Quantification and source identification of polycyclic aromatic hydrocarbons in core sediments from Sundarban mangrove wetland, India

Assessment of parent and alkyl -PAHs in surface sediments of Iranian mangroves on the northern coast of the Persian Gulf: Spatial accumulation distribution, influence factors, and ecotoxicological risks

Spatial patterns, potential origins, and ecotoxicological risk of alkylated (APAH) -and parent -(PPAH) polycyclic aromatic hydrocarbons (PAHs) were studied in mangrove surface sediments along the northern coasts of the Persian Gulf, Iran. The mean total concentrations (ngg-1dw) ∑32PAH, ∑PPAHs and ∑APAHs in sediments were 3482 (1689-61228), 2642 (1109-4849), and 840 (478-1273), respectively. The spatial variability was similar among these PAH groups, with the highest levels occurring in Nayband National Marine Park (NNMP). Physicochemical environmental factors, such as sediment grain size, and total organic carbon (TOC) contents, are significant factors of PAH distribution. These findings suggest that PAH pollution level is moderate-to-high, supporting the current view that mangrove ecosystems are under intensive anthropogenic impacts, such as petrochemical, oil and gas loads, port activities, and urbanization. Non-parametric multidimensional scaling (NPMDS) ordination demonstrated that NNMP mangrove is the critical site exhibiting high loading of PAH pollutants. Here, for the first time in this region, Soil quality guidelines (SQGs), Toxic equivalency quotient (TEQ), Mutagenic equivalency quotient (MEQ), and composition indices comprising Mean maximum permissible concentration quotient (m-MPC-Q), and Mean effect range median quotient (m-ERM-Q) methods were used to have a comprehensive risk assessment for PAH compounds and confirmed medium-to-high ecological risks of PAHs in the study area, particularly in the western part of the Gulf, highlighting the industrial impacts on the environment.

Risk assessment of sediment PAH, BTEX, and emerging contaminants in Chanomi Creek Niger Delta, Nigeria

This study assessed the levels of polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, ethylbenzene, and xylene (BTEX), and emerging contaminants in Chanomi Creek. Sediment samples were collected between March 2019 and July 2020 to evaluate the concentrations of PAH, BTEX, and emerging contaminants using GC-MS and GC-FID with Headspace extraction. Results indicated mean PAH concentrations were 22.691 ± 15.09 µg/kg. The highest individual PAH concentrations were fluorene (7.085 µg/kg), naphthalene (4.517 µg/kg), and phenanthrene (3.081 µg/kg). Carbazole (0.828 µg/kg) was discovered as a novel environmental toxin with dioxin-like toxicity and widespread prevalence in sediments. The most common congener (25%) was ethylbenzene, followed by toluene and ortho- and meta-xylene (21%) and benzene (13%). The analysis of diagnostic ratios revealed that the main factors responsible for the presence of PAHs in the study area are the residential use of firewood, emissions from industrial activities, bush burning, and petroleum slicks. The risk assessment indicated that most PAHs exceeded the permissible risk quotient values, suggesting a moderate to high ecological risk. However, cutaneous exposure to PAHs and BTEX was found to have minimal impact on human health, with no significant hazards identified in adults and children. Nevertheless, the study revealed low cancer risks associated with PAH and BTEX compounds for both age groups. The continued discharge of PAHs and BTEX compounds into Chanomi Creek could have significant long-term negative effects on human and aquatic health. Thus, contamination risk awareness programs and the development of stringent contextual thresholds for identified contaminants could enhance environmental and public health protection.

Chronology of PAH and PCB pollution using sediment core in the Golden Horn estuary (Sea of Marmara)

The sources and depositional history of 16 polycyclic aromatic hydrocarbons (PAHs) and 18 polychlorinated biphenyl (PCBs) congeners in the Golden Horn estuary (İstanbul) were investigated using a dated sediment core for the period between 1880 and 2012. The concentrations of PAHs and PCBs were calculated for every 4 cm slices of the sediment core and ranged from 1203.5 to 3441.4 ng/g and 5.4 to 41.4 ng/g, respectively. The diagnostic ratios indicated that the maximum PAH values correspondence to combustion after a crude oil-carrying Romanian tanker (Independenta) accident in the İstanbul Strait in 1979. The historical deposition of PAHs and PCBs in the Golden Horn was influenced by municipal effluent and heavy industrial dischargers approximately 50 years. When the Silahtarağa thermal power plant (TPP) was operating, PCB pollution rose; however, after a thorough rehabilitation effort and the outlawing of PCB use in the 1990s, pollution levels significantly tended to decrease.

Effects of PAHs on meiofauna from three estuaries with different levels of urbanization in the South Atlantic

Estuarine environments are suggested to be the final receivers of human pollution and are impacted by surrounding urbanization and compounds carried by the river waters that flow from the continent. Polycyclic aromatic hydrocarbons (PAHs) are among the contaminants that can reach estuaries and can directly affect marine conservation, being considered highly deleterious to organisms living in these environments. This research investigated the meiofauna of three estuaries exposed to different levels of urbanization and consequently different levels of PAH concentrations, in order to assess how these compounds and environmental factors affect the distribution, structure and diversity of these interstitial invertebrates. A total of 15 major meiofauna groups were identified, with Nematoda being the dominant taxon (74.64%), followed by Copepoda (9.55%) and Polychaeta (8.56%). It was possible to observe significant differences in all diversity indices studied in the estuaries. With the exception of average density, the diversity indices (richness, Shannon index and evenness) were higher in the reference estuary, Goiana estuarine system (GES). On the other hand, the Timbó estuarine system (TES) had the lowest Shannon index value and richness, while the Capibaribe estuarine system (CES) had the lowest evenness value. The latter two estuaries (TES and CES) presented intermediate and high levels of urbanization, respectively. The ecological quality assessment (EcoQ) in the studied estuaries was classified from Poor to Moderate and the estuary with the lowest demographic density in its surroundings, GES, showed a better ecological quality (Moderate EcoQ). A significant distance-based multivariate linear modelling regression (DistLM) was observed between the environmental variables and the density of the meiobenthic community, where PAHs and pH were the main contributors to organism variation. The sediments were characterized by predominance of very fine sand and silt-clay in the most polluted environments, while the control site environment (GES) was dominated by medium grains. The highest concentrations of PAHs were found in the most urbanized estuaries, and directly affected the structure of the interstitial benthic community. The metrics used in the present study proved to be adequate for assessing the environmental quality of the investigated estuaries.

Polycyclic aromatic hydrocarbons (PAHs) in mangrove ecosystems: A review

Polycyclic aromatic hydrocarbons (PAHs) are organic pollutants of increasing concern in the different fields of the environment and human health. There are 16 of them that are recognized as priority pollutants by the US environmental protection agency due to their mutagenic and carcinogenic potentials. Due to their hydrophobicity and stability, they are persistent in the environment and can be transported over long distances. Their toxicological effects on multiple species, including humans, as well as their bioaccumulation in the food web became major topics in organic pollutants research this last decade. In the environment, multiple studies have been conducted on their accumulation in the soil and their degradation processes resulting in numerous review papers. However, the dynamics of PAHs in mangrove ecosystems is not yet completely understood. In this review paper, an exhaustive presentation of what is known about PAHs and their transfer, accumulation, and degradation in mangrove ecosystems is offered. This article brings to light the knowledge already acquired on the subject and the perspective research necessary to fully comprehend PAHs dynamics in mangrove ecosystems.

Past, present and future trends of selected pesticidal and industrial POPs in Kuwait

Given the background of current global initiatives for controlling persistent organic pollutants (POPs), an overview of the scientific knowledge about the POPs issues in Kuwait is presented in this study. Both acute and chronic exposure to POPs can be associated with a wide range of deleterious health effects, including illness and death. POPs have drawn significant political and scientific interest in their fate and actions, particularly where local releases have resulted in dispersed contamination far from the source regions. These concerns inevitably led to the establishment of the Stockholm Convention (SC) on POPs. In recent years, Kuwait has carried out a wide variety of environmental research, in particular, on the monitoring of POPs in different matrices. The technological development facilitated to achieve the opposite monitoring of pesticidal and industrial POPs. The majority of these POPs are from a point source. Kuwait does not have pesticide manufacturing facilities and has not produced pesticides for POPs in the past. In the agriculture sector, Kuwait primarily imports pesticides for pest and disease control. This review encompasses the historical presence and current status of (pesticidal) organochlorine pesticides (OCPs) and (industrial POPs) PCBs and PBDEs in Kuwait based on the export, import, consumption and usage. This research also contrasts pesticide and industrial POP data from various Kuwaiti environmental matrices with data from other parts of Asia, the EU, the USA and Africa.

Presence of polycyclic aromatic hydrocarbons among multi-media in a typical constructed wetland located in the coastal industrial zone, Tianjin, China: Occurrence characteristics, source apportionment and model simulation

In-depth understanding and accurately predicting the occurrence and fate of polycyclic aromatic hydrocarbons (PAHs) in constructed wetlands (CWs) is extremely crucial for optimizing the CWs construction and strengthening the risk control. However, few studies have focused on the PAHs among sediment-water-plant and model simulation in CWs. In this study, sediment, surface water and reed samples were gathered and analyzed from a typical CW. The concentrations of 16 PAHs (Σ₁₆PAHs) in sediments, surface water and reeds ranged from 620 to 4277 μg/kg, 114 to 443 ng/L and 74.5 to 362 μg/kg, respectively. The coefficients of variation (CV) were calculated as 0.796, 0.431 and 0.473 for the above three media respectively, indicating that the spatial distribution variation was medium intensity. The fugacity fraction (ff) suggested that sediments might act as the secondary release source of most PAHs. According to the diagnostic ratios and principal component analysis-multiple linear regression (PCA-MLR), PAHs in this CW mainly come from fossil fuels combustion and petroleum leakage. PAHs in sediments showed high ecological risk at water inlet and moderate risk at the other functional zones, while low risks for surface water at all functional zones. Although the human health risk assessment indicated relatively low cancer risk, the health risk still cannot be ignored with the continuous input and accumulation of exogenous PAHs. A mathematical model covering the hydraulics parameters and composition characteristics of the wetland was established, and its reliability was verified. The simulated results obtained by the established model were basically consistent with the measured values. In addition, the total remove efficiency of PAHs in surface water was 40.2%, which calculated by the simulated model. This work provides helpful insight into the comprehension of occurrence and fate of PAHs among multi-media in CWs.

Environmental impact and human health risk assessment of polycyclic aromatic hydrocarbons (pahs) in raw milk from free-ranging cattles in northwest nigeria

Polycyclic aromatic hydrocarbons (PAHs) were determined in raw milk from Northwest Nigerian cattle (cow, goat and sheep) as indicators in assessing the current pollution status of the region. In Northwest Nigeria, most animals are free rangers with the likelihood that PAHs have been taken up by these animals on the process of drinking PAHs contaminated surface waters, eating road-side grasses, and soils. A total of 42 composite milk samples were collected by milking 3-5 animals. PAHs were extracted after saponification of the milk fats through sonication using dichloromethane/hexane mixture and the five ascertained most abundant PAHs are: Phe > BaP > Chr > Fla. > Pyr using gas chromatography-flame ionization detector (GC-FID). The diagnostic ratios showed that combustion is the major pathway of PAHs emission in the study area which judging from the economic level of the area, could be attributed to vehicular exhaust emission, use of firewood, industrial fumes, waste incineration and bush burning at the beginning of the farming season. The values of PAHs showed no significant variations (p > 0.05), either between the milk types (cow, goat and sheep) or between the seven states' milk samples, indicating a similar source of the PAHs. The European Food Safety Authority set 2 μg/kg w/w BaP as a marker for the occurrence of PAHs contamination and assessment of likely effect of carcinogenic PAH in foodstuffs, the value of BaP obtained was however much higher even though raw milk is about 80% water. Most PAHs have carcinogenic effects on humans and induce various cancers. Therefore there should be a reduction in the bush burning at the beginning of the farming season, use of firewood and other pronounced sources of PAHs in the region.

Pollution investigation and risk assessment of polycyclic aromatic hydrocarbons in soil and water from selected dumpsite locations in rivers and Bayelsa State, Nigeria

The transfer ratio of polycyclic aromatic hydrocarbons (PAHs) from soil dumpsite to borehole water is dependent of polluting source and exposure matrices that causes immerse health risk to man and environment over a period of time. PAHs were assessed in selected soil dumpsite and borehole water located at Rivers state (Eleme, Eliozu, Eneka, Oyigbo, and Woji) and Bayelsa state (Yenagoa), Nigeria. Soil samples were collected at four different points 30 m (North, South, East and West) locations at a depth of 15 cm for each dumpsite using soil auger while control samples were collected 200 m away (farmland), where there were little anthropogenic activities and no presence of active dumpsites. Borehole water samples were collected from 300 m distance, which were packaged in an amber container, labeled, and transported to the laboratory for analysis. Standard analytical methods were employed. PAHs concentrations were analyzed using gas chromatography- mass spectrometry (GC-MS) after extraction of water and soil using liquid-liquid and soxhlet extraction methods respectively and clean-up of the extracts, thereafter the laboratory data generated were subjected to statistical analysis. Total PAHs (ΣPAHS) concentrations in soil samples from the study sites ranged from 2.4294 mg/kg in Yenagoa to 5.1662 mg/kg in Eleme while in water samples the total PAHs ranged from 1.3935 mg/L in Woji to 3.009 mg/L in Eleme. The total PAH concentrations in the soil were above the Agency for Toxic Substances and Disease Registry levels of 1.0 mg/kg for a considerably contaminated site except for the control sites. The total concentration of carcinogenic PAHs ranged from 0.0038 to 1.1301mg/kg in soil samples and 0.0014 to 0.9429 mg/L in borehole water samples, therefore raising concern of human exposure via food chain. The results indicate that low molecular weight PAHs were more dominant than high molecular weight PAHs in both soil and water samples, however molecular diagnostic ratio shows that pyrogenic activities are major sources of PAHs as compared to petrogenic origin. Multivariate analysis (principal component analysis and Pearson correlation) showed strong negative correlation implying that they were from dissimilar sources and different migratory route. Cancer and non-cancer risk showed that children were more at risk compared to adults, where inhalation exposure were major contribution as compared to ingestion and dermal exposure, as such there is a need to implement regulatory laws on indiscriminate release of PAHs contaminants to maintain sustainability.

Spatial and temporal variations of PAHs in surface sediments of estuarine and coast of CanGio wetland, Vietnam

Surface sediments from estuarine and coast of CanGio wetland (CGW) of Hochiminh City, Vietnam, were investigated to identify the spatial and temporal variations of polycyclic aromatic hydrocarbons (PAHs). The total PAHs showed wide variation but similar to patterns observed (F = 0.901, p = 0.46) in LongTau (31 ± 77 ng/g dry weight, n = 13), SoaiRap (53 ± 81, n = 4), ThiVai (60 ± 62, n = 10) estuaries, and coastal areas (112 ± 211, n = 9). A decreasing trend in the wet season (F = 8.8, p = 0.01) reflected that inland sources such as wastewater discharged and atmospherically transported contaminants contributed to PAHs in sediments. The risk posed by the PAHs in the coastal and estuarine areas of CGW is still negligible. The present study provides baseline data, which can be used for regular monitoring and future strategy of environmental protection for the study area.

A Bis-Acridinium Macrocycle as Multi-Responsive Receptor and Selective Phase-Transfer Agent of Perylene

A bis-acridinium cyclophane incorporating switchable acridinium moieties linked by a 3,5-dipyridylanisole spacer was studied as a multi-responsive host for polycyclic aromatic hydrocarbon guests. Complexation of perylene was shown to be the most effective and was characterized in particular by a charge-transfer band as signal output. Effective catch and release of the guest was triggered by both chemical (proton/hydroxide) and redox stimuli. Moreover, the dicationic host was also easily switched between organic and perfluorocarbon phases for applications related to the enrichment of perylene from a mixture of polycyclic aromatic hydrocarbons.

Risk assessment of PAHs and N-PAH analogues in sediment cores from the Niger Delta

Chemical-surveys of sediments are source of information about historical-pollution in aquatic-ecosystems, because ecological/human-health risks may arise from polycyclic-aromatic-hydrocarbons (PAHs) and nitrogen-PAHs presence in aquatic-environments, particularly sediments, where they partition. Despite this, sediment-PAHs/N-PAHs have not been reported in the Niger Delta. This study investigated vertical-profiles of PAHs/N-PAHs in 2 cm-intervals-segments from Bonny Estuary, Niger Delta. Analysis showed that ƩPAHs/ƩN-PAHs in segments ranged from 8699 to 22,528 μg/kg and 503 to 2020 μg/kg, respectively. Abundant-PAH/N-PAH are 2,6-dimethyl-naphthalene and benzo[a]acridine. PAHs/N-PAHs in the samples appeared to be from petrogenic and pyrogenic-sources. Petrogenic-PAHs/N-PAHs were predominated by 2-, 3-rings, alkylated-substituents, while, pyrogenic-PAHs/N-PAHs were dominated by 4-, 5-, 6-rings. Surface-sediments were dominated by petrogenic-PAHs/N-PAHs while, deeper-cores were heavily-contaminated with pyrogenic-PAHs/N-PAHs. ƩPAHs exceeded the ISQGs and PELs of CSQGs. Ʃ-quinoline/Ʃ-acridine exceeded the guidelines for protection of aquatic-life. Furthermore, there are concerns over toxic-ratios >70% in the estuary. Such surveys may be helpful in future sediment-management-decisions for contaminated-systems and long-term-monitoring of sediments to assess remediation/recovery. CAPSULE: Distinct sources of PAHs and N-PAHs exist in the Niger Delta ecosystem and, there are concerns over toxic ratios >70% in the oil rich region and the potential for adverse biological effects.

Assessment of polycyclic aromatic hydrocarbon contamination in the Sundarbans, the world's largest tidal mangrove forest and indigenous microbial mixed biofilm-based removal of the contaminants

The distribution of polycyclic aromatic hydrocarbons (PAHs) in the surface water and sediments in five regions of the Indian Sundarbans was assessed. The capability of microbial biofilm communities to sequester PAHs in a biofilm-promoting vessel was evaluated. The total PAH concentration of water and sediments ranged from undetectable to 125 ng ml^-1 and 4880 to 2 × 10⁴ ng g^-1 dry weight respectively. The total PAHs concentration of sediments exceeded the Effects Range-Low value and the recommended Effects Range-Median values, implying the PAHs might adversely affect the biota of the Sundarbans. Pyrogenic and petrogenic sources of PAH contamination were identified in most of the sampling sites. Indigenous biofilms were cultivated in a patented biofilm-promoting culture vessel containing liquid media spiked with 16 priority PAHs. Biofilm-mediated 97-100% removal efficiency of 16 PAHs was attained in all media. There was no significant difference between the mean residual PAH from the liquid media collected from hydrophobic and hydrophilic flasks. Residual amounts of acenaphthene (Ace), anthracene (Ant), benzo(b)fluoranthene [B(b)F], benzo(a)pyrene [B(a)P] and benzo(g,h,i)perylene [B(g,h,i)P] showed differences when cultivated in hydrophobic and hydrophilic flasks. The mean residual amounts of total PAHs extracted from biofilm biomasses were variable. A biofilm obtained from a specific sampling site cultured in the hydrophobic flask showed higher PAH sequestration when compared to the removal attained in the hydrophilic flask. Relative abundances of different microbial communities in PAH-sequestering biofilms revealed bacterial phyla including Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria, Chloroflexi and Planctomycetes as well as members of Ascomycota phylum of fungi. The dominance of Candida tropicalis, Clostridium butyricum, Sphingobacterium multivorum and Paecilomyces fulvus were established.

Concentration and sources of polycyclic aromatic hydrocarbons in some commercial herbal drugs used for cholera treatment in southwest Nigeria

The aim of this study was to investigate the cancer risk that could be incurred from the use of some anti-cholera herbal drugs sold in Southwest Nigeria. Three most popular anti-cholera herbal drugs were studied. The cancer risk estimation for the drugs at studied population ranges from 7.119 to 0.338 x 10-8 in children, 9.563 to 0.129 x 10-8 in preteen and 9.541 to 5.196 x 10-8 in adult. The cancer risk estimated values are below the USEPA set value 1 x 10-6. This established that the use of these herbal drugs might not lead to cancer if consumed at low dosage.

Distribution and sources of organic contaminants in surface sediments of Hooghly river estuary and Sundarban mangrove, eastern coast of India

This study investigated polycyclic aromatic hydrocarbons (PAHs) and organochlorine compounds such as polychlorinated biphenyls (PCBs) and DDT-related pesticides in surface sediments of Hooghly estuary and the Sundarban mangrove wetlands. Concentrations of ∑₁₇PAH, ∑₁₈₂PCB and ∑₆DDT ranged from 15.4 to 1731, not detected (nd) to 13.5 and nd to 8.97 ng g^-1 dry weight, respectively. Low levels of PCBs and low to moderate concentrations of DDTs and PAHs reflected recent development in West Bengal, which was dominated by agriculture and multifarious industries in the past. Diagnostic ratios suggested that major sources of PAHs are combustion processes, DDTs are input by agriculture, antifouling paints and public health campaigns, and organochlorines are predominantly from industrial origin. Heavier PCB congeners suggest local sources and short-range transport of such chemicals. Decision makers may use these findings for managing the Hooghly River watershed in order to promote a sustainable development on the eastern coast of India.

Bioaccumulation and Cycling of Polycyclic Aromatic Hydrocarbons (PAHs) in Typical Mangrove Wetlands of Hainan Island, South China

Mangrove wetlands are important coastal ecosystems in tropical and subtropical regions, and mangrove sediments and tissues often are the pollutant sinks due to their high organic matter contents. Polycyclic aromatic hydrocarbons (PAHs) in the mangrove sediments and tissues of nine species from three typical mangrove wetlands of Hainan Island were studied. The average concentration of PAHs in all mangrove tissues was 403 ng g^-1 dw, with PAHs concentrations in leaf, branch, root, and fruit of 566, 335, 314, and 353 ng g^-1 dw, respectively. PAHs levels were much higher in leaf than in other mangrove tissues, which may be caused partly by atmospheric deposition of PAHs. The dominant individual PAH compounds in mangrove tissues were phenanthrene (41.3%), fluoranthene (14.7%), and pyrene (11.4%), while in sediments were naphthalene (73.4%), phenanthrene (3.9%), and pyrene (3.6%), respectively. The biota-sediment accumulation factors of PAH congeners in the mangrove wetlands showed different patterns, with the most predominant of phenanthrene. The cycling of PAHs in the mangrove wetlands of Hainan Island also were estimated, and the results showed that the standing accumulation, the annual absorption, the annual net retention, the annual return, and the turnover period in all mangrove tissues of the community were 2228 µg m^-2, 869 µg m^-2 a^-1, 206 µg m^-2 a^-1, 663 µg m^-2 a^-1, and 3.4 a, respectively. These results indicated that mangroves are playing an important role in retaining PAHs.

Polycyclic aromatic hydrocarbons in surface waters and riverine sediments of the Hooghly and Brahmaputra Rivers in the Eastern and Northeastern India

Sixteen priority polycyclic aromatic hydrocarbons (PAHs) regulated by the United States Environmental Protection Agency (USEPA) were analyzed in surface waters and riverine sediments of Brahmaputra and Hooghly Rivers, along urban-suburban-rural transects. ∑₁₆ PAHs concentrations were higher in Hooghly riverine sediment (HRS) (Avg, 445 ng g^-1) than Brahmaputra riverine sediment (BRS) (Avg, 169 ng g^-1) dominated by 4-ring PAHs. In contrast, PAHs concentrations in surface water of Brahmaputra River (BRW) (Avg, 4.04 μg L^-1) were comparable with Hooghly River (HRW) (Avg, 4.8 μg L^-1), with dominance by 3-ring PAHs. Toxic PAHs (BaA, Chr, BbF, BkF, BaP, InP and DBA) were dominant in sub-urban transect of HRS (Avg, 387 ng g^-1) and BRS (Avg, 14 ng g^-1). Diagnostic ratios, principal component analysis (PCA) and ring wise composition suggested combustion as the main PAHs source in these riverine belts. In BRS, higher PAHs in suburban and rural transects were attributed to incomplete combustion of fossil fuel and biomass burning. In HRS, >85% of high molecular weight PAHs were found in the industrial areas of the suburban transect possibly associated with the discharge of industrial effluents. Harbor and port activities were other major contributors of HMW-PAHs in Hooghly riverine system. Carcinogenic potency estimated in terms of toxic equivalent (TEQ) was several folds higher in HRS (Avg, 106 ng TEQ g^-1) compared with BRS (Avg, 2.5 ng TEQ g^-1). Mostly low molecular weight PAHs are likely posing a risk to fishes in both the rivers. Risk on edible fish species may be a matter of concern considering the regular consumption of fishes in this region.

PAH and PCB contamination in the sediments of the Venice Lagoon (Italy) before the installation of the MOSE flood defence works

Contamination from polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the shallow water areas of the Venice Lagoon (415 km²) was investigated in the surface (0-5 cm) and sub-surface (5-10 cm) sediments by collecting cores from 380 sites. The concentrations of 14 PAHs (USEPA priority pollutants) and seven PCB indicator congeners were analysed with high-performance liquid chromatography (HPLC) and capillary gas chromatography (GC), respectively. PAH and PCB concentrations ranged from 2.75 to 9980 ng g^-1 d.w. and from 0.01 to 60.1 ng g^-1 d.w., respectively. Their concentrations never exceeded the probable effect level (PEL) stipulated in the respective quality guidelines. In addition, the average total PAH levels expressed as B[a]P toxicity equivalents (total TEQ) were lower in the sediments of the Venice Lagoon than in other literature-reported zones in the Mediterranean. PAH profiles and ratios showed that they originated not only largely from high-temperature pyrolytic processes attributable primarily to the burning of fossil fuels but also partly from petroleum spillage. Comparison of tetra-to-hepta PCB congeners enabled the PCB profiles observed in the lagoon environment to be characterised as Aroclor 1254 and 1260 (1:1). Compared to other marine coastal areas and harbours in the Mediterranean, the Venice Lagoon sediments showed a low mean value but a wide range of concentrations. The estimation of PAH and PCB inventories indicated the low contribution of atmospheric deposition relative to local sources.

Seasonal Distribution, Source Identification, and Toxicological Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Sediments from Wadi El Bey Watershed in Tunisia

Surface sediments were collected from the Watershed of Wadi El Bey in Tunisia to evaluate the degree of polycyclic aromatic hydrocarbons (PAHs) contamination. Sediments were collected during different seasons in 14 sites that received wastes from domestic effluent, industrial discharge, and agricultural drainage wastes. Twenty-six individual PAHs were analyzed. The total PAH contents (Σ PAHs) in surface sediments showed wide variability, ranging from 6.89 ± 0.05 to 340 ± 0.1 ng g^-1. The 4-, 5-, and 6-ring compounds were the most abundant PAHs detected at the majority of sites. Diagnostic concentration ratios between pairs of PAHs and molecular indices, calculated with the purpose of drawing information about pollution sources, indicated that PAHs were of both petrogenic and pyrolytic origins. Toxic contaminants concentrations were determined according to the numerical effect-based sediment quality guidelines (SQGs). PAH levels did not exceed the SQGs, indicating that PAHs seem to pose low and occasional toxicity risks. Total carcinogenicity and mutagenicity (TEQ_BaP and MEQ_BaP) ranged from 0.08 to 65 ng and from 0.02 to 135.0 ng g^-1 of dry weight, respectively. Among the seven carcinogenic PAHs, BaP accounted for the majority of the potency and could potentially be used as a unique indicator of PAH toxicity. This study provides a baseline to promote environmental protection programs and pollution monitoring/control in Watershed and coastal areas.

Vertical profile, contamination assessment, and source apportionment of heavy metals in sediment cores of Kaohsiung Harbor, Taiwan

Six sediment cores collected at the Kaohsiung Harbor of Taiwan were analyzed to evaluate their vertical profiles, enrichments, accumulations, and source apportionments of heavy metals. This was performed to investigate any potential ecological risks posed by heavy metals. Results indicated that the mean heavy metal content (mg kg^-1) in the six sediment cores was as follows: Hg (0.4-6.4), Cd (<0.05-2.4), Cr (18-820), Cu (16-760), Pb (31-140), and Zn (76-1900). The patterns of heavy metal content in the sediment cores differed substantially among the four river mouths. However, the vertical profiles of metals were relatively stable, indicating that wastewater has the constant characteristics and has been discharged into the rivers for a long period of time. Results of pollution assessment of enrichment factor, geo-accumulation index, and pollution load index revealed that river mouths experience severe enrichment, strong accumulation, and high contamination from the primary heavy metals. It was not consistent in the assessment results of mean effect range median quotient, potential ecological risk index, and total toxic unit method. Potential ecological risks caused by Hg in the sediments at Canon River and Love River mouths on aquatic organisms were extremely high. The estimates derived from the receptor modeling of multiple linear regression of the absolute principal component scores indicated that the contributions of the composite heavy metals derived from the Canon River and the Love River on the potential toxicity and risks to the water environment of Kaohsiung Harbor were highest, followed by those derived from Salt River and Jen-Gen River.

Effect of root exudates on sorption, desorption, and transport of phenanthrene in mangrove sediments

The effect of root exudates on the environmental behaviors of phenanthrene in mangrove sediments is poorly understood. In order to evaluate their influence, comprehensive laboratory experiments were performed using batch equilibrium and thin-layer chromatography (TLC) analyses. In the presence of root exudates, sorption of phenanthrene was inhibited, whereas desorption and mobility were promoted, and were elevated as root exudate concentrations increased. Among the three representative low molecular weight organic acids (LMWOAs) (citric, oxalic, and acetic acids), citric acid promoted desorption and mobility of phenanthrene more effectively than the other two. In addition, application of artificial root exudates (AREs) enhanced phenanthrene desorption, and mobility was always lower than that with the same concentration of LMWOAs, suggesting that LMWOAs predominantly affected the fate of phenanthrene in sediments. The results of this study could enhance our understanding of the mobility of persistent organic pollutants in sediment-water system.

Spatio-temporal distribution, source, and genotoxic potential of polycyclic aromatic hydrocarbons in estuarine and riverine sediments from southern India

In order to categorize the distribution, source, and effects of polycyclic aromatic hydrocarbons (PAHs) in aquatic systems of southern India, chemical and toxicological analyses were performed on surface and core sediments, collected from Adyar river, Cooum river, Ennore estuary, and Pulicat lake near Chennai city. The total PAH concentration in surface sediment ranged from 13 to 31,425ng/g with a mean value of 4320ng/g; the concentration was markedly higher in Cooum river compared to that at other sites. The historical PAH dissemination in core samples in the Cooum river, Ennore estuary, and Pulicat lake ranged from 30 to 31,425ng/g, from 8.6 to 910ng/g, and from 62 to 546ng/g, respectively. Surface sediments were predominantly contaminated with low molecular weight (LMW) PAHs. Historical profiles suggest that PAH contamination in the area is now greater than it had been in the past. PAH accumulation in Pulicat lake was distinct from that at other locations where high molecular weight (HMW) PAHs were predominant. DNA damage in HepG2 cells treated with sediment extracts from different locations showed a good correlation with their respective total PAH levels. Statistical analysis revealed that 3-ring and 4-ring PAHs may synergistically contribute to the genotoxic potency compared to others in sediments. The study also showed that a majority of PAHs in the study area indicated a petrogenic origin. Based on the enrichment and toxicological assessment of PAHs in sediments, Cooum river was shown to suffer the highest biological impairment among the studied water bodies.

Vertical profile, source apportionment, and toxicity of PAHs in sediment cores of a wharf near the coal-based steel refining industrial zone in Kaohsiung, Taiwan

Three sediment cores were collected from a wharf near a coal-based steel refining industrial zone in Kaohsiung, Taiwan. Analyses for 16 polycyclic aromatic hydrocarbons (PAHs) of the US Environmental Protection Agency priority list in the core sediment samples were conducted using gas chromatography-mass spectrometry. The vertical profiles of PAHs in the core sediments were assessed, possible sources and apportionment were identified, and the toxicity risk of the core sediments was determined. The results from the sediment analyses showed that total concentrations of the 16 PAHs varied from 11774 ± 4244 to 16755 ± 4593 ng/g dry weight (dw). Generally, the vertical profiles of the PAHs in the sediment cores exhibited a decreasing trend from the top to the lower levels of the S1 core and an increasing trend of PAHs from the top to the lower levels of the S2 and S3 cores. Among the core sediment samples, the five- and six-ring PAHs were predominantly in the S1 core, ranging from 42 to 54 %, whereas the composition of the PAHs in the S2 and S3 cores were distributed equally across three groups: two- and three-ring, four-ring, and five- and six-ring PAHs. The results indicated that PAH contamination at the site of the S1 core had a different source. The molecular indices and principal component analyses with multivariate linear regression were used to determine the source contributions, with the results showing that the contributions of coal, oil-related, and vehicle sources were 38.6, 35.9, and 25.5 %, respectively. A PAH toxicity assessment using the mean effect range-median quotient (m-ERM-q, 0.59-0.79), benzo[a]pyrene toxicity equivalent (TEQ(carc), 1466-1954 ng TEQ/g dw), and dioxin toxicity equivalent (TEQ(fish), 3036-4174 pg TEQ/g dw) identified the wharf as the most affected area. The results can be used for regular monitoring, and future pollution prevention and management should target the coal-based industries in this region for pollution reduction.

Sources, distribution and risk assessment of polycyclic aromatic hydrocarbons in the mangrove sediments of Thane Creek, Maharashtra, India

The sources, distribution and risk assessment of polycyclic aromatic hydrocarbons (PAHs) were investigated in the mangrove sediments of Trombay and Vashi, along the Thane Creek, Maharashtra, India, for a period of 6 months. The results showed that the concentration of Ʃ15 PAHs ranged from 902.58 to 1643.60 and from 930.69 to 1158.30 ng g(-1) in Trombay and Vashi, respectively. Trombay showed significantly higher PAH concentration (p < 0.05) than Vashi. The four carcinogenic PAHs, (benzo(b)fluorathene, benzo(k)fluorathene, Indeno(1,2,3-cd)pyrene and dibenz(a,h)anthracene) accounted for maximum concentration of the total PAHs. Specific PAH diagnostic indices and the molecular index indicated the presence of both pyrolytic and petrogenic sources with the predominance of pyrolytic origin. A positive correlation (r = 0.736, p < 0.05) existed between the benzo(k)fluorathene level and total PAHs, suggesting the use of this compound as a potential molecular marker for PAH pollution in mangrove sediment. Assessments of potential environmental risks associated with PAHs in this study revealed that the sediment was moderately polluted with high molecular weight PAHs. The study reports the baseline data that can be used for regular monitoring of contamination level considering the heavy industrialization and urbanization along the creek and its coastal region.

Vertical profile, sources, and equivalent toxicity of polycyclic aromatic hydrocarbons in sediment cores from the river mouths of Kaohsiung Harbor, Taiwan

Six sediment cores collected at four contaminated river mouths and two harbor entrances in Kaohsiung Harbor (Taiwan) were analyzed to evaluate the sources and potential toxicity of polycyclic aromatic hydrocarbons (PAHs). PAHs presented the wide variations ranging from 369±656 to 33,772±14,378 ng g(-1) at the six sampling sites. The composition of PAHs presented a uniform profile reflecting the importance of atmospheric input from vehicle exhausts or coal combustion in the river mouths. PAHs diagnostic ratios indicated a stronger influence of coal combustion in the Salt River mouth and the prevalence of petroleum combustion and mixed sources in the other rivers and harbor entrances. PAHs toxicity assessment using the mean effect range-median quotient (m-ERM-q: 0.011-1.804), benzo[a]pyrene-toxicity equivalent (TEQ(carc): 22-2819 ng TEQ g(-1)), and dioxin-toxicity equivalent (TEQ(fish): 37-5129 pg TEQ g(-1)) identified the Salt River mouth near the industrial area of the harbor as the most affected area.

Polycyclic aromatic hydrocarbons (PAHs) in the mariculture zones of China's northern Yellow Sea

Polycyclic aromatic hydrocarbons (PAHs) were detected in water and sediment samples collected from three mariculture zones in China's northern Yellow Sea. In these samples, total PAH concentrations ranged from 110.8 ng/L to 997.2 ng/L and 142.2 ng/gdry weight (dw) to 750.2 ng/gdw, respectively. The log KOC values of the various PAH compounds examined in this study increased with the log KOW values, which is consistent with the prediction regarding PAH behavior in the environment. However, these KOC values were lower than the predicted values as a result of the effects of organic matters, which were abundant in the mariculture water. The isomeric ratios of the PAHs in sediment indicated that the source of the PAHs in the mariculture zones were mainly pyrolytic. The TEQ(carc) values of PAHs ranged from 7 ng TEQ/gdw to 92 ng TEQ/gdw, and only a few samples met the safe criterion with respect to individual PAH concentrations.

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.

Spatial distribution and temporal trends of polycyclic aromatic hydrocarbons (PAHs) in water and sediment from Songhua River, China

The spatial and temporal distributions of polycyclic aromatic hydrocarbons (PAHs) in the Songhua River, Harbin, China, were investigated. Seventy-seven samples, 42 water and 35 sediment samples, were collected in April and October of 2007 and January of 2008. The concentrations of total PAHs in water ranged from 163.54 to 2,746.25 ng/L with the average value of 934.62 ng/L, which were predominated by 2- and 3-ring PAHs. The concentrations of total 16 PAHs in sediment ranged from 68.25 to 654.15 ng/g dw with the average value of 234.15 ng/g dw, which were predominated by 4-, 5- and 6-ring PAHs. Statistical analysis of the PAH concentrations shown that the highest concentrations of the total PAHs were found during rainy season (October of 2007) and the lowest during snowy season (January of 2008). Ratios of specific PAH compounds, including fluoranthene/(fluoranthene + pyrene) (Flu/(Flu + Pyr)) and phenanthrene/(phenanthrene + anthracene) (An/(Ant + PhA)), were calculated to evaluate the possible sources of PAH contaminations. These ratios reflected pyrolytic inputs of PAHs in Songhua River water and a mixed pattern of pyrolytic and petrogenic inputs of PAHs in the Songhua River sediments. Ecotoxicological risk levels calculated for PAHs suggested that there were individual PAHs, which can less frequently cause biological impairment in some samples, but no samples had constituents that may frequently cause biological impairment. Total toxic benzo[a]pyrene equivalent of ΣcPAHs varied from 10.03 to 29.7 ng/g dw and from 0.36 to 1.92 ng/g dw for total toxic tetrachlorodibenzo-p-dioxin equivalent. The level of PAHs indicated a low toxicological risk to this area.

Abilities and genes for PAH biodegradation of bacteria isolated from mangrove sediments from the central of Thailand

PAH-degrading bacteria, including Novosphingobium sp. PCY, Microbacterium sp. BPW, Ralstonia sp. BPH, Alcaligenes sp. SSK1B, and Achromobacter sp. SSK4, were isolated from mangrove sediments. These isolates degraded 50-76% of 100 mg/l phenanthrene within 2 weeks. Strains PCY and BPW also degraded pyrene at 98% and 71%, respectively. Furthermore, all of them probably produced biosurfactants in the presence of hydrocarbons. Interestingly, PCY has a versatility to degrade various PAHs. Molecular techniques and plasmid curing remarkably revealed the presence of the alpha subunit of pyrene dioxygenase gene (nidA), involving in its pyrene/phenanthrene degrading ability, located on megaplasmid of PCY which has never before been reported in sphingomonads. Moreover, genes encoding ferredoxin, reductase, extradiol dioxygenase (bphA3A4C) and exopolysaccharide biosynthetase, which may be involved in PAH degradation and biosurfactant production, were also found in PCY. Therefore, we conclude that these isolates, especially PCY, can be the candidates for use as inoculums in the bioremediation.

Distribution and potential sources of polycyclic aromatic hydrocarbons in soils around coal-fired power plants in South Africa

The distribution and potential sources of 15 polycyclic aromatic hydrocarbons (PAHs) in soils in the vicinity of three South African coal-fired power plants were determined by gas chromatography-mass spectrometry. PAH compound ratios such as phenanthrene/phenanthrene + anthracene (Phen/Phen + Anth) were used to provide reliable estimation of emission sources. The total PAH concentration in the soils around three power plants ranged from 9.73 to 61.24 μg g(-1), a range above the Agency for Toxic Substances and Disease Registry levels of 1.0 μg g(-1) for significantly contaminated site. Calculated values of Phen/Phen + Anth ratio were 0.48 ± 0.08, 0.44 ± 0.05, and 0.38 + 0.04 for Matla, Lethabo, and Rooiwal, respectively. Flouranthene/fluoranthene + pyrene (Flan/Flan + Pyr) were found to be 0.49 ± 0.03 for Matla, 0.44 ± 0.05 for Lethabo, and 0.53 ± 0.08 for Rooiwal. Such values indicate a pyrolytic source of PAHs. Higher molecular weight PAHs (five to six rings) were predominant, suggesting coal combustion sources. A good correlation existed between most of the PAHs implying that these compounds were emitted from similar sources. The carcinogenic potency B[a]P equivalent concentration (B[a] Peq) at the three power plants ranged from 3.61 to 25.25 indicating a high carcinogenic burden. The highest (B[a] Peq) was found in samples collected around Matla power station. It can therefore be concluded that the soils were contaminated with PAHs originating from coal-fired power stations.

Arsenic speciation in polychaetes (Annelida) and sediments from the intertidal mudflat of Sundarban mangrove wetland, India

This paper documents the concentration of total arsenic and individual arsenic species in four soft-bottom benthic polychaetes (Perenereis cultifera, Ganganereis sootai, Lumbrinereis notocirrata and Dendronereis arborifera) along with host sediments from Sundarban mangrove wetland, India. An additional six sites were considered exclusively for surface sediments for this purpose. Polychaetes were collected along with the host sediments and measured for their total arsenic content using inductively coupled plasma mass spectrometry. Arsenic concentrations in polychaete body tissues varied greatly, suggesting species-specific characteristics and inherent peculiarities in arsenic metabolism. Arsenic was generally present in polychaetes as arsenate (As(V) ranges from 0.16 to 0.50 mg kg(-1)) or arsenite (As(III) ranges from 0.10 to 0.41 mg kg(-1)) (30-53 % as inorganic As) and dimethylarsinic acid (DMA(V) <1-25 %). Arsenobetaine (AB < 16 %), and PO(4)-arsenoriboside (8-48 %) were also detected as minor constituents, whilst monomethylarsonic acid (MA(V)) was not detected in any of the polychaetes. The highest total As (14.7 mg kg(-1) dry wt) was observed in the polychaete D. arborifera collected from the vicinity of a sewage outfall in which the majority of As was present as an uncharacterised compound (10.3 mg kg(-1) dry wt) eluted prior to AB. Host sediments ranged from 2.5 to 10.4 mg kg(-1) of total As. This work supports the importance of speciation analysis of As, because of the ubiquitous occurrence of this metalloid in the environment, and its variable toxicity depending on chemical form. It is also the first work to report the composition of As species in polychaetes from the Indian Sundarban wetlands.

Occurrence, bioavailability and toxic effects of trace metals and organic contaminants in mangrove ecosystems: a review

Although their ecological and socioeconomic importance has received recent attention, mangrove ecosystems are one of the most threatened tropical environments. Besides direct clearance, hydrological alterations, climatic changes or insect infestations, chemical pollution could be a significant contributor of mangrove degradation. The present paper reviews the current knowledge on the occurrence, bioavailability and toxic effects of trace contaminants in mangrove ecosystems. The literature confirmed that trace metals, Polycyclic Aromatic Hydrocarbons (PAHs), Persistent Organic Pollutants (POPs), Pharmaceuticals and Personal Care Products (PPCPs) and Endocrine Disrupters Compounds (EDCs) have been detected in various mangrove compartments (water, sediments and biota). In some cases, these chemicals have associated toxic effects on mangrove ecosystem species, with potential impact on populations and biodiversity in the field. However, nearly all studies about the bioavailability and toxic effects of contaminants in mangrove ecosystems focus on selected trace metals, PAHs or some "conventional" POPs, and virtually no data exist for other contaminant groups. The specificities of mangrove ecosystems (e.g. biology, physico-chemistry and hydrology) support the need for specific ecotoxicological tools. This review highlights the major data and methodological gaps which should be addressed to refine the risk assessment of trace pollutants in mangrove ecosystems.

Distribution, source identification, and historical trends of organic micropollutants in coastal sediment in Jakarta Bay, Indonesia

We determined concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), linear alkylbenzenes (LABs), and hopanes in coastal sediments collected from Jakarta Bay and Tokyo Bay. PAH concentrations in sediments from Jakarta Bay (257-1511 ng/g-dry) were lower than or comparable to those from Tokyo Bay (1372-1615 ng/g-dry). Ratios of alkyl-PAHs to parent PAHs showed a greater contribution of petrogenic inputs in Jakarta Bay than in Tokyo Bay. This difference is consistent with the higher ratio of hopanes to PAHs in Jakarta Bay. LAB concentrations in Jakarta Bay (geometric mean, 1400 ng/g-dry) were higher than those in Tokyo Bay (661 ng/g-dry). The internal to external (I/E) ratios of LABs in Jakarta Bay (0.92-2.88) were lower than those in Tokyo Bay (2.8-4.8), indicating that Jakarta Bay receives untreated or poorly treated sewage. Significant amounts of tetrapropylene-based alkylbenzenes were detected in several locations in Jakarta Bay, suggesting current usage of the non-degradable surfactants alkylbenzene sulfonates that are banned in many countries. The PCB concentration in Jakarta Bay was 1 order of magnitude lower than in Tokyo Bay, suggesting minimal usage of PCBs in industrial or commercial products in Jakarta. Analyses of a sediment core indicate increasing inputs of PAHs, hopanes, and LABs into Jakarta Bay during recent decades.

Polycyclic aromatic hydrocarbons (PAHs) in surface sediment and oysters (Crassostrea rhizophorae) from mangrove of Guadeloupe: levels, bioavailability, and effects

Surface sediment and oysters (Crassostrea rhizophorae) from the coastlines of Guadeloupe were analysed for polycyclic aromatic hydrocarbons (PAHs) using GC/MS. Biomarkers of oxidative stress were used to assess the response of these oysters to hydrocarbons exposure. The total concentration of PAHs in the sediment ranged from 49 to 1065 ng/g dw, while concentrations in oyster ranged from 66 to 961 ng/g dw. Molecular indices based on isomeric PAHs ratios characterize the pollution sources and show that most of the contaminations in sediment originate from pyrolytic inputs. Bioaccumulation factors (BAFs) have been related to isomeric ratio calculated for oysters in order to refine PAHs sources. The variations of BAFs observed in the different compounds resulted from different uptake pathways in the mangrove oysters according to the type of inputs. Response of biomarkers showed inhibition of catalase and an increase of lipid peroxidation at the station where PAHs concentrations were the highest. Taken together, data obtained point to the relevance of considering environmental conditions as factors influencing biomarker responses in environmental monitoring programs. These data also indicate the need for regular environmental follow-up studies in Guadeloupe.

Polycyclic aromatic hydrocarbons loads into the Mediterranean Sea: estimate of Sarno River inputs

The polycyclic aromatic hydrocarbons (PAHs) pollution in the Sarno River and its environmental impact on the Gulf of Naples (Tyrrhenian Sea, Central Mediterranean Sea) were estimated. The 16 PAHs identified by the USEPA as priority pollutants and perylene were determined in the water dissolved phase (DP), suspended particulate matter (SPM) and sediments. Total PAHs concentrations ranged from 23.1 to 2670.4 ng L(-1) in water (sum of DP and SPM) and from 5.3 to 678.6 ng g(-1) in sediment samples. Source analysis revealed that PAHs mainly came from combustion process. Contaminant discharges of PAHs into the sea were calculated in about 8530 gd(-1) showing that this river should account as one of the main contribution sources of PAHs to the Tyrrhenian Sea.

Polycyclic aromatic hydrocarbons in surface sediments of the Jialu River

The Jialu River, an important branch of the Huaihe River in China, was seriously polluted because of rapid economic growth and urbanization. In order to evaluate the potential for serious environmental consequences as a result of anthropogenic contamination, the distribution of polycyclic aromatic hydrocarbons (PAHs) has been investigated in surface sediment samples collected in connection with field surveys of 19 sites along the Jialu River. The total concentration of the 16 USEPA priority PAHs ranged from 466.0 to 2605.6 ng/g dry weight with a mean concentration of 1363.2 ng/g. Sediment samples with the highest PAH concentrations were from the upper reaches of the river, where Zhengzhou City is located; the PAH levels in the middle and lower reaches were relatively low. According to the observed molecular indices, PAHs originated largely from the high-temperature pyrolytic process. According to the numerical effect-based sediment quality guidelines (SQGs) of the United States, the levels of PAHs in the Jialu River should not exert adverse biological effects. The total benzo[a]pyrene toxicity equivalent (TEQ) values calculated for samples varied from 50.4 to 312.8 ng/g dry weight with an average of 167.4 ng/g. The relationships between PAHs and environmental factors, including chemical properties of sediments, water quality, aquatic organisms, hydrological conditions, and anthropogenic activities, are also discussed. PAHs exerted a potential negative impact on the benthos. Settlement percentage, population density and industrial GDP per capita had a significant influence on the distribution of PAHs.

Polycyclic aromatic hydrocarbons and ecotoxicological characterization of sediments from the Huaihe River, China

The distribution, source, ecological risk and ecotoxicity of polycyclic aromatic hydrocarbons (PAHs) of sediments from 7 sampling sites, named as Xinyang (XY), Huainan (HN), Bengbu (BB), Xuyi (XuY), Fuyang (FY), Mengcheng (MC) and Zhengzhou (ZZ), in the Huaihe River basin, China, have been investigated. The total concentrations of 16 USEPA priority PAHs ranged from 62.9 to 2232.4 ng g⁻¹ dry weight (d.w.) with a mean concentration of 1056.8 ng g⁻¹ d.w. Through the assessment of ecological risk, we found that the levels of PAHs in the Huaihe River should not exert adverse biological effects. The total benzo[a]pyrene toxicity equivalent (TEQ) values calculated for samples varied from 0.01 to 194.1 ng g⁻¹ d.w., with an average of 65.9 ng g⁻¹. The toxicity data were accordant with the chemical analysis results in this study. HN, BB and ZZ showed the greatest pollution extent both in the chemical analysis and the study of ecotoxicological effects.