Low Pollutant Concentrations Research Articles

Analysis of patterns of urban sprawl and surface urban heat island in solan town of himachal pradesh using remote sensing and gis

Rapid unplanned urbanization consequently influencing the land surface temperature globally that lead to Urban Heat Island (UHI) phenomenon that has negative impact on the quality of life of population exist within that area. Impervious surfaces effect the functioning of ecosystem that’s why urban monitoring is important. Present study was focused on detection of presence of the UHI phenomenon in the Solan town of Himachal Pradesh (H.P.) from year 1990, 2000, 2010 and 2020. Multitemporal analysis is performed to analyze trend of temperature using Landsat 5, 7 and 8 thermal infrared sensors processed within Geographical Information System (GIS). Google Earth engine also used as a platform for the detection of urban sprawl with the help of classified map extracted from it. R software used for the detection of fragmentation and other landscape indices on the classified map. Region of interests (ROIs) was created in the urban and surrounding rural area to analyze the difference in temperature and landscape metrics in both of ROIs. Study highlighted the presence of Surface Urban Heat Island (SUHI) phenomenon in the medium size town of Solan in all the decades with the maximum LST difference of 1.92°C in year 1990, 0.68°C in year 2000, 1.02°C in year 2010 and 2.12°C in year 2020 between the two ROIs. Temperature values in year 2020 has declined due to reforestation in the area and the consequence of global pandemic lead to change in temperature due to lower pollutant concentration. LST variation indicate a rise of 4.61°C in the minimum and 9.19°C in the maximum temperature from 1990 to 2010. Urban sprawl has been reported, the urban expansion was maximum from year 1990 to 2000 in the Centre of city with the percentage of 31.27 km2 while total rate of change in urban surfaces is 131.48km2 which includes rural area along with road has been converted in impervious surface with the passage of years. Overall accuracy of the classified maps was 88%. The classified maps indicate correlation of landscape indices with the urban expansion of town where heterogeneity significantly increased with time whereas patch number and density is increasing with the urban growth and declining with reforestation in the urban and rural ROIs it fluctuate accordingly. This study reported the need of effective and sustainable urban planning method in the developing cities of Himalayas. Policy makers should introduce green spaces and plantation in urban area to mitigate the UHI phenomenon in future.

Air Quality Versus Perceived Comfort and Health in Office Buildings at Western Macedonia Area, Greece during the Pandemic Period

This study investigated the indoor environment quality (IEQ) of eight office buildings of interest due to: (a) their location at the region of Western Macedonia, Greece, which is an area characterized by aggravated air quality and is currently in a transition phase because of changes in the energy production strategy to reduce the use of lignite as an energy fuel; and (b) the survey’s timing, characterized by new working conditions implemented during the COVID-19 pandemic period. In-site measurements were performed to identify the indoor air pollutants to which the occupants were exposed, while questionnaires were collected regarding the participants’ perception of the working environment conditions, indoor air quality, and health symptoms. The statistical analysis results showed that the most-reported health symptoms were headache, dry eyes, and sneezing. The acceptance of new working conditions showed a significant correlation with their overall comfort and health perception. Occupants in offices with higher pollutant concentrations, such as NO2, benzene and toluene, were more likely to report health symptoms. The evaluation of the plausible health risks for the occupants of the buildings with carcinogenic and no-cancer models showed that health problems could exist despite low pollutant concentration levels.

Rapid Determination of Selected PFAS in Textiles Entering the Waste Stream.

Due to new European legislation, products entering the waste stream containing some perfluoro alkyl substances (PFAS) are subject to "low persistent organic pollutant concentration limits". Concentrations of restricted PFAS must be below this limit for them to be legally recycled or disposed of. A rapid extraction and clean-up method was developed for the determination of 21 PFAS in various polymers used in soft furnishings and upholstery. The optimised method used vortexing and ultrasonication in methanol (0.1% NH4OH), followed by a dilution and syringe filter clean-up step. PFAS were subsequently determined via UPLC-TripleTOF/MS. Good recoveries (80-120%) of target analytes were obtained with tall and narrow chromatogram peaks. The method was validated using control matrix samples spiked with target analytes. Repeated measurements of concentrations of target compounds showed good agreement with the spiked concentrations demonstrating good accuracy and precision. The resultant extracts provided low noise levels resulting in low limits of quantification ranging from 0.1 to 0.4 mg/kg. The developed method was applied successfully to real consumer products and it provided various advantages over traditional methods, including a substantially reduced analysis time, consumables and solvent consumption, and a high sample throughput which is critical to comply with implemented and proposed legislation.

Advanced Plasmonic Nanosensors for Monitoring of Environmental Pollutants

Background:Water is polluted day by day with biological and chemical toxins that can pose a serious threat to human health, animals and ecosystems. The regular identification and monitoring of biological and chemical toxins in water resources is the first step of the preventive method. The devices used in traditional detection methods such as adsorption and chromatography combined with mass spectrometry are not easy to transport for analysis and involve laborious preliminary sample preparation steps. However, the developments in nanosensors prepared with nanomaterials provide solutions to these challenges. Nanomaterials such as gold nanoparticles, graphene and quantum dots are often preferred for the surface preparation of plasmonic nanosensors for the selective, sensitive and label-free detection of very low concentrations of pollutants in water.Methods:There are different plasmonic nanosensors such as electrochemical, colorimetry and optical sensors prepared using different nanomaterials for the determination of environmental pollutants. These different detection nanosensors also have many advantages and disadvantages. In this review, the use of different nanomaterials in different types of plasmonic nanosensors for the determination of environmental pollutants, their modification and their effects on performance in terms of signal enhancement will also be discussed.Results::When the studies in the literature are examined, although many articles have been published on the detection of pollutants in water, the number of publications specific to nanomaterial-based plasmonic nanosensors for detection is quite limited. In this review, we focused on the use of different nanomaterials in the preparation of nanosensor surfaces for the detection of environmental pollutants, and the preparation, optimization, experimental analysis and application areas of different plasmonic nanosensors made in the literature for detection methodsConclusion::Recent developments in plasmonic nanosensors, nanomaterials such as gold nanoparticles, graphene and quantum dots provide ultra-sensitive detection at the molecular level, leading to extraordinary developments. Nanomaterials have important plasmonic properties and are preferred for the selective, sensitive and label-free detection of very low water pollutant concentrations. In studies conducted in the literature, it has been observed that environmental pollutants such as toxin, bacteria, heavy metal ions, pesticides, especially in water, are determined and analyzed. In these review, it was observed that the sensitive and selective properties of nanomaterial-based nanosensors yielded results with low detection limits. The current review includes developments and application-oriented progress of nanomaterial-based plasmonic nanosensors, especially for the detection and quantification of various pollutants and environmental pollutants in water.

Single atom catalyst-mediated generation of reactive species in water treatment.

Water is one of the most essential components in the sustainable development goals (SDGs) of the United Nations. With worsening global water scarcity, especially in some developing countries, water reuse is gaining increasing acceptance. A key challenge in water treatment by conventional treatment processes is the difficulty of treating low concentrations of pollutants (micromolar to nanomolar) in the presence of much higher levels of inorganic ions and natural organic matter (NOM) in water (or real water matrices). Advanced oxidation processes (AOPs) have emerged as an attractive treatment technology that generates reactive species with high redox potentials (E0) (e.g., hydroxyl radical (HO˙), singlet oxygen (1O2), sulfate radical (SO4˙-), and high-valent metals like iron(IV) (Fe(IV)), copper(III) (Cu(III)), and cobalt(IV) (Co(IV))). The use of single atom catalysts (SACs) in AOPs and water treatment technologies has appeared only recently. This review introduces the application of SACs in the activation of hydrogen peroxide and persulfate to produce reactive species in treatment processes. A significant part of the review is devoted to the mechanistic aspects of traditional AOPs and their comparison with those triggered by SACs. The radical species, SO4˙- and HO˙, which are produced in both traditional and SACs-activated AOPs, have higher redox potentials than non-radical species, 1O2 and high-valent metal species. However, SO4˙- and HO˙ radicals are non-selective and easily affected by components of water while non-radicals resist the impact of such constituents in water. Significantly, SACs with varying coordination environments and structures can be tuned to exclusively generate non-radical species to treat water with a complex matrix. Almost no influence of chloride, carbonate, phosphate, and NOM was observed on the performance of SACs in treating pollutants in water when nonradical species dominate. Therefore, the appropriately designed SACs represent game-changers in purifying water vs. AOPs with high efficiency and minimal interference from constituents of polluted water to meet the goals of water sustainability.

Outdoor air pollution and respiratory health.

The need to address the impact of air pollution on health is reinforced by recent scientific evidence and the 2021 WHO Air Quality Guidelines (AQG). Air pollution is an avoidable risk factor causing a high burden for society with elevated deaths, health disorders, disabilities and huge socio-economic costs, especially in low- and middle-income countries. We have evaluated recent evidence from international reports, systematic reviews and official websites of international agencies. Growing evidence shows a causal relationship between air pollution exposure and acute lower respiratory infections, chronic obstructive pulmonary disease, asthma and lung cancer. Exposure to air pollution in both the short- and long-term has a serious impact on respiratory health. Harmful effects occur even at very low pollutant concentration levels, and there are no detectable thresholds below which exposure may be considered safe. The adverse respiratory health effects of air pollutants, even at low levels, are confirmed by recent epidemiological studies. Scientific respiratory societies and patient associations, along with other stakeholders in the health sector, should increase their engagement and advocacy to raise awareness of clean air policies and the latest WHO AQG.

Preparation of combined hydrogel solution that is suitable to control the emission of odor pollutants from brownfield site and its control effects.

Odor pollution caused by brownfield site has attracted increasing attention. However, to date, fewer suitable materials can be used to control the emission of odor pollutant from brownfield site during remediation. This study prepared a kind of combined hydrogel solution based on sodium alginate and carboxymethyl cellulose sodium (CHS-SC) and tested the possibility of its membrane in controlling the emission of three odor pollutants (trichloroethylene, dimethyl disulfide, and p-xylene) from polluted soil. Our results showed that CHS-SC membrane could effectively control the emission of three odor pollutants from polluted soil. Comparatively, CHS-SC membrane had higher control rates for three odor pollutants at high ambient temperature (32°C), short storage time of CHS-SC (5days, 25°C), and low odor pollutant concentration (2ml/kg soil) than at low ambient temperature (2°C), long storage time of CHS-SC (10 d, 25°C), and high odor pollutant concentration (4ml/kg soil), respectively. CHS-SC membrane was degraded by 79.23% after 150days in soil and slightly changed soil bacterial community, indicating that it had good biodegradability and environmental friendliness. In addition, CHS-SC cost was the lowest among the products with similar function. This study shows that CHS-SC is effective in short-timely controlling the emission of odor pollutants from brownfield site.

Magnetic Fe/Fe3C@C Nanoadsorbents for Efficient Cr (VI) Removal

Magnetic carbon nanocomposites (α-Fe/Fe3C@C) synthesized employing fructose and Fe3O4 magnetite nanoparticles as the carbon and iron precursors, respectively, are analyzed and applied for the removal of Cr (VI). Initial citric acid-coated magnetite nanoparticles, obtained through the co-precipitation method, were mixed with fructose (weight ratio 1:2) and thermally treated at different annealing temperatures (Tann = 400, 600, 800, and 1000 °C). The thermal decomposition of the carbon matrix and the Fe3O4 reduction was followed by thermogravimetry (TGA) and Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, Raman spectroscopy, SQUID magnetometry, and N2 adsorption-desorption isotherms. A high annealing temperature (Tann = 800 °C) leads to optimum magnetic adsorbents (high magnetization enabling the magnetic separation of the adsorbent from the aqueous media and large specific surface area to enhance the pollutant adsorption process). Cr (VI) adsorption tests, performed under weak acid environments (pH = 6) and low pollutant concentrations (1 mg/L), confirm the Cr removal ability and reusability after consecutive adsorption cycles. Physical adsorption (pseudo-first-order kinetics model) and multilayer adsorption (Freundlich isotherm model) characterize the Cr (VI) absorption phenomena and support the enhanced adsorption capability of the synthesized nanostructures.

Associations between long-term air pollution exposure and the incidence of cardiovascular diseases among American older adults

Background & aimNumerous studies have linked air pollution with cardiovascular diseases. Fewer studies examined the associations at low concentration levels or assessed potential modifiers. Some investigations only examined hospitalizations, which can miss incident cases. This study aims to address these gaps through a nationwide cohort study of Medicare enrollees. MethodsOur study cohort comprise all Medicare enrollees (≥65 years old) continuously enrolled in the fee-for-service program and both Medicare part A and B across the contiguous U.S. from 2000 to 2016. We examined the associations of population-weighted ZIP code-level annual average PM2.5, NO2, and warm-season O3 (May-October), with the first diagnoses of atrial fibrillation (AF), congestive heart failure (CHF), and stroke. We fit multi-pollutant Cox proportional hazards models adjusted for individual demographic characteristics and area-level covariates. We further examined these associations at low pollutant concentration levels and the potential effect modifications by race/ethnicity and comorbidities (diabetes, hypertension, hyperlipidemia). ResultsElevated PM2.5 and NO2 levels were associated with increased incidence of AF, CHF, and stroke. For each 1 μg/m3 increase in annual PM2.5, hazard ratios (HRs) were 1.0059 (95%CI: 1.0054-1.0064), 1.0260 (95%CI: 1.0256-1.0264), and 1.0279 (95%CI: 1.0274-1.0284), respectively. For each1 ppb increase in annual NO2, HRs are 1.0057 (95%CI: 1.0056-1.0059), 1.0112 (95%CI: 1.0110-1.0113), and 1.0095 (95%CI: 1.0093-1.0096), respectively. For warm-season O3, each 1 ppb increase was associated with increased incidence of CHF (HR=1.0035, 95%CI: 1.0033–1.0037) and stroke (HR=1.0026, 95%CI: 1.0023–1.0028). Larger magnitudes of HRs were observed when restricted to pollutants levels lower than NAAQS standards. Generally higher risks were observed for Black people and diabetics. ConclusionsLong-term exposure to PM2.5, NO2, and warm-season O3 were associated with increased incidence of cardiovascular diseases, even at low pollutant concentration levels. Black people and people with diabetes were found to be vulnerable populations.

Microbial Biosensors for Wastewater Monitoring: Mini-Review

Research on the use of microbial biosensors for monitoring wastewater contaminants is a topic that covers few publications compared to their applicability in other fields, such as biomedical research. For this reason, a systematic analysis of the topic was carried out, for which research-type articles were reviewed during the period 2012 to September 2022. For this, different search platforms were used, including PubMed, ScienceDirect, Springer Link, and Scopus, and through the use of search equations a relevant bibliography was located. After that, the research articles were selected based on exclusion criteria. As a result, it was found that, of the 126 articles, only 16 articles were strictly related to the topic, since there was a duplication of articles among the different databases. It was possible to demonstrate the usefulness of microorganisms as components of biosensors to monitor BOD, heavy metals, and inorganic contaminants in wastewater that also had a high sensitivity. Additionally, recombinant DNA techniques were shown to improve the performance of this type of biosensor and can finally be coupled to other emerging technologies, such as microbial fuel cells (MFCs). In conclusion, it was established that microbial biosensors have high acceptability and monitoring characteristics that make them a useful tool to detect low concentrations of pollutants in wastewater that can also provide results in real-time, thus generating forms of ecological safety and social responsibility in companies where wastewater is generated.

Ultrasound/Chlorine: A Novel Synergistic Sono-Hybrid Process for Allura Red AC Degradation

Herein, we present an original report on chlorine activation by ultrasound (US: 600 kHz, 120 W) for intensifying the sonochemical treatment of hazardous organic materials. The coupling of US/chlorine produced synergy via the involvement of reactive chlorine species (RCSs: Cl•, ClO• and Cl2•−), resulting from the sono-activation of chlorine. The degradation of Allura Red AC (ARAC) textile dye, as a contaminant model, was drastically improved by the US/chlorine process as compared to the separated techniques. A synergy index of 1.74 was obtained by the US/chlorine process for the degradation of ARAC (C0 = 5 mg·L−1) at pH 5.5 and [chlorine]0 = 250 mM. The synergistic index increased by up to 2.2 when chlorine concentration was 300 µM. Additionally, the synergetic effect was only obtained at pH 4–6, where HOCl is the sole chlorine species. Additionally, the effect of combining US and chlorine for ARAC degradation was additive for the argon atmosphere, synergistic for air and negative for N2. An air atmosphere could provide the best synergy as it generates a relatively moderate concentration of reactive species as compared to argon, which marginalizes radical–radical reactions compared to radical–organic ones. Finally, the US/chlorine process was more synergistic for low pollutant concentrations (C0 ≤ 10 mg·L−1); the coupling effect was additive for moderate concentrations (C0~20–30 mg·L−1) and negative for higher C0 (>30 mg·L−1). Consequently, the US/chlorine process was efficiently operable under typical water treatment conditions, although complete by-product analysis and toxicity assessment may still be necessary to establish process viability.

Benefits of future clean air policies in Europe: Proposed analyses of the mortality impacts of PM2.5 and NO2.

Benefits of future clean air policies in Europe: Proposed analyses of the mortality impacts of PM2.5 and NO2.

Long-term exposure to low air pollutant concentrations and hospitalisation for respiratory diseases in older men: A prospective cohort study in Perth, Australia

BackgroundAcute exposure to ambient air pollution even at low concentrations has been associated with increased hospitalisation for respiratory diseases but the effects of long-term exposure are less certain. In this study, we investigated the associations between long-term exposures to PM2.5, PM2.5 absorbance and NO2 and hospitalisation for asthma, chronic obstructive pulmonary disease and pneumonia in a cohort of older men living in Perth, Western Australia, a city where the levels of air pollutants are well below the world standards. Materials and methodsThe study population of 11,156 men with no prior hospitalisation for respiratory disease was drawn from the Health in Men Study (HIMS) cohort of men aged >65 years living in Perth, Western Australia between 1996-1999. PM2.5, PM2.5 absorbance (PM2.5a) and NO2 were measured across the Perth metropolitan area over three seasons in 2012. Land use regression (LUR) models were used to estimate annual concentrations of PM2.5, PM2.5 absorbance and NO2 at the residential address of each participant from inception (1996) to 2015. Hospitalisation for respiratory disease between inception and 2015 was ascertained using the Western Australian Data Linkage System. The association between exposure to air pollution with hospitalisation for respiratory disease was examined using Cox regression analysis. ResultsNo statistically significant associations were observed in the fully adjusted models. However, positive associations were observed with first hospitalisation for pneumonia (HR 1.08, 95% CI: 1.01–1.16) when adjusted for age, year of enrolment, smoking status, education, BMI and physical activity. ConclusionsIn this longitudinal study of older men we found no evidence of associations between increased long-term exposure to low-level air pollution with increased risk of hospitalisation for respiratory diseases in Perth, Australia. More studies on respiratory morbidity associated with exposure to low levels of air pollution are needed for more comprehensive understanding of the overall risk.

Ambient air pollution and risk of incident dementia in older men living in a region with relatively low concentrations of pollutants: The Health in Men Study

BackgroundIn areas with moderate to severe air pollution, pollutant concentrations are associated with dementia risk. It is unclear whether the same relationship is present in regions with lower ambient air pollution. ObjectiveTo determine whether exposure to air pollution is associated with risk of incident dementia in general, and Alzheimer's disease and vascular dementia in particular, in older men living in a relatively low ambient air pollution region. MethodsThe cohort comprised 11,243 men residing in Perth, Australia. Participants were aged ≥65 years and free of a dementia diagnosis at time of recruitment in 1996–1999. Incident dementia was identified from recruitment to 2018 via ICD diagnosis codes and subsequent study waves. Concentrations for three air pollutants, nitrogen dioxide (NO2), fine particulate matter less than 2.5 μm in diameter (PM2.5), and black carbon (BC) were estimated at participants’ home addresses using land-use regression models. We used Cox proportional hazards regression models adjusting for smoking status, physical activity, BMI, education, and socio-economic status. ResultsOf 3053 (27.2%) incident cases of dementia, 1670 (54.7%) and 355 (11.6%) had documented Alzheimer's disease and vascular dementia. The average concentration of NO2 was 13.5 (SD 4.4) μg/m3, of PM2.5 was 4.54 (SD 1.6) μg/m3 and of BC was 0.97 (SD 0.29) ×10−5 m−1. None of the air pollutants were associated with incident dementia or Alzheimer's disease. In the unadjusted model, increased exposure to PM2.5 was associated with an increased risk of vascular dementia (for a 5 μg/m3 increase: HR 1.62, 95% CI 1.13, 2.31). However, this association was attenuated following adjustment for confounders (HR 1.39, 95% CI 0.93, 2.08). NO2 and BC were not associated with vascular dementia incidence. DiscussionExposure to air pollution is not associated with increased risk of incident dementia in older men living in a region with relatively low ambient air pollution.

Analyzing greenhouse gas emissions from municipal wastewater treatment plants using pollutants parameter normalizing method：a case study of Beijing

Wastewater treatment plants (WWTPs) contribute increasing amounts of greenhouse gases (GHGs), due to rapid development and increasingly stringent wastewater discharge limits in China. In this study, GHG emissions from 38 WWTPs in Beijing were estimated using the pollutants parameter normalizing method (PPNM) and the effects of various factors were analyzed. The result showed that, the total GHG emissions of Beijing WWTPs in 2017 were 1 045 661.5 t CO2-eq (tons of CO2-equivalent), the direct and indirect emissions were 186 366.0 and 859 295.5 t CO2-eq, respectively. The average emission intensity was 0.603 kg CO2-eq/m3. Direct and indirect GHG emissions were influenced by various factors, such as treatment process, influent parameters and treatment scale. The anaerobic-anoxic-oxic (AAO) process demonstrated low emission intensities (0.092 kg CO2/m3), while biofilm processes (MBBR) obtained relatively high emission intensities (0.277 kg CO2/m3). Direct GHG emission has a positive correlation with the amount of pollutant removed and low influent pollutant concentrations (chemical oxygen demand [COD]<300 mg/L and total nitrogen [TN] <20 mg/L) can lead to high indirect GHG emission intensities. The low power utilization efficiency of small-scale WWTPs (<1 × 107 t/a; 6.60 kWh/kg COD; 30.54 kWh/kg TN) contributed to additional GHG emissions. Compared with the GHG emissions in Shanghai in 2016, higher influent pollutant concentrations and stricter discharge limits contributed to higher GHG emission intensity in Beijing for both direct (0.108 kg CO2/m3) and indirect (0.496 kg CO2/m3) emissions. The comparison results between cities indicated that the PPNM method achieved a more accurate account of GHG emissions, and the analysis results provided support for carbon emission reduction.

Effects of Urban Landscapes on Pollutant Concentrations in Chengdu Plain Urban Agglomeration

Frequent air pollution due to urbanization poses a severe threat to urban environments. In this study, the effects of urban landscapes on pollutant concentrations at different spatial and temporal scales are examined using “3S” technology, based on land-use (LU) classification maps for two time phases (2015 and 2018) in conjunction with monitoring data for air pollutants of the same periods. The results showed that: (1) A very high overall LU ratio was found for Chengdu Plain urban agglomeration (CPUA), with only 0.3% of the land being unused. Farmlands (43%), forests (36.45%), and grasslands (14.17%) were identified as the main landscape types. A decrease in the proportions of the total area occupied by farmlands and grasslands was 0.44% and 0.72%, respectively, and 0.10%, 0.04%, and 0.97% increased in the proportions of the total area occupied by forests, water bodies, and developed lands, respectively, were found from 2015 to 2018. (2) NO2, PM2.5, and PM10 were mainly distributed in the central and eastern parts of the study area, while SO2 was mainly distributed in the southwest. In 2018, compared with 2015, the maximum concentration of NO2 decreased from 60.36 μg/m3 to 49.75 μg/m3, and the distribution range of high concentration NO2 was reduced and concentrated in Chengdu; the concentrations of PM10 and PM2.5 decreased significantly, and the maximum concentration decreased by 20.53% and 23.93%, respectively, but the concentration of pollution in the northeast increased significantly. The scope of SO2 pollution had shifted from the south to the southwest, and the pollution level had decreased from south to north. (3) The effects of various landscape types on pollutant concentrations were complex. At a patch-type level, increasing the area proportions of “pollution-reducing” landscape types could reduce pollutant concentrations. Specifically, increasing the area, largest patch index, and patch cohesion of forests and grasslands, as well as reducing the area, largest patch index, and patch cohesion of farmlands and developed lands, could effectively lower pollutant concentrations. From a landscape pattern perspective, high shape regularity and low diversity of landscape patches resulted in high concentrations of NO2, PM10, and PM2.5. In contrast, high levels of dominance and aggregation of landscapes lead to low concentrations of SO2.

POP-BFRs in consumer products: Evolution of the efficacy of XRF screening for legislative compliance over a 5-year interval and future trends

In 2015–16, a study of approximately 500 waste plastic articles showed that portable X-ray fluorescence (XRF) was up to 95 % effective in screening for compliance with low persistent organic pollutant (POP) concentration limits (LPCLs) on brominated flame retardants (BFRs) in waste. The present study conducted in 2019–20 mirrors that conducted five years prior on a similar number and range of articles, testing the hypothesis that increased use of alternative BFRs as replacements for POP-BFRs will reduce the effectiveness of XRF as a tool for monitoring compliance with LPCLs. In comparing the results, the overall screening efficacy for LPCL compliance reduced from ~95 % to ~88 %, due in part to decreased prevalence of POP-BFRs and potentially increased presence of alternative flame retardants, particularly in goods with shorter lifecycles such as electronics. We additionally examined the impacts of a number of modifications to the XRF measurement protocol on its efficacy, including: using elemental Sb as a qualifier in detecting POP-BFRs in hard plastics; reduced XRF analysis time; and the elimination of background interference using a test stand. The rate at which hard plastics from electronic waste may be analysed by XRF can be substantially improved by reducing analysis time to 5 s, with minimal increase in false exceedances of the LPCL. Monitoring Sb does not appear an effective qualifier for the presence of POP-BFRs, as Sb seems to be used with a range of BFRs. Use of the test stand, while reducing interference, appeared to reduce accuracy when screening low density and thin samples. Despite a seeming increased use of alternative BFRs, screening of waste for compliance with LPCLs using rapid and low-cost screening methods such as portable XRF is still necessary as methods such as GC–MS cannot be scaled up to match the quantities of waste requiring screening.

Simultaneous nitritation, denitritation and phosphorus removal in an algal-bacterial consortium system treating low-strength mariculture wastewater

Mariculture wastewater is characterized by high salinity and low concentration of pollutants, which poses a great challenge to the conventional wastewater treatment processes. In this study, an algal-bacterial consortium process for simultaneous organic carbon, nitrogen and phosphorus removal from such wastewater was investigated in a red-blue (4:1) LED photo-sequencing batch reactor (PSBR). Simultaneous bacterial ammonium oxidation (70 %) and algal ammonium assimilation (30 %) was obtained in the photo phase. In the dark phase, a weak ammonium assimilation was also observed. In the PSBR with an influent COD/N of 5:1, the nitrogen removal pathway was identified to be simultaneous nitritation and denitritation probably due to low-rate oxygenation of algae at a light luminance of 500 lx. In addition, the average COD and phosphorus removal efficiencies reached 82.4 % and 68.2 % with a removal activity of 0.63 mg PO43−-P/(L·d). High-throughput sequencing results showed that Nitrosomonus and Nitrospina were the dominant nitrifying genera using oxygen released by Cyanobacteria and Bacillariophyta. Therefore, it is feasible to efficiently remove nitrogen and phosphorus from mariculture wastewater by the algal-bacterial consortium, which opens a new window for the treatment of high-salinity and low-strength wastewater.

Morphological and behavioral alterations in zebrafish larvae after exposure to contaminated river sediments collected in different weather conditions

Wastewater treatment plants (WWTPs) are the primary source of micropollutants in aquatic ecosystems. Many micropollutants tend to bind to sediments and persist until remobilizion by bioturbation or flood events. Advanced effluent treatment by ozonation has been proven to eliminate most micropollutants.The present study characterizes sediments' toxic potential regarding zebrafish embryo development, which highly complex nervous system is vulnerable to exposure to neurotoxic substances. Furthermore, behavioral changes can be induced even at low pollutant concentrations and do not cause acute toxicity.The study area includes stretches of the main waterbody, the Wurm River (sampling sites W1-W5), and its tributary the Haarbach River (sampling sites H1, and H2) in North-Rhine Westphalia, Germany. Both waterbodies serve as recipients of WWTPs' effluents. The effluent entering the Haarbach River is conventionally treated, while the Wurm River receives ozonated effluent from the Aachen-Soers WWTP. Seven sampling sites up- and downstream of the WWTPs were investigated in June of two subsequent years. The first sampling campaign in 2017 was characterized by prolonged dry weather. The second sampling campaign in 2018 occurred after prolonged rain events and the release of the rainwater overflow basin.Direct exposure of zebrafish embryos to native sediments using the sediment contact test represented an ecologically realistic scenario and showed no acute sublethal effects. Exposure of the zebrafish embryo to freeze-dried sediments representing the ecotoxicological status of sediments during flood events unfolded acute sublethal toxicity. Behavioral studies with zebrafish larvae were an essential part of environmental neurotoxicity testing. Zebrafish larvae exposed to sediments' concentrations causing no acute effects led to behavioral changes signalizing neurotoxic substances in sediments. Polyaromatic hydrocarbons, polychlorinated biphenyls, and nitroaromatic compounds were identified as potential toxicity drivers, whereby the rainwater overflow basin served as a possible source of pollution. Mixture toxicity, effect-directed analysis, and further sediment monitoring are needed.

Improved Electron Efficiency of Zero-Valent Iron towards Cr(VI) Reduction after Sequestering in Al2O3 Microspheres.

Zero-valent iron (ZVI) is widely used for groundwater remediation, but suffers from high electron consumption because of its free contact with non-target substrates such as O2. Here, ZVI-ALOX particles were prepared via in situ NaBH4 aqueous-phase reduction of ferrous ions (Fe2+) preabsorbed into Al2O3 microspheres. The electron efficiency (EE) and long-term performance of the material were improved by sequestering ZVI in the interspace of the Al2O3 microspheres (ZVI-ALOX). During long-term (350 days) continuous flow, Cr(VI) was removed to below the detection limit for over 23 days. Based on the high reactivity of ZVI towards Cr(VI), the EE of ZVI-ALOX was evaluated by measuring its Cr(VI) removal efficiency at neutral pH and comparing it with that of ZVI. The results showed that the EE of ZVI-ALOX during long-term continuous flow could reach 39.1%, which was much higher than that of ZVI (8.68%). The long-term continuous flow results also demonstrated that treatment of the influent solution achieved higher EE values than in the batch mode, where the presence of dissolved oxygen reduced EE values. At lower pollutant concentrations, the sequestering of ZVI was beneficial to its performance and long-term utility. In addition, measurement of the acute toxicity of treated column effluent using the indicator organism Photobacterium phosphoreum T3 showed that ZVI-ALOX could reduce the toxicity of 5 mg/L Cr(VI) solution by ~70% in 350 d. The results from this study provide a basis for the development of permeable reactive barriers for groundwater remediation based on sequestered ZVI.