Search

In this paper, we reconstruct the vertical profile of volcanic ash emissions by assimilating satellite data and ground‐based observations using a modified trajectory‐based 4D‐Var (Trj4DVar) approach. In our previous work, we found that the lack of vertical resolution in satellite ash column data can result in a poor estimation of the injection layer where the ash is emitted into the atmosphere. The injection layer is crucial for the forecast of volcanic ash clouds. To improve estimation, Trj4DVar was implemented, and it has shown increased performance in twin experiments using synthetic observations. However, there are some cases with real satellite data where Trj4DVar has difficulty in obtaining an accurate estimation of the injection layer. To remedy this, we propose a modification of Trj4DVar, test it with synthetic twin experiments, and evaluate real data performance. The results show that the modified Trj4DVar is able to accurately estimate the injection height (location of the maximal emission rate) by incorporating the plume height (top of the ash plume) and mass eruption rate data obtained from ground‐based observations near the source into the assimilation system. This will produce more accurate emission estimations and more reliable forecasts of volcanic ash clouds. Also provided are two strategies on the preprocessing and proper use of satellite data.

Mapping of road traffic noise in urban areas according to standardized engineering calculation methods systematically results in an underestimation of noise levels at areas shielded from direct exposure to noise, such as inner yards. In most engineering methods, road traffic lanes are represented by point sources and noise levels are computed utilizing point-to-point propagation paths. For a better prediction of noise levels in shielded urban areas, an extension of engineering methods by an attenuation term Acan has been proposed, including multiple reflections of the urban environment both in the source and in the receiver area. The present work has two main contributions for the ease of computing Acan. Firstly, it is shown by numerical calculations that Acan may be divided into independent source and receiver environment terms, As and Ar. Based on an equivalent free field analogy, the distance dependence of these terms may moreover be expressed analytically. Secondly, an analytical expression is proposed to compute As and Ar for 3D configurations from using 2D configurations only. The expression includes dependence of the street width-to-height ratio, the difference in building heights and the percentage of facade openings in the horizontal plane. For the expression to be valid, the source should be separated from the receiver environment by at least four times the street width. © S. Hirzel Verlag EAA.

The capacity of Particulate Matter (PM) to oxidise target molecules, defined as its oxidative potential (OP), has been proposed as a biologically more relevant metric than PM mass. Different assays exist for measuring OP and their methodologies vary in the choice of extraction solvent and filter type. Little is known about the impact of extraction and filter type on reported OP. Four a-cellular assays; electron spin resonance (ESR), dithiothreitol (DTT), ascorbate acid depletion (AA) and reductive acridinium triggering (CRAT) assay were chosen to evaluate whether these differences affect the OP measurement, the correlation between OP from different assays and the association with PM chemical composition. We analysed 15 urban 48-72h PM2.5 samples collected on quartz and Teflon filters. The choice of extraction solvent had only a significant effect on OPDTT, while all OP measures for quartz filters were heavily attenuated. OP values derived from quartz were, however, highly correlated with those derived from Teflon. OPDTT correlated highly with OPCRAT, and OPESR correlated highly with OPAA. These correlations were affected by the choice of filter type. Correlations between OP and PM chemical composition were not affected by filter type and extraction solvent. These findings indicate that the measurement of relative OP reactivity is not greatly influenced by filter type and extraction solvent for the investigated assays. This robustness is also promising for exploratory use in monitoring and subsequent epidemiological studies. © 2013 The Authors.

This study examines the global variation in particle size distribution simulated by twelve global aerosol microphysics models to quantify model diversity and to identify any common biases against observations. Evaluation against size distribution measurements from a new European network of aerosol supersites shows that the mean model agrees quite well with the observations at many sites on the annual mean, but there are some seasonal biases common to many sites. TNO contributed to this study with aerosol observations from supersite Cabauw.

Pollution levels in urban areas and their surrounding rural regions differ due to different sources and density of emissions, different composition of pollutants as well as specific meteorological effects. These concentration differences for PM10 are investigated and compared in this study for three different north-west European urban agglomerations: The German Ruhr area, the Dutch Randstad and the German city of Berlin. Measurement data for PM10 for the years 2003-2008 at urban and rural background stations are selected from the AirBase database to specify the PM10 concentration difference between these urban areas and their surrounding rural regions, here defined as the urban increment. Whereas the absolute and relative measured urban increment averaged over the years 2003-2008 for the Ruhr area (7.4μgm-3, 35%) and Berlin (8.5μgm-3, 46%) are comparable in magnitude, a significantly smaller value is found for the Randstad (3.1μgm-3, 12%). To analyze whether the regional chemistry transport model LOTOS-EUROS is able to reproduce the measured urban increment simulation runs were performed for 2003-2008 on a 0.5°×0.25° lon-lat grid covering Europe and for the year 2008 on a finer grid of 0.125°×0.0625° covering the Netherlands and Germany, both with ECMWF meteorology as input. Although the model underestimates the absolute PM10 urban increment averaged over the years 2003-2008 for the Ruhr area (3.3μgm-3, 33%), the Randstad (1.5μgm-3, 12%) and Berlin (1.7μgm-3, 27%), the relative urban increment for the Ruhr area and the Randstad is in general agreement with the measurements. The tested increase of the horizontal resolution gives no systematic improvement of the simulated urban increment. However, an even higher resolution than used here seems to be more appropriate to capture the urban increment (especially for Berlin).The variability of the PM10 urban increment with weather is tested by means of the summer 2003, such an extreme synoptic situation is expected to occur more often in future. Measured and simulated PM10 concentrations in summer 2003 were compared to the summer average of 2003-2008. The response of the observed urban increment was found to depend on the urban area. In general the model reproduces the main features for the Randstad and Berlin.In order to investigate the impact of a changing climate on the PM10 urban increment, simulations were performed with the off-line coupled model system RACMO2 (regional climate model) - LOTOS-EUROS (air quality model) over Europe. Different sets of simulations were carried out using RACMO2 meteorology with ECHAM5 A1B and with MIROC3.2-hires A1B boundary conditions for the time period 1970-2060, as well as with ERA-interim boundary conditions for the time period 1989-2009. Anthropogenic emissions were kept constant in the LOTOS-EUROS simulations. Simulated concentrations differ between the runs using ECHAM and MIROC boundary conditions and both runs differ from the present-day simulations with ERA-interim forcing. The impact of climate change on the modeled PM10 concentrations and the urban increment was found to be small in both scenario runs. However the concentration differences between the simulations forced by either ECHAM or MIROC indicate that PM10 concentration levels are sensitive to circulation patterns rather than temperature change alone, and that PM10 concentration levels may thus change when circulation patterns change in the future. © 2013 Elsevier Ltd.

In the Netherlands the groundwater-surface water interaction processes vary spatially and temporarily. In this article we present maps of the spatial distribution of monthly water exchange modelled with the National Hydrological Instrument of the Netherlands (NHI) for three years that represent a dry, an average and a wet year. Additionally, for five characteristic regions we present the exchange in more detail, both the temporal variability and the origin of water fluxes. The simulation results provide a better understanding of the hydrogeological system. The Dutch water authorities use the maps in the planning process of measures to fulfil the framework directive of the European Union.

The presence of clay in fault zones has a dramatic effect on both fault mechanics and permeability. Quantification of this effect relies on small scale laboratory experiments or indirect observations from hydrocarbon fields, for which systematic variation of clay content, clay distribution, and deformation conditions can be problematic. Two-dimensional discrete element models of fault zones were deformed in simple shear to assess the effect of shale on failure criteria and sealing capacity using a systematic series of model simulations. Comparison between the evolution of shear stress and development of microcracks shows that changes in shear stress are correlated with alignment of microcracks, resulting in fractures with similar orientations as R- and Y-shears that can accommodate local deformation. Both shale content and distribution have a marked effect on the failure criteria of all fault models, i.e. with increasing volumetric shale content cohesion decreases up to a factor ~20 and friction coefficients drops below ~0.1 for some distributions. A tradeoff between permeability reduction due to the presence of low permeable clay and permeability increase due to local failure of fault rock determines the location of spill points and integrity of fault seals during gas storage

An overview of regional-scale quality modeling practices and perspectives in North America and Europe, highlighting the differences and commonalities in how regional-scale air quality modeling systems are being used and evaluated across both continents

Buiten vastgestelde kaders denken draagt wezenlijk bij aan het verbeteren van onze veiligheid. In Nederland is dit echter uitermate moeilijk. Eerste stap om de huidige praktijk te verbeteren vormt het standaard inschakelen van het RIVM

In the present paper heavy gas dispersion calculations were performed with OpenFoam. For a windtunnel test case, numerical data was validated with experiments. For a full scale numerical experiment,a code to code comparison was performed with numerical results obtained from Fluent. The validationwas performed in a gravity driven environment (slope), where the heavy gas induced the turbulence.For the code to code comparison, a hypothetical heavy gas release into a strongly turbulent atmosphericboundary layer including terrain effects was selected. The investigations were performed for SF6and CO2as heavy gases applying the standard k–ε turbulence model. A strong interaction of the heavy gas with theturbulence is present which results in a strong damping of the turbulence and therefore reduced heavygas mixing. Especially this interaction, based on the buoyancy effects, was studied in order to ensure thatthe turbulence-buoyancy coupling is the main driver for the reduced mixing and not the global behaviourof the turbulence modelling.For both test cases, comparisons were performed between OpenFoam and Fluent solutions which weremainly in good agreement with each other. Beside steady state solutions, the time accuracy was inves-tigated. In the low turbulence environment (wind tunnel test) which for both codes (laminar solutions)was in good agreement, also with the experimental data. The turbulent solutions of OpenFoam werein much better agreement with the experimental results than the Fluent solutions. Within the strongturbulence environment, both codes showed an excellent comparability.

Mapping the Middle to Upper Pleistocene Rhine-Meuse sequence in the southern North Sea based on new core and seismic data has allowed a detailed palaeoenvironmental re-assessment. An integrated seismo-lithostratigraphic and malacological biostratigraphic framework is correlated with the optically stimulated luminescence-dated Rhine-Meuse sequence onshore. The data point to a dynamic interplay of fluvial and marine systems in the southern part of the North Sea driven by longer-term (>100 ka) tectonic and epeirogenic processes and shorter-term (100 ka) uplift of the Wealden-Artois synclinorium and compaction-driven subsidence of Tertiary shales within the Voorne Trough. The dominant erosive sedimentary signatures within the Rhine-Meuse sequence resulted through shorter-term (

Several types of diesel exhaust particles (DEPs) have been used for toxicology studies, including a highorganic automobile DEP (A-DEP) from Japan, and a low-organic forklift DEP developed by the National Institute of Standards and Technology (N-DEP). However, these DEPs were not characterized extensively for chemical composition or sub-fractionated and tested extensively for mutagenicity. We collected a compressor-generated DEP (C-DEP) and characterized it by conducting bioassay-directed fractionation of the extractable organics in Salmonella and correlating the results by hierarchical clustering with the concentrations of 32 polycyclic aromatic hydrocarbons (PAHs). Relative to A- and N-DEP, the mutagenic potency of C-DEP was intermediate in TA100 1S9 (PAH mutagenicity) but was lowest in TA98 – S9 (nitroarene mutagenicity). More than 50% of the mass of the extractable organics of C-DEP eluted in the nonpolar fraction 1, and only -20% eluted in the moderately polar Fractions 2 and 3. However, most of the mutagenicity eluted in Fractions 2 and 3, similar to A-DEP but different from N-DEP. HPLC-derived mutagrams of 62 sub-fractions per fraction confirmed that most of the mutagenicity was due to moderately polar compounds. The diagnostic strains identified a strong role for PAHs, nitroarenes, aromatic amines, and oxy-PAHs in the mutagenicity of C-DEP. Hierarchical clustering confirmed the importance of oxy-PAHs but not that of nitroarenes. To our knowledge this is the first use of hierarchical clustering to correlate chemical composition with the mutagenicity of a complex mixture. The chemical analysis and mutagenicity of C-DEP described here makes C-DEP suitable for additional toxicological studies.

The atmospheric organic aerosol composition is characterized by a great diversity of functional groups and chemical species challenging simple classification schemes. Traditional off-line chemical methods identified chemical classes based on the retention behavior on chromatographic columns and absorbing beds. Such approach led to the isolation of complex mixtures of compounds such as the humic-like substances (HULIS). More recently, on-line aerosol mass spectrometry (AMS) was employed to identify chemical classes by extracting fragmentation patterns from experimental data series using statistical methods (factor analysis), providing simplified schemes for oxygenated organic aerosols (OOAs) classification on the basis of the distribution of oxygen-containing functionalities. The analysis of numerous AMS datasets suggested the occurrence of very oxidized OOAs which were postulated to correspond to the HULIS. However, only a few efforts were made to test the correspondence of the AMS classes of OOAs with the traditional classification from the off-line methods. In this paper, we consider a case study representative for polluted continental regional background environments. We examine the AMS factors for OOAs identified by positive matrix factorization (PMF) and compare to chemical classes of water-soluble organic carbon (WSOC) analysed off-line on a set of filters collected in parallel. WSOC fractionation was performed by means of factor analysis applied to H-NMR spectroscopic data, and by applying an ion-exchange chromatographic method for direct quantification of HULIS. Results show that the very oxidized low-volatility OOAs from AMS correlate with the NMR factor showing HULIS features and also with true “chromatographic” HULIS. On the other hand, UV/VIS-absorbing polyacids (or HULIS sensu stricto) isolated on ion-exchange beds were only a fraction of the AMS and NMR organic carbon fractions showing functional groups attributable to highly substituted carboxylic acids, suggesting that unspeciated low-molecular weight organic acids contribute to HULIS in the broad sense.

The advent of satellite data has provided a source of independent information to monitor trends in tropospheric nitrogen dioxide levels. To interpret these trends, one needs to know the sensitivity of the satellite retrieved NO2 column to anthropogenic emissions. We have applied a chemistry transport model to investigate the sensitivity of the modeled NO2 column, sampled at the OMI (Ozone Monitoring Instrument) overpass time and location and weighted by the OMI averaging kernel, to emission sources across Europe. The most important contribution (~35%) in Western Europe is made by road transport. Off-road transport and industrial combustion each contribute 10%-15% across continental Europe. In Eastern Europe, power plant contributions are of comparable magnitude as those of road transport. To answer the question if the OMI-NO2 trends can be translated directly into emission changes, we assessed the anticipated changes in OMI-NO2 between 2005 and 2020. Although the results indicated that for many countries, it is indeed possible, for medium- and small-sized coastal countries, the contribution of the increasing shipping emissions in adjacent sea areas may mask a significant part of national emission reductions. This study highlights the need for a combined use of models, a priori emission estimates and satellite data to verify emission trends. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Het Nederlandse externe veiligheidsbeleid in relatie tot gevaarlijke stoffen is gebaseerd op de resultaten van de kwantitatieve risico analyse (QRA). Echter het standaard instrumentarium leent zich niet voor alle risico's van stationaire installaties zoals bleek btj het uitvoeren van de QRA voor Solvay Chemie in Herten nabij Roermond. De inrichting is aangewezen als BRZO-bedrijf vanwege het overschrrjden van de drempelwaarde voor oxiderende stoffen, genoemd in 'Besluit Risico Zware Ongevallen 1999' (4). Het gaat om de stof perazijnzuur. QRA berekeningen in Nederland moeten op geünificeerde wijze worden uitgevoerd volgens de Rekenmethodiek Bevi die bestaat uit de Handleiding Risicoberekeningen Bevi [3] en het rekenpakket Safeti-Nl. Bij een risicoanalyse worden zowel de effecten als de kansen van ongewenste voorvallen in beeld gebracht. In dit artikel wordt met name de effectenkant van de risicoanalyse belicht omdat juist de te berekenen effecten buiten de standaardkaders van de Handleiding Risicoberekening BEVI en Safeti-Nl, vallen. Zo voorzíet de geünificeerde werkwijze voor QRA berekeningen niet in het hanteren van mengsels (perazijnzuur en oleum), noch in het berekenen van niet-standaard scenario's zoals runaway reacties en ontleding van de gevaarlijke stof (perazijnzuur).

Leaching of nitrate from agricultural land to groundwater and the resulting nitrate pollution are a major environmental problem worldwide. Its impact is often mitigated in aquifers hosting sufficiently reactive reductants that can promote autotrophic denitrification. In the case of pyrite acting as reductant, however, denitrification is associated with the release of sulfate and often also with the mobilization of trace metals (e.g., arsenic). In this study, reactive transport modeling was used to reconstruct, quantify and analyze the dynamics of the dominant biogeochemical processes in a nitrate-polluted pyrite-containing aquifer and its evolution over the last 50 years in response to changing agricultural practices. Model simulations were constrained by measured concentration depth profiles. Measured 3H/3He profiles were used to support the calibration of flow and conservative transport processes, while the comparison of simulated and measured sulfur isotope signatures acted as additional calibration constraint for the reactive processes affecting sulfur cycling. The model illustrates that denitrification largely prevented an elevated discharge of nitrate to surface waters, while sulfate discharges were significantly increased, peaking around 15 years after the maximum nitrogen inputs. © 2013 American Chemical Society.

A 3D geological raster model has been constructed of the onshore of the Netherlands. The model displays geological units for the upper 500 m in 3D in an internally consistent way. The units are based on the lithostratigraphical classification of the Netherlands. This classification is used to interpret a selection of boreholes from the national subsurface database. Additional geological information regarding faults, the areal extent of each unit and conceptual genetic models have been combined in an automated workflow to interpolate the basal surfaces of each unit on 100 × 100 metre (x,y dimensions) raster cells. The combination of all interpolated basal surfaces results in a 3D Digital Geological Model (DGM) of the subsurface. A measure of uncertainty of each of these surfaces is also given. The automated workflow ensures an easily updatable subsurface model. The outputs are available for end users through www.dinoloket.nl.

The ECCO Tool [1, 2] has been developed in the “ECCO – European value chain for CO2” project [3]. ECCO was a collaborating project under the 7th framework programme for research of the EU. The ECCO Tool is a software program designed to evaluate quantitatively the post-tax economics of Carbon Capture and Storage (CCS) projects for each of the mutually dependent actors along the CCS value chain. The main objective of ECCO is to facilitate robust strategic decision-making regarding early and future deployment of CO2 value chains [4]. The tool is designed to have a level of detail that is appropriate for studying the economic feasibility of welldefined CCS projects to be executed by commercial companies, studying whether or not to invest in (part of) the value chain and, if so, under which contractual conditions. The tool integrates cost engineering, transport and well/reservoir physics, planning (including the impact of contracts and physics on the sizing and timing of capex and opex), and full post-tax economics (including macro- and micro-economics). The ECCO Tool is also aimed at giving insight to national and European policy makers on their possible role in “closing the chain”,i.e., how they may contribute, through subsidies, guarantees, regulation or otherwise, to achieve a satisfactory risk and/or reward for the actors involved in a chain. Finally, the tool can also be used by authorities to estimate the potential of CCS in realizing overall policy objectives (e.g. meeting ETS objectives, amount of government stimulation needed, jobs created, etc). The subsurface module consists of three storage options, depleted gas field (DGF), aquifer and storage by enhanced oil recovery (EOR). In order to have a realistic behavior of the subsurface operator, automatic decision algorithms are included in the subsurface module. In order to meet the contractual obligations of the storage operator, e.g. to store a volume of CO2 within a certain period, incremental investments may be needed. These incremental investments depend on physical and contractual state-variables that are calculated as output of the subsurface module. Decision algorithms for incremental investments can be formulated such that the actual decisions are triggered as a function of these state variables

Compound-specific stable isotope analysis (CSIA) has, in combination with model-assisted interpretation, proven to be a valuable approach to quantify the extent of organic contaminant degradation in groundwater systems. CSIA data may also provide insights into the origin and transformation of diffuse pollutants, such as pesticides and nitrate, at the catchment scale. While CSIA methods for pesticides have increasingly become available, they have not yet been deployed to interpret isotope data of pesticides in surface water. We applied a coupled subsurface-surface reactive transport model (HydroGeoSphere) at the hillslope scale to investigate the usefulness of CSIA in the assessment of pesticide degradation. We simulated the transport and transformation of a pesticide in a hypothetical but realistic two-dimensional hillslope transect. The steady-state model results illustrate a strong increase of isotope ratios at the hillslope outlet, which resulted from degradation and long travel times through the hillslope during average hydrological conditions. In contrast, following an extreme rainfall event that induced overland flow, the simulated isotope ratios dropped to the values of soil water in the pesticide application area. These results suggest that CSIA can help to identify rainfall-runoff events that entail significant pesticide transport to the stream via surface runoff. Simulations with daily rainfall and evapotranspiration data and one pesticide application per year resulted in small seasonal variations of concentrations and isotope ratios at the hillslope outlet, which fell within the uncertainty range of current CSIA methods. This implies a good reliability of in-stream isotope data in the absence of transport via surface runoff or other fast transport routes, since the time of measurement appears to be of minor importance for the assessment of pesticide degradation. The analysis of simulated isotope ratios also allowed quantification of the contribution of two different reaction pathways (aerobic and anaerobic) to overall degradation, which gave further insight into the transport routes in the modelled system. The simulations supported the use of the commonly applied Rayleigh equation for the interpretation of CSIA data, since this led to an underestimation of the real extent of degradation of less than 12% at the hillslope outlet. Overall, this study emphasizes the applicability and usefulness of CSIA in the assessment of diffuse river pollution, and represents a first step towards a theoretical framework for the interpretation of CSIA data in agricultural catchments.©Author(s) 2013.

A multi-analytical approach to chemical analysis of inhalable urban atmospheric particulate matter (PM), integrating particle induced X-ray emission, inductively coupled plasma mass spectrometry/atomic emission spectroscopy, chromatography and thermal-optical transmission methods, allows comparison between hourly (Streaker) and 24-h (High volume sampler) data and consequently improved PM chemical characterization and source identification. In a traffic hot spot monitoring site in Madrid (Spain) the hourly data reveal metallic emissions (Zn, Cu, Cr, Fe) and resuspended mineral dust (Ca, Al, Si) to be closely associated with traffic flow. These pollutants build up during the day, emphasizing evening rush hour peaks, but decrease (especially their coarser fraction PM2.5-10) after nocturnal road washing. Positive matrix factorization (PMF) analysis of a large Streaker database additionally reveals two other mineral dust components (siliceous and sodic), marine aerosol, and minor, transient events which we attribute to biomass burning (K-rich) and industrial (incinerator?) Zn, Pb plumes. Chemical data on 24-h filters allows the measurement of secondary inorganic compounds and carbon concentrations and offers PMF analysis based on a limited number of samples but using fuller range of trace elements which, in the case of Madrid, identifies the continuing minor presence of a coal combustion source traced by As, Se, Ge and Organic Carbon. This coal component is more evident in the city air after the change to the winter heating season in November. Trace element data also allow use of discrimination diagrams such as V/Rb vs. La/Ce and ternary plots to illustrate variations in atmospheric chemistry (such as the effect of Ce-emissions from catalytic converters), with Madrid being an example of a city with little industrial pollution, recently reduced coal emissions, but serious atmospheric contamination by traffic emissions. © 2012 Elsevier Ltd.

The study presented in this paper is to investigate the possibility of using spaceborne remote sensing data for groundwater head prediction. Remotely-sensed soil moisture time series of SWI (Soil Water Index) derived from ERS (European Remote Sensing) scatterometers are used to predict groundwater head dynamics in the Rhine-Meuse basin, where over four thousand observed groundwater head time series are available. Our study consists of three evolving research steps. First, the correlation between observed time series of groundwater head and SWI is investigated. Second, SWI time series are used as input to a transfer-function noise (TFN) model for temporal prediction (forecasts) of groundwater heads. Third, TFN models with spatially interpolated parameters are used with SWI time series for spatio-temporal prediction of groundwater heads. Here, HAND (Height Above Nearest Drainage) as derived from a digital elevation model is used as auxiliary information. Results show that the correlation between SWI and groundwater head time series is apparent, particularly in areas with shallow groundwater, and that correlation increases when a time-lag is taken into account. Temporal predictions with TFN models reproduce observed groundwater head time series well at locations with shallow groundwater, but results are poor for locations with deep groundwater. The spatio-temporal prediction method is not able to estimate the absolute value of groundwater heads. However, head variation in terms of timing and amplitude is predicted reasonably well, in particular in areas with shallow groundwater. This suggests that, once a groundwater model is suitably calibrated, remotely sensed soil moisture data could be used to improve groundwater prediction in an operational data-assimilation framework. © 2013 Elsevier Inc.

In the current work evaluation of CO2 release velocity profiles is determined using Particle Image Velocimetry (PIV). The formation of solid CO2 particles using the rapid expansion of nozzle flow is used as a seeder particle, making the method truly nonintrusive and negates the use of special seeder equipment. Preliminary tests have been conducted on low speed large CO2 particles. High-speed release PIV experiments have been conducted for a range of storage pressures between 60 and 150 bars using a 13 mm (1/2 inch) diameter nozzle. The current paper is reporting combined research with a second paper by Dam et al. . The current investigation is a small scale experiment prior to reported mid scale experiments reported in Ahmed et al.

The circum-Antarctic Southern Ocean is an important region for global marine food webs and carbon cycling because of sea-ice formation and its unique plankton ecosystem. However, the mechanisms underlying the installation of this distinct ecosystem and the geological timing of its development remain unknown. Here, we show, on the basis of fossil marine dinoflagellate cyst records, that a major restructuring of the Southern Ocean plankton ecosystem occurred abruptly and concomitant with the first major Antarctic glaciation in the earliest Oligocene (∼33.6 million years ago). This turnover marks a regime shift in zooplankton-phytoplankton interactions and community structure, which indicates the appearance of eutrophic and seasonally productive environments on the Antarctic margin. We conclude that earliest Oligocene cooling, ice-sheet expansion, and subsequent sea-ice formation were important drivers of biotic evolution in the Southern Ocean.

The impact of large cities on air pollution levels usually is determined with models driven by so-called downscaled emission inventories. This implies that annual emissions of air pollutants at the national scale are spatially distributed over a grid using proxy data like population density. These inventories are frequently used for regional air quality modeling but increasingly used also to assess air quality over cities. A key question is how much the assessment of city air pollution and exposure is influenced by downscaling of emission input data.Within this study we compare modeled nitrogen dioxide and particulate matter (PM) concentrations driven by a downscaled emission inventory with modeled concentrations driven by a 'bottom-up' emission inventory for the Paris region. Predicted concentrations and gradients in the concentrations are more consistent with observed concentrations when using the local bottom-up inventory. Both emissions and simulated concentrations of PM over urban sites in Paris are much lower due to different spatial distribution of the anthropogenic emissions. The difference for nearby rural stations is small implicating that the PM urban increment is much smaller than when using the downscaled emission inventory. Urban increments for PM based on conventional downscaled emissions may therefore be overestimated. © 2013 Elsevier Ltd.

Het werkterrein van TNO is aanzienlijk breder dan de tuinbouw alleen. Maar onderzoek in 'vreemde sectoren' levert geregeld inzichten op die ook bruikbaar zijn in de teelt van groenten, bloemen en planten. ln elke editie van GTT Magazine nemen wij een project van TNO onder de loep. Dit keer wél aandacht voor een 'echt tuinbouwproject', genaamd NoWaste.

Aerosol observations over the Arctic are important because of the effects of aerosols on Arctic climate, such as their direct and indirect effects on the Earth's radiation balance and on snow albedo. Although information on aerosol properties is available from ground-based measurements, passive remote sensing using satellite measurements would offer the advantage of large spatial coverage with good temporal resolution, even though, due to light limitations, this is only available during the Arctic summer. However, aerosol optical depth (AOD) retrieval over the Arctic region is a great challenge due to the high reflectance of snow and ice and due to the high solar zenith angle. In this article, we describe a retrieval algorithm using Advanced Along-Track Scanning Radiometer (AATSR) data, a radiometer flying on the European Space Agency (ESA) Environmental Satellite (ENVISAT), which offers two views (near nadir and at 55° forward) at seven wavelengths in the visible thermal-infrared (VIS-TIR). The main idea of the Dual-View Multi-Spectral (DVMS) approach is to use the dual view to separate contributions to reflectance measured at the top of the atmosphere (TOA) due to atmospheric aerosol and the underlying surface. The algorithm uses an analytical snow bidirectional reflectance distribution function (BRDF) model for the estimation of the ratio of snow reflectances in the nadir and forward views, as well as an estimate of the atmospheric contribution to TOA reflectance obtained using the dark pixel method over the adjacent ocean surface, assuming that this value applies over nearby land surfaces in the absence of significant sources across the coastline. An iteration involving all four AATSR wavebands in the visible near-infrared (VIS-NIR) is used to retrieve the relevant information. The method is illustrated for AATSR overpasses over Greenland with clear sky in April 2009. Comparison of the retrieved AOD with AErosol Robotic Network (AERONET) data shows a correlation coefficient of 0.75. The AODs retrieved from AATSR using the DVMS approach and those obtained from AERONET data show similar temporal trends, but the AERONET results are more variable and the highest AOD values are mostly missed by the DVMS approach. Limitations of the DVMS method are discussed. The pure-snow BRDF model needs further correction in order to obtain a better estimation for mixtures of snow and ice. © 2013 Copyright 2013 Taylor & Francis.

Particulate matter poses a significant threat to human health. To be able to develop effective mitigation strategies, the origin of particulate matter needs to be established. The regional air quality model LOTOS-EUROS, equipped with a newly developed labeling routine, was used to establish the origin of PM10 and PM2.5 in the Netherlands for 2007-2009 at the source sector level, distinguishing between national and foreign sources. The results suggest that 70-80% of modeled PM10 and 80-95% of PM2.5 in the Netherlands is of anthropogenic origin. About 1/3 of anthropogenic PM10 is of Dutch origin and 2/3 originates in foreign countries. Agriculture and transport are the Dutch sectors with the largest contribution to PM10 mass in the Netherlands, whereas the foreign contribution is more equally apportioned to road transport, other transport, industry, power generation and agriculture. For the PM2.5 fraction, a larger share is apportioned to foreign and anthropogenic origin than for PM10, but the same source sectors are dominant. The national contribution to PM levels is significantly higher in the densely populated Randstad area than for the country on average and areas close to the borders. In general, the Dutch contribution to the concentration of primary aerosol is larger than for secondary species. The sectoral origin varies per component and is location and time dependent. During peak episodes, natural sources are less important than under normal conditions, whereas especially road transport and agriculture become more important. © 2012 Elsevier Ltd.

For risk analysis studies, relatively simple dispersion models are generally applied, such as Gaussian dispersion and dense gas dispersion models. For rail transport risk analyses in the Netherlands, fixed consequence distances are applied for various standard scenarios of hazardous materials releases. The advantage is that the results are uniform and are relatively independent of the party performing the calculations, which facilitates the decision making. The drawback of this method, however, is that the results are mostly (very) conservative and the implementation of safety measures cannot be taken into account. The use of CFD enables to account for local topography of the buildings in a city and additionally enables the investigation of safety measures. This paper describes the use of CFD for a hazardous material release in Tilburg city. The first scenario follows from the standard scenarios for rail transport in the Netherlands as given in guidelines for risk analysis as well as the RBM-II software. The paper describes how the CFD model is set-up for an urban environment and the results are compared to the standard risk analysis scenario. The advantages and disadvantages of both CFD and standard risk analysis methods are discussed. A second scenario is a dense gas release in the same area, which is not part of the standard scenarios. The CFD results for this scenario are compared to wind tunnel experiments.

The Werkendam (WED) and Barendrecht-Ziedewij (BRTZ) gas fields are CO2- and CH4-bearing stratigraphic equivalents in the Netherlands. A comparison in petrographic characteristics and burial histories of the two fields is performed to investigate long-term mineral reactions induced by the presence of CO2. The mineral relations in BRTZ are used as a CO2-free reference for WED. However, the results show that the differences in paragenetic sequence between the two fields are partially due to different temperature evolutions and fluid influxes. The mineral relations that can be linked to the presence of CO2 in WED are the partial dissolution of anhydrite and feldspar and the precipitation of siderite, quartz and potentially minor dolomite. The amount of CO2 sequestered in siderite (and potentially dolomite) is small. PHREEQC geochemical modelling was able to simulate the observations of the mineral reactions induced by carbonized brine. Yet, a sensitivity study on the type of illite used in the model, and the inclusion of minor minerals showed that significantly different reactions can be induced when input parameters are slightly varied. Furthermore the presence and type of Fe-minerals determines if and how much siderite forms. This shows that careful selection of initial mineralogy is required as model input. In one model run mineral reactions were predicted which are known from petrographic studies not to occur under the applied conditions. Hence, besides careful mineral selection, an expert opinion on diagenetic processes is necessary to guide the model towards the proper mineral reactions.

Ensemble Optimization (EnOpt) is a rapidly emerging method for reservoir model based production optimization. EnOpt uses an ensemble of controls to approximate the gradient of the objective function with respect to the controls. Current implementations of EnOpt use a Gaussian ensemble with a constant standard deviation, i.e. a diagonal covariance matrix with entries that remain constant during the optimization process. The Covariance Matrix Adaptation Evolutionary Strategy (CMA-ES) is a gradient-free optimization method, developed in the 'machine learning' community, which also uses an ensemble of controls but with a covariance matrix that is continually updated during the optimization process. It has shown to be an efficient method for several difficult small dimension optimization problems and has recently been applied in the petroleum industry for well location and production optimization. In this study we investigated the scope to improve the computational efficiency of EnOpt through the use of covariance adaptation (CMA-EnOpt). We optimized water flooding of a multi-layer sector model containing multiple sealing and non-sealing faults. The controls used were inflow control valve settings at predefined time intervals for injectors and producers with undiscounted net present value as the objective function. We compared EnOpt and CMA-EnOpt starting from identical covariance matrices. We achieved slightly higher (0.7%-1.8%) objective function values and modest speed-ups with CMA-EnOpt compared to EnOpt, depending on choice of user-defined parameters in both algorithms. However, the major benefit of CMA-EnOpt is its robustness with respect to the initial choice of the covariance matrix. A poor choice of the initial matrix can be detrimental to EnOpt, whereas the CMA-EnOpt performance is near-independent of the initial choice. Copyright 2013, Society of Petroleum Engineers.

Time-lapse seismic data provide information on the dynamics of multiphase reservoir fluid flow in places where no production data from wells are available. This information, in principle, could be used to estimate unknown reservoir properties. However, the amount, resolution, and character of the data have long posed significant challenges for quantitative use in assisted-history- matching workflows. Previous studies, therefore, have generally investigated methods for updating single models with reduced parameter-uncertainty space. Recent developments in ensemble- based history-matching methods have shown the feasibility of multimodel history and matching of production data while maintaining a full uncertainty description. Here, we introduce a robust and flexible reparameterization for interpreted fluid fronts or seismic attribute isolines that extends these developments to seismic history matching. The seismic data set is reparameterized, in terms of arrival times, at observed front positions, thereby significantly reducing the number of data while retaining essential information. A simple 1D example is used to introduce the concepts of the approach. A synthetic 3D example, with spatial complexity that is typical for many water floods, is examined in detail. History-matching cases based on both separate and combined use of production and seismic data are examined. It is shown that consistent multimodel history matches can be obtained without the need for reduction of the parameter space or for localization of the impact of observations. The quality of forecasts based on the history-matched models is evaluated by simulating both expected production and saturation changes throughout the field for a fixed operating strategy. It is shown that bias and uncertainty in the forecasts of production both at existing wells and in the flooded area are reduced considerably when both production and seismic data are incorporated. The proposed workflow, therefore, enables better decisions on field developments that require optimal placement of infill wells. Copyright © 2013 Society of Petroleum Engineers.

Carbon capture and sequestration (CCS) is expected to become a serious CO2-emission reduction technology in the Netherlands. The industry- and government-supported national research programme CATO-2 is tasked to investigate the opportunities and feasibility of CCS projects, both onshore and offshore in the Dutch territory. An example of such opportunities are the deep aquifers and (soon-to-be) depleted gas reservoirs in the mature West

The causes of renewed growth in the atmospheric CH4 burden since 2007 are still poorly understood and subject of intensive scientific discussion. We present a reanalysis of global CH4 emissions during the 2000s, based on the TM5-4DVAR inverse modeling system. The model is optimized using high-accuracy surface observations from NOAA ESRL's global air sampling network for 2000-2010 combined with retrievals of column-averaged CH4 mole fractions from SCIAMACHY onboard ENVISAT (starting 2003).Using climatological OH fields, derived global total emissions for 2007-2010 are 16-20 Tg CH 4/yr higher compared to 2003-2005. Most of the inferred emission increase was located in the tropics (9-14 Tg CH4/yr) and mid-latitudes of the northern hemisphere (6-8 Tg CH4/yr), while no significant trend was derived for Arctic latitudes. The atmospheric increase can be attributed mainly to increased anthropogenic emissions, but the derived trend is significantly smaller than estimated in the EDGARv4.2 emission inventory. Superimposed on the increasing trend in anthropogenic CH4 emissions are significant inter-annual variations (IAV) of emissions from wetlands (up to ±10 Tg CH4/yr), and biomass burning (up to ±7 Tg CH4/yr). Sensitivity experiments, which investigated the impact of the SCIAMACHY observations (versus inversions using only surface observations), of the OH fields used, and of a priori emission inventories, resulted in differences in the detailed latitudinal attribution of CH4 emissions, but the IAV and trends aggregated over larger latitude bands were reasonably robust. All sensitivity experiments show similar performance against independent shipboard and airborne observations used for validation, except over Amazonia where satellite retrievals improved agreement with observations in the free troposphere. Key Points A reanalysis of global CH4 emissions during the 2000s is presented derived global total emissions 2007-2010 16-20 Tg CH4/yr higher than 2003-2005 increase mainly in the tropics and NH mid-latitudes ©2013. American Geophysical Union. All Rights Reserved.

This study is of our particular interest as the quality of our chemical transport model Lotos-Euros can be improved by our understanding of the aerosol-light interaction. In this study we derive aerosol water and chemical composition by a modeling approach that combines in situ measured and remotely sensed aerosol properties with radiosonde measurements of relative humidity. The model simulates water uptake by aerosols based on the chemical composition and size distribution.

The atmospheric concentration of elemental carbon (EC) in Europe during the six-year period 2005-2010 has been simulated with the EMEP MSC-W model. The model bias compared to EC measurements was less than 20% for most of the examined sites. The model results suggest that fossil fuel combustion is the dominant source of EC in most of Europe but that there are important contributions also from residential wood burning during the cold seasons and, during certain episodes, also from open biomass burning (wildfires and agricultural fires). The modelled contributions from open biomass fires to ground level concentrations of EC were small at the sites included in the present study, EC measurements and modelled EC were also compared to optical measurements of black carbon (BC). The relationships between EC and BC (as given by mass absorption cross section, MAC, values) differed widely between the sites, and the correlation between observed EC and BC is sometimes poor, making it difficult to compare results using the two techniques and limiting the comparability of BC measurements to model EC results. A new bottom-up emission inventory for carbonaceous aerosol from residential wood combustion has been applied. For some countries the new inventory has substantially different EC emissions compared to earlier estimates. For northern Europe the most significant changes are much lower emissions in Norway and higher emissions in neighbouring Sweden and Finland. For Norway and Sweden, comparisons to source-apportionment data from winter campaigns indicate that the new inventory may improve model-calculated EC from wood burning. Finally, three different model setups were tested with variable atmospheric lifetimes of EC in order to evaluate the model sensitivity to the assumptions regarding hygroscopicity and atmospheric ageing of EC. The standard ageing scheme leads to a rapid transformation of the emitted hydrophobic EC to hygroscopic particles, and generates similar results when assuming that all EC is aged at the point of emission. Assuming hydrophobic emissions and no ageing leads to higher EC concentrations. For the more remote sites, the observed EC concentration was in between the modelled EC using standard ageing and the scenario treating EC as hydrophobic. This could indicate too-rapid EC ageing in the model in relatively clean parts of the atmosphere. © Author(s) 2013. CC Attribution 3.0 License.

Analysis of siliceous microfossils of a 79 cm long peat sediment core from Highlands Hammock State Park, Florida, revealed distinct changes in the local hydrology during the past 2,500 years. The coring site is a seasonally inundated forest where water availability is directly influenced by precipitation. Diatoms, chrysophyte statospores, sponge remains and phytoliths were counted in 25 samples throughout the core. Based on the relative abundance of diatom species, the record was subdivided into four diatom assemblage zones, which mainly reflect the hydrological state of the study site. An age-depth relationship based on radiocarbon measurements of eight samples reveals a basal age of the core of approximately 2,500 cal. yrs. BP. Two significant changes of diatom assemblage composition were found that could be linked to both, natural and anthropogenic influences. At 700 cal. yrs. BP, the diatom record documents a shift from tychoplanktonic Aulacoseira species to epiphytic Eunotia species, indicating a shortening of the hydroperiod, i. e. the time period during which a wetland is covered by water. This transition was interpreted as being triggered by natural climate change. In the middle of the twentieth century a second major turnover took place, at that time however, as a result of human impact on the park hydrology through the construction of dams and canals close to the study site. © 2011 The Author(s).

Aanvullend onderzoek laat zien dat er binnen steden grote ruimtelijke concentratieverschillen zijn voor roet en zware metalen

In river basins, soils, groundwater, riparian zones and floodplains, streams, rivers, lakes and reservoirs act as successive filters in which the hydrology, ecology and biogeochemical processing are strongly coupled and together act to retain a significant fraction of the nutrients transported. This paper compares existing river ecology concepts with current approaches to describe river biogeochemistry, and assesses the value of these concepts and approaches for understanding the impacts of interacting global change disturbances on river biogeochemistry. Through merging perspectives, concepts, and modeling techniques, we propose integrated model approaches that encompass both aquatic and terrestrial components in heterogeneous landscapes. In this model framework, existing ecological and biogeochemical concepts are extended with a balanced approach for assessing nutrient and sediment delivery, on the one hand, and nutrient in-stream retention on the other hand. © Author(s) 2013. CC Attribution 3.0 License.

A geomechanical modeling study was conducted to investigate stability of major faults during past gas production and future underground gas storage operations in a depleted gas field in the Netherlands. The field experienced induced seismicity during gas production, which was most likely caused by the reactivation of an internal Central fault separating the two major reservoir blocks. A 3D field scale geomechanical finite element model of the gas field was developed with realistic representation of the structural geology and juxtaposition of various lithologies across the Central fault. The model was calibrated to match the subsidence data and the approximate location of the critically stressed, reactivated part of the fault in agreement with the seismological localization of the hypocenters of the past major seismic events. The model predicted a maximum shear slip of up to 2 cm associated with gas production. Additional, but a smaller, fault slip of up to 0.5 cm could be expected during the subsequent phase of cushion gas injection. During annual cycles of gas injection and production, the Central fault is not critically stressed and the predicted stress changes lie in the elastic region. Although the fault slip is unlikely, continuous monitoring of induced seismicity is essential.

This study examines the role of horizontal grid resolution on the performance of the regional three dimensional chemical transport model (CTM) PMCAMx. Two cases were investigated. First, the model was applied over the Northeastern United States with grid resolutions of 36 and 12 km during both a summer and a winter period. In this case the emission inventory was simply interpolated from the low resolution version. In the second case a multi-scale 36/4 km grid resolution is used over Western Europe with high resolution (4 × 4 km) emissions. The improvement in model predictions with the fine grid is modest during the summer and more significant during wintertime at both domains. Major differences are predicted mostly for primary (organics and black carbon (BC)) rather than secondary (e.g. sulfate) species. The use of high grid resolution decreases the bias for BC concentration by more than 30% in the Northeastern US during wintertime. In the Megacity of Paris, using high resolution emissions and a 4-km grid decreases the fractional bias for organic aerosol (OA) from 80% to 60% in the city center and produces much larger spatial concentration gradients in the domain as compared to the emissions being interpolated. These results suggest that future work should combine high grid resolution with high resolution emissions, taking into consideration, though, that the grid resolution is not currently the major source of the discrepancies between model predictions and observations. © 2012 Elsevier Ltd.

The successful surface waves retrieval in solid-Earth seismology using long-time correlations and subsequent tomographic images of the crust have sparked interest in extraction of subsurface information from noise in the exploration seismology. Subsurface information in exploration seismology is usually derived from body-wave reflections > 1 Hz, which is challenging for utilization of ambient noise. We use 11 h of noise recorded in the Sirte basin, Libya. First, we study the characteristics of the noise. We show that the bulk of the noise is composed of surface waves at frequencies below 6 Hz. Some noise panels contain nearly vertically traveling events. We further characterize these events using a beamforming algorithm. From the beamforming, we conclude that these events represent body-wave arrivals with a fairly rich azimuthal distribution. Having body-wave arrivals in the noise is a prerequisite for body-wave reflections retrieval. We crosscorrelate and sum the recorded ambient-noise panels to retrieve common-source gathers, following two approaches - using all the noise and using only noise panels containing body-wave arrivals likely to contribute to the reflections retrieval. Comparing the retrieved gathers with active seismic data, we show that the two-way traveltimes at short offsets of several retrieved events coincide with those of reflections in the active data and thus correspond to apexes of reflections. We then compare retrieved stacked sections of the subsurface from both approaches with the active-data stacked section and show that the reflectors are consistent along a line. The results from the second approach exhibit the reflectors better. © 2013. American Geophysical Union. All Rights Reserved.

Soil nitrogen (N) budgets are used in a global, distributed flow-path model with 0.5° &times 0.5° resolution, representing denitrification and N2O emissions from soils, groundwater and riparian zones for the period 1900-2000 and scenarios for the period 2000-2050 based on the Millennium Ecosystem Assessment. Total agricultural and natural N inputs from N fertilizers, animal manure, biological N2 fixation and atmospheric N deposition increased from 155 to 345 Tg N yr-1 (Tg 1/4 teragram; 1 Tg 1/4 1012 g) between 1900 and 2000. Depending on the scenario, inputs are estimated to further increase to 408-510 Tg N yr21 by 2050. In the period 1900-2000, the soil N budget surplus (inputs minus withdrawal by plants) increased from 118 to 202 Tg yr-1, and this may remain stable or further increase to 275 Tg yr-1 by 2050, depending on the scenario. N2 production from denitrification increased from 52 to 96 Tg yr21 between 1900 and 2000, and N2O-N emissions from 10 to 12 Tg N yr-1. The scenarios foresee a further increase to 142 Tg N2-N and 16 Tg N2O-N yr-1 by 2050. Our results indicate that riparian buffer zones are an important source of N2O contributing an estimated 0.9 Tg N2O-N yr-1 in 2000. Soils are key sites for denitrification and are much more important than groundwater and riparian zones in controlling the N flow to rivers and the oceans. © 2013 The Author(s) Published by the Royal Society. All rights reserved.

The success of shale gas exploration and production in the United States has triggered other countries around the world to look into possibilities of producing gas from different shales. As it turns out, one of the main difficulties when looking for shale gas is obtaining an in depth understanding of the shale formations and interpret where the sweet spots for gas production will be. This is mainly caused by the large differences in properties of shale formations. To improve our understanding of the vertical and lateral property changes that determine high and low productivity zones in shales, TNO has proposed a workflow including well log interpretation, mud log interpretation, depth modeling, organic geochemistry, basin modeling, palynology, electron microscope analyses, mineral typing and porosity identification and characterization. This method serves as a solid basis for sweet spot determination and proper resource estimates. The proposed method has been applied to the two main possible shale gas reservoirs in the Netherlands; the Lower Jurassic Posidonia Shale Formation (PSF) and the Carboniferous (Namurian) Epen Formation. The latter is of particular interest as it contains the highly organic basal Geverik Member (GM). For the two formations detailed and accurate depth maps have been produced. Research on the PSF shows that a number of areas are expected to have reached gas maturity, together around a fifth of the total area of the formation. Besides shale gas there appears to be potential for shale oil. High productivity zones within these shales are expected in the deepest part of formation and orientated along the distribution axis within the West Netherlands Basin. In the multidisciplinary workflow a 3D faciesmodel of the formation is created using palynology and organofacies to detect prospective layers within the formation. This faciesmodel is then used in combination with log-interpretaion, seismic interpretation and sedimentological interpretation to detect most prospective zones and areas. FIB-SEM microscopy shows that coccoliths present in the formation can have large favourable effects on the porosity and permeability providing for a micropermeability pathway for oil and gas when interconnected. When the proposed workflow is applied to the Geverik Member, a correlation between silica content and Total Organic Carbon (TOC) is found, i.e. log-derived TOC is in general close to 10% when the dominant mineral type is silica. Geomechanical analysis of rock properties shows that the lower zone of the Geverik Member is the favourable layer to target, i.e. the layer is dominantly build up of quartz and silica suggesting preferential conditions for hydraulic stimulation.