Unravelling phosphate adsorption on hydrous ferric oxide surfaces at the molecular level.

The thorough understanding of the adsorption mechanism of phosphate on hydrous ferric oxides is necessary to deal with the environmental issues related to high phosphate concentrations in soils and open water. In this work, we consider three different adsorption geometries (monodentate and bidentate chemisorption and physisorption) and calculate the adsorption geometries and related adsorption energies at optPBE-vdW level. Using the Maxwell-Boltzmann distribution, it is estimated that about 83% of the phosphate molecules is in a monodentate chemisorption configuration, while 17% is physisorbed.

Influence of seawater ions on phosphate adsorption at the surface of hydrous ferric oxide (HFO).

The adsorption of phosphate on hydrated ferric oxide (HFO) was studied in solutions containing major seawater ions (Na, Mg, Cl, SO, Ca, K) at pHs 6.5, 7.5 and 8.

Nutrient, pigment, suspended matter and turbidity measurements in the Belgian part of the North Sea.

Through regular sampling surveys, the Flanders Marine Institute is generating long term data series for the Belgian coastal water and sand bank systems, a designated site in the Long Term Ecological Research (LTER) network. The data series is built on sampling activities initiated in 2002, but gradually upgraded and extended in the framework of the LifeWatch marine observatory and the Integrated Carbon Observation System (ICOS) participation. Nine nearshore stations are sampled monthly, with additional seasonal sampling of eight offshore stations.

Phosphate adsorption on hydrous ferric oxide (HFO) at different salinities and pHs.

Phosphate adsorption on suspended sediments is largely influenced by the variations in salinity and pH such as is the case in estuaries where freshwater mixes with seawater, exhibiting strong physico-chemical gradients. In this research, the influence of salinity and pH on the adsorption of phosphate on hydrous ferric oxides (HFO) was investigated in NaCl solutions. The adsorption isotherm data at different salinities can be well fitted with the Langmuir-Freundlich model.

Biological responses of the marine diatom Chaetoceros socialis to changing environmental conditions: A laboratory experiment.

Diatoms constitute a major group of phytoplankton, accounting for ~20% of the world's primary production. It has been shown that iron (Fe) can be the limiting factor for phytoplankton growth, in particular, in the HNLC (High Nutrient Low Chlorophyll) regions. Iron plays thus an essential role in governing the marine primary productivity and the efficiency of biological carbon pump.

Hydrodynamic influence on reservoir sustainability in semi-arid climate: A physicochemical and environmental isotopic study.

Water scarcity and increasing water demand require the development of water management plans such as establishing artificial lakes and dams. Plans to meet water needs are faced by uprising challenges to improve water quality and to ensure the sustainability of hydro-projects. Environmental isotopes coupled to water physicochemical characteristics were investigated over a biennial cycle to assess both geomorphological and environmental impacts on the water quality of a reservoir situated in an intensively used agricultural watershed under a Mediterranean semi-arid climate.

Role of phosphogypsum and NPK amendments on the retention or leaching of metals in different soils.

Column leaching tests were conducted to investigate the effects of soil physicochemical characteristics on metal mobility in the subsurface. The metals investigated originated from disposed industrial waste byproducts and from agrochemicals spread over the farmlands. Soil column tests can provide insights into leaching of metals to underlying water compartments.

Reservoir sediments: a sink or source of chemicals at the surface water-groundwater interface.

This study delineates the physical, chemical, and biological effects resulting from anthropogenic and endogenic activities in a sensitive dammed reservoir situated in a semi-arid region. The reservoir is characterized by two major flow regimes: a wet fill hydrologic regime and a dry spill one. A seasonal sampling campaign was carried out over a period of 2 years (2011-2013) where water samples were collected across the water column and from piezometers just outside the perimeter of the reservoir.

Modelling metal speciation in the Scheldt Estuary: combining a flexible-resolution transport model with empirical functions.

Predicting metal concentrations in surface waters is an important step in the understanding and ultimately the assessment of the ecological risk associated with metal contamination. In terms of risk an essential piece of information is the accurate knowledge of the partitioning of the metals between the dissolved and particulate phases, as the former species are generally regarded as the most bioavailable and thus harmful form. As a first step towards the understanding and prediction of metal speciation in the Scheldt Estuary (Belgium, the Netherlands), we carried out a detailed analysis of a historical dataset covering the period 1982-2011.

Applying physicochemical approaches to control phosphogypsum heavy metal releases in aquatic environment.

One of the most important sources of solid waste in the Mediterranean Basin ecosystem originated from the phosphate fertilizer industries, which discharge phosphogypsum (PG) directly into aquatic environments or are stacked on stockpiles. The present study investigates metal release from PG under the influence of variable pH, increasing PG mass content, and complexing organic matter ligands. Major ions from PG leachates, grain size and charge, main functional groups along with metal leachability (Pb, Cd, Cr, Cu, and Zn) were determined using ion chromatography, laser diffraction, zetameter, Fourier transform infrared spectroscopy, and atomic absorption spectroscopy, respectively.

Precise measurement of Fe isotopes in marine samples by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS).

A novel analytical technique for isotopic analysis of dissolved and particulate iron (Fe) from various marine environments is presented in this paper. It combines coprecipitation of dissolved Fe (DFe) samples with Mg(OH)(2), and acid digestion of particulate Fe (PFe) samples with double pass chromatographic separation. Isotopic data were obtained using a Nu Plasma MC-ICP-MS in dry plasma mode, applying a combination of standard-sample bracketing and external normalization by Cu doping.