• k-Waarde schatting aan geroerde grondmonsters in het Overijsselse Vecht-gebied

      Mesters-Bakhuis; H. (1985-05-31)
      Abstract not available
    • Kalibratie van Ellenbergs milieu-indicatiegetallen aan werkelijk gemeten bodemfactoren

      Alkemade JRM; Wiertz J; Latour JB; LBG (1996-05-31)
      A multi-stress model has been developed in the Netherlands on a national scale to forecast changes in plant species composition due to acidification, eutrophication and dessication. This model, called SMART-MOVE, consists of: a soil module (SMART2) used for calculating changes in groundwater level, pH and nutrient availability, and a vegetation module, consisting of regression equations that describe the relationships between the probability of occurrence and environmental factors. These environmental factors represent average Ellenberg indication values for pH, availability of water and nutrient availability. Salinity was also included since in large parts of the Netherlands salinity is of major importance for species composition. Essential input data for these modules, such as groundwater level and seepage flux, can be calculated with the National Groundwater Model, for example. In this study relationships were calculated between the Ellenberg indication values and the relevant soil factors: pH, average spring groundwater table, biomass production, nitrogen production, concentrations of several nutrients and chloride concentration for both terrestrial and aquatic systems. Where it was possible to use a sigmoid model, to cope with the original ordinal and limited scale of indication values, the explained variance increased by 5-10%. In the regression analyses, almost 7000 vegetation releves from a variety of ecosystems could be used, satisfying relationships with Ellenberg values were found for pH, average spring groundwater table and biomass and nitrogen production. These relationships are used to connect the soil module with the vegetation module and quantify the confidence of the model outcomes. Average Ellenberg indication values can be concluded to be succesful as estimates for the abiotic conditions in models like SMART-MOVE.
    • Kalibratie van Ellenbergs milieu-indicatiegetallen aan werkelijk gemeten bodemfactoren

      Alkemade JRM; Wiertz J; Latour JB; LBG (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1996-05-31)
      Momenteel wordt een multiple stress model ontwikkeld waarmee op nationale schaal de kans op voorkomen van plantesoorten wordt voorspeld als gevolg van verdroging, verzuring en vermesting (SMART-MOVE). Het model bestaat uit een bodemmodule (SMART) en een vegetatie module (MOVE). Essentiele invoergegevens voor deze modules, zoals grondwaterpeil en kwelflux kunnen worden berekend met bijvoorbeeld het LGM (Landelijk Grondwater Model). Met de vegetatie-module kan de kans op voorkomen van een soort bepaald worden aan de hand van ecologische amplitudes van de plantesoorten. De ecologische amplitudes zijn weergegeven op een milieu-as die weergegeven is in gemiddelde indicatie-getallen van Ellenberg per proefvlak. In dit rapport wordt een ijking uitgevoerd van deze semi-kwantitatieve milieu-as aan daadwerkelijk gemeten bodemfactoren zoals de zuurgraad (pH), de grondwaterstand (GVG: gemiddelde voorjaarsgrondwaterstand), gehalten van nutrienten (b.v. nitraat en fosfaat- gehalten), primaire productie (gemeten in biomassa opbrengst en stikstof-opbrengst) en het chloride gehalte. Hiervoor is behalve van de hiervoor doorgaans toegepaste lineaire regressie analyse ook gebruik gemaakt van non-lineaire regressie analyse met een S-vormig model als uitgangspunt. In totaal konden bijna 7000 opnamen worden gebruikt. Voor pH, GVG, biomassa opbrengst en stikstof opbrengst bleken de R2-waarden zodanig hoog dat vertaling van de gemiddelde Ellenberggetallen naar gemeten waarden vrij goed mogelijk is. Deze relaties worden gebruikt voor de koppeling tussen de vegetatiemodule en de abiotische modules. Daarnaast dragen zij bij aan een betere kwantificering van de betrouwbaarheid van de modeluitkomsten. Het gemiddelde milieu-indicatiegetal van Ellenberg lijkt voor modellen zoals SMART/MOVE een bruikbare schattingsmethode van de abiotisch milieucondities.
    • Kalibratie van het programma CAR II aan de hand van metingen van het Landelijk Meetnet Luchtkwaliteit van het RIVM

      Wesseling JP; Sauter FJ; LVM (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 2007-07-20)
      Research by the National Institute for Public Health and the Environment (RIVM) has shown that concentration levels calculated using the CAR II model are systematically too high. Application of a new calibration strongly improves the match between calculated and measured concentration levels. Local authorities employ the CAR II (Calculation of Air pollution from Road traffic) model in order to determine concentration levels in streets. Since 2007 a new set of emission factors for road traffic has become available. For several substances the emissions are significantly higher than they were before. Using these emission factors in CAR II leads to substantial discrepancies between calculated and measured concentration levels. By request of the Ministry of Housing, Spatial Planning and the Environment (VROM) the RIVM has determined a new calibration for CAR II. Based on traffic infoation provided by municipalitie, calculations were performed using CAR II for the years 2003 - 2006 for those streets where a measuring station of the national air quality measuring network of the RIVM is located. The results of the calculations for nitrogen (di)oxide, carbon monoxide and particulate matter were compared with measurements during the same period. From this comparison it became clear that calculated concentration contributions must be multiplied by 0.62 in order to obtain a good agreement with the measured concentrations. As the emission factors that are used in CAR II have also changed in 2007, the calculated total concentration levels are not very different from those obtained during the last few years.
    • Kalium inname: risico van hyperkaliëmie? : Overzicht van beschikbare gegevens in Nederland

      Hendriksen M; van Rossum C; van der A D; DCZ; V&Z (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 2015-07-20)
      Potassium has a beneficial effect on blood pressure levels because it counters the blood raising effect of sodium (NaCl, 'salt'). Important sources of potassium are fruit and vegetables, potatoes and meat. It is nearly impossible to get an overdose of potassium from natural food sources. Almost the entire daily intake of potassium is excreted by the kidneys in healthy individuals. The most important group at risk of developing abnormal high levels of potassium in the blood (hyperkalaemia) are patients with severe kidney damage. They need to follow a potassium-restricted diet. Severe hyperkalaemia can be lifethreatening because it can cause cardiac arrhythmias, cardiac arrest or muscle weakness. Other groups could potentially be at risk for developing hyperkalaemia by a combination of factors. For instance, individuals at risk are those who are not aware they have impaired renal function and at the same time take supplemental potassium or use certain medications such as ACEinhibitors (heart medications) or potassium-sparing diuretics. The magnitude of this risk relative to the current potassium intake in the Netherlands is yet unknown. To answer this question more research is needed. These results have been demonstrated in an inventory performed by the RIVM commissioned by the Ministry of Health, Welfare and Sport. In this inventory, available data on potassium intake in the Netherlands and the potential risk groups for developing hyperkalaemia are described. The Health Council of the Netherlands is currently preparing a new advisory report Guidelines for a Healthy Diet for which this information will be used. his study was performed in the context of the high salt consumption of people in the Netherlands. To stimulate a healthy diet, the Dutch government has made voluntary agreements with the food industry to contribute to a lower salt intake by decreasing the salt (as sodium chloride) levels in processed foods. One method to reduce the salt content of foods is by using salt substitutes, such as potassium chloride.
    • Kankerclusters : GGD-richtlijn medische milieukunde

      Hegger C; IMG; mev (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 2012-05-31)
      The National Institute for Public Health and the Environment (RIVM) has updated the Municipal Public Health Services (GGD) guideline for cancer clusters in the Netherlands. This guideline consists of a phased plan that is implemented when the GGD receives notification from residents that a relatively high number of cancer cases have occurred in a particular neighborhood. In such instances, an environmental cause is often suspected. The aim of the guideline is to provide answers quickly and efficiently to the questions and worries that are currently circulating and to dispel any unnecessary anxiety in the population. Between 2005 and 2010, the GGDs in the Netherlands received about 40 notifications of this kind each year. Content of guideline: The updated guideline contains both the theoretical background on how to deal with notifications of cancer clusters and provides advice on how the guideline should be used in practice. The guideline describes which data are necessary for this and indicates the focus points for risk communication. For each phase of the plan, examples from daily practice are provided. Added to the guideline is a method for predicting the highest number of people who could develop cancer in a neighborhood. This is done by studying the national cancer data and the population make-up in a neighborhood. Three phases: The phased plan consists of three phases: the orientation phase, the inventory phase and the quantitative analysis. In each phase, attention is paid to any unanswered health and/or environmental issues and their possible links. Although the start of the phased plan is simple, it can be expanded wherever necessary by moving on to the next phase. The involvement of the GGD increases with each phase. The next phase of the plan starts only when the previous phase has deemed this necessary.
    • De kans op infectie en ziekte na het eten van schelpdieren, besmet met Campylobacter lari - een orienterende studie

      Teunis PFM; Havelaar AH; Vliegenthart JS; Roessink GL; MGB (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1996-03-31)
      Voor schatting van de gezondheidsrisico's bij de consumptie van rauwe schelpdieren, besmet met Campylobacter lari, zijn kwantitatieve gegevens nodig over de dosis en de dosis-responsrelatie. In dit onderzoek zijn aantallen C. lari in rauwe oesters en mosselen geschat uit gegevens van een Most Probable Numbers (MPN)-test met 1 verdunning. Samen met gegevens over het aantal schelpdieren in een portie en de gewichtsverdeling van oesters/mosselen, kan hiermee de dosis pathogenen in een portie oesters/mosselen geschat worden. Voor Campylobacter lari zijn geen dosis-responsgegevens bekend, daarom zijn gegevens uit een vrijwilligersexperiment met C. jejuni gebruikt voor schatting van het infectierisico. Het mediane risico op infectie door C. lari na het eten van een enkele portie rauwe schelpdieren blijkt dan 2-10% (oesters) of 5-20% (mosselen) te zijn, afhankelijk van het tijdstip binnen het seizoen. Onzekerheidsanalyse leidt tot een 95% bovengrens voor het infectierisico van 60% . Uitgaande van gegevens voor C. jejuni zou de kans op acute gastro-enteritis na infectie tot 20% kunnen bedragen, zodat de geschatte mediane kans op ziekte 0.4-2% (oesters) of 1-4% (mosselen) zou kunnen zijn. Voor de consumptie van rauwe schelpdieren zijn geen bevolkingsgegevens bekend, zodat de geschatte risico's niet kunnen worden vertaald in mogelijke incidenties. Het is echter wel mogelijk om het risico na herhaalde blootstelling te berekenen: maandelijkse consumptie van een portie rauwe schelpdieren gedurende een kompleet seizoen leidt tot een geschatte kans op infectie van 50% (voor oesters, voor mosselen 60% . Na koken mag aangenomen worden dat besmette mosselen veilig zijn voor consumptie, mits het standaardrecept wordt gevolgd, en de mosselen niet gegeten worden, onmiddellijk na het openen van de schelp. De hier gegeven analyse geeft duidelijk aan dat er grote behoefte is aan meer kwantitatieve gegevens omtrent concentraties van pathogenen, consumptiepatronen, en dosis-responsrelaties, om de betrouwbaarheid van de geschatte risico's te verbeteren.
    • De kans op infectie en ziekte na het eten van schelpdieren, besmet met Campylobacter lari - een orienterende studie

      Teunis PFM; Havelaar AH; Vliegenthart JS; Roessink GL; MGB (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1996-03-31)
      In order to assess health risks caused by consumption of raw shellfish contaminated with Campylobacter lari, quantitative information on the dose and the dose response relation is required. In this study, numbers of C. lari, present in raw oysters or mussels, are estimated from a single dilution, five tube MPN assay. Together with assumptions about numbers of shellfish in a portion, and the weight distribution of shellfish, this enables estimation of the dose present in a single portion of raw oysters/mussels. In the absence of dose response data for C. lari, data for Campylobacter jejuni have been used to estimate the risk of infection. The median risk of infection by C. lari after eating a single portion of raw shellfish then appears to be 2-10% (oysters) or 5-20% (mussels), dependent on the time within the season. Uncertainty analysis leads to an upper 95% limit for the infection risk of 60%. Based on information on C. jejuni, the risk of acute gastro-enteritis after infection may be as high as 20%, leading to estimated median illness risks of 0.4-2% (oysters) and 1-4% (mussels). Population data on the consumption of raw shellfish are not available ; therefore these risks cannot be translated into possible incidences. However, it is possible to estimate the risk of repeated exposure: monthly consumption of a portion of raw shellfish during one complete season leads to a risk of infection as high as 50% (oysters, for mussels 60%). Cooking may be assumed to render the contaminated mussels completely safe for consumption, provided this is performed according to standard recipe, and the mussels are not eaten immediately after opening the shells. The present calculations clearly show that, in order to enhance the reliability of the risk estimates, there is a strong necessity for more quantitative data on pathogen concentrations, consumption patterns, and dose response relations.<br>
    • Kans op overschrijding van wettelijke grenswaarden langs het hoofdwegennet na snelheidsverhogingen in 2016

      Wesseling J; van Zanten M; Nguyen L; OIM; M&V (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 2016-11-09)
      In 2016 the speed limit on 29 stretches of highway has been increased to 130 kilometers per hour. As a result of the higher speed cars emit more pollutants into the air. In practice, the increased contributions from traffic to the concentrations in the air are compensated in many places by the continued improvement of air quality during recent years. Along a few kilometers of road, the increase in speed results in a poorer local air quality. In all cases, the concentrations, calculated using the official methods, remain below the European limit values. However, lower concentrations of pollutants in the air improve public health, even at concentration levels below the European limit values. This can be concluded from an analysis conducted by the RIVM at the request of the Ministry of Infrastructure and the Environment. Along the routes where speed has been increased the nitrogen dioxide and particulate matter concentrations were investigated at 71159 locations. Compared to 2015, concentrations of nitrogen dioxide in 2016 were lower at 84 percent of the surveyed locations. At approximately 4000 of the surveyed sites, or 5.5 percent, local air quality has deteriorated because of the speed increase. Locally the likelihood to exceed the limit value for nitrogen dioxide increased. Statistically, 12 additional exceedances of the legal limit value are expected. For particulate matter, there is no substantial increased risk of exceeding the limit value after increasing the speed limits. On March 3, 2016 representatives in the Dutch House of Parliament filed a motion to investigate whether and to what extent implemented increases in speed limits in 2016 lead to additional exceedances of the legal limits for air quality (motion 30175, No. 231). To answer the question, the RIVM has calculated concentrations of air pollutants along the road sections with speed increases for the years 2016 and 2020.
    • Kant-en-klaar maaltijden ; gehalte aan ijzer, selenium, natrium (zout) en kalium

      Vaessen HAMG; Ooik A van; Vliet JJH van; ARO (1994-06-30)
      Iron, selenium, sodium and potassium have been determined in 46 samples of convenience meals of which 32 were of the dried instant type and 14 of the cold-fresh type. Quality assurance included duplicate, and occasionally triplicate, analyses of samples and assay of the reference material "Mixed Human Diet" of IAEA/Vienna for the analytes involved. In addition, the BCR (EU/Brussels) reference material "Wholemeal Flour" was analysed frequently for iron and selenium. Results confirmed that both precision and accuracy of the determinations are at the required level. On average the dried instant type meals contain 33.9 mg/kg of iron, 122 mug/kg of selenium, 10.9 g/kg of sodium and 8.8 g/kg of potassium. Mean levels in cold-fresh type meals are 8.3 mg/kg of iron, 46 mug/kg of selenium, 4.0 g/kg of sodium and 1.7 g/kg of potassium. The two types of convenience meals studied hardly differ, on average, in iron and potassium content per helping. In general, helpings of cold-fresh type meals do contain 60% more selenium and sodium then instant dry type meals do. Consuming a single helping of an average convenience meal implies an intake of over 60% of the amount of salt per day which nutritional experts consider adequate. The molar sodium/potassium-ratio is on average 3.6 and ranges from 0.4-12.7. Both a high salt intake and a sodium/potassium-ratio of over 1 are considered potential risk factors for the incidence of hypertension. An average helping of the convenience meals studied contains too much salt and drops short of the nutrients considered. Responsible health authorities are urgently requested to come to an agreement with the manufacturers of these products on a package of minimum quantity and nutritional quality per convenience meal helpings.
    • Karakterisering van de zuurgevoeligheid van Salmonella typhimurium faagtype DT104

      Jonge R de; Leusden FM van; Dufrenne JB; Ritmeester WS; Delfgou-van Asch EHM; Pelt W van; LBG (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1999-03-01)
      Het aantal gevallen van salmonellosis in Nederland veroorzaakt door Salmonella typhimurium faagtype DT104 is toegenomen van 10 in 1985 tot 163 in 1997 (10% van alle gevallen van salmonellosis). De stam lijkt zijn oorsprong te hebben in het Verenigd Koninkrijk. Daar wordt inmiddels 20% van alle gevallen van salmonellosis veroorzaakt door deze stam. S. typhimurium DT104 is multiresistent en komt voor in veel productiedieren. Het veroorzaakt ernstige ziekteverschijnselen bij koeien en varkens. Humane infecties met dit faagtype lijken ernstigere gevolgen te hebben dan infecties met non-DT104 stammen. De resultaten van een case-control studie in Engeland lieten zien dat een ongewoon hoog percentage van geinfecteerden moest worden opgenomen in een ziekenhuis. Met S. typhimurium DT104 besmet voedsel komt via de mond en maag terecht in de dunne darm. Hier vindt invasie plaats van epitheelcellen. Faagtype DT104 is echter niet invasiever dan andere S. typhimurium. De ernstigere gevolgen van een infectie met deze stam zijn mogelijk het resultaat van een verhoogde resistentie tegen het zure milieu in de maag, waardoor de dosis die uiteindelijk in de dunne darm terecht komt, hoger is, en/of zijn het resultaat van een verhoogde virulentie, als gevolg van een verblijf in de maag. De resultaten in dit rapport laten zien dat isolaten van S. typhimurium DT104 ongevoeliger zijn voor milieus met een lage pH dan andere salmonella's.
    • Karakterisering van de zuurgevoeligheid van Salmonella typhimurium faagtype DT104

      de Jonge R; van Leusden FM; Dufrenne JB; Ritmeester WS; Delfgou-van Asch EHM; van Pelt W; LBG (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1999-03-01)
      Reports in the UK on human isolates of Salmonella typhimurium indicate that the number of isolates had increased from 87 in 1989 to over 3600 in 1996. They were all shown to be resistant to at least five antibiotics. In the Netherlands the number of cases of acute gastro-intestinal disease caused by S. typhimurium DT104 increased from 10 in 1985 to 163 in 1997. S. typhimurium DT104 is present in all types of animals used for production. It causes severe disease in cattle and pigs. Human infections due to this foodborne type of salmonella seem to be more severe than infections due to other types of S. typhimurium. Following oral ingestion and passage through the stomach, S. typhimurium invades epithelial cells of the small intestine. S. typhimurium DT104, however, is not shown to be more invasive than other salmonellas. The more severe symptoms associated with an infection with S. typhimurium DT104 might be dose-related. If S. typhimurium DT104 is shown to be more acid-resistant, the number of cells surviving the stomach is higher. The results presented in this report clearly show that some isolates of Salmonella typhimurium phage type DT104 are resistant to low-pH environments.<br>
    • Karakterisering van drie nieuwe DES-antiseria opgewekt bij konijnen tegen DES-BSA immunogeen

      Jansen EHJM; van den Berg RH; van Ginkel LA; Stephany RW (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1985-11-30)
      In dit rapport wordt de ontwikkeling en karakterisering beschreven van 3 nieuwe antisera tegen diethylstilbestrol (DES). De synthese is beschreven van het hapteen DES-mono-carboxypropylether en van het DES- immunogeen dat bereid werd door koppeling van het hapteen aan runder serum albumine (BSA). Met dit DES-BSA complex werden 3 konijnen geimmuniseerd. Na 3 maanden werden antisera verkregen met een hoge specificiteit voor DES. De kruisreactiviteit van de stilbeenderivaten dienestrol (DE) en hexestrol (HEX) is zeer laag. De specificiteit is ook getest onder routine omstandigheden door bepaling van het schijnbare DES-gehalte van praktijk monsters urine verrijkt met bekende hoeveelheden DE of HEX.<br>
    • Karakterisering van een humaan luteiniserend hormoon preparaat met behulp van fysisch chemische, immunochemische en in vitro biologische technieken

      van Ginkel LA; Loeber JG (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1984-08-01)
      Een humaan luteiniserend hormoon (hLH) preparaat werd met behulp van chromatografische (HPLC) en elektrofocussings (IEF) technieken op heterogeniteit onderzocht. Met name IEF bleek zeer bruikbaar bij het aantonen van verschillende componenten. In de pH gradient pH = 3,5 - 10 konden 13 componenten worden aangetoond. Deze componenten werden met behulp van immunochemische in in vitro biologische technieken gekarakteriseerd. De invloed van incubatie van hLH in oplossing bij 37 graden C op het scheidingspatroon werd onderzocht. Hierbij werd een relatie gelegd tussen de responsveranderingen van de verschillende componenten en bovengenoemde karakteristieken.
    • Karakterisering van een humaan luteiniserend hormoonpreparaat met behulp van fysisch-chemische, immunochemische en in vitro biologische technieken. II Combinatie van gelfiltratie chromatografie en isoelektrofocussing

      van Ginkel LA; Loeber JG (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1985-02-27)
      Een humaan luteiniserend hormoon (hLH) preparaat werd met behulp van chromatografische (gelfiltratie) en elektrofocussings technieken op heterogeniteit onderzocht. Subunits en LH werden bereid door incubatie van het preparaat (NM14) bij 37 graden C. Door middel van gelfiltratie chromatografie werd een subunit fractie en een gezuiverde intact LH fractie verkregen. In totaal konden 4 intacte, 4 - subunit en 8 - subunit componenten worden aangetoond. Het is gebleken dat met behulp van Scatchard analyse in een aantal gevallen nuttige aanvullende informatie over de samenstelling van een fractie kan worden verkregen.<br>
    • Karakterisering van regionale concentratievelden van ammoniak 2e fase; vergelijking gemeten concentraties en modelberekeningen

      Bleeker A; Jaarsveld H van; Duyzer J; LLO; TNO-MEP; Apeldoorn (1998-03-31)
      In this report a comparison was made between measured and calculated concentrations of ammonia. The measurements were performed by means of passive samplers. At 184 locations in three so-called ROM areas (southeast Friesland, the Gelder Valley and northeast Brabant) the measurements were performed in the period of February 1996 to January 1997. The OPS model was used along with emissions of different sources for calculating the concentrations. The emissions used differ from each other as far as the study area, the resolution and the underlying level of aggregation are concerned. The measured concentrations are 2 times higher than the calculated concentrations. This underestimation is about equal for all three study areas. Taking into account the uncertainty ranges in the calculations it can be stated that the calculations can account for a maximum of 60 to 65% of the measured concentrations. Based on comparative measurement studies it is unlikely that the difference between measured and calculated concentrations can be explained by a overestimation of the measured concentrations. If the remaining difference is to be explained by adjusting the emission levels in the mentioned areas, the present emissions have to be increased by 50 to 70%. The comparison of the measurements with the model calculations showed that the OPS model is capable of giving a good spatial representation of the measured concentrations when measurements and calculations were averaged per square 5x5 km. Based on emissions with a resolution of 5x5 km, about 80% of the spatial variation can be explained in this way. Within the 5x5 km squares large variations (up to a factor 10) of the depositions occur. Mainly stable and storage emission are responsible for this variations, because of the high contribution of these emissions to the total emission. For calculating concentrations and depositions on a ecosystem level emissions with more detail (e.g. 500x500 m and individual stable and storage emissions as a point source) will lead to more realistic emissions.
    • Karakteristieken van de bodems op de proefboerderij &quot;Kooyenburg&quot; te Rolde (Drenthe)

      Fraters B; van Vilsteren H (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1991-06-30)
      This work is part of a project to obtain field data for the calibration of a regional water quality model which describes the processes of pesticide transport to open water. This part should provide the necessary soil physical and physico-chemical characteristics of the experimental fields used to obtain pesticide data. These fields are part of the experimental farm "Kooyenburg". Characteristics studied are horizontal thickness and depth, and per (sub)horizontal organic matter content, texture, pH, bulk density, porosity and field moisture content. Results indicate that soils on the experimental farm are marked by a high degree of heterogeneity, especially with respect to the thickness of the illuvial horizontal and with respect to the occurrence and depth of the boulder clay. The organic matter content is an important model parameter. Determination of the organic matter content, especially of layers with low contents, could not be realized with enough accuracy, due to analytical problems.<br>
    • Kartografisch Handboek

      Bartels CJ; Veen AA van der; Ormeling FJ; Koop RO; ISC; UU/VK; LWD (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1994-06-30)
      The Cartographic Manual is a report that can serve as a guideline to map design and map production within RIVM. The report is intended for everyone in the organisation who is, in one way or another, involved in map making for the preparation of strategic reports like the National Environmental Balance and the National Environmental Outlook. It contains a discussion of some essential principles and technical skills with respect to map design. This is clarified with the use of example maps from recent RIVM publications. Furthermore, the report gives a view on the technical and organizational procedures of future map production at RIVM. The recommendations made in this report are aimed at a further optimization of the transfer and presentation of spatial information from RIVM to policy makers.