Papers by Jean-pierre Sweerts
Oxygen consumption in the profundal gyttja and littoral sands of Lake Vechten was determined with... more Oxygen consumption in the profundal gyttja and littoral sands of Lake Vechten was determined with pore-water analyses and core incubations. Methane (58-64%), ammonium (lo-13%), iron (2-6%), and sulfide (< 12%) oxidation accounted for-75% of the oxygen consumed in the profundal sediments. Almost the complete diffusive flux of CH, out of the anoxic layer into the oxic surface layer (7.9-9.4 mmol mm2 d-l) was oxidized, while only 27-36% of the NH,+ flux (5.1-5.2 mmol m-I d-l) was oxidized in the oxic surface layer and 64-73% diffused into the overlying water. In contrast to the profundal sediments, oxidation of reduced end products of anoxic respiration was of minor importance (< 15%) in littoral sandy sediments. Also, sediment oxygen consumption rate was higher in the profundal gyttja (29 mmol m-* d-l at 7°C) during overturn than in the littoral sandy sediments in both winter (8.7 mmol m-2 d-' at 7°C) and summer (18.6 mmol me2 d..' at 22°C). Poisoning the sediment cores with formaldehyde stopped bacterial activity, but oxygen profile measurements showed that this treatment does not reveal the bacterial or chemical nature of the oxidative processes.
Microbial biogeochemical activities in lakes: stratification and eutrophication
SIL Proceedings, 1922-2010, 1991
Microelectrode studies in immobilized biological systems
Interactions between the Nitrogen and the Sulfur Cycle Related to Mineralization Processes in Sediments
Aerobic and anaerobic mineralization in the littoral and profundal sedients of a stratified lake (Abstract)the measurement of production of phototrophic bacteria in deep layers
Limnology and Oceanography, 1986
Parts of the sandy littoral sediment of a Precambrian shield lake (Lake 302S) were intermittently... more Parts of the sandy littoral sediment of a Precambrian shield lake (Lake 302S) were intermittently covered with a layer of flocculent organic‐rich material 1–20 mm thick. Sandy sediments with flocculent surface sediment had higher rates of respiration (31–105%) and photosynthesis (37– 224%) than those without. Densities of invertebrate macrofauna were 10 times higher in the flocculent surface sediment than in the underlying sandy sediment, accounting for 17 vs. 5% of the total respiration. Microprofiles of oxygen concentration showed that almost all of the dissolved oxygen in the overlying water was consumed as it diffused through 5–7 mm of the flocculent surface sediment, so that the underlying sandy sediment was almost completely anaerobic in the presence of flocculent surface material. The presence of flocculent surface sediment also decreased the depth of penetration of sulfate into the sandy sediment since the zone of sulfate reduction was located closer to the sediment‐water in...
FEMS Microbiology Ecology, 1991
Phosphate uptake capacity of summer phytoplankton of the Loosdrecht Lakes in relation to phosphorus loading and irradiance
Hydrobiological Bulletin, 1986
... JEAN-PIERRE RA SWEERTS, HERMAN J. GONS, and MACHTELD RIJKEBOER ... 1). Light-irradiance depen... more ... JEAN-PIERRE RA SWEERTS, HERMAN J. GONS, and MACHTELD RIJKEBOER ... 1). Light-irradiance dependent phosphate uptake has been shown by FAUST and COR RELL (1976), RESHKIN and KNAUER (1979) and ZAISS (1985); LEAN and PICK (1981) did not observe ...
Sulfur cycling in a dutch moorland pool under elevated atmospheric S-deposition
Water, Air, and Soil Pollution, 1989
Atmospheric S deposition, sulfate reduction and the accumulation of reduced S components were inv... more Atmospheric S deposition, sulfate reduction and the accumulation of reduced S components were investigated in sediments of a Dutch moorland pool. Laboratory 35SO42- tracer experiments indicated that the variation in reduction rate with depth in the sediment could be described by an exponential fit, suggesting first order kinetics. Sulfate reduction rates calculated from a kinetic transport model were highest in
Onderzoek rond de kaderrichtlijn waterbeheer: Inventarisatie
Oxygen consumption, mineralization and nitrogen cycling at the sediment-water interface of north temperate lakes
The Framework Directive 76/464/EEC (4 May 1976; source: EC001 1) and its daughter Directives are ... more The Framework Directive 76/464/EEC (4 May 1976; source: EC001 1) and its daughter Directives are meant to control pollution caused by discharges of certain dangerous substances into the aquatic environment of the Community. The Directives have had to be transposed by the Member States into their national legislation within the time limits given by the Directives. The effect of implementation of the Directives on the quality of EC surface waters, however, had not yet been inventoried in a comprehensive way at Community level. The purpose of this project is to provide an evaluation of the impact of Directive 7 6/464/EEC on the quality of the main surface waters within the Community during the last 10-12 years. An analysis of changes in discharges and water quality for List I substances accompanied by an in-depth analysis regarding national and regional strategies and sanitation of industries, has been conducted for the main EC surface waters. The three new countries to join the EC (Austria, Finland and Sweden) have not been included as part of this study. The present study was commissioned by DGXI/C/5 in February 1994 to a Joint Venture comprising DELFf HYDRAULICS and the Institute for Inland Water Management and Waste Water Treatment (RIZA) the Netherlands (Contract B4-3040/93/001169/LP/A3). The study was supervised by Mrs. J. Vennekens, Mr. A. C. Marcelino and Ms. E. McDonnell of the European Commission (DGXI-C.5). The data acquisition and the interpretation of the data have been carried out in association with the National Experts of the Member States. The cooperation of the National Experts and their colleagues in providing necessary information has been critical for conducting this study and is gratefully acknowledged. iv References throughout the text are given by a country/location code followed by a 3-4 digit number (e.g. ECOOl). This non-standard manner of giving references has been chosen in order to allow references to be easily incorporated within the water quality data tables (Appendix E, Volume II). Full references per country are given in Chapter 8.
Micro-environment of chironomid larvae in the littoral and profundal zones of Lake Maarsseveen I, The Netherlands
Archiv für Hydrobiologie
Methane oxidation at the sediment-water interface of shallow eutrophic Lake Loosdrecht and deep meso-eutrophic Lake Vechten
SIL Communications, 1953-1996
The Use of Decision Support Systems in Water Management
The Inter-Relationship Between Irrigation, Drainage and the Environment in the Aral Sea Basin, 1996
Applied and environmental microbiology, 1989
NO(3) concentration profiles were measured in the sediments of a meso-eutrophic lake with a newly... more NO(3) concentration profiles were measured in the sediments of a meso-eutrophic lake with a newly developed microelectrode. The depth of penetration of NO(3) varied from only 1.3 mm in organic-rich profundal silty sediments to 5 mm in organic-poor littoral sandy sediments. The thickness of the zone of denitrification in the organic-rich sediments was <500 mum. Oxygen profiles measured simultaneously revealed that the zone of denitrification was directly adjacent to the aerobic zone. The results demonstrate high denitrification rates (0.26 to 1.31 mmol m day) at in situ nitrate concentrations in the overlying water (0.030 mmol liter) and limitation of denitrification by nitrate availability.
Water quality modelling of the western Scheldt estuary
Trace Metals in the Westerschelde Estuary: A Case-Study of a Polluted, Partially Anoxic Estuary, 1998
... The time and space dependent net transport of suspended solids is an input item to the model.... more ... The time and space dependent net transport of suspended solids is an input item to the model. It is supplied on a seasonally integrated basis, so that the effects of high discharges or storm events are included. ... Van Gils, JAG, MRL Ouboter &amp; NM De Rooij, 1993. ...
Application of an Integrated Management Approach to the Restoration Project of the Lagoon of Venice
Journal of Environmental Management, 1996
Freshwater Biology, 1989
1. The overlying water of intact sediment cores was constantly stirred with an impeller at a rate... more 1. The overlying water of intact sediment cores was constantly stirred with an impeller at a rate sufficient to mix turbulently the water column and maintain the diffusive boundary layer at a determined thickness. The system allowed standardization of water circulation in laboratory sediment core experiments. 2. Both oxygen concentration and oxygen penetration depth in the sediments decreased, the former by 10% and the latter from 4.2 mm to 2.0 mm, when the overlying water was not stirred for 24 h, as measured with oxygen microelectrodes in a lake sediment core. 3. Oxygen profiles measured in sediment cores in the laboratory were similar to those measured in situ when the overlying water was stirred with an impeller at such a rate that a similar thickness of the diffusive boundary layer at the sediment-water interface developed in the laboratory as that in siiii. 4. Sediment oxygen consumption was calculated from: (I) measured oxygen profiles in the diffusive boundary layer and the molecular diffusion coefficient for oxygen in water; (2) the measured oxygen decrease in the top of the sediments and the estimated diffusion coefficient in the sediment; and (3) by oxygen differences in the overlying water after incubation of sediment cores.
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Papers by Jean-pierre Sweerts