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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Combining food-based dietary recommendations using Optifood with zinc-fortified water potentially improves nutrient adequacy among 4- to 6-year-old children in Kisumu West district, Kenya
Kujinga, Prosper ; Borgonjen-van den Berg, Karin J. ; Superchi, Cecilia ; Hove, Hermine J. ten; Onyango, Elizabeth Opiyo ; Andang'o, Pauline ; Galetti, Valeria ; Zimmerman, Michael B. ; Moretti, Diego ; Brouwer, Inge D. - \ 2018
Maternal and Child Nutrition 14 (2018)2. - ISSN 1740-8695
children - diets - Optifood - water - zinc
Children in developing countries often face multiple micronutrient deficiencies. Introduction of zinc-fortified water can increase zinc intake, but additional recommendations are required to address overall diet nutrient adequacy. We developed and tested food-based recommendations (FBRs) that included zinc-fortified water for children aged between 4 and 6 years from rural Kenya to achieve the best possible nutrient adequacy. Dietary intakes of 60 children aged 4–6 years, from Kisumu West district, Kenya, were assessed using a quantitative multipass 24-hr recall. Linear programming model parameters were derived, including a list of foods consumed, median serving sizes, and distribution of frequency of consumption. By using the Optifood linear programming tool, we developed FBRs for diets including zinc-fortified water. FBRs with nutrient levels achieving ≥70% recommended nutrient intake (RNI) of the World Health Organization/Food and Agriculture Organization of the United Nations RNI for most of the 12 considered nutrients were selected as the final recommendations for the children. With no FBRs and no zinc-fortified water, percent RNI coverage range was between 40% and 76% for zinc, improving to 66–101% after introduction of zinc-fortified water. The final set of FBRs achieved nutrient adequacy for all nutrients except for vitamin A (25% RNI) and folate (68% RNI). Introduction of zinc-fortified water combined with FBRs will likely improve the nutrient adequacy of diets consumed by children in Kenya but needs to be complemented with alternative interventions to ensure dietary adequacy.
Biodiversity and climate determine the functioning of Neotropical forests
Poorter, L. ; Sande, M.T. van der; Arets, E.J.M.M. ; Ascarrunz, N. ; Enquist, B.J. ; Finegan, B. ; Licona, J.C. ; Martinez-Ramos, M. ; Mazzei, L. ; Meave, J. ; Munoz, R. ; Nytch, C.J. ; Oliveira, A.A. de; Perez-Garcia, E.A. ; Prado-Junior, J.A. ; Rodriguez-Velazquez, J. ; Ruschel, A.R. ; Salgado Negret, B. ; Schiavini, I. ; Swenson, N.G. ; Tenorio, E.A. ; Thompson, J. ; Toledo, M. ; Uriarte, M. ; Hout, P. van der; Zimmerman, J.K. ; Pena Claros, M. - \ 2017
biodiversity - biomass - carbon - ecosystem functioning - forest dynamics - productivity - soil fertility - tropical forest - water
Tropical forests account for a quarter of the global carbon storage and a third of the terrestrial productivity. Few studies have teased apart the relative importance of environmental factors and forest attributes for ecosystem functioning, especially for the tropics. This study aims to relate aboveground biomass (AGB), biomass dynamics (i.e., net biomass productivity and its underlying demographic drivers: biomass recruitment, growth and mortality) to forest attributes (tree diversity, community-mean traits, and stand basal area) and environmental conditions (water availability, soil fertility and disturbance). We used data from 26 sites, 201 one-ha plots and >92,000 trees distributed across the Neotropics. We quantified for each site water availability and soil total exchangeable bases and for each plot three key community-weighted mean functional traits that are important for biomass stocks and productivity. We used structural equation models to test the hypothesis that all drivers have independent, positive effects on biomass stocks and dynamics. Of the relationships analysed, vegetation attributes were more frequently significantly associated with biomass stocks and dynamics than environmental conditions (in 67% versus 33% of the relationships). High climatic water availability increased biomass growth and stocks, light disturbance increased biomass growth, and soil bases had no effect. Rarefied tree species richness had consistent positive relationships with biomass stocks and dynamics, probably because of niche complementarity, but was not related to net biomass productivity. Community-mean traits were good predictors of biomass stocks and dynamics. Water availability has a strong positive effect on biomass stocks and growth, and a future predicted increase in (atmospheric) drought might, therefore, potentially reduce carbon storage. Forest attributes – including species diversity and community-weighted mean traits – have independent and important relationships with AGB stocks, dynamics, and ecosystem functioning, not only in relatively simple temperate systems, but also in structurally complex hyper-diverse tropical forests.
De energiesector als lichtend of verblindend voorbeeld?
Giezen, M. ; Brouwer, Stijn ; Roest, Kees ; Vliet, B.J.M. van - \ 2017
H2O online (2017). - 6 p.
energie - water - hernieuwbare energie - systemen - economie - energy - renewable energy - systems - economics
De energiesector wordt in de watersector veelvuldig genoemd als voorbeeld voor de transitie richting een circulaire economie. In hoeverre werkt dit verhelderend of juist verblindend? In deze literatuurstudie laten de auteurs hun licht schijnen op de energiesector als voorbeeld wanneer het gaat om de introductie van nieuwe decentrale technieken. Vanuit zowel een technologisch, economisch, sociaal-cultureel als een institutioneel perspectief brengen de auteurs de contextuele systeemveranderingen die van invloed kunnen zijn op toepassing van decentrale technieken in kaart. Hiermee worden de overeenkomsten en verschillen tussen energie- en watersectoren helder en ontstaat ruimte voor relativering en nuance.
Becoming an Engineer or a Lady Engineer : Exploring Professional Performance and Masculinity in Nepal’s Department of Irrigation
Liebrand, Janwillem ; Udas, Pranita Bhushan - \ 2017
Engineering Studies 9 (2017)2. - ISSN 1937-8629 - p. 120 - 139.
Engineering - gender - irrigation - masculinities - Nepal - water
In this article, using the Department of Irrigation in Nepal as a case study, we argue that professional performance in irrigation engineering and water resources development is gendered and normalised as ‘masculine’. In Nepal, the masculinity of professional performance in irrigation engineering is located in intersections of gender, class, caste, ethnicity, sexuality, nationality and disciplinary education, and hinders especially female engineers to perform as a ‘normal’ engineer. Our analysis is based on interviews with male and female engineers in the department, documentation research, and ethnographic observations in the period 2005–2011. Our study suggests that professional performances and engineering identities in the organisation have always been tied to performances of masculinity. This implies that career prospects in the Nepalese irrigation department for female engineers remain grim; because for them to succeed and belong, they have to reconcile the near incommensurable: a performance of a ‘lady engineer’ with that of a ‘normal’ engineer.
Monitoring Groningen Sea Ports : non-indigenous species and risks from ballast water in Eemshaven and Delfzijl
Slijkerman, D.M.E. ; Glorius, S.T. ; Gittenberger, A. ; Weide, B.E. van der; Bos, O.G. ; Rensing, M. ; Groot, G.A. de - \ 2017
Den Helder : Wageningen Marine Research (Wageningen Marine Research rapport C045/17 A) - 81
havens - mariene gebieden - geïntroduceerde soorten - ballast - water - mariene ecologie - harbours - marine areas - introduced species - marine ecology
Evaluating rainwater harvesting systems in arid and semi-arid regions
Ammar, Adham Ali - \ 2017
University. Promotor(en): Coen Ritsema, co-promotor(en): Michel Riksen; M. Quessar. - Wageningen : Wageningen University - ISBN 9789463431460 - 207
water harvesting - rain - water - arid zones - semiarid zones - geographical information systems - water management - climatic change - tunisia - iraq - regenwateropvang - regen - aride klimaatzones - semi-aride klimaatzones - geografische informatiesystemen - waterbeheer - klimaatverandering - tunesië - irak

Rainwater harvesting (RWH) is an ancient traditional technology practised in many parts of the world, especially in arid and semi-arid regions (ASARs). ASARs represent 40% of the earth’s land surface and are characterised by low average annual rainfall and uneven temporal and spatial distributions of that rainfall. In these regions an efficient use of the limited amount of rainfall available is important, e.g. by collecting and using surface runoff (water harvesting). Lately, access to water for agriculture and domestic use has become worse because of increasing population, higher levels of human activity and the impacts of climate change. The inhabitants of ASARs have developed several RWH techniques to increase the water availability, thus coping with water shortages. RWH is an important mitigation strategy to the impact of climate change on water availability in ASARs.

Four main methodologies of site selection were categorised, ranging from those based only on biophysical criteria to more integrated approaches that include socioeconomic criteria. Our analysis suggests that the integration of multi-criteria analysis (MCA) with a geographic information system (GIS) is the most advanced approach. It offers high potential in data-poor regions; GIS-based hydrological modelling is always recommended for data-rich regions.

The potential for RWH in wadi Horan (western desert of Iraq) was identified using a GIS-based suitability model. The method for selecting suitable sites for RWH was then further developed into an evaluation and decision support tool for assessing the overall performance of existing RWH systems by integrating engineering, biophysical and socioeconomic criteria using MCA supported by GIS. It was tested in the wadi Oum Zessar in southeastern Tunisia.

A simple but generally applicable water harvesting model (WHCatch) was developed to investigate and optimise the performance of the RWH systems under various scenarios of design and management, It was tested in wadi Oum Zessar. The advantages of simulating long-term water balances at the sub-catchment level for improving our understanding of hydrological processes in an RWH system are emphasised. Several solutions for optimising RWH performance in various scenarios are provided.

Finally, the impact of climate change on existing RWH systems in the Oum Zessar watershed under current and future scenarios of climate was investigated. The downscaled maximum and minimum temperatures clearly indicated an increasing trend in the mean monthly temperature and the generated precipitation tended to decrease in the future. It was shown that the combination of changing the flow direction and the spillway height had a large impact on the performance of the RWH systems under current and future conditions. Water management and structural design at the sub-catchment level plays a more important role than climate change in the performance of RWH.

Temperature in water and sediment in the pesticide model TOXSWA : implementation report
Beltman, W.H.J. ; Adriaanse, P.I. ; Jacobs, C.M.J. ; Mulder, H.M. - \ 2017
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research report 2794) - 67
pesticides - water - temperature - models - sediment - surface water - pesticiden - temperatuur - modellen - oppervlaktewater
TOXSWA simuleert het gedrag van stoffen in oppervlaktewater om blootstellingsconcentratie te berekenen voor organismen die in water of sediment leven, als onderdeel van de aquatische risicobeoordeling van gewasbeschermingsmiddelen (GBM). Het vernieuwde concept voor de beschrijving van de temperatuur in het TOXSWA model werd getest aan de hand van een bestaande implementatie van het 1D bulk model.
Bodemhydrofysische gegevens in BRO en BIS : update 2016
Bakker, G. ; Heinen, M. ; Wesseling, J.G. ; Groot, W.J.M. de; Assinck, F.B.T. ; Hummelink, E.W.J. - \ 2017
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2789) - 77
bodemfysica - hydrologie - water - bodem - soil physics - hydrology - soil
Dynamics of rainwater lenses on upward seeping saline groundwater
Eeman, Sara - \ 2017
University. Promotor(en): Sjoerd van der Zee, co-promotor(en): Toon Leijnse. - Wageningen : Wageningen University - ISBN 9789462579330 - 158
seepage - rain - water - groundwater - saline water - vegetation - kwel - regen - grondwater - zout water - vegetatie

Fresh water is generally a limited resource in coastal areas which are often densely populated. In low-lying areas, groundwater is mostly saline and both agriculture and freshwater nature depend on a thin lens of rainwater that is formed by precipitation surplus on top of saline, upward seeping groundwater. Understanding the dynamics of such lenses is vital for sustainable food production and development of natural vegetation and biodiversity under changing conditions like sea level rise and climate change. The thickness of the mixing zone between the fresh and saline water is substantial and characteristics of this mixing zone cannot be neglected. In this thesis we have studied the behaviour of these thin rainwater lenses and their mixing zones.

To study the basic relations of such a system, we considered the development of a rainwater lens, starting from initially saline conditions using a numerical model. The ratio of seepage over precipitation, density difference and to a lesser extent the geometry of the flow domain, significantly influence the thickness of the lens and mixing zone. The thickness of the mixing zone is also significantly influenced by dispersion (as the lens grows), diffusion (at steady state) and distance from a drain (caused by convergence). Field observations show that geological layering influences these processes importantly and that head differences often overrule the effects of density difference. Groundwater salinity is furthermore influenced by re-mixing of soil- and rainwater, dual porosity and preferential flow. If there is significant seepage, the thickness of a lens can be estimated by an analytical solution.

The effects of weather and climate variations were numerically studied using sinusoidal and actual net precipitation patterns. The average lens thickness is hardly influenced by weather fluctuations and we can relate minimum and maximum lens thickness to this average thickness. The thickness of the mixing zone can be derived from the “travelled distance” from its center: thickness increases with increasing vertical movement due to alternating precipitation and evaporation. Field observations confirm this, but show concentration of dynamics in the top of the lens. This is not contradictory since the mixing zone for the studied site starts very near the ground water table, so indeed the mixing zone thickness is influenced by precipitation events. Convolution theory can be used to determine the impulse-response function for a thin lens which enables derivation of the delay and amplitude of a lens reaction to changes in climate.

The cation exchange process was investigated using a numerical model based on field data. On the short term, the process is characterized by the salt-shock caused by the large difference in concentration between rainwater and seepage water. The pore water quality changes quickly from saline to relatively fresh and from sodium and magnesium dominated to calcium dominated. On the long term, changes of the soil complex occur. This is a process of several centuries (even for the shallow systems studied), since the amount of cations in the fresh solution is very small compared to the amount of cations adsorbed to the soil. Initially, both calcium and magnesium in the sorption complex increase and later magnesium is outcompeted by calcium. The net flux downward has a much larger effect on the mixing process than short-term variations and the influence of tile drainage. Although the main flow component is horizontal, the water quality and soil complex are only influenced by the vertical flow that causes mixing of water with different composition. Comparison of the numerical model with field data from both study sites in Zeeland confirm our results and show that equilibrium has not yet been reached.

Influence of saline groundwater on vegetation development has been assessed simulating combinations of different vegetation types, soil characteristics and groundwater levels and –salinities for two different climates. We assessed the relative importance of these parameters on the fresh water availability and stress experienced by vegetation and put this in perspective of stress due to drought and lack of oxygen. Soil type and climate are shown to be the most important parameters. Salinity stress is substantial, but small compared to stress caused by lack of oxygen and drought. For areas with groundwater with limited salinity, salt tolerance may be a parameter that can be used to improve sustainability of agriculture. Where groundwater is more saline, soil and ground water management are the most effective tools.

Towards Water Smart Cities : climate adaptation is a huge opportunity to improve the quality of life in cities
Hattum, Tim ; Blauw, Maaike ; Bergen Jensen, Marina ; Bruin, Karianne de - \ 2016
Wageningen : Wageningen University & Research (Wageningen Environmental Research rapport 2787) - 60
water - waterbeheer - stedelijke gebieden - steden - klimaatverandering - klimaatadaptatie - water management - urban areas - towns - climatic change - climate adaptation
Pharmaceutical removal from water with iron- or manganese-based technologies : A review
Liu, Wenbo ; Sutton, Nora B. ; Rijnaarts, Huub H.M. ; Langenhoff, Alette A.M. - \ 2016
Critical Reviews in Environmental Science and Technology 46 (2016)19-20. - ISSN 1064-3389 - p. 1584 - 1621.
Biologically-related removal - chemical removal - iron- or manganese-based technology - pharmaceutical removal - physico-chemical removal - water
Pharmaceuticals are detected at trace levels in waters. Their adverse effects on aquatic ecosystems and human health demand novel pharmaceutical removal technologies for treating wastewater effluents. Iron (Fe) or manganese (Mn) may play important roles in these new technologies since these metals are abundantly available at low costs and are known to contribute to organic conversions via physico-chemical, chemical, and biologically related processes. Few reviews describe and discuss Fe- or Mn-based technologies for the purpose to remove pharmaceuticals from water. Therefore, we review the current literature sorted into the three removal mechanisms, that is., through physico-chemical, chemical, and biological processes. The principals, performance, and influential parameters of these three types of technologies are described. Current and potential applications of these technologies are critically evaluated in order to identify advantages and challenges. In addition, the Fe- or Mn-based technologies which are currently not used but promising to further develop to remove pharmaceuticals cost efficiently are proposed.
Kansenkaarten voor duurzaam benutten Natuurlijk Kapitaal
Knegt, B. de; Hoek, D.C.J. van der; Veerkamp, C.J. ; Woltjer, I. ; Aa, N.G.F.M. van der; Boekel, E.M.P.M. van; Diederiks, J.F.H.A. ; Goosen, H. ; Koekoek, A. ; Lesschen, J.P. ; Staritsky, I.G. ; Vries, F. de; Hendriks, C.M.A. - \ 2016
Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-technical report 75) - 122
ecosysteemdiensten - natuur - water - drinkwater - hoogwaterbeheersing - landbouw - nederland - ecosystem services - nature - drinking water - flood control - agriculture - netherlands
Local projects conducted within the framework of the Natural Capital Netherlands (NKN) programmeidentified various opportunities for mutual improvement of natural capital and the economy. In a follow-upstudy we investigated whether the insights gained also apply to other parts of the Netherlands. Which areasoffer the best opportunities? What measures are needed in these areas to actually capitalise on theseopportunities, and who are the relevant stakeholders? To address these questions, the local opportunitiesidentified in the NKN projects were explored at the national level, using ‘opportunity maps’. The three localprojects are: Greening the Common Agricultural Policy, Clean Water and Delta Programme
Modeling the coupled exchange of water and CO2 over croplands
Combe, Marie - \ 2016
University. Promotor(en): Wouter Peters; Maarten Krol, co-promotor(en): Jordi Vila-Guerau de Arellano. - Wageningen : Wageningen University - ISBN 9789462579255 - 152
carbon cycle - carbon dioxide - modeling - water - energy exchange - crop yield - grain crops - atmosphere - koolstofcyclus - kooldioxide - modelleren - energie-uitwisseling - gewasopbrengst - graangewassen - atmosfeer

Croplands are a managed type of vegetation, with a carbon storage that is highly optimized for food production. For instance, their sowing dates are chosen by the farmers, their genetic potential is bred for high grain yields, and their on-field competition with other species is reduced to the minimum. As a result of human intervention, croplands are a major land cover type (roughly one fifth of the land area over Europe) and they experience a short growing season during which they exchange carbon and water intensively with the atmosphere. Their growth significantly affects the seasonal amplitude of CO2 mole fractions over the globe, interact with extreme weather events such as droughts and heat waves, and impact surface hydrology due to their water consumption. However, and in spite of their relevance, terrestrial biosphere models used in carbon cycle and atmospheric research often assume the phenology of croplands to be similar to the one of grasslands, and they also ignore the impact of crop management. This oversimplification is the motivation for this thesis. We focus on understanding and modeling the key surface and atmospheric processes that shape the cropland water and CO2 exchange, and the resulting impact on the CO2 mole fractions of the atmosphere overhead. We study these processes from the daily to the seasonal scale, for croplands of the mid-latitudes. In the end, we come with recommendations and a new modeling framework to represent the cropland CO2 and water exchange in the Earth System, weather and climate models.

Water-binding of protein particles
Peters, J.P.C.M. - \ 2016
University. Promotor(en): Atze Jan van der Goot; Remko Boom. - Wageningen : Wageningen University - ISBN 9789462578623 - 198 p.
whey protein - proteins - particles - water binding capacity - water - nuclear magnetic resonance - wei-eiwit - eiwitten - deeltjes - waterbindend vermogen - kernmagnetische resonantie

As overweight and obesity become more prevalent in society, the demand for food products that can help maintain body weight increases. One way to make such products is by decreasing the protein and fat content through increasing the water content. This thesis describes the potential of protein microparticles (MPs) to bind ≥ 90% w/w water tightly without negatively influencing sensory perception. Therefore, two types of MPs were prepared: heat- and cold-gelated MPs. In addition, pea protein isolate, soy protein isolate, lupin protein concentrate and vital wheat gluten particles were used. To determine their water-binding capacity (WBC), pellets were made by centrifuging dispersions of those particles. These measurements showed that some of these pellets can bind ≥ 90% w/w water. However, the WBC of a pellet contains both water bound within and between the particles, which means that the WBC of a pellet is always unequal to the WBC of the protein particles themselves. To gain more insight in these two water domains and the pellet as a whole, a combination of time domain nuclear magnetic resonance and microscopy was found to be useful. From the measurements, it was concluded that the WBC of a pellet is determined by the structure of protein particles (nanostructure) as well as the structure between particles (microstructure). Overall, the WBC of pellets being larger than that of particles themselves suggests that pellets are a good alternative to the use of MPs for the purpose of increasing the water content of a product, provided they remain a network in the product.

Bioinspired nanopatterned surfaces via colloidal templating; a pathway for tuning wetting and adhesion
Akerboom, Sabine - \ 2016
University. Promotor(en): Frans Leermakers, co-promotor(en): Marleen Kamperman. - Wageningen : Wageningen University - ISBN 9789462578470 - 198
surface chemistry - surfaces - particles - water - nanotechnology - unimolecular films - adhesion - colloidal properties - oppervlaktechemie - oppervlakten - deeltjes - nanotechnologie - unimoleculaire films - adhesie - colloïdale eigenschappen

We can learn from nature that, next to chemistry, surface structures can be used for tuning different functions of surfaces. In this thesis we present a novel fabrication method using colloidal templating on the air/water interface. Two distinct ways to obtain nanopatterned surfaces are described, namely (i) addition of PDMS on top of the colloidal monolayer and (ii) synthesis of polypyrrole around the particles of the monolayer. An increase in adhesion is found for the nanopatterned PDMS surfaces, and the contact angle of water on the nanopatterned polypyrrole surface is increased.

Ecotoxicological effects and DPB-formation in water treated with SDCC-derived chlorine
Kaag, N.H.B.M. ; Sneekes, A.C. - \ 2016
IMARES (Report / IMARES C079/16) - 25 p.
ecotoxicology - chlorine - disinfectants - water - ecotoxicologie - chloor - ontsmettingsmiddelen
Substraatloos telen bemoeilijkt door gebrek aan kennis microbiologie : heeft de praktijk voldoende geduld?
Streminska, Marta ; Vermeulen, Tycho - \ 2016
horticulture - greenhouse horticulture - cropping systems - agricultural research - soilless culture - water - substrates - microbiology - water temperature - chrysanthemum - lettuces - ornamental herbaceous plants - summer flowers - vegetables - cut flowers - plant protection

De laatste jaren groeien de inzichten in het bodemleven, zowel bij de teelt in de grond als op substraat. Maar die kennis blijkt niet één op één bruikbaar bij een switch naar teelt op water. Telers van chrysant, sla, kruiden en zomerbloemen op water kampen met hardnekkige onbegrepen problemen. “Misschien heb je bij waterteelt wel heel andere nuttige micro-organismen nodig dan nu op de markt zijn.”

Succes- en faalfactoren Agrarisch Waterbeheer
Breman, B.C. ; Linderhof, V.G.M. ; Noij, I.G.A.M. ; Vleemingh, M.P.I. ; Ellen, G.J. - \ 2016
Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2718) - 37 p.
waterbeheer - waterschappen - kaderrichtlijn water - water - landbouw - klimaatadaptatie - water management - polder boards - water framework directive - agriculture - climate adaptation
Dit rapport is het resultaat van een verkenning naar succes- en faalfactoren van agrarisch waterbeheer. Bij agrarisch waterbeheer nemen agrarisch ondernemers zelfstandig, of in samenwerking met anderen, bovenwettelijke maatregelen op het eigen bedrijf, gericht op de opgaven ten aanzien van waterkwaliteit, waterkwantiteit en/of biodiversiteit. Gezien de aard van de wateropgaven in Nederland is het belangrijk dat dit agrarisch waterbeheer goed van de grond komt. Belangrijke succesfactoren daarbij zijn onder andere dat: (1) agrarisch waterbeheer breed wordt benaderd en dat er ook voldoende aandacht is voor waterkwantiteit en de relatie met het bedrijfssysteem; (2) dat agrarisch waterbeheer wordt benaderd als een gezamenlijke opgave waarin uiteenlopende partijen samen werken en verantwoordelijkheid delen; (3) er gekozen wordt voor een meersporenbenadering met onderscheid tussen een gebiedsgerichte-, collectieve-, thematische- en sectorale benadering en (4) dat het financieel en juridisch instrumentarium (o.a. POP3) beter wordt afgestemd op de praktijk van agrarisch waterbeheer.
Electrically excited liquid water : lessons from floating water bridge
Wexler, A.D. - \ 2016
University. Promotor(en): Cees Buisman, co-promotor(en): J. Woisetschläger; E.C. Fuchs. - Wageningen : Wageningen University - ISBN 9789462577039 - 223 p.
water - liquids - electric field - thermodynamics - bridges - equilibrium - disequilibrium - electrodynamics - nuclear magnetic resonance - neutron scattering - infrared spectroscopy - spectroscopy - gas chromatography - electrical conductivity - interferometry - spectral analysis - physics - vloeistoffen (liquids) - elektrisch veld - thermodynamica - bruggen - evenwicht - verstoord evenwicht - elektrodynamica - kernmagnetische resonantie - neutronenverstrooiing - infraroodspectroscopie - spectroscopie - gaschromatografie - elektrische geleidbaarheid - interferometrie - spectraalanalyse - fysica

Water is essential to a healthy and secure world. Developing new technologies which can take full advantage of the unique attributes of water is important for meeting the ever increasing global demand while reducing the production footprint. Water exhibits unexpected departures in more than 70 physical and chemical properties compared to other molecular species of similar chemical composition. The principal cause for this behavior is ascribed to the large number of hydrogen bonds which form between neighboring water molecules. Hydrogen bonds are moderately strong in water and exhibit both electrostatic as well as covalent character. When examining the liquid state these interactions play a significantly role in moderating the interchange between dynamics and structure. In disordered materials such as a liquid there are three length scales of importance: 1) at the microscopic molecular level interactions dominate, 2) the macroscopic level where classical forces act upon the statistically isotropic medium, and 3) the mesoscopic level where heterogeneous interactions dominate through evolving transient structures each with unique dynamical behaviors. The mesoscale is important to most environmental and biological processes and is even more poorly understood than the liquid state in general. The aim of this thesis is to explore the extended molecular behavior of liquid water excited by strong electric field gradients.

The floating water bridge belongs to a larger class of phenomena called electrohydrodynamic (EHD) liquid bridges. These self-suspending liquid catenaries can occur in a number of polar liquids provided the conductivity is low. They exhibit elevated temperatures and bidirectional flow patterns, as well as sub-Hz diameter oscillations. The flow behavior and dynamics of these bridges is complex but can be addressed by continuum level EHD theory. The polarizing effect of the electric field gradient accelerates the fluid tangentially along the surface resulting in a Taylor pump which supplies the bridge with liquid. The free hanging section is stable against gravity within a band of operational parameters whereby the electric field strength is sufficient confine fluid elements within the bridge. A standardized protocol for operating stable EHD bridges in multiple configurations is developed and presented. This is the primary tool used throughout the thesis and provides a macroscopic object for the experimental examination of how forces which typically only occur over a few nanometers in nature affect the organization of polar liquids, notably water. In order to examine the role that the electric field gradient plays in the observed molecular changes found in EHD bridges a simple point-plane electrode system was also employed.

There are available a number of tools which provide complimentary information on chemical and physical processes occurring in the liquid state. A brief introduction is given on the interaction between electromagnetic waves and matter with respect to field theory and methods from atomic physics. The basis for interaction over different length scales is established. Electrochemical characterization includes the quantification and identification of the charge carrying species present, the relative proton concentration, and the complex dielectric response. The vibrational and rotational motion of molecules is measured with a combination of infrared emission spectroscopy and imaging and permits the detection of both the thermal bath and non-equilibrium molecular excited states. The local structure of the liquid matter contained in the bridge can be elucidated through the methods discussed here. X-rays provide information on the electron density whereas neutrons reveal nuclear positions. Together with isotope substitution a complete picture of the motionally averaged local structure of the liquid in the bridge can be recovered. QENS is a special case of inelastic scattering which permits the measurement of diffusion, relaxation, and other slow energy or mass transfer modes in materials using a time-of-flight spectrometer. This data compliments the NMR methods used herein specifically to probe the environment of protons in the system; and to provide clues about the strength of both intra- intermolecular coupling in the system. Very small perturbations in the optical properties of a liquid can be detected using interferometry; these ultimately reflect changes in the polarizability of the liquid which can arise from changes in physical properties. Raman scattering is an inelastic method which can probe changes to the polarizability of a liquid that reflect shifts in the local molecular environment and can be used to determine both local and non-local vibrational coupling.

Magnetic resonance imaging was used to track the flow field present in the bridge without the use of tracer particles; revealing that the bridge has a layered structure, with distinct flow regimes lying one on top of the other. Investigation of the electrochemistry in the water bridge found that protons account for 87% of the charge transport in the bridge. Impedance spectroscopy and pH measurement corroborate the finding that a proton gradient forms across the entire system. The results from elastic neutron and X-ray scattering reveal that the static structure is unchanged within the given accuracy of the employed measurements. However, the systematic analysis of the data using a reverse Monte Carlo computer simulation revealed significant dynamical changes that are reliable above the limited instrument precision. The imposed electric field of an EHD bridge distorts the local Coulombic interactions between molecules altering the dielectric relaxation pathway so that it becomes more favorable for the absorbed energy to become trapped locally for a longer period of time. The electric field in the bridge system is not uniform. Strong field gradients are present which stimulate changes in the molecular polarizability, generating gradients of physical properties, and restricting the allowed rotational-vibrational relaxation transitions. These trends are comparable to those from ultrafast relaxation measurements where the vibrational lifetime of the OH stretch of HDO was found to be significantly shorter in the bridge than in the neat liquid. This absorbed energy, however, remained trapped in a local intermediate state longer in the bridge before being released as a thermal perturbation. The nuclear relaxation dynamics in a glycerol bridge showed similar behavior where the transverse and longitudinal magnetization lifetimes diverged from the expectation values given the systems temperature.

From the experimental observations several features of electrically excited water appear. At the gross continuum level the operation of a floating water bridge results in the production of a charge imbalance between anolyte and catholyte. This is in part due to the enhanced proton mobility in the bridge. Protons no longer are confined to the hydrogen bond mediated Grotthuss mechanism but can travel even faster through a delocalized state. This means that charge can be pumped faster than it can be neutralized resulting in the observed electrochemical differences. The energy level of protons in the conduction channel is the difference between the ground and excited state levels observed as a non-thermal emission feature in the mid-infrared. The proton channel will be active over relatively short distances and will experience interruptions due to fluctuations in molecular position driven by local force gradients. These channels are localized and discontinuous providing the physical basis for the onset of mesoscale dynamic heterogeneity in the excited liquid. The picture begins to emerge whereby local trapping states and long-range cooperative coupling modes dynamically exchange energy. The energy exchange is far from equilibrium and supports multiple transfer mechanisms. At the mesoscale the excited state exhibits traits of a chaotic dynamical system and provides a varied energetic landscape whereby rotational-vibrational transition dipoles, nuclear spin states, and thermodynamic potentials, such as the configurational entropy, non-adiabatically – that is there is a pumping of heat in response to the induced fluctuating gradient fields. The transfer of perturbations from local to collective modes and vice versa requires that the chemical, thermal, and electromagnetic potentials present in the molecular milieu be linked to the entropy production.

This early foray into the non-equilibrium dynamics and mesoscale organization of electrically excited liquid water opens an opportunity to develop technologies which better mimic nature. Taking biological systems as the exemplary standard by which to compare it is necessary to develop soft matter based technical systems which take advantage of the link between electric, magnetic, and thermal fields to drive chemical and physical processes with higher efficiency. Water, as well as other polar liquids, can be locally controlled so as to induce spatial variation in the chemical potential whereby one can imagine a reactor where disparate physical or chemical process can occur in close proximity without the need for rigid segregating structures. Furthermore, this level of control is dynamical such that the organization of the partitioning in the liquid can be changed in time so that the total energy requirement of the intended process is optimized. With such an approach it is conceivable that the size, complexity, and energetic costs of performing many industrial and municipal processes can be reduced. Rather than treating liquids as bulk fluids the opportunity presents itself to use the internal structure and dynamics of liquids to build fluid technologies.

Kringlopen - Waterkringloop : Kennisclip Bogo-project e-learning
Baltissen, A.H.M.C. - \ 2016
Groen Kennisnet
cycling - hydrological cycle - water - water reuse - pot culture - horticulture - biobased economy - teaching materials - kringlopen - hydrologische cyclus - hergebruik van water - potcultuur - tuinbouw - lesmaterialen
Deze kennisclip maakt onderdeel uit van de lesmodule Biobased Economy van het CIV T&U.
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