Managing Mediterranean soil resources under global change: expected trends and mitigation strategies

Regional Environmental Change - The soils of the Mediterranean Basin are the products of soil processes that have been governed by a unique convergence of highly differentiated natural and...     

Evolution of iron speciation during hydration of C4AF

It is now well accepted and demonstrated that calcium silicate, calcium aluminate and calcium sulfo aluminate (ettringite, AFm) phases exhibit a good capability to fix metals and metalloids. Unfortunately the role of minor phases and especially calcium-ferric aluminate phase, shorthand C4AF is not well defined. In other systems like in soils or sediments iron phases play a key role in the fixation of pollutant. In cement sorption isotherms, indicated that various metals can be retained by the C4AF hydrated products. Therefore the capabilities of those phase to retain heavy metal should not be neglected. Previous investigations have shown that the minerals formed during the hydration of C4AF are similar to those formed from C3A (pure tri-calcium aluminate) under comparable conditions. Nevertheless no investigation was conducted at the molecular level and there is still a controversy whether Fe substitutes for Al in the hydrated minerals in whole or in part, or if it forms FeOOH clusters scattered throughout the matrix. In this context we have conducted XAS experiments using synchrotron radiation. It was found that the hydration of C4AF forms C3AH6 (hydrogarnet) in which Fe randomly substitutes for Al as well as an amorphous FeOOH phase. Intermediate products like AFm (i.e., an ill organized lamellar phase) are also formed but rapidly evolve to C3AH6; iron does not seem to be incorporated in the AFm structure.     

Recent advances in physiological and molecular mechanisms of heavy metal accumulation in plants

Environmental Science and Pollution Research - Among abiotic stress, the toxicity of metals impacts negatively on plants’ growth and productivity. This toxicity promotes various perturbations...     

The impact of economic development on environmental degradation in Qatar

This study investigates the environmental Kuznets curve (EKC) hypothesis by employing the ecological footprint (EF) as an indicator of environmental degradation in Qatar over the 1980–2011 period. The results of the Autoregressive Distributed Lag (ARDL) estimation with structural breaks reveal that there is a long run relationship among the selected variables with a significant shift in the cointegration vector in 1996. The comparison of the short and long-run income elasticities indicates that the EKC hypothesis is not valid in Qatar. In particular, the long run effect of income is greater than its short run effect, which provides evidence of a monotonic relationship between EF and real GDP per capita. Moreover, the oil price and trade openness have a positive and negative long run impact on ecological footprint, respectively. We further investigate the robustness of the results by employing the Toda–Yamamoto causality tests and the estimation with regime approach. The outcome of TY shows that income and oil price increase significantly the ecological footprint. Moreover, the results of the estimation with two regimes (1980–1996 and 1997–2011) show that the impact of real GDP on the EF in the second regime is higher than the first regime, which confirm the ARDL estimation results.