Abstract Randomness of fracture networks still makes channelized flow a challenge to track in hard-rock aquifers. While not underestimating geological and hydrological criteria that are also handled here through mapping exercises, this study raises an issue of water quality encountered in lifelong boreholes. Chemical classification checked against a recent conceptual model of bedrock aquifers gives birth to a new typology of groundwater in a complex granitic aquifer system located in the SW of Ivory Coast (West Africa). Major ion chemistry, borehole completion data, digital elevation model and satellite images are used to interpret the geochemical water facies as an expression of connexions between the saprolite and the saprock, or transient insulation. From major ions ratios, cumulate mineralization, carbonate equilibrium, stable isotopes, the maturation of ground waters and mixing between bedrock layers are described at seasonal and local scales. The results highlight some vertical feeding of the water table into the main saprock aquifer owing to shortcuts through the saprolite, along with the existence of dead-ends in the hydraulically active fracture network. Also, some influence of fault zones, either drain or barrier, is confirmed on the (Ca, Mg) bicarbonate water facies within the saprock.

Abstract The atmosphere of the Earth is a colloidal system that contains liquid and solid aerosol particles beside gas-phase components. Aerosol particles are ubiquitous and play an important role in the physics and chemistry of the atmosphere, especially in the lower 10–15-km layer, the troposphere. Above a turbulent layer that extends from the surface to an altitude of 1–2 km, the troposphere is filled with a homogeneous particle population that constitutes the background aerosol ( Junge, 1963 ). There is great scientific interest in atmospheric aerosols, stemming from a recognition of their significance in affecting our weather and climate. Aerosol particles change Earth’s heat balance both directly and indirectly. They scatter and absorb solar radiation, thereby modifying the planetary albedo; this is called the direct effect . Aerosol particles may act as cloud condensation nuclei (CCN), thereby modifying the physical and radiative properties of clouds; this is known as the indirect effect ( Fig. 1 ). The term radiative forcing refers to changes in the planetary radiation budget, caused by anthropogenic or external influences; it is measured in watts per square meter (Wm −2 ), and a positive value means net warming, whereas a negative value indicates net cooling of an air column above the Earth’s surface ( IPCC, 1996 ). In addition to being agents of climate change, aerosol particles affect our environment in various ways. For example, high concentrations of particles can cause serious visibility degradation; some particle types are notable for their contribution to atmospheric acidity, whereas other types are important because of their health effects.

Abstract Aerosol particles in the atmosphere interact with sunlight and initiate cloud formation, thereby affecting radiation transfer and modifying our climate. Aerosol particles also influence air quality and play important roles in various environmental processes. As the tropospheric aerosol is a heterogeneous mixture of various particle types, its climate and environmental effects can only be fully understood through detailed knowledge of the physical and chemical properties of the particles. Here, we review the formation and removal mechanisms of aerosol particles, the major approaches to study their physical and chemical properties, and discuss the most important categories of particle types. The focus of this review is on the ‘mineralogical’ identification and characterization of individual particles. We review the sources, transport and transformation mechanisms of the various particle types, their interactions with radiation and clouds, focusing on the results of the last 15 years. The Earth’s atmosphere is a colloidal system that contains liquid and solid aerosol particles as well as gas-phase components. Aerosol particles are ubiquitous and play an important role in the physics and chemistry of the atmosphere, especially in the lower 10–15-km layer, the troposphere. There is great scientific interest in atmospheric aerosols, stemming from a recognition of their significance in affecting our weather and climate. Aerosol particles control Earth’s radiative properties (‘heat balance’) both directly and indirectly. They scatter and/or absorb solar radiation, which is generally referred to as the aerosol ‘direct effect’. Aerosol particles also act as ‘cloud condensation nuclei’ (CCN), thereby modifying the physical and radiative properties of clouds; this is known as the ‘indirect effect’ (Fig. 1 ). The most important consequence of these two effects is the modification of the planetary albedo. The term ‘radiative forcing’ refers to changes in the planetary radiation budget, caused by anthropogenic or external influences; it is measured in watts per square meter (Wm −2 ), and a positive value means net warming, whereas a negative value indicates net cooling of an air column above the Earth’s surface ( Forster et al. , 2007 ). The importance of aerosol radiative effects is clearly indicated by the trend of solar radiation at the Earth’s surface. In the second half of the 20th century, a decline in incident solar radiation and an increase in planetary albedo were observed worldwide until about 1990. This phenomenon is referred to as ‘global dimming’, and is thought to have resulted from increasing aerosol forcing. After 1990, the trends changed signs and a brightening (a decrease in planetary albedo) occurred ( Wild et al. , 2005 ), probably resulting from a reduction of the global aerosol burden.