References of "Water Research"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailMulti-species measurements of nitrogen isotopic composition r 1 eveal the spatial constraints and 2 biological drivers of ammonium attenuation across a highly contaminated groundwater system
Wells, Naomi S.; Hakoun, Vivien ULg; Brouyère, Serge ULg et al

in Water Research (2016), 98

Groundwater under industrial sites is characterised by heterogeneous chemical mixtures, making it difficult to assess the fate and transport of individual contaminants. Quantifying the in-situ biological ... [more ▼]

Groundwater under industrial sites is characterised by heterogeneous chemical mixtures, making it difficult to assess the fate and transport of individual contaminants. Quantifying the in-situ biological removal (attenuation) of nitrogen (N) is particularly difficult due to its reactivity and ubiquity. Here a multi-isotope approach is developed to distinguish N sources and sinks within groundwater affected by complex industrial pollution. Samples were collected from 70 wells across the two aquifers underlying a historic industrial area in Belgium. Below the industrial site the groundwater contained up to 1000 mg Nl-1 ammonium (NH4 +) and 300 mg N l-1 nitrate (NO3-), while downgradient concentrations decreased to ~1 mg l-1 DIN ([DIN] = [NH4+-N] + [NO3--N] + [NO2--N]). Mean δ1534 N-DIN increased from ~2‰ to +20‰ over this flow path, broadly confirming that biological N attenuation drove the measured concentration decrease. Multi-variate analysis of water chemistry identified two distinct NH4+ sources (δ15N-NH4+ from -14‰ and +5‰) within the contaminated zone of both aquifers. Nitrate dual isotopes co-varied (δ15 N: -3‰ - +60‰; δ18O: 0‰ - +50‰) within the range expected for coupled nitrification and denitrification of the identified sources. The fact that δ15N-NO2- values were 50‰ to 20‰ less than δ15N-NH4+ values in 40 the majority of wells confirmed that nitrification controlled N turnover across the site. However, the fact that δ15N-NO2- was greater than δ15N-NH4+ in wells with the highest [NH4+] shows that an autotrophic NO2- reduction pathway (anaerobic NH4+ oxidation or nitrifier-denitrification) drove N attenuation closest to the contaminant plume. This direct empirical evidence that both autotrophic and heterotrophic biogeochemical processes drive N attenuation in contaminated aquifers demonstrates the power of multiple N isotopes to untangle N cycling in highly complex systems. [less ▲]

Detailed reference viewed: 17 (4 ULg)
Full Text
Peer Reviewed
See detailUse of dual carbon-chlorine isotope analysis to assess the degradation pathways of 1,1,1-trichloroethane in groundwater
Palau, Jordi; Jamin, Pierre ULg; Badin, Alice et al

in Water Research (2016)

Compound-specific isotope analysis (CSIA) is a powerful tool to track contaminant fate in groundwater. However, the application of CSIA to chlorinated ethanes has received little attention so far. These ... [more ▼]

Compound-specific isotope analysis (CSIA) is a powerful tool to track contaminant fate in groundwater. However, the application of CSIA to chlorinated ethanes has received little attention so far. These compounds are toxic and prevalent groundwater contaminants of environmental concern. The high susceptibility of chlorinated ethanes like 1,1,1-trichloroethane (1,1,1-TCA) to be transformed via different competing pathways (biotic and abiotic) complicates the assessment of their fate in the subsurface. In this study, the use of a dual C-Cl isotope approach to identify the active degradation pathways of 1,1,1-TCA is evaluated for the first time in an aerobic aquifer impacted by 1,1,1-TCA and trichloroethylene (TCE) with concentrations of up to 20 mg/L and 3.4 mg/L, respectively. The reaction-specific dual carbon-chlorine (C-Cl) isotope trends determined in a recent laboratory study illustrated the potential of a dual isotope approach to identify contaminant degradation pathways of 1,1,1-TCA. Compared to the dual isotope slopes (Δδ13C/Δδ37Cl) previously determined in the laboratory for dehydrohalogenation / hydrolysis (DH/HY, 0.33 ± 0.04) and oxidation by persulfate (∞), the slope determined from field samples (0.6 ± 0.2, r2 = 0.75) is closer to the one observed for DH/HY, pointing to DH/HY as the predominant degradation pathway of 1,1,1-TCA in the aquifer. The observed deviation could be explained by a minor contribution of additional degradation processes. This result, along with the little degradation of TCE determined from isotope measurements, confirmed that 1,1,1-TCA is the main source of the 1,1-dichlorethylene (1,1-DCE) detected in the aquifer with concentrations of up to 10 mg/L. This study demonstrates that a dual C-Cl isotope approach can strongly improve the qualitative and quantitative assessment of 1,1,1-TCA degradation processes in the field. [less ▲]

Detailed reference viewed: 39 (7 ULg)
Full Text
Peer Reviewed
See detailTreatment of estrogens and androgens in dairy wastewater by a constructed wetland system.
Cai, Kai; Elliott, Christopher T; Phillips, Debra H et al

in Water Research (2012), 46(7), 2333-43

Constructed wetland systems (CWS) have been used as a low cost bio-filtration system to treat farm wastewater. While studies have shown that CWS are efficient in removing organic compounds and pathogens ... [more ▼]

Constructed wetland systems (CWS) have been used as a low cost bio-filtration system to treat farm wastewater. While studies have shown that CWS are efficient in removing organic compounds and pathogens, there is limited data on the presence of hormones in this type of treatment system. The objective of this study was to evaluate the ability of the CWS to reduce estrogenic and androgenic hormone concentration in dairy wastewater. This was achieved through a year long study on dairy wastewater samples obtained from a surface flow CWS. Analysis of hormonal levels was performed using a solid phase extraction (SPE) sample clean-up method, combined with reporter gene assays (RGAs) which incorporate relevant receptors capable of measuring total estrogenic or androgenic concentrations as low as 0.24 ng L(-1) and 6.9 ng L(-1) respectively. Monthly analysis showed a mean removal efficiency for estrogens of 95.2%, corresponding to an average residual concentration of 3.2 ng L(-1) 17beta-estradiol equivalent (EEQ), below the proposed lowest observable effect concentration (LOEC) of 10 ng L(-1). However, for one month a peak EEQ concentration of 115 ng L(-1) was only reduced to 18.8 ng L(-1). The mean androgenic activity peaked at 360 ng L(-1) and a removal efficiency of 92.1% left an average residual concentration of 32.3 ng L(-1) testosterone equivalent (TEQ). The results obtained demonstrate that this type of CWS is an efficient system for the treatment of hormones in dairy wastewater. However, additional design improvements may be required to further enhance removal efficiency of peak hormone concentrations. [less ▲]

Detailed reference viewed: 69 (15 ULg)
Full Text
Peer Reviewed
See detailInfluence of Back Mixing on the Convective Drying of Residual Sludges in a Fixed Bed
Léonard, Angélique ULg; Meneses, Eustedio; Le Trong, Emmanuel et al

in Water Research (2008), 42(10-11), 2671-2677

The influence of a backmixing operation on the convective belt drying of two wastewater sludges was studied. The expansion of the sludge extrudates bed due to increasing additions of dry product was ... [more ▼]

The influence of a backmixing operation on the convective belt drying of two wastewater sludges was studied. The expansion of the sludge extrudates bed due to increasing additions of dry product was quantified by using X-ray tomography. This non-invasive technique was used to determine the bed porosity and the total exchange area available for heat and mass transfers, for increasing levels of backmixing. For a same drying flux, the expansion of the drying bed leads to higher drying rates, allowing a reduction of the total drying time. In this context, rheological properties of the sludges are key properties. [less ▲]

Detailed reference viewed: 51 (8 ULg)
Full Text
Peer Reviewed
See detailNew Model For Performance Prediction In Fixed-Bed Reactors Based On The Approach Of The Unused Bed Zone
Fanfan, Pierre Naïder; Mabon, Nicolas; Carletti, Isabelle et al

in Water Research (2005), 39(16), 4004-4010

Detailed reference viewed: 79 (2 ULg)
Full Text
Peer Reviewed
See detailPotamon: A Dynamic Model for Predicting Phytoplankton Composition and Biomass in Lowland Rivers
Everbecq, Etienne ULg; Gosselain, Véronique ULg; Viroux, Laurent et al

in Water Research (2001), 35(4), 901-12

POTAMON is a unidimensional, non-stationary model, designed for simulating potamoplankton from source to mouth. The forcing variables are discharge, river morphology, water temperature, available light ... [more ▼]

POTAMON is a unidimensional, non-stationary model, designed for simulating potamoplankton from source to mouth. The forcing variables are discharge, river morphology, water temperature, available light and nutrient inputs. Given the description of several algal categories, POTAMON allows to simulate algal "successions" at a particular site, as well as longitudinal changes of potamoplankton composition and biomass. The algal categories differ by their physiology, their loss rates, and their sensitivity to grazing by zooplankton. Two zooplankton categories were considered, Brachionus-like and Keratella-like, which differ by their clearance rate, their incipient limiting level, their selectivity towards phytoplankton, and their growth yield. The model simulates satisfactorily the onset and the magnitude of the phytoplankton spring bloom in the Belgian part of R. Meuse, the biomass decrease in early summer, and the autumn bloom. It also renders the major variations of algal assemblages along the river. The model allows to confirm that the main driving variables of potamoplankton dynamics in a eutrophic river are physical factors: discharge and related variables (e.g. retention time), light and temperature. In addition, the simulations confirm that the zooplankton-phytoplankton interaction may result in phytoplankton biomass fluctuations and compositional changes. POTAMON can be useful to explore plankton dynamics in a large river, and it may become a tool to test various management measures. [less ▲]

Detailed reference viewed: 49 (8 ULg)
Full Text
Peer Reviewed
See detailA New Design of Equilibrator to Monitor Carbon Dioxide in Highly Dynamic and Turbid Environments
Frankignoulle, M.; Borges, Alberto ULg; Biondo, Renzo ULg

in Water Research (2001), 35(5), 1344-7

A new design of equilibrator for carbon dioxide monitoring in natural waters is described. It consists in a vertical tube filled with marbles through which water is flowing while equilibrating with a ... [more ▼]

A new design of equilibrator for carbon dioxide monitoring in natural waters is described. It consists in a vertical tube filled with marbles through which water is flowing while equilibrating with a closed air circuit. It offers several advantages compared with classical equilibrators, among which is a fast response time (half-life constant approximately 30 s) and the potential to work in very turbid water. The proposed equilibrator is of particular interest to monitor carbon dioxide in coastal ecosystems, such as estuaries, which are known to be turbid and highly dynamic. Two performance tests and some field results are presented to illustrate the efficiency of the proposed system. [less ▲]

Detailed reference viewed: 34 (5 ULg)
Peer Reviewed
See detailComment on "Stratification dynamics in wastewater stabilization ponds", by R. Gu and H.G. Stefan
Djenidi, Salim ULg

in Water Research (1998), 32(1), 261-262

Detailed reference viewed: 16 (4 ULg)
Full Text
Peer Reviewed
See detailPhytoplankton Biomass and Production in the River Meuse (Belgium)
Descy, JP; Servais, P; Smitz, J.S. et al

in Water Research (1987), 21(12), 1557-1566

The biomass and production of the phytoplankton in a relatively unpolluted reach of the river Meuse (Belgium) were followed through two years (1983 and 1984).

Detailed reference viewed: 21 (3 ULg)