PAH Concentrations Research Articles

Source Apportionment of Polycyclic Aromatic Hydrocarbons in Indoor Fine Dusts from Residential and Public Buildings in Port Harcourt, Rivers State, Nigeria

The sources of polycyclic aromatic hydrocarbons in indoor fine dust from residential and public buildings in Port Harcourt, Rivers State, Nigeria was investigated using source apportionment tools such as diagnostic/isomeric ratios, principal component analysis (PCA) and hierarchical cluster analysis (HCA). A total of twenty-seven indoor fine dusts comprising of twenty samples from residential building and seven samples from public buildings were collected from Port Harcourt. The PAHs in the dust samples were quantified by gas chromatograph equipped with mass spectrometry (GC-MS) after extraction by ultra-sonication with hexane/dichloromethane/acetone and cleaned up on a silica gel/alumina column. The Σ16 PAH concentrations in the indoor fine dusts ranged from 3136 µg kg-1 to 44332 µg kg-1 for residential buildings and 2580 µg kg-1 to 15372 µg kg-1 for public buildings. The results of source apportionment indicated that the PAHs in the indoor fine dusts were from mixed sources pyrogenic sources (coal, wood, petroleum, biomass, and fossil fuel combustion) and petrogenic sources with significant contribution from pyrogenic sources.

Bioaccumulation of PAHs in marine bivalves of the Santos Estuary (Brazil) associated with the evaluation of human consumption

The present study aimed to evaluate concentrations of 16 priority PAHs in the mussel Perna perna and oyster Crassostrea rhizophorae of the Santos Estuary (Brazil) and the potential risk to human health associated with the consumption of these species. The levels of ΣPAHs in the tissues of bivalves ranged from 96.94 to 988.76 μg/kg for mussels and from 88.38 to 138.62 μg/kg for oysters. A general trend of higher concentrations of PAHs was observed according to the increase in log Kow values in both species. The estimated amount of ΣPAHs via mussel and oyster intake ranged from 1.0 to 3.2 ng/kg and from 0.4 to 1.2 ng/kg of body weight per day, respectively. The calculated THQs, HI and CRs for the regular consumption of raw bivalves followed the internationally acceptable limits and represent a low risk to human health.

Effect of biochar chemical modification (acid, base and hydrogen peroxide) on contaminants content depending on feedstock and pyrolysis conditions

The effect of biochars (BCs) chemical modifications on the content of various contaminants is poorly studied and understood, despite the fact that such results would be important in terms of estimating the safety of BCs application. The aim of this study was to evaluate the content of different types of contaminants - heavy metals (HMs), polycyclic aromatic hydrocarbons (solvent extractable - Ctot and freely dissolved - Cfree PAHs) and environmentally persistent free radicals (EPFRs) in post-pyrolytic chemically modified (HNO3, KOH and H2O2) BCs produced under diverse conditions (temperature and carrier gas) and from various feedstocks (willow, rice husk, sewage sludge, oil seed rape straw, wheat straw). The physio-chemical properties of BCs were determined (such as morphology, elemental composition and chemical state, and crystalline structure) and correlated with contaminants content. Regardless of the BCs type, acid modification reduced HMs and Ctot PAHs the most effectively but simultaneously increased Cfree PAHs and EPFRs content (compared to pristine BCs). Changes in contaminant content after H2O2 and alkali treatment were more varied and strictly related to the physio-chemical properties of BCs (such as porosity, DOC, and polarity). H2O2 treatment reduced Ctot and Cfree PAHs content but was less effective than acid modification. In contrast, KOH treatment significantly increased the Ctot in most BCs, which depends mainly on porosity and DOC changes. Also, the reduction in HMs content and increase in EPFR after alkali and H2O2 treatment were less substantial and more differentiated by BC origin than after acid modification.

The Cytotoxic Effects of Fine Particulate Matter (PM2.5) from Different Sources at the Air-Liquid Interface Exposure on A549 Cells.

The health of humans has been negatively impacted by PM2.5 exposure, but the chemical composition and toxicity of PM2.5 might vary depending on its source. To investigate the toxic effects of particulate matter from different sources on lung epithelial cells (A549), PM2.5 samples were collected from residential, industrial, and transportation areas in Nanjing, China. The chemical composition of PM2.5 was analyzed, and toxicological experiments were conducted. The A549 cells were exposed using an air-liquid interface (ALI) exposure system, and the cytotoxic indicators of the cells were detected. The research results indicated that acute exposure to different sources of particulate matter at the air-liquid interface caused damage to the cells, induced the production of ROS, caused apoptosis, inflammatory damage, and DNA damage, with a dose-effect relationship. The content of heavy metals and PAHs in PM2.5 from the traffic source was relatively high, and the toxic effect of the traffic-source samples on the cells was higher than that of the industrial- and residential-source samples. The cytotoxicity of particulate matter was mostly associated with water-soluble ions, carbon components, heavy metals, PAHs, and endotoxin, based on the analysis of the Pearson correlation. Oxidative stress played an important role in PM2.5-induced biological toxicity.

Variation in urban snow quality indicated by three seasonal sampling surveys conducted in Luleå (Sweden) within a span of 27 years

Concentrations of total suspended solids (TSS), trace metals (Cu, Cd, Cr, Zn, Cd, Pb), Na and 16 US EPA priority PAHs in urban snow were studied in the City of Luleå in Northern Sweden. Snow was sampled at six central urban and suburban sites with various traffic intensities, in three sampling surveys (1994–95, 2002–03, 2020–21), repeated for three ages of the urban snow cover of 40, 80, and 120 days, respectively. The older data, from the 1994–95 and 2002–03 surveys, were obtained from the existing literature. The concentrations and mass loads of TSS and most trace metals studied (Zn, Cu, Pb, and Cd) varied with time. TSS, Zn, and Cu showed slightly higher concentrations and mass loads in the 2003 (TSS avg = 2300 μg/L, Zn avg = 620 μg/L and Cu avg = 250 μg/L) and 2021 (TSS avg = 1500 μg/L, Zn avg = 530 μg/L and Cu avg = 220 μg/L) sampling surveys, compared to the 1995 survey (TSS avg = 620 μg/L, Zn avg = 240 μg/L and Cu avg = 97 μg/L). However, no evident trend was observed between the 2003 and 2021 sampling surveys. The highest concentrations of Pb and Cd were observed in snow samples from the 1994–95 sampling survey (Pb max = 570 μg/L, Cd max = 4.6 μg/L). Results indicated higher concentrations of the pollutants studied in the city centre, compared to the residential suburbs, and in areas with heavier traffic, where concentrations of metals correlated well with traffic intensity. Fractionation analysis of trace metals indicated that Zn, Cu and Pb occurred mostly in the particulate-bound phase (>0.45 μm) containing the most of Zn, Cu, and Pb mass, at 80, 84 and 94% of the total, respectively. Over 50% of the dissolved phase of Zn and Cu was in the truly dissolved fraction (<3000 MWCO). Concentrations of PAHs also increased with traffic intensity, with pyrene being the most frequently detected PAH, likely because of the strength of sources and various physical processes influencing the snowbanks development and causing spatial and temporal variations in pollutant concentrations.

Characterisation of flavourous sesame oil obtained from microwaved sesame seed by subcritical propane extraction

This study developed a novel and green method to produce fragrant sesame oil using microwaves and subcritical extraction (SBE). Sesame seeds were microwaved at 540 W for 0–9 min before subcritical propane extraction at 40 °C and 0.5 MPa. SBE caused less deformation to the cellular microstructure of sesame cotyledons while dramatically improving oil yield (96.7–97.1 %) compared to screw processing (SP) (53.1–58.6 %). SBE improved extraction rates for γ-tocopherol (381.1–454.9 μg/g) and sesame lignans (917.9–970.4 mg/100 g) in sesame oil compared to SP (360.1–443.8 μg/g and 872.8–916.8 mg/100 g, respectively). Microwaves generated aroma-active heterocyclics and phenolics faster than hot-air roasting in sesame oil with a better sensory profile. SBE had a higher extraction rate for aroma-active terpenes, alcohols, and esters while reducing the concentrations of carcinogenic PAHs and HCAs in sesame oil. The novel combination process of microwaves and subcritical extraction is promising in producing fragrant sesame oil with superior qualities.

Organic contaminants levels, distribution and risk assessment in Jeddah marine coastal zone sediments

Herein, various organic contaminants were determined in surface sediments collected from the Jeddah coastal zone, Saudi Arabia, to assess their levels, origin and probable toxic effects on marine organisms. High hydrocarbons concentrations, indicative of an enhanced pollutant burden, were recorded in the Jeddah Lagoon (mean value 4100 mg/kg for total aliphatic hydrocarbons (∑AHC) and 5800 μg/kg for total polycyclic aromatic hydrocarbons (∑PAH)), whereas mean values in Mena Jeddah were 258 mg/kg for ∑AHC and 615 μg/kg for ∑PAH. By using molecular diagnostic ratios/indices and applying Positive Matrix Factorization, petroleum related pollution seems to predominate in Jeddah lagoons, whereas carcinogenic contaminants of pyrolytic origin were dominant in Mena Jedda. Additionally, municipal wastewaters were identified as a major source of pollution in Jeddah lagoons. Comparison of the concentrations of individual PAHs and polychlorinated biphenyls with sediment quality guidelines indicates that, despite their high total values, adverse biological effects are unlikely to occur.

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.

Dietary Exposure to Polycyclic Aromatic Hydrocarbons and the Probabilistic Health Risk Assessment of Eating Roasted Yams (Dioscorea Species) by African Population

The roasting of food is one of the oldest food preparation and preservation technologies. Although roasted foods have been associated with potential health hazards, this processing method is still used in many foods. This study was carried out to ascertain the health risks of ingesting white (Dioscorea rotundata), and bitter yam (Dioscorea dumetorum) roasted with firewood, charcoal, and charcoal augmented with PET bottles. The PAH content in all the roasted yam samples was identified and analyzed using gas chromatography-mass spectroscopy (GC-MS). A total of 8 PAHs were identified in both yam species; however, bitter yam roasted with augmented charcoal contained 9 PAHs. The total EDI showed that bitter yam roasted with augmented charcoal (6.59E-1) had the highest PAH content while white yam roasted with only charcoal contained the lowest (1.27E-1). The hazard quotients and indexes revealed that bitter yam had the highest HQ in all the roasting methods except for napathalene, fluoranthene and benzo (a) pyrene in samples roasted with charcoal. The HI for both species in all the roasting methods was above 1 (&gt;1), while firewood produced the highest HI. Benzo (a) anthracene was the most potent PAH identified across the yam species and the roasting techniques. The evaluated ILCR showed that dibenzo (a, h) anthracene identified in white yam smoked with charcoal had the highest tendency to cause cancer (6.38E-1) while the least PAH was acenaphthylene (3.35E-6) which was seen in bitter yam roasted with charcoal. Therefore, it is necessary to inform the consumers of the possible health implications associated with consuming roasted yams and especially yam roasted with augmented charcoal

Effect of gas additives on soot formation in flat laminar premixed ethylene/air flames under low pressure

This study reports on the effect of the additive gases, namely N2, CO2, and Ar, on the soot formation in laminar premixed C2H4/air flames at low pressure of 40 kPa. The flames blended with N2, CO2, or Ar were experimentally investigated, where the emission spectra of CH* and C2*, qualitative concentration of PAHs, and soot volume fraction (fv) were measured using laser and optical diagnostic methods. The flame temperature was measured using a thermocouple. The results reveal that additive gases significantly influence flame height above the burner and fuel combustion as well as reduce soot formation and flame temperature. With respect to N2 and CO2, Ar proves the most effective in reducing soot volume fraction, achieving a 100-fold reduction compared to the reference flame. Moreover, the additive gases were found to delay the ignition, leading to a 5 mm downstream shift in soot inception. Despite the difference in the properties of the three gas additives, it was found the first incepted soot particles were detected at a common temperature, Tinception, of 1515 ± 70 K. Three regimes related to the soot appearance rate were identified, which are the fast-increasing range from the soot inception location, the plateau region, and the decreasing range to the flame front of 20 mm. According to the Lagrangian time-derivative of soot volume fraction (dfv/dt) as a function of fv, the constant of surface growth (kSG) was determined to be 170 s−1 in the flame with additives of CO2 and Ar, measured at 40 kPa. The identified turning point between the plateau region and the negative soot increase regions can be used as an indicator of the transition from higher to lower soot formation rates in soot modeling.

Profile distribution of polycyclic aromatic hydrocarbons in coastal soils of the Lower Don and Taganrog Bay, Russia

The main regularities of pollutant distribution through the soil profile were established based on the analysis of the content of 15 priority PAHs in 29 soil sections of different soil types located in the coastal zone of the Lower Don and Taganrog Bay with different anthropogenic loads. It was shown that the total content of PAHs in the 0-20 cm layer of soils of coastal territories varies from 172 µg kg-1 to 16006 µg kg-1. In addition, according to the total pollution indicator, (Zc) determines the level of soil pollution, which varies from "not polluted" to "extremely polluted". The influence of pollution sources falls on the 0-20 cm layer of soils of different types and is especially pronounced for subordinate landscapes. With increasing sampling depth, the total PAH content decreases with the redistribution of individual compounds of the PAH group towards the dominance of low molecular weight and 4-ring compounds in the composition of the sum of 15 PAHs and depends largely on the content of organic matter and soil pH. Based on the cluster analysis results, the main factor determining the profile distribution of PAHs is the type of pollutant origin source and its intensity.

Effects of anthropogenic and environmental stressors on the current status of red mullet (Mullus barbatus L., 1758) populations inhabiting the Bulgarian Black Sea waters

The red mullet (Mullus barbatus Linnaeus, 1758) is a keynote species for the Bulgarian Black Sea ecosystem and fisheries; nevertheless, existing knowledge on population status is very scarce. The present study was intended to assess the health status and adaptive potential of M. barbatus populations inhabiting the Bulgarian waters of the Black Sea. Our findings revealed that populations of M. barbatus are exposed to a variety of anthropogenic and environmental stressors. The species’ status was assessed using representative genetic, morphological, biochemical and chemical biomarkers from specimens obtained in the research area’s northern and southern regions. Based on mtDNA markers, genetic analysis revealed low haplotype and nucleotide diversity, typically observed in overexploited or “threatened” populations. Examining the morphology of the specimens revealed no discernible pattern of differentiation. Except for aluminium and chrome, metal and PAH concentrations in fish were below the regulatory thresholds. The specimens from the southern region ingested more microplastics than those from the northern region. The majority of specimens collected from the southern region also exhibited elevated levels of oxidative stress and decreased antioxidant defence, which can be interpreted as an early indication that they had reached the limits of their adaptive potential. Further research on the composite effects of the stressogenic environment on the Black Sea biota are critically needed, as well as the introduction of new indicators and thresholds at molecular and cellular levels for adequate monitoring of both the ecological state of the marine environment and its biota.

Features of Seasonal Changes in PAH Concentration in the Bottom Sediments of Southern Baikal in the Town of Baikal’sk Area

Features of Seasonal Changes in PAH Concentration in the Bottom Sediments of Southern Baikal in the Town of Baikal’sk Area

Impact Assessment of Petrol Filling Stations on Groundwater Quality in Akure Metropolis, Ondo State

Abstract: The presence of PFSs in urban areas has increased significantly, leading to conflicts with existing land use planning and violations of the minimum environmental safety requirements set by the Department of Petroleum Resources (DPR) and have adverse social and environmental impacts despite their socioeconimic importance. This paper aim to investigate the spatial distribution of petrol filling stations and their impact on groundwater quality in Akure Metropolis of Ondo State. A total of 147 PFSs and 140 water wells were identified and recorded. Laboratory analysis was done purposefully on wells near PFSs that were both 26 years or older and still functional, as older underground storage tanks (USTs) pose a potential threat to groundwater safety. Findings revealed 119 functional filling stations, 28% located within residential area and 68% domiciled in commercial areas, 2% in outskirt of town and 1% in standalone environment. Findings showed all mapped filling stations were found to be within 50m from built up (residential) area, 104 mapped stations within residential and commercial areas violates the DPR standard. Using spatial analysis, it was also found that 116 of the 147 (78.9%) mapped filling stations were within 400m away from the next. 108 of the 147 (73.47%) mapped PFSs violated the standard of distance not less than 15meters from the edge of the road to the nearest pump. The findings also showed that groundwater system is contaminated by PAHs, which comprises; naphthalene.F, pyrene and acenaphthylene.F. Low mean concentrations of PAHs recorded in this study suggest that there is no major compromise in the quality of groundwater due to the operation of PFSs in Akure metropolise Hand-dug Wells in the study area. It is recommended that spatial compliance for siting PFSs should be strictly adhered to in order to avoid disaster that may occur due to the hazard they pose

The concentrations of polycyclic aromatic hydrocarbons in fish: A systematic review

This study was conducted on the concentrations of PAHs, including benzo[a]pyrene and the sum of four PAHs (benz[a]anthracene, chryseno, benzo[b]fluoranthene, and benzo[a]pyrene), in unsmoked fish tissues. The values were related to the time period, locality (country and region), living habits, eating habits, and types of environments of the fish species. The data obtained has been also compared with the limits established by the United States Environmental Protection Agency (U.S. EPA) and European Union (E.U.) legislation. The data were collected through a PRISMA systematic review (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) from 1982 to 2020. Only documents that presented the PAHs concentration values were selected. China, Nigeria, and Iran had the highest number of studies. The species Coptodon zillii, Siganus punctatus, and Liza abu were the most commonly used bioindicators. Fish inhabiting demersal and pelagic environments showed the highest concentrations of PAHs. The majority of PAH concentrations of the analyzed documents fell within permissible limits for human consumption, representing a total percentage of 79.49 % for benzo[a]pyrene and 82.86 % for the sum of the 4 PAHs. Although some studies identified concentrations of benzo[a]pyrene alone and benzo[a]pyrene, benz[a]anthracene, chryseno, benzo[b]fluoranthene above the legislation limits, in most of them, the concentrations reported in fish tissue were below the limits defined by European Legislation for human consumption.

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.

Study the Concentration of PAHS in Al-Rumayth River Water-Iraq

This study’s goals were to look into PAH concentrations and compositions as well as chemical and physical water characteristics. In Al –Rumaytha river. This study was conducted out during from November 2021 to October 2022. According to the results, sixteen PAHs compounds were found in the water, including According to the results, water contained sixteen different PAHs components including Acenaphthene and Acenaphthylene ranged between (47.1-91.5, 24.9-55.7) ppm, The values Anthracene, Naphthalene, phenanthene and fluorine results ranged (14.9-48.9 ppm,18.9 -68.7ppm,8.9-41.7 ppm,8.5-41 ppm) respectively, the minimum and maximum concentrations of Benzo[A]anthracen, Benzo[B]fluoranthene, Benzo [K] fluorantyene, Benz [G,H] perylen, Benz [A] Pryene, Chrysene, Dibenzo [A,H] Anthracene, Anthracene, Fluoranthene, Indeno and Pryene was 4.1-20.6 ppm, 20.1-69.7ppm, 30.1-97.4 ppm,4.1-36.9 ppm,0.29-1.6ppm 10.5-40.8 ppm, 8.9-36.9 ppm, 6.5-33.4 ppm,2.5-10.2 ppm,1.3-10.4 ppm. The results show that the Al-Rumaytha River is PAH-polluted, with human activities having the greatest negative effects on the river’s water quality and health.

The Effect of Hydrocarbon Pollution on Niger Delta Root Crops: A Case Study of Cocoyam [Colocasia Esculenta

This paper investigates effects of re-occurring oil spillages on cocoyam, Colocasia esculenta (L.). It studies changes in petiole lengths, leaf blades, chlorophyll concentrations in leaves, and PAH and BTEX concentrations in tubers for three generations under diverse conditions. 8 10-gallon grow bags were used: Grow bags 5–8 were treated with a controlled quantity (4 L/cubic metre) of liquid crude hydrocarbon in the months of June 2019–2021; with 2 replications, after a 2-3-day interval within a week. In grow bags 3, 4, 7, and 8, poultry manure were applied once in 2 months after small seedlings emerged from soil surfaces. Grow bags 1 and 2, 3, and 4 served as “controls” for non-contaminated growth. Grow bags 7 and 8 were treated with hydrocarbons and poultry manure. In the first generation, coco yams planted in grow bags 7-8 showed growth responses (average values of 1.04 m, 51 cm, 4.45 mg/g for petiole length, leaf blade length, and chlorophyll concentration, respectively) very similar to coco yams planted in pristine soil with poultry manure with average values of 1.00 m, 50 cm, 3.45 mg/g. The cocoyams planted in pristine organic rich soils showed similar response with or without fertilizers (average values of 0.98 m, 48 cm 1.83mg/g and 1.00m, 50 cm, 3.45mg/g) with progressively smaller leaves as generation increases. The cocoyams in hydrocarbon impacted soils generally perform poorer than uncontaminated soil with or without poultry manure by the second and third generation. Poultry manure on soils with re-occurring hydrocarbon contamination exacerbates soil weakening. Mean PAH and mean BTEX concentrations in tubers were 0.001-0.0035 mg/kg and &lt;0.001mg/kg respectively. Cocoyams are not strong BTEX bioactive scavenger but gradually became more concentrated in PAH.

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.

Polycyclic Aromatic Hydrocarbons (PAHs) in paddy soil around Nam Son landfill area, Ha Noi, Viet Nam

The paddy soils were collected in the rice growing fields and the uncultivated lands around the Nam Son domestic waste landfill in Hanoi. The average concentration of 16 US EPA priority PAHs in dry soil was 61.61 ng/g, with a range of 22.15-115.1 ng/g. The higher levels of PAHs in soil samples were observed in cultivated paddy fields near the landfill in comparison with the fields far from the landfill. On the other hand, there was no difference in PAHs levels in cultivated paddy fields near the landfill and along the irrigation water canal. Concentrations of 16 PAHs in paddy soils decreased in the order: 5 rings &gt; 3 rings &gt; 4 rings &gt; 2 rings &gt; 6 rings in this area. The PAH isomeric diagnostic ratios including Fluth/(Fluth+Pyr) ratio (Ave 0.43, a range of 0.17-0.61), BaA/(BaA+Chr) ratio (Ave 0.51, a range of 0.26-0.63), IcdP/(IcdP+BghiP) ratio (Ave 0.71, a range of 0.51-0.90) indicated that the potential main sources emitted PAHs in paddy soils from pyrogenic biomass combustion and coal burning. Compared with the risk threshold causing adverse impacts on the ecological environment from different countries in the world, concentrations of PAHs in the soil surrounding the Nam Son landfill area were still below the affected limit. However, environmental quality around the landfill area still needs to be regularly monitored to take timely measures to protect the environment in this area.