Abstract: The presence of persistent organic pollutants in Tanzanian environment is not well monitored despite the existing pollution potential from a number of sources. In this study, we investigated for the first time, the concentration profiles of different organohalogen compounds such as organochlorine pesticide residues (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in environmental samples (water and sediments) from the Pangani river basin (PRB). The PRB is one of the largest drainage basins in Tanzania, with its watershed exposed to multiple input sources of trace organic contaminants. Surface water and sediments were sampled from 12 representative stations of diverse characteristics and land-use practices, in three distinct seasons, and extracted by liquidliquid and Soxhlet extraction methods, respectively. Water samples were analyzed by GC-ECD for OCPs only, while sediment samples were analyzed for OCPs, PCBs and PBDEs by GC/MS. Seven compounds, dominated by HCH isomers (5104460 pg/L) and DDT analogs (1601460 pg/L),were detected in the water samples. These concentrations are far below the WHO guidelines for drinking water quality. A total of 42 compounds (8 OCPs, 28 PCB congeners and 6 PBDE congeners) were detected in the sediment samples. Their respective total concentration ranges were 24510,230; 35711,000 and 382175 pg/g dry weight. The spatial distribution patterns and Hierarchical Cluster Analysis reflected the impact of historical agricultural usage in sugarcane plantations (OCPs), and urbanization (PCBs and PBDEs). Risk assessment using sediment quality guidelines indicated no ecotoxicological risks. The results we have found provide preliminary data on levels of the organic contaminants in Pangani river basin as a new insight on the environmental quality of the area.

Abstract: As real-life experimental data on natural ventilation of atmospheric pollution levels in urban street canyons is still scarce and has proven to be complex, this study, experimentally evaluated the impact of an urban street canyon opening on local atmospheric pollution levels, during a 2-week field campaign in a typical urban street canyon in Antwerp, Belgium. Besides following up on atmospheric particulate matter (PM), ultrafine particles (UFPs) and black carbon (BC) levels, the magneto-chemical PM10 composition was quantified to identify contributions of specific elements in enclosed versus open street canyon sections. Results indicated no higher overall PM, UFP and BC concentrations at the enclosed site compared to the open site, but significant day-to-day variability between both monitoring locations, depending on the experienced wind conditions. On days with oblique wind regimes (4 out of 14), natural ventilation was observed at the open location while higher element contributions of Ca, Fe, Co, Ni, Cu, Zn and Sr were exhibited at the enclosed location. Magnetic properties correlated with the PM10 filter loading, and elemental content of Fe, Cr, Mn and Ti. Magnetic bivariate ratios identified finel-grained magnetite carriers with grain sizes below 0.1 μm, indicating similar magnetic source contributions at both monitoring locations. Our holistic approach, combining atmospheric monitoring with magneto-chemical PM characterization has shown the complex impact of real-life wind flow regimes, different source contributions and local traffic dynamics on the resulting pollutant concentrations and contribute to a better understanding on the urban ventilation processes of atmospheric pollution.

Abstract: Purple non‑sulfur bacteria (PNSB) possess significant potential for bioresource recovery from wastewater. Effective operational tools are needed to boost productivity and direct the PNSB biomass towards abundant value-added substances (e.g., protein and co-enzyme Q10, CoQ10). This study aimed to investigate the impact of light, oxygen and volatile fatty acids (VFAs) on PNSB growth (i.e., Rhodobacter sphaeroides) and productivity of protein and CoQ10. Overall, the biomass yields and specific growth rates of PNSB were in the ranges of 0.57–1.08 g biomass g−1 CODremoved and 0.48–0.71 d−1, respectively. VFAs did not influence the biomass yield, yet acetate and VFA mixtures enhanced the specific growth rate with a factor of 1.2–1.5 compared to propionate and butyrate. The most PNSB biomass (1.08 g biomass g−1 CODremoved and 0.71 d−1) and the highest biomass quality (protein content of 609 mg g−1 dry cell weight (DCW) and CoQ10 content of 13.21 mg g−1 DCW) were obtained in the presence of VFA mixtures under natural light and microaerobic (low light alternated with darkness; dissolved oxygen (DO) between 0.5 and 1 mg L−1) conditions (vs. light anaerobic and dark aerobic cultivations). Further investigation on VFAs dynamics revealed that acetate was most rapidly consumed by PNSB in the individual VFA feeding (specific uptake rate of 0.76 g COD g−1 DCW d−1), while acetate as a co-substrate in the mixed VFAs feeding might accelerate the consumption of propionate and butyrate through providing additional cell metabolism precursor. Enzymes activities of succinate dehydrogenase and fructose-1,6-bisphosphatase as well as the concentration of photo pigments confirmed that light, oxygen and VFAs regulated the key enzymes in the energy metabolism and biomass synthesis to boost PNSB growth. These results provide a promising prospect for utilization of fermented waste stream for the harvest of PNSB biomass, protein and CoQ10.

Abstract: The aim of this study is to investigate the dispersion of ultrafine particles and its spatial distribution in a street canyon and its neighbourhood with the 3D CFD model ENVI-met®. The performance of the model at street scale is evaluated and the importance of the boundary conditions like wind field and traffic emissions on the UFP concentration is demonstrated. To support and validate the modelled results, a short-term measurement campaign was conducted in a street canyon in Antwerp, Belgium. The UFP concentration was measured simultaneously with P-TRACK (TSI Model 8525) at four different locations in the canyon. The modelled UFP concentrations compare well with the measured data (correlation coefficient R from 0.44 to 0.93) within the standard deviation of the measurements. Despite the moderate traffic flow in the street canyon, UFP concentrations in the canyon are in general double of the background concentrations, indicating the high local contribution for this particle number concentration. Some of the observed concentration profiles are not resembled by the model simulations. For these specific anomalies, further analysis is performed and plausible explanations are put forward. The role of wind direction and traffic emissions is investigated. The performance evaluation of ENVI-met® shows that in general the model qualitatively and quantitatively describes the dispersion of UFP in the street canyon study.

Abstract: Green infrastructure (GI) is already known to be a suitable way to enhance air quality in urban environments. Living wall systems (LWS) can be implemented in locations where other forms of GI, such as trees or hedges, are not suitable. However, much debate remains about the variables that influence their particulate matter (PM) accumulation efficiency. This study attempts to clarify which plant species are relatively the most efficient in capturing PM and which traits are decisive when it comes to the implementation of a LWS. We investigated 11 plant species commonly used on living walls, located close to train tracks and roads. PM accumulation on leaves was quantified by magnetic analysis (Saturation Isothermal Remanent Magnetization (SIRM)). Several leaf morphological variables that could potentially influence PM capture were assessed, as well as the Wall Leaf Area Index. A wide range in SIRM values (2.74–417 μA) was found between all species. Differences in SIRM could be attributed to one of the morphological parameters, namely SLA (specific leaf area). This suggest that by just assessing SLA, one can estimate the PM capture efficiency of a plant species, which is extremely interesting for urban greeners. Regarding temporal variation, some species accumulated PM over the growing season, while others actually decreased in PM levels. This decrease can be attributed to rapid leaf expansion and variations in meteorology. Correct assessment of leaf age is important here; we suggest individual labeling of leaves for further studies. Highest SIRM values were found close to ground level. This suggests that, when traffic is the main pollution source, it is most effective when LWS are applied at ground level. We conclude that LWS can act as local sinks for PM, provided that species are selected correctly and systems are applied according to the state of the art.

Abstract: A soil history of exposure to extreme weather may impact future plant growth and microbial community assembly. Currently, little is known about whether and how previous precipitation regime (PR)-induced changes in soil microbial communities influence plant and soil microbial community responses to a subsequent PR. We exposed grassland mesocosms to either an ambient PR (1 day wet-dry alternation) or a persistent PR (30 days consecutive wet-dry alternation) for one year. This conditioned soil was then inoculated as a 10 % fraction into 90 % sterilized “native” soil, after which new plant communities were established and subjected to either the ambient or persistent PR for 60 days. We assessed whether past persistent weather-induced changes in soil microbial community composition affect soil microbial and plant community responses to subsequent weather persistence. The historical regimes caused enduring effects on fungal communities and only temporary effects on bacterial communities, but did not trigger soil microbial legacy effects on plant productivity when exposed to either current PR. This study provides experimental evidence for soil legacy of climate persistence on grassland ecosystems in response to subsequent climate persistence, helping to understand and predict the influences of future climate change on soil biota.

Abstract: The tetravalent and hexavalent selenium content of water samples can be determined by conventional energy-dispersive X-ray fluorescence after different preconcentration steps. Selenium values of nearly three-hundred different environmental and drinking water samples in Belgium are reported. The results are quite low, ranging from the detection limits up to 1 μg l−1. The concentration levels are compared to literature data and the speciation is discussed. The contribution of drinking water to the daily intake of selenium in Belgium ranges from less than 0.2 to 5%.

Abstract: Agricultural practices enhancing soil organic carbon (SOC) show potential to buffer negative effects of climate change on forage grass performance. We tested this by subjecting five forage grass varieties differing in fodder quality and drought/flooding resistance to increased persistence in summer precipitation regimes (PR) across sandy and sandy-loam soils from either permanent (high SOC) or temporary grasslands (low SOC) in adjacent parcels. Over the course of two consecutive summers, monoculture mesocosms were subjected to rainy/dry weather alternation either every 3 days or every 30 days, whilst keeping total precipitation equal. Increased PR persistence induced species-specific drought damage and productivity declines. Soils from permanent grasslands with elevated SOC buffered plant quality, but buffering effects of SOC on drought damage, nutrient availability and yield differed between texture classes. In the more persistent PR, Festuca arundinacea FERMINA was the most productive species but had the lowest quality under both ample water supply and mild soil drought, whilst under the most intense soil droughts, Festulolium FESTILO maintained the highest yields. The hybrid Lolium × boucheanum kunth MELCOMBI had intermediate productivity and both Lolium perenne varieties showed the lowest yields under soil drought, but the highest forage quality (especially the tetraploid variety MELFORCE). Performance varied with plant maturity stage and across seasons/years and was driven by altered water and nutrient availability and related nitrogen nutrition among species during drought and upon rewetting. Moreover, whilst permanent grassland soils showed the most consistent positive effects on plant performance, their available water capacity also declined under increased PR persistence. We conclude that permanent grassland soils with historically elevated SOC likely buffer negative effects of increasing summer weather persistence on forage grass performance, but may also be more sensitive to degradation under climate change.

Abstract: Large river catchments with mixed land use capture pesticides from many sources, and degradable pesticides are converted during downstream transport. Unravelling the contribution of pesticide source and the effect of degradation processes is a challenge in such areas. However, insight and understanding of the sources is important for targeted managen-lent, especially when water is abstracted from the river for drinking water production. The river Meuse is such a case. A long-term monitoring data set was applied in a modelling approach for assessing the contribution of waste water treatment plants (WWTPs) and tributaries (sub-basins) to surface water contamination, and to evaluate the effect of decay on the downstream concentrations of glyphosate and AMPA at the point of drinking water abstraction. The results show that WWTPs are important contributors for glyphosate and AMPA in large river catchments with mixed land uses. In the studied area, the river Meuse in the Netherlands, the relative contribution of WWTP effluents is above 29% for glyphosate and around 12% for AMPA. Local industries are found to be potentially big contributors of AMPA. Glyphosate entering the river system is gradually converted to AMPA and other degradation-productions, which results in downstream loads that are considerably lower than the sum of all influxes. In summer when the travel time is longer due to lower discharge, the first order decay of glyphosate in the river Meuse is estimated to result in about 50% reduction of the downstream glyphosate concentrations over a river stretch of 250 km. The contribution of glyphosate decay to the observed AMPA concentrations ranges between 2% and 10%. Contributions are sensitive to seasonal variations in discharge that influence the concentrations through dilution and degradation. (C) 2016 Elsevier B.V. All rights reserved.

Abstract: The ability of urban wastewater systems to adapt and transform as a response to change is an integral part of sustainable development. This requires technology and infrastructure that can be adapted to new operational challenges. In this study the adaptive capacity of urban wastewater systems is evaluated by assessing the interdependencies between system components. In interdependent and therefore tightly coupled systems, changes to one systems component will require alteration elsewhere in the system, therefore impairing the capacity of these systems to be changed. The aim of this paper is to develop a methodology to evaluate the adaptive capacity of urban wastewater systems by assessing how change drivers and innovation affect existing wastewater technology and infrastructure. The methodology comprises 7 steps and applies a change impact table and a design structure matrix that are completed by experts during workshops. Change impact tables quantify where change drivers, such as energy neutrality and resource recovery, require innovation in a system. The design structure matrix is a tool to quantify emerging changes that are a result of the innovation. The method is applied for the change driver of energy neutrality and shown for two innovations: a decentralised upflow anaerobic sludge blanket reactor followed by an anammox process and a conventional activated sludge treatment with enhanced chemical precipitation and high temperature-high pressure hydrolysis. The results show that the energy neutrality of wastewater systems can be address by either innovation in the decentralised or centralised treatment. The quantification of the emerging changes for both innovations indicates that the decentralised treatment is more disruptive, or in other words, the system needs to undergo more adaptation. It is concluded that the change impact and change propagation method can be used to characterise and quantify the technological or infrastructural transformations. In addition, it provides insight into the stakeholders affected by change.

Abstract: The state-of-the-science in sustainability assessment of soil and groundwater remediation is evaluated with the application of four decision support systems (DSSs) to a large-scale brownfield revitalization case study. The DSSs were used to perform sustainability appraisals of four technically feasible remediation alternatives proposed for the site. The first stage of the review compares the scope of each tool's sustainability indicators, how these indicators are measured and how the tools differ in terms of standardization and weighting procedures. The second stage of the review compares the outputs from the tools and determines the key factors that result in differing results between tools. The evaluation of indicator sets and tool structures explains why the tools generate differing results. Not all crucial impact areas, as identified by sustainable remediation forums, are thoroughly considered by the tools, particularly with regard to the social and economic aspects of sustainability. Variations in boundary conditions defined between technologies, produce distorted environmental impact results, especially when in-situ and ex-situ technologies are compared. The review draws attention to the need for end users to be aware of which aspects of sustainability are considered, how the aspects are measured and how all aspects are ultimately balanced in the evaluation of potential remediation strategies. Existing tools can be improved by considering different technologies within the same boundary conditions and by expanding indicator sets to include indicators deemed to be relevant by remediation forums. (C) 2013 Elsevier B.V. All rights reserved.