Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Effects of Dutch livestock production on human health and the environment
    Post, Pim M. ; Hogerwerf, Lenny ; Bokkers, Eddie A.M. ; Baumann, Bert ; Fischer, Paul ; Rutledge-Jonker, Susanna ; Hilderink, Henk ; Hollander, Anne ; Hoogsteen, Martine J.J. ; Liebman, Alex ; Mangen, Marie-Josée J. ; Manuel, Henk Jan ; Mughini-Gras, Lapo ; Poll, Ric van; Posthuma, Leo ; Pul, Addo van; Rutgers, Michiel ; Schmitt, Heike ; Steenbergen, Jim van; Sterk, Hendrika A.M. ; Verschoor, Anja ; Vries, Wilco de; Wallace, Robert G. ; Wichink Kruit, Roy ; Lebret, Erik ; Boer, Imke J.M. de - \ 2020
    Science of the Total Environment 737 (2020). - ISSN 0048-9697
    Animal production - Climate impact - Disability-adjusted life year (DALY) - Environmental impact - Livestock farming

    Observed multiple adverse effects of livestock production have led to increasing calls for more sustainable livestock production. Quantitative analysis of adverse effects, which can guide public debate and policy development in this area, is limited and generally scattered across environmental, human health, and other science domains. The aim of this study was to bring together and, where possible, quantify and aggregate the effects of national-scale livestock production on 17 impact categories, ranging from impacts of particulate matter, emerging infectious diseases and odor annoyance to airborne nitrogen deposition on terrestrial nature areas and greenhouse gas emissions. Effects were estimated and scaled to total Dutch livestock production, with system boundaries including feed production, manure management and transport, but excluding slaughtering, retail and consumption. Effects were expressed using eight indicators that directly express Impact in the sense of the Drivers-Pressures-State-Impact-Response framework, while the remaining 14 express Pressures or States. Results show that livestock production may contribute both positively and negatively to human health with a human disease burden (expressed in disability-adjusted life years) of up to 4% for three different health effects: those related to particulate matter, zoonoses, and occupational accidents. The contribution to environmental impact ranges from 2% for consumptive water use in the Netherlands to 95% for phosphorus transfer to soils, and extends beyond Dutch borders. While some aggregation across impact categories was possible, notably for burden of disease estimates, further aggregation of disparate indicators would require normative value judgement. Despite difficulty of aggregation, the assessment shows that impacts receive a different contribution of different animal sectors. While some of our results are country-specific, the overall approach is generic and can be adapted and tuned according to specific contexts and information needs in other regions, to allow informed decision making across a broad range of impact categories.

    Concentraties in bodemvocht en grondwater: Trends in ammonium en nitraat
    Vries, W. de; Kros, J. ; Wattel-Koekkoek, E.J.W. ; Pul, A. van - \ 2018
    V-focus 15 (2018)5. - ISSN 1574-1575 - p. 40 - 43.
    Ammoniak in het milieu: Trends bij korstmossen
    Herk, K. van; Kros, J. ; Vries, W. de; Pul, A. van - \ 2018
    V-focus 15 (2018)6. - ISSN 1574-1575 - p. 30 - 33.
    Improving Milk Quality in Smallholder Dairy Systems: Towards Realising Food Safety and Food Security in Kenya
    Nyokabi, Simon ; Oosting, S.J. ; Omedo Bebe, Bockline ; Bett, Bernard ; Lindahl, Johanna ; Boer, I.J.M. de - \ 2018
    In: Global food security and food safety: The role of universities. - Weikersheim : Margraf Publishers - ISBN 9783823617600 - p. 365 - 365.
    Smallholder dairy value chains provide high quality protein for consumers, and income and employment for farmers and dairy value chain actors in Kenya. Milk quality in the informal value chain, the primary market channel in Kenya is variable, often does not meet standards, undermines food security and food safety, and constitutes a constraint to longterm sustainability of the sector. An improvement in milk quality would enable Kenya to move towards realising sustainable food security as envisioned by the United Nations sustainable development goal 2. To achieve improved milk quality, there is need to focus on
    prevention of hazards (chemical, physical and microbial contaminants) notably, through implementation of existing but unenforced quality assurance systems in the value chain. This study was carried out in Nakuru, Nyandarua and Laikipia counties in Kenya using a mixed methods approach. A spatial framework for market quality guided the study and considered urban and peri-urban locations (PUL), mid- rural locations (MRL) and extreme rural locations (ERL). A questionnaire was administered to 652 smallholder farmers to elicit information on farm practices and knowledge relating to milk quality. 432 milk
    samples were collected in the formal and informal value chains. Analyses for composition, microbial contamination were undertaken. Observations were made across the value chains. Finally, key informant interviews were held to triangulate information. Findings revealed high microbial contamination in all three counties (E. coli 35.2%, Pseudomonas spp. 53.4, Staphylococcus spp. 2.5% and 2.3% positive for milk ring test (MRT). Microbial contamination was higher in MRL and PUL than in ERL. Composition revealed mean butterfat 3.58 %, protein3.53% and Solid not-fat 9.190%. Protein content was below average except in Nyandarua and in MRL when results were analysed according to the spatial framework and counties. Economic incentives encouraging farmers to improve milk quality were lacking. There was low knowledge of milk quality especially the importance of composition across all counties. Institutional capacity (under-staffing and
    lack of resources) constrained the implementation and enforcement of milk quality control systems. Observations revealed the use of non-food grade plastic containers and poor handling of milk by actors across the value chain.
    Concentraties en depositie : Trends in ammoniak en ammonium
    Pul, A. van; Wichink Kruit, R. ; Frumau, A. ; Kros, J. ; Vries, W. de - \ 2018
    V-focus 14 (2018)4. - ISSN 1574-1575 - p. 18 - 21.
    Dit artikel geeft de laatste stand van zaken aan de hand van een analyse van metingen in regenwater en lucht in de periode 1990-2015. We beschrijven de resultaten van deze belangrijkste meetreeksen gerelateerd aan ammoniak en vervolgens geven we aan welk algemeen beeld hieruit af te leiden valt.
    Effecten van het verzurings- en ammoniakbeleid
    Kros, H. ; Vries, W. de; Pul, A. van; Wattel-Koekkoek, E. ; Wichink Kruit, R. ; Herk, K. van; Frumau, A. - \ 2018
    V-focus 15 (2018)3. - ISSN 1574-1575 - p. 26 - 29.
    In dit artikel wordt een samenvattend overzicht gegeven van een reeks van drie artikelen die in aansluitende uitgaven van V-focus verschijnen. Hierbij is over de periode 1990-2015 gekeken naar de trends in emissie en depositie van ammoniak (te verschijnen in juli), de bijbehorende trends van ammonium en nitraat in bodemvocht en grondwater in natuurgebieden (te verschijnen in september) en trends in korstmossen (te verschijnen in november)
    A novel acetyl xylan esterase enabling complete deacetylation of substituted xylans
    Razeq, Fakhria M. ; Jurak, Edita ; Stogios, Peter J. ; Yan, Ruoyu ; Tenkanen, Maija ; Kabel, Mirjam A. ; Wang, Weijun ; Master, Emma R. - \ 2018
    Biotechnology for Biofuels 11 (2018)1. - ISSN 1754-6834
    Acetyl xylan esterase - Glucuronic acid - Polysaccharide utilization loci - SGNH hydrolase - Xylan - α-Glucuronidase
    Background: Acetylated 4-O-(methyl)glucuronoxylan (GX) is the main hemicellulose in deciduous hardwood, and comprises a β-(1→4)-linked xylopyranosyl (Xylp) backbone substituted by both acetyl groups and α-(1→2)-linked 4-O-methylglucopyranosyluronic acid (MeGlcpA). Whereas enzymes that target singly acetylated Xylp or doubly 2,3-O-acetyl-Xylp have been well characterized, those targeting (2-O-MeGlcpA)3-O-acetyl-Xylp structures in glucuronoxylan have remained elusive. Results: An unclassified carbohydrate esterase (FjoAcXE) was identified as a protein of unknown function from a polysaccharide utilization locus (PUL) otherwise comprising carbohydrate-active enzyme families known to target xylan. FjoAcXE was shown to efficiently release acetyl groups from internal (2-O-MeGlcpA)3-O-acetyl-Xylp structures, an activity that has been sought after but lacking in known carbohydrate esterases. FjoAcXE action boosted the activity of α-glucuronidases from families GH67 and GH115 by five and nine times, respectively. Moreover, FjoAcXE activity was not only restricted to GX, but also deacetylated (3-O-Araf)2-O-acetyl-Xylp of feruloylated xylooligomers, confirming the broad substrate range of this new carbohydrate esterase. Conclusion: This study reports the discovery and characterization of the novel carbohydrate esterase, FjoAcXE. In addition to cleaving singly acetylated Xylp, and doubly 2,3-O-acetyl-Xylp, FjoAcXE efficiently cleaves internal 3-O-acetyl-Xylp linkages in (2-O-MeGlcpA)3-O-acetyl-Xylp residues along with densely substituted and branched xylooligomers; activities that until now were missing from the arsenal of enzymes required for xylan conversion.
    Airborne Emissions from Livestock Farms and Exposure of Nearby Residents using an Atmospheric Dispersion Model
    Sterk, H.A.M. ; Swart, A.N. ; Leuken, J.P.G. van; Schijven, J.F. ; Aarnink, A.J.A. ; Wouters, I.M. ; Janse, I. ; Wichink Kruit, R.J. ; Pul, W.A.J. van - \ 2018
    In: ITM 2016: Air Pullution Modeling and its Application XXV. - Springer (Springer Proceedings in Complexity ) - ISBN 9783319576442 - p. 487 - 494.
    To estimate the exposure of local residents to substances emitted by livestock farms, we applied a dispersion model to calculate the air concentrations in the surroundings following from these emissions. At several livestock farms, indoor air measurements were performed to determine emission strengths, while ambient measurements were carried out to compare with model results. Measured substances were particulate matter (PM), endotoxins and micro-organisms. The dispersion model only simulated PM concentrations, which were used as a proxy to determine the dispersion concentrations of endotoxins and micro-organisms. For the living micro-organisms, the process of inactivation has to be taken into account. Here we describe the followed methodology and preliminary results.
    Effecten van landschapselementen op de ammoniakdepositie in Natura 2000- gebieden
    Kros, J. ; Gies, T.J.A. ; Voogd, J.C.H. ; Vries, Wilco de; Aben, Jan ; Pul, Addo - \ 2015
    Alterra, Wageningen-UR (Alterra-rapport 2689) - 37
    landschapselementen - landschap - ammoniak - depositie - overijssel - landscape elements - landscape - ammonia - deposition - overijssel
    Om het mogelijke effect van het aanbrengen van landschapselementen op de NHx (NH3 + NH4 +) depositie op Natura 2000-gebieden in te schatten, is door Alterra een aantal indicatieve berekeningen uitgevoerd voor de gehele provincie Overijssel. De berekeningen zijn uitgevoerd met het OPS-model van het RIVM. Het aanbrengen van een landschapselement van 50m breed rondom bedrijven, lijkt van de doorgerekende scenario’s het meestbelovend.
    Simulating emission of ammonia after liquid manure applicaton on arable land : Preliminary performance assessment of the Volt'air model for manure application conditions in the Netherlands
    Huijsmans, J.F.M. ; Holterman, H.J. ; Vermeulen, G.D. ; Stolk, A.J. ; Pul, W.A.J. van - \ 2014
    Wageningen : Wageningen UR - 42
    akkerbouw - rundveemest - ammoniakemissie - nederland - arable farming - cattle manure - ammonia emission - netherlands
    The high variability of the total ammonia emission after manure application on agricultural land in the Netherlands can be partly be linked to the application method, slurry characteristics and the meteorological conditions by statistical analysis of the experimental results.
    Balans van de leefomgeving 2014 deel 4 : landbouw en voedsel
    Grinsven, H. van; Eerdt, M. van; Westhoek, H. ; Hooijboer, A. ; Buis, E. ; Pul, A. van; Hilderink, H. ; Schroder, J.J. ; Verdoes, N. ; Voswinkel, T. ; Nijdam, D. ; Oorschot, M. van; Tiktak, A. ; Schijndel, M. ; Sluis, S. van der; Reudink, M. ; Rood, T. - \ 2014
    Den Haag : Planbureau voor de Leefomgeving - 33
    milieueffect - landbouw - voedselproductie - duurzaamheid (sustainability) - voeding en gezondheid - voedselconsumptie - veehouderij - landbouwproductie - environmental impact - agriculture - food production - sustainability - nutrition and health - food consumption - livestock farming - agricultural production
    In dit rapport analyseert het PBL de effecten van de landbouw op de leefomgeving, evenals, in bredere zin, de voortgang van de verduurzaming van het voedselsysteem. We evalueren bovendien de effectiviteit van het Nederlandse overheidsbeleid als het erom gaat die effecten te verminderen. We beschrijven de belangrijkste ontwikkelingen op dit gebied in de afgelopen twee jaar, en bouwen daarbij voort op de analyse van de verduurzaming van het voedselsysteem in de vorige Balans van de Leefomgeving en het rapport De macht van het menu (PBL 2013a) maar leggen meer nadruk op de effecten voor de fysieke leefomgeving binnen Nederland.
    Ammonia emission from standing crops and crop residues : contribution to total ammonia emission in the Netherlands
    Ruijter, F.J. de; Huijsmans, J.F.M. ; Zanten, M.C. ; Asman, W.A.H. ; Pul, W.A.J. van - \ 2013
    Wageningen : Plant Research International (Report / Plant Research International 535) - 82
    gewassen - oogstresten - emissiereductie - ammoniakemissie - crops - crop residues - emission reduction - ammonia emission
    Ammonia emission from standing crops and crop residues : contribution to total ammonia emission in the Netherlands
    Protocol gebruiksvoorschriften dierlijke mest, versie 1.0
    Velthof, G.L. ; Bussink, W. ; Dijk, W. van; Groenendijk, P. ; Huijsmans, J.F.M. ; Pul, W.A.J. van; Schroder, J.J. ; Vellinga, Th.V. ; Oenema, O. - \ 2013
    Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-rapport 120) - 86
    dierlijke meststoffen - bemesting - verontreinigingsbeheersing - wetgeving - kwaliteitsnormen - akkerbouw - graslanden - maïs - Nederland - animal manures - fertilizer application - pollution control - legislation - quality standards - arable farming - grasslands - maize - Netherlands
    Het Besluit Gebruik Meststoffen schrijft voor dat dierlijke mest op emissiearme wijze wordt toegediend. Dit Besluit bepaalt daarnaast in welke periode van het jaar dierlijke mest op het land mag worden gebracht. Deze voorschriften hebben tot doel om de emissies van stikstof en fosfaat naar het milieu te beperken. In de laatste jaren zijn producten uit mestverwerking beschikbaar gekomen. Deze nieuwe mestsoorten kunnen afwijkende emissie-eigenschappen hebben, zodat er aanleiding kan zijn om andere eisen te stellen aan de wijze waarop en de periode waarin het product wordt toegediend. Het ministerie van Economische Zaken heeft aan de Commissie van Deskundigen Meststoffenwet (CDM) gevraagd om een protocol op te stellen, dat in staat stelt te beoordelen welk risico de toepassing van mestsoorten, toedieningstechnieken en toedieningstijdstippen heeft op uitspoeling van stikstof en fosfaat naar grond- en oppervlaktewater en op de emissies van ammoniak en lachgas naar de atmosfeer. In dit rapport wordt het protocol beschreven. Met het protocol wordt een oordeel gegeven van het risico op emissies ten opzichte van referentiemeststoffen, -toedieningstijdstippen en - toedieningstechnieken. Met de resultaten van de beoordelingen met dit protocol moet het ministerie een beleidsafweging kunnen maken met betrekking tot gebruiksvoorschriften voor dierlijke mest en producten daarvan.
    Two instruments based on differential optical absorption spectroscopy (DOAS) to measure accurate ammonia concentrations in the atmosphere
    Volten, H. ; Bergwerff, J.B. ; Haaima, M. ; Lolkema, D.E. ; Berkhout, A.J.C. ; Hoff, G.R. ; Potma, C.J.M. ; Wichink Kruit, R.J. ; Pul, W.A.J. van; Swart, D.P.J. - \ 2012
    Atmospheric Measurement Techniques 5 (2012)2. - ISSN 1867-1381 - p. 413 - 427.
    cross-sections - herzberg continuum - region - ultraviolet - nm - temperature - spectrum - fluxes - so2 - nh3
    We present two Differential Optical Absorption Spectroscopy (DOAS) instruments built at RIVM: the RIVM DOAS and the miniDOAS. Both instruments provide virtually interference-free measurements of NH3 concentrations in the atmosphere, since they measure over an open path, without suffering from inlet problems or interference problems by ammonium aerosols dissociating on tubes or filters. They measure concentrations up to at least 200 mu g m(-3), have a fast response, low maintenance demands, and a high up-time. The RIVM DOAS has a high accuracy of typically 0.15 mu g m(-3) for ammonia for 5-min averages and over a total light path of 100 m. The miniDOAS has been developed for application in measurement networks such as the Dutch National Air Quality Monitoring Network (LML). Compared to the RIVM DOAS it has a similar accuracy, but is significantly reduced in size, costs, and handling complexity. The RIVM DOAS and miniDOAS results showed excellent agreement (R-2 = 0.996) during a field measurement campaign in Vredepeel, the Netherlands. This measurement site is located in an agricultural area and is characterized by highly variable, but on average high ammonia concentrations in the air. The RIVM-DOAS and miniDOAS results were compared to the results of the AMOR instrument, a continuous-flow wet denuder system, which is currently used in the LML. Averaged over longer time spans of typically a day, the (mini) DOAS and AMOR results agree reasonably well, although an off-set of the AMOR values compared to the (mini) DOAS results exists. On short time scales, the (mini) DOAS shows a faster response and does not show the memory effects due to inlet tubing and transport of absorption fluids encountered by the AMOR. Due to its high accuracy, high uptime, low maintenance and its open path, the (mini) DOAS shows a good potential for flux measurements by using two (or more) systems in a gradient set-up and applying the aerodynamic gradient technique.
    Transcriptome analysis of a long-lived natural Drosophila variant: a prominent role of stress- and reproduction-genes in lifespan extension
    Doroszuk, A. ; Jonker, M.J. ; Pul, N. ; Breit, T.M. ; Zwaan, B.J. - \ 2012
    BMC Genomics 13 (2012). - ISSN 1471-2164
    genome-wide - starvation resistance - expression patterns - caloric restriction - dietary restriction - c-elegans - caenorhabditis-elegans - laboratory selection - oxidative stress - immune-response
    Background While studying long-lived mutants has advanced our understanding of the processes involved in ageing, the mechanisms underlying natural variation in lifespan and ageing rate remain largely unknown. Here, we characterise genome-wide expression patterns of a long-lived, natural variant of Drosophila melanogaster resulting from selection for starvation resistance (SR) and compare it with normal-lived control flies (C). We do this at two time points representing middle age (90% survival) and old age (10% survival) respectively, in three adult diets (malnutrition, optimal food, and overfeeding). Results We found profound differences between Drosophila lines in their age-related expression. Most of the age-associated changes in normal-lived flies were abrogated in long-lived Drosophila. The stress-related genes, including those involved in proteolysis and cytochrome P450, were generally higher expressed in SR flies and showed a smaller increase in expression with age compared to C flies. The genes involved in reproduction showed a lower expression in middle-aged SR than in C flies and, unlike C flies, a lack of their downregulation with age. Further, we found that malnutrition strongly affected age-associated transcript patterns overriding the differences between the lines. However, under less stressful dietary conditions, line and diet affected age-dependent expression similarly. Finally, we present lists of candidate markers of ageing and lifespan extension. Conclusions Our study unveils transcriptional changes associated with lifespan extension in SR Drosophila. The results suggest that natural genetic variation for SR and lifespan can operate through similar transcriptional mechanisms as those of dietary restriction and life-extending mutations. Keywords: Ageing; Gene expression; Microarray; Drosophila melanogaster; Natural variation; Diet
    Changed gene expression for candidate ageing genes in long-lived Bicyclus anynana butterflies
    Pijpe, J. ; Pul, N. ; Duijn, S. van; Brakefield, P.M. ; Zwaan, B.J. - \ 2011
    Experimental Gerontology 46 (2011)6. - ISSN 0531-5565 - p. 426 - 434.
    quantitative trait loci - extend life-span - drosophila-melanogaster - oxidative damage - caenorhabditis-elegans - starvation resistance - adaptive evolution - stress resistance - natural variation - longevity
    Candidate genes for the regulation of lifespan have emerged from studies that use mutants and genetically manipulated model organisms. However, it is rarely addressed whether these genes contribute to lifespan variation in populations of these species that capture natural standing genetic variation. Here, we explore expression variation in three candidate ageing genes, Indy, sod2, and catalase, in Bicyclus anynana, a butterfly with well understood ecology. We used lines established from natural populations and artificially selected for increased adult starvation resistance. They show a considerable increase in adult lifespan under both starvation and optimal food conditions. We measured adult butterflies of various ages, under a range of optimal and starvation diets, from two selected populations and one unselected control population. In all lines, Indy and catalase are up-regulated in response to starvation while this is not evident for sod2. Under starvation, Indy and catalase are up-regulated in, while this is not evident for sod2. Under optimal food conditions, Indy is down-regulated at a later age, with Indy expression showing relatively high inter-individual variation. We find differences between the selected lines and the unselected line. Under starvation conditions, expression is higher for catalase in one, and for sod2 in both selected lines. Importantly, sod2 expression is also higher in the selected populations under optimal food conditions. We conclude that sod2, but not Indy, is involved in the response to artificial selection for increased starvation resistance. The role of catalase is less clear because of the differences between the two selected lines. Moreover, sod2 appears to be a candidate gene that underpins the genetic correlation between starvation resistance and longevity. Our study indicates that some, but not all, genes identified through mutant screens in other organisms may underpin standing genetic variation for ageing-related traits in stocks of Bicyclus butterflies established from natural populations. Clearly, this needs to be investigated in other organisms as well, especially in the organisms to which mutants screens were applied. This information will narrow down the list of genes that underpin variation in lifespan and ageing in extant populations of organisms, and which may serve as candidate genes in humans
    H-NS-mediated repression of CRISPR-based immunity in Escherichia coli K12 can be relieved by the transcription activator LeuO
    Westra, E.R. ; Pul, Ü. ; Heidrich, N. ; Jore, M.M. ; Lundgren, N.M.J. ; Stratmann, T. ; Wurm, R. ; Raine, A. ; Mescher, M. ; Heereveld, L. van; Mastop, M. ; Wagner, E.G.H. ; Schnetz, K. ; Oost, J. van der; Wagner, R. ; Brouns, S.J.J. - \ 2010
    Molecular Microbiology 77 (2010)6. - ISSN 0950-382X - p. 1380 - 1393.
    coli k-12 - salmonella-typhimurium - gene-expression - regulator leuo - foreign dna - in-vivo - protein - bacteria - repeats - rna
    The recently discovered prokaryotic CRISPR/Cas defence system provides immunity against viral infections and plasmid conjugation. It has been demonstrated that in Escherichia coli transcription of the Cascade genes (casABCDE) and to some extent the CRISPR array is repressed by heat-stable nucleoid-structuring (H-NS) protein, a global transcriptional repressor. Here we elaborate on the control of the E. coli CRISPR/Cas system, and study the effect on CRISPR-based anti-viral immunity. Transformation of wild-type E. coli K12 with CRISPR spacers that are complementary to phage Lambda does not lead to detectable protection against Lambda infection. However, when an H-NS mutant of E. coli K12 is transformed with the same anti-Lambda CRISPR, this does result in reduced sensitivity to phage infection. In addition, it is demonstrated that LeuO, a LysR-type transcription factor, binds to two sites flanking the casA promoter and the H-NS nucleation site, resulting in derepression of casABCDE12 transcription. Overexpression of LeuO in E. coli K12 containing an anti-Lambda CRISPR leads to an enhanced protection against phage infection. This study demonstrates that in E. coli H-NS and LeuO are antagonistic regulators of CRISPR-based immunity
    Surface-atmosphere exchange of ammonia : measurements and modeling over non-fertilized grassland in the Netherlands
    Wichink Kruit, R.J. - \ 2010
    Wageningen University. Promotor(en): Bert Holtslag; Maarten Krol, co-promotor(en): W.A.J. van Pul. - [S.l. : S.n. - ISBN 9789085856429 - 175
    graslanden - landbouw - ammoniak - emissie - kringlopen - stikstofkringloop - modellen - nederland - ammoniakemissie - grasslands - agriculture - ammonia - emission - cycling - nitrogen cycle - models - netherlands - ammonia emission
    In dit proefschrift wordt de oppervlakte-atmosfeer uitwisseling van ammoniak boven agrarisch grasland in Nederland bestudeerd. De belangrijkste doelstellingen van dit proefschrift zijn om een beter begrip van het oppervlakte-atmosfeer uitwisselingsproces van ammoniak te krijgen, vooral boven agrarische grasland in Nederland, en om de modelbeschrijving van het oppervlakte-atmosfeer uitwisselingsproces van ammoniak te verbeteren.
    Modeling the surface-atmosphere exchange of ammonia
    Wichink Kruit, R.J. ; Pul, W.A.J. van; Slauter, F.J. ; Broek, M. van den; Nemitz, E. ; Sutton, M.A. ; Krol, M.C. ; Holtslag, A.A.M. - \ 2010
    Atmospheric Environment 44 (2010)7. - ISSN 1352-2310 - p. 945 - 957.
    intensively managed grassland - nh3 deposition processes - oilseed rape plants - compensation point - dry deposition - seminatural vegetation - agricultural grassland - gradient measurements - apoplastic nh4+ - lolium-perenne
    New parameterizations for surfaceeatmosphere exchange of ammonia are presented for application in atmospheric transport models and compared with parameterizations of the literature. The new parameterizations are based on a combination of the results of three years of ammonia flux measurements over a grassland canopy (dominated by Lolium perenne and Poa trivialis) near Wageningen, the Netherlands and existing parameterizations from literature. First, a model for the surfaceeatmosphere exchange of ammonia that includes the concentration at the external leaf surface is derived and validated. Second, a parameterization for the stomatal compensation point (expressed as Gs, the ratio of [NH4+]/[H+] in the leaf apoplast) that accounts for the observed seasonal variation is derived from the measurements. The new, temperature-dependent Gs describes the observed seasonal behavior very well. It is noted, however, that senescence of plants and field management practices will also influence the seasonal variation of Gs on a shorter timescale. Finally, a relation that links Gs to the atmospheric pollution level of the location through the ‘long-term’ NH3 concentration in the air is proposed.
    Linking nitrogen deposition to nitrate concentrations in groundwater below nature areas : modelling approach and data requirements
    Bonten, L.T.C. ; Mol-Dijkstra, J.P. ; Wieggers, H.J.J. ; Vries, W. de; Pul, W.A.J. van; Hoek, K.W. van den - \ 2009
    Wageningen : Alterra (Alterra-rapport 1881) - 41
    natuurreservaten - grondwater - grondwaterverontreiniging - nitraat - stikstof - depositie - wiskundige modellen - gegevens verzamelen - natuur - nature reserves - groundwater - groundwater pollution - nitrate - nitrogen - deposition - mathematical models - data collection - nature
    This study determines the most suitable model and required model improvements to link atmospheric deposition of nitrogen and other elements in the Netherlands to measurements of nitrogen and other elements in the upper groundwater. The deterministic model SMARTml was found to be the most suitable model. The model requires an improved C&N modeling, improved forest growth modeling, linking forest growth to hydrology and an explicit dispersion calculation. A large number of independent data are available for validation of the improved model. Application of the model to sites of the ‘National monitoring network on nitrate concentrations in the upper groundwater under nature areas’ requires assumptions on soil properties, hydrology, deposition of base cations and chloride.
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