Publications of Alain Hambuckers
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See detailBiodiversité
Hambuckers, Alain ULiege

in Marbaix, P.; van Ypersele, J.-P. (Eds.) Imapcts des changements climatiques en Belgique (2004)

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See detailProduction of selenium-enriched grass and haylage by mineral fertilisation in southern Belgium
de Behr, V.; Coenen, M.; Hambuckers, Alain ULiege et al

in Proceedings of 7th Conference of the European Society of Veterinary and Comparative Nutrition (2003)

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See detailWatershed Liming in the Belgian Ardennes : Effects on soil solution and streamwater chemistry
Carnol, Monique ULiege; Hambuckers, Alain ULiege; Remacle, Jean ULiege

Conference (1997, June)

Forest liming has received increased attention in the 1980s, when unusual needle yellowing and fall were observed in large parts of Europe and North America. This ‘new forest decline’ has been attributed ... [more ▼]

Forest liming has received increased attention in the 1980s, when unusual needle yellowing and fall were observed in large parts of Europe and North America. This ‘new forest decline’ has been attributed to several causes acting individually or synergetically, amongst which were acidification, N saturation and nutritional imbalances. This time, liming did not aim at increased productivity, but as a counteracting measure to the soil acidification and to remove nutritional imbalances. The Belgian Ardennes were not exempt from this phenomena and symptoms of forest dieback were reported in 1983 by Weissen (Weissen et al.,1983). Soils are naturally poor in magnesium and the observed dieback was supposed to be the consequence of increased pollution exacerbating the deficiency in magnesium. A reduction in productivity and financial losses were predicted. Liming was suggested for prevention and correction, however possible side effects, in particular on soil solution (tree nutrition) and stream water chemistry (drinking water) needed to be evaluated. In this paper, we present results from a case study in four Picea abies watersheds in southern Belgium. The paired watersheds of approximately 80 ha were situated in the ‘Haute Ardenne’ and in the ‘Ardenne occidentale’ regions, on acid brown soils. One watershed of each pair was limed with 3 T/ha of fine ground dolomite ((Ca,Mg)CO3) 55/40 and 200 kg/ha K2SO4 in 1992 and 1993, respectively. Rainfall, throughfall and monolith lysimeter soil solution were analysed at monthly intervals, and runoff chemistry at two-weekly intervals (volume-weighed reconstructed daily samples). Time series intervention analysis was used as a tool to detect statistically significant changes in stream water chemistry due to the liming event, and fluxes were calculated to evaluate losses of the applied dolomitic lime to the catchment stream. Dolomite dissolution distinctively affected streamwater chemistry in the watershed situated in the Hautes Ardennes (Waroneu). Magnesium concentrations increased immediately after liming, most likely due to surface runoff. Four years after liming, concentrations were still higher than prior to liming. However, the proportions of magnesium lost were relatively low compared to the dose applied. Calcium concentrations did not change after liming in either catchment, nor did the concentrations of the major cations and anions measured. In the monolith lysimeters, magnesium concentrations increased immediately after liming under the organic horizons, and one year after liming under the mineral horizons. Calcium concentrations increased only three years after the application of lime under the organic and mineral horizons. These results led to the conclusions that for the soils under study and the doses applied, a major part of the lime was retained by the soil system, and that consequences on water chemistry were minor. [less ▲]

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See detailTrace metal transfers between water and sediment in a freshwater system. Influence of microbial activity
Hambuckers-Berhin, Françoise; Hambuckers, Alain ULiege; Remacle, Jean

in Studies in Environmental Science (1997), 68(353-368),

The purpose of our work was to determine, in a freshwater batch system, the importance and the direction of trace metal transfers between sediment and water as influenced by bacterial activity. Sediment ... [more ▼]

The purpose of our work was to determine, in a freshwater batch system, the importance and the direction of trace metal transfers between sediment and water as influenced by bacterial activity. Sediment was incubated in Meuse water in different conditions. Net transfer occurred on an average from sediment to water for Co, Cs, Cr, Cu, Hg, La, Ni, Zn and from water to sediment for Bi, Cd, Pb, Sb, Tl. Positive correlations between oxygen consumption and transfer of nine metals from sediment to water demonstrate the influence of bacterial activity. Correlations of the metal transfer either with water pH or with the variation of sediment weight at the end of incubation led to suppose that the alteration of the chemical conditions also strongly influenced the transfers. It was confirmed by the comparison of chemical characteristics of the water and of the sediment at the end of incubation in contrasted conditions. The uptake of 12 metals by a bacterial community isolated from the sediment was related to metal concentrations in the water. The specific transfer from the water to the bacterial biomass was appraised in the sediment incubation experiments. It allowed to compute the net metal transfer of 12 metals from the sediment to the water with significant bacterial activity. The comparison of these values with the transfers occurring at 4°C, i.e. with reduced bacterial activity, demonstrated that the transfer of 11 metals from the sediment to the water is clearly enhanced by bacterial activity. [less ▲]

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See detailIS THE PRESENCE OF MESOTROPHIC PLANT-COMMUNITIES IN THE PEAT-BOGS OF HAUTES-FAGNES (BELGIUM) CONNECTED WITH TONALITE INTRUSIONS IN THE REVINIAN LAYERS
Hambuckers, Alain ULiege; Schumacker, René ULiege; Remacle, Jean ULiege et al

in Belgian Journal of Botany (1995), 128(1), 48-56

Within the Hautes-Fagnes Nature Reserve (Belgium) acidic and oligotrophic biotopes are developing on very acidified stony silt raised bogs. However, they are locally dominated by mesotrophic species ... [more ▼]

Within the Hautes-Fagnes Nature Reserve (Belgium) acidic and oligotrophic biotopes are developing on very acidified stony silt raised bogs. However, they are locally dominated by mesotrophic species. Based on the fact that there are several outcrops of tonalite in the region and particularly one in the Nature Reserve, a hypothesis to explain these singularities of the vegetation implies discontinuities of the bedrock provoked by intrusions of this magmatic rock in the Revinian layer covering the region. Seventeen plots containing Phragmites australis were examined and vegetation was described. Silt and soil water were sampled and analyzed for mineral contents in 15 sites. The differences of mineral composition between the P. australis plots and their surrounding environment confirmed the more mesotrophic characteristics of these plots (i.e. higher pH, higher Ca and Mg contents, lower Al content). However, the lower Zn, Pb and Fe contents would lead to reject the hypothesis of intrusions of tonalite since these elements are more abundant in the tonalite and its mineralization than in the Revinian rock. Nevertheless, the overall ecological conditions of the examined plots and the differences of plant species composition suggested that the observed chemical environment could be evoked for explaining the distribution of the mesotrophic species in the oligotrophic environment of the Nature Reserve. Consequently, an alternative hypothesis is proposed. [less ▲]

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See detailRelative importance of factors controlling the leaching and uptake of inorganic ions in the canopy of a spruce forest
Hambuckers, Alain ULiege; Remacle, Jean ULiege

in Biogeochemistry (1993), 23(2), 99-117

Sequential sampling of precipitation under mature spruce trees and time-series analysis of the data were performed in order to assess, in natural conditions, the relative importance of different factors ... [more ▼]

Sequential sampling of precipitation under mature spruce trees and time-series analysis of the data were performed in order to assess, in natural conditions, the relative importance of different factors that could influence the leaching and uptake of inorganic ions in the canopy. Eleven rain events were analyzed in order to estimate how external factors, rain intensity, H+, and ionic concentration of the incident rain influence the ionic throughfall concentrations and the net throughfall fluxes. The results led to the conclusion that leaching or uptake mostly occur by diffusion. The influence of the open rain acidity was not conclusive; however, it was shown that the tested external factors only controlled a few percent of the variation of the data. By contrast, the autocorrelation of the data always explained a large portion of the variance. lt could result from the gradual changes in the course time of internal factors related to the exchange system including waxes, cuticles, apoplast and xylem sap. These constituents were known to control the exchange at the canopy surface and to be sensitive to the plant physiology and environmental conditions. [less ▲]

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See detailThe role of the bacterial community in the radionuclide transfers in freshwater ecosystems
Hambuckers-Berhin, Françoise; Hambuckers, Alain ULiege; Remacle, Jean ULiege

in Studies in Environmental Science (1993), 55(337-353),

This chapter investigates the radionuclide fluxes between the bacteria and the water in aquatic ecosystem by examining the bulk transfers mediated by a bacterial community isolated from the river ... [more ▼]

This chapter investigates the radionuclide fluxes between the bacteria and the water in aquatic ecosystem by examining the bulk transfers mediated by a bacterial community isolated from the river sediments. A comparison of the aerobic bacterial communities colonizing the sediments and the water column shows that the bacterial community of the sediments is composed of two sub-communities. The first one is similar to the water column community by its biochemical features; the other one displays quite different characteristics and appears to be more representative of the sediments. An important part of 60Co and 134Cs can be immobilized by the bacterial biomass that constitutes a pool of radionuclides, their transfers to the water column being controlled by temperature and pH. The uptake of 60Co and 134Cs by bacteria is described by the Michaelis–Menten model. The uptake kinetics depend on the type of radionuclide and the level of radiocontamination in the water column. The highest affinity uptake system is observed for 60Co at low radiocontamination levels. The decontamination of bacterial biomass develops in two phases. The first phase is characterized by a very short biological half-life, a few seconds or minutes, while the second phase is longer; the biological half-lives reach between 15 h to 461 h for 60Co and between 39 h and 8,976 h for 134C [less ▲]

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See detailTime series analysis of the nutrient concentrations of the water flowing through a forested watershed: trend and causal link detection
Hambuckers, Alain ULiege; Remacle, Jean ULiege

in Vander Borght, Paul; Tychon, Bernard (Eds.) Gestion de l'azote agricole et qualité des eaux. Acte du séminaire spécialisé (1992)

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See detailNutritional status of declining spruce (Picea abies (L.) Karst.) - Effect of soil organic matter turnover rate
Hambuckers, Alain ULiege; Remacle, Jean ULiege

in Water, Air and Soil Pollution (1991), 59(1-2), 95-106

Foliar analysis was undertaken in two plots of Picea abies (L.) Karst., located in a watershed of Haute Ardenne, Belgium, in order to estimate the decline of the trees. Apart from a general Mg deficiency ... [more ▼]

Foliar analysis was undertaken in two plots of Picea abies (L.) Karst., located in a watershed of Haute Ardenne, Belgium, in order to estimate the decline of the trees. Apart from a general Mg deficiency, the concentrations of the needles were in the same range as those determined in other European stands. Comparisons between healthy and declining trees within each plot revealed a general pattern of decline similar to that observed elsewhere in Western Europe. This was shown as lower Ca, Mg, Zn concentrations and water content and higher N and P concentrations of the needles collected from declining trees. It is concluded that this decline could be due to N over fertilization by the atmospheric deposition. The difference of decline between the two plots was attributed to the turnover rate of the soil organic layer which was less intensive in the most damaged plot. [less ▲]

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See detailA Decennial Control Of N-Cycle In The Belgian Ardenne Forest Ecosystems
Weissen, F.; Hambuckers, Alain ULiege; Vanpraag, Hj. et al

in Plant and Soil (1990), 128(1),

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