Een eerste inschatting van het Urban Heat Island effect voor Rotterdam en omgeving – een modelstudie

Tot nu toe is weinig bekend over het warmte-eiland effect in Nederland. Het doel van deze studie is om door middel van een modelstudie een eerste inschatting te maken van het warmte-eiland effect van de stad Rotterdam en naastgelegen omgeving, voor twee episodes in een hittegolf (in 2003, en 2006). Hiervoor wordt gebruik gemaakt van het mesoschaal meteorologisch model WRF, dat is uitgerust met een aparte module voor het stedelijk klimaa

The mechanism of NH3 and SO2 uptake by leaves and its physiological effects = [Het mechanisme van de NH3 en SO2 opname door bladeren en hierdoor veroorzaakte fysiologische effecten]

The relation between uptake of atmospheric ammonia (NH 3 ) and sulphur dioxide (SO 2 ) by individual leaves, photosynthesis and stomatal conductance was examined. The experiments were carried out with bean plants ( Phaseolus vulgaris L. ) and poplar shoots ( Populus euramericana L. ). The method of analysis was derived from methods used in photosynthetic research. The uptake of NH 3 or SO 2 was experimentally determined by using a leaf chamber specially developed for this research. Simultaneously, transpiration and carbondioxide (CO 2 ) assimilation of leaves were measured.The adsorption of NH 3 and SO 2 strongly increased with increasing air humidity, indicating a major role of water in the adsorption process. A descriptive model for the adsorption in the cuticle-watersystem is proposed. The affinity of SO 2 for the leaf surface was found to be approximately twice that of NH 3 . A mixture of these gases in the air mutually stimulated their adsorption on the leaf surface. No significant desorption or transport of these gases through the cuticle could be detected.The uptake of NH 3 into leaves appeared to be dependent on the leaf boundary layer and stomatal resistance and NH 3 concentration at the leaf surface. In contrast, a less clear relation between SO 2 uptake and stomatal resistance was found, in particular at a low vapor pressure deficit (VPD). The measured flux was larger than can be calculated from the boundary layer and stomatal resistance for H 2 O, suggesting a lower resistance of the diffusion pathway. The same was observed for NH 3 at a low temperature and VPD. It is postulated that this discrepancy is due to a difference in path length.Under the conditions of the present research the physiological effects caused by a prolonged exposure to NH 3 or SO 2 became notable at concentrations of about 100 μg.m -3. The NH 3 exposure had a positive effect on photosynthesis, stomatal conductance and NH 3 uptake, whereas a small irreversible inhibition of photosynthesis and stomatal conductance was induced by the SO 2 exposure.The relations assessed in this study can be used to construct a descriptive model for NH 3 and SO 2 transfer into leaves as a function of wind velocity, light intensity, air temperature and humidity

Use of a mobile platform for assessing urban heat stress in Rotterdam

In this study, an assessment of the intensity of the urban heat island (UHI) in Rotterdam was carried out using an innovative mobile bio-meteorological measuring platform mounted on a cargo bicycle. The goal was to assess whether or not heat stress is currently or likely to become a critical issue. Physiological equivalent temperatures were calculated directly from the measurements. Preliminary results show how effective urban parks and greenery are in reducing the UHI. The maximum UHI was about 7 K warmer than the rural area, whereas greener urban configurations were under 3 K warmer. City parks show marked cooling effects during daytime. The preliminary results clearly demonstrate the presence of a considerable UHI in Rotterdam, which is expected to be found in other Dutch cities, and confirms the important role of green spaces in mitigating urban heat stress

De invloed van de geplande groengebieden nabij de N201 op de achtergrondconcentratie van fijn stof

Onderzoek in hoeverre de geplande groengebieden in het plangebied van de N201 kunnen bijdragen aan een verlaging van de achtergrondconcentratie nabij het nieuwe tracé van de N20