Mobility, Turnover and Storage of Pollutants in Soils, Sediments and Waters: Achievements and Results of the EU Project AquaTerra - A Review

Abstract

-AquaTerra is one of the first environmental projects within the 6th Framework program by the European Commission. It began in June 2004 with a multidisciplinary team of 45 partner organizations from 13 EU countries, Switzerland, Serbia, Romania and Montenegro. Results from sampling and modeling in 4 large river basins (Ebro, Danube, Elbe and Meuse) and one catchment of the Brévilles Spring in France led to new evaluations of diffuse and hotspot input of persistent organic and metal pollutants including dynamics of pesticides and polycyclic aromatic hydrocarbons, as well as metal turnover and accumulation. While degradation of selected organic compounds could be demonstrated under controlled conditions in the laboratory, turnover of most persistent pollutants in the field seems to range from decades to centuries. First investigations of long-term cumulative and degradation effects, particularly in the context of climate change, have shown that it is also necessary to consider the predictions of more than one climate model when trying to assess future impacts. This is largely controlled by uncertainties in climate model responses. It is becoming evident, however, that changes to the climate will have important impacts on the diffusion and degradation of pollutants in space and time that are just at the start of their exploration.contaminants / organic / inorganic / European river basins / climate change / sorption / biodegradation / soil / sediment / ground-and surface water / heavy metals / review / pesticides / atrazine / isoproturon / alkyphenol / acetochlor / chlortoluron / organochlorine / Br diphenyl ethers / drugs / TOF mass spectrometry / 87Sr * Corresponding author: johannes.barth@uni-tuebingen.de 2 J.A.C. Barth et al.

Redox reactions of selenium as catalyzed by magnetite: Lessons learned from using electrochemistry and spectroscopic methods

“…This is not only the case in an experimental setup like the one at the interface of a powder microelectrode but also in redox active environments (e.g., soils) where microporous clay aggregates are in contact with flow-through macro cracks. Since the potential of a redox transition is typically pH-dependent, this means, in turn, that the pH gradient also leads to a peak broadening with more solution-like pH values right at the interface and higher/lower pH values further away for reduction/oxidation reactions while the magnitude of the gradient is dependent on pore size and diffusion times (Barth et al, 2009;Borch et al, 2010). It would be challenging to measure and quantify those pH gradients that take place at a micrometer scale in a total volume on the order of tens of microns across, which is even below the size and resolution of pH microelectrodes.…”

On–Off Mobilization of Contaminants in Soils during Redox Oscillations

“…Wetlands and flood plain soils can act as sinks for metals (e.g., Cr, Cu, Pb), actinides (e.g., U), metalloids (e.g., As, Sb) and nonmetals (e.g., Se). These trace elements accumulate in such soils, sediments, and wetlands up to a few thousand μg g –1 , as a result of historical mining activities, dam tailing failure, and long-term weathering. − Natural wetlands have proven so successful at removing nutrients and contaminants from wastewater that, in the last decades, engineered systems such as constructed wetlands have been introduced as barriers between natural aquatic ecosystems and industrialized zones. This is a promising strategy to limit contaminant fluxes to the aquatic environment and control pollution .…”

“…However, sediments that act as sinks for inorganic contaminants may also release them under varying hydraulic regimes . The efficiency of wetlands, as well as the capacity of periodically flooded soils to sequester trace elements, depends on climatic factors such as flooding and drought; such factors are predicted to become more severe under climate change …”

Arsenic Species Formed from Arsenopyrite Weathering along a Contamination Gradient in Circumneutral River Floodplain Soils

“…In many industrialized regions worldwide, riverine floodplains have accumulated legacies of toxic trace metals (e.g., Cd, Zn, Pb, Cu, Hg) and metalloids (e.g., As, Sb). These contaminations mainly arise from past or present mining and ore processing, releasing dissolved metal(loid)s and/or their mineral host phases into downstream floodplains by mine waste discharge or tailings dam failures. , In contrast to most mine tailings piles and impoundments, river floodplains cover extensive areas and are often used for settlements and agriculture, increasing the chance for human exposure. Even moderate concentrations of inorganic contaminants in soils can pose a threat to soil fertility and ecosystem health, if the contaminants are partly available to soil microorganisms and plants and may thus enter the food chain .…”