Leandro Mastrantonio

Arsenic and trace elements in soil, water, grapevine and onion in Jáchal, Argentina

Contamination by trace elements (TE) is an increasing concern worldwide. In some areas, crop production could be limited by the presence of metals and metalloids, so it is important to determine their concentrations and mobility. The region of Jáchal, province of San Juan, Argentina, has good growing conditions for onion and grapevine production, but their quality and yield are affected by high TE concentration in soils and water. Soils, water, grapevine and onion were sampled and TE content determined. In soils elevated As, B, Cr, Hg, and Tl concentrations were detected (506±46, 149±3, 2714±217, 16±7, and 12±3μgg-1, respectively, for maximum values measured), and physicochemical properties of the soil promotes these elements mobility. Water samples had high As, B, Cr, and Fe concentrations (1438±400, 10,871±471, 11,516±2363, and 3071±257μgL-1, respectively, for maximum values measured) while in onion bulbs and grapevine berries, As, Cr, Cu, and Fe (92±7 and 171±20, 1412±18 and 2965±32, 17±3 and 126±88, and 418±204 and 377±213μgg-1, respectively, for maximum values measured) exceeded the limits for food consumption established by Argentinian law. Correlation analyses indicated that: i) there is a common source of TE in this area, ii) each elements concentration in plants is associated with different soil variables and different soils depths, and iii) the lack of correlation between soil and water indicates that concentration in water is not constant over the time and/or there exists a differential accumulation of elements in soils depending on their own properties. Data obtained demonstrate very high concentration of TE in soil, grapevines, and onion plants in Jáchal region, and different remediation techniques are necessary to stabilize and minimize the bioavailability of these elements.

Fine roots of Prosopis flexuosa trees in the field. Plant and soil variables that control their growth and depth distribution

Fine root growth in natural vegetation is difficult to predict due to its regulation by soil and plant factors. Field studies in arid ecosystems show a variety of root responses to soil resources and to plant aboveground phenology that sometimes differ from root responses predicted by controlled experiments. There is a pressing need to cover a greater diversity of plant species and ecological scenarios in field studies. In this paper, we have studied fine roots of Prosopis flexuosa trees living with or without access to phreatic water in an inter-dune valley and a dune flank, respectively, in the Central Monte Desert, Argentina. We have described fine root growth over time and at different depths by rhizotron observations and soil core auger samples in relation to soil water and nutrients, tree crown phenology, plant water and nutrient status. We have found that surface soil moisture from rainfall is the variable that best predicts seasonal topsoil fine root growth. Access to groundwater advanced leaf sprouting with respect to rainfall, but did not advance root growth that stayed linked to rainfall in valley and dune flank trees. Trees without access to phreatic water produced deeper and thicker or denser roots, which is consistent with the poor soil resource content of dunes. Variations in rainfall dynamics due to global climate change may have a particular impact on fine roots and ecosystem processes such as biogeochemistry and carbon budget in dune flank trees as well as in valley trees.

Evaluación biofísica de servicios ecosistémicos en la cuenca del Arroyo Grande, Tunuyán, Mendoza

La cuenca del Arroyo Grande (Valle de Uco, Tunuyan, Mendoza) es un area que presenta cambios clave en el uso de sus recursos, producidos principalmente por los nuevos emprendimientos vitivinicolas y facilitados por la aplicacion del riego presurizado. En estos cambios primo la decision privada y la diversidad de criterios de gestion ambiental. Con el objetivo de evaluar la capacidad funcional de los dos ecosistemas principales, el monte nativo y el agroecosistema, y la provision relativa de servicios ecosistemicos (SE) en la cuenca del Arroyo Grande, se aplico una metodologia basada en el protocolo ECOSER 1.0 mediante un sistema de informacion geografica. A partir de informacion biofisica del area se ubicaron en el espacio los tipos de ecosistemas dominantes (TED) y se consideraron cuatro funciones ecosistemicas (FE). La identificacion de cada SE y su provision relativa se calculo como la combinacion lineal del flujo de cada FE ponderado por su aporte relativo al correspondiente SE. Por ultimo, la provision de SE se evaluo espacialmente mediante la generacion de mapas. Los resultados muestran al agroecosistema como proveedor de un mayor numero de SE, dentro de los ocho analizados. Entre ellos figura la produccion agricola, que incluye cultivos, ganado y forestacion. El monte nativo provee en mayor proporcion SE de soporte y aprovisionamiento, relacionados con la provision de agua y su calidad, que a su vez son esenciales para el agroecosistema. En conclusion, existen diferencias en la provision de SE segun los ecosistemas, y aquellos que brinda el agroecosistema dependen de otros SE, proporcionados antes por el monte nativo. https://doi.org/10.25260/EA.17.27.1.1.305