2 research outputs found
Mediterranean springs: Keystone ecosystems and biodiversity refugia threatened by global change
Mediterranean spring ecosystems are unique habitats at the interface between surface water and groundwater. These ecosystems support a remarkable array of biodiversity and provide important ecological functions and ecosystem services. Spring ecosystems are influenced by abiotic, biotic, and anthropogenic factors such as the lithology of their draining aquifers, their climate, and the land use of their recharge area, all of which affect the water chemistry of the aquifer and the spring discharges. One of the most relevant characteristics of spring ecosystems is the temporal stability of environmental conditions, including physicochemical features of the spring water, across seasons and years. This stability allows a wide range of species to benefit from these ecosystems (particularly during dry periods), fostering an unusually high number of endemic species. However, global change poses important threats to these freshwater ecosystems. Changes in temperature, evapotranspiration, and precipitation patterns can alter the water balance and chemistry of spring water. Eutrophication due to agricultural practices and emergent pollutants, such as pharmaceuticals, personal care products, and pesticides, is also a growing concern for the preservation of spring biodiversity. Here, we provide a synthesis of the main characteristics and functioning of Mediterranean spring ecosystems. We then describe their ecological value and biodiversity patterns and highlight the main risks these ecosystems face. Moreover, we identify existing knowledge gaps to guide future research in order to fully uncover the hidden biodiversity within these habitats and understand the main drivers that govern them. Finally, we provide a brief summary of recommended actions that should be taken to effectively manage and preserve Mediterranean spring ecosystems for future generations. Even though studies on Mediterranean spring ecosystems are still scarce, our review shows there are sufficient data to conclude that their future viability as functional ecosystems is under severe threat.Mediterranean spring ecosystems are unique habitats supporting a remarkable array of biodiversity and providing important ecological functions and ecosystem services. However, global change poses important threats to these freshwater ecosystems, such as changes in climate patterns and increasing human pressures like overexploitation and pollution. We provide a synthesis of the main characteristics and functioning of Mediterranean spring ecosystems and their threats due to global change.imag
SANS behaviour of Fe<sub>91</sub>Zr<sub>9</sub> glass under magnetic field
Zero-field and in-field small-angle neutron scattering measurements over a wide Q range are presented for the
Fe91Zr9 metallic glass in the 10-290 K range. Two transitions observed at 210 K and around 60 K are
related to Tc and reentrant transition temperature, respectively. The spectra (0.003 Å-1 < Q< 0.5
Å-1) reveal the existence of an important contribution at the lowest Q values and at least two humps in the entire curves.
The application of the magnetic field results in an anisotropic signal, and a global decrease of intensity. The magnetic field drastically reduces
I(Q) in the region for Q<0.04 Å-1, but not so strongly at larger Q values (even at H=4 T), becoming more evident a
remaining hump. Its origin can so far be uniquely explained by the models dealing with the existence of clusters embedded in a ferromagnetic
matrix