Priority Polycyclic Aromatic Hydrocarbons Concentrations Research Articles

Air–plant interaction and air–soil exchange of polycyclic aromatic hydrocarbons in a large human-influenced reservoir in southwest China

The Three Gorges Reservoir (TGR) is totally manmade, strongly influenced by anthropogenic activity, and lies on the upper reaches of Yangtze River. The periodic storage and discharge of water from the Three Gorges Dam could have altered the original air-plant/soil interactions of contaminants in TGR. Herein, paired atmospheric gas–particle, air–plant, and air–soil samples were collected to investigate the air–plant interaction and air–soil exchange of 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs). The air–plant interaction based on McLachlan's framework to our datasets suggests that PAHs were absorbed via gaseous deposition that was restricted by the plant–gas dynamic equilibrium. The equilibrium indicates a dynamic balance between the gaseous phase and plant surface in PAH absorption. The main limiting factor influencing the PAH uptake was the plant species rather than the atmospheric PAH concentration. The air–soil exchange of PAHs exhibited a net volatilization flux of 16.71 ng/m2/d from the soil to the air based on annual average. There was more volatilization and less deposition in summer and more deposition and less volatilization in autumn and winter. The soil serves as a secondary source of atmospheric PAHs. As the first attempt on probing the multi-interface geochemical process of PAHs, this study highlights the influence of manual water level manipulation from the TGD and environmental factors (such as temperature, humidity, and soil properties) on the regional fate of PAHs in the TGR.

Occurrence, source modeling, influencing factors and exposure assessment of polycyclic aromatic hydrocarbons in water sources: A mega-study from mainland China

This study investigates the composition and distribution of 16 priority polycyclic aromatic hydrocarbons (PAHs) in 70 water samples collected from centralized drinking water sources (CDWSs) across 30 provinces (cities) in mainland China. Additionally, water quality and socio-economic data were collected to determine the influencing factors. The study discovered that the total concentrations of 16 priority PAHs (Σ16PAHs) varied from 0.17 to 176.71 ng/L (mean: 56.49 ± 38.58 ng/L). Lakes and reservoirs had significantly higher concentrations of PAHs than groundwater. The primary pollutants were low-molecular-weight (LMW) PAHs, such as phenanthrene, naphthalene, and fluorene. There was a strong correlation between LMW PAHs and Σ16PAHs (p < 0.05). The mean Σ16PAHs in the seven geo-environmental zones were ranked as follows, under the comprehensive influence of emission density, natural, and social environmental factors: Northwest China (78.42 ± 66.96 ng/L) > Northeast China (73.70 ± 33.23 ng/L) > East China (64.35 ± 45.66 ng/L) > North China (50.95 ± 31.87 ng/L) > Southwest China (44.05 ± 32.56 ng/L) > Central China (41.68 ± 19.44 ng/L) > Southern China (40.99 ± 16.54 ng/L). The source modeling analysis revealed that the majority of PAHs came from chemical production and metal smelting (42.36%), as well as from the combustion of coal, wood, and biomass (34.17%), and other mixed sources. In addition, the study found a strong correlation between water quality and socio-economic factors with concentrations of PAHs, indicating that these factors may contribute to the re-enrichment, transport, and transformation of PAHs in overlying water to varying degrees. The mean incremental lifetime cancer risk (ILCR) was lower than the risk threshold. These findings provide scientific references for managing hazardous substances in the aquatic environment.

Levels, distribution, origins, and human health risk evaluation of polycyclic aromatic hydrocarbons in groundwater around a petroleum depot wastewater discharge point

This study is an attempt to assess the influence of the oil storage depot discharges on proximate water sources in Ibadan, southwest Nigeria. Fifteen priority polycyclic aromatic hydrocarbons (PAHs) were examined in a total of 15 water samples (10 groundwater +4 surface water samples) utilizing gas chromatography–mass spectrometry, after extraction of the waters with dichloromethane and clean-up of the extracts. Results revealed that values of overall PAHs in groundwater (GW) and surface water (SW) varied from 0.01 to 3.45 mg/L (mean = 0.42 mg/L) and 0.01 to 0.09 mg/L (mean = 0.05 mg/L), correspondingly. The highest value of ∑15 PAHs (3.45 mg/L) was observed at 24 m to the discharge point. The ring wise distribution pattern of the PAHs in collected water samples follows the order: 2–3 rings >5–6 rings >4 – ring PAHs and low molecular weight (LMW) PAHs accounted for 90.73% relative to HMW (9.27%) in groundwater samples. The diagnostic ratios suggested that the PAHs pollution in water were likely from incomplete combustion of fossil fuels, vehicle emissions and released petroleum effluents from nearby depot. The concentration of carcinogenic PAHs in GW and SW ranged from 1×10−2to 9×10−2 mg/L and 1×10−2to 7×10−2 mg/L, correspondingly, which highlights possible human health risks. The values of hazard index (HI) for the studied samples via the oral ingestion and dermal exposure pathways are less than unity, suggesting no adverse non-carcinogenic health effects. The calculated incremental lifetime cancer risk (ILCR) for adults and children are in the 10−2–10−3 range, implying noteworthy possible carcinogenic health effects to human beings, with children being the most susceptible. Correspondingly, dibenzo [a, h] anthracence (DahA) and Benzo [a] pyrene (BaP) were established to be of greater carcinogenic threats in the waters taken from the study location. The study advocates complete discontinuance of discharge release into the neighboring environment.

High levels of Polycyclic Aromatic Hydrocarbons in the Date Mussel (Lithophaga lithophaga) from Bizerte coast (northern Tunisia): Sources and human health risk implications

The date mussel Lithophaga lithophaga is protected by law in Tunisia. Still, illegal consumption of this luxury seafood has increased over time due to high demand and high prices, which have made the species regularly available in the seafood market of Bizerte, putting wild stocks at risk of decline. To raise public awareness of the risks to human health associated with the consumption of this bivalve, 16 priority polycyclic aromatic hydrocarbons (PAHs) were quantified in the soft tissue of the species, which was collected from two sites of high fishery pressure in the bay and lagoon of Bizerte. Total PAHs concentrations differ significantly between the studied sites ranging from 0.45 to 546.05 μg g−1 d.w., and were associated with port activity and the petroleum industry. The benzo(a)pyrene toxic equivalent factor and excess cancer risk showed both high values exceeding permissible limits in the polluted site. These findings provide valuable information regarding the distribution of PAHs in mussels from wild ecosystems that could be useful to prevent consumer intoxication and improve awareness against illegal harvesting of this species.

Spatial modeling and source identification of PAHs in soils and roadside dusts from Hangzhou, a new first-tier megcity of China

Soil (n = 100) and roadside dust (n = 97) samples across a new first-tier megacity (Hangzhou, East China) were collected to systematically survey the spatial patterns and sources of 16 priority Polycyclic aromatic hydrocarbons (PAHs). The total PAH (Σ16PAH) concentrations in the surface soils exhibited an average of 329 ± 168 ng/g with a range of 67.7–2950 ng/g. 45 % of soils suffered from the weak - heavy PAH contaminations. By contrast, the average concentration of Σ16PAHs in roadside dusts was approximately three times higher than that found in the soils. Within both soil and dust samples, PAHs with a high molecular weight (HMW, 4–6 rings) were the dominant homologs. Spatial lag models revealed that industrial and traffic-related variables significantly influenced the spatial distribution of PAHs in dusts. Furthermore, a positive matrix factorization model indicated that Σ16PAHs in soils and dusts mainly derived from coal-related production/combustion and automobile exhaust emission (65.0 % and 77.9 %, respectively). The isotopic composition analysis conducted on heavily polluted samples further demonstrated that HMW PAHs in these soils and dusts predominantly originated from coal processing and liquid fossil fuel combustion. Overall, the findings of this study suggest that the intensive urban construction and human activities strongly stimulated PAH accumulations in soils and dusts during the rapid urbanization of Hangzhou.

Characteristics and Risk Assessment of PAH Pollution in Soil of a Retired Coking Wastewater Treatment Plant in Taiyuan, Northern China.

We analyzed the soil at the site of a former coking wastewater treatment plant on redeveloped land in Taiyuan, northern China, in an attempt to detect the presence of 16 types of priority polycyclic aromatic hydrocarbons (PAHs) listed by the United States Environmental Protection Agency (US EPA) and evaluate the potential pollution risks. The results show that the total proportion of PAHs in the surface soil of the redeveloped land ranged from 0.3 to 1092.57 mg/kg, with an average value of 218.5 mg/kg, mainly consisting of high-ring (5-6 rings) components. Characteristic ratio analysis indicated that the pollution was mainly related to the combustion of petroleum, coal, and biomasses. The wastewater treatment units operated according to the following treatment train: advection oil separation tank, dissolved air flotation tank, aerobic tank, secondary sedimentation tank, and sludge concentration tank. Our study found that pollution resulting from low-ring PAHs mainly appeared in the advection oil separation tank during the pre-wastewater treatment stage, while medium-ring PAH contamination mainly occurred in the dissolved air floatation tank, aerobic tank, and secondary sedimentation tank during the middle stages of wastewater treatment. High-ring PAH contamination primarily appeared in the sludge concentration tank in the latter stage of wastewater treatment. Based on our assessment of the ecological risk using the Nemerow Comprehensive Pollution Index and the toxicity equivalent factor (TEF) method, we determined that individual PAHs in the study area exceeded acceptable levels and the total amount of pollution was potentially harmful to the ecological environment. In addition, the comprehensive lifetime cancer risk for different populations resulting from exposure to the soil in the study area was determined to be within acceptable limits based on the average PAH concentrations.

Polycyclic aromatic hydrocarbons in suspended particulate matter of a region influenced by agricultural activities in northeast Brazil

Suspended particulate matter (SPM) samples were collected in rainy (2016) and dry (2017) seasons from the Japaratuba River in Northeast Brazil and analyzed the concentration of 16 priority polycyclic aromatic hydrocarbons (PAHs). The results were applied to measure the seasonal variations, spatial distributions, and source apportionment in the estuarine SPM systems. The seasonal variation in total PAHs was not statistically significant, although the highest levels were found in the rainy season, where the total PAHs concentrations in the Japaratuba River ranged from 71 to 1598 ng g−1, with a mean value of 453 ng g−1. In the dry season, the concentrations ranged from 65 to 459 ng g−1, with a mean value of 257 ng g−1. The composition profiles of PAHs at different sites were not significant. At most sampling sites, 5-ring and 6-ring compounds (indeno(1,2,3-cd)pyrene, dibenzo(a,h)anthracene, and benzo(g,h,i)perylene) were the most abundant components, followed by 2-ring and 3-ring compounds (naphthalene and phenanthrene). The use of diagnostic ratios (DR) and principal component analysis (PCA) showed that the PAHs mainly originated from pyrogenic sources. Ecological risk assessment indicated that the PAHs could cause moderate impacts on organisms, suggesting the need for preventive measures.

Contamination of 16 priority polycyclic aromatic hydrocarbons (PAHs) in urban source water at the tidal reach of the Yangtze River.

To explore the occurrence, source, and risk of 16 priority polycyclic aromatic hydrocarbons (PAHs) in urban source water at the tidal reach of the Yangtze River, eighty-nine surface water samples were collected in 8 field campaigns from July 2018 to November 2019. Fifteen of 16 PAHs except for dibenz(a,h)anthracene (DBA) were found in the water. Detection frequencies were observed between 53 and 72% for PAHs with 4 rings, while most of other PAHs were less detected, e.g., benzo(a)pyrene (BaP) in 31% of samples. The total concentrations of 16 priority PAHs reached up to 2.8µg·L-1 and increased during the tidal transitions from flood to ebb. The average concentrations of PAHs in ebb tides were higher than those in flood tides. PAH concentrations and compositions showed great variation with different sampling campaigns, and higher levels and more components were observed in the rainy months and cold months. Those priority PAHs in the tidal water source are mainly from combustion activities (especially fossil fuel combustion), but the contribution from oil spills/leakage is also important in rainy months. High-molecular-weight PAHs in this tidal water source may pose risks to aquatic life, while they pose no carcinogenic risk to human health via ingestion of drinking water.

Seasonality, atmospheric transport and inhalation risk assessment of polycyclic aromatic hydrocarbons in PM2.5 and PM10 from industrial belts of Odisha, India

This study is the first attempt to assess the presence of 16 priority polycyclic aromatic hydrocarbons (PAHs) enlisted by the US Environmental Protection Agency in PM2.5 and PM10 from industrial areas of Odisha State, India. During 2017-2018, bimonthly sampling of PM10 and PM2.5 was carried out for 24h in the industrial and mining areas of Jharsuguda and Angul in Odisha during the pre-monsoon, monsoon, and post monsoon seasons. Highest mean concentration of ∑16PAHs in PM2.5 was observed during the post monsoon (170ng/m3) period followed by pre-monsoon (48ng/m3) and monsoon (16ng/m 3) periods, respectively. A similar trend of ∑16PAHs was also observed in PM10 with higher levels observed during post monsoon (286ng/m3) followed by pre-monsoon (81ng/m3) and monsoon (27ng/m3) seasons. Diagnostic ratios and principal component analysis suggested diesel, gasoline and coal combustion as the major contributors of atmospheric PAH pollution in Odisha. Back trajectory analysis revealed that PAH concentration was affected majorly by air masses originating from the northwest direction traversing through central India. Toxic equivalents ranged between 0.24 and 94.13ng TEQ/m3. In our study, the incremental lifetime cancer risk ranged between 10-5 and 10-3, representing potential cancer risk.

The Variability of the Concentrations of PAHs and PCBs in the Urban Air of Dalian with Ambient Temperature by Semipermeable Membrane Devices Monitoring

Bioavailable air concentration of 18 indicator and dioxin-like polychlorinated biphenyls (PCBs) and 16 EPA priority polycyclic aromatic hydrocarbons (PAHs) in the urban air of Dalian, China were simultaneously measured by semipermeable membrane devices (SPMDs). PCB#28, 52, 101, 105 and 118 were the most abundant PCB congeners in Dalian urban air. Phenanthrene, Fluoranthene and Pyrene were the predominat PAH in the air. PCBs were detected with magnitude ranging from non-detectable to 2151 pg SPMD−1. PAHs ranged from non-detectable to 12464 ng SPMD−1. The linear uptake stages of different PCBs and PAHs with SPMD sampling were different. There were much more PCBs during warmer sampling period than colder sampling period, however, there were a reverse results for PAHs. The concentration of some PCBs and PAHs sequestrated by SPMD (C SPMD) in the air has linear correlation with the reciprocal of the average ambient atmospheric temperature (T). The C SPMD of PAHs had negative correlation with T, while the C SPMD of the PCBs had positive correlation with T. The above research results provide basic reference data for the promotion and application of SPMD passive samplers.

Polycyclic aromatic hydrocarbons in the snow cover of the northern city agglomeration

Sixteen priority polycyclic aromatic hydrocarbons (PAHs) were qualitatively and quantitatively assessed by high-performance liquid chromatography with fluorescence detection in snow samples collected at 46 sites of Arkhangelsk as a world’s largest city above 64 degrees north latitude. The average, maximum and minimum PAH concentrations in snow were 168, 665, and 16 ng/kg, respectively. The average toxic equivalent value in benzo(a)pyrene units was 3.6 ng/kg, which is three-fold lower than the established maximum permissible concentration and considered an evidence of a low/moderate level of snow pollution with PAHs. The pollution origin was assessed using specific markers based on PAHs ratios in the studied samples. The pyrogenic sources of PAH emission were predominate, whereas the significant contributions from both transport and solid fuel combustion were observed. Benzo(a)pyrene concentrations are highly correlated with the levels of other PAHs with higher molecular weights.

The effect of combined pollution by PAHs and heavy metals on the topsoil microbial communities of Spolic Technosols of the lake Atamanskoe, Southern Russia.

The contamination with organic and inorganic pollutants changes significantly soil microbial community structure. These shifts indicate anthropogenic pressure and help to discover new possibilities for soil remediation. In this study, the microbial community structure of Spolic Technosols formed at the territory of a former industrial sludge reservoir near the Kamensk-Shakhtinsky (Southern Russia) was studied using a metagenomics approach. The studied soils contain high concentrations of heavy metals (HM) (up to 72,900mgkg-1) and 16 priority polycyclic aromatic hydrocarbons (PAHs) (up to 6670mgkg-1). Its microbial communities demonstrate an excellent adaptability level reflected in their complexity and diversity. As shown by the high values of alpha diversity indices (Shannon values up to 10.1, Chao1 values from 1430 to 4273), instead of decreasing quantitatively and qualitatively on the systemic level, microbial communities tend to undergo complex redistribution. Regardless of contamination level, the share of Actinobacteria and Proteobacteria was consistently high and varied from 20 to 50%. Following the results of the Mann-Whitney U test, there were significant changes of less abundant phyla. The abundance of oligotrophic bacteria from Gemmatimonadetes and Verrucomicrobia phyla and autotrophic bacteria (e.g., Nitrospira) decreased due to the high PAH's level. And abundance of Firmicutes and amoebae-associated bacteria such as TM6 and soil Chlamydia increased in highly contaminated plots. In the Spolic Technosols studied, the influence of factors on the microbial community composition decreased from PAHs concentration to soil characteristics (organic carbon content) and phylum-phylum interactions. The high concentrations of HMs influenced weakly on the microbial community composition.

Effects of architecture structure on volatile organic compound and polycyclic aromatic hydrocarbon diffusion in Singapore's Integrated Transport Hubs

Millions of passengers wait for buses at Integrated Transport Hubs (ITH) daily in metropolitan cities. Environmental exposure and associated risk for passengers is of great public concern. In this study, eight volatile organic compounds (VOCs) and the 16 EPA priority polycyclic aromatic hydrocarbons (PAHs) were analyzed in airborne samples collected from indoor waiting areas (Indoor) and bus parks of nine Singapore ITH, which comprises of two types of architectural structure (i.e., fully sheltered and open/partially enclosed). The median concentrations of total VOCs (TVOCs), total gaseous PAHs (TgPAHs) and total airborne particles-adsorbed PAH (TpPAHs) concentrations in Indoor were 30.42 μg/m3, 18.99 ng/m3 and 1.38 ng/m3; respectively. A strong correlation (r ≥ 0.75, p < 0.001) was observed between Indoor and bus parks air compounds. The “Indoor” to bus park pollutant concentration ratio (I/B ratio) showed lower values in the bus interchanges with fully sheltered bus parks (TVOCs: 0.98; TgPAHs: 0.76; TpPAHs: 0.71) than those with open/partially enclosed ones (TVOCs: 1.28; TgPAHs: 1.31; TpPAHs: 0.90). This result suggests that fully sheltered structure may cause the accumulation of air pollutants. The daily VOC and PAH exposure for commuters were further estimated by considering inhalation and dermal doses using Monte Carlo simulation (n = 100,000). Overall, the result showed that the risk is still within international guideline values. In sum, the effect of architecture structure on the migration of air pollutants should be taken into consideration in future transport hub design to reduce pollutant exposure to commuters.

Polycyclic Aromatic Hydrocarbons in Houston Parks After Hurricane Harvey.

Unprecedented inland precipitation and catastrophic flooding associated with Hurricane Harvey potentially redistributed contaminants from industrial sites and transportation infrastructure to recreational areas that make up networks of green infrastructure, creeks, and waterways used for flood control throughout the Greater Houston Area. Sediment samples were collected in parks located near the Buffalo Bayou watershed 1 week after Hurricane Harvey made landfall and again 7 weeks later. Total concentrations of the U.S. Environmental Protection Agency's (EPA's) 16 priority polycyclic aromatic hydrocarbons (PAHs) were measured in each sample at both time points. Diagnostic ratios were calculated to improve understanding of potential sources of PAHs after flooding. Diagnostic ratios suggest vehicular traffic to be a potential source for PAHs in parks. Although the concentrations of PAHs in all samples were below EPA actionable levels, given that no background values were available for comparison, it is difficult to quantify the impact flooding from Hurricane Harvey had on PAH concentrations in Houston parks. However, given the high frequency of flooding in Houston, and the concentration of industrial facilities and transportation infrastructure adjacent to recreation areas, these data demonstrate that PAHs were still present after unprecedented flooding. This study may also serve as a baseline for future efforts to understand the environmental health impacts of disasters.

Pollution level and health risk assessment of polycyclic aromatic hydrocarbons in marine fish from two coastal regions, the South China Sea

Marine fishes are consumed in large quantities by humans as nutritious food. However, the intake of fish polluted by chemicals may pose a severe threat to human health. This study measured the concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) in the muscles of 22 species of marine fish from two coastal regions, i.e., Tanmen and Zhuhai, identified the source of PAHs, and assessed the human health risk by dietary exposure. Total PAH (Σ16PAHs) levels in Tanmen and Zhuhai fish were in the range of 24.29–684.83 ng g−1 dry weight (dw) and 13.74–42.59 ng g−1 dw, averaging 161.46 ng g−1 dw and 31.21 ng g−1 dw, respectively. Compared with other regions in the world, PAH concentrations in Tanmen fish were at median levels, and Zhuhai fish were at low levels. Low molecular weight PAHs (with 2- and 3-rings) were the predominant compounds detected. Molecular diagnostic ratios suggested that PAHs in Tanmen mainly originated from petrogenic sources such as vessel operations or tanker accidents, while Zhuhai fish were mainly polluted by pyrolytic sources such as combustion of coal and wood. The human health risk assessment results indicated that the risk of PAH intake via fish consumption from Zhuhai was negligible, while five species from Tanmen may pose potential health risks to local residents.

Polycyclic Aromatic Hydrocarbons and Potentially Toxic Elements in Soils of the Vicinity of the Bulgarian Antarctic Station “St. Kliment Ohridski” (Antarctic Peninsula)

The investigation conducted was dialed to quantitative and qualitative evaluation of 15 priority polycyclic aromatic hydrocarbons (PAHs) and Potentially Toxic Elements (Cu, Pb, Zn, Cd, Ni, and Cr) is soils and cryoconites on “St. Kliment Ohridski” Antarctic station territory and its vicinities. Estimation of benzo(a)pyrene (BaP)–equivalents, PAHs and different PAHs isomer pair ratios were used for identification of general toxicity, nature and origin of individual PAHs and their groups. Total concentrations of PAHs in BaP–equivalents showed, that ∑15PAH of all selected points was higher than the threshold concentration (20 μg × kg−1–Russian environmental legislation) for benzo(a)pyrene. Different PAHs isomer ratios showed the natural (petrogenic) source of PAHs at all soils examples (except Cryosol Toxic Transportic). The maximum content among potentially toxic elements was recorded for Zn (75.7 mg × kg−1 at L26), the minimum for Cd (0.201 mg × kg−1 at L1A). Average concentrations of potentially toxic elements are generally lower compared to the results of previous studies. Application of Igeo index, characterizes the majority of the studied soils as unpolluted or practically unpolluted. Data obtained indicates that there is no current critical anthropogenic load on the environmental components of the landscapes investigated.

Temporal-spatial survey of PAHs and PCBs in the Atlantic Iberian northwest coastline, and evaluation of their sources and risks for both humans and aquatic organisms

Herein, sixteen priority sixteen priority polycyclic aromatic hydrocarbons (PAHs) and seven polychlorinated biphenyls (PCBs), considered seawater quality indicators, were quantified in four beaches of the Iberian (Portuguese) northwest coastline, including one ornithological reserve. These seashores are close to an important industrial region and a harbour. Water samples were extracted for PAHs and PCBs in their aqueous phase (DAP) and suspended particulate matter (SPM) and analysed by GC-MS/MS. Annual average concentrations reached ∼8 ng/L (DAP) and ∼100 ng/g dw (SPM) for PAHs and ∼3 ng/L (DAP) and ∼19 ng/g dw (SPM) for PCBs. PAHs and PCBs had fluctuations suggestive of seasonality. The possible origins of PAHs point to pyrogenic (forest fires) and petrogenic activities linked to maritime transports. The source(s) of PCBs appear to be related with leaks from waste sorting centres located in the vicinity of the sampling sites, together with the burning of contaminated materials. Toxic equivalents (TEQs) suggested a low carcinogenic potential for PAHs in seawater samples (∼0.3 ng/L and ∼4 ng/g dw, for DAP and SPM). Evaluation of risk coefficients for Σ16 PAHs revealed "Low-risk" of both matrices in all sampling areas. PCBs thyroid toxicity equivalents (TEQs-TH), suggested a low impact on biota (∼7.0E-05 ng/L and ∼5.2E-04 ng/g dw, for DAP and SPM). However, in vivo acute assays with Artemia salina exposed to environmental concentrations of PAHs, PCBs, and mixtures, confirmed the theoretical approach, showing that this coastline is not "Risk-free". This fact calls for further toxicological approaches to fully understand the risks posed by these compounds locally.

Distribution and the use of diagnostic ratios for source investigation in urban soils of the Yenagoa City, Bayelsa State, Nigeria

Yenagoa is a non-industrialized city. This work aims to investigate the distribution, content and source of the sixteen United State Environmental Protection Agency (USEPA) priority polycyclic aromatic hydrocarbons (PAHs) in urban soils of the Yenagoa, Bayelsa State, Nigeria. The PAH concentrations in the urban soil samples were performed using GC–MS method. The Swali market axis of the city had the highest concentration (∑PAHs). The burden of low molecular weight (LMW) PAHs follows a decreasing order: Phenanthrene > acenaphthene>cenaphthylene>naphthalene> anthracene>fluorine and while the burden of high molecular weight (HMW) PAHs follows the decreasing order: Pyrene> Dibenzo (a,h) anthracene > indeno [1,2,3-cd] pyrene (InP> Chrysene> Fluoranthene> Benzo(a)anthracene> Benzo(k)fluoranthene> Benzo(b)fluoranthene. PAH fingerprint ratios for determining both petrogenic and pyrogenic (pyrolytic) PAH accumulation was employed. The Ph/An ratio for the soil samples were 2.49, 3.47, 0.613, 1.59, 1.99 and 2.44 respectively. This may be indicative of pyrogenic (pyrolytic) origin. Ind(1,2,3-cd)P and DbahA were high in the soils, this may indicate a major concern for carcinogenic risk and demands an urgent attention from policy makers and the government.

Characterization, Sources, and Health Risks of PM2.5-bound PAHs During Autumn and Winter in Luoyang City

In this study, PM2.5 samples were collected synchronously at Gaoxin and Linxiao in Luoyang City during autumn and winter (4 October 2018 to 30 January 2019). Sixteen priority polycyclic aromatic hydrocarbons (PAHs) associated with fine particulate matter were analyzed by gas chromatography mass spectrometry (GC-MS). The concentrations and composition characteristics of the PAHs on clean and polluted days were studied. Diagnostic ratio analysis and principal component analysis (PCA) were used to identify the emission sources of PM2.5-bound PAHs and the equivalent carcinogenic concentration of benzo[a]pyrene (BaP) and incremental lifetime cancer risks (ILCRs) model were applied to evaluate health risks. During the sampling period, the concentrations of PAHs at Gaoxin and Linxiao ranged 24.33-90.26 ng·m-3 and 23.81-76.99 ng·m-3, respectively. With the increase in PM2.5 pollution, PAH concentrations increase significantly (the mean PAH concentration on polluted days was approximately 1.3 times higher than during clean days). PAH profiles at different polluting levels were similar; 4-ring PAHs (43%-48%) > 5-6 ring PAHs (32%-35%) > 2-3-ring PAHs (20%-22%). Diagnostic ratios and PCA demonstrated that PAHs in the study area were mainly derived from combustion sources including coal combustion, biomass burning, and motor vehicle emissions. The coal combustion was the main pollution source in the study area (clean days=49.28%-56.38%, polluted days=49.44%-60.60%). The results of the equivalent carcinogenic concentration of benzo[a]pyrene (BaP) and ILCR model revealed that the human health risk on polluted days was higher. Moreover, the cancer risks from adult exposure to PAHs were higher than those child exposure, which has an acceptable level of risk (<10-6).

Spatial-temporal variations and transport process of polycyclic aromatic hydrocarbons in Poyang Lake: Implication for dry–wet cycle impacts

The dry-wet cycles of the lake-catchment system may affect the spatial-temporal variations and transport of specific volatile organic compounds. In this study, we analyzed 16 priority polycyclic aromatic hydrocarbons (PAHs) in water, suspended particulate matter (SPM), air, soil and sediment in the Poyang Lake, which is the largest freshwater lake in Southeast China. The samples were collected from intertidal zone of the Poyang Lake, in both the dry and wet seasons, corresponding to the exposure and submersion periods, respectively. Concentrations of target PAHs in air, water, SPM and sediments were 0.8–13.5 ng/m3, 5.1–62.0 ng/l, 117–4651 ng/g and 16.4–775 ng/g, respectively. Concentrations of PAHs in sediments were found to be significantly related to total organic carbon and water content (p < 0.01). Compared to the sediment samples, the low molecular weight (LMW) PAHs (2–3 rings) accounted for greater proportions in water, SPM and air. Results suggest that the occurrences of PAH species are affected by their lipophilic properties. Molecular diagnostic ratios of PAH isomers in multimedium indicated that PAH presence in the Poyang Lake were attributed to both pyrogenic and petrogenic sources, and source contributions in different medium were shown to vary. Sediment-water and soil-air exchanges showed that the sediment plays a role of secondary emission sources for most LMW PAHs, and some high molecular weight PAHs (e.g., BghiP, IcdP and DahA) had different transmission directions in the alternate process of exposure and submersion. These findings provide a better understand of migration mechanism among the air, water body (including water and SPM) and sediment PAHs driven by dry-wet cycles.