Abstract: Dry deposition is an important process determining pollutant concentrations, especially when studying the influence of urban green infrastructure on particulate matter (PM) levels in cities. Computational fluid dynamics (CFD) models of PM capture by vegetation are useful tools to increase their applicability. The meso-scale models of Zhang et al. (Atmos Environ 35:549-560, 2001) and Petroff and Zhang (Geosci Model Dev 3(2):753-769, 2010) have often been adopted in CFD models, however a comparison of these models with measurements including all PM particle sizes detrimental to health has been rarely reported and certainly not for green wall species. This study presents dry deposition experiments on real grown Hedera helix in a wind tunnel setup with wind speeds from 1 to 4 m s(-1) and PM consisting of a mixture of soot (0.02 – 0.2 mu mu m) and dust particles (0.3 – 10 mu mu m). Significant factors determining the collection efficiency (%) were particle diameter and wind speed, but relative air humidity and the type of PM (soot or dust) did not have a significant influence. Zhang's model outperformed Petroff's model for particles < 0.3 mu mu m, however the inclusion of turbulent impaction in Petroff's model resulted in better agreement with the measurements for particles > 2 – 3 mu mu m. The optimised model had an overall root-mean-square-error of similar to 4% for collection efficiency (CE) and 0.4 cm s-1 for deposition velocity (nu d), which was shown to be highly competitive against previously described models. It can thus be used to model PM deposition on other plant species, provided the correct parameterisation of the drag by this species. A detailed description of the spatial distribution of the vegetation could solve the underestimation for particle sizes of 0.3 – 2 mu mu m.

Abstract: Groundwater fluxes in tidal marshes largely control key ecosystem functions and services, such as vegetation growth, soil carbon sequestration, and nutrient cycling. In tidal marshes restored on formerly embanked agricultural land, groundwater fluxes are often limited as compared to nearby natural marshes, as a result of historical agricultural soil compaction. To improve the functioning of restored tidal marshes, knowledge is needed on how much certain design options can optimize soil-groundwater interactions in future restoration projects. Based on measured data on soil properties and tidally induced groundwater dynamics, we calibrated and evaluated a 2D vertical model of a creek-marsh cross-section, accounting for both saturated and unsaturated groundwater flow and solute transport in a variably saturated groundwater flow model. We found that model simulations of common restoration practices such as soil amendments (increasing the depth of porous soil on top of the compact layer) and creek excavation (increasing the creek density) increase the soil aeration depth and time, the drainage depth and the solute flux, and decrease the residence time of solutes in the porewater. Our simulations indicate that increasing the depth to the compact layer from 20 cm to 40 cm, or increasing the creek density from 1 creek to 2 creeks along a 50 m marsh transect (while maintaining the total creek cross-sectional area), in both cases more than doubles the volume of water processed by the marsh soil. We discuss that this may stimulate nutrient cycling. As such, our study demonstrates that groundwater modelling can support the design of marsh restoration measures aiming to optimize groundwater fluxes and related ecosystem services.

Abstract: We investigate a Josephson junction in an electron-hole superfluid in a double-layer transition metal dichalco-genide heterostructure. The observation of a critical tunneling current is a clear signature of superfluidity. In addition, we find the BCS-BEC crossover physics in the narrow barrier region controls the critical current across the entire system. The corresponding critical velocity, which is measurable in this system, has a maximum when the excitations pass from bosonic to fermionic. Remarkably, this occurs for the density at the boundary of the BEC to BCS-BEC crossover regime determined from the condensate fraction. This provides, in a semiconductor system, an experimental way to determine the position of this boundary.

Abstract: Methamphetamine (MA) is a synthetic psychoactive drug which is consumed both licitly and illicitly. In some countries it is prescribed for attention-deficit and hyperactivity disorder, and short-term treatment of obesity. More often though, it is abused for its psychostimulant properties. Unfortunately, the spread and abuse of this synthetic drug have increased globally, being reported as the most widely consumed synthetic psychoactive drug in the world in 2019. Attempting to overcome the shortcomings of the currently used on-site methods for MA detection in suspected cargos, the present study explores the potential of electrochemical identification of MA by means of square wave voltammetry on disposable graphite screen-printed electrodes. Hence, the analytical characterization of the method was evaluated under optimal conditions exhibiting a linear range between 50 mu M and 2.5 mM MA, a LOD of 16.7 mu M, a LOQ of 50.0 mu M and a sensitivity of 5.3 mu A mM-1. Interestingly, two zones in the potential window were identified for the detection of MA, depending on its concentration in solution. Furthermore, the oxidative pathway of MA was elucidated employing liquid chromatography – mass spectrometry to understand the change in the electrochemical profile. Thereafter, the selectivity of the method towards MA in mixtures with other drugs of abuse as well as common adulterants/cutting agents was evaluated. Finally, the described method was employed for the analysis of MA in confiscated samples and compared with forensic methods, displaying its potential as a fast and easy-to-use method for on-site analysis.

Abstract: The risk profile of Cr and Pb in urban road deposited sediment Exponential urbanisation and industrial growth occur on a global scale and result in an ecological burden, of which one important part is pollution. It is well known that the extent of air pollution has escalated over the past two decades in several parts of the world, despite mitigating measures and legislation. Current research points to the fact that air pollution in urban and industrial areas is substantially different from that found in rural areas. Road dust (RD) contributes up to 35% of airborne particulate matter due to resuspension thereof, and poses a health concern due to carcinogenic and toxic components potentially present in the micron-sized fractions. Although literature does report on the concentrations of trace, toxic metals and metalloids present in RD (Hooker and Nathanail 2006), the molecular make-up of particulates generated due to the resuspension of the RD is not well documented. In vitro and animal toxicological studies have confirmed that the chemical composition of inhaled particles plays a major role in its toxic, genotoxic and carcinogenic mechanisms, but the component-specific toxic effects are still not understood. Transition metals binding to air particle matter can result in reactive oxygen species in the human body (particularly in the lungs), and this is a significant risk, especially for vulnerable population groups like elderly people, children and terminally ill patients. The characterisation of the molecular composition of the fine fraction is evidently of importance for public health. During an earlier study, road dust from an inner-city environment in the UK was collected and partially characterised (Barrett e.a. 2010). These same-size fractions were analysed for their elemental concentrations, using X-ray Fluorescence Spectrometry (XRFS) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). In addition, single-particle analysis was performed on the different fractions by means of Computer Controlled Electron Probe X-ray Micro Analysis (CC-EPXMA) and their molecular structure probed by studying elemental associations. These findings were correlated with Micro Raman Spectroscopy (MRS) results. It was found that the fine fraction (<38 μm) had the highest Pb (238 ppm) and Cr (171 ppm) concentrations. The CC-EPXMA data showed >50% association of Cr-rich particles with Pb and the MRS data showed that the Cr was mostly present as lead chromate and therefore in the Cr(VI) oxidation state. Concentrations of both Pb and Cr decreased substantially (279 (<38 mm) 13 ppm (<1mm); 171 (<38 mm) 91 ppm (<1mm) respectively) in the larger fractions. Apart from rather alarmingly high concentrations of oxidative stressors (Cu, Fe, Mn), the carcinogenic and toxic potential of the inhalable fraction is evident. Preliminary bioaccessibility data indicated that both Cr and Pb are readily

Abstract: Single cell protein (SCP), or originally named microbial protein, is the edible microbial biomass derived from e.g. microalgae, bacteria and fungi, which can be used as protein sources replacing conventional protein sources for animal feed or human food such as fishmeal and soybean (Anupama & Ravindra 2000). SCP presents great potential as protein supplement to alleviate the problem of food scarcity in the future (Nasseri et al. 2011). In general, microalgae as SCP contains above 50% protein over dry weight and specifically for the marine microalgae Dunaliella salina the amount stays around 57% (Becker 2007). Commercially the most common system for Dunaliella sp. production is the outdoor open pond, thus the microalgal cells are subjected to a natural light/dark cycle (Hosseini Tafreshi & Shariati 2009). Being photo-autotrophic microorganisms, the lack of light energy sources is a risk leading to night biomass loss (Ogbonna & Tanaka 1996). On the other hand, for some microalgae species cell division occurs primarily during the night suggesting its night protein synthesis (Cuhel et al. 1984). As a consequence, day and night metabolisms of microalgae introduced by light/dark cycles potentially will have big impacts on the biomass development, both in growth and biochemical composition. In this study, the effect of the light/dark cycle on the growth and protein synthesis of Dunaliella salina was explored in comparison with continuous light cultivation.

Abstract: By 2050, the world population will have considerably expanded and the life standard of many will increase, yielding a 50% higher demand in protein (FAO, 2011), and even increases of 82 and 102% for diary and meat products, respectively (Boland et al., 2013). To provide in this increasing demand we are highly dependent on our classical fertilizer to food chain which has a high environmental impact and lacks efficiency. Nutrient losses cause eutrophication and biodiversity loss and the input of resources is already beyond the boundaries of environmental sustainability (Steffen et al., 2015). Phosphate fertilizers are made from phosphate rock (apatite), of which the reserves are predicted to be depleted within 50 100 years if we continue business as usual (Cordell et al., 2009). Next to problems related to the unbalanced geopolitical distribution with dominance in China and Morocco, the decreasing quality of the remaining apatite will result in an increasing environmental impact of fertilizer production. Finally, our traditional food production model requires 30% of all ice-free land, 70% of all available freshwater and produces up to one third of the global greenhouse gas emission, of which 80 to 86% is linked to agricultural production (Vermeulen et al., 2012). To ensure food security, nutrient recovery from waste streams can provide an important strategy. In this context, struvite ( ) crystallisation may be applied to recover phosphorus, along with some nitrogen. Reusing these nutrients as agricultural fertilizer on the field will lead to considerable losses to the environment. In contrast, their use to cultivate micro-organisms, e.g. for single cell protein (SCP), offers to potential of a near perfect conversion efficiency (Moed et al., 2015). At this moment, microalgae represent the most developed type of SCP, and are a promising protein source due to their growth rate, high nutritional quality and extremely high nutrient usage efficiency (Becker, 2007). Reliable solubilisation data are essential to design a technological strategy for struvite dosage in bioreactors for SCP production. The effect on solubility and solubilisation rate of relevant physicochemical parameters was studied experimentally in aqueous solutions. Because pH and temperature greatly affect solubilisation kinetics they were set at a constant value of 7 and 20°C respectively. The effect of some parameters on struvite solubility was already studied (Bhuiyan et al., 2007; Ariyanto et al., 2014; Roncal-Herrero and Oelkers, 2011), but solubilisation rates were not yet considered and pH was not controlled at a constant value. The chemical parameters considered in this study include the concentration of different common ions ( and ), foreign ions ( and the chelating agent ethylenediaminetetraacetic acid, EDTA) present in micro-algal cultivation media as well as ionic strength (as set by NaCl). The main physical parameter included was contact surface, through variation in initial particle size and as well as in struvite dosage concentration.