The Anthropocene: From Global Change to Planetary Stewardship

Over the past century, the total material wealth of humanity has been enhanced. However, in the twenty-first century, we face scarcity in critical resources, the degradation of ecosystem services, and the erosion of the planet's capability to absorb our wastes. Equity issues remain stubbornly difficult to solve. This situation is novel in its speed, its global scale and its threat to the resilience of the Earth System. The advent of the Anthropence, the time interval in which human activities now rival global geophysical processes, suggests that we need to fundamentally alter our relationship with the planet we inhabit. Many approaches could be adopted, ranging from geoengineering solutions that purposefully manipulate parts of the Earth System to becoming active stewards of our own life support system. The Anthropocene is a reminder that the Holocene, during which complex human societies have developed, has been a stable, accommodating environment and is the only state of the Earth System that we know for sure can support contemporary society. The need to achieve effective planetary stewardship is urgent. As we go further into the Anthropocene, we risk driving the Earth System onto a trajectory toward more hostile states from which we cannot easily return.     

Geostatistical analysis to identify hydrogeochemical processes in complex aquifers: a case study (Aguadulce unit, Almeria, SE Spain)

The Aguadulce aquifer unit in southeastern Spain is a complex hydrogeological system because of the varied lithology of the aquifer strata and the variability of the processes that can take place within the unit. Factorial analysis of the data allowed the number of variables to be reduced to 3 factors, which were found to be related to such physico-chemical processes as marine intrusion and leaching of saline deposits. Variographic analysis was applied to these factors, culminating in a study of spatial distribution using ordinary kriging. Mapping of the factors allowed rapid differentiation of some of the processes that affect the waters of the Gador carbonate aquifer within the Aguadulce unit, without the need to recur to purely hydrogeochemical techniques. The results indicate the existence of several factors related to salinity: marine intrusion, paleowaters, and/or leaching of marls and evaporitic deposits. The techniques employed are effective, and the results conform to those obtained using hydrogeochemical methods (vertical records of conductivity and temperature, ion ratios, and others). The findings of this study confirm that the application of such analytical methods can provide a useful assessment of factors affecting groundwater composition.     

Use of non-homogeneous Poisson process (NHPP) in presence of change-points to analyze drought periods: a case study in Brazil

Rain precipitation in the last years has been very atypical in different regions of the world, possibly, due to climate changes. We analyze Standard Precipitation Index (SPI) measures (1, 3, 6 and 12-month timescales) for a large city in Brazil: Campinas located in the southeast region of Brazil, São Paulo State, ranging from January 01, 1947 to May 01, 2011. A Bayesian analysis of non-homogeneous Poisson processes in presence or not of change-points is developed using Markov Chain Monte Carlo methods in the data analysis. We consider a special class of models: the power law process. We also discuss some discrimination methods for the choice of the better model to be used for the rain precipitation data.     

Removal of the emerging contaminant bisphenol A by an ureasil–PEO hybrid membrane: experimental study and molecular dynamic simulation

This work reports the use of a cross-linked ureasil–PEO hybrid matrix (designated PEO800) as an efficient adsorbent to retain the emerging contaminant bisphenol A (BPA) from an aqueous medium. The in-deep experimental and theoretical results provide information about the interactions between PEO800 and BPA. The in situ UV-vis spectroscopy data and the pseudo-first order, pseudo-second order, Elovich, and Morris–Webber intraparticle diffusion models allowed us to propose a three-step mechanism for the adsorption of BPA onto PEO800. The results indicate that the pseudo-first-order kinetic model effectively describes the adsorption of BPA onto PEO800. Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy confirmed the interaction of PEO800 with BPA, showing an alteration in the chemical environment of the polymer ether oxygen atoms present in the hybrid matrix. The molecular dynamic simulation provides further evidence that the BPA molecules interact preferentially with PEO. The amount of desorbed BPA depended on the pH and solvent used in the assays. This work provides new opportunities for using the hydrophilic ureasil–PEO matrix which has demonstrated its abilities in being a fast and easy alternative to successfully removing organic contaminants from aqueous mediums and therefore having potential applications in water remediation.

Graphical abstract