Polycyclic Aromatic Hydrocarbons Concentrations In Water Research Articles

Anthropogenic impacts on polycyclic aromatic hydrocarbons in surface water: Evidence from the COVID-19 lockdown

The lockdown restrictions against coronavirus disease 2019 (COVID-19) have led to unprecedented reductions in global anthropogenic activities. Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic combustion-induced pollutants, but the influence of anthropogenic responses to COVID-19 on PAH contamination remains largely unknown. Here we quantified the impacts of lockdown restrictions on 16PAH pollution based on the data in concentrations dissolved in the water phase and absorbed on the suspended particulate matter (SPM) in the Elbe River from 2015 to 2021 and determined the changes in source contributions classified by individual years and stations. Results show that the annual average PAH concentrations in water and SPM were determined as 0.055 μg·L-1 and 3.77 mg·kg-1 from 2015 to 2021, respectively. Pronounced declines in PAH on SPM (up to -18 %) were observed during the three lockdowns in Germany from 2020 to 2021. However, dramatic rebounds of anthropogenic activities during the removal of the lockdown led to increases (up to 29 %) in ∑16PAH concentrations compared to the same period in previous years. Through the source apportionment method, vehicle and coal emissions were the two most predominant sources of PAHs in the river. Vehicle contribution decreased during the lockdown, while coal emissions increased by 5 %. Health risks for three age groups were assessed as potential low risk and decreased by 18 % from 1.54 × 10–4 in 2015 to 1.27 × 10–4 in 2019, and rebounded to 1.40 × 10–4 in 2020–2021. The findings of this study highlight the strong consistency between PAH concentrations and anthropogenic intensity, implying that source control from improved cleaner production is an effective pathway for mitigating PAH contamination in the aquatic environment.

Distribution, sources and ecological risks of PAHs and n-alkanes in water and sediments of typically polluted estuaries: Insights from the Xiaoqing River

Seasonal water and sediment samples were collected from the Xiaoqing River estuary and the neighboring sea to study the spatial and temporal distributions, sources and ecological risks of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes. The results showed significant spatial and temporal differences in the concentrations of PAHs and n-alkanes under the influence of precipitation, temperature, and human activities. The concentrations of PAHs in water were lower in the wet season than in the dry season, and those in sediments were higher in the wet season than in the dry season. The concentrations of n-alkanes were higher in the rainy season than in the dry season for both water and sediments. The spatial distributions of PAHs and n-alkanes were estuarine > offshore. The concentration ranges of ∑PAHs in water and sediments were 230.66–599.86 ng/L and 84.51–5548.62 ng/g, respectively, in the wet season and 192.46–8649.55 ng/L and 23.39–1208.92 ng/g, respectively, in the dry season. The proportion of three-ring PAHs in water (57.03% and 78.27% in the wet and dry seasons, respectively) was high, followed by two-ring PAHs (27.31% and 13.59% in the wet and dry seasons, respectively). The proportion of four-ring PAHs was higher in sediments (24.79% and 32.20% in the wet and dry seasons, respectively). The ecological risk of PAHs assessed using the toxicity equivalent quotient and risk quotient was at moderate to moderately high risk levels. The high concentration of n-alkane fraction C16 (611.65–75594.58 ng/L) in the water is indicative of petroleum or other fossil fuel inputs. The main peaks of n-alkanes in river sediments were C27, C29 and C31, indicating higher inputs of plant sources. The sediments in the estuary showed dominance of both short-chain C16 and long-chain C25–C31, indicating a combined input of higher plants and petroleum. The diagnostic ratios of PAHs and n-alkanes indicated that their sources were mainly oil/coal/biomass combustion and petroleum spills attributed to frequent vehicular, vessel and mariculture activities. Given the potential ecological risks of PAHs and n-alkanes in water and sediments, future studies should focus on their bioaccumulation and biotoxicity.

Spatiotemporal distribution and inter-media transfer of polycyclic aromatic hydrocarbons in Shanghai, China: Historical patterns and future trends

Polycyclic Aromatic Hydrocarbons (PAHs) represent pervasive pollutants, posing health risks in urban environments. It is essential to comprehend the spatiotemporal distributions, composition profiles, and inter-media transfer processes of PAHs in various environmental compartments, influenced by both natural changes and anthropogenic activities. This study integrates historical and future spatiotemporally changing environmental parameters, including climate data, GDP, population data, land-use types, and hydrological variables, into the Multimedia Urban Model (MUM). This integration enables the simulation of spatiotemporal distributions and inter-media transfer fluxes of PAHs among six different media from the 2010s to the 2100s under two distinct Shared Socio-economic Pathways (SSP) scenarios in the megacity of Shanghai, China. The MUM model, featuring diverse gridded parameters, effectively captures PAH concentrations and movement across environmental compartments. Results indicate a decreasing trend in PAHs concentrations in the 2100s compared to the 2010s, with PAH concentrations in water, sediment, vegetation, and organic film covering impermeable surfaces under the SSP3–7.0 scenario higher than those of the SSP1–2.6 scenario. Low molecular weight PAHs dominate in the sediment, water, and air, whereas high molecular weight PAHs prevail in the organic film, vegetation, and soil. Sediment and soil serve as the predominant sinks for PAHs. The primary transport processes for PAH movement include air-film, air-soil, film-water, soil-air, and water-air. Almost all transfer fluxes exhibit a declining trend in future periods except for the air-film transport pathway. The principal input and removal routes for PAHs in Shanghai involve the advection of air and water. The study provides essential insights into the environmental behavior of PAHs and informs targeted pollution control in Shanghai. Additionally, it serves as a technical reference for similar pollution prediction research.

Determination of Polycyclic Aromatic Hydrocarbons (PAHs) Concentration in Borehole Water from Orhuworhun Town, Delta State, Nigeria.

The quest for quality water and its importance have made it necessary to assess the potability of the water supply. This investigation was carried out to evaluate the concentration of PAHs in borehole water obtained from Orhuwhorun town in Delta State, Nigeria. The water sample was collected from a resident borehole and stored in a sterile bottle to avoid contamination. The water sample was analyzed for PAHs with the use of a gas chromatography mass spectrometer (GC-MC). The total concentration of PAH in water (?16 EPA PAHs), which are 16, includes chrysene (Chry), benzo[b]fluoranthene (BbF), acenaphthene (Ace), benz[a]anthracene (BaA), acenaphthylene (AcPy), anthracene (Ant), benzo[k]fluoranthene (BkF), benzo[ghi]perylene (BghiP), benzo[a]pyrene (BaP), Indeno[1,2,3- cd]pyrene (IndP), fluoranthene (Flu), dibenz[a,h]anthracene (DahA), naphthalene (Nap), pyrene (Pyr), phenanthrene (Phe), and fluorene (Flu). The mean concentration in this study ranges from 22.729 to 102.109 mg/L. The concentration of dibenz[a,h]anthracene (DahA) was observed to be the highest, while the concentration of Chry was found to be the lowest amongst all Ó16 PAH congeners detected. The result of this study was compared with the U.S. EPA Standard Limit, and all PAH congeners were found to exceed the standard limit, which shows that the sample is not fit for drinking. This significant concentration of PAH in the water can be attributed to various anthropogenic activities and untreated waste containing PAH. Therefore, there is an urgent need for regulatory agencies to make sure that industries check for environmental compliance.

Temporal and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) in the Danube River in Hungary

The Danube is a significant transboundary river on a global scale, with several tributaries. The effluents from industrial operations and wastewater treatment plants have an impact on the river's aquatic ecosystem. These discharges provide a significant threat to aquatic life by deteriorating the quality of water and sediment. Hence, a total of 16 Polycyclic Aromatic Hydrocarbons (PAHs) compounds were analyzed at six locations along the river, covering a period of 12 months. The objective was to explore the temporal and spatial fluctuations of these chemicals in both water and sediment. The study revealed a significant fluctuation in the concentration of PAHs in water throughout the year, with levels ranging from 224.8 ng/L during the summer to 365.8 ng/L during the winter. Similarly, the concentration of PAHs in sediment samples varied from 316.7 ng/g in dry weight during the summer to 422.9 ng/g in dry weight during the winter. According to the Europe Drinking Water Directive, the levels of PAHs exceeded the permitted limit of 100 ng/L, resulting in a 124.8% rise in summer and a 265.8% increase in winter. The results suggest that the potential human-caused sources of PAHs were mostly derived from pyrolytic and pyrogenic processes, with pyrogenic sources being more dominant. Assessment of sediment quality standards (SQGs) showed that the levels of PAHs in sediments were below the Effect Range Low (ERL), except for acenaphthylene (Acy) and fluorene (Fl) concentrations. This suggests that there could be occasional biological consequences. The cumulative Individual Lifetime Cancer Risk (ILCR) exceeds 1/104 for both adults and children in all sites.

Spatial distribution and partition of polycyclic aromatic hydrocarbons (PAHs) in the water and sediment of the southern Bohai Sea: Yellow River and PAH property influences

The marginal Bohai Sea, connected to the northwestern Pacific Ocean, is threatened by human activity. The Yellow River, the second largest river in China, drains large amounts of water, silts, and polycyclic aromatic hydrocarbons (PAHs) into the southern Bohai Sea; however, to what extent the Yellow River inputs influence the spatial distributions and partitions of PAHs in the southern Bohai Sea is not well known. Therefore, this study collected surface water, bottom water, and sediment samples from the southern Bohai Sea and analyzed them to examine the spatial distributions and partitions of 15 priority PAHs. The results showed that PAH concentrations ranged from 26.9 to 50.1 ng L–1 in surface water, 18.8 to 44.1 ng L–1 in bottom water, and 7.4 to 143.9 ng g–1 in sediment, with higher proportions of four-, five-, and six-ring PAHs in sediment than in water. PAH inputs from the Yellow River and sea coastal currents determined the spatial distribution of PAH concentrations in water and sediment, with an overall decrease from the estuary to the southeast. However, the solid dilution effect of input silts from the Yellow River and the liquid dilution effect of water from the Yellow River and Yellow Sea led to lower PAH concentrations in the water and sediment of the southern Bohai Sea than those in other areas of the Bohai Sea. PAH exchange between the atmosphere and seawater led to significantly higher individual PAH concentrations (except for acenaphthylene) in the surface water than in the bottom water, with ratios significantly related to the PAH n-octanol-water partition coefficient, organic carbon-water partition coefficient, and Henry's law constants. These parameters also determined PAH partitioning between the bottom water and sediment. Individual and total PAH concentrations in the sediment were significantly correlated with organic matter, clay, and silt contents. Therefore, the partitions and spatial distributions of PAHs in the southern Bohai Sea comprehensively depend on PAH properties, PAH inputs from the Yellow River and the atmosphere, sea currents, and seawater and sediment properties. The ecological risks posed by individual PAHs in both water and sediment were negligible or acceptable.

Distribution, source, risk and phytoremediation of polycyclic aromatic hydrocarbons (PAHs) in typical urban landscape waters recharged by reclaimed water

A park that had used reclaimed water as the sole water supply for fourteen years, was selected to analyze the distribution, sources and risks of 16 priority polycyclic aromatic hydrocarbons (PAHs) in waters and sediments. The effects of phytoremediation were investigated in waterbodies classified as phytoremediation, transitional and non-phytoremediation areas. Diagnostic ratio (DR) and principal component analysis (PCA) were used to analyze the sources of PAHs, while risk quotient (RQ) was used as risk assessment tool. Results showed that ∑PAH concentrations in sediments ranged from 29.4 to 1245.6 ng‧g−1, with average of 354.3 ng‧g−1, corresponding to a moderate pollution level. The concentration of PAHs in water ranged from 10.6 to 326.3 ng‧L−1, with average of 147.2 ng‧L−1, corresponding to a low pollution level. The ∑PAHs in sediments showed a downward trend from northwest to southeast along with the water flow direction, with average values of 459.5, 362.9 and 246.1 ng‧L−1 in the upstream, midstream and downstream, respectively. In contrast, PAH concentrations in water were consistent with recreational activities in the urban park area. There were 95% of water samples and 72% of sediment samples obtaining the Ant/(Ant + Phe) > 0.1 and Flu/(Flu + Pyr) > 0.5, indicating that coal combustion was the major source of PAHs in both the water and sediment. The RQ∑PAH(NCs) values in water and sediment were all between 1 and 800, while RQ∑PAH(MPCs) reached equal to 0, suggesting that ∑PAHs presented a low ecological risk. Acenaphthene accounted for 28.4% of RQ(NCs), and became the most risk PAH in water column. Aquatic plants effectively removed high-ring PAHs from water and middle-ring PAHs from sediments, reducing the overall risks posed by PAHs.

Distribution, sources and ecological risk assessment of polycyclic aromatic hydrocarbons in waters and sediments from Olt River dam reservoirs in Romania

This study provides important data on the distribution, sources and ecological risks of polycyclic aromatic hydrocarbons (PAHs), in surface waters and sediments collected from dam reservoirs on middle and lower course of the Olt River, the main tributary of the Danube, until the discharge into the Black Sea. A wide variation range of total PAHs concentrations in water (from 1.3 to 46.2 ng/L) and sediment (from 1.78 to 614.04 μg/kg) samples was emphasized by the results. The highest average PAHs concentration in water was recorded in the cold season and the lowest in the summer. In sediments, no differences were observed depending on the sampling period. Spatial distribution of PAHs in waters and sediments was correlated with the main anthropogenic activities along the river course. Regardless of the method used to attribute PAH sources (diagnostic ratios of specific PAHs, principal component analysis and hierarchical cluster analysis), it was confirmed that the potential anthropogenic sources of PAHs were both pyrogenic (incomplete combustion of biomass and coal) and pyrolytic (incomplete combustion of liquid fossil fuels and vehicle exhaust emissions), with a dominant pyrolytic input. Ecological risk assessment based on environmental quality standards, mean effect range-median quotient (m-ERM-Q), toxic equivalency factors (TEFs) and risk quotient (RQ) methods indicated potentially low ecological risks from PAHs. The ecological status of the Olt river waters poses no potential risk, and pollution of surface sediments can be classified as low polluted, except for two sites near industrial activities classified as moderately polluted. Therefore, a regular monitoring of PAHs concentration in the waters and sediments should be performed to prevent further contamination of PAHs in the studied area, especially in densely populated industrial areas.

Probabilistic Risk Assessment of Polycyclic Aromatic Hydrocarbons in a Colombian Reservoir

The purpose of this research was to evaluate the concentrations, sources and ecological risk assessment of sixteen polycyclic aromatic hydrocarbons (PAHs) present in water from the La Fe reservoir, Colombia in the months of October and November of 2017 and 2018. Concentrations of PAHs in water were measured with semipermeable membrane devices (SPMD) which allow obtaining the dissolved concentrations of the PAHs in the reservoir, emphasizing the reactivity and bioavailability in the environment. The PAHs analyses were carried out by means of gas chromatography, coupled with tandem mass spectrometry (GC/MS–MS) with triple quadrupole (QqQ). The environmental risk assessment using the estimation of risk quotient with deterministic and probabilistic method, the predictive no-effect concentration (PNEC) and environmental exposure concentration (EEC) in water indicate a negligibe risk for probabilistic method for all PAHs evaluated (RQ < 0.1).

Polycyclic Aromatic Hydrocarbons: Evaluation of concentrations in environmental media in Bayelsa State

Background and aim Artisanal refining of crude oil is an illegal refining process that contributes to environmental pollution through the release of Polycyclic Aromatic Hydrocarbons (PAHs). PAHs compounds are known for their destructive effects on the environment as well as their harmful effects on human health. This study thus assessed the concentrations of PAHs in water, soil, and fish in communities where artisanal refining of crude oil is practiced in Bayelsa State. Materials and methods This descriptive, comparative study was conducted in Sampou (mildly exposed community), Gbarain, and Nembe (severely exposed communities) in Bayelsa State. Water, fish, and soil samples were collected using pre-existing environmental media collection guidelines and sent to the laboratory for GC-FID determination of the PAH concentrations. The data obtained were analyzed using the Statistical Package for Social Sciences (SPSS) software. Results Mean and (total) PAHs concentration in water samples obtained from Sampou was 3.50 ± 4.51 (59.59) μg/L; Gbarain 1.76 ± 4.35 (29.87) μg/L and Nembe 1.90 ± 4.20 (32.25) μg/L. A significant difference in the concentrations was also identified p-value: of 0.021. The mean concentration of PAHs in soil samples obtained from Sampou was 10.73 ± 15.53 (183.38) μg/kg; Gbarain 12.00 ± 19.57 (204.32) μg/kg and Nembe was 8.49 ± 10.07 (144.48) μg/kg. Finally, the mean concentration in fish samples obtained from Sampou was 5.62 ± 5.92 (95.43) μg/kg; Gbarain 3.81 ± 5.57 (64.75) μg/kg and Nembe 4.61 ± 5.33 (78.35) μg/kg. The difference in these concentrations was however not significant. Source diagnostic ratios of the PAHs in the water included Flt/(Flt + Pyr) ratio of 0.23, 0.16, and 0.21; Ant/(Ant + Phe) ratio of 0.87, 0.76, and 0.87 as well as BaA/(BaA + Chr) ratio of 0.43, 0.51 and 0.66 in Sampou, Gbarain and Nembe respectively. Conclusion Concentrations of total PAHs in water and fish samples obtained from the three communities exceeded the acceptable limits for ƩPAHs of 2.0 μg/L and 2 μg/kg in water and fish respectively stipulated by the United States Environmental Protection Agency and the Nigerian Petroleum Regulatory Authority. ƩPAHs concentrations from the samples obtained from Sampou were also higher than the other two communities. There is a need for regular environmental monitoring of PAH concentrations, especially in oil-producing communities, and a shift of focus toward the elimination of pyrolytic sources of PAH pollution.

Unregulated discharge of wastewater in the Mahanadi River Basin: Risk evaluation due to occurrence of polycyclic aromatic hydrocarbon in surface water and sediments

Exposure to polycyclic aromatic hydrocarbons (PAHs) through contaminated water may adversely affect human health and ecology. Water and sediment samples collected from the Mahanadi River Basin (MRB) were analyzed for the presence of sixteen priority PAHs. Results showed that the concentrations of Σ16 PAHs in water and sediments ranged from 13.1 to 685.4 μg/L and 302.6 to 728.2 ng/g. In river water samples, the highest mean concentrations were recorded for Acenaphthylene (18.73 ± 11.61 μg/L) and Benzo(a)Anthracene (10.11 ± 8 μg/L). On the contrary, the maximum concentration was recorded for Phenanthrene (96.18 ± 50.66 ng/g) and Pyrene (76.69 ± 22.73 ng/g) in sediment samples. Human health risk assessment suggests low risk, with incremental lifetime cancer risk (ILCR) being 37.44 × 10−5 for children and 21.82 × 10−5 for adults. In contrast, ecological risk assessment showed a high toxic equivalent quotient of 40.68 ng/g and mutagenic equivalent quotient of 39.74 ng/g suggesting elevated adverse risk to aquatic species.

Spatial distribution of polycyclic aromatic hydrocarbons in the water–sediment system near chemical industry parks in the Yangtze River Delta, China

The Yangtze River Delta (YRD) is one of the most populated and economically prosperous regions in China and contains numerous chemical industry parks. To understand the distribution and sources of polycyclic aromatic hydrocarbons (PAHs), surface water and sediment samples were collected from areas around the industrial parks. The total concentrations of 19 PAHs in water and sediment were 32.98–286 ng L−1 and 15.14–5355 ng g−1, respectively. The highest PAH concentrations in water and sediment were found in samples from Wuxi city, which were dominated by high molecular weight (HMW) PAHs, and strongly influenced by fine chemical parks. HMW compounds dominated in the sediment with PAHs containing four and five rings accounting for 61% of the sedimentary ΣPAHs, PAHs in water were dominated by low molecular weight (LMW) compounds (PAHs with two and three rings represented >68% of ΣPAHs). The results of isomeric ratio analysis and principal component analysis with multiple linear regression indicated that the PAH concentrations in water and sediment near the YRD chemical parks are strongly influenced by industrial emissions. The fugacity fraction approach was applied to explain the trend for water–sediment exchange of 16 priority PAHs, which showed that net fluxes for most were from the sediment into water. The results indicated that the LMW PAHs were in a non-steady state in the sediment–water system. An ecological risk assessment showed that most sites were low to medium risk, but one site was high risk.

Distribution, Sources, and Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Tributary Waters of the Lower Reaches of the Yangtze River, China

The lower reaches of the Yangtze River are a typical gathering place of chemical industrial parks in China. Polycyclic aromatic hydrocarbons (PAHs) emitted in the production process of chemical enterprises enter the tributary water body through atmospheric deposition and surface runoff, and finally merge into the Yangtze River. In this study, the distribution characteristics, source analysis, and ecological risk assessment of PAHs in a series of typical water samples collected in the tributary waters of the Yangtze River were studied. PAH monomers in the samples were mainly low-ring. The total concentration of PAHs was in the range of 37.27 to 285.88 ng·L-1 with a mean value of 78.31 ng·L-1, while the monomer concentration of PAHs ranged from 0 to 61.35 ng·L-1. The lowest detection rate was benzo[k] fluoranthene and benzo[a] pyrene at 75%. As a toxic PAH monomer, the concentration of benzo[a] pyrene ranged from 0 to 11.08 ng·L-1. According to "Water Quality Standards for Drinking Water Sources (CJ 3020-1993)" of China, the concentration of benzo[a] pyrene in a water sample (S12) located near Wuxi City exceeded the limit of drinking water standards (10 ng·L-1). Compared with the total concentration of PAHs in rivers in some typical regions of the world, the concentration of PAHs in this study was generally at low to moderate levels. According to the source analysis results of the ratio method and principal component analysis, the concentration of PAHs in water was mainly affected by fossil combustion, automobile exhaust, and chemical emissions. To assess the potential ecosystem risk of PAHs in the investigated area, the risk quotient (RQ) was used. In addition to the DBA monomer, the relative quantities (RQs) (replication) of the remaining monomers were greater than 1, and the RQ (MPCs) values in all the monomers were less than 1, indicating that the ecological risk of water samples was at a medium level. From the perspective of long-term environmental exposure, appropriate control measures should be considered to prevent further pollution. The results can provide reference for PAH risk assessment and pollution control of chemical industrial parks in the lower reaches of the Yangtze River.

Distribution, sources, and behavior of PAHs in estuarine water systems exemplified by Salt River, Taiwan

Water, suspended particulate matter (SPM), and sediment samples were collected from Salt River in Taiwan and analyzed the concentrations of 16 types of polycyclic aromatic hydrocarbons (PAHs). The analysis results were used to examine the distribution, source, partition behavior, and potential ecological risks of PAHs in the estuarine water systems. The mean concentration of total PAHs in water, SPM, and sediment samples was 0.485–10.2 μg/L, 26.7–169 mg/kg dw, and 0.343–29.4 mg/kg dw, respectively. The highest concentration was found at the river mouth and decreased toward the river and sea with the tide. The distribution of the diagnostic ratios of PAHs showed that the combustion of coal and petroleum products are the main sources of PAHs in Salt River. The in site organic carbon normalized partition coefficients for SPM-water (K'oc(SPMW)) and sediment-water (K'oc(SedW)) were 2.8–4.5 and 4.6–6.0 (log units), respectively, increasing with the number of rings in PAHs. The values log K'oc(SedW) and log K'oc(SPM-W) showed a significant linear correlation with their octanol-water partition coefficients (p < 0.01), and their slopes were 0.427 and 0.316, respectively. The fugacity fraction was used to evaluate the exchange of PAHs in water-SPM-sediment systems. Results showed that in SPM, 2–4-ring PAHs tend to be released into water, whereas 5–6-ring PAHs in water tend to be adsorbed onto SPM. The exchange of PAHs between water and sediment occurs in the direction of adsorption onto sediment from water. The assessment of the mean risk quotient, total toxicity equivalence, and mean effect range-median quotient of PAHs showed that the PAHs in the water and SPM of Salt River may have moderate to high ecological risk. In sediment, PAHs in the lower reaches and estuary may pose moderate to high ecological risk, whereas PAHs in the middle and upper reaches show low to moderate ecological risk.

Effects of oil spill response technologies on marine microorganisms in the high Arctic

We studied how exposure to oil spill response technologies affect marine microorganisms during Arctic winter and spring. Microorganisms were exposed to chemically dispersed oil (DISP), in situ burnt oil (ISB), and natural attenuated oil (NATT) in mesocosms from February to May. We subsampled the mesocosms and studied the effects of oil in laboratory incubations as changes in biomass of the major functional groups: bacteria, heterotrophic-nanoflagellates, dinoflagellates, ciliates, pico- and nanophytoplankton, and diatoms over two 14-day periods. In winter, the majority of polycyclic aromatic hydrocarbons (PAHs) remained encapsulated in the ice, and the low concentrations of PAHs in water led to minute changes in biomass of the investigated groups. In spring, however, when the PAHs were partially released from the melting ice, the biomass of many functional groups in DISP and NATT decreased significantly, while the changes in ISB were less pronounced. The overall biomass reduction, as observed in this study, could lead to a disrupted transfer of energy from the primary producers to the higher trophic levels in oil affected areas.

Performance of constructed wetlands and associated mechanisms of PAHs removal with mussels

The role of mussels in laboratory-scale constructed wetlands (CWs) where wastewater was contaminated with five typical polycyclic aromatic hydrocarbons (PAHs) (three 3-ring PAHs and two 4-ring PAHs) was investigated in this study. The CWs performance and PAHs removal mechanisms were well studied. Results indicated that these five PAHs improved removal efficiencies of NO3-N but in the case of NH4-N accumulation occurred. Of the five added PAHs, the 4-ring PAHs were more refractory with higher concentrations in effluent than 3-ring PAHs. By monitoring the five PAHs concentration in water, mussels had excellent removal efficiency of the five PAHs (97%). According to the mass balance calculation, mussels promoted plant uptake of five PAHs, contributing 15.2% of five PAHs removal in CWs. The PAHs could also accumulate in mussels through ingested substrate. Thus, mussels presented a positive correlation with five PAHs purification at a depth of 0–10 cm in substrate, which was 34.7 μg/kg lower than the control group. Due to the purification and enhanced aerated degradation, mussels performed better in removing 3-ring PAHs in substrate, decreasing 8.3% for 3-ring PAHs compared to the control. A positive correlation between five PAHs addition and nirS, nrfA genes was observed. However, PAHs showed negative impact on nitrifying bacteria (amoA). The significant correlations between mussels and five PAHs made it possible to improve CWs for PAHs treatment with aquatic faunas.

The effects of dredging and environmental conditions on concentrations of polycyclic aromatic hydrocarbons in the water column

Sediment dredging can cause damage to the marine environment due to mobilization of sediments and contaminants. The effects of dredging and boundary environmental conditions on the concentration of Polycyclic Aromatic Hydrocarbons (PAHs) in water were evaluated during dredging of the Oil Port of Genoa-Multedo (Italy). Results showed that turbidity and PAH concentrations increased in the water during dredging. However, the scenario was complex due to the high number of interacting physical-chemical factors influencing PAH concentrations and transport. Due to these, PAH distribution is different in water, where low-molecular-weight PAHs were predominant (maximum concentration 0.105 μg L−1), and in bottom sediments, where high-molecular-weight PAHs had the highest concentrations (from 299.3 to 1256.5 ng g−1). Moreover, mainly during dredging the PAH concentrations in water were significantly higher inside than outside the port as a consequence of the lower dynamics within the port basin. Turbidity was the main parameter related to PAH concentrations.

Polycyclic aromatic hydrocarbons (PAHs) in an urban river at mid and high latitudes: A case study in Siping, a traditional industrial city in Northeast China

ABSTRACTThe occurrence, spatial distribution, seasonal variation, sources, and ecological risks of polycyclic aromatic hydrocarbons (PAHs) in overlying water and surface sediments from Tiaozi River, which is an urban river running through the downtown of Siping City, a traditional industrial city of northeastern China, were investigated. The total PAH concentrations (ΣPAHs) in water varied from 473.5 to 2674.3 ng/L with a mean value of 1272.6 ng/L and ranged from 601.5 to 2906.3 ng/g with a mean value of 1534.4 ng/g in sediments. Both the individual and total PAH concentrations in water and sediments decreased from upstream to downstream, and the average ΣPAHs between the four seasons in water and sediments decreased in the following order of winter> autumn> spring> summer. The composition of the PAHs was characterized by an abundance of PAHs from 2 rings to 4 rings, and the predominant components were naphthalene, chrysene, and benzo(a)anthracene. The identification of the source indicated that coal combustion could be the main contributor to the PAHs. The equivalent toxic concentrations of benzo[a]pyrene in the water ranged from 11.5 to 33.1 ng/L, which were much higher than the concentration limit, suggesting that PAHs in the water could cause potential risks. The risk assessment of PAHs in sediments also showed that PAHs could cause negative effects on aquatic organisms in this river.

Distribution, fate and risk assessment of PAHs in water and sediments from an aquaculture- and shipping-impacted subtropical lake, China

The spatial-temporal distribution of polycyclic aromatic hydrocarbons (PAHs), their source, and potential health risks were determined in overlying water and surface sediments from Chinese Lake Guchenghu, adjacent commercial mitten crab ponds and the connected Wushen Canal to assess the contamination profile of the area. The total PAHs concentrations in sediment and water were 86.7–1790 ng g−1 dry weight (dw) and 184–365 ng L−1 in summer and 184–3140 ng g−1 dw and 410–1160 ng L−1 in winter. Two- and 3-ring PAHs were the predominant compounds in water, while PAHs with 4–6 rings dominated in the sediment at both upstream and downstream sites. PAHs concentrations in water and sediment correlated significantly. Diagnostic ratios and positive matrix factorization (PMF) analyses indicated a strong influence of pyrogenic sources, principally biomass combustion and vehicle emission, on the concentrations of PAHs. The distribution, source identification, and mean effects range median quotients (mERMQ) analyses suggested that the most contaminated area was located downstream and upstream of the Wushen Canal, followed by Lake Guchenghu and a commercial crab pond area. From an ecological point of view, PAHs posed a potential risk to drinking water sources as the concentrations exceeded the guideline value of 0.05 μg L−1. The risk posed by sediment PAHs appeared to be low except for the downstream sites, which showed a low to medium ecotoxicological risk. The total incremental lifetime cancer risks ranged between 10−7 and 10−5, indicating a potential health risk for the local population when exposed to sediment from the area.

Presence of polycyclic aromatic hydrocarbons in sediments and surface water from Shadegan wetland – Iran: A focus on source apportionment, human and ecological risk assessment and Sediment-Water Exchange

Polycyclic aromatic hydrocarbons (PAHs) contamination in aquatic system is of concern since it may constitute a sink of these contaminants for wetland ecosystem. We investigated pollution characteristics and ecological risks of PAHs by sampling contaminated sediments and water from the Shadegan wetland in Khuzestan province, south-west Iran. Concentrations of total PAHs in water and sediment samples varied from 42 ± 2.3–136 ± 7.5ng/L and 10 ± 0.5–317 ± 14.3µg/kg, respectively. Source apportionment of PAHs by both approaches (Principal component analysis-multiple linear regression (PCA-MLR) and molecular isomeric ratios of specific PAHs), indicated impact of potential anthropogenic PAH sources including oil spill and incomplete combustion, bulrush combustion, vehicular exhaust and fishing boat emissions. Comparing the PAHs concentration with sediments quality guidelines based on the effect range low values/effects range-median values (ERL/ERM) and the threshold effect levels/probable effect levels (TEL/PEL). Also, a risk quotient (RQ) was elaborated for evaluation of potential toxic effects on aquatic ecosystem. Our data showed relatively insignificant adverse impact for most individual compounds. The toxic equivalent quantity (TEQ) was also calculated to estimation the PAHs toxicity. TEQ value of PAHs (1.9µg/kg) was lower than the safe level (600µg/kg). The fugacity fraction approach was applied to explain the trend of the selected PAHs for water–sediment exchange, which showed that the fluxes for most priority PAHs were from water to sediment suggesting no secondary source impact.