Impact of crystalline and amorphous iron- and aluminum hydroxides on mechanisms of phosphate adsorption and desorption

Fourier-transform infrared(FT-IR) spectroscopic experiments were carried out during phosphate adsorption on highly crystalline gibbsite, poorly crystalline 2-line-ferrihydrite and amorphous iron–aluminum–hydroxide mixtures in the molar ratio 1:0, 10:1, 5:1, 1:1, 1:5, 1:10 and 0:1. The OH stretching vibrational bands were utilized to analyze changes in structural and surface OH groups during adsorption, because the position of characteristic P\O vibrational bands can shift depending on reaction conditions, pH or adsorbed phosphate content.Adsorption and desorption kinetics were studied at pH6 and different initial phosphate concentrations to achieve varying phosphate coverage on the mineral surfaces. For gibbsite the formation of AlHPO_4 and Al_2HPO_4 can be assumed, while for ferrihydrite, a FeHPO_4 or Fe_2PO_4 complex and the precipitation of FePO_4 with longer equilibration time were proposed.Fe_2HPO_4 or a Fe_2PO_4 surface complex was deduced for Fe-hydroxides, an AlH_2PO_4 surface complex was identified for Al-hydroxide, and both displayed either hydrogen bonds to neighboring hydroxyl groups or hydrogen bonds to outer-sphere complexes. Fe:Al-hydroxide mixtures with high Al ratios showed a low phosphate desorption rate, while ferrihydrite and the Fe:Al-hydroxide mixtures with high Fe ratios had almost negligible desorption rates. It was concluded that within the weakly associated amorphous FeO(OH) materials, FePO_4 precipitated, which was bound by outer-sphere hydrogen bonds. With high Al ratios, desorption increased, which indicated weaker phosphate binding of both inner-sphere and outer-sphere complexes and hence, either no or minor quantities of precipitate. Ferrihydrite showed a more rigid structure and a lower extent of precipitation compared to amorphous Fe-hydroxide.     

Occurrence, fate and assessment of polar metamizole (dipyrone) residues in hospital and municipal wastewater

The occurrence and fate of residues from the therapeutic use of the non-steroidal anti-inflammatory drug metamizole have been studied in investigations of sewage effluents from a military hospital, municipal sewers and a sewage treatment plant (STP) in Berlin, Germany. The loads of the metabolites aminoantipyrin (AA), 4-acetylaminoantipyrin (AAA) and 4-formyl-aminoantipyrin (FAA), rapidly formed after the application of metamizole, were predicted from pharmacokinetic data and based on the evaluation of extensive data sets of on the administration in hospitals and private households. In parallel, the actual concentrations were measured within three field trials. For the military hospital, the estimated average annual discharges of AA/AAA and FAA were 10.5 and 3.2 kg, respectively. For the STP, annual loads of 333 and 133 kg were determined for AA/AAA and FAA, respectively. During sewage treatment, an average decrease of 26% of the loads was measured for AA/AAA whereas no changes were observed for FAA. Generally, the prediction of the loads resulted in an overestimation of the residue levels compared to those measured in the respective sewers. Thus, modeling of predicted loads or concentrations alone will not be sufficient for a realistic assessment. Concerns for human or other mammals' health are not expected from the occurrence of metamizole residues in the aquatic system measured at concentrations up to 7 microg l(-1) in STP effluents. However, a rest of uncertainty remains as it was not possible to derive a no observed effect level for the induction of rare but potentially fatal toxicological side effects reported for metamizole.     

Precision,accuracy, and application of diver-towed underwater GPS receivers

Diver-towed global positioning systems (GPS) handhelds have been used for a few years in underwater monitoring studies. We modeled the accuracy of this method using the software KABKURR originally developed by the University of Rostock for fishing and marine engineering. Additionally, three field experiments were conducted to estimate the precision of the method and apply it in the field: (1) an experiment of underwater transects from 5 to 35 m in the Southern Chile fjord region, (2) a transect from 5 to 30 m under extreme climatic conditions in the Antarctic, and (3) an underwater tracking experiment at Lake Ranco, Southern Chile. The coiled cable length in relation to water depth is the main error source besides the signal quality of the GPS under calm weather conditions. The forces used in the model resulted in a displacement of 2.3 m in a depth of 5 m, 3.2 m at a 10-m depth, 4.6 m in a 20-m depth, 5.5 m at a 30-m depth, and 6.8 m in a 40-m depth, when only an additional 0.5 m cable extension was used compared to the water depth. The GPS buoy requires good buoyancy in order to keep its position at the water surface when the diver is trying to minimize any additional cable extension error. The diver has to apply a tensile force for shortening the cable length at the lower cable end. Repeated diving along transect lines from 5 to 35 m resulted only in small deviations independent of water depth indicating the precision of the method for monitoring studies. Routing of given reference points with a Garmin 76CSx handheld placed in an underwater housing resulted in mean deviances less than 6 m at a water depth of 10 m. Thus, we can confirm that diver-towed GPS handhelds give promising results when used for underwater research in shallow water and open a wide field of applicability, but no submeter accuracy is possible due to the different error sources.     

The Paradox of E-Numbers: Ethical,Aesthetic, and Cultural Concerns in the Dutch Discourse on Food Additives

Persistent public distrust of food additives is often explained in terms of safety and health issues. The broad variety of ethical, aesthetic, and cultural concerns tends to be structurally ignored by food engineers and occasionally even by consumers themselves. The public controversy of food additives—commonly known as “E-numbers”—in the Netherlands is a case in point. Two discursive mechanisms prevent these concerns from becoming legitimate public issues: irrationalization and privatization. But these consumer concerns may not be as unreasonable as they seem, and they may even turn out to be not that private. As long as ethical, aesthetic and cultural concerns are not recognized by food engineers as legitimate issues, the controversy of food additives is not likely to find closure. Moreover, this lack of recognition blocks the opportunity for meaningful dialogue and trust building between food technology developers, policy makers, citizens and consumers.     

Improvement potential of today’s WEEE recycling performance: The case of LCD TVs in Belgium

Waste of electrical and electronic equipment (WEEE) constitutes one of the most relevant waste streams because of the quantity and presence of valuable materials. However, there is limited knowledge on the resource potential of urban mining WEEE, as data on material composition, and the efficiency of current recycling treatments are still scarce. In this article, an evaluation of the recycling performance at a national level for one of the fastest growing e-waste streams: LCD TVs is carried out through the following four steps. Firstly, material characterisation is performed by means of sampling of the waste stream. Secondly, a material flow analysis is conducted by evaluating the separation performance of a recycling plant in Belgium. Thirdly, the recovered economic value and avoided environmental impact (EI) of the analysed recycling system is assessed. Finally, the potential of urban mining for Belgium is forecasted. The analysis shows that while recycling performance for ferrous metals and aluminium are relatively high; there is substantial room to better close the material loops for precious metals (PM) and plastics. PMs and plastics account for 66 % of the economic value in LCD TVs and 57%of the EI.With the current, commonly applied recycling technology only one-third of the PM and housing plastics are recycled; meaning that for these materials, at a national level for Belgium, there is a potential for improvement that represents 3.3 million euros in 2016 and 6.8 million euros in 2025.

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An expanded conceptual framework for solution-focused management of chemical pollution in European waters

Background

This paper describes a conceptual framework for solutions-focused management of chemical contaminants built on novel and systematic approaches for identifying, quantifying and reducing risks of these substances.

Methods

The conceptual framework was developed in interaction with stakeholders representing relevant authorities and organisations responsible for managing environmental quality of water bodies. Stakeholder needs were compiled via a survey and dialogue. The content of the conceptual framework was thereafter developed with inputs from relevant scientific disciplines.

Results

The conceptual framework consists of four access points: Chemicals, Environment, Abatement and Society, representing different aspects and approaches to engaging in the issue of chemical contamination of surface waters. It widens the scope for assessment and management of chemicals in comparison to a traditional (mostly) perchemical risk assessment approaches by including abatement- and societal approaches as optional solutions. The solution-focused approach implies an identification of abatement- and policy options upfront in the risk assessment process. The conceptual framework was designed for use in current and future chemical pollution assessments for the aquatic environment, including the specific challenges encountered in prioritising individual chemicals and mixtures, and is applicable for the development of approaches for safe chemical management in a broader sense. The four access points of the conceptual framework are interlinked by four key topics representing the main scientific challenges that need to be addressed, i.e.: identifying and prioritising hazardous chemicals at different scales; selecting relevant and efficient abatement options; providing regulatory support for chemicals management; predicting and prioritising future chemical risks. The conceptual framework aligns current challenges in the safe production and use of chemicals. The current state of knowledge and implementation of these challenges is described.

Conclusions

The use of the conceptual framework, and addressing the challenges, is intended to support: (1) forwarding sustainable use of chemicals, (2) identification of pollutants of priority concern for cost-effective management, (3) the selection of optimal abatement options and (4) the development and use of optimised legal and policy instruments.

     

Microbially assisted phytoremediation approaches for two multi-element contaminated sites

Phytoremediation is an environmental friendly, cost-effective technology for a soft restoration of abandoned mine sites. The grasses Agrostis capillaris, Deschampsia flexuosa and Festuca rubra, and the annual herb Helianthus annuus were combined with microbial consortia in pot experiments on multi-metal polluted substrates collected at a former uranium mine near Ronneburg, Germany, and a historic copper mine in Kopparberg, Sweden, to test for phytoextraction versus phytostabilization abilities. Metal uptake into plant biomass was evaluated to identify optimal plant–microbe combinations for each substrate. Metal bioavailability was found to be plant species and element specific, and influenced by the applied bacterial consortia of 10 strains, each isolated from the same soil to which it was applied. H. annuus showed high extraction capacity for several metals on the German soil independent of inoculation. Our study could also show a significant enhancement of extraction for F. rubra and A. capillaris when combined with the bacterial consortium, although usually grasses are considered metal excluder species. On the Swedish mixed substrate, due to its toxicity, with 30 % bark compost, A. capillaris inoculated with the respective consortium was able to extract multi-metal contaminants.     

Pteris vittata – Revisited: Uptake of As and its speciation, impact of P, role of phytochelatins and S

Pteris vittata is known to hyperaccumulate As but the mechanism is poorly understood. We found an increase of As concentration with increasing soil solution As concentrations, but P application had no impact, although plant P concentrations responded to different rates of P supply. As in fronds was dominantly (82–89%) present in the form of AsIII. In roots we detected 45% as AsIII which is higher than reported in previous studies and supports substantial As-reduction to take place in roots. We detected PC2/3GS–AsIII, PC2–GS–AsIII and (PC2)2–AsIII in increasing amounts with application of As. The total amount of PC was in the range reported previously and far too small to assign a significant role in As detoxification to PCs. The close correlation between S and As in fronds and the lack of data on sulphur uptake and metabolism indicates the need for a detailed investigation on sulphur nutritional status and As metabolism in P. vittata.     

Characterization of colloidal arsenic at two abandoned gold mine sites in Nova Scotia, Canada, using asymmetric flow-field flow fractionation-inductively coupled plasma mass spectrometry

Asymmetric flow-field flow fractionation-inductively-coupled plasma-mass spectrometry was used to determine whether colloidal arsenic(As) exists in soil pore water and soil extract samples at two arsenic-contaminated abandoned gold mines(Montague and Goldenville, Nova Scotia). Colloidal arsenic was found in 12 out of the 80 collected samples(= 15%), and was primarily associated with iron(Fe) in the encountered colloids. The molar Fe/As ratios indicate that the colloids in some samples appeared to be discrete iron–arsenic minerals, whereas in other samples, they were more consistent with As-rich iron(oxy)hydroxides. Up to three discrete size fractions of colloidal As were encountered in the samples, with mean colloid diameters between 6 and 14 nm. The pore water samples only contained one size fraction of As-bearing colloids(around 6 nm diameter), while larger As-bearing colloids were only encountered in soil extracts.