Een nieuwe en handzame lysimeter: eerste stap naar een nationaal netwerk voor de werkelijke verdamping?

Vrijwel overal op aarde verdampt meer dan de helft van het neerslagwater, ook in Nederland. Toch wordt deze grote verliespost in ons land slechts sporadisch gemeten. Door inspanningen van kennisinstituten, bedrijven en overheid is daarom een lysimeter ontwikkeld. Metingen in 2014 en 2015 op twee locaties vertonen opvallende verschillen, maar ook grote overeenkomsten, met eddy-correlatiemetingen. Schattingen van de verdamping via satellietdata zijn hoger dan de metingen. Tijd daarom, om metingen in het veld te combineren met modellen en waarnemingen vanuit de ruimt

Repositioning of the global epicentre of non-optimal cholesterol

High blood cholesterol is typically considered a feature of wealthy western countries(1,2). However, dietary and behavioural determinants of blood cholesterol are changing rapidly throughout the world(3) and countries are using lipid-lowering medications at varying rates. These changes can have distinct effects on the levels of high-density lipoprotein (HDL) cholesterol and non-HDL cholesterol, which have different effects on human health(4,5). However, the trends of HDL and non-HDL cholesterol levels over time have not been previously reported in a global analysis. Here we pooled 1,127 population-based studies that measured blood lipids in 102.6 million individuals aged 18 years and older to estimate trends from 1980 to 2018 in mean total, non-HDL and HDL cholesterol levels for 200 countries. Globally, there was little change in total or non-HDL cholesterol from 1980 to 2018. This was a net effect of increases in low- and middle-income countries, especially in east and southeast Asia, and decreases in high-income western countries, especially those in northwestern Europe, and in central and eastern Europe. As a result, countries with the highest level of non-HDL cholesterol-which is a marker of cardiovascular riskchanged from those in western Europe such as Belgium, Finland, Greenland, Iceland, Norway, Sweden, Switzerland and Malta in 1980 to those in Asia and the Pacific, such as Tokelau, Malaysia, The Philippines and Thailand. In 2017, high non-HDL cholesterol was responsible for an estimated 3.9 million (95% credible interval 3.7 million-4.2 million) worldwide deaths, half of which occurred in east, southeast and south Asia. The global repositioning of lipid-related risk, with non-optimal cholesterol shifting from a distinct feature of high-income countries in northwestern Europe, north America and Australasia to one that affects countries in east and southeast Asia and Oceania should motivate the use of population-based policies and personal interventions to improve nutrition and enhance access to treatment throughout the world.Peer reviewe

Technical note:A device to directly measure transpiration from vegetation grown in containers

Information about evaporation and transpiration fluxes is vital for water budgets, modeling of water flows and climate, as well as for assessing the hydrological impact of land management practices. Under natural conditions, these fluxes are difficult to measure accurately, which results in large measurement inaccuracies. These inaccuracies can be reduced in controlled experiments. We present a device that is especially useful for transpiration studies conducted in large and/or heavy containers where weighing becomes too cumbersome or expensive. With our device we set a water table and control soil moisture of potted small trees by periodically replenishing soil water consumed by the tree, thereby measuring the inflow volume, which represent whole-tree transpiration. The device is made of inexpensive, easily available and durable materials and can be used for in- and outdoor experiments. Data acquisition is fast and easy. The mean measurement error of the device is 4.5% (±3.2% SD) for refill (i.e., transpiration) volumes of 1.5 L or larger. For a transpiring surface of 3 m2, this amount is equal to an accuracy of 0.02 mm. Validation on field data showed that transpiration measured by the device is comparable to transpiration measured by gravimetric changes

Verdamping van droogteminnende duinvegetatie : Extended abstract

Op 21 september 2018 was de openbare verdediging van het proefschrift "Evaporationfrom dry dune vegetation" door Bernard Voortman. Het proefschrift biedt kwantitatieve inzichten in het verdampingsgedrag van droogteminnende duinvegetaties in vroegesuccessiestadia (kaal zand, mos, gras en heide). We onderzochten onder andere de invloed van het dichtgroeien van natuurgebieden en van het veranderende klimaat op deverdamping. Deze inzichten komen ten goede aan betere grondwatermodellen, maarook aan de vergroting van de grondwateraanvulling via een gericht vegetatiebeheer

The effect of plant size and branch traits on rainfall interception of 10 temperate tree species

Rainfall interception by vegetation plays an important role in the hydrological cycle. Next to rainfall characteristics, interception is influenced by tree size, crown structure and bark morphology. How tree traits determine interception across functionally and morphologically wide-ranging tree species is poorly understood. We determined interception ratios (interception:gross precipitation) and canopy storage capacities of seven temperate deciduous broadleaved (Acer pseudoplatanus L., Betula pendula Roth, Carpinus betulus L., Fagus sylvatica L., Populus tremula L., Sorbus aucuparia L.) and three evergreen coniferous tree species (Picea abies (L.) Karsten, Pinus sylvestris L., Pseudotsuga menziesii (Mirb.) Franco) as well as the influence of various tree traits on interception parameters. Interception was measured directly with natural rainfall by means of gravimetry on potted trees, 2–8 m tall, for seven consecutive months. Our results show that (a) the coniferous species had larger canopy storage capacities and larger interception ratios than the broadleaved species both during (summer) and outside the growing season (winter); (b) the absolute tree interception (in kg) of the broadleaved species was positively related to stem diameter at breast height, tree and crown height, maximum branch length, the total branch surface area and above ground dry weight; and (c) interception per unit crown projected area (in mm) of all species was positively related to branch length and branch surface area per unit crown projected area. These results can be used to estimate interception parameters from plant traits and to simulate interception losses of trees in a more reliable manner

Evaporation from (Blue-)Green Roofs : Assessing the benefits of a storage and capillary irrigation system based on measurements and modeling

Worldwide cities are facing increasing temperatures due to climate change and increasing urban density. Green roofs are promoted as a climate adaptation measure to lower air temperatures and improve comfort in urban areas, especially during intensive dry and warm spells. However, there is much debate on the effectiveness of this measure, because of a lack of fundamental knowledge about evaporation from different green roof systems. In this study, we investigate the water and energy balance of different roof types on a rooftop in Amsterdam, the Netherlands. Based on lysimeter measurements and modeling, we compared the water and energy balance of a conventional green roof with blue-green roofs equipped with a novel storage and capillary irrigation system. The roofs were covered either with Sedum or by grasses and herbs. Our measurements and modeling showed that conventional green roof systems (i.e., a Sedum cover and a few centimeters of substrate) have a low evaporation rate and due to a rapid decline in available moisture, a minor cooling effect. Roofs equipped with a storage and capillary irrigation system showed a remarkably large evaporation rate for Sedum species behaving as C3 plants during hot, dry periods. Covered with grasses and herbs, the evaporation rate was even larger. Precipitation storage and capillary irrigation strongly reduced the number of days with dry-out events. Implementing these systems therefore could lead to better cooling efficiencies in cities.</p

Verdamping van droogteminnende duinvegetatie : Extended abstract

Op 21 september 2018 was de openbare verdediging van het proefschrift "Evaporationfrom dry dune vegetation" door Bernard Voortman. Het proefschrift biedt kwantitatieve inzichten in het verdampingsgedrag van droogteminnende duinvegetaties in vroegesuccessiestadia (kaal zand, mos, gras en heide). We onderzochten onder andere de invloed van het dichtgroeien van natuurgebieden en van het veranderende klimaat op deverdamping. Deze inzichten komen ten goede aan betere grondwatermodellen, maarook aan de vergroting van de grondwateraanvulling via een gericht vegetatiebeheer

Capnocytophaga species and perinatal infections: case report and review of the literature.

Capnocytophaga species are part of the normal human oral bacterial flora.They are recognized as opportunistic pathogens leading to various extra-oral infections including septicemia, osteomyelitis, abscesses and keratitis and they have been rarely reported as a cause of chorioamionitis and neonatal infection. We here report the first two cases of chorioamionitis produced by Capnocytophaga sputigena and the recently described C. leadbetteri in Belgium. Both isolates were correctly identified at the genus level, in the first 24 hours of incubation by MALDI-TOF