Analysis of climatic trends in data from the agrometeorological station of Bologna-Cadriano, Italy (1952–2007)

Agriculture is highly exposed to climate change, as farming activities directly depend on climatic conditions. Knowledge of the extent of such change and of related phenomena will help to answer the questions posed by society about adaptation strategies. The global situation is well described by the Fourth IPCC assessment report (IPCC 2007), but local studies are important to understand the impact and the priorities to adopt in adaptation strategies. In this study a historical set of meteorological data, collected during the period 1952–2007 at the University of Bologna (Italy) agrometeorological station, was analysed. Several indexes, such as Frost Severity Index, number of hot days, number of rainy days, etc., were calculated, and their trends in time were analysed. The results show a scenario of increasing temperatures and evapotranspiration, a decrease in rainy days and a deepening of the watertable. The effect of these changes on agriculture will be a decrease in water availability, an increase in heat stress in plants and an increase in drought risk.     

Millennial/centennial-scale thermocline ventilation changes in the Indian Ocean as reflected by aragonite preservation and geochemical variations in Arabian Sea sediments

The formation and temporal variability of the oxygen minimum zone (OMZ) of the Arabian Sea is a subject of intense research. We contribute to the discussion by studying modern seawater profiles of the Indian Ocean (salinity, O₂, pH, aragonite saturation, nitrate deficit, nutrients), which show that Subantarctic Mode and Antarctic Intermediate Waters (SAMW-AAIW) have a strong influence on the OMZ characteristics of the Arabian Sea. To obtain a better grasp of the range of possible OMZ variations, we studied a 50-kyr record in the NE Arabian Sea (core MD042876) from a site at 828 m water depth within the thermocline. In this core, aragonite is preserved during North Atlantic Heinrich events (HEs) and Dansgaard-Oeschger (DO) stadials, while it is absent during DO interstadials and most of the Holocene. Considering the excellent correlation between aragonite content and Sr/Ca ratio, as well as the presence of fine-grained aragonitic needles and the isotopic composition (δ¹³C) of carbonates in the fine fraction, we infer that essentially all aragonite originates as fine Sr-rich debris from shallow water. A comparison with other records from the NE Arabian Sea (Sr/Ca, δ¹⁵N) indicates that aragonite variability in the cores is rather controlled by OMZ intensity variations as forcing mechanism while changes in aragonite supply seem to play a minor role. The strong correlation of aragonite content with changes in millennial-scale ventilation of the Indian Ocean, as well as a comparison with modern oceanographic conditions, supports the theory that OMZ intensity variations are controlled by changes in the formation of SAMW-AAIW, and are not only due to monsoonal changes. Thus, during HEs and DO stadials, the thermocline Arabian Sea experienced a strengthened influx of O₂-rich SAMW-AAIW. On the other hand, OMZ conditions during DO interstadials and the Holocene seem best explained by analogy with the present-day situation: low supply of O₂ combined with elevated O₂ demand controlled by monsoon-related productivity.     

Polytypie und intraspezifische Evolution bei Süsswassertieren

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Bestrebungen zur Hebung des Unterrichts in Geologie auf Schulen und Hochschulen

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Bücher- und Zeitschriftenschau

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Professor Emil Philippi-Stiftung

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Bücher- und Zeitschriftenschau

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