Urban Sites Research Articles

A Case Report on Product Rotation to Manage Severe Lysinibacillus sphaericus Resistance in Culex pipiens from Salt Lake City, Utah.

The Salt Lake City Mosquito Abatement District (SLCMAD) detected a 20,000-fold resistance to Lysinibacillus sphaericus (Lsph) in Culex pipiens occurring in catch basins of Salt Lake City during 2016. In response, SLCMAD suspended use of Lsph and rotated use of spinosyn and s-methoprene products for the next three years. At the end of the third year, Lsph was evaluated again and efficacy similar to susceptible colony strains. During the second year of Lsph use, technicians observed lack of control of larvae at some urban sites. Bioassays performed during 2021 showed recurrence of some resistance to Lsph to varying degrees across SLCMAD urban areas. The rapidity with which resistant phenotypes reemerged clarifies that SLCMAD cannot in the near future rely on repeated use of Lsph, even after suspending use for three years and using within-season product rotations. Prior reports in other research groups have found long-term selection to Lsph, as is the case at SLCMAD, to not regress in spite of halting use of the products. However, our findings offer some optimism that regression may be relatively quick. More operational review is needed, and future work should characterize resistance alleles in field populations. Collectively, there is a lack of concrete data supporting the prevailing assumptions from adjacent industries that were adopted into mosquito abatement. We provide this short note as additional guidance for mosquito and vector control districts weighing options to remediate Lsph resistance.

Small is beautiful? Making sense of ‘shrinking’ homes

Current land pressures in the world cities of the global North are encouraging a move towards denser urban living and the development of smaller homes than has been the case for many decades. While this appears environmentally beneficial when compared with the alternative of suburban sprawl, it comes at a cost: the number of extremely small homes appears to be increasing particularly rapidly, with less communal and public space available to those living in compact homes which offer little room for socialising, storing possessions or working from home. Drawing specifically on the experience of England and Wales, with a focus on the overheated property market in London, this commentary sets out an international agenda for the study of small homes, noting the growing evidence of the negative impact of dense urban living on mental and physical health, home-working and familial and intimate relations, as well as its failure to solve the crisis of affordability. The article suggests that rather than being a reasoned response to the housing and environmental crises, the phenomenon of ‘shrinking homes’ indicates the growing role of finance in the development of cities, suggestive of the way that developers are extracting maximum value from restricted urban sites in an era of planning deregulation. In conclusion, the commentary argues that urban scholarship needs to compile more evidence of space inequality in cities, pushing for policies designed to enforce minimal space standards while reducing the ability of the wealthy to construct very large homes.

Nesting ecology and confirmed breeding of the invasive pond slider Trachemys scripta in an urban environment, Romania

The pond slider (Trachemys scripta) is a major invasive species in freshwater habitats across the world. For decades, the main cause of individuals’ occurrences in the wild was the illegal release of pet animals. Recently, as an important component of their management, there has been an increasing focus on their ability to successfully reproduce in the invaded regions. In Romania, the species is reported as widespread in urban wetland environments within major cities, but information about its nesting and potential breeding remains scarce or anecdotal. We surveyed a large population of pond sliders in an artificial urban wetland site in Constanţa, SE Romania, and described their nesting ecology and reproductive output. Although eggs from several nests failed to hatch or were predated, potentially limiting their reproductive success, sliders were found to breed successfully at this site, with 18.6% viable hatchlings recorded. Our study could serve as a baseline for additional targeted surveys and to inform decision-making for successfully managing this invasive species. Although the importation, trading, and breeding of this species are prohibited by EU legislation, active and effective management is now required to address the successful reproduction and further potential spread of T. scripta.

Road salt applications mobilize trace elements from roadside soil to shallow groundwater

In regions where deicers are applied to roadways, micronutrients and toxic trace elements may be mobilized from soil material into soil porewater. These elements may subsequently migrate with soil porewater to surface waters and groundwaters, potentially leaching the soil of micronutrients or introducing toxins to water resources. Our study thus aims to quantify the timing and extent of trace element releases from soil material to soil porewater and groundwater in response to deicing events. We sampled soil porewater near a road at a rural site for trace elements and compared the results to salt applications and soil porewater Na and Cl levels. We also assessed trace element, Na, and Cl concentrations in a karst spring at the rural site and a karst spring at an urban site to evaluate the role of land use in conveying these contaminants to groundwater. We found that certain trace elements (e.g., As, Ba, Fe, Sr) peaked concomitantly with Na and Cl in soil porewater at the rural site after road deicing events, suggesting their release due to excess salt inputs to the soil. We did not observe increases in trace element concentrations at the rural karst spring following individual road salt applications, likely due to low deicer inputs and trace element levels across its recharge basin. However, at the urban site, we observed that other assemblages of trace elements (e.g., As, Cu, Li) in the karst spring peaked with deicing-related Na and Cl pulses. We also found positive and significant correlations between salt applications to the recharge basin and exports of some trace elements (e.g., As, Cu, Li, Se) at the urban karst spring, indicating deicing events triggered trace element releases to groundwater. Overall, we detected road salt-driven trace element release from soil material to soil porewater and groundwater that was exacerbated by urbanization.

Correction: Sustainable reuse potential of landfill mining waste retrieved from urban mining sites in South India

Correction: Sustainable reuse potential of landfill mining waste retrieved from urban mining sites in South India

Measurement report: Optical characterization, seasonality, and sources of brown carbon in fine aerosols from Tianjin, North China: year-round observations

Abstract. To investigate the optical characteristics and sources of brown carbon (BrC) in North China, where the atmospheric aerosol loadings are high and have severe impacts on Earth's climate system, we collected fine aerosols (PM2.5) at an urban site in Tianjin over a 1-year period. We measured the ultraviolet (UV) light absorption and excitation emission matrix (EEM) fluorescence of the water-soluble BrC (WSBrC) and the water-insoluble but methanol-soluble BrC (WI-MSBrC) in the PM2.5 using a three-dimensional fluorescence spectrometer. The average light absorption efficiency of both WSBrC (Abs365, WSBrC) and WI-MSBrC (Abs365, WI-MSBrC) at 365 nm was found to be highest in winter (10.4 ± 6.76 and 10.0 ± 5.13 Mm−1, respectively) and distinct from season to season. The averages of the fluorescence index (FI) and the biological index (BIX) of WSBrC were lower in summer than in the other seasons and opposite to that of the humification index (HIX), which implied that the secondary formation and further chemical processing of aerosols were more intensive during the summer period than in the other seasons. However, in winter, the higher HIX together with the higher FI and BIX of WI-MSBrC suggested that the BrC loading was mainly influenced by primary emissions from biomass burning and coal combustion. Based on the EEM, the types of fluorophores in WSBrC were divided into humic-like substances (HULIS), including low-oxygenated and high-oxygenated species and protein-like compounds (PLOM), though mostly PLOM in the WI-MSBrC. The direct radiation absorption by both WSBrC and WI-MSBrC in the range of 300–400 nm accounted for ∼ 40 % of that (SFEAbs, 4.97 ± 2.71 and 7.58 ± 5.75 W g−1, respectively) in the range 300–700 nm.

Evaluation of residual sodium carbonate (RSC) and sodium adsorption ratio (SAR) in fresh water and laundry grey water for irrigation usage

AbstractThe current study was carried out to assess the suitability of laundry grey water (LGW) for reuse in irrigation so that it can help in the reduction of freshwater stress in irrigation sector. To address this objective, concentration of sodium (Na+), calcium (Ca2+), magnesium (Mg2+), carbonate (CO32−), bicarbonate (HCO3−), and phosphate (PO43−) were tested in fresh water (FW) collected before laundry washing and LGW generated after laundry washing from different households. The suitability of LGW for irrigation purpose was determined by using water quality indices such as Sodium adsorption ratio (SAR) and Residual Sodium Carbonate (RSC). The SAR values of FW at the rural and urban area sites varied from 0.84 to 1.10 and 0.82 to 4.30 respectively and remained in the excellent category for irrigation purpose. The SAR values of LGW at the rural and urban sites varied from 10.06 to 13.01 and 6.26 to 9.68, respectively. In contrast to the SAR values of the LGW at rural site, which remained under good quality category, SAR values remained under excellent category for irrigation purpose at urban sites. RSC values of FW and LGW were below 3.97 showing low or medium hazards associated with it for irrigation.

Oxidative potential of particulate matter and its association to respiratory health endpoints in high-altitude cities in Bolivia

Exposure to particulate matter (PM) pollution is a significant health risk, driving the search for innovative metrics that more accurately reflect the potential harm to human health. Among these, oxidative potential (OP) has emerged as a promising health-based metric, yet its application and relevance across different environments remain to be further explored. This study, set in two high-altitude Bolivian cities, aims to identify the most significant sources of PM-induced oxidation in the lungs and assess the utility of OP in assessing PM health impacts. Utilizing two distinct assays, OPDTT and OPDCFH, we measured the OP of PM samples, while also examining the associations between PM mass, OP, and black carbon (BC) concentrations with hospital visits for acute respiratory infections (ARI) and pneumonia over a range of exposure lags (0–2 weeks) using a Poisson regression model adjusted for meteorological conditions. The analysis also leveraged Positive Matrix Factorization (PMF) to link these health outcomes to specific PM sources, building on a prior source apportionment study utilizing the same dataset. Our findings highlight anthropogenic combustion, particularly from traffic and biomass burning, as the primary contributors to OP in these urban sites. Significant correlations were observed between both OPDTT and PM2.5 concentration exposure and ARI hospital visits, alongside a notable association with pneumonia cases and OPDTT levels. Furthermore, PMF analysis demonstrated a clear link between traffic-related pollution and increased hospital admissions for respiratory issues, affirming the health impact of these sources. These results underscore the potential of OPDTT as a valuable metric for assessing the health risks associated with acute PM exposure, showcasing its broader application in environmental health studies.

Impact of temperature and season on ant foraging activity of two invasive species in a Mediterranean urban area

Abstract Invasive species often have harmful effects on human activities and biodiversity. The Tapinoma nigerrimum complex includes three species that exhibit invasive traits and the ability to form supercolonies, including Tapinoma magnum and Tapinoma darioi. While these species are native to the Mediterranean basin, they have recently been reported as invasive in more northern regions of Europe. However, T. magnum and T. darioi show different invasion patterns in Europe, suggesting differences in thermal preferences between these species. We aimed to determine whether there was any difference in activity pattern depending on temperature or season between the two Tapinoma species and between Tapinoma and co‐occurring native Mediterranean ants. We measured ambient temperature and ant foraging activity around the nest entrances of T. darioi and T. magnum in urbanised sites around Montpellier, southern France, over almost 1 year. We did not detect differences in activity between the two species according to temperature, but T. magnum was more active than T. darioi in winter. Compared to the co‐occurring native species, the two Tapinoma species were more active at low temperatures and earlier in the year. These results suggest that the difference in invasion success between T. magnum and T. darioi may not be explained by temperature preference. The difference in activity between native Mediterranean species and invasive Tapinoma suggests a coexistence through niche partitioning. In addition, our results suggest that control measures against invasive Tapinoma species would be more effective if applied at the end of winter.

How to restore ecological impacts from wind energy? An assessment of Zhongying Wind Farm through MSPA-MCR model and circuit theory

The wind energy industry is developing rapidly in China with a maximum capacity worldwide. Meanwhile, the stability of the ecological network is challenged by extensive renewable energy expansion. There are still research deficiencies in wind farm ecological impacts at project scale from an ecological restoration perspective. It is of great necessity to monitor the ecological impacts with time going and explore ecological restoration strategies for wind power development. The research case of Zhongying Wind Farm is selected based on investigation and interviews regarding its ecological impact in the prior study. It employs a comparative methodology by comparing the ecological quality before and after the construction of Zhongying Wind Farm. Raw data from Landsat 8, the Digital Elevation Model (DEM), the Normalized Difference Vegetation Index (NDVI), and wind turbine statistics originating from open data platforms are analyzed and visually represented with ArcGIS. This paper establishes an ecological network based on morphological spatial pattern analysis (MSPA) and the Minimum Cumulative Resistance (MCR) model to quantify wind farms’ impacts on ecological corridors. The circuit theory and Pajek software are used to identify and categorize the ecological nodes into weak and obstacle points. The results reveal that ecological impacts on ecological corridors decay with distance, reflecting changes in length, connection strength and cumulative values of corridors. While the impacts on ecological nodes depend on nodes’ attributes: the number of weak points increased by 18.5 %, and obstacle points increased by 350 %, with their locations shifting from the edges of urban construction sites to the edges of wind farm. Differentiated strategies are proposed according to the impact magnitude of each ecological corridor and node: such as dynamic inspection mechanism, construction prohibition for protection; corridor structure and function recovering, stepping stones addition for restoration; buffer belts, warning radar, and monetary schemes for compensation. This research fills the gap of ecological impact assessment under the challenges of wind energy expansion. It helps to balance wind energy development and ecological restoration at the regional level.

A nanogold sensor test for tire wear chemicals based on the plasmon ruler approach

The release of tire wear substances in the environment is raising concerns about potential impacts on aquatic ecosystems. The purpose of this study was to develop a quick and inexpensive screening test for the following tire wear substances: 6-phenylphenyldiamine quinone (6-PPD quinone), hexamethoxymethylmelamine (HMMM), 1–3-diphenylguanidine (1,3-DPG), and melamine. A dual strategy consisting of nanogold (nAu) signal intensity and the plasmonic ruler principle was used based on the spectral shift from the unaggregated free-form nAu from 525 nm to aggregated nAu at higher wavelengths. The shift in resonance corresponded to the relative sizes of the tire wear substances at the surface of nAu: 6-PPD (560 nm), HMMM (590 nm), 1,3-DPG (620 nm), and melamine (660 nm) in a concentration-dependent manner. When present in mixtures, a large indiscriminate band between 550 and 660 nm with a maximum corresponding to the mean intermolecular distance of 0.43 nm from the tested individual substances suggests that all compounds indiscriminately interacted at the surface of nAu. An internal calibration methodology was developed for mixtures and biological extracts from mussels and biofilms and revealed a proportional increase in absorbance at the corresponding resonance line for each test compound. Application of this simple and quick methodology revealed the increased presence of melamine and HMMM compounds in mussels and biofilms collected at urban sites (downstream city, road runoffs), respectively. The data also showed that treated municipal effluent decreased somewhat melamine levels in mussels.Graphical

Carcinogenicity and non-carcinogenicity health risks due to PM2.5 bound trace metals at a sub urban site in Northwest Indo-Gangetic Plain.

This study investigates the PM2.5 bound metals using yearlong measurements at a regionally representative suburban site in the Northwest Indo-Gangetic Plain (NWIGP). The order of the measured annual average concentrations of PM2.5 bound metals is Fe > Zn > Ba > Sn > Pb > Cd > Ni > Mn > Cr > Li. Lithium bound to airborne PM2.5 has been reported for the first time in NWIGP. Ni (72.4 ng m-3) and Cd (36.9 ng m-3) have exceeded the acceptable limits set by NAAQS, India. Estimated the hazard quotient (HQ > 1) of Mn and hazard index (HI > 1) of measured metals exceeded the threshold limits indicating the potential non-carcinogenic health risk due to inhalation exposure of PM2.5 bound trace metals. Further, excessive lifetime cancer risk due to inhalation exposure to Cd, Ni and Cr was estimated and found to exceed the threshold limit set by the USEPA for adults and children.

Elucidating the Effects of COVID-19 Lockdowns in the UK on the O3-NOx-VOC Relationship

The unprecedented reductions in anthropogenic emissions over the COVID-19 lockdowns were utilised to investigate the response of ozone (O3) concentrations to changes in its precursors across various UK sites. Ozone, volatile organic compounds (VOCs) and NOx (NO+NO2) data were obtained for a 3-year period encompassing the pandemic period (January 2019–December 2021), as well as a pre-pandemic year (2017), to better understand the contribution of precursor emissions to O3 fluctuations. Compared with pre-lockdown levels, NO and NO2 declined by up to 63% and 42%, respectively, over the lockdown periods, with the most significant changes in pollutant concentrations recorded across the urban traffic sites. O3 levels correspondingly increased by up to 30%, consistent with decreases in the [NO]/[NO2] ratio for O3 concentration response. Analysis of the response of O3 concentrations to the NOx reductions suggested that urban traffic, suburban background and suburban industrial sites operate under VOC-limited regimes, while urban background, urban industrial and rural background sites are NOx-limited. This was in agreement with the [VOC]/[NOx] ratios determined for the London Marylebone Road (LMR; urban traffic) site and the Chilbolton Observatory (CO; rural background) site, which produced values below and above 8, respectively. Conversely, [VOC]/[NOx] ratios for the London Eltham (LE; suburban background) site indicated NOx-sensitivity, which may suggest the [VOC]/[NOx] ratio for O3 concentration response may have had a slight NOx-sensitive bias. Furthermore, O3 concentration response with [NO]/[NO2] and [VOC]/[NOx] were also investigated to determine their relevance and accuracy in identifying O3-NOx-VOC relationships across UK sites. While the results obtained via utilisation of these metrics would suggest a shift in photochemical regime, it is likely that variation in O3 during this period was primarily driven by shifts in oxidant (OX; NO2 + O3) equilibrium as a result of decreasing NO2, with increased O3 transported from Europe likely having some influence.

Phenomenology of the Composition of PM2.5 at an Urban Site in Northern France

In this work, PM2.5 was sampled at Dunkerque, a medium-sized city located in northern France. The mean concentration of PM2.5 during the sampling period was 12.6 ± 9.5 μg·m−3. Samples were analyzed for elemental and organic carbon (EC/OC), water-soluble organic carbon (WSOC), humic-like substances (HULIS-C), water-soluble inorganic ions, and major and trace elements. The origin and the variations of species concentrations were examined using elemental enrichment factors, bivariate polar plot representations, and diagnostic concentration ratios. Secondary inorganic ions were the most abundant species (36% of PM2.5), followed by OC (12.5% of PM2.5). Secondary organic carbon (SOC) concentrations were estimated to account for 52% of OC. A good correlation between SOC and WSOC indicated that secondary formation processes significantly contribute to the WSOC concentrations. HULIS-C also represents almost 50% of WSOC. The determination of diagnostic ratios revealed the influence of anthropogenic emission sources such as integrated steelworks and fuel oil combustion. The clustering of 72 h air masses backward trajectories data evidenced that higher concentrations of PM2.5, OC, and secondary inorganic aerosols were recorded when air masses came from north-eastern Europe and the French continental sector, showing the considerable impact of long-range transport on the air quality in northern France.

Are young and older children with diarrhea presenting in the same way?

Diarrhoea is a global health problem. More than a quarter of diarrhoeal deaths occur among children less than five years. Different literatures analyzed presentation and outcomes of less than five diarrhoeal children. The world has made remarkable progress in reducing child mortality. So, older children are growing in number. Our aim was to identify clinical differentials and variations of pathogens among younger (less than five) and older (five to nine years) diarrhoeal children. Data were extracted from the diarrhoeal disease surveillance system (DDSS) of Dhaka Hospital (urban site) and Matlab Hospital (rural site) of the International Centre for Diarrhoeal Disease Research, Bangladesh for the period of January 2012 to December 2021. Out of 28,781 and 12,499 surveillance patients in Dhaka and Matlab Hospital, 614 (2.13%) and 278 (2.22%) children were five to nine-years of age, respectively. Among under five children, 2456 from Dhaka hospital and 1112 from Matlab hospital were selected randomly for analysis (four times of five to nine years age children, 1:4). Vomiting, abdominal pain, and dehydrating diarrhoea were significantly higher in older children in comparison to children of less than five years age (p-value <0.05) after adjusting study site, gender, antibiotic use before hospitalization, diarrhoeal duration < 24 hours, intake of oral rehydration fluid at home, parental education, WASH practice and history of cough. Vibrio. cholerae, Salmonella, and Shigella were the common fecal pathogen observed among older children compared to under five after adjusting for age, gender and study site. Although percentage of admitted diarrhoeal children with five to nine years is less than under five years children but they presented with critical illness with different diarrhoeal pathogens. These observations may help clinicians to formulate better case management strategies for children of five to nine years that may reduce morbidity.

Influence of inputs from foreign source regions on daily profiles of Olea pollen at an urban site in the southeast of the Iberian Peninsula

The daily cycle of pollen concentrations reflects its genetic response to environmental conditions. The detailed study of these cycles was used to identify the influence of external sources on local pollen levels. In this work, three different daily profiles (Ci) of Olea pollen concentrations were identified in the city of Alicante (southeastern Spain) using cluster analysis. For this, 2-h data from 2010 to 2015 were used. The percentage frequency, pollen index and mean Olea pollen concentration (in pollen grains∙m−3) for each cluster were: C1 (∼91%, 8797, 26), C2 (∼7%, 4641,179) and C3 (∼2%, 1845, 308). C1 was the predominant pattern throughout the whole MPS, while C2 and C3 were only present in the middle of the MPS. Small variations in pollen concentrations throughout the day were observed for C1, while C2 and C3 showed the highest pollen concentration at ∼04:00 UTC and 10:00 UTC, respectively. C1 represented concentration patterns due to local pollen inputs, being influenced by precipitation events, sea breezes and the recirculation of air pollutants. On the other hand, C2 and C3 were strongly influenced by external pollen inputs from southwestern regions of Spain. The results of this study indicate that external inputs from these regions were associated with exposure of the population to high pollen concentrations for short periods of time. In contrast, inputs from the northwest were associated with exposure to lower pollen concentrations for longer periods of time.

Intimate partner violence, social support and depression in pregnant women in Nigeria

Intimate Partner Violence (IPV) is a risk factor for depression both during and after pregnancy in many communities. The prevalence of domestic violence is common in Kano, Nigeria. Poor social support has been associated with depression. The specific aim of this section was to assess IPV, social support, and association with depression in a group of rural and urban pregnant women. The study was part of a larger study that assessed antenatal women at urban and rural sites using a sociodemographic questionnaire, a Hits Domestic Violence Screening Instrument, a Multidimensional Scale of Perceived Social Support, a MINI International Neuropsychiatric Interview -7, and other instruments. The prevalence of antenatal depression was 23.7%. Fifty percent of the depressed women, as compared to only 7% of nondepressed, had been victims of IPV. IPV was a predictor of antenatal depression in the whole sample and the urban women. Regardless of how long ago IPV occurred, it still served as a significant factor in causing antenatal depression. IPV is a significant predictor of antenatal depression.

Source contribution of black carbon aerosol during 2020–2022 at an urban site in Indo-Gangetic Plain

The extensive emissions of black carbon (BC) from the Indo-Gangetic Plain (IGP) region of India have been well recognized. Particularly, biomass emissions from month-specific crop-residue burning (April, May, October, November) and heating activities (December–February) are considered substantial contributors to BC emissions in the IGP. However, their precise contribution to ambient BC aerosol has not been quantified yet and remains an issue of debate. Therefore, this study aims to fill this gap by quantifying the contribution of these month-specific biomass emissions to ambient BC at an urban site in IGP. This study presents the analysis of BC mass concentrations (MBC) measured for 3 years (2020−2022) in Delhi using an optical photometer i.e., continuous soot monitoring system (COSMOS). A statistical analysis of monthly mean MBC and factors affecting the MBC (ventilation coefficients, air mass back trajectories, fire counts) is performed to derive month-wise contribution due to background concentration, conventional emission, regional transport, crop-residue burning, and heating activities. The yearly mean MBC (5.3 ± 4.7, 5.6 ± 5.0, and 5.3 ± 3.5 μg m−3 during 2020, 2021, and 2022, respectively) remained relatively consistent with repetitive monthly patterns in each year. The peak concentrations were observed from November to January and low concentrations from June to September. Anthropogenic activities contributed significantly to MBC over Delhi with background concentration contributing only 30 % of observed MBC. The percentage contribution of emissions from crop-residue burning varied from 15 % (May) to 37 % (November), while the contribution from heating activities ranged from 25 % (December) to 39 % (January). This source quantification study highlights the significant impact of month-specific biomass emissions in the IGP and can play a vital role in better management and control of these emissions in the region.

Parameterized atmospheric oxidation capacity during summer at an urban site in Taiyuan and implications for O3 pollution control

In recent years, summer ozone pollution shows a significant upward trend in many cities of China, affecting human health and ecosystems. The atmospheric oxidation capacity (AOC) is the core driving force for converting primary pollutants into secondary pollutants. In order to better understand the characteristics of AOC in summer, the comprehensive observation of VOCs (including OVOCs) was conducted at an urban site in Taiyuan from July 20 to August 3, 2020. The parameterized analysis of AOC and ROH was carried out by combining with the simulated photolysis rates (JO1D, JNO2 and JNO3). The results showed that the mean value of MDA8 O3, AOC and ROH were 84.2 ppbv, 2.4 × 107 molecules cm−3 s−1 and 28.3 s−1, respectively. The major reductants of AOC were CO (37.6%), isoprene (21.7%) and formaldehyde (16.8%). Diurnal variations of AOC showed a peak at noon, the major oxidants for AOC were OH (97.7%) and O3 (78.7%) during the daytime and nighttime, respectively. The mean value of MDA8 O3, AOC and VOCs-AOC during the pollution period (MDA8 O3 > 75 ppbv) were 33.0%, 45.0% and 59.3% higher than the non-pollution period, respectively. The OH reactivity ratio of NOx and VOCs indicated that O3 formation occurred under a VOC-limited regime. The backward trajectory analysis showed that VOCs from southwestern airmass had the highest AOC (2.0 × 107 molecules cm−3 s−1), and the domain contributors were isoprene (39.0%), formaldehyde (24.9%), acetaldehyde (9.8%) and ethylene (4.4%). This study could provide some references for regulating AOC to alleviate O3 pollution.

A Foam Line Position Detection Algorithm for A/O Pool Based on YOLOv5

During the biochemical pretreatment process of leachate in urban landfill sites, if the foam in the A/O pool is not promptly addressed, it can lead to overflow, posing hazards to the surrounding environment and personnel. Therefore, a real-time foam line detection algorithm based on YOLOv5x was proposed, which enhances feature information and improves anchor box regression prediction to accurately detect the position of foam lines. Firstly, in the preprocessing stage, employing a rectangular box to simultaneously label the foam line and the edge of the A/O pool within the same region, enhances the feature information of the foam line. Then, the C3NAM module was proposed, which applies weight sparse penalties to attention modules in the feature extraction section, to enhance the capability of extracting foam line features. Subsequently, a B-SPPCSPC module was proposed to enhance the fusion of shallow and deep feature information, addressing the issue of susceptibility to background interference during foam line detection. Next, the Focal_EIOU was introduced to ameliorate the issue of class imbalance in detection, providing more accurate bounding box predictions. Lastly, optimizing the detection layer scale improves the detection performance for smaller targets. The experimental results demonstrate that the accuracy of this algorithm reaches 98.9%, and the recall reaches 88.1%, with a detection frame rate of 26.2 frames per second, which can meet the actual detection requirements of real-world application scenarios.