Polycyclic aromatic hydrocarbons in water, sediment and soil of the Songhua River Basin, China

Association between exposure to water sources contaminated with polycyclic aromatic hydrocarbons and cancer risk: A systematic review

The recent scientific focus on polycyclic aromatic hydrocarbons (PAHs) has stemmed from their recognized genotoxic, mutagenic, and carcinogenic properties. This systematic review seeks to evaluate the nexus between exposure to water sources contaminated with PAHs and the associated cancer risk among global populations, encompassing both children and adults. Web of Science (WoS), Cochrane Library, PubMed, ProQuest, Scopus, and Google Scholar, were searched following the PRISMA guidelines, until December 31, 2023. Quality assessment of the selected studies was performed using the Newcastle-Ottawa Scale. The increased lifetime cancer risk (ILCR) attributed to PAH exposure through ingestion and dermal absorption was thoroughly examined across diverse age groups. After extensive searching, screening, and eligibility, 30 articles were included in this review, which was conducted in different parts of the world, including Nigeria (n = 11), China (n = 7), India (n = 4), Iran (n = 3), South Africa (n = 2), Italy (n = 1), Colombia (n = 1), and Iraq (n = 1). Our analysis underscores Nigeria's alarming prevalence of PAH contamination in its rivers, groundwaters, and seawater. Remarkably, the highest cancer risk was identified among children and adults, notably in proximity to the Atlas Cove jetty (seawater) and various Nigerian rivers. This elevated risk is primarily attributed to the combined effects of ingestion and dermal absorption. Furthermore, our findings emphasize the prominent role of combustion-derived and pyrogenic sources of PAH in the examined aquatic ecosystems. This study unequivocally establishes that PAH-contaminated water sources significantly amplify the risk of cancer among both children and adults. The extent of risk variation is influenced by the specific water source, duration of exposure, and age group. Consequently, proactive identification of contaminated water sources and their pollution origins, coupled with targeted educational campaigns, holds promise for reducing the global burden of PAH-related cancer.

Seasonal distribution characteristics and ecological risk assessment of phthalate esters in surface sediment of Songhua River basin

Phthalic acid esters (PAEs) are typical industrial chemicals used in China. PAEs have received considerable attention because of their ubiquity and potential hazard to humans and the ecology. The spatiotemporal distributions of six PAEs in the surface sediments of the Songhua River in the spring (March), summer (July), and autumn (September) are investigated in this study. The total concentration of phthalic acid esters (∑6PAEs) ranges from 1.62 × 102 ng g-1 dry weight (dw) to 3.63 × 104 ng g-1·dw, where the amount in the spring is substantially higher (p < 0.01) than those in the autumn and summer. Seasonal variations in PAEs may be due to rainfall and temperature. The ∑6PAEs in the Songhua River's upper reaches are significantly higher than those in the middle and lower reaches (p < 0.05). Dibutyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) are the two most abundant PAEs. The ecological hazard of five PAEs is assessed using the hazard quotient method. DBP and DEHP pose moderate or high ecological risks to aquatic organisms at various trophic levels. PAEs originate primarily from industrial, agricultural, and domestic sources. Absolute principal components-multiple linear regression results indicate that agricultural sources are the most dominant contributor to the ∑6PAEs (53.7%). Guidelines for controlling PAEs pollution in the Songhua River are proposed.

Polycyclic aromatic hydrocarbons in aquatic media of Turkey: A systematic review of cancer and ecological risk

Polycyclic aromatic hydrocarbons (PAHs) have gathered worldwide attention due to their carcinogenicity and toxicity. This paper aims to review and extend current knowledge on PAHs in aquatic environments in Turkey, where expansion of the marine industry has caused contamination concerns. To assess cancer and ecological risks associated with PAHs, we systematically reviewed 39 research articles. Mean measured concentrations of total PAHs ranged from 61 to 249,900 ng L^-1 in surface waters, 1 to 209,400 ng g^-1 in sediments, and 4 to 55,000 ng g^-1 in organisms. Estimated cancer risks from concentrations in organisms were higher than those from surface waters and sediments. Negative ecosystem impacts of petrogenic PAHs were estimated to be larger than those of pyrogenic origin, despite the predominance of the latter. Overall, the Marmara, Aegean, and Black seas are highly-polluted and need remedial action, while further study is needed to confirm the status of other water bodies.

The distribution, sources and health risk of polycyclic aromatic hydrocarbons (PAHs) in sediments of Liujiang River Basin: A field study in typical karstic river

The accumulation of PAHs in sediments of Liujiang River Basin were investigated to disclose the sources, input processes and toxicity risk of PAHs in a typical karstic river. The results revealed the concentrations of ∑₁₅PAHs are ranging from 111.97 to 593.39 ng/g, most of which are centralized in upstream and midstream of Liujiang River. Positive Matrix Factorization identified PAHs are mainly from the mixed combustion of oil and coal, biomass combustion and oil products leaking. Redundancy analysis manifested mixed accumulation should be the main approach of PAHs that inputting sediment. The values of RQ_NCs and RQ_MPCs suggested the moderate contamination of PAHs. The higher HQ and ILCR indicated the ingestion of PAHs are the main way to impact public health, while children should be more susceptible to PAHs. The values of HQ and ILCR indicated the overall low non-carcinogenic risk of PAHs, but relatively high carcinogenic risk of PAHs.

The characteristics of polycyclic aromatic hydrocarbons and heavy metals in water and sediment of dajiuhu subalpine wetland, shennongjia, central China, 2018-2020: Insights for sources, sediment-water exchange, and ecological risk

Polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) are persistent environmental issues. Secondary emissions are produced as a result of climate change and human activity. To observe spatio-temporal variations of PAHs and HMs and to discuss the sources as well as the source or sink of PAHs for sediment and peat, twelve surface sediment and surface water sites were chosen along the direction of the flow to down hole in the Dajiuhu area, simultaneously, surface peat and water samples were collected in peatland. Samples were continuously taken for three years (Sep. 2018, Sep. 2019, and Sep. 2020, respectively). The results showed that PAHs and HMs are common in sediment and peat. PAHs concentration is generally higher in peat and water, while HMs concentration is relatively higher in water and relatively low in sediment and peat, and the ecological risk of sediment was low. HMs in sediment are mainly affected by rock weathering, while PAHs are mainly affected by atmospheric deposition, biomass and coal combustion and vehicle emission. HMs and PAHs can be used as an indicator of rock weathering and human activity in Dajiuhu area, respectively. A water-sediment fugacity analysis revealed that peat is a sink for PAHs, confirming that it has a high capacity for adsorbing organic contaminants, and that sediments are secondary sources of PAHs that can release them into water. Attention should be paid to the increased fugacity fraction (ff) value in peatland, indicating that peat might be converted from a sink to a source of PAHs.

Effects of organic matter on polycyclic aromatic hydrocarbons in riverine sediments affected by human activities

Organic matter (OM) is an important component of riverine environments and a major factor in the migration and transformation of hydrophobic organic substances, such as polycyclic aromatic hydrocarbons (PAHs), to sediments. We studied the distributions, sources, and correlations between PAHs and OM in sediments from the Duliujian and the Beiyun rivers in North China. Sixteen PAHs were detected in the surface sediments at total concentrations ranging from 356 to 4652 ng·g^-1 dry weight, which caused a moderate to high level of pollution. The PAH distributions were significantly and positively correlated with OM (p < 0.01) and higher concentrations were detected downstream of areas affected by human activity. Petroleum, coal, and wood combustion were the main sources of PAHs in riverine sediments, and the sources of OM in sediment included terrestrial and aquatic higher plants, soil, and sewage discharge. The OM accumulated and aged along the river, with increases in the degree of aromaticity and condensation, which led to stronger adsorption of PAHs. Our results will help to promote the management and restoration of contaminated riverine sediments.

Spatial occurrence and sources of PAHs in sediments drive the ecological and health risk of Taihu Lake in China

To study the spatial occurrence, sources, and ecological risks of 16 PAHs, surface sediments had been collected from seven major areas of Taihu Lake, China in April 2021. Results showed that the concentrations of ∑₁₆PAHs varied between 1381.48 and 4682.16 ng g⁻¹, and the contents of BghiP in each sample were the highest. The PAHs concentrations in the sediments near the lakeshore were much higher than those in the central area of the lake. The sedimentary ∑₁₆PAHs were mainly composed of molecular-weight monomers and 4-ring PAHs showed superiority (35.69–45.02%). According to the ratio of PAH monomer, the sedimentary PAHs in Taihu Lake were dominantly derived from the combustion. Through the biological toxicity assessment and the BaP equivalent (BaPE), great biological risks of PAHs monomers i.e. DahA and IcdP were found. Both concentrations of ∑₁₆PAHs and dominant 4–6-ring monomers accompanied by carcinogenic risks in many areas of Taihu Lake increased. It is necessary to strengthen monitoring and take measures to control the input of organic pollutants.

Probabilistic human health-risk assessment and influencing factors of aromatic hydrocarbon in groundwater near urban industrial complexes in Northeast China

Organic pollutants are common in the environment, very difficult to remove, and pose a serious threat to human health. Probabilistic risk assessment advances conservative single-point estimation and brings a new perspective to risk assessment. From 2009 to 2019, we monitored the distribution of major pollutants in an industrial park in Northeastern China. The result showed the maximum concentration of benzene reached 73,680 μg/L in 2009, benzo[a]pyrene reached 36.80 ng/L in 2016. These concentrations are significantly above the levels set by Chinese regulatory agencies. The single-factor index increases year by year, and pollutants gradually spread from the pollution leakage source to surrounding areas. A new method was used to quantify the human health risk from groundwater organic pollution accurately, based on the triangular fuzzy numbers coupled with the Monte Carlo simulation. The Monte Carlo simulation was used to simulate the triangular fuzzy numbers. This simplified the operation between the triangular fuzzy numbers and their function successfully and obtained the risk as a set of values. The results indicated that non-carcinogenic risk was negligible in all age groups (children, adolescents, and adults). Conversely, when it comes to carcinogenic risks, adults were about 50-270 times the tolerable level of risk due to long exposure years and wide skin contact areas. Oral ingestion played an essential role in total exposure (>90%) compared to dermal contact. Control of exposure duration and intake should be prioritized when making decisions to reduce risk uncertainty. Monte Carlo simulation-triangular fuzzy numbers can effectively reduce the risk of uncertainty and reflect the complex conditions of the groundwater environment for small amounts of data or inaccurate data.

Polycyclic aromatic hydrocarbons (PAHs) in surficial sediments from selected rivers in the western Niger Delta of Nigeria: Spatial distribution, sources, and ecological and human health risks

This study assessed the concentrations, sources, and risks of polycyclic aromatic hydrocarbons (PAHs) in sediments from the Rivers Niger, Ase and Forcados in the western Niger Delta. The concentrations of PAHs (in μg kg^-1 dry weight), as determined by gas chromatography-mass spectrometry, in sediments from these rivers varied from 2400 to 19,000, 2930 to 16,100, and from 1620 to 19,800 for the Niger, Ase and Forcados Rivers respectively. High molecular weight (HMW) PAHs were the most prevalent compounds present in these sediments. An assessment of the possible ecological and human health risks suggested high risks for both organisms and humans. The PAH source analysis suggested that sediments from these river systems were contaminated with PAHs arising from burning of biomass, gasoline/diesel emissions, burning of natural gas, and oil spillages.

Determination of Polycyclic Aromatic Hydrocarbons and Their Methylated Derivatives in Sewage Sludge from Northeastern China: Occurrence, Profiles and Toxicity Evaluation

This paper assesses the occurrence, distribution, source, and toxicity of polycyclic aromatic hydrocarbons (PAHs), and their methylated form (Me-PAHs) in sewage sludge from 10 WWTPs in Northeastern China was noted. The concentrations of ∑PAHs, ∑Me-PAHs ranged from 567 to 5040 and 48.1 to 479 ng.g−1dw, which is greater than the safety limit for sludge in agriculture in China. High and low molecular weight 4 and 2-ring PAHs and Me-PAHs in sludge were prevalent. The flux of sludge PAHs and Me-PAHs released from ten WWTPs, in Heilongjiang province, was calculated to be over 100 kg/year. Principal component analysis (PCA), diagnostic ratios and positive matrix factorization (PMF) determined a similar mixed pyrogenic and petrogenic source of sewage sludge. The average values of Benzo[a]pyrene was below the safe value of 600 ng.g−1 dependent on an incremental lifetime cancer risk ILCR of 10⁻⁶. Sludge is an important source for the transfer of pollutants into the environment, such as PAHs and Me-PAHs. Consequently, greater consideration should be given to its widespread occurrence.

Fate and Occurrence of Polycyclic Aromatic Hydrocarbons and Their Derivatives in Water and Sediment from Songhua River, Northeast China

The Songhua River is one of the most populated and oldest industrial areas in Northeast China. To understand the sources and distribution of polycyclic aromatic hydrocarbons and their derivatives, such as 16 priority (PAHs), 33 methylated (Me-PAHs), and 12 nitrated (NPAHs) in river water and sediment, were noticed. The concentrations of ∑PAHs, ∑Me-PAHs, and ∑NPAHs in river water scaled from 135 to 563, 9.36 to 711, and 1.26 to 64.7 ng L−1, with mean values of 286, 310, and 17.9 ng L−1, and those in sediments were from 35.8 to 2000 ng g−1, 0.62 to 394 ng g−1, and 0.28 to 176 ng g−1 (dry weight) with mean values of 283, 103, and 21.7 ng g−1. The compositions proved that two-ring and three-ring compounds of PAHs, NPAHs, and four-ring, six-ring of Me-PAHs were prevalent in water samples; in contrast, four-ring dominated in sediments. Principal components analysis (PCA) and diagnostic ratios confirmed that pollutant source was mixed petrogenic and pyrogenic origin. The fugacity fraction (ƒƒ) was also calculated to explain the trend of sediment–water exchange, high ƒƒ values found in summer, for most HMW PAHs and Me-PAHs that these substances acted as a secondary source of emissions from sediment to water. The risk assessment for water was categorized as high.

Concentrations, distribution and risk of polycyclic aromatic hydrocarbons in sediments from seven major river basins in China over the past 20 years

Polycyclic aromatic hydrocarbons (PAHs) in river sediments in China have been extensively investigated. However, most previous studies only reported information about specific locations. As a result, the distribution and changes of these chemicals in sediments nationwide remain unknown. Based on published data during 1997-2020, we conducted a systematic meta-analysis to understand the concentration, risk and the spatiotemporal variation of PAHs in river sediments from the seven major river systems in China. The report provides a national picture of PAHs in river sediments of China. Among the seven river systems, higher concentrations of sediment PAHs are found in the basins of Liaohe River and Haihe River. In the study sediments, high-molecular-mass (4-6-ring) PAHs were predominated, reflecting the widespread combustion of coal and fossil fuels across China. In addition, PAH source assessment also suggests that raw coal and crude oil are important contributors to PAH concentrations in the rivers in northeastern China. Over the past 20 years, there is no downward trend in the concentrations of Σ₁₆PAHs in sediments in the seven river basins; but the contribution of high-temperature combustion to the pollution has declined. In addition, our calculated risks from sediment PAHs seem to decline between 1997-2006 and 2007-2017 periods, although the differences were not statistically significant (p > 0.05). Of note, the data collection and the risk assessment methods used in this preliminary survey may result in some uncertainty. Our results suggest that the PAHs in river sediments in China still need to be paid attention to due to the complexity of their sources and harms to aquatic organisms.

Estimation of Polycyclic Aromatic Hydrocarbons Pollution in Mediterranean Sea from Volturno River, Southern Italy: Distribution, Risk Assessment and Loads

This study reports the data on the contamination caused by polycyclic aromatic hydrocarbons (PAHs) drained from the Volturno River. The seasonal and spatial distribution of PAHs in water and sediment samples was assessed. The 16 PAHs were determined in the water dissolved phase (DP), suspended particulate matter (SPM), and sediments. A multidimensional statistical approach was used to identify three pollution composite indicators. Contaminant discharges of PAHs into the sea were calculated in about 3158.2 kg/year. Total concentrations of PAHs varied in ranges 434.8 to 872.1 ng g⁻¹ and 256.7 to 1686.3 ng L⁻¹ in sediment samples and in water (DP + SPM), respectively. The statistical results indicated that the PAHs mainly had a pyrolytic source. Considering the sediment quality guidelines (SQGs), the water environmental quality standards (USEPA EQS), and risk quotient (RQ), the Volturno River would be considered as an area in which the environmental integrity is possibly at risk.

Polycyclic aromatic hydrocarbons in surface waters from the seven main river basins of China: Spatial distribution, source apportionment, and potential risk assessment

In this study, we report long-term measurements of Polycyclic Aromatic Hydrocarbons (PAHs) collected from the surface waters of seven river basins across China. The spatial distribution, source apportionment, and potential risk assessment of 16 USEPA designated PAHs were reviewed. Water samples were collected from the Songhua River Basin (SRB), Yangtze River Basin (YtRB), Yellow River Basin (YRB), Pearl River Basin (PRB), Huai River Basin (HuRB), Liao River Basin (LRB), and Hai River Basin (HRB). Our results show that the total PAH concentration in the surface waters from primary river basins ranged from 99.60 to 3805.00 ng/L in the dry season with a geometric mean value of 797.96 ng/L, and from 235.84 to 11,812.20 ng/L in the wet season with a geometric mean value of 820.75 ng/L. In the river basins examined, the geometric concentration of Σ₁₆PAHs ranged from 215.50 ng/L to 1969.91 ng/L, with a median value of 837.73 ng/L. In the decreasing order across seven river basins, the geometric mean Σ₁₆PAHs content varied as: SRB (1969.91 ng/L) > LRB (1155.87 ng/L) > YRB (884.06 ng/L) > PRB (837.73 ng/L) > HuRB (559.10 ng/L) > HRB (261.84 ng/L) > YtRB (215.50 ng/L). Moreover, the total PAH concentration was slightly lower in the dry season than in the wet season. The pollution level of PAHs in North China was higher than in South China. No discernible temporal trend was observed in Σ₁₆PAHs observed in China during the past decade. Overall, PAHs designated for priority control measures were Nap, Phe, and Flu; as 2- and 3-ring PAHs were the dominant compounds in the river basins, accounting for 33.7% and 36.9% of the total PAHs, respectively. Source analysis revealed that coal and biomass combustion were the main contributors to PAHs in the river basins, accounting for about 40% of the total. The geometric mean concentrations of individual PAH, including BaP, BaA, BbF, BkF, Ind, and DaA in some water samples exceeded the environmental quality standards of both China and the United States. According to metrics describing eco-toxicity from water contamination, the river basin was at moderate risk in YtRB, YRB, PRB, HuRB, and HRB, but at high risk in SRB and LRB, suggesting that targeted control measures or remedial actions should be undertaken to decrease PAH contamination in China.

Influencing factors and health risk assessment of polycyclic aromatic hydrocarbons in groundwater in China

Polycyclic aromatic hydrocarbons (PAHs) are a group of persistent organic pollutants. This study investigated the occurrence of 16 PAHs in groundwater of representative regions of China (the cities of Lanzhou, Shijiazhuang, and Golmud and in Du'an County) using a gas chromatograph mass spectrometer. The total concentrations of 16 PAHs (∑PAHs) were in the range 0-29.06 μg/L (average: 594.8 ng/L). Acenaphthylene (Acy) and Naphthalene (Nap) had the highest detected frequency (74.56 %) and highest average concentration (632.7 ng/L), respectively. The average concentration of ∑PAHs in each study area exhibited the following trend: Lanzhou > Golmud > Du'an dry season > Du'an wet season > Shijiazhuang. The dominant PAHs in the study areas comprised mainly 2-4-ring PAHs, i.e., Nap (38.71 %; Shijiazhuang), BaA (40.09 %; Du'an wet season), Ace (16.84 %; Du'an dry season), Nap (43.51 %; Lanzhou), and BaA (57.43 %; Golmud). Overall, the PAHs of 101 samples were derived primarily from combustion and a small number of samples of PAHs originated from petroleum sources. Owing to strong adsorption in the vadose zone, the concentrations of PAHs in Shijiazhuang groundwater were lower than those in the groundwater of Golmud and Du'an. The groundwater in Du'an, Lanzhou and Golmud exhibits potential carcinogenic risk if consumed without further treatment.

Occurrence and probabilistic risk assessment of PAHs in water and sediment samples of the Diep River, South Africa

This study investigated the levels of polycyclic aromatic hydrocarbons (PAHs) in water and sediment samples of the Diep River freshwater system of Western Cape Province, South Africa. A solid-phase extraction - gas chromatography - flame ionisation detection (SPE-GC-FID) method was utilised to simultaneously determine the 16 United States Environmental Protection Agency (US EPA) listed priority PAHs in water and sediment samples. The seasonal averages of individual PAH detected at the studied sites, ranged between not detected (Nd) and 72.38 ± 9.58 μg/L in water samples and between Nd and 16.65 ± 2.63 μg/g in the corresponding sediment samples. The levels of PAHs measured in water and sediment samples were subjected to probabilistic risk assessment to predict the possibility of regulatory values being exceeded. The average percentage exceedence of 63.26 was obtained for PAHs in water samples of the Diep River, while the corresponding average percentage exceedence obtained for sediment sample was 63.71. Sufficient exposure of humans and aquatic organisms to the exceedance levels obtained, would cause adverse health effect.

Concentrations, Possible Sources and Health Risk of Heavy Metals in Multi-Media Environment of the Songhua River, China

Heavy metal pollution in the river environment has been a source of widespread interest due to potential threats to human health and ecosystem security. Many studies have looked at heavy metal pollution in the context of single source-pathway-receptor relationships, however few have sought to understand pollution from a more wholistic multi-media perspective. To investigate potential risks in a more wholistic way, concentrations of six heavy metals (Cd, Cr, Ni, Cu, Zn and Pb) were detected in multi-media (water, sediment and riparian soil) collected from 14 sampling sites in the main stream of the Songhua River. Chemical analyses indicated that the average concentration of heavy metals in water followed: Zn > Cr > Cu > Pb > Ni > Cd, with a different trend observed in sediments and riparian soil: Zn > Cr > Ni > Pb > Cu > Cd. The potential risk was evaluated using the heavy metal pollution index (HPI), Nemerow pollution index (P_N), hazard index (HI) and carcinogenic risk (CR) metrics. Results showed that all HPI values were lower than the critical level of 100 indicating that the levels of these targeted heavy metals were within drinking water safety limits. The P_N indicated that both sediment (2.64) and soil (2.95) could be considered "moderately polluted", with Cd and Zn providing the most significant contributions. A human health risk assessment suggested that the non-carcinogenic risks were within acceptable levels (HI < 1), as was the cancer risk associated with dermal adsorption (CR <10^-6). However, the CR associated with ingestion exposure (4.58 × 10^-6) exceeded the cancer risk threshold (10^-6) indicative of elevated cancer incidence in exposed populations. Health-risk estimates were primarily associated with Cd in the Songhua River. Source apportionment was informed by Pearson correlation analysis coupled with principal component analysis (PCA) which indicated that Cu was mainly derived from natural (geogenic) sources; Cr and Ni were associated with industrial emissions; Pb might be derived from agricultural and transportation sources; Zn might be from industrial, agricultural activities and transportation; while Cd is likely from industrial and agricultural emissions. The source apportionment information could provide the basis for a risk-management strategy focused on reducing Cd and Zn emissions to the riverine environment. Results from this study will provide the scientific knowledge that is needed for measuring and controlling heavy metals sources and pollution characteristics, and identifying the potential cancer risk with different exposure pathways, as well as making effective environmental management policies at catchment or regional scales.

Evidence and impact of map error on land use and land cover dynamics in Ashi River watershed using intensity analysis

Previously, applications of intensity analysis (IA) on land use and land cover change (LULCC) studies have focused on deviations from uniform intensity (UI) and failed to quantify the reasons behind these deviations. This study presents the application of IA with hypothetical errors that could explain non-uniform LULCC in the context of IA at four-time points. LULCC in the Ashi watershed was examined using Landsat images from 1990, 2000, 2010 and 2014 showing the classes: Urban, water, agriculture, close canopy, open canopy and other vegetation. Matrices were created to statistically examine LULCC using IA. The results reveal that the seeming LULCC intensities are not uniform with respect to the interval, category and transition levels of IA. Error analysis indicates that, hypothetical errors in 13%, 19% and 11.2% of the 2000, 2010 and 2014 maps respectively could account for all differences between the observed gain intensities and the UI; while errors in 12%, 21%, and 11% of the 1990, 2000 and 2010 maps respectively could account for all differences between the observed loss intensities and the UI. A hypothetical error in 0.6% and 1.6% of the 1990 map; 1.5% and 4% of the 2000 map; 1.2% and 2.1% of the 2010 map could explain divergences from uniform transitions given URB gain and AGR gain during 1990-2000, 2000-2010 and 2010-2014 respectively. Evidence for a specific deviation from the relevant hypothesized UI is either strong or weak depending on the size of these errors. We recommend that users of IA concept consider assessing their map errors, since limited ground information on past time point data exist. These errors will indicate strength of evidence for deviations and reveals patterns that increase researcher's insight on LULCC processes.

Biological consequences of environmental pollution in running water ecosystems: A case study in zooplankton

Biodiversity in running water ecosystems such as streams and rivers is threatened by chemical pollution derived from anthropogenic activities. Zooplankton are ecologically indicative in aquatic ecosystems, owing to their position of linking the top-down and bottom-up regulators in aquatic food webs, and thus of great potential to assess ecological effects of human-induced pollution. Here we investigated the influence of water pollution on zooplankton communities characterized by metabarcoding in Songhua River Basin in northeast China. Our results clearly showed that varied levels of anthropogenic disturbance significantly influenced water quality, leading to distinct environmental pollution gradients (p < 0.001), particularly derived from total nitrogen, nitrate nitrogen and pH. Redundancy analysis showed that such environmental gradients significantly influenced the geographical distribution of zooplankton biodiversity (R = 0.283, p = 0.001). In addition, along with the trend of increasing environmental pollution, habitat-related indicator taxa were shifted in constituents, altering from large-sized species (e.g. arthropods) in lightly disturbed areas to small-sized organisms (e.g. rotifers and ciliates) in highly disturbed areas. All these findings clearly showed that anthropogenic activity-derived water pollution significantly influenced biological communities. Thus, biotic consequences of human-induced environmental pollution in running water ecosystems should be deeply investigated. More importantly, the findings of biotic consequences should be well integrated into existing monitoring programs to further assess impacts of anthropogenic disturbance, as well as to advance the management of running water ecosystems for conservation and ecological restoration.

Polycyclic aromatic hydrocarbon (PAHs) geographical distribution in China and their source, risk assessment analysis

In China, the huge amounts of energy consumption caused severe carcinogenic polycyclic aromatic hydrocarbon (PAHs) concentration in the soil and ambient air. This paper summarized that the references published in 2008-2018 and suggested that biomass, coal and vehicular emissions were categorized as major sources of PAHs in China. In 2016, the emitted PAHs in China due to the incomplete combustion of fuel was about 32720 tonnes, and the contribution of the emission sources was the sequence: biomass combustion > residential coal combustion > vehicle > coke production > refine oil > power plant > natural gas combustion. The total amount of PAHs emission in China at 2016 was significantly decreased due to the decrease of the proportion of crop resides burning (indoor and open burning). The geographical distribution of PAHs concentration demonstrated that PAHs concentration in the urban soil is 0.092-4.733 μg/g. At 2008-2012, the serious PAHs concentration in the urban soil occurred in the eastern China, which was shifted to western China after 2012. The concentration of particulate and gaseous PAHs in China is 1-151 ng/m3 and 1.08-217 ng/m3, respectively. The concentration of particle-bound PAHs in the southwest and eastern region are lower than that in north and central region of China. The incremental lifetime cancer risk (ILCR) analysis demonstrates that ILCR in the soil and ambient air in China is below the acceptable cancer risk level of 10-6 recommended by US Environmental Protection Agency (EPA), which mean that there is a low potential PAHs carcinogenic risk for the soil and ambient air in China.

Inihibition of mullet (M. liza) brain acetylcholinesterase activity by in vitro polycyclic aromatic hydrocarbon exposure

Polycyclic aromatic hydrocarbons (PAH) have been reported as acetylcholinesterase (AChE) inibitors, although in vitro studies on PAH effects on AChE activity are scarce and have only been performed using electric eel brain extracts. Thus, this study investigated PAH effects on brain AChE activity in a tropical fish species in Southeastern Brazil, mullet (Mugil liza). Mullet specimens were obtained from Guanabara Bay (N = 20), Rio de Janeiro, Brazil. Brain AChE was extracted and exposed to an environmentally relevant concentration of Pyrene, Chrysene, Phenanthrene, and Naphthalene, and PAH metabolites, 2-Naphthol and 1-OH-Pyrene. AChE activity inhibition was observed, although no difference was observed between high- and low- molecular weight PAH. 2-Naphthol was a less potent AChE inhibitor than Naphthalene, albeit non-significantly. Further studies are required, since only one PAH concentration was used herein. Mullet brain extracts seem to be adequate to assess possible neurotoxic PAH effects on fish AChE.

Occurrence and Ecological and Human Health Risk Assessment of Polycyclic Aromatic Hydrocarbons in Soils from Wuhan, Central China

Polycyclic aromatic hydrocarbons are large groups of ubiquitous environmental pollutants composed of two or more fused aromatic rings. This study was designed to evaluate the distribution, potential sources, and ecological and cancer risks of eleven polycyclic aromatic hydrocarbons from Huangpi soils in Wuhan, central China. The soil samples for this study were taken from 0–10 cm and 10–20 cm soil depths. A modified matrix solid-phase dispersion extraction method was applied to extract analytes from the soil samples. A gas chromatograph equipped with a flame ionization detector was used to determine the concentrations of the compounds. The sum mean concentrations of the polycyclic aromatic hydrocarbons were 138.93 and 154.99 µg kg⁻¹ in the 0–10 cm and 10–20 cm soil depths, respectively. Benzo[a]pyrene and fluorene were the most abundant compounds in the 0–10 cm and 10–20 cm soil depths, respectively. The quantitative values of the pyrogenic index, total index, and diagnostic ratio used in this study showed that the polycyclic aromatic hydrocarbons have a pyrogenic origin. The negligible and maximum permissible concentrations values for naphthalene, acenaphthylene, acenaphthene, phenanthrene, anthracene, pyrene, benz[a]anthracene, and benzo[a]pyrene indicated a moderate ecological risk. The incremental lifetime cancer risk values for adults and children showed a low and moderate cancer risk, respectively.

Assessment of the cytotoxic and mutagenic potential of the Jialu River and adjacent groundwater using human-hamster hybrid cells

The Jialu River in China has been seriously polluted by the direct discharge of industrial and domestic wastewater. The predominant contaminants of the Jialu River and its adjacent groundwater were recently investigated. However, the potential genotoxic impact of polluted water on human health remains to be clarified. Here, we used human-hamster hybrid (A_L) cells, which are sensitive for detecting environmental mutagens. We found that the cytotoxicity and mutagenicity of the groundwater in the Jialu River basin were influenced by the infiltration of the Jialu River. Hydrological periods significantly affected the cytotoxicity, but not the mutagenic potential, of surface and groundwater. Further, the mutagenic potential of groundwater samples located <1km from the Jialu River (S_M-2 water samples) was detected earlier than that of groundwater samples located approximately 20km from the Jialu River (S_N water samples). Because of high cytotoxicity, the mutagenic potential of water samples from the Jialu River (S_M-1 water samples) was not significantly enhanced compared with that of untreated controls. To further assess the mutagenic dispersion potential, an artificial neural network model was adopted. The results showed that the highest mutagenic potential of groundwater was observed approximately 10km from the Jialu River. Although further investigation of mutagenic spatial dispersion is required, our data are significant for advancing our understanding of the origin, dispersion, and biological effects of water samples from polluted areas.

Polycyclic aromatic hydrocarbons and organochlorine pesticides in surface water from the Yongding River basin, China: Seasonal distribution, source apportionment, and potential risk assessment

The presence of 17 polycyclic aromatic hydrocarbons (PAHs) and 15 persistent organochlorine pesticides (OCPs) in surface water of the Yongding River Basin was analyzed through GC/MS/MS during the spring and summer at 46 sampling sites. The goal was to investigate their seasonal distribution, possible sources, and potential risk. Our results showed that the total PAH concentration in surface water of Yongding River Basin ranged from 41.60 to 1482.60ng/L with a mean value of 137.85ng/L in the spring, and from 53.53 to 506.53ng/L with a mean value of 124.43ng/L in the summer. The total OCP concentration ranged from <0.08 to 197.71ng/L with a mean value of 7.69ng/L in the spring, and from <0.08 to 93.58ng/L with a mean value of 7.92ng/L in the summer. Moreover, the total PAH concentration was slightly lower in the spring than in the summer, whereas the total OCP concentration was similar between seasons. Source analysis indicated that combustion sources and petroleum sources both contributed to the presence of PAHs. Historical environmental residues and long range atmospheric transport were the major sources of HCH and DDT contamination. The concentrations of total PAHs and single PAHs including benz(a)anthracene, benzo(a)pyrene, benz(b)fluoranthene, and benz(k)fluoranthene in surface water at some sampling sites exceeded the water environmental quality standards of China and several other countries or organizations. This indicated a potential threat to human health from the consumption of aquatic organisms due to PAH bioaccumulation. The concentrations of α-HCH, p,p'-DDE, and p,p'-DDD at several sampling sites exceeded the limit for human health specified in the ambient water quality criteria developed by the US Environmental Protection Agency, which indicated that these pollutants provide potential hazards to the residents around the sampling sites.

Human health risk assessment of ground water contaminated with petroleum PAHs using Monte Carlo simulations: A case study of an Indian metropolitan city

Underground pipelines are frequently used to transport petroleum fuels, through industrial as well as residential zones. Chennai is one of the four largest metropolitan cities of India. The region of interest in this study is located in the northern part of the Chennai. Ground water of this area was contaminated with polyaromatic hydrocarbons (PAHs) from the leaking oil storage tanks and pipe lines. Health risk assessment was conducted for exposure to PAHs in the ground water using incremental life time cancer risk (ILCR) models coupled with benzo[a]pyrene toxic equivalent method. The exposure pathways considered in this study were direct water ingestion and dermal contact under residential scenario. Exposure input parameters were transformed to statistical parameters using lognormal/uniform distributions and resultant probabilities of cancer risk were estimated by performing Monte Carlo simulations. Preliminary remediation goals were predicted using the combination of the cancer risk models of all the exposure routes with the consideration of high-safety risk of 1-in-1 million. Results showed that the cancer risk is predominantly contributed (greater than 98%) by dermal exposure than the oral in both adults and children. The total ILCR is found to be greater than a low safety risk of 1-in-10,000 with higher probability percentages (>90%). The 95th percentile values of the risk were presented in order to address the need for remediation. Appropriate remedial and treatment methods for the subject site were proposed. The results of the study will be useful for the regulatory boards and policy makers in India in understanding the actual impact of the contamination on receptors, setting up final remediation goals and deciding on a specific remedial method.

Numerical simulation of seasonality in the distribution and fate of pyrene in multimedia aquatic environments with Markov chains

This case study investigated the distribution and fate of organic pollutants in aquatic environments based on laboratory experiments and modeling. Pyrene (Pyr) is a hydrocarbon pollutant with adverse effects on aquatic ecosystems and human health, and was thus selected for this case study. The movement of Pyr was primarily influenced by its sorption from water onto sediment, and its desorption from sediment into water. Its elimination was mainly via biodegradation by microorganisms in sediment and by volatilization from water into air. The transport and elimination rates for Pyr were considerably influenced by temperature and moisture. Results of modeling with Markov chains revealed that the elimination of Pyr from water/sediment systems was the most rapid under wet conditions. Under average conditions, a Pyr concentration of 100 μg/L of in water in such a system declined to a negligible level over 250 h. Under wet conditions, this decrease occurred over 120 h. Finally, under dry conditions, it took 550 h to achieve the same degree of elimination.

Human health risk assessment and PAHs in a stretch of river Ganges near Kanpur

The presence of 13 polycyclic aromatic hydrocarbons (PAHs) was measured in a small stretch of river Ganges in Kanpur, using high-performance liquid chromatography equipped with photodiode array detector (HPLC/PDA). Non-carcinogenic risk on human health was calculated in the form of hazardous index. Carcinogenic risk was calculated as chronic daily intake and incremental lifetime cancer risk (ILCR) with the help of monitored PAHs in river water. Due to non-availability of reference dose (RfD) values for all the 13 PAHs, the combined hazardous index for three PAHs was calculated. These values in winter, pre-monsoon, and post-monsoon period varied from 6.37 × 10^-3 (Bithoor) to 1.12 × 10^-2 (Jajmau), 2.89 × 10^-3 (Bithoor) to 8.52 × 10^-3 (Annandeshwar Temple), and 1.80 × 10^-3 (Massacre Ghat) to 6.67 × 10^-3 (Jajmau), respectively. In this study, the carcinogenic risk due to PAHs was calculated in the form of ILCR. ILCR due to benzo(a)pyrene (BaP) varied from 1.39 × 10^-6 (Massacre Ghat) to 1.45 × 10^-5 (Jajmau). ILCR was also calculated with the help of BaP_eq for five age groups of people (adults, teenagers, children, toddlers, and infants). The outcome of the study indicates that there is a need to control pollution of the river water to maintain its quality. Continuous discharge of PAHs into the river poses both human health risk and ecological risk.

River bottom sediment from the Vistula as matrix of candidate for a new reference material

Bottom sediments are very important in aquatic ecosystems. The sediments accumulate heavy metals and compounds belonging to the group of persistent organic pollutants. The accelerated solvent extraction (ASE) was used for extraction of 16 compounds from PAH group from bottom sediment of Vistula. For the matrix of candidate of a new reference material, moisture content, particle size, loss on ignition, pH, and total organic carbon were determined. A gas chromatograph with a selective mass detector (GC/MS) was used for the final analysis. The obtained recoveries were from 86% (SD=6.9) for anthracene to 119% (SD=5.4) for dibenzo(ah)anthracene. For the candidate for a new reference material, homogeneity and analytes content were determined using a validated method. The results are a very important part of the development and certification of a new reference materials.

Spatial-temporal and multi-media variations of polycyclic aromatic hydrocarbons in a highly urbanized river from South China

Comprehensive studies on polycyclic aromatic hydrocarbons (PAHs) within an urban river are urgently needed to carry out strategies to limit their contamination and dispersal. Here, we analyzed 16 PAH occurrences in water, suspended particulate matter (SPM), and sediment monthly for a year in the Maozhou River mainstream (Shenzhen, South China). Monthly rainfall positively correlated with both total PAH concentrations in filtered water (water PAHs) and SPM. Sediment PAH concentration increased from the river source to estuary. Compared to the earlier record, the sediment PAHs decreased at almost all sites due to the high-molecular-weight PAH (≥4 rings; especially the 4-ring PAH) degradation, except the estuary site that accumulated more low-molecular-weight PAHs (<4 rings). Results suggest that the water and SPM PAHs had similar and recent sources (e.g., rainfall and storm runoff) and actively exchanged with each other. The sediment PAHs had relatively different and complicated sources (fossil fuel combustion: 44.0%; oil pollution: 28.4%; biomass burning: 27.6%), and showed a long-term accumulation effect and increasingly weaker source-sink relation with both water and SPM PAHs from river source to estuary. This study highlights a disconnection in the source and migration mechanism between the water body (including water and SPM) and sediment PAHs.

Polycyclic aromatic hydrocarbons (PAHs) in water and sediment from a river basin: sediment-water partitioning, source identification and environmental health risk assessment

The information on concentration levels, partitioning and sources of pollutants in aquatic environment is quite necessary for pollution treatment and quality criteria. In this work, sixteen priority polycyclic aromatic hydrocarbons (PAHs) recommended by U.S. Environmental Protection Agency in the water and sediment of Yinma River Basin were firstly investigated. Among 16 individual PAHs, naphthalene was the highest average concentration in water samples as well as in sediment samples, 67.2 ng/L and 825.06 ng/g, respectively, whereas benzo(g,h,i)perylene was undetected in water samples nor in sediment samples. For three PAH compositional patterns, concentrations of light (2-3 ring) PAHs were dominant in water and sediment, accounting for 71.69 and 86.98 % respectively. The PAH partitioning in the sediment-water system was studied, results showed that PAH partitioning was in an unsteady state and tended to accumulate in the sediment. The possible sources of PAHs in water and sediment were both identified as a mixed source of petroleum and combustion. The benzo(a)pyrene equivalents (EBaP) values for PAHs in the water and sediment in some sites were relatively higher, suggesting the existence of environmental health risk.

Source and Ecological Risk Characteristics of PAHs in Sediments from Qinhuai River and Xuanwu Lake, Nanjing, China

In order to investigate the residual characteristics, sources, and ecological risk of PAHs in sediment from urban rivers, the sediments of 15 typical sites from Qinhuai River and Xuanwu Lake, which are typical urban rivers and lake, were collected from October 2015 to July 2016; the sources of PAHs in sediment were also identified by several methods. Results showed that ∑PAHs concentration in sediment ranged from 796.2 ng/g to 10,470 ng/g with an average of 2,713.8 ng/g. High molecular weight PAHs with 4-5 rings were most prominent in the sediment during all four seasons. Source characterization studies based on the analysis of diagnostic ratio (triangular plot method), cluster analysis, and positive factor matrix analysis suggested that the PAHs of Qinhuai River Basin were mainly from pyrogenic origin (biomass and coal combustion and vehicular emission), and the petroleum source also cannot be ignored (specially in summer). Most individual PAHs occasionally affect the aquatic organisms. The highest benzo[a]pyrene-equivalent doses (BaPeq dose) appear at the sites of sewage discharge and heavy traffic. So, the PAHs pollution sources of urban water body have obvious seasonal-dependent and human activities-dependent characteristics.

Distribution, sources and ecological risk assessment of polycyclic aromatic hydrocarbons in water and sediments from Tiber River and estuary, Italy

The concentration, source and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in the Tiber River and its environmental impact on the Tyrrhenian Sea (Central Mediterranean Sea) were estimated. The 16 priority PAHs were determined in the water dissolved phase (DP), suspended particulate matter (SPM) and sediments collected from 21 sites in four different seasons. Total concentrations of PAHs ranged from 10.3 to 951.6ngL(-1) and from 36.2 to 545.6ngg(-1) in water (sum of DP and SPM) and in sediment samples, respectively. The compositions of PAHs showed that 2- to 4-ring PAHs were abundant in DP, 4- to 6-ring PAHs were predominant in SPM samples, and 4- to 5-ring PAHs were abundant in sediments. The diagnostic ratio analysis indicated that the PAHs mainly had a pyrolytic source. The toxic equivalent concentration of carcinogenic PAHs was 45.3ngTEQg(-1), suggesting low carcinogenic risk for Tiber River. Total PAHs loads into the sea were calculated in about 3161.7kgyear(-1) showing that this river is one of the main contribution sources of these contaminants to the Tyrrhenian Sea.

A critical and comparative appraisal of polycyclic aromatic hydrocarbons in sediments and suspended particulate material from a large South American subtropical estuary

The Paranaguá Estuarine Complex (PEC) is an important socioeconomic estuary of the Brazilian coast that is influenced by the input of pollutants like polycyclic aromatic hydrocarbons (PAHs). Because of the apparent lack of comparative studies involving PAHs in different estuarine compartments, the aim of this study was to determine and compare PAH concentrations in surface sediment and suspended particulate material (SPM) in the PEC to evaluate their behaviour, compositions, sources and spatial distributions. The total PAH concentrations in the sediment ranged from 0.6 to 63.8 ng g(-1) (dry weight), whereas in the SPM these concentrations ranged from 391 to 4164 ng g(-1). Diagnostic ratios suggest distinct sources of PAHs to sediments (i.e., pyrolytic sources) and SPM (i.e., petrogenic sources such as vessel traffic). Thus, the recent introduction of PAHs is more clearly indicated in the SPM since oil related-compounds (e.g., alkyl-PAHs) remain present in similar concentrations. Further, this matrix may better reflect the current state of the environment at the time of sampling because of the absence of significant degradation.

Distribution of polychlorinated biphenyls, phthalic acid esters, polycyclic aromatic hydrocarbons and organochlorine substances in the Moscow River, Russia

The purpose of this study was to investigate the levels of polychlorinated biphenyl (PCB), phthalic acid esters (PAE), polycyclic aromatic hydrocarbons (PAH) and organochlorine substances (OCP) in the Moscow River water. Some studies have reported the occurrence of these substances in the soil of the Moscow region; however, no study has yet established an overview for these compounds in the Moscow River water. In this study the Moscow River water contamination with PAEs, PAHs and OCPs was determined. Obtained results were associated with the resident area located on the river bank, and the possible contamination sources were considered. The obtained data were compared with the data on the contamination of the different world-wide rivers. This research indicates the further study necessity of the Moscow region to cover more contaminated sites and environmental compartments.

Evaluation and characterization of anti-estrogenic and anti-androgenic activities in soil samples along the Second Songhua River, China

In the present study, re-combined estrogen receptor (ER) and androgen receptor (AR) gene yeast assays combined with a novel approach based on Monte Carlo simulation were used for evaluation and characterization of soil samples collected from Jilin along the Second Songhua River to assess their antagonist/agonist properties for ER and AR. The results showed that estrogenic activity only occurred in the soil samples collected in the agriculture area, but most soil samples showed anti-estrogenic activities, and the bioassay-derived 4-hydroxytamoxifen equivalents ranged from N.D. to 23.51 μg/g. Hydrophilic substance fractions were determined as potential contributors associated with anti-estrogenic activity in these soil samples. Moreover, none of the soil samples exhibited AR agonistic potency, whereas 54% of the soil samples exhibited AR antagonistic potency. The flutamide equivalents varied between N.D. and 178.05 μg/g. Based on Monte Carlo simulation-related mass balance analysis, the AR antagonistic activities were significantly correlated with the media polar and polar fractions. All of these results support that this novel calculation method can be adopted effectively to quantify and characterize the ER/AR agonists and antagonists of the soil samples, and these data could help provide useful information for future management and remediation efforts.

Pyrene is a Novel Constitutive Androstane Receptor (CAR) Activator and Causes Hepatotoxicity by CAR

Polycyclic aromatic hydrocarbons (PAHs) are a class of ubiquitous persistent environmental pollutants which are primarily formed from the incomplete combustion of organic materials. Many potential sources of human exposure to PAHs exist, including daily exposures from the ambient environment or occupational settings. PAHs have been found to cause harmful effects on human health. Here, we evaluated the adverse effects of pyrene, a common PAH, on the liver. The present study demonstrates that pyrene is able to activate mouse constitutive androstane receptor (CAR). CAR protein, as measured by Western blot analysis, was observed to translocate into the nucleus from the cytoplasm in mouse liver after exposure to pyrene. Utilizing CAR null mice, we identified that CAR mediates pyrene-induced hepatotoxicity. Increased relative liver weight, hepatocellular hypertrophy, and elevated serum alanine aminotransferase levels were found in wild-type but not CAR null mice after orally administered pyrene. We further show that pyrene induced the expression of mouse liver metabolism enzymes including CYP2B10, CYP3A11, GSTm1, GSTm3, and SULT1A1, and caused hepatic glutathione depletion in wild-type but not CAR null mice. Moreover, by luciferase reporter assay and quantitative real-time PCR analysis, pyrene was found to be a potential inducer of CYP2B6 expression via activation of human CAR in HepG2 cells and human primary hepatocytes. Our observations suggest that pyrene is a novel CAR activator and that CAR is essential for mediating pyrene-induced liver injury.

Polycyclic aromatic hydrocarbons in Chinese surface soil: occurrence and distribution

In this study, 16 polycyclic aromatic hydrocarbons (PAHs) were analyzed in 157 concurrently collected soil samples in 2005 over China. Higher concentration of ∑16PAHs was found in urban soil, followed by rural and background soil. The results indicated that PAHs in Chinese surface soil showed a primary distribution pattern, which was confirmed by the positive correlation with emission inventory. Based on the results of literature over the past 10 years (2004-2013) in China, the spatial distribution of PAHs in urban and rural soil was established. An obvious geographical distribution with PAH concentration was found, as higher in Eastern China and lower in Middle and Western China. Furthermore, PAH pollution in Chinese riverbank soil was summarized and showed higher levels, indicating their potential sources from polluted rivers. According to our knowledge, this is the first time to comprehensively study the PAH pollution status in Chinese surface soil on the national scale based on monitoring results.

The levels of PAHs and aryl hydrocarbon receptor effects in sediments of Taihu Lake, China

A total of 16 priority polycyclic aromatic hydrocarbons (PAHs) in sediment samples from Taihu Lake were analyzed by instruments, and sediment extracts were assayed for aryl hydrocarbon receptor (AhR)-mediated ethoxyresorufin-o-deethylase (EROD) induction using a rat hepatoma cell line (H4IIE). The cause-effect relationship between the observed EROD activity and chemical concentrations of PAHs was examined. Our results showed that sediment extracts could induce significant AhR effects, and the bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents of raw extracts (TEQ(bio)s) ranged from 2.7 to 39.8 pg g(-1) dw. Chemical analysis showed that 16 PAHs were all detected in all samples, and their total concentrations (Σ16PAHs) ranged from 179.8 to 1,669.4 ng g(-1) dw. The abundance of sedimentary PAHs in the three regions (Meiliang Bay, Gonghu Bay, and Xukou Bay) showed a decreasing trend from the inflow region to the outflow region. Chemical analysis-derived TEQs (TEQ(cal)s) contributed by PAHs ranged from 1.6 to 20.7 pg g(-1) dw. The mean contribution rates (CRs) of PAHs to TEQ(bio)s were 48.9%. In Meiliang Bay, EROD effects of 60% samples were caused by PAHs whose CRs were more than 60%, while in most sampling sites of Gonghu Bay and Xukou Bay, the CRs of PAHs to TEQ(bio)s were basically below 40%. In addition, preliminary ecological risk assessment found that PAHs in sediments have very low ecological impact based on the chemical data of PAHs, while the sediments might pose an unacceptable risk to aquatic organisms and their predators based on the data of TEQ(bio). These findings showed that EROD effects of sediment extracts from Taihu Lake were also caused by other compounds, such as dioxins, polychlorinated biphenyls, etc., together.

Source identification of polycyclic aromatic hydrocarbons in different ecological wetland components of the Qinkenpao Wetland in Northeast China

To determine the distribution and sources of polycyclic aromatic hydrocarbon (PAH), sixteen common PAHs were measured in various wetland components, including groundwater, surface water, sediments and soils collected from the Qinkenpao Wetland of Daqing City in Northeast China. High levels of PAHs were observed in the wetland due to the discharge of industrial wastewater including petrochemical products, such as petroleum and carbolic acid, which can be traced back for nearly three decades. Diagnostic ratios of selected PAH compounds showed that PAHs were generated by a number of mixed sources dominated by petrogenic products. Factor analysis with nonnegative constraints (FA-NNC) was combined with Latin Hypercube Sampling (LHS) simulation, which is effective for using a relatively small sample size while preserving the desirable probabilistic features of simple random sampling, to quantitatively identify sources, source contribution, and uncertainty of PAH contamination. The profiles derived from FA-NNC coupled with LHS were compared with source fingerprints, which were modified based on the first order degradation reaction in different wetland components. Premium gasoline (high-octane) was found to be the largest contributor of PAHs in surface water, groundwater, and sediments (96.0 percent, 61.6 percent and 53.1 percent, correspondingly), while regular gasoline was the dominant source of PAHs in soils (49.0 percent). The results were in agreement with the area׳s environmental data and diagnostic ratio results. Diagnostic ratios and FA-NNC were shown to be an effective methodology for source identification of PAHs in different wetland components.