Comprehensive and comparative ecotoxicological and human risk assessment of polycyclic aromatic hydrocarbons (PAHs) in reef surface sediments and coastal seawaters of Iranian Coral Islands, Persian Gulf

Differential bioaccumulation and tolerances of massive and branching scleractinian corals to polycyclic aromatic hydrocarbons in situ

Scleractinian corals are capable of accumulating polycyclic aromatic hydrocarbons (PAHs) in reef environments; however, the mechanism behind their PAHs tolerance is unknown. This study investigated the occurrence and bioaccumulation of PAHs in coral reef ecosystems and examined the physiological responses induced by PAHs in coral hosts and their algal symbionts, the massive coral Galaxea fascicularis and branching coral Pocillopora damicornis. G. fascicularis had a higher PAHs accumulation capacity than P. damicornis. Both the coral hosts and algal symbionts preferentially accumulated acenaphthene, dibenzo(a,h)anthracene, and benzo(a)pyrene. The accumulated PAHs by G. fascicularis and P. damicornis hosts was accompanied by a reduction in detoxification ability. The accumulated PAHs could induce oxidative stress in P. damicorni hosts, thus G. fascicularis demonstrated a greater tolerance to PAHs compared to P. damicornis. Meanwhile, their algal symbionts had fewer physiological responses to accumulated PAHs than the coral hosts. Negative effects were not observed with benzo(a)pyrene. Taken together, these results suggest massive and branching scleractinian corals have different PAHs bioaccumulation and tolerance mechanisms, and indicate that long-term PAHs pollution could cause significant alterations of community structures in coral reef ecosystems.

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.

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.

An extensive investigation on human risk associated with PAHs in fish and sediment in Bushehr, Northern of Persian Gulf

Here, a comprehensive study was designed to estimate the human risk assessment attributed to exposure of polycyclic aromatic hydrocarbons (PAHs)in sediment and fish in most polluted shore area in north of Persian Gulf. To this end, a total of 20 sediment and inhabitual Fish, as one of most commercial fish, samples were randomly collected from 20 different stations along Bushehr Province coastline. The 16 different components of PAHs were extracted from sediment and edible parts of inhabitual fish and measured with high-performance liquid chromatography (HPLC) and gas chromatography (GC), respectively. In addition, dietary daily intake (DDI) values of PAHs via ingestion Indian halibut and the incremental lifetime cancer risk (ILCR) attributed to human exposure to sediments PAHs via (a) inhalation, (b) ingestion, and (c) dermal contact for two groups of ages: children (1-11 years) and adults (18-70 years) were estimated. The results indicated that all individual PAHs except for Benzo(b)flouranthene (BbF) and Benzo(ghi) perylene (BgP) were detected in different sediment sample throughout the study area with average concentration between 2.275 ± 4.993 mg.kg-1 dw. Furthermore, Naphthalene (Nap) with highest average concentration of 3.906 ± 3.039 mg.kg-1 dw was measured at the Indian halibut. In addition, the human risk analysis indicated that excess cancer risk (ECR) attributed to PAHs in sediment and fish in Asaluyeh with high industrial activities on oil and derivatives were higher the value recommended by USEPA (10-6). Therefore, a comprehensive analysis on spatial distribution and human risk assessment of PAHs in sediment and fish can improve the awareness on environmental threat in order to aid authorities and decision maker to find a sustainable solution.

Occurrence, sources and risk assessment of polycyclic aromatic hydrocarbons in the coral reef waters of the Lakshadweep Archipelago, Arabian Sea

The compound effects of anthropogenic disturbances on global and local scales threaten coral reef ecosystems of the Arabian Sea. The impacts of organic pollutants on the coral reefs and associated organisms have received less attention and are consequently less understood. This study examines the background levels, sources, and ecological implications of polycyclic aromatic hydrocarbons (PAHs) in the coral reef ecosystems of Lakshadweep Archipelago. Water and particulate matter were collected from four coral Islands (Kavaratti, Agatti, Bangaram and Perumal Par) of Lakshadweep Archipelago during January and December 2022 and analysed for 15 PAHs priority pollutants. The 15 PAHs congeners generally ranged from 2.77 to 250.47 ng/L in the dissolved form and 0.44 to 6469.86 ng/g in the particulate form. A comparison of available data among the coral reef ecosystems worldwide revealed relatively lower PAHs concentrations in the Lakshadweep coral ecosystems. The isomeric ratios of individual PAH congeners and principal component analysis (PCA) indicate mixed sources of PAHs in the water column derived from pyrogenic, low-temperature combustion and petrogenic. The risk quotient (RQ) values in the dissolved form indicate moderate risk to the aquatic organisms, while they indicate moderate to severe risk in the particulate form.

Anthropogenic contribution, transport, and accumulation of Polycyclic Aromatic Hydrocarbons in sediments of the continental shelf and slope in the Mediterranean Sea

A multidisciplinary approach, involving geochemical, sedimentological and oceanographic analyses, was employed to examine the distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in a strongly anthropized area of the marginal Adriatic Sea (Mediterranean basin). The investigation into PAH distribution considered the grain size and biogeochemical properties of the sediments, as well as in relation to the main oceanographic processes and river inputs. Both biogeochemical and hydrographical inputs regulated the sedimentation of organic particles, influencing the distribution of PAHs. The results indicated PAH levels in 116 marine surface sediments ranging from 4 to 235 ng g-1 (average 55 ng g-1). The distribution of PAHs in Adriatic Sea surface sediments aligned with a higher clayey sedimentation in the deeper basin areas of the Middle Adriatic Depression.

Occurrence and distribution of polycyclic aromatic hydrocarbons (PAHs) in marine organisms from Shenzhen coastal waters and human health risk assessment

This study investigated the levels and composition of 16 priority polycyclic aromatic hydrocarbons (PAHs) in marine organisms from South China Sea and assessed their potential health risks. The results revealed that the pollution levels of total PAHs ranged from 3.56 to 392.21 ng/g dw. Notably, 4-ring PAHs constituted the predominant fraction (58.02 %) of the total PAHs, with pyrene being the most abundant congener across all species. Intriguingly, our findings suggested that consuming these organisms might pose a low non-cancer hazard. Nonetheless, benzo[a]pyrene was detected in most species, with levels ranging from non-detectable to 11.24 ng/g dw. The individual lifetime cancer risk levels associated with seafood consumption in studied regions ranged from 1.10 × 10-5 to 1.52 × 10-5, highlighting a potential cancer risk that warrants special attention. These findings emphasize the need to prioritize carcinogenic compounds over total PAHs and underscore the importance of continuous monitoring of PAH pollution in seafood.

Source apportionment and human health risk of PAHs accumulated in edible marine organisms: A perspective of "source-organism-human"

Most PAHs produced by human activities can be absorbed and accumulated by edible organisms and pose a potential hazard to human health. However, the source apportionment and human health risk of PAHs accumulated in edible organisms remains largely unknown. Therefore, we conducted source analysis and health risk assessment based on the PAH concentrations in ten marine fish from coastal areas of Guangdong, China. Results showed that the pollution of PAHs in fish organisms was at "Minimally polluted" level, and that all marine fish had the ability to accumulate PAHs. Risk assessment indicated Carcinogenic risk of PAHs in four populations was at a "Cautionary risk" level, with urban children suffered the highest risk. Petroleum pollution, Coal and biomass combustion, and Marine transport emissions were identified as the main anthropogenic sources for PAHs in organisms, and Marine transport emissions accounted for the highest Carcinogenic risk. The Acceptable daily intake for all populations were far below their actual daily intake without causing "Cautionary risk". Our findings provide new insights into the source apportionment and health risk of PAHs from a "source-organism-human" perspective, and suggested that joint management of three anthropogenic sources would be an effective way to prevent the health risks of PAHs.

Polycyclic aromatic hydrocarbons in coral reefs with a focus on Scleractinian corals: A systematic overview

The impact of petroleum exploitation and oil spills in marine ecosystems has increased over time. Among the concerns regarding these events, the impact on coral reefs stand out because this ecosystem has ecological and economic importance and is globally threatened. We performed a systematic review and bibliometric analysis of studies that determine polycyclic aromatic hydrocarbons (PAHs) in coral reefs, attempting to answer how the studies were distributed around the globe, the main environmental matrices and species of coral studied, the main PAHs found and their mean concentrations, and the methodology used. A bibliographic search resulted in 42 studies with worldwide distribution. The bibliometric results presented more explored terms, such as sediments and toxicology, and newly investigated terms, which should encourage a new area of study, such as those related to zooxanthellae and mucus. The main matrices studied in coral reefs are sediments, corals, and water, whereas air and other invertebrates have rarely been studied. Approximately 45 species of corals with several morphotypes have been reported. PAHs recommended by the United States Environmental Protection Agency (US EPA) were analyzed in all studies, while additional compounds were analyzed in only five. The methods used to determine hydrocarbons are predominantly the most traditional; however, for corals, studies have tended to separate tissue, zooxanthellae, skeleton, and mucus. In the future, we recommend investment in improving the capacity to detect non-conventional PAHs, more studies in regions that are rarely explored in developing countries, and the creation of databases to facilitate management planning on marine coasts.

Environmental profile, potential sources, and ecological risk of polycyclic aromatic hydrocarbons in a typical coastal bay and outer bay area

As a class of persistent organic pollutants, polycyclic aromatic hydrocarbons (PAHs) are widely present and accumulate in multimedia environments. The pollution characteristics, spatiotemporal distribution, potential sources, influencing factors, and ecological risks of 16 PAHs were investigated in the water-sediment system of the Hangzhou Bay and outer bay area (HZB and OBA, respectively). The total concentrations of 16 PAHs (∑_PAHs) were 220 ± 97.0 and 130 ± 36.0 ng/L in the seawater and 343 ± 179 and 505 ± 415 μg/kg (dry weight) in the sediments of the HZB and OBA, respectively. The pollution level of PAHs in the HZB seawater was higher than that in the OBA seawater, but the opposite result was found in the sediments. Moreover, ∑_PAHs exhibited high temporal variability in the HZB seawater (rainy season > dry season), whereas ∑_PAHs in the sediments showed no significant difference between seasons. The molecular diagnostic ratio method was used to identify pollution sources and showed that the PAHs in seawater came from different pollution sources (fuel combustion and petroleum), whereas the PAHs in the sediments originated from coincident sources (mixed combustion). Correlation analysis revealed that temperature was positively related to ∑_PAHs, whereas salinity was negatively related to seawater ∑_PAHs values. Ecological risk assessment demonstrated that the potential for adverse ecological effects was low to moderate in seawater but moderate to high in the sediments.

Evaluation of polycyclic aromatic hydrocarbons in sediments of Balsas River Mouth, Pacific Coast, Mexico: Sources, risks, and genotoxicity

Polycyclic aromatic hydrocarbons (PAHs) were assessed in sediments (n = 7) collected from the mouth of the Balsas River, Pacific Coast, Mexico. The total PAH levels ranged between 142.1 and 3944.07 μg kg^-1 in the summer and 137.65-3967.38 μg kg^-1 in the winter, probably reflecting the anthropogenic activities of the region. Calculation of the four analytical ratios of [Anthracene/(Anthracene + Phenanthrene)]: [Fluoranthene/(Fluoranthene + Pyrene)], [Fluoranthene/Pyrene: Fluoranthene/(Fluoranthene + Pyrene)], [Indeno [123-cd]Pyrene/(Indeno [123-cd]Pyrene + Benzo [ghi]Perylene)]: [Benzo [a]anthracene/(Benzo [a]Anthracene + Chrysene)], and [Anthracene/Phenanthrene]: [Fluoranthene/(Fluoranthene + Pyrene)] revealed a mixed PAH source, from petroleum and biomass combustion. Significant statistical correlations (r² = 0.90) between the 4 and 5 ringed PAHs denote that adsorption is the principal mechanism for accumulation in sedimentary archives. Ecotoxicological indices (Mean Effect Range Medium Quotient and Mean Probable Effect Level Quotient) indicated moderate pollution with adverse biological impacts on ambient benthonic organisms. The calculations of Toxicity Equivalent Quotient and Mutagen Equivalent Quotient values proposed that the region is highly polluted by mutagenic and carcinogenic PAH compounds. The genotoxic evaluation of Lutjanus guttatus (Spotted rose snapper) presented significant DNA damage and discrepancies in Ethoxyresorufin-O-Deethylase activity. Based on the toxicological and genotoxicological evaluation of PAHs in sediments, the region was observed to be largely impacted from biological damage.

Polycyclic aromatic hydrocarbons in a Natural Heritage Estuary influenced by anthropogenic activities in the South Atlantic: Integrating multiple source apportionment approaches

Polycyclic aromatic hydrocarbons (PAHs) were analysed in the sediments of one of the most well-preserved estuaries in South Brazil, the Paranaguá Estuarine System (PES), using several source apportionment tools. The ∑PAH ranged from < DL to 125.6 ng g^-1 dw (dry weight) (average 29.9 ± 26.1 ng g^-1 dw), and the lowest levels detected were similar to those found in other protected areas of the world. In general, the PAH concentrations indicated excellent environmental quality for the entire estuary. Principal component analysis indicated that fine sediments and total organic carbon were the main factors controlling PAH concentrations in the PES. Multiple PAH sources were identified in the study area; biomass burning and fossil fuel combustion predominated but considerable amounts of petrogenic residues were also observed. We identified evidence of a contribution from an adjacent watershed resulting from the construction of interconnections between large rivers and from years of intense deforestation in the local Atlantic Forest.

Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Seawater and Sediments, Human and Ecological Risks, Northern Coastline of Persian Gulf

This study aimed to assess 13 PAHs concentrations and induced human and ecological risks in seawater and surficial sediments of eight estuaries in the northern coastline of the Persian Gulf, Iran, 2021. The range of Σ13 PAHs concentration was 0.24-8.83 µg L^-l and 3.1-11.46 µg g^-1 dry weight, and the mean value was 4.99 µg L^-l and 6.06 µg g^-1 dry weight in seawater and sediment, respectively. Two, three and four rings PAHs were dominant with 29.33% and 41.33% of ΣPAHs in seawater and sediment, respectively. The primary source of PAHs was both pyrolytic and petrogenic. Most PAHs' calculated health (DCR, HQs, TEF, MEF) and ecological risks (SQGs) values in seawater were in the moderate range or high-risk values for damage to the marine environment. It is concluded that the pollution of PAHs should be carefully considered, and the government should make a proper action plan to minimize the pollution.

Environmental fate and effects of PAHs in tropical mariculture ponds near the northern South China Sea: Rainfall plays a key role

The behavior and fate of PAHs are affected by multiple meteorological factors, but the main factors driving PAHs in tropical mariculture areas are still not clearly understood. This study continuously monitored PAHs in a few tropical land-based mariculture ponds, discussed their dynamic change trend, migration among the multiple media, and the relevant affected factors. Results indicated that PAHs were widely distributed in these environmental media, and the PAHs' concentration showed an obvious attenuation trend in the mariculture cycle. Wet deposition brought overwhelming majority atmospheric PAHs (92 % ± 5.7 %) to the aqueous system, and >72 % of these PAHs came from oil combustion-related sources and biomass combustion. Compared with the natural sea areas in the same region, mariculture ponds sediment could be changed from a sink at the early stage to a secondary release source of PAHs at the late stage of the rainy season, which intensifies the bioaccumulation of PAHs and the risk of edible carcinogenesis of aquatic products. Our research revealed that rainfall drove the occurrence and environmental behavior of PAHs in the tropical mariculture areas, while land-based mariculture ponds ecosystem affected the regional environmental fate of PAHs and weakened their transmission to the marine environment from land.

Environmental DNA-based profiling of benthic bacterial and eukaryote communities along a crude oil spill gradient in a coral reef in the Persian Gulf

Coral reef ecosystems in the Persian Gulf are frequently exposed to crude oil spills. We investigated benthic bacterial and eukaryote community structures at such coral reef sites subjected to different degrees of polycyclic aromatic hydrocarbon (PAH) pollution using environmental DNA (eDNA) metabarcoding. Both bacterial and eukaryote communities responded with pronounced shifts to crude oil pollution and distinguished control sites, moderately and heavily impacted sites with significant confidentiality. The observed community patterns were predominantly driven by Alphaproteobacteria and metazoans. Among these, we identified individual genera that were previously linked to oil spill stress, but also taxa, for which a link to hydrocarbon still remains to be established. Considering the lack of an early-warning system for the environmental status of coral reef ecosystems exposed to frequent crude-oil spills, our results encourage further research towards the development of an eDNA-based biomonitoring tool that exploits benthic bacterial and eukaryote communities as bioindicators.

Distribution, source and ecological risk assessment of polycyclic aromatic hydrocarbons in the sediments of northern part of the Persian Gulf

Distribution, sources, and ecological risk of 43 compounds of polycyclic aromatic hydrocarbons (PAHs) in surficial sediments of the Persian Gulf were investigated. The sediments were sampled from 60 offshore stations during an oceanographic cruise in the winter of 2012. Gas chromatography high-resolution mass spectrometry was used for the PAHs determinations in sediment samples. The concentrations of 21 parent PAHs, 7 methylated PAHs, 11 oxygenated PAHs and 4 nitrated PAHs were 9.0-201.5 ng g^-1 dw, 3.3-60.3 ng g^-1 dw, 15.2-172.7 ng g^-1 dw and 0.1-8.3 ng g^-1 dw, respectively. Among 21 parental PAHs, naphthalene (29.35 ng g^-1 dw), phenanthrene (4.6 ng g^-1 dw), and pyrene (3.18 ng g^-1 dw) were the most abundant compound. 1-acenaphthenone (43.41 ng g^-1 dw) and 2-methylnaphthalene (7.15 ng g^-1 dw) showed the highest concentration in the oxy- and methyl-PAHs, respectively. The concentrations of nitro-PAHs were between not detected to 4 ng g^-1 dw. According to the ecological risk assessment, the calculated total toxicity of PAHs was at below the lethal level on benthic organisms in all stations in the Persian Gulf, but there is risk of toxicity for the benthic organism in the Gulf of Oman (from the Strait of Hormuz to Jask). In general, nitrogenated and oxygenated derivatives did not show a significant risk in the study area. Based on the diagnostic ratios, the mixed sources (both petrogenic and pyrogenic) and pyrogenic sources have been identified for PAHs. Biomass combustion source has been identified for the stations near flares and gas fields. Principle component analysis-multivariate linear regression analysis for source identification shows that maritime traffic, abundant flares that burn the gas in oil, gas fields and dust storms have a major impact on the production of PAHs in this area.

Integration of chemical and biological methods: A case study of polycyclic aromatic hydrocarbons pollution monitoring in Shandong Peninsula, China

Polycyclic aromatic hydrocarbons (PAHs), as persistent toxic substances (PTS), have been widely monitored in coastal environment, including seawater and sediment. However, scientific monitoring methods, like ecological risk assessment and integrated biomarker response, still need massive researches to verify their availabilities. This study was performed in March, May, August and October of 2018 at eight sites, Yellow River estuary (S1), Guangli Port (S2), Xiaying (S3), Laizhou (S4), Inner Bay (S5), Outer Bay (S6), Hongdao (S7) and Hongshiya (S8) of Shandong Peninsula, China. The contents of 16 priority PAHs in local seawater and sediment were determined, by which ecological risk assessment risk quotient (RQ) for seawater and sediment quality guidelines (SQGs) were calculated to characterize the PAHs pollution. Meanwhile, multiple biomarkers in the digestive gland of clam Ruditapes philippinarum were measured to represent different biological endpoints, including ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), sulfotransferase (SULT), superoxide dismutase (SOD) and lipid peroxidation (LPO), by which integrated biomarker response (IBR) was calculated to provide a comprehensive assessment of environmental quality. Taken together, these results revealed the heaviest pollution at S2 as both PAHs concentrations and biomarkers responses reflected, and supported the integrated biomarker response as a useful tool for marine environmental monitoring, through its integration with SQGs.

Low levels of persistent organic pollutants in sediments of the Doce River mouth, South Atlantic, before the Fundão dam failure

The Doce River mouth (DRM) was severely impacted by the rupture of the Fundão Dam in 2015, considered the greatest Brazilian environmental tragedy in terms of tailings volume released (>40 million m³) and traveled distance (~600 km until the Atlantic Ocean). Environmental monitoring has been performed since then, but background levels are scarce or absent to Persistent Organic Pollutants (POPs), making impact assessments difficult. In the current study, we presented the baseline levels, inventories, and risk assessment of the POPs polychlorinated biphenyl (PCBs) and organochlorinated pesticides (OCPs), in surface sediment of the DRM. Samples were collected in December 2010 and July 2011, i.e., four years before the Fundão dam failure. The total PCBs and the OCPs (Aldrin, HCHs, and Chlordanes) were detected in both sampling campaigns, with levels up to 9.50 and 1.64, 0.28, and 0.63 ng g^-1, respectively. The decrease of the Doce River flow was the main factor contributing to seasonal variations in the spatial distribution, and to a slight decline in the levels and frequency of the analyzed POPs in sediments collected in the dry season (July 2011). Environmental risk assessment, inventories, and total mass results suggest a low potential of PCBs and OCPs accumulation before the dam failure. This is the first POPs assessment in the study area that helped identify some unexpected impacts of the Fundão dam failure and contributed to the understanding of POPs cycles in the Southern Atlantic, data that are still scarce in the region.

Distribution, sources, and ecological risk assessment of polycyclic aromatic hydrocarbons (PAHs) in the tidal creek water of coastal tidal flats in the Yellow River Delta, China

The concentrations, distribution, sources and ecological risk levels of polycyclic aromatic hydrocarbons (PAHs) in tidal creek water from coastal tidal flats of the Yellow River Delta were investigated. The concentrations of 16 PAHs ranged from 0.113 to 1.533, with a mean value of 0.496 ± 0.035 μg L^-1, which indicated a moderate level of pollution. The main long-term sources of PAHs in the coastal tidal flats of the Yellow River Delta were petroleum combustion and petroleum pollution. The ecological risk assessment showed that the levels of PAHs in tidal creek water of the coastal tidal flats in the Yellow River Delta corresponded to medium to high ecological risk levels, and a high probability of potential ecological risk, posing harm to aquatic organisms. Among the 7 sampling sites, site 5, site 6, and site 7 were at high ecological risk, and the other sites were at moderate ecological risk. PAH pollution in the tidal creek water near the Yellow River Estuary and farther south, in the coastal tidal wetland of Laizhou Bay, deserves special attention, especially with respect to the prevention and control of benzo[a]pyrene (BaP) pollution in the water.

Spatiotemporal occurrence, sources and risk assessment of polycyclic aromatic hydrocarbons in a typical mariculture ecosystem

The spatiotemporal variations, influencing factors and potential sources, as well as the ecological/health risks of polycyclic aromatic hydrocarbons (PAHs) were systematically investigated in seawater, sediment, and fish from Xiangshan Bay, China, one of the most important and oldest domestic marine aquaculture bases. The average concentrations of Σ_PAHs in seawater, sediment and fish were 150 ± 70.0 ng/L, 276 ± 271 μg/kg (dry weight, dw), and 434 ± 151 μg/kg (dw), respectively. Naphthalene, phenanthrene, fluoranthene, benzo(b)fluoranthene and pyrene were the dominant contaminants in all samples. The highest PAH concentrations in the seawater and sediment samples occurred in the inner bay where the mariculture and industry are clustered. Seasonal differences were observed in the seawater samples but not in the sediment samples. Among all 15 fish species, large yellow croaker (Larimichthys crocea) (775 μg/kg (dw)), red drum (Sciaenops ocellatus) (749 μg/kg (dw)), and flathead grey mullet (Mugil cephalus) (637 μg/kg (dw)) had relatively high PAH accumulation concentrations in muscle tissue. According to the molecular diagnostic ratio method, the PAHs in seawater mainly originated from a mixed source of petroleum and combustion, whereas biomass/coal combustion sources were identified for sediment. The results obtained from the risk quotient (for seawater), sediment quality guidelines and toxic equivalence quotients (for seawater and sediment) methods showed that the ecological risks posed by PAHs were generally at a low to moderate level. Potentially toxic effects existed from PAH-contaminated fish consumption, and the resulting potential carcinogenic risk was also slightly higher than the recommended guidelines (10^-6).

A potential threat to the coral reef environments: Polybrominated diphenyl ethers and phthalate esters in the corals and their ambient environment (Persian Gulf, Iran)

Pollution of the surrounding habitat poses one of the biggest threats to the coral health and even survival. This study focuses on the occurrence, distribution, bioaccumulation and bioconcentration of polybrominated diphenyl ethers (PBDEs) and phthalate esters (PAEs) in corals, their zooxanthellae and mucus, as well as in their ambient environment in Larak coral reef (Persian Gulf) for the first time. The highest concentrations of the pollutants were recorded in mucus, followed by zooxanthellae, tissue and skeleton. Soft corals with higher lipid content contained more PBDEs and PAEs. Pollutants were both efficiently bioconcentrated from water and bioaccumulated from the ambient sediment, albeit bioconcentration played the most prominent role. Elevated PBDEs and especially PAEs concentrations were detected in the skeletons of the bleached corals if compared to the skeleton samples of the non-bleached individuals.

Multiple benthic indicators are efficient for health assessment of coral reefs subjected to petroleum hydrocarbons contamination: A case study in the Persian Gulf

The ever-increasing anthropogenic activities have adversely impacted coral reef ecosystems and their ecological functions. This calls for an urgent assessment of the health state of these valuable ecosystems to justify the need for mitigation and proper management efforts. In this contribution, we used multiple indicators to assess the impact of intense oil-related activities on coral reefs in two near-by impacted and non-impacted islands in the northwestern Persian Gulf. The efficacy of indices was assessed using estimations of the effect size (omega-squared), precision, and decision trees (Classification and Regression Tree (CART)). The results demonstrated that the combination of bioaccumulation of ƩPAH in coral tissues, the percent of live coral cover, and the Sediment Constituent (SEDCON) Index were the most robust proxies reflecting the influence of human activities on reef's health. Based on sedimentary PAH concentration, the CART classified most of the indicators into two classes consisting of those in impacted and those in non-impacted locations, further supporting the feasibility of the employed indices. The findings of this study provided a warning of degradation in coral reefs of the island subjected to PAH pollution. This encourages decision-makers to execute routine monitoring and mitigation practices to maintain healthy reefs in the study areas.

Chlorinated paraffins (SCCPs and MCCPs) in corals and water-SPM-sediment system in the Persian Gulf, Iran: A potential global threat for coral reefs

Swift degradation of the coral reef ecosystems urges the need to identify the reef decline drivers. Due to their widespread use, bioaccumulative and toxic characteristics, chlorinated organic compounds, such as chlorinated paraffins (CPs), are regarded as specific pollutants of concern. Yet little is known about the occurrence of CPs in the coral reef ecosystems. This study focuses on the short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs). Their distribution and congener pattern were investigated in the water-SPM-sediment system and in the corals of the Larak coral reef for the first time. Chlorinated paraffins were detected in all the coral species. Their total loadings ranged from 42.1 to 178 ng g^-1 dw in coral tissue, from 6.0 to 144 ng g^-1dw in the skeleton, and from 55.0 to 240 ng g^-1dw in zooxanthellae. Soft corals were found to accumulate more CPs than Scleractinian corals. Zooxanthellae and mucus accumulated more CPs than tissue and skeleton. In most cases, congener group patterns were dominated by C₁₃ (for SCCPs) and C₁₇ (MCCPs) groups, respectively. The congener patterns of CPs altered to some extent between mucus and the remaining coral compartments. High loadings of CPs were detected in the skeleton of the bleached corals. Moreover, a significant negative correlation between the levels of CPs and the symbiodinium density was observed.

Emerging POPs-type cocktail signatures in Pusa caspica in quantitative structure-activity relationship of Caspian Sea

The Caspian seal Pusa caspica is the only endemic mammalian species throughout the Caspian Sea. This is the first report on risk assessment of persistent organic pollutants (POPs) in Caspian seals by age-sex and tissue-specific uptake, and their surrounding environment (seawater, surface sediments, and suspended particulate matters, SPMs) in the Gorgan Bay (Caspian Sea, Iran). Among the quantified 70 POPs (∑₃₅PCBs, ∑₃HCHs, ∑₆CHLs, ∑₆DDTs, ∑₁₇PCDD/Fs, HCB, dieldrin, and aldrin), ∑₃₅PCBs were dominant in abiotic matrices (48.80% of ∑₇₀POPs), followed by HCHs > CHLs > DDTs > PCDD/Fs > other POPs in surface sediments > SPMs > seawater, while the toxic equivalent quantity (TEQ_WHO) exceeded the safe value (possible risk in this area). In biota, the highest levels of ∑₇₀POPs were found in males (756.3 ng g^-1 dw, p < 0.05), followed by females (419.0 ng g^-1 dw) and pups (¹91.6 ng g^-1 dw) in liver > kidney > muscle > blubber > intestine > fur > heart > spleen > brain. The positive age-related POPs declining correlation between mother-pup pairs suggested the possible maternal transfer of POPs to offspring. The cocktail toxicity assessment revealed that Caspian seals can pose a low risk based on their mixed-TEQ values. Self-organizing map (SOM) indicated the non-coplanar PCB-93 as the most over-represented functional congener in tissue-specific POPs bioaccumulation. Quantitative toxicant tissue-profiling is valuable for predicting the state of mixture toxicity in pinniped species.

Occurrence, distribution and pollution pattern of legacy and emerging organic pollutants in surface water of the Kongsfjorden (Svalbard, Norway): Environmental contamination, seasonal trend and climate change

This work aimed to investigate the contamination pattern in Kongsfjorden marine environment (Svalbard, 79°N 12°E) and to disentangle primary and secondary emissions. Surface seawater, sampled in two seasons, was analysed by GC-MS and LC-MS/MS to detect polychlorobiphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), nonylphenols (NPs), bisphenol A (BPA) and perfluoroalkyl and polyfluoroalkyl substances (PFASs). In summer, average ΣPAHs, BPA, ΣNPs, ΣPFASs and ΣPCBs concentrations were 17.3 ± 11.1 ng/L, 0.9 ± 0.3 ng/L, 10.0 ± 6.9 ng/L, 0.4 ± 0.7 ng/L and 1.8 ± 1.3 pg/L, respectively; while in winter, they were 13.6 ± 10.1 ng/L, 0.5 ± 0.2 ng/L, 6.8 ± 3.3 ng/L, <LOD and 0.6 ± 0.4 pg/L, respectively. The application of generalized linear models (GLMs) highlighted that: PFAS pattern agrees their predominant long-range hydrospheric transport; the additive effect of the distance to glacier and harbour affected PAH, NP and BPA distributions; the additive effect of season and distance from the glacier, but not their interaction, influenced PCBs distribution, indicating melting glaciers as potential secondary POP sources.

Large-scale evaluation of deposition, bioavailability and ecological risks of the potentially toxic metals in the sediment cores of the hotspot coral reef ecosystems (Persian Gulf, Iran)

Coral reefs of the Persian Gulf are vulnerable to the potentially toxic metals (PTMs) accumulated in the ambient sediments. Nonetheless, few studies have investigated the PTMs pollution and risk in the hotspot coral ecosystems of the Persian Gulf at a large-scale. Hereupon, this study focused on the PTMs contamination, their potential ecological risks, historical depositions, geochemical controls and the plausible pollution sources in the core sediments (0-40 cm) collected from the ten coral ecosystems of the Persian Gulf, Iran. Both total and fraction analysis indicated considerable metal pollution levels. Contamination was steadily decreasing towards the bottom of the sediment core, revealing the impact of a recent anthropogenic input. High metal association with the exchangeable and other mobile fractions was observed, indicating their high bioavailability. Of all the elements analyzed, toxic metals Cd, Hg and As exhibited the highest potential ecological risk (RI). Site rank index (SRI), modified degree of contamination (_mCd), and contamination severity index (CSI) based approaches identified stations ST5, ST9 and ST10 as the most contaminated sites of the study area. The same stations were also found to possess considerable ecological risk. Principal component analysis (PCA) revealed that the stations located in the zone of the highest anthropogenic impact contain pollution sources for all the metals analyzed, whereas areas with low anthropogenic activity are mainly affected by the river runoff and urban emissions.

Biomonitoring of perylene in symbiotic reef and non-reef building corals and species-specific responses in the Kharg and Larak coral reefs (Persian Gulf, Iran): Bioaccumulation and source identification

In this study, coral soft tissue, skeleton and zooxanthellae, as well as their ambient sediment and seawater were analyzed for polycyclic aromatic hydrocarbons (PAHs) with a special focus on perylene. Samples were collected from two different environments: the Kharg Island, which is affected by numerous anthropogenic stressors and Larak Island, which is mainly used for recreational and fishing activities and is characterized by dense vegetation. The heaviest loadings of PAHs were observed on Kharg Island, yet higher concentrations of perylene were detected on Larak Island and it was identified as the prevailing compound in this area. Pyrogenic perylene sources were prevailing on Kharg Island, whereas the perylene on Larak Island was determined to be of natural origin. After analyzing the biological samples, higher perylene concentrations were observed in zooxanthellae than in tissue and skeleton. The lowest and the highest perylene loadings were found in the tissue and skeleton of Platygyra daedalea and Porites lutea, respectively. This applies to both reefs. We found that perylene distribution in the corals and their ambient environment follows an irregular pattern, demonstrating remarkable effects from the local inputs. The lipid content in the coral tissue and the location of the coral colony were deduced to be the main factors affecting perylene distribution in corals. On Larak Island, a significant correlation between perylene loadings in sediment and corals was observed. On Kharg Island, a strong interaction between the water column and the corals was detected. The symbiotic relationship between the corals and zooxanthellae might play the most significant role in bioconcentration and bioaccumulation of perylene. Due to the insolubility of PAHs, they could be transferred through a food chain to zooxanthellae and eventually deposited in the coral bodies.

Comparative study of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) in corals, sediments and seawater from coral reefs of Hainan, China

This work investigated levels of PAHs and HMs in fourteen species from seven genera of scleractinian corals, adjacent sediments, and surface seawater in Hainan, China. The sources of contaminations were analyzed as well. The results showed that scleractinian corals had a relatively higher bioaccumulation capacity for PAHs from sediments than for HMs. There were inter-species differences for these contaminants enriched in corals. Pavona varians and Porites lutea could accumulate PAHs more readily. While higher concentrations of Cr, Mn and Pb occurred in Favites flexuosa, other metal levels, such as for Ni, Cu, Zn and As, were found to be elevated in Pocillopora damicornis, as well as for Cd in Acropora echinata. It was found that PAHs originated from petrogenic and pyrolytic sources, and were mainly linked to onshore and on-sea activities, such as motorboats. Mn, Ni, As and Cd were from crustal materials or natural weathering, while Cr, Cu, Zn and Pb were non-crustal origin connecting with the use of anti-fouling boat paint and agricultural and/or aquacultural chemicals. This study suggested that corals could serve as good bioindicators for two types of chemical pollution in the reef system, especially for the two species P. varians and P. lutea for PAHs contaminants.

Why do mesophotic coral ecosystems have to be protected?

Mesophotic coral ecosystems (MCEs; ~30-150 m depth) are among the most biologically diverse and least protected ecosystems in the world's oceans. However, discussions regarding the conservation of these unique ecosystems are scarce. To address this issue, we identified the features of MCEs that demonstrate they should be considered as a global conservation priority. Some MCEs are characterized by their well-preserved and unique seascapes; their narrow environmental tolerance and high vulnerability to anthropogenic effects; and their slow recovery and reduced reproductive performance. The unique biodiversity of MCEs includes depth-adapted specialist species and new species, most of which are threatened or important fishery resources. MCEs also provide refuge against human stressors, valuable ecosystem services, and ecological connectivity. MCEs generally meet the criteria to be classified as Ecologically and Biologically Significant Marine Areas under the Convention on Biological Diversity. However, we highlight that many MCEs worldwide are threatened and not yet adequately protected by fishery regulations, marine protected areas, or considered in marine spatial planning. Establishing MCEs as a global conservation priority requires the designation of national, international, transnational, public, and private policies.

First report on polybrominated diphenyl ethers in the Iranian Coral Islands: Concentrations, profiles, source apportionment, and ecological risk assessment

Coral reefs are challenged by multiple stressors due to the growing industrialization. Despite that, data on their environment are still scarce, and no research is yet performed on polybrominated diphenyl ethers in the Persian Gulf area. Seeking to fill in this gap, the present study aims to determine spatio-vertical distributions, source apportionment and ecological risk of polybrominated diphenyl ethers in the sediment cores and seawater samples from ten coral reef Islands in the Persian Gulf, Iran. Σ₁₂PBDEs concentrations ranged from 0.42 ± 0.04 to 47.14 ± 1.35 ng g^-1 dw in sediments, and from 1.17 ± 0.06 to 7.21 ± 1.13 ng L^-1 in seawater. The vertical polybrominated diphenyl ethers distribution varied significantly among the sampling stations and different depths with a decreasing trend towards the surface and peaks around 12-20 cm. Both in the seawater and sediment samples, elevated polybrominated diphenyl ethers loadings were observed in highly industrialized areas. Deca-bromodiphenyl ether-209 was the predominant congener along the sediment cores, whereas Tetra-bromodiphenyl ether-47 and Penta-bromodiphenyl ether-100 dominated in seawater samples. Commercial Deca-bromodiphenyl ether mixture was found to be the major source of polybrominated diphenyl ethers. Penta-bromodiphenyl ether was revealed to be the major ecological risk driver in the study area: it posed medium to high-risk quotient to sediment dwelling organisms. This study indicated that coral reefs are playing an important role in retaining polybrominated diphenyl ethers and highlighted the need to manage polybrominated diphenyl ethers contamination in the coral reef environment.

Historical sedimentary deposition and flux of PAHs, PCBs and DDTs in sediment cores from the western Adriatic Sea

The sources and depositional history of polycyclic aromatic hydrocarbons (PAHs) and organochlorine compounds (OCs) over the last century were investigated in sediment cores from the North Adriatic Sea (Po River prodelta) and the South-Western Adriatic Margin (SWAM). Contaminant concentrations were higher in the Po River prodelta. ∑₁₆PAHs ranged from 193 to 533 ng g^-1, ∑₅PCBs ranged from 0.9 to 5.2 ng g^-1 and ∑DDTs (p,p'-DDD + p,p'-DDE) ranged from 0.1 to 2.5 ng g^-1. In the SWAM, ∑PAHs ranged from 11 to 74 ng g^-1 while ∑PCB and ∑DDT concentrations were close to the MQL. Accordingly, contaminant fluxes were much higher in the northern (mean values of 152 ± 31 ng cm² y^-1 and 0.70 ± 0.35 ng cm² y^-1 for PAHs and OCs, respectively) than in the southern Adriatic (2.62 ± 0.9 ng cm² y^-1 and 0.03 ± 0.02 ng cm² y^-1 for PAHs and OCs, respectively). The historical deposition of PAHs seemed to be influenced by the historical socioeconomic development and by changes in the composition of fossil fuel consumption (from petroleum derivatives to natural gas) in Italy from the end of the 19th century to the present. Similarly, vertical variations in DDT concentrations matched its historical use and consumption in Italy, which started around in the mid-late 1940s to fight typhus during the II World War. Contaminant concentrations detected in sediments does not seem to pose ecotoxicological risk for marine organisms in the Adriatic Sea.

Historical sedimentary deposition and ecotoxicological impact of aromatic biomarkers in sediment cores from ten coral reefs of the Persian Gulf, Iran

The present study determines the levels, vertical distributions, source apportionment and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in ten sediment cores of coral reef in the Persian Gulf, Iran, one of the important oil polluted marine areas in the world. The main purpose of this study was to determine the spatio-vertical distribution pattern of PAHs pollution at the four hot spot zones on the Gulf: dense industrial, medium industrial, urbanized and non-impacted zones over the past few years. Sediment quality and ecological risk were also assessed in order to determine the pollutants of concern. In detail, 23 parent (PPAHs) and 16 alkylated PAHs (APAHs), along with retene and perylene, were determined in sediment cores (0-40 cm depth). The vertical distribution of all PAHs showed a wide variation among sampling stations and depths, with a decreasing trend of concentration from surface to bottom, and a peak at 12 cm. Total concentrations of PPAHs and APAHs ranged from 35 to 1927 ng g^-1 dw and 19 to 1794 ng g^-1 dw respectively, with the highest concentrations at the industrial zone. The diagnostic ratio for PAHs and perylene (3 to 1277 ng g^-1 dw) indicated mixed sources of PAHs, with dominance of petrogenic origins at the industrial zone and natural diagenetic inputs, respectively. The PAH concentration depicted a significant decreasing trend along the length of the core with an abrupt increase within the core length 12-20 cm. Temporal variations in contaminants can be linked to economic, coastal developments and industrial growth. Overall, the baseline data on geographical distribution, congener profiles, sources and vertical deposition of PAHs in the Persian Gulf area would be useful to establish proper monitoring plans for this sensitive ecosystem.

Forage fish and polycyclic aromatic compounds in the Fort McMurray oil sands area: Body burden comparisons with environmental distributions and consumption guidelines

The Fort McMurray region in northeastern Alberta (Canada) is rich in natural sources of polycyclic aromatic compounds (PACs) from exposed bitumen beds; anthropogenic sources are being released with increased oil sands industry expansion. Here we report on investigations of PACs (47 compounds) in three species of forage fish collected during the 2012-2013 Joint Oil Sands Monitoring Program (JOSMP) fish health investigations and compare results with PAC data for sediment and water collected under JOSMP and earlier programs. PAC concentrations in sediments varied three orders in magnitude and were highest at downstream tributary mouths, which flowed through the exposed McMurray Formation, and along reaches of the Athabasca River where the formation was exposed. PAC concentrations in water were less variable but with higher concentrations near exposed bitumen beds. Forage fish exhibited the weakest spatial gradients in ΣPACs concentration, which averaged 102 ± 32 ng/g in trout-perch from the Athabasca River, 125 ± 22 ng/g in lake chub from the Ells River, and 278 ± 267 ng/g in slimy sculpin from the Steepbank, Firebag, and Dunkirk Rivers. Low-molecular weight compounds, particularly naphthalenes and fluorenes, dominated fish PACs. Phenanthrenes occurred in greater percent composition in fish caught in areas where PAC concentrations in sediments were higher due to the proximity of bitumen sources than in other areas. Dibenzothiophene, a major component of bitumen PAC, was a minor component of fish ΣPACs. Forage fish PAC concentrations were below fish consumption guidelines established by the European Commission (2011) and for the reopening of the commercial fisheries closed by the Deepwater Horizon oil spill. PAC concentrations in forage fish were similar to concentrations observed in many other studies (fish market surveys, estuaries, and marine waters) and lower than in fish sampled from highly impacted areas (near refineries, harbors, and other industrialized areas).

First polychlorinated biphenyls (PCBs) monitoring in seawater, surface sediments and marine fish communities of the Persian Gulf: Distribution, levels, congener profile and health risk assessment

Polychlorinated biphenyls (PCBs) are persistent organic pollutants that, due to their high toxicity, lipophilic property and widespread dispersal in the global environment, present a danger for human health and ecological systems. Although the inventory and use of PCBs are extensively reported worldwide, the status of PCBs in Iran is still unknown. In this study, the concentrations of PCBs were determined in the environmental matrices and in five commercially important fish species from Larak coral Island, Persian Gulf, Iran, in winter and summer 2015. A positive correlation was found among PCBs levels and congeners profiles in seawater (0.97-3.10 ng L^-1), surface sediments (2.95-7.95 ng g^-1dw) and fish samples (7.20-90.19 ng g^-1dw), indicating fish as suitable bioindicator of environmental PCBs contamination. In all matrices, a high contribution of light and medium chlorinated congeners was detected in both seasons. In fish, the higher PCBs levels were found for both sexes in both seasons in liver and kidney than other tissues (skin, gonad, muscle) due to their high lipid content and PCBs lipophilicity. More importantly, the risks for human health associated with fish consumption were also evaluated, and it was found that all the toxicity indices measured for PCBs were within the World Health Organization (WHO) permissible limit of food consumption. However, it is highly recommended to inform the local population about potential risks attributable to dietary incorporation of locally caught fish, and establish a surveillance monitoring programme on PCBs in this region.

Quantitative evaluation of n-alkanes, PAHs, and petroleum biomarker accumulation in beach-stranded tar balls and coastal surface sediments in the Bushehr Province, Persian Gulf (Iran)

Coastal areas within the Bushehr Province (BP), Persian Gulf, Iran, face great challenges due to the heavy organic contamination caused by rapid industrialization, and the presence of numerous oil fields. In addition, in 2014, a significant number of tar balls are found along the coasts of BP. A total of 96 samples (48 coastal sediments and 48 tar balls) were taken from eight sampling points at the BP coast during the summer of 2014. These samples were analyzed to identify the sources and characteristics of their organic matter using diagnostic ratios and fingerprint analysis based on the distribution of the source-specific biomarkers of n-alkanes, PAHs,¹ hopanes and steranes. Mean concentration of n-alkanes (μg g^-1 dw) and PAHs (ng g^-1 dw) varied respectively from 405 to 220,626, and 267 to 23,568 in coastal sediments, while ranged respectively from 664 to 145,285 and 390 to 46,426 in tar balls. In addition, mean concentration of hopanes and steranes (ng g^-1 dw) were between 18.17 and 3349 and 184.66 to 1578 in coastal sediments, whereas in tar balls were 235-1899 and 520-1504, respectively. Pri/Phy² ratio was 0.25 to 1.51 (0.65) and 0.36 to 1 (0.63) in coastal sediment and tar ball samples, respectively, and the occurrence of UCM³ in both matrices, reflecting the petrogenic OM⁴ inputs and chronic oil contamination, respectively. The C₃₀ and C₂₉ homologues followed Gammacerane were detected in both matrices, in particular those collected from intensive industrial activities, suggesting petrogenic sources of OM. The coastal sediment PAHs profiles were significantly dominated by HMW⁵-PAHs in the Bahregan Beach (BAB) (78% of total PAHs), Bandare-Genaveh (GP) (66%), and Bandare-Bushehr (BUB) (61%) stations, while the Bashi Beach (BSB) (40%), Bandare-Kangan (KP) (57%), and Bandare-Asaluyeh (AP) (51%) stations exhibited higher proportion of LMW⁶-PAHs. PCA⁷ indicated that the tar ball and coastal sediment samples deposited along the Southwest of the BP beaches are most likely originated from the Abuzar oil. Based on the intensity of the anthropogenic activities, NPMDS⁸ analysis revealed that the GP, BAB, NNP, AP, and KP sampling sites had a high concentration of detected organic pollutants. To the best of our knowledge, this is the first study that investigates oil pollution in costal sediments and tar balls in the BP, providing insights in to the fate of oil in the coastal areas of the Persian Gulf, Iran.

Geochemical imprints of occurrence, vertical distribution and sources of aliphatic hydrocarbons, aliphatic ketones, hopanes and steranes in sediment cores from ten Iranian Coral Islands, Persian Gulf

The levels, vertical distribution and sources of hydrocarbons and petroleum biomarkers were estimated for the first time in sediment cores (0-40 cm) from ten coral Islands of the Persian Gulf, Iran. Discrepant hydrocarbons, including linear n-alkanes (n-C₁₁ to n-C₄₀) and isoprenoids (AHs), aliphatic ketones (AKs), hopanes and steranes were measured in all core samples, showing mean concentrations ranging from 209 to 5388 μg g^-1dw (∑₃₀AH), 2-244 μg g^-1-dw (∑₁₃AK), 189-3713 ng g^-1dw (∑₃₁hopane) and 42-3864 ng g^-1dw (∑₁₅sterane), respectively. All sediment cores were found to be petroleum polluted, with ∑₃₀AH > ∑₃₁hopane > ∑₁₅sterane > ∑₁₃AK, with higher levels recorded at 10-20 cm, mainly at industrial sites. Various diagnostic indices revealed that hydrocarbons derived mainly from anthropogenic inputs, with significant contribution of biogenic origin at sites less polluted. Moreover, total organic carbon (0.24-23.45 mg g^-1-dw), terrestrial and marine organic matter had an overwhelming effect on hydrocarbons deposition in sediment cores. Overall, findings provide relevant information for monitoring and preventing petroleum pollution in the sensitive ecosystems of the Persian Gulf.

Potentially toxic elements (PTEs) and polycyclic aromatic hydrocarbons (PAHs) in fish and prawn in the Persian Gulf, Iran

This study aimed to speciate and quantify potentially toxic elements (PTEs) and polycyclic aromatic hydrocarbons (PAHs), in addition to estimate potential human health risk of PTEs (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Se, V, and Zn) through the consumption of three edible fish species (Leuciscus vorax, Liza abu, and Coptodon zillii) and two prawn species (Metapenaeus affinis and Penaeus semisulcatus) collected from Arvand River and Musa Estuary in the Persian Gulf. The concentration of As in prawn species exceeded permissible limit set by international organizations. PAHs were dominated by low molecular weight species such as naphthalene, phenanthrene, and, fluorene but generally exhibited low mean concentrations in fish and prawn samples. The human health hazard posed by PTEs was assessed using methods that consider estimated daily intake (EDI), estimated weekly intake (EWI), target hazard quotients (THQ), and combined THQ. The results suggested that elevated As concentrations in almost all prawn samples may pose a probable health hazard to local inhabitants.

Aliphatic and polycyclic aromatic hydrocarbons in surface seawater of the GULF of Trieste (northern ADRIATIC)

Concentrations, spatial distribution and sources of aliphatic hydrocarbons (AH) and polycyclic aromatic hydrocarbons (PAH) were determined in surface seawater of the Gulf of Trieste, northern Adriatic. This area is one of the most industrialized and urbanized areas in the northern Adriatic with intense maritime traffic. The surface seawater samples were collected at 31 sites and total hydrocarbon concentrations were determined. In general, concentrations (0.1 to 43.2 μg l^-1, mean 4.8 μg l^-1, Chrysene equivalents) were higher in summer. Concentrations of total aliphatic hydrocarbons were from 17.2 to 2326.5 μg l^-1 (mean 543.3 μg l^-1). The major component was the unresolved complex mixture (UCM), comprising from 78% to 97% of the total aliphatic hydrocarbons. Total PAH concentrations varied from 89 ng l^-1 to 294 ng l^-1 (mean 179 ng l^-1). The most contaminated sites were the marina of San Giusto and the municipal harbor of Piran. Different evaluation indeces were applied to determine the origin of hydrocarbons. The prevailing origin of aliphatic hydrocarbons is petrogenic, with the significant contribution of the biogenic at some sites. The results presented indicate the fresh inputs of hydrocarbons, which are subject to intense degradation processes. The PAH group profile showed the predominance of 2-3 ring PAHs. PAHs were of mixed origin with more pronounced petrogenic origin, presumably due to oil spills from ships and boats. The presence of a relatively high content of perylene in seawater is an indication of its terrestrial input. According to the presented results and compared to results from different areas worldwide, the seawater in the Gulf of Trieste can still be considered slightly to moderately polluted with PAHs.

Comparative study of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) in corals, surrounding sediments and surface water at the Dazhou Island, China

This study investigated polycyclic aromatic hydrocarbons (PAHs) content in corals (Acropora sp.), surficial sediments, and surface seawater, and heavy metals (HMs) contents in corals and sediments from Dazhou Island, Hainan, China. Concentrations of PAHs in seawater and sediment seasonally ranged from 191.5 ng L^-1 to 587.7 ng L^-1, and from 37.9 ng g^-1 to 233 ng g^-1, while levels in corals were higher (185.2-545.0 ng g^-1) compared to those found in sediments, demonstrating bioaccumulation of PAHs by corals. A similar seasonally variation of PAHs was observed in water/sediments and corals, and the proportions of low molecular weight PAHs (LPAHs) in seawater and corals were higher. Pyrolytic and petrogenic contaminations were identified to be the main sources of PAHs. Lower HMs concentrations were detected in corals (9.8-39.4 μg g^-1) than in sediments (65.0-83.3 μg g^-1), but HMs bioaccumulation still occurs in corals. Higher concentrations of HMs in sediment and corals were detected in March and December, especially Mn and Zn. Application of an enrichment factor showed that Cu in corals was delivered from non-crustal materials, and anthropogenic inputs were possibly the main sources. According to Biota Sediment Accumulation Factor, corals could strongly bioaccumulate LPAHs and Cd, and PAHs at a higher (p < 0.05) rate than HMs. There was a lack of correlation between the accumulation of PAHs and HMs in corals based on the cluster analysis. Dual hierarchical clustering analysis result revealed that feeding, instead of symbiosis, might be the main process responsible for the bioaccumulation of PAHs and HMs.

Response planning for accidental oil spills in Persian Gulf: A decision support system (DSS) based on consequence modeling

Different causes lead to accidental oil spills from fixed and mobile sources in the marine environment. Therefore, it is essential to have a systematic plan for mitigating oil spill consequences. In this research, a general DSS is proposed for passive and active response planning in Persian Gulf, before and after a spill. The DSS is based on NOAA's advanced oil spill model (GNOME), which is now linked with credible met-ocean datasets of CMEMS and ECMWF. The developed open-source tool converts the results of the Lagrangian oil spill model to quantitative parameters such as mean concentration and time of impact of oil. Using them, two new parameters, emergency response priority number (ERPN) and risk index (RI), are defined and used for response planning. The tool was tested in both deterministic and probabilistic modes, and found to be useful for evaluation of emergency response drills and risk-based prioritization of coastal areas.

Distributions and compositional patterns of polycyclic aromatic hydrocarbons (PAHs) and their derivatives in three edible fishes from Kharg coral Island, Persian Gulf, Iran

This is the first report on bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) and their derivatives (oxygen, nitrogen, sulfur, hydroxyl, carbonyl and methyl-containing PAHs) in three edible marine fishes, namely Lutjanus argentimaculatus, Lethrinus microdon and Scomberomorus guttatus, from Kharg Island, Persian Gulf, Iran. The concentrations (ng g^-1dw) of Σ39PAHs resulted significantly higher in fish liver than muscle, with the PAH composition pattern dominated by low molecular weight compounds (naphthalene, alkyl-naphthalenes and phenanthrene). The highest mean concentrations of ∑9 oxygenated and ∑15 hydroxylated PAHs (ng g^-1dw) were found ound in L. microdon and L. argentimaculatus, respectively, while the lowest values in S. guttatus. Additionally, the highest mean concentrations of Σ5 carbonylic PAHs (ng g^-1dw) were found in L. argentimaculatus, followed by L. microdon. The PAHs levels and distribution in fish liver and muscle were dependent on both the K_ow of PAHs congeners and fish lipid contents. Overall, the present findings provide important baseline data for further research on the ecotoxicity of PAHs in aquatic organisms, and consequent implications for human health.

Polycyclic aromatic hydrocarbons in soil of the backfilled region in the Wuda coal fire area, Inner Mongolia, China

The Wuda coal fire area in Inner Mongolia, China, has existed for 50 years and been controlled by digging and backfilling for many years. However, few studies have focused on its impact on the local environmental and ecological systems due to emission of organic contaminants from the backfilled region. In the study, topsoil samples were collected at a 0-5 cm depth from the backfilled region of the Wuda coal fire area, which has existed for five years. The samples were analyzed for 16 priority control contaminants, namely polycyclic aromatic hydrocarbons (PAHs), with a standard operation procedure and high-performance liquid chromatograph (HPLC). The results showed that the total mass contentration of 16 PAHs (∑₁₆PAHs) ranged from 279 to 8258 μg kg^-1, with an average value of 2853 ± 2948 µg kg^-1, which exceeded the stipulated limit for heavily contaminated soil (1000 μg kg^-1). Among the 16 PAHs, 2- and 3-ring compounds accounted for more than half of ∑₁₆PAHs. Furthermore, the results show that the main contaminants were the naphthalene (Nap), phenanthrene (Phe), pyrene (Pyr), chrysene (Chr), and benzo[b]fluoranthene (BbF) in this area (24.8%, 51.1%, 3.9%, 4.5%, and 5.7% of ∑₁₆PAHs, respectively). The diagnostic ratio of FLA/(FLA + PYR) exceeded 0.4 and IcdP/(IcdP + BghiP) was less than 0.5, indicating gentle smoldering or spontaneous combustion of coal fire, which differs from traditional coal burning. The environmental health risk or specifically the cancer risk (CR), calculated using the surface soil of the backfilled region, was 2.84 × 10^-6 for adults and 1.01 × 10^-6 for children, thus indicating potential cancer risks. Therefore, PAHs pollution in the surface soil of the backfilled region in the studied coal fire area is an issue that deserves urgent attention.

First report of geochemical fractionation distribution, bioavailability and risk assessment of potentially toxic inorganic elements in sediments of coral reef Islands of the Persian Gulf, Iran

Metal contamination is a serious environmental concern in the Middle East. Herein, geochemical fractionation distribution and potential sources of thirteen metals (Fe, Al, Mn, Zn, Cu, Co, Cr, Ni, V, As, Hg, Pb and Cd) were investigated in sediments from ten coral reef Islands in the Persian Gulf, Iran. To properly assess availability and mobility of elements, enrichment factor (EF), pollution load index (PLI), pollution index (PI), contamination index (CI), sediment pollution index (SPI) and ecological risk assessment were provided. Sediment grain size showed an outstanding role in controlling the levels of potentially toxic inorganic elements (PTIEs). The highest values of total organic matter (TOM) were detected in Kharg and Lavan Islands. Different metals fractionation distribution was found across sites. As was noticed in carbonate (F₂), exchangeable (F₁), Fe-Mn oxy-hydroxide (F₃), organic (F₄) and residual (F₅) fractions, Hg primarily associated with F₂ and F₁, whereas Pb and Cd with F₂, followed by F₁, F₃, F₅ and F₄. Conversely, Ni and V accumulated in F₁, suggesting their high mobility and bioavailability, and thus environmental risk to aquatic biota. All metals (except Al, Fe and As) had geological and anthropogenic sources. Based on modified risk assessment analysis, the sediments from Kharg, Lavan, Siri and Lark Islands showed medium adverse effects. Overall, results from this study corroborate that petroleum industry is the main source of pollution of PTIEs in the Persian Gulf, and offer a scientific basis for monitoring and preventing metal pollution in the environment.

Spatio-temporal variability, distribution and sources of n-alkanes and polycyclic aromatic hydrocarbons in reef surface sediments of Kharg and Lark coral reefs, Persian Gulf, Iran

Environmental pollution, particularly oil pollution, has been a long-standing problem in marine areas. With the aim to assess the pollution status in the Persian Gulf, Iran, herein surface sediments were collected from Kharg and Lark coral reefs, in summer (dry season) and winter (wet season), to evaluate the spatio-temporal variations of n-alkanes and PAHs. The mean total organic carbon (TOC⁾ contents of sediments showed a significantly dramatic variation (p < 0.05) in both seasons at both Islands, with high values recorded at sites located near pollutant inputs. The total mean percent of clay grain-sized sediments at Kharg were 26.57% and 28.86% in dry and wet seasons, respectively, while in Lark were 26.73% in summer and 24.57% in winter. Additionally, at Kharg the mean ∑25n-alkanes and ∑30PAHs ranged from 81.35 to 573 µg g^-1 dw and 60.25-491 ng g^-1 dw in dry season, and 171-754 µg g^-1 dw and 41.61-693 ng g^-1 dw in winter, respectively. At Lark, the average ∑25n-alkanes and ∑30PAHs varied from 31.18 to 272 µg g^-1 dw and 41.25-196 ng g^-1 dw in summer, whilst oscillated from 57.99 to 332 µg g^-1 dw and 16.56-487 ng g^-1 dw in wet season, respectively. The lowest mean level of the examined pollutants were spanned in offshore sites, while the highest average concentrations indicated that contaminated sediments were at onshore stations at both Islands in both seasons. Significant seasonal variations (p < 0.05) were observed at most sampling sites for all pollutants. Molecular Diagnostic Ratio (MDR) and Principal Component Analysis (PCA) indicated that n-alkanes and PAHs had mostly a petrogenic source. The compositional profile of PAHs showed that 2 and 3-ring PAHs were abundant at both sampling sites. Significant positive correlation (r > 0.76) was observed between ∑25n-alkanes and ∑30PAHs at Kharg and Lark sediments with TOC content, especially for the sites with high total pollutant concentrations. Based on the potential impact and ecological risk of n-alkanes and PAHs in surface sediments, it is, therefore, necessary in future studies to focus on their effects on corals and other marine organisms within this ecosystem.

First record of bioaccumulation and bioconcentration of metals in Scleractinian corals and their algal symbionts from Kharg and Lark coral reefs (Persian Gulf, Iran)

Metal pollution is nowadays a serious threat worldwide for ecosystem and human health. Despite that, there is still a paucity of data on metal impact on coral reef ecosystems. Herein, the levels of eleven metals (Mn, Zn, Cu, Cr, Co, Ni, V, As, Cd, Hg, Pb) were assessed in surface sediments, seawater samples, Scleractinian corals (tissue and skeleton) and their algal symbionts collected from Kharg and Lark coral reefs in the Persian Gulf, Iran. At Kharg, surface sediments and seawater showed higher concentrations of metals than Lark, attributable to the higher metal loads and petrochemical activities in the area. Sediment quality guidelines indicated Hg as a serious threat to biota both at Kharg and Lark. Accordingly, metals bioaccumulation and bioconcentration was higher in corals from Kharg relatively to Lark Island. Interestingly, as supported by values of BCFs and BSAFs, metal accumulation was higher in coral tissues in respect to skeletons, and in zooxanthellae relatively to coral tissues at both coral reefs. Differential metal bioaccumulation was found among Scleractinian species, indicating that corals have distinct selectivity for assimilating metals from ambient sediments and seawater. Overall, metal accumulation in corals and zooxanthellae is an appropriate tool for environmental monitoring studies in coral reefs. Noteworthy, the use of Porites lutea, among Scleractinian corals, seems to be as a good bioindicator in monitoring studies of metal pollution.

Structural and functional responses of coastal marine phytoplankton communities to PAH mixtures

The toxicity of polycyclic aromatic hydrocarbons (PAHs) mixtures was evaluated on natural phytoplankton communities sampled from lagoons of Bizerte (South-western Mediterranean Sea) and Thau (North-western Mediterranean Sea). PAHs induced short-term dose and ecosystem-dependant decreases in photosynthetic potential. Chlorophyll a was negatively affected by increasing PAHs concentrations, together with dramatic changes in phytoplankton community composition. Size classes were strongly affected in the Bizerte compare to the Thau lagoon, with a decrease in nano- and microphytoplankton densities compare to picophytoplankton. In both locations, the diatom Entomoneis paludosa appeared favoured under PAH exposure as evidenced by increase in cell density, whereas autotrophic flagellates and dinophytes were strongly reduced. Smaller cells were more tolerant to exposure to highest PAHs concentrations, with persistent picophytoplankton carbon biomass at the end of the incubations. Apparent recovery of photosynthetic potential, accompanied with a regrowth of chlorophyll a under the lowest PAH doses, coincided with a significantly altered community composition in both lagoons. Furthermore, sensitivity to PAHs was not related to the phytoplankton cell size, and toxicity-induced modification of top-down control by grazers during the experiment cannot be excluded.

Contamination and health risk assessment of PAHs in farmland soils of the Yinma River Basin, China

The concentration, composition, sources and incremental lifetime cancer risk of farmland soil polycyclic aromatic hydrocarbons (PAHs) of the Yinma River Basin were analyzed. In 2016, the total concentration of 16 PAHs ranged from 491.65 to 1007.73 ng/g in May, from 427.31 to 781.38 ng/g in August and from 580.40 to 999.40 ng/g in November, respectively. Levels of seven potentially carcinogenic PAHs generally accounted for 33-36.7% of total 16 PAHs in three seasons, and the PAHs contained two to six rings, mainly Fla, Pyr, and Chr. The correlation analysis suggested that the soil organic matter (SOM) was no correlation with PAHs except for August, and there were no significant relationship between the pH and total PAHs. Isomer ratios indicated that the soil PAHs in the farmland of the Yinma River Basin was determined to be the combustion of coal, biomass, and petroleum. The toxic equivalent (BaP_eq) concentrations ranged from 15.2 to 133 ng BaP_eq g^-1 in three seasons. The 95th percentiles of incremental lifetime cancer risk (ILCR) due to human exposure to farmland soil PAHs of the Yinma River Basin was (1.36 × 10^-6) in May, (1.00 × 10^-6) in August, and (1.18 × 10^-6) in November for children, (1.10 × 10^-6) in May, (8.15 × 10^-7) in August, and (9.58 × 10^-7) in November for adolescence and (1.61 × 10^-6) in May, (4.22 × 10^-6) in August and (1.40 × 10^-6) in November for adulthood. The result indicated a moderate carcinogenic risk and the risk of exposure to farmland soil PAHs was pervasive for residents. This investigation might provide useful information on human exposure to PAHs in soil of the Yinma River Basin, and is valuable for policy makers and scientists.

First report of bioaccumulation and bioconcentration of aliphatic hydrocarbons (AHs) and persistent organic pollutants (PAHs, PCBs and PCNs) and their effects on alcyonacea and scleractinian corals and their endosymbiotic algae from the Persian Gulf, Iran: Inter and intra-species differences

The coral reefs of the Persian Gulf are the most diverse systems of life in the marine environment of the Middle East. Unfortunately, they are highly threatened by local and global stressors, particularly oil pollutants. This is the first quantitative and qualitative study aimed at assessing the concentration and sources of n-alkanes and POPs (PAHs, PCBs and PCNs) in coral tissues, symbiotic algae (zooxanthellae), reef sediments and seawaters in coral reefs of Lark and Kharg in the Persian Gulf, Iran. This work was conducted on eight species of six genera and three families of hard corals and one family of soft coral. A significant variation in the concentration of ∑30n-alkanes and POPs (∑40PAHs, ∑22PCBs and 20PCNs) was found in the decreasing order: zooxanthellae > coral tissue > skeleton > reef sediment > seawater. The bioaccumulation of these compounds was 2-times higher in ahermatypic than in hermatypic corals, among which significant variations were observed in both sites. In Kharg, Porites lutea had the highest mean concentration of ∑30n-alkanes and ∑40PAHs in soft tissue, whereas the lowest values were in Platygyra daedalea. A contrasting trend was documented for ∑22PCBs and 20PCNs, with the highest level reported in soft tissue of P. daedalea and the lowest in P. lutea at Kharg. Compositional pattern of AHs and PAHs demonstrated the predominance of LMW-PAHs and n-alkanes. In skeleton and reef sediments, tetra, penta and tri-CBs were the most abundant PCBs congeners followed by di-CB > hexa-CB > hepta-CB > octa-CB,whiletri-CB > di-CB > tetra-CB > penta-CB > hexa-CB > hepta-CB > octa-CB was observed for soft tissue, zooxanthellae and seawater. The results of RAD test indicated significantly negative correlation between total concentration of these compounds with zooxanthellae density, the chlorophyll-a and C₂ in corals at both reefs. This is the first report on levels, health assessment and source apportionments of POPs in zooxanthellae and a first step in the implementation of specific coral reef management measures.

Occurrence, distribution and composition of aliphatic and polycyclic aromatic hydrocarbons in sediment cores from the Lower Fox River, Wisconsin, US

The Lower Fox River is a 39 mile section which supports approximately 270,000 rural inhabitants across 18 counties, 303,000 metropolitan residents in Green Bay and Appleton, Wisconsin, and several large industrial complexes such as paper mills and power plants. This paper presents the distribution and concentrations of aliphatic (n-alkanes) and aromatic hydrocarbons (polycyclic aromatic hydrocarbons [PAHs]) as well as total organic carbon (TOC) in the Lower Fox River to identify the sources of hydrocarbon contamination. Excluding one outlier, percent TOC values were between 0.73 and 19.9% with an average value of 6.74%. Total n-alkanes ranged from 3.51 μg/g to 117 μg/g and showed a strong presence of odd carbon-numbered n-alkane ratios (range of C25 to C35), suggesting source input from terrestrial biomass. The mean polycyclic aromatic hydrocarbon (PAH) concentration was 24,800 ng/g. High molecular weight PAH concentrations dominated the distribution of hydrocarbon contaminants. Cross-plots of PAHs were used to compare diagnostic source ratios of benz[a]anthracene (BaA), chrysene (Chr), fluoranthene (Flu), pyrene (Pyr), anthracene (Ant), phenanthrene (Phe), indeno[1,2,3-cd]pyrene (InP), and benzo[g,h,i]perylene (BghiP) by depth and area. PAH ratios varied slightly with the core depth. Deeper core sections indicated the presence of biomass combustion while the upper core sections indicated combustion of both petroleum and biomass. The PAH toxicity of one core was estimated using toxicity equivalency factors, and the benzo[a]pyrene toxic equivalence quotient totaled 2,293 ng/g-dry wt. Levels of PAHs in sediments are compared with established regulatory values and recommendations are made.