Combining sequential extractions with bulk and micro X-ray spectroscopy to elucidate iron and phosphorus speciation in sediments of an iron-treated peat lake.

In shallow lakes, mobilization of legacy phosphorus (P) from the sediments can be the main cause for persisting eutrophication after reduction of external P input. In-lake remediation measures can be applied to reduce internal P loading and to achieve ecosystem recovery. The eutrophic shallow peat lake Terra Nova (The Netherlands) was treated with iron (Fe) to enhance P retention in the sediment.

Impact of iron addition on phosphorus dynamics in sediments of a shallow peat lake 10 years after treatment.

Internal phosphorus (P) loading is a key water quality challenge for shallow lakes. Addition of iron (Fe) salts has been used to enhance P retention in lake sediments. However, its effects on sediment geochemistry are poorly studied, albeit pivotal for remediation success.

Transport-limited kinetics of phosphate retention on iron-coated sand and practical implications.

Iron-coated sand (ICS) is a by-product from drinking water treatment made of sand coated with ferric iron (hydr)oxides. It is considered a suitable material for large-scale measures for phosphate removal from natural and agricultural waters to prevent eutrophication. Previous studies demonstrated that the residence time of water must be very long to reach equilibrium partitioning between phosphate and ICS but specifics for application are missing.

Phosphorus adsorption on iron-coated sand under reducing conditions.

Mitigation measures are needed to prevent large loads of phosphate originating in agriculture from reaching surface waters. Iron-coated sand (ICS) is a residual product from drinking water production. It has a high phosphate adsorption capacity and can be placed around tile drains, taking no extra space, which increases the farmers' acceptance.

Coupled dynamics of iron, manganese, and phosphorus in brackish coastal sediments populated by cable bacteria.

Coastal waters worldwide suffer from increased eutrophication and seasonal bottom water hypoxia. Here, we assess the dynamics of iron (Fe), manganese (Mn), and phosphorus (P) in sediments of the eutrophic, brackish Gulf of Finland populated by cable bacteria. At sites where bottom waters are oxic in spring, surface enrichments of Fe and Mn oxides and high abundances of cable bacteria were observed in sediments upon sampling in early summer.

Coprecipitation of Phosphate and Silicate Affects Environmental Iron (Oxyhydr)Oxide Transformations: A Gel-Based Diffusive Sampler Approach.

Sorption of nutrients such as phosphate (P) and silicate (Si) by ferric iron (oxyhydr)oxides (FeOx) modulates nutrient mobility and alters the structure and reactivity of the FeOx. We investigated the impact of these interactions on FeOx transformations using a novel approach with samplers containing synthetic FeOx embedded in diffusive hydrogels. The FeOx were prepared by Fe(III) hydrolysis and Fe(II) oxidation, in the absence and presence of P or Si.

Sorption of phosphate and silicate alters dissolution kinetics of poorly crystalline iron (oxyhydr)oxide.

Iron (oxyhydr)oxides (FeOx) control retention of dissolved nutrients and contaminants in aquatic systems. However, FeOx structure and reactivity is dependent on adsorption and incorporation of such dissolved species, particularly oxyanions such as phosphate and silicate. These interactions affect the fate of nutrients and metal(loids), especially in perturbed aquatic environments such as eutrophic coastal systems and environments impacted by acid mine drainage.

Sustaining efficient production of aqueous iron during repeated operation of Fe(0)-electrocoagulation.

Iron-electrocoagulation is a promising contaminant (e.g. arsenic) removal technology that is based on electrochemical Fe(II) production from steel electrodes and subsequent transport of Fe(II) to the bulk solution, where contaminant removal occurs.

Fate of Adsorbed U(VI) during Sulfidization of Lepidocrocite and Hematite.

The impact on U(VI) adsorbed to lepidocrocite (γ-FeOOH) and hematite (α-FeO) was assessed when exposed to aqueous sulfide (S(-II)) at pH 8.0. With both minerals, competition between S(-II) and U(VI) for surface sites caused instantaneous release of adsorbed U(VI).

Bacteriophage PRD1 batch experiments to study attachment, detachment and inactivation processes.

Knowledge of virus removal in subsurface environments is pivotal for assessing the risk of viral contamination of water resources and developing appropriate protection measures. Columns packed with sand are frequently used to quantify attachment, detachment and inactivation rates of viruses. Since column transport experiments are very laborious, a common alternative is to perform batch experiments where usually one or two measurements are done assuming equilibrium is reached.

Effect of dissolved calcium on the removal of bacteriophage PRD1 during soil passage: the role of double-layer interactions.

The objective of this work was to investigate and obtain quantitative relations for the effects of Ca(2+) concentration on virus removal in saturated soil and to compare the experimental findings with predictions of the DLVO theory. In order to do so, a systematic study was performed with a range of calcium concentrations corresponding to natural field conditions. Experiments were conducted in a 50-cm column with clean quartz sand under saturated conditions.

Distribution and diversity of Gallionella-like neutrophilic iron oxidizers in a tidal freshwater marsh.

Microbial iron oxidation is an integral part of the iron redox cycle in wetlands. Nonetheless, relatively little is known about the composition and ecology of iron-oxidizing communities in the soils and sediments of wetlands. In this study, sediment cores were collected across a freshwater tidal marsh in order to characterize the iron-oxidizing bacteria (FeOB) and to link their distributions to the geochemical properties of the sediments.

Systematic study of effects of pH and ionic strength on attachment of phage PRD1.

Objectives of this work are to investigate effects of pH and ionic strength (IS) on virus transport in saturated soil and to develop a quantitative relationship for these effects. A series of 50-cm column experiments with clean quartz sand under saturated conditions and with pH values of 5, 6, 7, 8, and IS values of 1, 10, and 20 mM were conducted. Bacteriophage PRD1 was used as a model virus.

Effect of sediment properties on the sorption of C12-2-LAS in marine and estuarine sediments.

Linear alkylbenzene sulfonates (LAS) are anionic high production volume surfactants used in the manufacture of cleaning products. Here, we have studied the effect of the characteristics of marine and estuarine sediments on the sorption of LAS. Sorption experiments were performed with single sediment materials (pure clays and sea sand), with sediments treated to reduce their organic carbon content, and with field marine and estuarine sediments.

Biosorption of metals (Cu(2+), Zn(2+)) and anions (F(-), H(2)PO(4)(-)) by viable and autoclaved cells of the Gram-negative bacterium Shewanella putrefaciens.

Microbial biomass represents a potentially cost-effective sorbent for water treatment applications. High sorption capacities for both cations and anions are demonstrated here for viable and autoclaved cell suspensions of the Gram-negative bacterium Shewanella putrefaciens. FTIR absorption spectra and pH-dependent zeta-potentials are similar for the viable and killed bacterial cells.