Riego con equipos presurizados

En un área de aprox. 2 000 000 ha del sur de Córdoba (Argentina) se evaluaron los equipos de riego con el fin de conocer su funcionamiento, el grado de uniformidad con que trabajan y la eficiencia de riego lograda por los productores. Se realizaron 21 evaluaciones sobre equipos operando de acuerdo con la programación establecida por sus usuarios; 14 sobre pivote, una sobre avance lateral, 4 sobre enrolladores (3 de cañón y uno de baja presión) y 2 sobre side roll. Los parámetros de calidad de riego brindaron coeficiente medio de uniformidad = 81,4 %, con uniformidad de distribución = 73,23 %. En el 80 % de los casos, la lámina aplicada fluctuó entre 10 y 20 mm siendo su promedio = 17 mm. De los resultados se puede inferir que -en general- la superficie asignada a cada equipo es siempre mayor que su capacidad para realizar oportunamente una óptima reposición del agua al suelo y que, si bien los coeficientes de uniformidad y distribución del agua pueden considerarse aceptables, la programación del riego es mala en todos los establecimientos evaluados poniéndose de manifiesto en la baja eficiencia de almacenamiento y repercutiendo directamente sobre la producción de los cultivos regados.

Cultural convergences in world wine consumption

This paper addresses the dynamics of world wine consumption over the past 50 years in 26 countries, verifying whether or not there is a macro-tendency towards a common consumption style, despite differences in taxation, economic policies and distribution systems among countries. From an empirical point of view, the σ and β convergence hypotheses were formally tested. Model results confirm the existence of both types of convergences. Per capita consumption of wine first experienced a reduction in differences between countries and then converged toward a central value. "Traditional" countries, with historically high levels of consumption, showed a decrease in wine consumption, while emerging countries with historically lower consumption levels showed an increase. These findings not only provide further support to the theory of international convergence of wine consumption on a volume basis, as already observed by other researchers in the European market, but they also offer support for the theory in major world markets. Furthermore, convergence appears to be happening not only at a quantitative level but at qualitative level as well, and this phenomenon may very well reflect the changing tastes of worldwide consumers towards a generalized structure of wine consumption.

Late Miocene-early Pliocene stable isotope record of benthic foraminifera from ODP Site 177-1088 in the sub-Antarctic South Atlantic

Benthic foraminiferal stable isotope records for the past 11 Myr from a recently drilled site in the sub-Antarctic South Atlantic (Site 1088, Ocean Drilling Program Leg 177, 41°S, 15°E, 2082 m water depth) provide, for the first time, a continuous long-term perspective on deep water distribution patterns and Southern Ocean climate change from the late Miocene through the early Pliocene. I have compiled published late Miocene through Pliocene stable isotope records to place the new South Atlantic record in a global framework. Carbon isotope gradients between the North Atlantic, South Atlantic, and Pacific indicate that a nutrient-depleted watermass, probably of North Atlantic origin, reached the sub-Antarctic South Atlantic after 6.6 Ma. By 6.0 Ma the relative proportion of the northern-provenance watermass was similar to today and by the early Pliocene it had increased to greater than the modern proportion suggesting that thermohaline overturn in the Atlantic was relatively strong prior to the early Pliocene interval of inferred climatic warmth. Site 1088 oxygen isotope values display a two-step increase between ~7.4 Ma and 6.9 Ma, a trend that parallels a published delta18O record of a site on the Atlantic coast of Morocco. This is perhaps best explained by a gradual cooling of watermasses that were sinking in the Southern Ocean. I speculate that relatively strong thermohaline overturn at rates comparable to the present day interglacial interval during the latest Miocene may have provided the initial conditions for early Pliocene climatic warmth. The impact of an emerging Central American Seaway on Atlantic-Pacific Ocean upper water exchange may have been felt in the North Atlantic beginning in the latest Miocene between 6.6 and 6.0 Ma, which would be ~1.5 Myr earlier than previously thought.

Seawater carbonate chemistry and survival, impairment of three phytoplankton species in a laboratory experiment

Sodium hypochlorite (NaOCl) is widely used to disinfect seawater in power plant cooling systems in order to reduce biofouling, and in ballast water treatment systems to prevent transport of exotic marine species. While the toxicity of NaOCl is expected to increase by ongoing ocean acidification, and many experimental studies have shown how algal calcification, photosynthesis and growth respond to ocean acidification, no studies have investigated the relationship between NaOCl toxicity and increased CO2. Therefore, we investigated whether the impacts of NaOCl on survival, chlorophyll a (Chl-a), and effective quantum yield in three marine phytoplankton belonging to different taxonomic classes are increased under high CO2 levels. Our results show that all biological parameters of the three species decreased under increasing NaOCl concentration, but increasing CO2 concentration alone (from 450 to 715 µatm) had no effect on any of these parameters in the organisms. However, due to the synergistic effects between NaOCl and CO2, the survival and Chl-a content in two of the species, Thalassiosira eccentrica and Heterosigma akashiwo, were significantly reduced under high CO2 when NaOCl was also elevated. The results show that combined exposure to high CO2 and NaOCl results in increasing toxicity of NaOCl in some marine phytoplankton. Consequently, greater caution with use of NaOCl will be required, as its use is widespread in coastal waters.

Composition of marine phosphorites and phosphate-bearing sediments

The book deals with behavior of phosphorus and its concentration in oceanic phosphorites. The major stages of marine geochemical cycle of phosphorus including its supply to sedimentary basins, precipitation from sea water, distribution and speciation in bottom sediments, diagenetic redistribution, and relation to other elements are under consideration. Formation of recent phosphorites as a culmination of phosphate accumulation in marine and oceanic sediments is examined. Distribution, structure, mineral and chemical compositions of major phosphorite deposits of various age on continental margins, as well as on submarine plateaus, uplifts and seamounts and some islands are described. A summary of trace element abundances in oceanic phosphorites is presented. Problems of phosphorite origin are discussed.