Sources Of PAHs Research Articles

Understanding Polycyclic Aromatic Hydrocarbon Accumulation in Road Dust of a Tropical Megacity in Southern Vietnam: Implications on Environmental Management

This study investigated the characteristics of 23 PAHs in road dust from various areas in Ho Chi Minh City (HCMC), focusing on spatial distribution, pollution levels, human health risks, and source apportionment. PAH levels in urban samples (residential and industrial sites) ranged from 208 to 7665 (μg/kg), significantly higher than background levels (135±42.2μg/kg). A west>east gradient in PAH distribution, particularly in crowded traffic intersections, suggested traffic activities as a major source. Pollution load indices indicated moderate to very high pollution in most urban sites. Incremental lifetime cancer risk assessments showed moderate to high risks, especially for children. Statistical analyses and diagnostic ratios identified vehicular emissions as the primary PAH sources, with Positive Matrix Factorization analysis attributing 46.6% to gasoline vehicles, 21.9% to diesel vehicles and petroleum evaporation, 18.3% to tar oil, and 10.2% to coal burning. This study fills a significant information gap on PAHs in road dust, which has not been previously reported in southern Vietnam, specifically in HCMC-a dynamic and rapidly developing city in Southeast Asia. The findings highlight the need for synchronized management and technical solutions to mitigate PAH risks in road dust, contributing valuable knowledge on PAH accumulation in a major southern city of Vietnam.

Chemical Fingerprinting, PAHs Characterization and Ecological Risks of Carcinogenic PAHs in Surficial Sediments of Egi Crude Oil Producing Communities, Niger-Delta, Nigeria

In order to do PAHs rings analysis, its source identification, extent to which cPAHs present and what kind of ecological risk they pose, the surface sediments from various freshwaters in the Egi crude oil producing cities in the Niger Delta, Nigeria were analyzed. Sediments collected from the research areas for PAHs loadings (in mg/kg dry weight) ranged from 0.020 to 1.790, 0.050 to 1.880, and 0.020 to 1.640, respectively for Obite, Obagi, and Ibewa cluster areas, as measured by gas chromatography-mass spectrometer. In these clusters, the respective average concentration of the three dominant carcinogenic PAHs were Indeno(1,2,3-cd)pyrene (1.170.0mg/kg), Dibenz[a,h]anthrancene (0.870.0 mg/kg), and Dibenz[a,h]anthrancene (1.3670 mg/kg) for Ibewa, Obagi and Obite cluster areas. The findings showed that dominant PAHs rings are of high molecular weight (HMW) PAHs in these sediments are, 5 member rings, which are benzo(b)fluoranthene, Benzo(k)fluoranthene, and Benzo(a)pyrène, and 6-member ring which are, Indeno(1,2,3-cd)pyrene, Dibenz[a,h]anthrancene, and Benzo[ghi] perylene, respectively. Their fingerprints points majorly to pyrogenic sources, combustion of coal, biomass, petroleum, and other related anthropogenic petroleum activities as the primary source of PAHs in the environment. Notably, the RQNCs and RQMPCs for single PAHs molecule are both less than 1, it means the contamination it generates is considered of low ecological risk. Again, the research area experiences frequent flooding, it is believed that this contributes to the low ecological risk of PAHs chemical pollution. Consequently, the area is deemed to be quite safe.

Occurrence, characteristics, and risk assessment of microplastics and polycyclic aromatic hydrocarbons associated with microplastics in surface water and sediments of the Konya Closed Basin, Turkey.

The presence of polycyclic hydrocarbons (PAHs) and microplastics (MPs) in aquatic environments affects the ecosystems and threatens human health. In this study, the abundance, composition, and morphological characteristics of MPs were determined for the first time in the inland freshwater resources of the Konya Closed Basin, Turkey. The abundance of MPs ranged from 1139 to 23,444 particles/m3 and 150 to 3510 particles/kg in the surface water and sediment, respectively. Fragments and fibers were the most abundant MP shapes in the surface waters (51%, 34%) and sediments (29%, 40%), followed by films, pellets, and foams. Transparent and white MPs were present at the highest percentage in surface waters (72%) and sediments (69%), followed by blue, grey, black, brown, and green. In addition, polyethylene, polypropylene, and cellophane were identified as the main polymers in surface waters (34%, 25%, 24%) and sediments (37%, 17%, 31%). In the Konya Closed Basin, 35% of the surface water samples and 54% of the sediment samples were exposed to very high contamination (CF ≥ 6). Surface waters (PLI: 2.51) and sediments (PLI: 1.67) in the basin were contaminated (PLI > 1) with MPs. The 16 PAHs sorbed on MPs in the surface water and sediment ranged from 394 to 24,754ng/g and from 37 to 18,323ng/g, respectively. Phenanthrene and fluoranthene were the most abundant PAHs sorbed on MPs in all surface waters and sediments. Two to three-ring PAH compounds sorbed on MPs were also dominantly detected in surface waters and sediments, accounting for 68% and 78% of the total 16 PAHs, respectively. The source of PAHs carried by MPs in the Konya Closed Basin was mainly of petrogenic origin. Incremental lifetime cancer risk (ILCR) results indicated that the maximum ILCR values were higher than the EPA acceptable level (10-6) for child (2.95 × 10-5) and adult (1.46 × 10-4), indicating a potential cancer risk.

Spatial distribution of PAHs, nickel, and vanadium in sediments from a large coastal lagoon near a petroleum extraction area in the southern Gulf of Mexico

One of the world's crucial areas for crude oil exploration and extraction is the southern Gulf of Mexico, where Terminos Lagoon (TL) is located. Sediments from the TL region were used to assess the spatial patterns, origins, and ecotoxicological risks associated with 16 priority polycyclic aromatic hydrocarbons (PAHs; 3.1–248.9 ng⸳g−1 dry weight basis, dw) and trace metals (Ni = 11.0–104.0 mg⸳kg−1; V = 2.0–35.0 mg⸳kg−1 dw) linked to anthropogenic activities. Although origin indices based on PAHs and metals concentrations indicate no crude oil pollution in the region, sources of pyrogenic PAHs were identified. A chemometric approach demonstrated associations between organic matter and PAHs, and that metal accumulation depends mostly by the input of lithogenic materials. Ecotoxicological risk estimations showed a higher risk of possible adverse effects in sites near swamps and mangrove zones, highlighting the need of future monitoring. This study provides a reference for policymakers to conserve Mexico's largest coastal lagoon and other oil-impacted coastal areas worldwide.

Semi-diurnal distribution of polycyclic aromatic hydrocarbons bound to PM2.5 and PM0.1 during pollution episode in the urban area of Hanoi.

Every year, Hanoi suffers from several episodes (periods with daily concentration of PM2.5 higher than 50µgm-3 during at least two consecutive days). These episodes are of health concern because of the high concentration of PM2.5 and/or PM0.1 and the presence of PM-bound toxic components, such as, PAHs. In this study, the concentrations of PAHs bound to PM2.5 and PM0.1 in night-time and day-time samples during episode and non-episode periods in December 2021 were determined. The concentrations of PAHs bound to PM2.5 were found to increase significantly from day-time samples of 3.24 ± 0.83ngm-3 to night-time samples of 10.8 ± 4.45ngm-3 in episode periods. However, PAHs bound to PM0.1 increased slightly from day-time samples of 0.58 ± 0.12ngm-3 to night-time samples of 0.89 ± 0.30ngm-3 in episode periods. Diagnostic ratios of PAHs indicate that biomass/coal combustion andvehicular emissionare the primary sources of PAHs. The incremental lifetime cancer risk was estimated to vary from 8.7E-09 to 2.5E-08 for children and 6.7E-08 to 2.2E-07 for adults, respectively. Accordingly, loss of life expectancy was estimated at 0.11min and 0.82min for children and adults, respectively. These findings imply that the carcinogenic impact induced by PAHs via inhalation is negligible during the episode period.

Concentration and Distribution of Specific Siloxanes (D5 and D6) and PAHs in the Anacostia and Potomac Rivers, USA

The waterways adjacent to Washington DC, USA have a history of contamination from heavy metals, nutrients, pesticides, and industrial chemicals. Among the chemicals of concern are PAHs, which are a historical contaminant but also have modern pyrogenic and petrogenic sources in the area’s waterways. Another group of contaminants that are of emerging interest are siloxanes (silicones), which are widely used as lubricants, sealants, and cosmetics. Some lower-molecular-weight siloxanes are regulated by the EU in recognition of harm to aquatic life, but there are no restrictions in the United States. In fact, studies examining water pollutants do not typically test for siloxanes. Here, we present the concentrations of specific PAHs and siloxanes from surface sediments in the Potomac and Anacostia Rivers (including the Anacostia’s tributaries) collected between 2018 and 2023. Both D5 (decamethylcyclopentasiloxane) and D6 (dodecamethylcyclohexasiloxane) were found in most locations, with concentrations averaging 0.13 and 0.006 mg/g (dry mass), respectively. Pyrene, fluoranthene, bibenzyl, and phenanthrene were also found in the Anacostia and some of its tributaries, with concentrations increasing downstream. In the Potomac, concentrations were generally lower than those observed in the Anacostia. Based on ratios of pyrene to fluoranthene + pyrene, the likely source of PAHs was petrogenic.

Risk assessment of PAHs in dusts from surfaces of abandoned automobiles at auto-workshops of three semi-urban areas of Eastern Nigeria: Compositional patterns and source apportionments

The concentrations, sources, compositional patterns, and risk assessments of PAHs in dust on abandoned automobiles at auto-workshops in three semi urban areas were studied. Dust samples were randomly collected from at least five car surfaces in automobile workshops located at Rumuodomaya-Ogale, Ekwulobia, and Awka between December 2019 and March 2020, and analysed for PAHs using the Buck M910 Gas Chromatography-Flame Ionization Detector. Car surface dust from Rumuodomaya-Ogale showed the highest PAH concentration of 2.348 µg/g in March 2020, while that of Awka had the lowest total PAH concentration of 0.129 µg/g in February 2020. Dust from the Ekwulobia consisted mostly of 3-ring PAHs throughout the month, except in January 2020. Rumuodomaya-Ogale dust had high BaPTEQ values, indicating a potential carcinogenic risk for automobile workers. Considerable cancer risk may arise from prolonged exposure of adult’s automobile workers to PAHs in dust via dermal contact and inhalation. The ingestion cancer risk values for children were higher than adult counterparts (except in Awka, December 2019). The principal component analysis suggested the influence of exhaust emissions on the source of PAHs in dusts of automobile workshops. There is a need for automobile workers to have and wear personal protection equipment (PPE) while on duty to reduce the risk associated with exposure to PAHs in dust particles.

Capturing pollution characteristics in different air mass experimentally using an automatically directional air sampler

Pollution characteristics in air masses from different directions could be dissimilar and consequently have distinct impacts on human health; however, available studies did not provide separated results of pollution characteristics for air from different directions in one experiment when using traditional air samplers. Here, an Automatically Directional Air Sampler (ADAS) is developed and evaluated aiming at providing a new sampling approach for capturing and comparing hazardous air pollutants in different air masses. PM2.5 and particulate polycyclic aromatic hydrocarbons (PAHs, including 16 priority and 13 non-priority ones) are measured as targeted air pollutants in evaluating the performance of this new device. The time-weighted averages of pollution levels over the whole sampling duration using the ADAS were close to that using a traditional air sampler, but the former clearly captured distinct pollution characteristics such as pollution levels, composition profiles and potential sources of PAHs in air masses from different directions. The new device also provided an estimate of relative contributions of air pollution in different air trajectories. In the study site, air mass from the west had relatively high pollution levels, at 6.83 ng/m3, but contributed to only 14% of the averaged 0.75 ng/m3 during the sampling period. Sampling absorbents or channels can be modified in future to collect other air pollutants of interest. The experimental evidences of different pollution characteristics in different trajectories are important in identifying priority risk sources and developing pollution control strategies more efficiently.

PAH levels in sediments from a coastal area heavily subjected to anthropogenic pressure (Asturias, north of Spain)

Ninety-two sediment samples collected along the Asturias coastline (north of Spain), were studied based on their concentrations of 16PAHs. Concentrations of Σ16PAH showed an average of 12.650 mg kg−1 d.w., which is higher than most other studies conducted around the world. The origins of PAHs present in the sediments are mainly from fuel combustion in industrial processes. The main source of PAH to the coastal system seems to be the Nalón River, which played a significant past role related to different industrial activities, highlighting thermal power stations located in the basin. On the other hand, the Avilés Estuary, hotspot of the regional heavy metallurgical industry was the area with the highest concentrations of Σ16PAH, with an average of 5 to 6 times higher than the rest studied. The risk assessment of Σ16PAH concentrations in the study area showed a high potential risk of contamination transfer to other environmental compartments.

Source-specific ecological and health risks of polycyclic aromatic hydrocarbons in the adjacent coastal area of the Yellow River Estuary, China.

Industrialization and urbanization have led to increasing levels of PAH pollution in highly urbanized estuaries and their adjacent coastal areas globally. This study focused on the adjacent coastal area of the Yellow River Estuary (YRE) and collected surface seawater, surface sediment, and clams Ruditapes philippinarum and Mactra veneriformis at four sites (S1 to S4) in May, August, and October 2021 to analyze the source-specific ecological and health risks and bioeffects. The findings revealed that the main sources of PAHs were traffic emission (25.2% to 28.5%), petroleum sources (23.3% to 29.5%), coal combustion (24.7% to 27.5%), and biomass combustion (19.8% to 20.7%). Further, the PMF-RQ and PMF-ILCR analyses indicated that traffic emission was the primary contributor to ecological risks in seawater and health risks in both clam species, while coal combustion was the major contributor in sediment. Taken together, it is recommended to implement control strategies for PAH pollution following the priority order: traffic > coal > petroleum > biomass, to reduce the content and risk of PAHs in the YRE.

Evaluation of Sources of Polycyclic Aromatic Hydrocarbons in Thermally Treated Meat and Fish: A Food Pollutant Study

This study assessed the sources of PAH in cooked meat and fish. Gas Chromatography-Mass Spectrometry (GC-MS) performed the sample analysis. The total PAH concentrations (mg/kg) ranged from 0.911 to 2.763. Levels of low-molecular-weight (LMW) PAHs varied from 0.353 mg/kg to 1.786 mg/kg, while high-molecular-weight (HMW) PAHs ranged from 0.516 to 0.977 mg/kg. The study detected 2 to 6-ring PAHs, the 3-ring PAHs were the most prominent. PAHs diagnostic ratios, their plots and principal component analysis (PCA) were used to assess the origin of PAHs in the samples. Values of diagnostic ratios, such as Phenanthrene/Anthracene (1.84–3.58), Anthracene/(Anthracene + Phenanthrene) (0.21–0.35), Fluoranthene/Pyrene (0.00-1.79), Fluoranthene /(Fluoranthene + Pyrene) (0.00-0.64), Indeno[123-cd-]pyrene/(Indeno[123-cd-]pyrene + Benzo[ghi]perylene) (0.00–43), LMW-PAH/HMW-PAH (0.59–1.83) and Benzo[a]pyrene/(Benzo[a]pyrene + Chrysene) (0.00–0.50) indicated that the PAHs in the samples were from mixed sources, with greater contributions from pyrogenic sources. They show that the barbecued samples were contaminated primarily by pyrogenic PAHs (biomass (wood/charcoal) burning, liquid fuel combustion, or automobile exhaust emissions). The grilled and smoked samples were mostly contaminated from different combustion sources (traffic and non-traffic, biomass burning, automobile exhaust and liquid fuel), with little input from petrogenic sources. The combination plots of the ratios also show that PAH was from mixed sources (petrogenic and pyrogenic), but mostly from a pyrogenic source (wood/charcoal burning, liquid fuel combustion, and automobile exhaust emissions) with minor inputs from petrogenic origin, as shown by the value of LMW-PAH/HMW-PAH ratios > 1 in a few samples. PCA equally showed that four factors accounted for 82.47% of the total variability and separated the PAHs into identifiable source groups, comprising mixed sources, combustion of liquid fossil fuel, automobile/diesel engine exhaust, gasoline and oil combustion and biomass burning. The study showed that contamination from the natural habitats of the animals contributed to the PAHs in them in addition to the cooking process. This therefore underscored the impacts of anthropogenic pyrogenic activities on PAHs formation and levels in meat and fish, hence adequate control/reduction of these activities will promote a healthier and safer food environment for all.

The occurrence and sources of PAHs, oxygenated PAHs (OPAHs), and nitrated PAHs (NPAHs) in soil and vegetation from the Antarctic, Arctic, and Tibetan Plateau

Although the fate of PAHs in the three polar regions (Antarctic, Arctic, and Tibetan Plateau) has been investigated, the occurrence and contamination profiles of PAH derivatives such as oxygenated PAHs (OPAHs) and nitrated PAHs (NPAHs) remain unclear. Some of them are more toxic and can be transformed from PAHs in environment. This study explored and compared the concentrations composition profiles and potential sources of PAHs, OPAHs, and NPAHs in soil and vegetation samples from the three polar regions. The total PAH, OPAH, and NPAH concentrations were 3.55–519, n.d.–101, and n.d.–1.10 ng/g dry weight (dw), respectively. The compounds were dominated by three-ring PAHs, and the most abundant individual PAH and OPAH were phenanthrene (PHE) and 9-fluorenone (9-FO), respectively. The sources of PAHs and their derivatives were qualitatively analyzed by the diagnostic ratios and quantified using the positive matrix factorization (PMF) model. The ratios of PAH derivatives to parent PAHs (9-FO/fluorene and 9,10-anthraquinone/anthracene) were significantly higher in the Antarctic samples than in the Arctic and TP samples, implying a higher occurrence of secondary OPAH and NPAH formation in the Antarctic region. To our knowledge, this is the first comparative study that simultaneously investigated the contamination profiles of PAHs and their derivatives in the three polar regions. The findings of this study provide a scientific basis for the development of risk assessment and pollution control strategies in these fragile regions.

Sources and influences of atmospheric nonpolar organic compounds in Nanchang, central China: Full-year monitoring with a focus on winter pollution episodes

Nonpolar organic compounds (NPOCs) are found in atmospheric aerosols and have significant implications for environmental and human health. Although many studies have quantitatively estimated the sources of NPOCs in different cities, few have evaluated their main influencing factors (e.g., emissions and meteorological conditions) at relatively long (e.g., different seasons) and short timescales (e.g., several days during pollution episodes). A better understanding of this issue could optimise strategies for dealing with organic contamination in atmospheric particulate matter. NPOCs (including n-alkanes, PAHs and hopanes) in fine particulate matter (PM2.5) were sampled daily at Nanchang, China, from 1 November 2020 to 31 October 2021. Analyses of specific biomarkers and diagnostic ratios indicate that the NPOCs mainly had anthropogenic sources. The quantitative estimates of a positive matrix factorization model show that fossil fuel and biomass combustion were the main sources of n-alkanes (contributing 64.8 %), while vehicle exhaust was the main source of PAHs (47.0 %) and hopanes (52.3 %). Seasonally, the contributions from coal and/or biomass combustion were higher in autumn and winter (40.2–56.3 %) than in spring and summer (25.7–44.3 %), while contributions from natural plants, petroleum volatilization and vehicle exhaust were higher in spring and summer (14.7–63.5 %) than in autumn and winter (8.1–48.9 %). Redundancy analysis shows that increased emissions, especially from coal and/or biomass combustion, are the main cause of increases in NPOCs, during both annual sampling periods and winter pollution episodes. Over the year, higher temperature and longer sunshine hours correspond to lower NPOC concentrations. In winter pollution episodes, increases in temperature and relative humidity correspond to increases in NPOC concentrations. Our results suggest that controlling primary emissions, especially from coal and biomass combustion, may be an effective way to prevent increases in NPOC concentrations.

Assessment of single- and dual-PUF-containing passive air samplers for the collection of atmospheric PAHs

In this study, atmospheric polycyclic aromatic hydrocarbons (PAHs) were determined in fifteen individual, consecutive sampling events conducted in a semi-urban area of Bursa between June 2021 and February 2022 using passive air samplers (PASs). In this study, PASs containing single and dual PUF disks were used simultaneously and side by side. The aim of this study was to compare the results obtained from PASs containing single and dual PUF disks in terms of mass and number of PAH compounds. To our knowledge, the use of PASs containing dual PUF disks was applied for the first time in the literature. Because of the extended surface area, dual PUFs containing PAS can sample and detect more atmospheric PAHs. PAH masses in both samplers had a decreasing relationship with temperature. During the sampling period, the total masses of PAHs (∑16 PAH) were calculated as 1058 ± 1042 ng (117–3380 ng) on single-PUF disks and 1930 ± 1749 ng (279–5640 ng) on dual-PUF disks. The ratio of the dual-PUF value to the single-PUF value for ∑16 PAH in the samples varied between 1.41 and 3.45 (1.99 ± 0.50). Moreover, when the single and dual PUF mass results were evaluated on a compound basis, high correlation results were obtained. The sampling characteristics of both samplers were interpreted with the effect of possible PAH sources. It was determined that both samplers were affected by the same sources in the region due to the high similarities in diagnostic ratios. The main sources of PAHs were primarily residential heating and vehicle emissions.

Characterization and Source Apportionment of Polycyclic Aromatic Hydrocarbons in PM2.5 in Lanzhou

To study the pollution characteristics and sources of 16 PAHs in PM2.5 in Lanzhou, PM2.5 samples were collected in four seasons. GC-MS was employed to analyze the concentration of PAHs. Positive matrix factorization(PMF), trajectory cluster, and potential source contribution function(PSCF) were used to identify the sources of PAHs. The results indicated that the average concentration of PAHs in PM2.5 in Lanzhou decreased in the order of winter[(118±16.2) ng·m-3]>autumn[(50.8±21.6) ng·m-3]>spring[(22.2±8.87) ng·m-3]>summer[(4.65±1.32) ng·m-3]. The results of correlation analysis showed that PM2.5 and TPAHs in Lanzhou had an extremely significant negative correlation with temperature; an extremely significant positive correlation with atmospheric pressure; and a poor correlation with wind direction, wind speed, and relative humidity. The proportion of PAHs with 4-5 rings was much higher than that of those with 6 rings and 2-3 rings, with similar results across the four seasons. Source apportionment results illustrated that the contribution of industrial emissions and biomass and natural gas combustion were dominant in spring and summer seasons. Industrial emissions and coal combustion were dominant in autumn and winter, respectively. The vehicle emissions had no significant change across the four seasons. Trajectory cluster and PSCF analyses showed that the airflow coming from Mongolia, northeast Xinjiang, and Qinghai had important effects on the ambient air quality in Lanzhou.

Analysis of PAHs content, source and risk assessment in surface sediments from Laizhou Bay and Bohai Bay

To understand the levels of PAHs and ecological risks to the marine environment in Laizhou Bay and Bohai Bay, 33 sediment samples were collected in the region for analysis. PAH concentrations ranged from 98.22 ng·g−1 (dw) to 239.01 ng·g−1 (dw). PAHs in the region are at low to medium pollution levels compared to studies worldwide. Diagnostic ratios and PCA indicate that PAHs are primarily sourced from fuel combustion. PAHs carried into the Bohai Sea by means of river water and sediment are more likely to settle to the seafloor as opposed to diffuse. This results in a slightly higher proportion of low-ring PAHs than high-ring PAHs. Low-ring PAHs accounted for 56 % of the total. Low-ring PAHs are key contributors to ecosystem risk. The SQGs and RQ∑PAHs show that PAHs do not pose a considerable ecological danger within the region.

Source characteristics of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in surface soils of Shenyang, China: A comparison of two receptor models combined with Monte Carlo simulation

The surface soil concentrations of 16 PAHs and 15 PCBs were simultaneously determined by gas chromatography-tandem mass spectrometry in 21 locations of urban areas of Shenyang. The average concentrations of PAHs and PCBs were 26.40 ± 34.68 mg/kg and 48.03 ± 27.47 μg/kg, respectively. Factor analysis with nonnegative constraints (FA-NNC) and absolute principal component score with multiple linear regression (APCS-MLR) model were used to explore and evaluate the sources of PAHs and PCBs in the study area. The results of FA-NNC showed that PAHs in soils were mainly from traffic emissions (49.64%), coal combustion (46.88%) and petrogenic source (3.49%). The PCBs in soils were mainly from commercial and high temperature combustion mixed sources (20.3%), combustion and industry emission mixed sources (21.1%), electrical equipment sources (22.2%) and traffic emission sources (36.4%). The results of APCS-MLR were consistent with those of FA-NNC. The uncertainty of FA-NNC and APCS-MLR model was analyzed by Monte Carlo simulation method. The results revealed the reliability of the two receptor models on source apportionment. The estimated carcinogenic risks indicated that the risks of PAHs in soils exceed the acceptable range (10−6-10−4), while the risks of PCBs were below the acceptable risk level of 10−6.

Linking PAHs concentration, risk to PAHs source shift in soil and water in epikarst spring systems, Southwest China

A systematic assessment of the variations in the ecological risk of PAHs and the key emission sources controlling the variations is of great importance to human health and aquatic organisms. PAH concentrations, composition, source, and ecological risk in soils and water in two different periods (2010–2011 and 2019) of three typical epikarst springs in Southwest China were investigated. Results showed that PAH concentrations in soil and water have an overall downward trend (a reduction of 57 % and 93 %, respectively) in the past 10 years, which is consistent with the downward trend in the relative contribution rate of raw coal production (a 66 % reduction). In terms of composition, the proportion of low-ring PAHs decreased, medium-ring and high-ring PAHs increased in the soil profile. The proportion of low-ring PAHs did not change obviously, the proportion of medium-ring PAHs increased, and the proportion of high-ring PAHs decreased in epikarst springs. The source of PAHs changed remarkably over time, the relative contribution of coal combustion to PAHs decreased from 38 % to 20 %, and the vehicle contribution of PAHs increased from 31 % to 44 % in soils. The relative contribution rate of unburned oil and coke oven and biomass combustion change is less. Furthermore, the ecological risk of PAHs in the soils was reduced from moderate risk 2 to moderate risk 1, the risk in epikarst spring was reduced from high risk to moderate risk 2 after 10 years. This study demonstrates that substituting petroleum and coal with green energies can reduce PAH concentrations and risk.

Pollution patterns and their effects on biota within lotic and lentic freshwater ecosystems: How well contamination and response indicators correspond?

Aquatic environments are often severely polluted with chemical substances of anthropogenic origin, which can pose a potential threat to aquatic organisms and human health. In this study, patterns and sources of heavy metals (HMs, 6 metals) and polycyclic aromatic hydrocarbons (PAHs, 16 hydrocarbons), contamination indicators, environmental genotoxicity measures and metrics of ecological status in lotic and lentic ecosystems were collated for the first time. Chemical analysis has confirmed previously reported long-term contamination at certain study sites. The sediments of Lake Talkša, located in a city and characterized by exclusive anthropogenic pressure, exhibited the highest levels of contamination by both HMs and PAHs. Through positive matrix factorization (PMF) analysis, vehicle and industrial emissions were identified as the primary sources of HMs and PAHs. Our results revealed that frequencies of genotoxic aberrations were higher in river sites compared to lakes, with the highest genotoxic risk observed in the Nemunas River below industrial cities Alytus and Kaunas. Surprisingly, even the severely contaminated Lake Talkša showed only a "moderate" grade of genotoxic risk, highlighting the potential for adaptation of biota to long-term contamination especially in lentic ecosystems. The ecological quality status assessed by macroinvertebrate metrics, which may be sensitive to observed high biological contamination, appeared to be unrelated to contamination patterns. Consequently, to obtain the robust information on anthropogenic contamination and its effects, a combination of various assessment methods and metrics should be employed.

Urbanization affects the composition, source, and risk of soil PAHs in lakeside residential area of the Yangtze River Delta, China

Urbanization affects the composition, source, and risk of soil PAHs in lakeside residential area of the Yangtze River Delta, China