Scenario analysis for nutrient emission reduction in the European inland waters

International audienceDespite a large body of legislation, high nutrient loads are still emitted in European inland waters. In the present study we evaluate a set of alternative scenarios aiming at reducing nitrogen and phosphorus emissions from anthropogenic activities to all European Seas. In particular, we tested the full implementation of the European Urban Waste Water Directive, which controls emissions from point source. In addition, we associated the full implementation of this Directive with a ban of phosphorus-based laundry detergents. Then we tested two human diet scenarios and their impacts on nutrient emissions. We also developed a scenario based on an optimal use of organic manure. The impacts of all our scenarios were evaluated using a statistical model of nitrogen and phosphorus fate (GREEN) linked to an agro-economic model (CAPRI). We show that the ban of phosphorus-based laundry detergents coupled with the full implementation of the Urban Waste Water Directive is the most effective approach for reducing phosphorus emissions from human based activities. Concerning nitrogen, the highest reductions are obtained with the optimized use of organic manure

Thallium isotopes in early diagenetic pyrite – a paleoredox proxy?

Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 75 (2011): 6690-6704, doi:10.1016/j.gca.2011.07.047.This paper presents the first study of Tl isotopes in early diagenetic pyrite. Measurements from two sections deposited during the Toarcian Ocean Anoxic Event (T-OAE, ~183Ma) are compared with data from Late Neogene (<10Ma) pyrite samples from ODP legs 165 and 167 that were deposited in relatively oxic marine environments. The Tl isotope compositions of Late Neogene pyrites are all significantly heavier than seawater, which most likely indicates that Tl in diagenetic pyrite is partially sourced from ferromanganese oxy-hydroxides that are known to display relatively heavy Tl isotope signatures. One of the T-OAE sections from Peniche in Portugal displays pyrite thallium isotope compositions indistinguishable from Late Neogene samples, whereas samples from Yorkshire in the UK are depleted in the heavy isotope of Tl. These lighter compositions are best explained by the lack of ferromanganese precipitation at the sediment–water interface due the sulphidic (euxinic) conditions thought to be prevalent in the Cleveland Basin where the Yorkshire section was deposited. The heavier signatures in the Peniche samples appear to result from an oxic water column that enabled precipitation of ferromanganese oxy-hydroxides at the sediment–water interface. The Tl isotope profile from Yorkshire is also compared with previously published molybdenum isotope ratios determined on the same sedimentary succession. There is a suggestion of an anti-correlation between these two isotope systems, which is consistent with the expected isotope shifts that occur in seawater when marine oxic (ferromanganese minerals) fluxes fluctuate. The results outlined here represent the first evidence that Tl isotopes in early diagenetic pyrite have potential to reveal variations in past ocean oxygenation on a local scale and potentially also for global oceans. However, much more information about Tl isotopes in different marine environments, especially in anoxic/euxinic basins, is needed before Tl isotopes can be confidently utilized as a paleo-redox tracer.SGN is funded by a NERC fellowship

The water footprint of agricultural products in European river basins

This work quantifies the agricultural water footprint (WF) of production (WF _prod, agr ) and consumption (WF _cons, agr ) and the resulting net virtual water import (netVW _i, agr ) of 365 European river basins for a reference period (REF, 1996–2005) and two diet scenarios (a healthy diet based upon food-based dietary guidelines (HEALTHY) and a vegetarian (VEG) diet). In addition to total (tot) amounts, a differentiation is also made between the green (gn), blue (bl) and grey (gy) components. River basins where the REF WF _cons, agr, tot exceeds the WF _prod, agr, tot (resulting in positive netVW _i, agr, tot values), are found along the London–Milan axis. These include the Thames, Scheldt, Meuse, Seine, Rhine and Po basins. River basins where the WF _prod, agr, tot exceeds the WF _cons, agr, tot are found in Western France, the Iberian Peninsula and the Baltic region. These include the Loire, Ebro and Nemunas basins. Under the HEALTHY diet scenario, the WF _cons, agr, tot of most river basins decreases (max −32%), although it was found to increase in some basins in northern and eastern Europe. This results in 22 river basins, including the Danube, shifting from being net VW importers to being net VW exporters. A reduction (max −46%) in WF _cons, agr, tot is observed for all but one river basin under the VEG diet scenario. In total, 50 river basins shift from being net VW importers to being net exporters, including the Danube, Seine, Rhone and Elbe basins. Similar observations are made when only the gn + bl and gn components are assessed. When analysing only the bl component, a different river basin pattern is observed

Role of humic acids in the TiO(2)-photocatalyzed degradation of tetrachloroethene in water

The effect of humic acids on the TiO(2)-mediated photocatalytic degradation of tetrachloroethene (PCE) was kinetically investigated at different pH and initial substrate concentrations. The pro cess occurs through two parallel paths: a major oxidative route leading to mineralization and a reductive route leading to the formation of dichloroacetic acid (DCAA), also undergoing photodegradation. The rate of PCE decomposition was found to decrease in the presence of humic acids adsorbed on the semiconductor surface, while the concentration of the intermediate dichloroacetic acid increased. This is a consequence of the scavenging action bf humic acids toward photoproduced surface oxidant species, which makes conduction band electrons more easily available for interface reactions. Kinetic studies on the effect of humic acids in the TiO(2)-mediated photodegradation of dichloroacetic acid showed that the progressively greater accumulation of this highly toxic intermediate, observed with increasing humic acids content, was a consequence of both an increase in the rate of its production from PCE and a decrease in the rate of its oxidative photodegradation. (C) 1999 Elsevier Science Ltd. All rights reserved

Humic acid-sensitized photoreduction of Cr(VI) on ZnO particles

The possibility that humic acids act as sensitizers in the photoinduced reduction of Cr(VI) to Cr(III) in aqueous suspensions containing ZnO particles was verified. Equilibrium sorption studies showed that Cr(III) is totally adsorbed on ZnO, while Cr(VI) adsorption on ZnO is very low. Solar irradiation of the ZnO suspensions induced the photoreduction of Cr(VI), leading to a marked increase of the amount of chromium adsorbed on the mineral oxide. The yield of the reaction is enhanced both in the presence of humic acids and under anoxic conditions. Humic acids adsorbed onto the oxide surface sensitize Cr(VI) photoreduction and the competitive photoreduction of molecular oxygen leading to hydrogen peroxide

Potential water saving through changes in European diets

This study quantifies the water footprint of consumption (WFcons) regarding agricultural products for three diets – the current diet (REF), a healthy diet (HEALTHY) and a vegetarian diet (VEG) – for the four EU zones WEST, NORTH, SOUTH and EAST. The WFcons related to the consumption of agricultural products (4265 l per capita per day or lcd) accounts for 89% of the EU's total WFcons (4815 lcd). The effect of diet has therefore an essential impact on the total WFcons. The current zonal WFcons regarding agricultural products is: 5875 lcd (SOUTH), 4053 lcd (EAST), 3761 lcd (WEST) and 3197 lcd (NORTH). These differences are the result of different consumption behaviours as well as different agricultural production methods and conditions. From the perspective of a healthy diet based on regional dietary guidelines, the intake of several product groups (sugar, crop oils, animal fats and meat) should be decreased and increased for others (vegetables, fruit). The WFcons regarding agricultural products for the alternative diets are the following: HEALTHY 4110 lcd (− 30%) and VEG 3476 lcd (− 41%) for SOUTH; HEALTHY 3606 lcd (− 11%) and VEG 2956 lcd (− 27%) for EAST; HEALTHY 2766 lcd (− 26%) and VEG 2208 lcd (− 41%) for WEST; HEALTHY 3091 lcd (− 3%) and VEG 2166 lcd (− 32%) for NORTH. Both the healthy and vegetarian diets thus result – consistent for all zones – in substantial WFcons reductions. The largest reduction takes place for the vegetarian diet. Indeed, a lot of water can be saved by EU citizens by a change in their diet