The Zoning of Semi-Enclosed Bodies of Water According to the Sediment Pollution: The Bay of Algeciras as a Case Example

This paper reports a study of the occurrence and levels of polycyclic aromatic hydrocarbons (PAHs) in a bay characterised by a chronic persistent impact. A total of 55 sediment samples were taken at different depths up to 111 m in two sampling campaigns. Chemical analyses were carried out by gas chromatography-mass spectroscopy. The results indicate that: (1) significant spatial variations exist, (2) levels of PAHs are related more strongly to the spatial distribution of sediments than to mineralogy/granulometry, (3) the sediments are slightly-to-moderately contaminated by PAHs, and (4) these PAHs derive from pyrolytic and petrogenic sources. Through use of an innovative data classification system (proposed according to depth and spatial location of sampling points), and using factorial and cluster techniques, five zones have been differentiated depending on the contamination level and source

High-field FT-ICR mass spectrometry and NMR spectroscopy to characterize DOM removal through a nanofiltration pilot plant.

Ultrahigh resolution Fourier transform ion cyclotron mass spectrometry and nuclear magnetic resonance spectroscopy were combined to evaluate the molecular changes of dissolved organic matter (DOM) through an ultrafiltration-nanofiltration (UF-NF) pilot plant, using two dissimilar NF membranes tested in parallel. The sampling was performed on seven key locations within the pilot plant: pretreated water, UF effluent, UF effluent after addition of reagents, permeate NF 1, permeate NF 2, brine NF 1 and brine NF 2, during two sampling campaigns. The study showed that there is no significant change in the nature of DOM at molecular level, when the water was treated with UF and/or with the addition of sodium metabisulfite and antiscaling agents. However, enormous decrease of DOM concentration was observed when the water was treated on the NF membranes. The NF process preferentially removed compounds with higher oxygen and nitrogen content (more hydrophilic compounds), whereas molecules with longer pure aliphatic chains and less content of oxygen were the ones capable of passing through the membranes. Moreover, slight molecular selectivity between the two NF membranes was also observed

Sorption of antimony (V) onto synthetic goethite in carbonate medium

The sorption kinetics of antimony(V) on synthetic goethite is very fast compared to the sorption of other metals on goethite (e.g. arsenic and selenium) and depends on temperature, with an activation energy of 49+9 kJ . mol21 in the temperature range 15–358C. Sorption isotherms have been developed at different temperatures and ionic strength values. The results have been modelled using a Langmuir isotherm and there is not a considerable influence of neither the temperature in the range studied (158C–358C), nor the ionic strength (between 0.001 and 0.01 mol . dm23). Sorption is very high at pH values lower than 8, at more alkaline pH, the sorption decreases with pH, as expected considering the Antimony(V) predominating complex in solution, Sb(OH)6 2. Triple-layer model successfully describes the data obtained by assuming a bidentate edge-sharing surface complex of antimonate on the surface of goethite.Peer ReviewedPostprint (published version

Sorption of antimony (V) onto synthetic goethite in carbonate medium

The sorption kinetics of antimony(V) on synthetic goethite is very fast compared to the sorption of other metals on goethite (e.g. arsenic and selenium) and depends on temperature, with an activation energy of 49+9 kJ . mol21 in the temperature range 15–358C. Sorption isotherms have been developed at different temperatures and ionic strength values. The results have been modelled using a Langmuir isotherm and there is not a considerable influence of neither the temperature in the range studied (158C–358C), nor the ionic strength (between 0.001 and 0.01 mol . dm23). Sorption is very high at pH values lower than 8, at more alkaline pH, the sorption decreases with pH, as expected considering the Antimony(V) predominating complex in solution, Sb(OH)6 2. Triple-layer model successfully describes the data obtained by assuming a bidentate edge-sharing surface complex of antimonate on the surface of goethite.Peer Reviewe

Effects of Reclaimed Water and C and N on Breakthrough Curves in Sandy Soil and Loam

International audienceLong-term irrigation with reclaimed water may change soil physical properties and solute transport rate due to C and N in reclaimed water and the particularity of reclaimed water. Ordinary water, reclaimed water and mixed water which added C and N into reclaimed water were used as background water, then potassium bromide was added to background water and mixed them into three kinds of solutions whose bromide concentrations were all 0.5 mol/L, then soil column breakthrough experiments were conducted. The results showed that bacteria quantity increased both in sandy soil and loam after soil column experiments, and bacteria quantity in sandy soil and loam were all in the following descending order: breakthrough solution using mixed water as background water, breakthrough solution using reclaimed water as background water, and breakthrough solution using ordinary water as background water. However, fungi quantity had no significant difference. Cumulative infiltration in sandy soil and loam can be properly described by power function and logarithm function, respectively. The amount of cumulative infiltration in sandy soil and loam in the same infiltration time were all showed a descending order as: breakthrough solution using ordinary water as background water, breakthrough solution using reclaimed water as background water, and breakthrough solution using mixed water as background water. Breakthrough curves can be well described by CXTFIT 2.1 code, it can be seen from the values of V and D that reclaimed water and the addition of C and N made solute transport more difficult in soils and increased diffusion coefficient, and these impacts were greater on loam than sandy soil. Reclaimed water and the added C and N increased soil bacteria, complicated soil pore system, and decreased soil hydraulic conductivity