Occurrence and distribution of microplastics in marine sediments along the Belgian coast

Plastic debris is known to undergo fragmentation at sea, which leads to the formation of microscopic particles of plastic; the so called ‘microplastics’. Due to their buoyant and persistent properties, these microplastics have the potential to become widely dispersed in the marine environment through hydrodynamic processes and ocean currents. In this study, the occurrence and distribution of microplastics was investigated in Belgian marine sediments from different locations (coastal harbours, beaches and sublittoral areas).Particles were found in large numbers in all samples, showing the wide distribution of microplastics in Belgian coastal waters. The highest concentrations were found in the harbours where total microplastic concentrations of up to 390 particles kg⁻¹ dry sediment were observed, which is 15-50 times higher than reported maximum concentrations of other, similar study areas.The depth profile of sediment cores suggested that microplastic concentrations on the beaches reflect the global plastic production increase.     

Evidence for repeated re‐activation of old landslides under forest

Local reactivations of landslides in forests are rarely reported in landslide catalogues. The occurrence of hillslope sections with fresh morphological landslide features in forested old, deep‐seated landslides, however, suggests that landslide reactivations are not restricted to residential areas. In this study, a dendrogeomorphological analysis of beech stands was used to investigate the periods of reactivation of a deep‐seated rotational slide in the Koppenberg forest (Flemish Ardennes, Belgium). The relation to rainfall and the correspondence to landslide reactivations reported in a nearby built‐up area were also analysed. A dendrometrical study preceding the dendrochronological analysis proved that, compared with the nearby reference site, trees on the Koppenberg forest landslide site were significantly more inclined and showed more knees, indicating that the landslide site has not stabilized yet. As the sampled trees are younger than the landslide, dendrochronology did not allow determination of the year in which the landslide was initiated, but analysis of two different tree ring width parameters (i.e. ring eccentricity and growth change) calculated for trees sampled on the Koppenberg landslide and the reference site proved to be of great help in determining the temporal sequence of landslide reactivation. During the past 80 years, several periods indicative of local reactivations (i.e. 1943–1945, 1949–1952, 1967–1970, 1972–1977, 1979–1981, 1988–1997) were found within the investigated landslide, but delineation of the spatial extent of the reactivations during these indicative periods was not straightforward. These periods generally correspond to years with above‐average rainfall. Finally, the fact that at least 34% of the years indicative of reactivation of the Koppenberg forest landslide correspond to a year in which a landslide reactivation was reported in the Flemish Ardennes suggests that in built‐up areas, apart from anthropogenic interventions, natural triggering factors remain very important. Copyright © 2009 John Wiley & Sons, Ltd.     

MANUFACTURING RESEARCH AND DEVELOPMENT IN A PERIPHERAL REGION: THE CASE OF LIMBURG,BELGIUM *

The scope of manufacturing research and development (R&D) in the intermetropolitan region of Limburg, Belgium, is analyzed within the context of the spatial, organizational, and size-theoretical attributes of R&D and of the core-periphery model. In spite of its peripheral location, Limburg exhibits vivid R&D activity associated with the trickled-down manufacturing from neighboring West European industrial cores. R&D in Limburg is mostly centered in multinational/locational branch plants, but also in a few modernizing, old sector establishments engaged in high and medium-level “off the shelf” technology processes. R&D was significant in terms of spending, number of newly developed prototypes, and number of patents registered. It revealed strong sector concentration with relatively dispersed spatial patterns. R&D departments and spending disclosed a positive correlation with plant size, but showed particularly high concentration coefficients when medium-size high- and medium-level technology plants were considered.     

Cultural political economy: On making the cultural turn without falling into soft economic sociology

This article explores the implications of making the cultural turn in the engagement of economic and political geography with issues of political economy. It seeks to steer a path between a fetishistic, reified economics that naturalizes economic categories and a soft economic sociology that focuses on the similarities between economic and other socio-cultural activities at the expense of the specificity of the economic. We show how combining critical semiotic analysis with an evolutionary and institutional approach to political economy offers one interesting way to achieve this goal. An evolutionary and institutional approach to semiosis enables us to recognize the semiotic dimensions of political economy at the same time as establishing how and why only some economic imaginaries among the many that circulate actually come to be selected and institutionalized; and Marxian political economy enables us to identify the contradictions and conflicts that make capital accumulation inherently improbable and crisis-prone, creating the space for economic imaginaries to play a role in stabilizing accumulation in specific spatio-temporal fixes and/or pointing the way forward from recurrent crises. The paper illustrates these arguments with a case study on the Flemish ‘anchoring strategy’ as a specific regional economic development strategy. It concludes with a set of guidelines for the further development of cultural political economy.     

Modelling mean annual sediment yield using a distributed approach

In this paper a spatially distributed model for the calculation of sediment delivery to river channels is presented (SEDEM: SEdiment DElivery Model). The model consists of two components: (1) the calculation of a spatial pattern of mean annual soil erosion rates in the catchment using a RUSLE (Revised Soil Erosion Equation) approach; and (2) the routing of the eroded sediment to the river channel network taking into account the transport capacity of each spatial unit. If the amount of routed sediment exceeds the local transport capacity, sediment deposition occurs. An existing dataset on sediment yield for 24 catchments in central Belgium was used to calibrate the transport capacity parameters of the model. A validation of the model results shows that the sediment yield for small and medium sized catchments (10–5000 ha) can be predicted with an average accuracy of 41 per cent. The predicted sediment yield values with SEDEM are significantly more accurate than the predictions using a lumped regression model. Moreover a spatially distributed approach allows simulation of the effect of different land use scenarios and soil conservation techniques. Copyright © 2001 John Wiley & Sons, Ltd.     

Observations and predictions of hydromechanical coupling effects in the Boom clay,Mol Underground Research Laboratory,Belgium

The Boom clay is considered as a candidate host rock for the Belgian disposal of radioactive waste. Thanks to the recent sinking of a new shaft to extend the Underground Research Laboratory (URL) at the Mol site, new in-situ data have been obtained. They consist in the observation of significant fracturing, evidenced during the excavation of the shaft annexes, and in correlated hydraulic perturbations in the far field (maximum of 0.2 MPa at 60-m radius). These observations cannot be explained from simple poroplastic models that predict a maximum perturbation extent of 25 m under full deconfinement. Thus, models with increasing complexity are built to explain this discrepancy. It is proposed that the low-support pressure imposed by the primary lining, combined with the long time over which this support condition held, has favoured the decompression of the clay massif through time-dependent effects, mainly skeleton viscosity. This resulted in near-field fracturing, leading to an apparent increase of the excavated radius and to a hydraulic perturbation in the far field. This interpretation still needs to be validated/invalidated with future research. The effect on the overall performance of the repository is expected to remain small due to the self-healing nature of the fractures. Electronic Publication     

Modelling seasonal variations in nitrate and sulphate concentrations in a vulnerable alluvial aquifer

The Eisden–Meeswijk region in Belgium has been affected by mining subsidence due to the deep coal mining activities. Groundwater levels in the alluvial plain of the Meuse River are maintained below the ground surface by drainage installations and municipal well fields. A correlation between the water level in the Meuse River and the variation in nitrate and sulphate concentrations in the aquifer has been observed. A transient groundwater model is developed for the period May 1998–May 2002 and advective transport simulations have been carried out using this model. During dry periods, the major groundwater flow is directed towards the Meuse River, thereby feeding the river. During wet periods, however, groundwater flows in the opposite direction. Due to these variations in groundwater flow direction and to the extraction of groundwater, zones of higher solute concentration exist of which the position and extension vary both spatially and temporally.     

Biostratigraphy,sedimentology and palaeobathymetry of Waulsortian buildups and peri-Waulsortian rocks during the late Tournaisian regression,Dinant area,Belgium

Recent revision of the biostratigraphy allows the recognition of a stratigraphic entity (here termed Freyrian) between the base of the Moliniacian stage and the base of the Viséan and simplifies sedimentological interpretation of late Tournaisian events around Dinant, in Belgium. Petrographic analysis of Freyrian rocks in Waulsortian buildups and peri-Waulsortian facies reveals a pattern of carbonate sedimentation related to the submarine topography developed by the buildups, and to sea-level changes. Graded beds and thin layers of grainstone in the predominantly fine-grained peri-Waulsortian sediments represent influxes derived mainly from nearby buildups during a period of shallowing. Using the sequence of foraminiferan assemblages which colonized the buildups as a stratigraphic scale, the earlier influxes are shown to have occurred only close to the presumed source, whereas later influxes extended further and marked the culmination of the shallowing phase. Deposition during the latter part of the Freyrian appears to have occurred in rather deeper, less disturbed water. The Moliniacian and Viséan boundary stratotypes, both in peri-Waulsortian facies, are critically assessed because almost all the stratigraphically useful foraminiferans occur in the rare grainstones resulting from sediment influxes. Tetrataxis was one of the few foraminiferans to colonize proximal peri-Waulsortian areas and appears to have ranged to a water depth of about 200 m. Downslope diachronism of colonization is interpreted as evidence of a sea-level fall of about 140 m and is used to draw a sea-level curve for this late Tournaisian regression. Using the same depth scale, microbial coating extended to about 300 m and its development appears to have been related to low sedimentation rates rather than photic conditions. © 1997 John Wiley & Sons, Ltd.     

Recovery scenarios for deep over-exploited aquifers with limited recharge: methodology and application to an aquifer in Belgium

Recharge of deep-seated aquifers must be provided through leakage from overlying geological formations and can be very limited. Although hydraulic characteristics of these aquifers may be favorable for extensive exploitation, the renewability of the groundwater resource may be very restricted and only significant on long time scales. Over-exploitation of such aquifers leads to steadily declining piezometric levels and water balancing and steady state conditions are not to be expected on the short term. Recovery of such systems is very difficult, also because of the socio-economic dependencies of the water resource and the long time it requires to replenish the system. Management plans for restoration should be based on the transient hydrodynamical behaviour. A recovery plan should be developed based on results of a groundwater flow model. In a first step must be simulated how long it will take for the aquifer system to fully recover by natural recharge. As this will most often be a very long time it can be cancelled out as a realistic scenario. An alternative objective is to be formulated which could be achieved in the near future on a time scale of years or decades. Using model simulations, reduction schemes of exploitation rates shall be quantified that will allow to reach these defined goals, such as raising piezometric levels above the top of the aquifer itself or above the top of the overlying geological unit. The methodology is illustrated with an example of a deep hard rock aquifer in Belgium where piezometric levels have dropped below the top. The objective here was to raise the levels again above the top within the next 50 years. However, this is not accomplished by balancing aquifer recharge and discharge, but is reached by a lateral redistribution of the water over the aquifer extent. A full recovery of this aquifer would require at least a century with only a very limited amount of exploitation.