Impact of climate change on groundwater point discharge: backflooding of karstic springs (Loiret, France)

Under certain hydrological conditions it is possible for spring flow in karst systems to be reversed. When this occurs, the resulting invasion by surface water, i.e. the backflooding, represents a serious threat to groundwater quality because the surface water could well be contaminated. Here we examine the possible impact of future climate change on the occurrences of backflooding in a specific karst system, having first established the occurrence of such events in the selected study area over the past 40 years. It would appear that backflooding has been more frequent since the 1980s, and that it is apparently linked to river flow variability on the pluri-annual scale. The avenue that we adopt here for studying recent and future variations of these events is based on a downscaling algorithm relating large-scale atmospheric circulation to local precipitation spatial patterns. The large-scale atmospheric circulation is viewed as a set of quasi-stationary and recurrent states, called weather types, and its variability as the transition between them. Based on a set of climate model projections, simulated changes in weather-type occurrence for the end of the century suggests that backflooding events can be expected to decrease in 2075–2099. If such is the case, then the potential risk for groundwater quality in the area will be greatly reduced compared to the current situation. Finally, our results also show the potential interest of the weather-type based downscaling approach for examining the impact of climate change on hydrological systems

Rhodium(II)‐Catalyzed Selective C(sp 3 )−H Amination of Alkanes

International audienceAbstract The development of an efficient catalytic system enabling the conversion of alkanes to valuable nitrogen‐containing building blocks is reported. Light alkanes can be selectively functionalized by an intermolecular C(sp 3 )−H amination reaction that proceeds at room temperature in the presence of only 1 mol % of a dirhodium(II) complex. Selective amination of tertiary C(sp 3 )−H within acyclic or cyclic alkanes used as limiting components leads to the corresponding amides isolated with yields in the 51–96 % range. The reaction, that can be performed on a gram‐scale, applies with equal levels of efficiency and selectivity to more complex hydrocarbons

A educação infantil e a questão da escola: o caso da França

Nos últimos trinta anos, a prioridade dada a uma lógica escolar para justificar a pré-escola coincide com uma dupla mudança na instituição. A primeira diz respeito às relações que a escola maternal mantém com a escolarização obrigatória e com as estruturas de cuidados para as crianças pequenas. A outra refere-se às reformas do currículo escolar e ao desenvolvimento dos processos de avaliação. A escola maternal, local de acolhimento, de cuidados e de preparação para a escola, tornou-se institucionalmente uma verdadeira escola. A difusão das comparações internacionais contribuiu para essas mudanças