Sediment water (interface) mobility of metal(loid)s and nutrients under undisturbed conditions and during resuspension.

The contribution of the release from sediments to the overall river Trave budget was evaluated with respect to 16 metal(loid)s, three non-metals and the ions PO43- and NH4+. To consider undisturbed conditions and sediment resuspension in-situ dialyses-based and ex-situ suction-based pore water sampling was complemented by sequential extraction and suspension reactor experiments. In the investigated sediments, representative for the study area, metal(loid) partitioning between the different geochemical fractions was very similar despite some higher contaminated spots. Pore water investigations emphasis that profiling and peeper based analyses are comparable and deliver an indication that sediment dwelling organisms are exposed to elevated metal(loid) concentrations. However, higher toxicity of the contaminated sediments compared to the sediment treated as background reference was not revealed. During resuspension only few metal(loid)s exceeded specified guideline values. The maximum amounts released, were only between 10-5 and 10-1% of the average daily load of the river Trave per ton of suspended sediment. Overall the "most pristine sediments" and not the potentially hazardous materials in the study area are found to be from highest concern. The results support requests to better include fractionation and speciation demands in legal assessments of sediments.

Cyanobacterial promoted enrichment of rare earth elements europium, samarium and neodymium and intracellular europium particle formation.

In the recovery of rare earth elements (REE) microbial biosorption has shown its theoretical ability as an extremely economically and environmentally friendly production method in the last few years. To evaluate the ability of two cyanobacterial strains, namely Anabaena spec. and Anabaena cylindrica to enrich dissolved trivalent REE, a simple protocol was followed. The REE tested in this study include some of the most prominent representatives, such as europium (Eu), samarium (Sm) and neodymium (Nd). Within the experiments, a fast decrease of the REE3+ concentration in solution was tracked by inductively coupled plasma mass spectrometry (ICP-MS). It revealed an almost complete (>99%) biosorption of REE3+ within the first hour after the addition of metal salts. REE3+ uptake by biomass was checked using laser-induced breakdown spectroscopy (LIBS) and showed that all three selected REE3+ species were enriched in the cyanobacterial biomass and the process is assigned to a biosorption process. Although the biomass stayed alive during the experiments, up to that, a distinction whether the REE3+ was intra- or extracellularly sorbed was not possible, since biosorption is a metabolism independent process which occurs on living as well as non-living biomass. For europium it was shown by TEM that electron dense particles, presumably europium particles with particle sizes of about 15 nm, are located inside the vegetative cyanobacterial cells. This gave clear evidence that Eu3+ was actively sorbed by living cyanobacteria. Eu3+ biosorption by cell wall precipitation due to interaction with extracellular polysaccharides (EPS) could therefore be excluded. Finally, with XRD analysis it was shown that the detected europium particles had an amorphous instead of a crystalline structure. Herein, we present a fast biosorptive enrichment of the rare earth elements europium, samarium and neodymium by Anabaena spec. and Anabaena cylindrica and for the first time the subsequent formation of intracellular europium particles by Anabaena spec.

Impact of mechanical disturbance and acidification on the metal(loid) and C, P, S mobility at the sediment water interface examined using a fractionation meso profiling ICP-QQQ-MS approach.

The impact of mechanical disturbance and oxygen induced acidification on the concentration and size fractionation of the 12 metal(loid)s As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Tl, V and the polyatomic nonmetals C, P and S in the pore water was studied. Using the meso profiling and sampling system (messy) 12 pore water depth profiles were sampled from two incubation experiments undertaken in parallel, which were both mechanically disturbed in the lab and subsequently exposed to a different air supply. In parallel to the low invasive, automated sampling process the redox potential, the pH value and the O2 concentration were detected. Simultaneous quantification of all analytes by inductively coupled plasma-triple quad-mass spectrometry in the two different size classes dissolved (<0.45 µm) and colloidal (0.45-16 µm) showed: i) the predominant influence of the pH on the mobility of metals; ii) the mobility of metalloids was strongly impacted by the mechanical disturbance; and iii) the colloidal release is less important except for Fe, P, and Ni.

Metal(loid) speciation and size fractionation in sediment pore water depth profiles examined with a new meso profiling system.

In an exemplary incubation study with an anaerobic sediment sampled at an oxbow of the river Lahn in Germany (50°18'56.87″N; 7°37'41.25″E) and contaminated by former mining activity, a novel meso profiling and sampling system (messy) is presented. Messy enables a low invasive, automated sampling of pore water profiles across the sediment water interface (SWI), down to ∼20 cm depth with a spacial resolution of 1 cm. In parallel to the pore water sampling it measures physicochemical sediment parameters such as redox potential and pH value. In an incubation experiment of 151 days the ability of the setup was proven to address several different aspects relevant for fresh water and marine sediment studies: (i) The influence of mechanical disturbance and oxygen induced acidification on the mobility of 13 metals and metalloids (Cd, Co, Cu, Fe, Mn, Mo, Ni, Sb, U, V, Zn) was quantified based on 11 profiles. The analytes were quantified by inductively coupled plasma-mass spectrometry. Three groups of elements were identified with respect to the release into the pore water and the overlying water under different experimental conditions. (ii) The capability to investigate the impacts of changing physicochemical sediment properties on arsenic and antimony (III/V) speciation is shown. (iii) An approach to obtain information on size fractionation effects and to address the colloidal pore water fractions (0.45 µm-16 µm) was successfully conducted for the elements Ag, As, Cu, Fe and Mn.

A Framework to Evaluate the Impact of Armourstones on the Chemical Quality of Surface Water.

Today, basic requirements for construction works include the protection of human health and of the environment. In the tension area between economic demands, circular flow economy and environmental safety, a link between the results from standardized leaching tests and the respective environmental quality standards must be created. To derive maximum release limits of metals and metalloids for armourstones in hydraulic engineering, this link is accomplished via a simple model approach. By treating natural materials and industrial by-products the same way, the article delivers an overview on the recent regulative situation in Europe as well as describes and discusses an innovative approach to derive maximum release limits for monolithic construction products in hydraulic engineering on a conceptual level. On a practical level, a list of test parameters is derived by connecting an extensive dataset (seven armourstone materials with five repetitions and 31 elements tested with the worldwide applied dynamic surface leaching test) with surface water quality standards and predicted no effect concentrations. Finally, the leaching tests results are compared with the envisaged maximum release limits, offering a direct comparison between natural materials and industrial by-products.

Metal and Metalloid Size-Fractionation Strategies in Spatial High-Resolution Sediment Pore Water Profiles.

Sediment water interfaces (SWIs) are often characterized by steep biogeochemical gradients determining the fate of inorganic and organic substances. Important transport processes at the SWI are sedimentation and resuspension of particulate matter and fluxes of dissolved materials. A microprofiling and micro sampling system (missy), enabling high resolution measurements of sediment parameters in parallel to a direct sampling of sediment pore waters (SPWs), was combined with two fractionation approaches (ultrafiltration (UF) and cloud point extraction (CPE)) to differentiate between colloidal and dissolved fractions at a millimeter scale. An inductively coupled plasma-quadrupole mass spectrometry method established for volumes of 300 µL enabled the combination of the high resolution fractionation with multi-element analyzes. UF and CPE comparably indicated that manganese is predominantly present in dissolved fractions of SPW profiles. Differences found for cobalt and iron showed that the results obtained by size-dependent UF and micelle-mediated CPE do not necessarily coincide, probably due to different fractionation mechanisms. Both methods were identified as suitable for investigating fraction-related element concentrations in SPW along sediment depth profiles at a millimeter scale. The two approaches are discussed with regard to their advantages, limitations, potential sources of errors, further improvements, and potential future applications.

New microprofiling and micro sampling system for water saturated environmental boundary layers.

The spatial high resolution of a microprofiling system was combined with the multi element capability of ICP-MS to enable a better understanding of element distributions and related processes across environmental boundary layers. A combination of a microprofiling system with a new micro filtration probe head connected to a pump and a fraction collector (microprofiling and micro sampling system, missy) is presented. This enables for the first time a direct, dynamic, and high resolution automatic sampling of small water volumes (<500 µL) from depth profiles of water saturated matrices (e.g., sediments, soils, biofilms). Different membrane cut-offs are available, and resolutions of a few (matrices with a high physical resistance) to a submillimeter scale (matrices with low physical resistance) can be achieved. In this Article, (i) the modular setups of two missys are presented; (ii) it is demonstrated how the micro probe heads are manufactured; (iii) background concentrations and recoveries of the system as well as (iv) exemplary results of a sediment water interface are delivered. On the basis of this, potentials, possible sources of errors, and future applications of the new missy are discussed.