Modified Fenton reaction for trichlorophenol dechlorination by enzymatically generated H2O2 and gluconic acid chelate

Glucose oxidase is a well-known enzyme that catalyzes the oxidation of β-d-glucose to produce gluconic acid and hydrogen peroxide. Fenton reaction is a powerful oxidation technology used for the oxidation of groundwater pollutants. For the application of Fenton reaction in groundwater remediation, successful operation of Fenton reaction near neutral pH, and on-site generation of both H₂O₂ and chelate will be beneficial. The focus of this experimental study was to couple the glucose oxidation reaction with chelate-based Fenton reaction. The idea was to use the hydrogen peroxide and chelate gluconic acid generated during glucose oxidation for the dechlorination of 2,4,6-trichlorophenol (TCP) by Fenton reaction. The oxidation of glucose was achieved using the enzyme in free and immobilized forms. The rate of production of hydrogen peroxide was determined for each system, and was used to estimate the time required for complete consumption of glucose during the process, thus avoiding any traces of glucose in the Fenton reaction. In the case of free enzyme reaction, separation of the enzyme was achieved using an ultrafiltration membrane before initiating the Fenton reaction. The oxidation of TCP by Fenton reaction was performed at varying ratios of gluconic acid/Fe, and its effect on the decomposition of TCP and H₂O₂ was studied. TCP degradation was studied both in terms of parent compound degradation and free chloride generation.     

An investigation on the physical,chemical and ecotoxicological characteristics of particulate matter emitted from light-duty vehicles

Particulate matter (PM) emitted from three light-duty vehicles was studied in terms of its physicochemical and ecotoxicological character using Microtox^® bioassay tests. A diesel vehicle equipped with an oxidation catalyst emitted PM which consisted of carbon species at over 97%. PM from a diesel vehicle with a particle filter (DPF) consisted of almost equal amounts of carbon species and ions, while a gasoline vehicle emitted PM consisting of ～90% carbon and ～10% ions. Both the DPF and the gasoline vehicles produced a distinct nucleation mode at 120 km/h. The PM emitted from the DPF and the gasoline vehicles was less ecotoxic than that of conventional diesel, but not in direct proportion to the emission levels of the different vehicles. These results indicate that PM emission reductions are not equally translated into ecotoxicity reductions, implying some deficiencies on the actual environmental impact of emission control technologies and regulations.     

Can renewable energy technologies improve the management of stressed water resources threatened by climate change? Argentine drylands case study

This work addresses increasing concerns about water management for rural productive activities in the vast dry regions of Latin America by assessing renewable energy technologies (RETs) that could be suitable for localized needs. Forecasted trends in climate change and variability make this analysis very relevant, in an area where very little published work exists. While Argentina is widely known for its fertile pampas, around 75 % of the country consists of dry lands. In addition, erosion is increasing by up to 650,000 hectares each year. The coordinated adoption of a set of actions, including land use planning and strengthening productive activities that guarantee access to water and improve water and soil management is needed. Renewable energies could help towards achieving these aims, if water is made available at affordable costs and with suitable technologies. This paper evaluates experiences with three RETs—photovoltaic pumping from deep wells, small wind turbine pumping, and high-power wind turbines, and discusses a potential role for use in rural Argentina. Although cheaper and more reliable renewable alternatives to energy sources such as diesel could be used for pumping from groundwater resources in isolated locations, limitations arise when pumping head and/or water volume requirements are large or highly seasonal. The cost increases and technical challenges of accessing this deeper water, as indicated by case studies, emphasize the importance of planning and support schemes development.     

Advancing to a Circular Economy: three essential ingredients for a comprehensive policy mix

Material resources exploitation and the pressure on natural ecosystems have raised concerns over potential future resource risks and supply failures worldwide. Interest in the concept of Circular Economy has surged in recent years among policy makers and business actors. An increasing amount of literature touches upon the conceptualisation of Circular Economy, the development of ‘circular solutions’ and circular business models, and policies for a Circular Economy. However, relevant studies on resource efficiency policies mostly utilise a case-by-case or sector-by-sector approach and do not consider the systemic interdependencies of the underlying operational policy framework. In this contribution, a mapping of the existing resource policy framework in the European Union (EU) is undertaken, and used as a basis for identifying policy areas that have been less prominent in influencing material resource efficiency. Employing a life cycle approach, policies affecting material efficiency in the production and consumption stages of a product have been found to be poorly utilised so far in the EU. Taking this as a point of departure, three policy areas that can contribute to closing material loops and increasing resource efficiency are thoroughly discussed and their application challenges are highlighted. The three policy areas are: (1) policies for reuse, repair and remanufacturing; (2) green public procurement and innovation procurement; and (3) policies for improving secondary materials markets. Finally, a potential policy mix, including policy instruments from the three mentioned policy areas—together with policy mixing principles—is presented to outline a possible pathway for transitioning to Circular Economy policy making.     

Coastal dune development and morphological changes along the littorals of Garigliano,Italy, and Elis,Greece, during the Holocene

Geomorphological and sedimentological studies were carried out along the Garigliano and Elis littorals with the aim to highlight if similar geoenvironmental features are controlled by same coastal processes. Actually, both sites are in Mediterranean climate regions very far each other, modeled by western winds and storms, characterized by wide sandy coastal dunes parallel to the present shoreline, with abundant pumices, and locally anthropized. The Garigliano littoral is characterized by Holocene dune and Pleistocene aeolian deposits. The beach is bounded landwards by a dune system emplaced during the Holocene. Geoarchaeological surveys highlighted the presence of a Roman road which cut the dune, with age older than Graeco-Roman Period. Since the end of the 1950’s, strong littoral retreat affected the beach-dune system, partly due to human activity. The coastland of Elis is characterized by Quaternary marine deposits. Three significant morphogenetic phases occurred during the Holocene. During the last phase, from Graeco-Roman Period to current, shoreline retreat and deposition of aeolian sands occurred. Geoarchaeological evidences suggest that this phase is related to a sea-level lowstand followed by a slow sea-level rise up to the present position, and by humid-temperate climate. Geomorphological surveys of the dunes of Garigliano and Elis, each other compared, suggest that the main phases of their development are related to the effects of climatic conditions, sea-level changes, and secondly to the recent anthropization. The coarse pumices found on both beaches of Campania and Peloponnese regions show the same mineralogical and petrographic features, so we assumed that they likely originated from the Aeolian Arc, southern Italy, which have same composition. These pumices reached the studied coasts by flotation, under the influence of winds and marine surface currents from the southwest-southeast and northwest-west respectively, participating to local coastal processes and representing a good geoindicator of long-distance drift. Precisely for these morphologically converging aspects, such distant sites have been selected and compared.     

A Day/Night Box Model for Prescribed Burning Impact in Willamette Valley,Oregon

The relationship between daily total tons of forestry fuel consumed by prescribed burns in western Oregon and 24-hour average total suspended participate (TSP) concentration in the Willamette Valley is examined. The relationship is statistically significant at the 95 % level. A simple physical model is in agreement with the statistical relationships. The effect of western Oregon prescribed burning on mean TSP loadings in rural Willamette Valley over periods of a month or more may be estimated with good confidence with a factor of 2 accuracy.     

The potential of a partial-flow constant dilution ratio sampling system as a candidate for vehicle exhaust aerosol measurements

This paper presents the measurement of airborne particle properties with use of a dedicated sampling protocol and a measurement setup directly installed in the exhaust line of vehicles and engines. The sampling system dilutes a small part of the exhaust directly at the tailpipe without the need of exhaust gas transfer lines that may lead to sampling artifacts. Dilution takes place in two steps with a primary dilution ratio universally set at a value of 12.5:1 for all vehicles and engines tested, and subsequent dilution steps reducing particle concentration within the measuring range of the instruments used. Dilution air temperature and residence time were set at 32 degrees C and 2.5 sec respectively, to allow repeatable measurement of nucleation-mode particles. The paper summarizes the specifications of the system, evaluates its performance in comparison to real-world dilution (chasing experiments), and presents the repeatability and reproducibility of measurements performed in different laboratories. In general, after taking precautions for the setup and condition of instruments, both measurement quality indices reached levels similar to the measurement of particulate matter (PM) mass. Application of the system, using the same protocol, to measure many light-duty vehicles and engines is finally demonstrated, providing useful conclusions for the emission performance of different sized engines. The study concludes that the use of partial-flow sampling systems may offer advantages for the measurement of particle emissions from low-emission engines compared with constant volume sampling facilities, including lower cost of purchase and operation, versatility, lack of artifacts, and possibilities for standardization in different environments.     

Validation of road vehicle and traffic emission models – A review and meta-analysis

Road transport is often the main source of air pollution in urban areas, and there is an increasing need to estimate its contribution precisely so that pollution-reduction measures (e.g. emission standards, scrapage programs, traffic management, ITS) are designed and implemented appropriately. This paper presents a meta-analysis of 50 studies dealing with the validation of various types of traffic emission model, including ‘average speed’, ‘traffic situation’, ‘traffic variable’, ‘cycle variable’, and ‘modal’ models. The validation studies employ measurements in tunnels, ambient concentration measurements, remote sensing, laboratory tests, and mass-balance techniques. One major finding of the analysis is that several models are only partially validated or not validated at all. The mean prediction errors are generally within a factor of 1.3 of the observed values for CO₂, within a factor of 2 for HC and NO_x, and within a factor of 3 for CO and PM, although differences as high as a factor of 5 have been reported. A positive mean prediction error for NO_x (i.e. overestimation) was established for all model types and practically all validation techniques. In the case of HC, model predictions have been moving from underestimation to overestimation since the 1980s. The large prediction error for PM may be associated with different PM definitions between models and observations (e.g. size, measurement principle, exhaust/non-exhaust contribution).Statistical analyses show that the mean prediction error is generally not significantly different (p < 0.05) when the data are categorised according to model type or validation technique. Thus, there is no conclusive evidence that demonstrates that more complex models systematically perform better in terms of prediction error than less complex models. In fact, less complex models appear to perform better for PM. Moreover, the choice of validation technique does not systematically affect the result, with the exception of a CO underprediction when the validation is based on ambient concentration measurements and inverse modelling. The analysis identified two vital elements currently lacking in traffic emissions modelling: 1) guidance on the allowable error margins for different applications/scales, and 2) estimates of prediction errors. It is recommended that current and future emission models incorporate the capability to quantify prediction errors, and that clear guidelines are developed internationally with respect to expected accuracy.     

Environmental PCBs in Guánica Bay,Puerto Rico: implications for community health

Guánica Bay, located in southwestern Puerto Rico, has suffered oil spills and other pollution discharges since the 1960s. Previous research showed elevated concentrations of polychlorinated biphenyls (PCBs) in coral reef and sediment. This research examined PCB concentrations in sediment and fish. Sediment and fish sampling in the bay was facilitated by community members. This study identified the second highest reported PCB level (129,300 ng/g) in sediment in the USA. Fish samples also showed elevated concentrations (1623 to 3768 ng/g), which were higher than the thresholds of safe levels of PCBs in fish for human consumption. The alarmingly high concentration of PCBs calls for proactive community engagement to bring awareness about contamination of the bay and more extensive sampling to test for the concentration of PCBs in seafood and the people of Guánica. This study also underscores the value of the involvement of local communities during sampling design aimed at identifying hot spots of contaminants.     

Diesel passenger car PM emissions: From Euro 1 to Euro 4 with particle filter

This paper examines the impact of the emission control and fuel technology development on the emissions of gaseous and, in particular, PM pollutants from diesel passenger cars. Three cars in five configurations in total were measured, and covered the range from Euro 1 to Euro 4 standards. The emission control ranged from no aftertreatment in the Euro 1 case, an oxidation catalyst in Euro 2, two oxidation catalysts and exhaust gas recirculation in Euro 3 and Euro 4, while a catalyzed diesel particle filter (DPF) fitted in the Euro 4 car led to a Euro 4 + DPF configuration. Both certification test and real-world driving cycles were employed. The results showed that CO and HC emissions were much lower than the emission standard over the hot-start real-world cycles. However, vehicle technologies from Euro 2 to Euro 4 exceeded the NOx and PM emission levels over at least one real-world cycle. The NOx emission level reached up to 3.6 times the certification level in case of the Euro 4 car. PM were up to 40% and 60% higher than certification level for the Euro 2 and Euro 3 cars, while the Euro 4 car emitted close or slightly below the certification level over the real-world driving cycles. PM mass reductions from Euro 1 to Euro 4 were associated with a relevant decrease in the total particle number, in particular over the certification test. This was not followed by a respective reduction in the solid particle number which remained rather constant between the four technologies at 0.86 × 10¹⁴ km^?1 (coefficient of variation 9%). As a result, the ratio of solid vs. total particle number ranged from ～50% in Euro 1–100% in Euro 4. A significant reduction of more than three orders of magnitude in solid particle number is achieved with the introduction of the DPF. However, the potential for nucleation mode formation at high speed from the DPF car is an issue that needs to be considered in the over all assessment of its environmental benefit. Finally, comparison of the mobility and aerodynamic diameters of airborne particles led to fractal dimensions dropping from 2.60 (Euro 1) to 2.51 (Euro 4), denoting a more loose structure with improving technology.