Contributions Of Various Sources Research Articles

Variations of source-specific risks for inhalable particles-bound PAHs during long-term air pollution controls in a Chinese megacity: Impact of gas/particle partitioning

Gas/particle (G/P) partitioning is a determining factor that drives the behavior of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere. To comprehend the variations and impacts of PAHs G/P partitioning on inhalation risks from different sources, atmospheric PAHs in Chengdu were studied from January 2009 to January 2021. Chengdu's air quality demonstrated improvement, with a noticeable decline in PM10 (from 238 to 103 μg m−3), PM10-bound PAHs mass concentrations (from 0.08 to 0.01 μg m−3), as well as PAHs inhalation non-cancer (from 63.5 to 7.1) and cancer risks (from 6.2 × 10−5 to 7.7 × 10−6). Decreasing trends were also observed in the concentrations of organic carbon (OC) and the values of absorptive G/P partitioning coefficient (Kp, OM) from 2009 to 2020, indicating a slight decrease in the PM absorptive capacity. A positive matrix factorization (PMF) model utilized three distinct datasets: PMFpp (particle-phase PAHs only), PMFtot (total PAHs concentrations), and PMFpp/gas (particle-phase in parallel with gas-phase PAHs). PMFpp and PMFpp/gas provide reasonable source apportionment and source-specific risk results. However, daily variations in source contributions of PMFtot were found to be unreasonable. PMFpp/gas and PMFtot could identify a source of low molecular weight PAHs (LPAHs) related to temperature, and a significantly positive correlation between LPAHs and temperature was discovered. Gas/particle partitioning of PAHs showed a notable impact on source-specific risks associated with coal and biomass combustion (CC&BC). The findings contribute to our understanding of the variation in PAHs G/P partitioning and the PM absorptive capacity resulting from effective air pollution control in China. Additionally, they offer prerequisite information for incorporating semi-volatile organic compounds in source apportionment and source-specific risk assessment.

Spatial and temporal variations in the pollution status and sources of mercury in the Jiaozhou bay

In the past few decades, mercury (Hg) discharged into the coastal bays of China has significantly increased; however, long-term trends regarding the pollution status and sources of Hg in these bays have yet to be clear. Focusing on this issue, surface sediments and core sediments were collected in the Jiaozhou Bay (JZB), a typical bay highly affected by human activities in China, to analyze the concentrations and stable isotopic composition of Hg. Total mercury (THg) concentrations in surface sediment varied from 7 to 163 ng/g, with higher levels located in the eastern JZB, possibly attributed to intensive industrial and population density. THg in sediment cores 14 and 20 displayed fluctuating increasing trends from 1936 to 2019, reflecting the deterioration of Hg pollution. In contrast, THg in sediment core 28 near the river mouth exhibited a declining trend, possibly due to the river dam construction. Using a stable isotope mixing model, contributions of various sources (atmospheric, riverine, and industrial emissions) to Hg in the JZB were estimated. The results showed that industrial emissions were the main source (over 50%) of mercury in the JZB in 2019. Sediment cores recorded an increase in industrial Hg due to early industrialization and Reform and Opening-up before 2000. In addition, sediment core 20 demonstrated a rise in the percentage of riverine Hg due to land reclamation at the bay's mouth during 2000–2007.

Ten years of using key characteristics of human carcinogens to organize and evaluate mechanistic evidence in IARC Monographs on the identification of carcinogenic hazards to humans: Patterns and associations.

Systematic review and evaluation of mechanistic evidence using the Key Characteristics approach was proposed by the International Agency for Research on Cancer (IARC) in 2012 and used by the IARC Monographs Working Groups since 2015. Key Characteristics are 10 features of agents known to cause cancer in humans. From 2015 to 2022, a total of 19 Monographs (73 agents combined) used Key Characteristics for cancer hazard classification. We hypothesized that a retrospective analysis of applications of the Key Characteristics approach to cancer hazard classification using heterogenous mechanistic data on diverse agents would be informative for systematic reviews in decision-making. We extracted information on the conclusions, data types, and the role mechanistic data played in the cancer hazard classification from each Monograph. Statistical analyses identified patterns in the use of Key Characteristics, as well as trends and correlations among Key Characteristics, data types, and ultimate decisions. Despite gaps in data for many agents and Key Characteristics, several significant results emerged. Mechanistic data from in vivo animal, in vitro animal, and in vitro human studies were most impactful in concluding that an agent could cause cancer via a Key Characteristic. To exclude the involvement of a Key Characteristic, data from large-scale systematic in vitro testing programs such as ToxCast, were most informative. Overall, increased availability of systemized data streams, such as human in vitro data, would provide the basis for more confident and informed conclusions about both positive and negative associations and inform expert judgments on cancer hazard.

Hyper-local to regional exposure contrast of source-resolved PM2.5 components across the contiguous United States: implications for health assessment.

Improved understanding of sources and processes that drive exposure contrast of fine particulate matter (PM2.5) is essential for designing and interpreting epidemiological study outcomes. We investigate the contribution of various sources and processes to PM2.5 exposure contrasts at different spatial scales across the continental United States. We consider three cases: exposure contrast within a metro area, nationwide exposure contrast with high spatial resolution, and nationwide exposure contrast with low spatial resolution. Using national empirical model estimates of source- and chemically specific PM2.5 concentration predictions, we quantified the contribution of various sources and processes to PM2.5 exposure contrasts in these three cases. At the metro level (i.e., metropolitan statistical area; MSA), exposure contrasts of PM2.5 vary between -1.8 to 1.4 µg m-3 relative to the MSA-mean with about 50% of within-MSA exposure contrast of PM2.5 caused by cooking and mobile source primary PM2.5. For the national exposure contrast at low-resolution (i.e., using MSA-average mean concentrations), exposure contrasts (relative to the national mean: -3.9 to 3.2 µg m-3) are larger than within an MSA with ~80% of the variation due to secondary PM2.5. National exposure contrast at high resolution (census block) has the largest absolute range (relative to the national mean: -4.7 to 3.7 µg m-3) due to both regional and intra-urban contributions; on average, 65% of the national exposure contrast is due to secondary PM2.5 with the remaining from the primary PM2.5 (cooking and mobile source 26%, other 9%). Our study provides a comprehensive analysis of the sources and processes that contribute to exposure contrasts of PM2.5 across different geographic areas in the US. For the first time on a national scale, we used high spatial resolution source-specific exposure estimates to identify the primary contributors to PM2.5 exposure contrasts. The study also highlights the advantages of different study designs for investigating the health impacts of specific PM2.5 components. The findings provide novel insights that can inform public health policies aimed at reducing PM2.5 exposure and advance the understanding of the epidemiological study outcomes.

Sources and secondary transformation potentials of aromatic hydrocarbons observed in a medium-sized city in yangtze river delta region: Emphasis on intermediate-volatility naphthalene

Aromatic hydrocarbons (AHs) play an important role in the formation of ground-level ozone (O3) and secondary organic aerosols (SOA). Although monoaromatics (MAHs) have been extensively measured in previous studies, the heavy AHs such as 2-ring naphthalene (Nap), a key surrogate of intermediate-volatility organic compounds (IVOCs), were overlooked. Additionally, field observations of AHs are mostly restricted to megacities and limited results have been reported in medium/small-sized cities, which could demonstrate different AH pollution characteristics due to the factors like emission source and population. In this study, sixteen MAHs as well as intermediate-volatility Nap were measured concurrently at six urban sites surrounded by traffic lanes, residential and commercial areas in Wuhu, a medium-sized city in Yangtze River Delta (YRD) region of China, in summertime. During the campaign, the mean concentration of seventeen AHs was 2.85 ± 0.55 ppb (mean ± 95% C.I.). Compared to megacities, lower MAHs but comparable or even relatively higher Nap levels were observed here during the sampling period. Source apportionment revealed that gasoline exhaust and industrial emission were the major contributors to AHs, accounting for 32.2%–52.6% and 20.3%–46.2%, respectively, followed by biomass/coal burning (8.5%–14.2%), solvent utilization (4.5%–13.1%) and diesel engine emission (3.0%–7.3%). Interestingly, diesel engine emission made the largest contribution to Nap, while industrial emission was less significant, suggesting that the source of IVOC species might be different from that of traditional VOCs. Among the measured AHs, Nap ranked the largest and the third-largest contributor to calculated SOA formation potentials (SOAFPs) and O3 formation potentials (OFPs), respectively. Our results highlight the role of intermediate-volatility Nap in the production of SOA and O3 and reveal different source contributions between Nap and MAHs. It is suggested to re-evaluate the contributions of various sources and precursors to urban O3 and SOA after considering the IVOCs.

Record-Breaking heavy rainfall around Henan Province in 2021 and future projection of extreme conditions under climate change

A record-breaking extreme precipitation event that occurred in July 2021 over Henan Province is investigated through observations and reanalysis data. Meanwhile, future extreme precipitation conditions are projected through an ensemble projection model using climate model outputs as input. The long duration, the wide range of influence, the extensive amount of accumulated precipitation, and the high intensity of precipitation are the four major characteristics of this event. Further, the physical causes of this event are explored. First of all, the abnormal northward movement of the western North Pacific Subtropical High is quite significant. Secondly, two slow-moving typhoons are found, which intensify inland moisture transport. Thirdly, after encountering the windward slope, the water vapor is violently lifted and continuously accumulated. Future projections of multiple extreme indices show that more extreme precipitation conditions are expected across the entire Henan Province. In addition, the contribution of various sources to the uncertainty of the ensemble projection are quantified. The global climate model is the primary contributing factor. Meanwhile, the effects explained by the interactive effects between global climate models and shared social-economic pathways cannot be neglected. Our study has constructed an analysis framework called the “Four-in-One” (spatial–temporal feature analysis, causal analysis, future projection, and uncertainty quantification). It provides further insight into changes in local extreme precipitation conditions. The overall framework of this study is equally applicable to investigating other types of extreme events.

Geochemistry of dissolved loads and chemical weathering in the Upper Jhelum River Basin (UJRB) of western Himalayas: Isotopic and chemical constraints

Hydrochemistry and carbon isotopic (δ13CDIC) compositions of dissolved inorganic carbon (DIC) were investigated in the Upper Jhelum River Basin (UJRB) in the western Himalayan region, to better understand the mechanisms and controlling factors of chemical weathering and carbon dynamics. A forward model was used to estimate the contributions of various sources of dissolved loads. Carbonate weathering dominated the riverine solute generation with a contribution of 69.5 ± 5.9%, and ions derived from carbonate weathering show strong chemostatic behavior in response to changes in discharge. Ions derived from silicate weathering demonstrate a significant dilution impact and silicate weathering contributed 8.9 ± 3.1% of the riverine solutes. We estimated the annual discharge weighted weathering rates of carbonate (52.8 t/km2/y) and silicate (12.0 t/km2/y), and then estimated CO2 consumption rates by carbonate weathering (7.0 105 mol/km2/y), silicate weathering (2.2 105 mol/km2/y), and net CO2 consumption flux (6.5 mol/km2/y). The cation flux of 126.5 × 104 t/km2/y accounts for 0.1% of the total cation budget of ocean water. The δ13CDIC values are primarily controlled by carbonate weathering by carbonic acid and show a lower sensitivity than DIC contents in response to various hydrological conditions. However, biological carbon influx during higher temperatures in summer and autumn and evasion to the atmosphere during spring are secondary processes controlling DIC and δ13CDIC in the region. This study provides insights into chemical weathering processes and carbon dynamics, highlights the impacts of hydrological variability that controls the generation and transport of solutes and aids in understanding of the global carbon cycle.

Sources of empowerment and mental health among retired men and women: An ecological perspective

Aims The overarching goal of the present study was to examine the contribution of various sources of empowerment to mental health during retirement with an added emphasis on gender differences. The empowerment sources that were examined corresponded with three distinct ecological systems: (1) Chronosystem—resource gains from the pre- to post-retirement period and satisfaction with the prior working period; (2) Microsystem—marital power dynamics (measured by the division of household labor and decision-making in the marital relationship) and the presence of a confidant; (3) Ontogenetic system—a sense of meaning in one’s life during the retirement period and an assessment of absolute resources. Method The research sample consisted of 160 Israeli retirees (78 women and 82 men) who had retired within the previous eight years. Data were collected by the Panels Research Institute in Israel using the institute’s database of members. Participants completed an online questionnaire accessible via a website link. Statistical processing was performed using ANOVA and hierarchical regression analysis. Results The results indicated that retirees’ reports of resource gains after retirement, their sense of meaning in life, their satisfaction with their working period prior to retirement, and their perceived level of absolute resources were all associated with mental health. Additionally, the more participants (both men and women) rated that the husband was involved in household labor, the better retirees reported their mental health to be. Gender differences were found in regard to some empowerment sources during retirement: retired women reported lower levels of mental health and prior work satisfaction compared to retired men, and men’s assessments of their participation in household labor and decision-making were higher than women’s assessments of their husbands’ involvement. The proportion of men who reported that their wives were their confidants was higher than the proportion of women who reported that their husbands were their confidants. Summary and conclusions Overall, men experienced more sources of empowerment than women during retirement, but findings suggest that men’s emotional dependence on their wives is greater than women’s emotional dependence on their husbands. Based on the study’s findings, recommendations are offered to professionals who work with retirees.

Identify the key emission sources for mitigating ozone pollution: A case study of urban area in the Yangtze River Delta region, China

Ozone (O3) has become the most critical air pollutant in the Yangtze River Delta (YRD) region of China. Research on the O3 formation mechanism and its precursor sources (including nitrogen oxides (NOX) and volatile organic compounds (VOCs)) could provide a theoretical basis for mitigating O3 pollution in this region. In this study, simultaneous field experiments were conducted for air pollutants in a typical urban area (Suzhou) in the YRD region in 2022. The capacity of in-situ O3 formation, O3-NOX-VOCs sensitivities and sources of O3 precursors were analyzed. The results showed that in-situ formation contributed 20.8 % of the O3 concentration in the warm season (April to October) of the Suzhou urban area. Compared with the warm season average, the concentrations of various O3 precursors increased on pollution days. The O3-NOX-VOCs sensitivity was the VOCs-limited regime based on the average concentrations during the warm season. O3 formation was most sensitive to anthropogenic VOCs, of which oxygenated VOCs, alkenes and aromatics were the key species. There was a VOCs-limited regime in spring and autumn, while a transitional regime in summer due to the changes in NOX concentrations. This study considered NOX emission from VOCs sources and calculated the contribution of various sources to O3 formation. The results of VOCs source apportionment showed that diesel engine exhaust and fossil fuel combustion had a dominant proportion, but O3 formation presented significant negative sensitivities to the above two sources because of their high NOX emissions. There were significant sensitivities of O3 formation to gasoline vehicle exhaust and VOCs evaporative emissions (gasoline evaporation and solvent usage). The contribution of VOCs evaporative emissions during the O3 pollution episode was significantly higher than the average; therefore, controlling VOCs evaporative emissions during the O3 pollution episode is critical. These results provide feasible strategies to mitigate O3 pollution.

Routine Estimation of Dissolved Organic Matter Sources Using Fluorescence Data and Linear Least Squares

Dissolved organic matter (DOM) is an important component of the biogeochemistry and ecosystem function of streams and rivers. Unlike inorganic nitrogen nutrients, organic nitrogen (DON) nutrients can vary considerably depending on the contributions of various sources. The properties of DOM in natural waters have been measured using fluorescence spectroscopy, which is inexpensive compared to more sophisticated chemical analysis and is fast enough to enable its use in routine water quality monitoring. However, estimating the contributions of DOM sources to surface waters from fluorescence data in a similarly efficient manner remains an area of active research. In this study, we develop a simple linear regression method for estimating the relative amounts of DOM sources in a stream or river sample. The regression estimates are more accurate than those of previous approaches and are orders of magnitude faster to compute. Codes and data to implement the method are provided for a variety of computing environments to facilitate use for water quality and research applications.

Characteristics of particulate-bound n-alkanes indicating sources of PM2.5 in Beijing, China

Abstract. The characteristics of n-alkanes and the contributions of various sources of fine particulate matter (PM2.5) in the atmosphere in Beijing were investigated. PM2.5 samples were collected at Minzu University of China between November 2020 and October 2021, and n-alkanes in the samples were analyzed by gas chromatography mass spectrometry. A positive matrix factorization analysis model and source indices (the main carbon peaks, carbon preference indices, and plant wax contribution ratios) were used to identify the sources of n-alkanes, to determine the contributions of different sources, and to explain the differences. The n-alkane concentrations were 4.51–153 ng m−3 (mean 32.7 ng m−3), and the particulate-bound n-alkane and PM2.5 concentrations varied in parallel. There were marked seasonal and diurnal differences in the n-alkane concentrations (p<0.01). The n-alkane concentrations in the different seasons decreased in the order of winter > spring > summer > fall. The mean concentration of each homolog was higher at night than in the day in all seasons. Particulate-bound n-alkanes were supplied by common anthropogenic and biogenic sources, and fossil fuel combustion was the dominant contributor. The positive matrix factorization model results indicated five sources of n-alkanes in PM2.5, which were coal combustion, diesel vehicle emissions, gasoline vehicle emissions, terrestrial plant release, and mixed sources. Vehicle emissions were the main sources of n-alkanes, contributing 57.6 %. The sources of PM2.5 can be indicated by n-alkanes (i.e., using n-alkanes as organic tracers). Vehicle exhausts strongly affect PM2.5 pollution. Controlling vehicle exhaust emissions is key to controlling n-alkanes and PM2.5 pollution in Beijing.

Source apportionment of mine contamination across streamflows

Globally, metals released by mine waste represent a challenge for protecting water quality and ecosystems. Understanding metal dispersion in catchments is critical for developing efficient remediation strategies and reducing contamination from mining activities. Efforts to address the issue have been constrained by diffuse sources and variation of source contributions across streamflows. In the UK, metal source apportionment is typically addressed using monitoring strategies with low spatial resolution, which can underestimate the contribution of diffuse sources. In this proof-of-concept study, diffuse sources were accurately apportioned in a mining-impacted catchment in Mid-Wales (UK), using a hydrogeochemical approach with combined continuous tracer injections, gulp injections, and streambed sediment geochemistry. The continuous tracer injections identified a major Zn and Pb point source, diffuse sources due to mine waste tip runoff, and potential groundwater contributions. Variations in source contributions were estimated during high and low flow conditions, with Zn having similar sources and importance across streamflows and Pb being released mainly from overground tips during high flow conditions (22% Pb under low flow and 80% Pb under high flow). The distribution of metal-bearing sediment along the stream sheds light on metal release mechanisms across streamflow conditions. This hydrogeochemical approach for source apportionment, builds on common monitoring methods, and represents a substantial advance in accounting diffuse mine contamination sources, understanding potential metal release mechanisms, and designing remediation strategies.

Nature of Hydrocarbon Fluids at the Fields in the North of Western Siberia: the Geochemical Aspect

The paper presents original results of comprehensive geochemical studies of samples of oils, condensates, gases, core, and cuttings from wells drilled in the north of Western Siberia. The studies involved chromatographic and mass spectrometric determinations of the molecular and isotopic composition of the oils, gases, condensates, and rock extracts. Analysis of the results, considered together with literature data, made it possible to draw conclusions regarding the source of the hydrocarbons and the mechanism of formation of their accumulations. Information on the molecular and isotopic composition of the fluids and the distribution of their accumulations and fields in the sedimentary cover shows that most of them are of polychronic and polygenic origin. Features of the molecular and isotopic composition of the fluids make it possible to evaluate the contribution of various sources to the formation of hydrocarbon accumulations. The composition of their liquid component was formed as a result of the generation of hydrocarbons by the organic matter of Jurassic source rocks. The Lower and Middle Jurassic rocks with non-marine organic matter also made a significant contribution to the formation of the gas component of deposits in the north of Western Siberia, whereas the Cretaceous rocks generated only dry gas and were likely the main source of gas for the giant fields, whose methane has a light carbon isotope composition. The use of the isotopic composition of carbon in combination with molecular parameters makes it possible to clarify the conditions under which a particular field was formed and to elucidate the migration pathways and distances of hydrocarbon fluids to their accumulation sites

EMMTE: An Excel VBA tool for source apportionment of nitrate based on the stable isotope mixing model

Dual nitrate stable isotopes combined with end-member mixing models are typically used to identify nitrate sources in fields of geochemistry and environmental science, which helps to quantitively depict the geochemical behaviors of nitrate and accurately control the sources of nitrate pollution in waters. Recently, various models with different computation principles, working efficiency, and operation difficulty have been developed and applied in the source apportionment of nitrate. In this paper, an end-member mixing model tool on Excel™, namely EMMTE, has been written with Visual Basic for Application (VBA) and built into a macro-enabled Excel™ spreadsheet. Monte Carlo simulation and constraint relative deviation between the observed and the predicted values were included in the working algorithm to solve the mass balance equation. After comparison with the internationally recognized Bayesian framework (mixing stable isotope analysis in R, MixSIAR) in different cases (three practical cases and one virtual case), the preliminary results showed that the contribution of various sources to groundwater nitrate calculated by EMMTE was highly consistent with that by MixSIAR and the performance of EMMTE seemed to be as good as that of MixSIAR as indicated by the higher goodness-of-prediction, lower root-mean-square error, and lower relative deviation. Therefore, EMMTE is applicable in the source apportionment of groundwater nitrate, and might also be extended to other water bodies and mixtures. It provides a simple, feasible, and user-friendly for front-line workers without experience with MixSIAR to quantitively source apportionment of nitrate in waters.

AMBIENT AIR QUALITY MONITORING SYSTEM IN COIMBATORE CITY

Air pollution is dispersion of the particulates, biological molecules, or other harmful materials into the Earth’s atmosphere. Industrialization and urbanization are the two major causes of deteriorating air quality of the major cities in Tamil Nadu, India. Coimbatore is the second and most important commercial and industrial city in India. These industrial activities can add significant levels of heavy metals in the atmosphere. So, regular surveillance and consistent monitoring and modelling of the city would be much imperative. To evaluate the ambient air quality in Coimbatore city the pollutants such as PM10, Suspended Particulate Matter (SPM) and Heavy metals (Cd, Cr, Cu, Pb, Fe, Ni and Zn) were monitored at four locations of the city in this project. The concentration of PM10, SPM and seven heavy metals in the ambient air were estimated and the contributions of various sources were evaluated. The concentration of PM10 and SPM were found to be within the permissible limit. The aim of the project is to develop models, the concentration details of PM10 (Particulate mass). The quality analyzed parameter were compared with the values given by National Ambient Air Quality Standards (NAAQS) Nearly 8 Places in Coimbatore City.

Environmental Noise Measurement Technique and Evaluation of Contribution of a Large Industrial Enterprise to Noise Pollution in the Neighboring Residential Area

Introduction: Strong influence of noise on the urban population is one of the problems of a large city. The main sources of noise include road transport, industrial enterprises, and construction sites. A combined exposure to various sources of noise impedes assessment of their effects on the population. Distinguishing one noise source from another is a difficult measurement task. Objective: To measure noise levels close to a large industrial enterprise given busy traffic nearby, and determine contributions of the industry and road transport to the noise situation in the neighboring residential area. Materials and methods: In summer 2022, noise levels were measured in the vicinity of a large industrial enterprise located in the city of Perm in the daytime and at night at seven and eight sites, respectively, using a sound and vibration meter of the “Assistant” series with an additional “Monitoring” mode. The subsequent processing of chronograms in the “Monitoring” software enabled us to distinguish the noise generated by the industry from that of road traffic using the “Cut” function that removes interferences. Processing of the results using the “energy subtraction” technique allowed quantification of contributions of various sources to the local noise pollution. Results: In this study, noise was measured in a residential area adjacent to an industrial enterprise and the obtained results are provided. Noise levels from the enterprise were determined using a specialized software. The calculated contributions to the noise environment in the residential area vary between 0.035 and 0.603. The conclusion is made about a possible effect produced by noise from the analyzed industrial enterprise on people living on this territory. Conclusion: The effect of industrial noise on people living close to industrial premises is significant only at nighttime.

Identifying individual and spatial drivers of heterogeneous transmission and virulence of malaria in Caribbean anoles

AbstractHeterogeneous distributions are a fundamental principle of ecology, manifesting as natural variability within ecological levels of organization from individuals to ecosystems. In disease ecology, variability in biotic and abiotic factors can result in heterogeneous patterns of transmission and virulence—broadly defined here as the negative consequences of infection. Still, our classic theoretical understanding of disease dynamics comes from models that assume homogeneous transmission and virulence. Here, we test this assumption by assessing the contribution of various sources of individual and spatial heterogeneity to patterns of transmission and sublethal measurements of virulence in two lizard–malaria systems: a three‐parasite assemblage (Plasmodium floridense,Plasmodium leukocytica, andPlasmodium azurophilum) infecting the lizardAnolis gundlachiin the rainforest of Puerto Rico and a single‐parasite system (P. floridense–Anolis sagrei) in Florida. Using a Bayesian model selection framework, we evaluated whether individual host differences (i.e., body size and sex) or spatial variability (i.e., habitat type and local‐scale host spatial structure) drive heterogeneity in the probability of infection or its associated health costs (i.e., body condition, blood chemistry). We found that the probability of infection increases with increasing lizard body size in both systems. However, in Florida, we found the relationship to be subdued in deforested habitats compared to the adjacent urban hydric forests. Furthermore, infection was spatially clustered within sampling sites, with “hot” and “cold” spots across the landscape. Nevertheless, we found no clear evidence of costs of infection on lizard health in any of the measures assessed and hence no grounds for inference regarding heterogeneous virulence. Ultimately, the consistency of our results across systems suggests prominent roles of individual and spatial heterogeneities as driving factors of transmission of vector‐borne diseases.

Dynamic harmonization of source-oriented and receptor models for source apportionment

Millions of premature mortalities are caused by the air pollution of fine particulate matter with aerodynamic diameters less than 2.5 μm (PM2.5) globally per year. To effectively control the dominant emission sources and abate air pollution, source apportionment of PM2.5 is normally conducted to quantify the contributions of various sources, but the results of different methods might be inconsistent. In this study, we dynamically harmonized the results from the two dominant source apportionment methods, the source-oriented and receptor models, by updating the emission inventories of primary PM2.5 from the major sectors based on the Bayesian Inference. An adjoint model was developed to efficiently construct the source-receptor sensitivity matrix, which was the critical information for the updates, and depicted the response of measurements to the changes in the emissions of various sources in different regions. The harmonized method was applied to a measurement campaign in Beijing from January to February 2021. The results suggested a significant reduction of primary PM2.5 emissions in Beijing. Compared with the baseline emission inventory of 2017, the primary PM2.5 emissions from the local residential combustion and industry in Beijing had significantly declined by about 90 % during the investigated period of the year, and the traffic emission decreased by about 50 %. The proposed methods successfully identified the temporally dynamic changes in the emissions induced by the Spring Festival. The methods could be a promising pathway for the harmonization of source-oriented and receptor source apportionment models.

A Study on Financing Pattern of Working Capital in IT Sector Companies in India

Working capital in business is akin to that of heart in human body. Efficient working capital management requires well-balanced funds without which either scarcity of funds will cause obstruction in the smooth functioning of an organization or excess funds will prevent an organization from conducting its operation dexterously. Hence, a great deal of attention must be given to the management of current assets investment in an organization. Management can exercise different sources astutely in financing working capital. In this paper, an attempt has been made to unearth the size of short-term financing pattern used to finance current assets along with the contribution of various sources in the context of the selected five IT sector companies. This paper epitomizes an empirical study of the selected companies in India from diverse perspectives through statistical techniques, tables, secondary data collection strategy accessed through Internet and academic databases viz. literature reviews, website, books, journals, annual reports, etc. from 2012-2013 to 2021-2022. The results of the study show that short-term financing does not meet the full financial requirements of current assets and proportion of various short-term sources in financing working capital requirements has also mixed pattern over the years in the selected units under study.

PM2.5 bound species variation and source characterization in the post-lockdown period of the Covid-19 pandemic in Delhi

This work analyzes the PM2.5 bound highly time-resolved non-refractory and elemental compositions to observe the lag effects of the COVID-19 lockdown in the capital city of India. To the best of our knowledge, this is the first study that focuses on PM2.5 bound highly time-resolved chemical species and source apportionment to assess the contribution of various sources in the post lockdown period (June to September 2020). Here, a comparative scenario between lockdown and unlock periods along with previous years' work is presented. The following eight source profiles are identified from the source apportionment of elements such as power plant (35.6%), dust (25.7%), biomass burning (16.2%), vehicular emission (10%), secondary chloride (4%), waste incineration (3.6%), coal combustion (2.8%) and industrial emission (2.2%). The apportion sources of organic aerosol (OA) yielded two primary factors, primary organic aerosol (POA) and biomass burning organic aerosol (BBOA), and two secondary factors, oxygenated organic aerosols 1 and 2 (OOA-1 and OOA-2). The two oxygenated factors, OOA-1 and OOA-2 dominated the total OA mass concentration with 67.5% and 22% contribution, followed by POA and BBOA with 6.5% and 4%, respectively. The primary factors, POA and BBOA, also showed significant dependency on meteorological conditions during the post lockdown period. A significantly low contribution from the primary factors is seemingly the lagging effect of the lockdown imposed by the government in the earlier months. The meteorological conditions also significantly impacted OOA-1 concentration, which decreased by around 50% in August compared to June 2020. To understand the formation pathways of secondary nitrate and sulphate, NOR and SOR values were calculated and their variation during different RH periods was studied. It was found that photochemical oxidation was the primary pathway of SO2 to SO42− conversion while heterogeneous aqueous pathway was the primary mechanism for nitrate formation during the study period.