - term permanence of this morphology in sediment, and makes it an important Celtis tala indicator in fossil assemblagesFil: Fernández Honaine, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; ArgentinaFil: Zucol, Alejandro Fabián. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; ArgentinaFil: Osterrieth, Margarita Luisa. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; Argentin

Una técnica sencilla para la visualización de silicofitolitos en plantas mediante clarificación y montaje en aceite de inmersión

Background and aims: Different methodologies were proposed for the detection of silica deposits in plant tissues. These methodologies include dry and wet ashing (which destroy the surrounding tissue), phenol staining (toxic), safranin-crystal violet lactone and fast green-methyl red staining (not specific for silica), fluorescence microscopy, electronic microscopy, EDAX and Raman analyses (which involve expensive equipment). Here we presented an easy and cheap method based on tissue clearing and immersion oil mounting. M & M: We tested the methodology in longitudinal and cross sections of culms, leaves and roots of ten species that effectively accumulate silica. We applied different clearing techniques according to the type of plant material, we mounted in immersion oil and observed under light microscope. We compared the results with the ones obtained by traditional silicophytolith techniques. Results: Silica deposits were observed in all species and organs analyzed, and the observations were coincident with the results obtained by other techniques. It was also possible to identify calcium crystals, allowing the description of the most common biomineralizations produced by plants. Conclusions: The technique here proposed can be used for exploratory as well as for specific studies about the content and distribution of silicophytoliths in almost any tissue, organ and plant species. It can be applied in any laboratory, because it does not require expensive or hardly available equipment.Fil: Fernández Honaine, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Benvenuto, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Osterrieth, Margarita Luisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Amorphous silica biomineralizations in Schoenoplectus californicus (Cyperaceae): their relation with maturation stage and silica availability

The factors involved on the silicification process in Cyperaceae are scarcely known. In this study we analyse the effect of maturation stage and silica availability on the production of amorphous silica biomineralizations in culms of Schoenoplectus californicus. Young and senescent culms were collected from ponds with different silica availability. Two complementary methodologies (calcination and staining techniques), light and scanning electron microscopy and EDS were applied for amorphous silica analyses in plants. Quantitative data were analysed by Kruskal-Wallis and a two-way ANOVA tests. There were no significant differences between silica content of culms collected in ponds with different silica availability. Instead, silica content in senescent culms was higher than in young culms (F=91.43, P<0.01). Young culms only produce cone-shaped amorphous silica bodies, located in epidermal cells overlying sclerenchyma. Senescent culms produce a higher diversity of silicified cells, such as epidermal, stellate (aerenchyma) and parenchymatic cells. Silicification process in S. californicus is clearly affected by age and may act as a mechanism of structural resistance improvement. Some cells became silicified very early in the development and others may be silicified at a later stage depending on wall characteristics or rate of transpiration.Biomineralizaciones de sílice amorfo en Schoenoplectus californicus (Cyperaceae): su relación con el estado de maduración y la disponibilidad de sílice. Los factores involucrados en el proceso de silicificación en Cyperaceae son poco conocidos. En este estudio se analiza el efecto del estado de maduración y la disponibilidad de sílice en la producción de biomineralizaciones de sílice amorfo en tallos de Schoenoplectus californicus. Tallos jóvenes y senescentes fueron recolectados de lagunas con diferente disponibilidad de sílice. Dos técnicas complementarias (calcinación y tinción), microscopía óptica y electrónica y EDAX fueron aplicados para el análisis en las plantas. Los datos cuantitativos fueron analizados por tests de Kruskal-Wallis y ANOVA de dos vías. No hubo lagunas con diferente disponibilidad de sílice. En cambio, el contenido en tallos senescentes fue mayor que en los jóvenes (F=91,43; P<0,01). Los tallos jóvenes solo producen cuerpos silíceos cónicos, localizados en células epidérmicas asociadas al esclerénquima. En los tallos senescentes se silicifican una mayor diversidad de células, como las epidérmicas, del aerénquima y esclerénquima. El proceso de silicificación en S. californicus está claramente afectado por la edad y mejoraría la resistencia estructural. Algunas células se silicifican tempranamente, mientras que en otras depende de las características de la pared celular y/o de la tasa de transpiraciónFacultad de Ciencias Naturales y Muse

Differentiation of globular phytoliths in Arecaceae and other monocotyledons: morphological description for paleobotanical application

Globular phytoliths have been mainly assigned to palms, woody trees, and other monocotyledon families from tropical regions. The lack of detailed descriptions of this phytolith morphology and its correct assignments to particular groups could lead to erroneous interpretations of phytolith records. In order to improve paleobotanical interpretations of phytoliths records, we analyzed the phytolith content and described the quantitative and qualitative characters of globular phytoliths of Arecaceae, Bromeliaceae, Cannaceae, Marantaceae, Orchidaceae, Strelitziaceae, and Zingiberaceae species from Argentina. Phytoliths were extracted by calcination and multivariate analyses were used to analyze their taxonomic relevance. Phytolith assemblages allowed the differentiation 1) among Zingiberales species; 2) among Arecaceae species; 3) between Orchidaceae, Arecaceae, and Bromeliaceae families; and 4) between Zingiberales and the rest of the groups. The study of distinguishing features of globular morphologies (such as size, roundness, reniformity, number of spines, spine length, and density of spines) allowed the discrimination between two Arecaceae subfamilies, and among Bromeliaceae, Cannaceae, and Zingiberaceae families. This work showed the importance of both analyses (phytolith assemblages and phytolith morphometric) in the identification of groups at different levels and represented the first detailed and comparative description of globular phytoliths of palms and other monocotyledons from Argentina.Facultad de Ciencias Naturales y Muse

Estudio geológico integral de Punta Rasa, cabo San Antonio, provincia de Buenos Aires

Se describen características geomorfológicas, sedimentológicas, hidrológicas y pedológicas de la espiga arenosa de Punta Rasa (Cabo San Antonio, Buenos Aires), por medio del estudio aerofotográfico y perfiles topográficos. También se realizan aportes de significación en relación al clima, biota, erosión y evolución de la espiga y características físicas de la masa de agua próxima a la costa.Facultad de Ciencias Naturales y Muse

Trichoderma koningii as a biomineralizing fungous agent of calcium oxalate crystals in typical Argiudolls of the Los Padres Lake natural reserve (Buenos Aires, Argentina)

The aim of the present study, performed on typical Argiudolls in a natural reserve with little or no anthropic impact, was to characterize the fungous biomineralizing process of calcium oxalate crystals in organic horizons of the soil. The chosen sites possessed different plant cover, identified as acacia woods and grassy meadows with particular micro environmental conditions that have differing effects in the process of biomineralization. The contribution of the plant material in the soil is a key factor since 1) it generates the particular composition of the organic horizons, 2) it determines the nature of decomposing organisms, and 3) it affects the presence, composition and development of biominerals. According to the results obtained, the acacia woods prove to be a site comparatively more favorable to the fungous biomineralizing process. This makes itself manifest in the greater abundance and development of crystals in the organic horizons of the soil, resulting in whewellite (CaC2O4 · H2O) and weddellite (CaC2O4 · (2 + x) H2O) regarding biomineral species developed, the latter being the major component. The observation of both species of biominerals is noteworthy since it represents the first cited in the country. The isolated fungous organisms were Trichoderma koningii, and Absidia corymbifera. T. koningii was identified as the most active biomineralizing organism thus constituting the first reference to indicate this species as a biomineral producing agent.Facultad de Ciencias Naturales y MuseoInstituto de Botánica "Dr. Carlos Spegazzini

Estudio geológico integral de Punta Rasa, cabo San Antonio, provincia de Buenos Aires

Se describen características geomorfológicas, sedimentológicas, hidrológicas y pedológicas de la espiga arenosa de Punta Rasa (Cabo San Antonio, Buenos Aires), por medio del estudio aerofotográfico y perfiles topográficos. También se realizan aportes de significación en relación al clima, biota, erosión y evolución de la espiga y características físicas de la masa de agua próxima a la costa.Facultad de Ciencias Naturales y Muse