Particle Bound Metals at Major Intersections in an Urban Location and Source Identification Through Use of Metal Markers

Health risk assessment of PM2.5 and PM2.5-bound trace elements in Pretoria, South Africa

Exposure to outdoor air pollutants poses a risk for both non-carcinogenic and carcinogenic respiratory disease outcomes. A standardized health risk assessment (US EPA) utilizes air quality data, body mass and breathing rates to determine potential risk. This health risk assessment study assesses the hazard quotient (HQ) for total PM_2.5 and trace elemental constituents (Br, Cl, K, Ni, S, Si, Ti and U) exposure in Pretoria, South Africa. The World Health Organization (WHO) air quality guideline (5 µg m^-3) and the yearly South African National Ambient Air Quality Standard (NAAQS) (20 µg m^-3) were the references dosages for total PM_2.5. A total of 350 days was sampled in Pretoria, South Africa. The mean total PM_2.5 concentration during the 34-month study period was 23.2 µg m^-3 (0.7-139 µg m^-3). The HQ for total PM_2.5 was 1.17, 3.47 and 3.78 for adults, children and infants. Non-carcinogenic risks for trace elements K, Cl, S and Si were above 1 for adults. Seasonally, Si was the highest during autumn for adults (1.9) and during spring for S (5.5). The HQ values for K and Cl were highest during winter. The exposure to Ni posed a risk for cancer throughout the year and for As during winters.

Impact of COVID‐19 lockdown on the elemental profile of PM 10 present in the ambient aerosol of an educational institute in Kolkata, India

Reduction in air pollution level was prime observation during COVID‐19 lockdown globally. Here, the study was conducted to assess the impact of lockdown on the elemental profile of PM₁₀ in ambient aerosol to quantify the elemental variation. To quantify the variation, phase‐wise sampling of air pollutants was carried out using the gravimetric method for PM₁₀, while NO₂ and SO₂ were estimated through the chemiluminescence and fluorescent spectrometric method respectively. The elemental constituents of PM₁₀ were carried out using an Inductively Coupled Plasma Optical Emission Spectrometer and their source apportionment was carried out using the Positive Matrix Factorization model. The results showed that PM₁₀, NO₂ and SO₂ reduced by 86.97%, 83.38%, and 88.60% respectively during the lockdown sampling phase. The highest mean elemental concentration reduction was found in Mn (97.47%) during the lockdown. The inter‐correlation among the pollutants exhibited a significant association indicating that they originate from the same source. The metals like Mn and Cu were found at a higher concentration during the lockdown phase corresponding to vehicular emissions. The comparative analysis of the elemental profile of PM₁₀ concluded that the lockdown effectuated in reduction of the majority of elements present in an aerosol enveloping metropolitan like Kolkata.

Determination and assessment of elemental concentration in the atmospheric particulate matter: a comprehensive review

The elemental concentrations of atmospheric particulate matter (PM) have a detrimental effect on human health in which some elemental species have carcinogenic nature. In India, significant variations have found in the practices adapted from sampling to analysis for the determination and assessment of the elemental concentration in PM. Therefore, Indian studies (2011-2020) on the related domain are summarized to impart consistency in the field and laboratory practices. Further, a comparative analysis with other countries has also been mentioned in the relevant sections to evaluate its likeness with Indian studies. To prepare this study, literature has been procured from reputed journals. Subsequently, each step from sampling to analysis has thoroughly discussed with quality assurance and control (QA/QC) compliance. In addition, a framework has been proposed that showed field and laboratory analysis in an organized manner. Consequently, this study will provide benefit to novice researcher and improve their understanding about the related subject. Also, it will assist other peoples/bodies in framing the necessary decisions to carry out this study.

Assessment of Pollution and Health Risks of Heavy Metals in Particulate Matter and Road Dust Along the Road Network of Dhanbad, India

BACKGROUND

The rise in particulate matter (PM) concentrations is a serious problem for the environment. Heavy metals associated with PM₁₀, PM_2.5, and road dust adversely affect human health. Different methods have been used to assess heavy metal contamination in PM₁₀, PM_2.5, and road dust and source apportionment of these heavy metals. These assessment tools utilize pollution indices and health risk assessment models.

OBJECTIVES

The present study evaluates the total mass and average concentrations of heavy metals in PM₁₀, PM_2.5, and road dust along selected road networks in Dhanbad, India, analyzes the source apportionment of heavy metals, and assesses associated human health risks.

METHODS

A total of 112 PM samples and 21 road dust samples were collected from six stations and one background site in Dhanbad, India from December 2015 to February 2016, and were analyzed for heavy metals (iron (Fe), lead (Pb), cadmium (Cd), nickel (Ni), copper (Cu), chromium (Cr), and zinc (Zn)) using atomic absorption spectrophotometry. Source apportionment was determined using principal component analysis. A health risk assessment of heavy metal concentrations in PM₁₀, PM_2.5, and road dust was also performed.

RESULTS

The average mass concentration was found to be 229.54±118.40 μg m^-3 for PM₁₀ and 129.73 ±61.74 μg m^-3 for PM_2.5. The average concentration of heavy metals was found to be higher in PM_2.5 than PM₁₀. The pollution load index value of PM₁₀ and PM_2.5 road dust was found to be in the deteriorating category. Vehicles were the major source of pollution. The non-carcinogenic effects on children and adults were found to be within acceptable limits. The heavy metals present in PM and road dust posed a health risk in the order of road dust> PM₁₀> and PM_2.5. Particulate matter posed higher health risks than road dust due to particle size.

CONCLUSIONS

The mass concentration analysis indicates serious PM₁₀ and PM_2.5 contamination in the study area. Vehicle traffic was the major source of heavy metals in PM₁₀, PM_2.5, and road dust. In terms of non-carcinogenic risks posed by heavy metals in the present study, children were more affected than adults. The carcinogenic risk posed by the heavy metals was negligible.

COMPETING INTERESTS

The authors declare no competing financial interests.

The Complex Issue of Urban Trees—Stress Factor Accumulation and Ecological Service Possibilities

This review paper is the first that summarizes many aspects of the ecological role of trees in urban landscapes while considering their growth conditions. Research Highlights are: (i) Plant growth conditions in cities are worsening due to high urbanization rates and new stress factors; (ii) Urban trees are capable of alleviating the stress factors they are exposed to; (iii) The size and vitality of trees is related to the ecological services they can provide. Our review shows, in a clear way, that the phenomenon of human-related environmental degradation, which generates urban tree stress, can be effectively alleviated by the presence of trees. The first section reviews concerns related to urban environment degradation and its influence on trees. Intense urbanization affects the environment of plants, raising the mortality rate of urban trees. The second part deals with the dieback of city trees, its causes and scale. The average life expectancy of urban trees is relatively low and depends on factors such as the specific location, proper care and community involvement, among others. The third part concerns the ecological and economic advantages of trees in the city structure. Trees affect citizen safety and health, but also improve the soil and air environment. Finally, we present the drawbacks of tree planting and discuss if they are caused by the tree itself or rather by improper tree management. We collect the latest reports on the complicated state of urban trees, presenting new insights on the complex issue of trees situated in cities, struggling with stress factors. These stressors have evolved over the decades and emphasize the importance of tree presence in the city structure.

Particle size dynamics and risk implication of atmospheric aerosols in South-Asian subcontinent

Presented here are size-resolved aerosol measurements conducted using cascade impactor set at breathing zone in indoor-outdoor residential microenvironments. PM_2.5 contributed about 64-80% of PM₁₀ in which over 29% of mass was shared by PM_0.25. Total PM concentration varied from 261 ± 22 μg/m³ (indoors) to 256 ± 64 μg/m³ (outdoors) annually; whilst summer and monsoon demonstrated 1.2- and 1.9- times lower concentration than winters. The measured metals ranged between 9% (in PM_2.5-10) to 18% (in PM_1-2.5) of aerosol concentration; whereby crustal elements dominated coarse fractions with relatively higher proportion of toxic elements (Ba, Cd, Co, Cr, Cu, Ni) in ultrafine range. Considering lognormal particle size distribution (PSD), accumulation mode represented the main surface area during entire monitoring period (Mass Median Aerodynamic Diameter (MMAD) < 1). PSD of metal species reflected their different emission sources with respect to season integrated samples. High air exchange conditions permitted the shift of indoor PSD pattern closer to that of outdoor air while low ventilation in winters reflected modal shift of metals (Pb, Mg. K) towards larger size particles. Relative surge towards smaller diameter size of soluble metal fraction relative to the total concentration of toxic elements was noted on an annual basis with high infiltration capacity of smaller size particulates (Finf =1.36 for ultrafine particles in summers) identified through indoor-outdoor regression analysis. Principal Component Analysis identified sources such as vehicular traffic, combustion, crustal emission with activities viz. smoking and those involving use of electric appliances.

Speciation of organic fractions does matter for aerosol source apportionment. Part 2: Intensive short-term campaign in the Paris area (France)

The present study aimed at performing PM₁₀ source apportionment, using positive matrix factorization (PMF), based on filter samples collected every 4h at a sub-urban station in the Paris region (France) during a PM pollution event in March 2015 (PM₁₀>50μgm^-3 for several consecutive days). The PMF model allowed to deconvolve 11 source factors. The use of specific primary and secondary organic molecular markers favoured the determination of common sources such as biomass burning and primary traffic emissions, as well as 2 specific biogenic SOA (marine+isoprene) and 3 anthropogenic SOA (nitro-PAHs+oxy-PAHs+phenolic compounds oxidation) factors. This study is probably the first one to report the use of methylnitrocatechol isomers as well as 1-nitropyrene to apportion secondary OA linked to biomass burning emissions and primary traffic emissions, respectively. Secondary organic carbon (SOC) fractions were found to account for 47% of the total OC. The use of organic molecular markers allowed the identification of 41% of the total SOC composed of anthropogenic SOA (namely, oxy-PAHs, nitro-PAHs and phenolic compounds oxidation, representing 15%, 9%, 11% of the total OC, respectively) and biogenic SOA (marine+isoprene) (6% in total). Results obtained also showed that 35% of the total SOC originated from anthropogenic sources and especially PAH SOA (oxy-PAHs+nitro-PAHs), accounting for 24% of the total SOC, highlighting its significant contribution in urban influenced environments. Anthropogenic SOA related to nitro-PAHs and phenolic compounds exhibited a clear diurnal pattern with high concentrations during the night indicating the prominent role of night-time chemistry but with different chemical processes involved.

Speciation of organic fraction does matter for source apportionment. Part 1: A one-year campaign in Grenoble (France)

PM₁₀ source apportionment was performed by positive matrix factorization (PMF) using specific primary and secondary organic molecular markers on samples collected over a one year period (2013) at an urban station in Grenoble (France). The results provided a 9-factor optimum solution, including sources rarely apportioned in the literature, such as two types of primary biogenic organic aerosols (fungal spores and plant debris), as well as specific biogenic and anthropogenic secondary organic aerosols (SOA). These sources were identified thanks to the use of key organic markers, namely, polyols, odd number higher alkanes, and several SOA markers related to the oxidation of isoprene, α-pinene, toluene and polycyclic aromatic hydrocarbons (PAHs). Primary and secondary biogenic contributions together accounted for at least 68% of the total organic carbon (OC) in the summer, while anthropogenic primary and secondary sources represented at least 71% of OC during wintertime. A very significant contribution of anthropogenic SOA was estimated in the winter during an intense PM pollution event (PM₁₀>50μgm^-3 for several days; 18% of PM₁₀ and 42% of OC). Specific meteorological conditions with a stagnation of pollutants over 10days and possibly Fenton-like chemistry and self-amplification cycle of SOA formation could explain such high anthropogenic SOA concentrations during this period. Finally, PMF outputs were also used to investigate the origins of humic-like substances (HuLiS), which represented 16% of OC on an annual average basis. The results indicated that HuLiS were mainly associated with biomass burning (22%), secondary inorganic (22%), mineral dust (15%) and biogenic SOA (14%) factors. This study is probably the first to state that HuLiS are significantly associated with mineral dust.

An assessment of polyurethane foam passive samplers for atmospheric metals compared with active samplers

In this study, we conducted an assessment of polyurethane foam (PUF) passive sampling for metals combining active sampling. Remarkably, we found that the metals collected in the passive samples differed greatly from those collected in active samples. By composition, Cu and Ni accounted for significantly higher proportions in passive samples than in active samples, leading to significantly higher uptake rates of Cu and Ni. In assessing seasonal variation, metals in passive samples had higher concentrations in summer (excluding Heshan), which differed greatly from the pattern of active samples (winter > summer), indicating that the uptake rates of most metals were higher in summer than in winter. Overall, due to the stable passive uptake rates, we considered that PUF passive samplers can be applied to collect atmospheric metals. Additionally, we created a snapshot of the metal pollution in the Pearl River Delta using principal component analysis of PUF samples and their source apportionment.