Ecological risk assessment of sedimentary hydrocarbons in a subtropical estuary as tools to select priority areas for environmental management

A comprehensive review of polycyclic aromatic hydrocarbons in Brazilian coastal environments

This study provides an overview of the evaluation of polycyclic aromatic hydrocarbons (PAHs) in the coastal regions of Santos Basin, located in Brazil's Southeast region, the country's most industrialized area. The analysis is based on data compiled from various studies in this area since 2000. A comprehensive literature review was conducted using the SCOPUS database, encompassing peer-reviewed scientific journals from publishers such as Elsevier, Springer, Nature, Wiley, Taylor & Francis, Google Scholar, and ResearchGate. Most of these studies have focused on the sediment compartment due to its role as the primary repository for organic matter and, consequently, PAHs in the marine environment. However, the bioavailability of organic contaminants in sediment is generally lower compared to water and suspended particulate matter, which has received less attention in the context of Santos Basin. The literature search also includes studies evaluating PAH concentrations in organisms to investigate the bioaccumulation rates of these compounds. Data presented in this review primarily originates from coastal and estuarine areas within Santos Basin, with occasional extensions to the continental shelf. The majority of publications are centered on studies conducted in the southeastern Brazilian states of São Paulo and Rio de Janeiro, where the highest levels of PAH contamination across all environmental compartments are typically observed. Santa Catarina, on the other hand, is the coastal region with fewer studies. The regions where most of the studies involving PAHs in the Santos Basin are concentrated in areas where public university research centers are located, a pattern that repeats throughout the Brazilian coast. In areas far from universities, little is known about the environmental status of PAHs.

A novel approach to identify priority areas for optimal nutrient management in mixed land-use watersheds through nutrient budget assessment

Excessive nutrient supply in agricultural regions has led to various environmental issues, thereby requiring concentrated management owing to its persistent upward trend. Nutrient budgets (NBs), a vital agricultural environmental indicator, are employed for nutrient management in agricultural areas, using data surveyed by administrative agencies. However, the spatial extent of nutrient data for nutrient budgeting is limited by administrative boundaries according to the surveying organization, posing challenges in interpreting spatial patterns at the watershed level. In this study, a novel approach was developed to identify priority nutrient management areas by applying hot spot spatial analysis to watershed-level NBs, considering hydrological characteristics. This method was applied to approximately 850 subwatersheds across the Republic of Korea, where land cover characteristics are complex. Reassessing nutrient budgets at the watershed scale, accounting for overlapping administrative boundary areas and crop cultivation ratios, indicated similar levels between the two methods. Hot spot analysis revealed that watersheds with elevated NBs mirrored the spatial patterns of livestock excreta and cropland. The spatial distribution characteristics of watersheds with high nutrient levels in rivers corresponded with the concentration characteristics of industrial and commercial areas. Therefore, applying watershed-level NBs based on land cover ratios that consider nutrient input characteristics in agricultural regions is deemed appropriate for selecting priority nutrient management areas. Collectively, this study presents a method for selecting nutrient management priority areas by simultaneously considering the spatial characteristics of various environmental factors, such as land cover, livestock excreta, river water quality, and land area-based watershed-specific NBs. The proposed approach, considering mixed land cover characteristics, is anticipated to be valuable for selecting priority management areas in watersheds with diverse pollution sources. Future research is needed to explore nutrient budgets within watersheds, the influence of land use on pollution sources, and their correlation with water quality.

Unraveling sources of hydrocarbons in subtropical estuaries with distinct degrees of protection in the Southwestern Atlantic Ocean, Brazil

Sedimentary aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) were studied in subtropical estuaries with distinct degrees of legal protection, located in the Southwestern Atlantic Ocean, São Paulo State, Brazil. A multivariate approach was adopted, using the Hierarchical cluster analysis followed by the Principal Matrix Factorization analysis to support the hydrocarbons sources findings using diagnostic ratios. In general, the sites with the highest values of hydrocarbons were in the vicinity of well-urbanized cities, where sewage discharge, harbor and industrial activities take place. Pyrolitic PAHs were the predominant source of PAHs in the sites. The region can be considered not highly contaminated by hydrocarbons; however, specific sites under local anthropogenic impact from sewage and/or urban drainage, presented relatively high hydrocarbons levels. These findings highlight the importance of sources identification as reliable approach to be included in the management plan of protected areas under the inputs of several vectors of contamination.

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

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

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

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

Sterol and PAHs fingerprint analysis of organic matter at Southeast Brazilian Bay

Southeast Brazilian bays have been increasingly degraded by untreated organic loads. Therefore, to assess fecal contamination status, sediment quality regarding polycyclic aromatic hydrocarbons (PAHs), and sources of organic matter (OM), we have determined fine-grained and total organic carbon (TOC) content and concentrations of PAHs and sterols in twenty-six surface sediment samples in Sepetiba Bay. The fine-grained (1-26 %), TOC (0.20-3.45 %), PAHs (<LQ - 78.27 ng g^-1) and sterols (0.10-21.58 μg g^-1) results showed a decreasing trend from the internal to the external sector of the study area. The diagnostic ratios of selected PAHs and sterols indicated a mixture with significant contribution from continental and pyrolytic OM in all stations. The fecal contamination is significant to the internal sector of Sepetiba Bay. Considering a site-specific sediment quality guidelines (SQGs) the PAHs levels with more restricted benchmark values indicate the harbor and the internal sector as contaminated.

Co-occurrence and potential ecological risk of parent and oxygenated polycyclic aromatic hydrocarbons in coastal sediments of the Taiwan Strait

Thirty-two surface sediment samples, collected from the Taiwan Strait (TWS), were investigated for the occurrence, composition profile, and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (OPAHs). PAHs were ubiquity in the TWS with a total concentration (∑PAHs, excluding naphthalene due to its high volatility) ranging from 17.8-213 ng g^-1. Benzo[b] fluoranthene, fluoranthene, phenanthrene, and pyrene were the predominant PAHs. Also, eight OPAHs were detected, having a cumulative concentration range (∑OPAHs) of 10.5-118 ng g^-1, predominated by anthraquinone and 6H-Benzo[c,d]Pyren-6-one. Higher concentrations of ∑PAHs and ∑OPAHs were detected at sampling sites adjacent to the mainland and in the northwest part of the TWS. The results suggested important continental input, and particle sedimentation under the specific hydrodynamic conditions of the region. Based on the measured concentrations and sediment quality guidelines, PAHs had a limited ecological impact on the area.

Influencing mechanisms of siderite and magnetite, on naphthalene biodegradation: Insights from degradability and mineral surface structure

Biodegradation is the most economical and efficient process for remediating polycyclic aromatic hydrocarbons (PAHs) such as naphthalene (Nap). Soil composition is pivotal in controlling PAH migration and transformation. Iron minerals such as siderite and magnetite are the primary components of soil and sediment and play key roles in organic pollutant biodegradation. However, it is unclear whether siderite and magnetite promote or inhibit Nap biodegradation. The effects of siderite and magnetite on Nap biodegradation were investigated through batch experiments in this study. The results indicated that siderite increased Nap biodegradation efficiency by 7.87%, whereas magnetite inhibited Nap biodegradation efficiency by 3.54%. In the presence of siderite, Nap-degrading bacteria with acid-producing effects promoted siderite dissolution via metabolic activity, resulting in an increased Fe (II) concentration in solution which accelerated the iron reduction process and promoted Nap biodegradation. In addition, the presence of iron minerals altered the genus-level community structure. Anaerobic sulfate-reducing bacteria such as Desulfosporosinus occurred in the presence of siderite, indicating that sulfate reduction occurred in advance under the influence of siderite. In the presence of magnetite, Fe (III) in iron minerals were converted to Fe (II), and under the mediation of microorganisms, Fe (II) combined with carbonate to form secondary minerals (e.g., siderite). Secondary minerals were attached to the surface of magnetite, which inhibited magnetite dissolution and reduced the efficiency of Fe (III) utilization by microorganisms. Furthermore, as the reaction proceeds, acid-producing microorganisms promoted magnetite further dissolution, resulting in a longer duration of the Fe (III) reduction process. Bacteria utilizing sulfuric acid as the terminal electron acceptor consumed organic matter more rapidly than those using iron as the terminal electron acceptor. Therefore, magnetite inhibited Nap degradation. These observations enhance our understanding of the interaction mechanisms of iron minerals, organic pollutants, and degrading bacteria during the biodegradation process.

Experimental study on the biodegradation of naphthalene and phenanthrene by functional bacterial strains in the riparian soil of a binary system

Polycyclic aromatic hydrocarbons (PAHs) such as naphthalene (Nap) and phenanthrene (Phe) are organic pollutants of concern owing to their toxicity, carcinogenicity, and teratogenicity. Biodegradation is considered the most economical and efficient process to remediate Nap and Phe. The riparian zone between a river and a riparian aquifer, which is rich in indigenous microorganisms, may be important for PAH remediation. However, few studies have evaluated the ability of indigenous microorganisms to remove Nap and Phe. In this study, focusing on the typical PAHs (Nap and Phe) as target pollutants, the genus-level community structure of Nap- and Phe-degrading bacteria was identified. Batch static and dynamic biodegradation experiments were conducted to explore the biodegradation mechanisms of Nap and Phe in the riparian zone and identify the factors influencing Nap and Phe biodegradation in the binary system (i.e., where Nap and Phe are simultaneously present). According to the genus-level community structure test results, the dominant bacterial genus in the binary system was mainly the Phe-degrading bacteria. The Nap and Phe-biodegradation percentages were 19.20% lower and 19.49% higher, respectively, in the binary system than in the unitary system. The results indicated that functional bacteria can degrade Nap and Phe, and that Nap weakly promoted Phe biodegradation. Additionally, the initial Nap and Phe concentration ratio, hydraulic gradient, and temperature affected Nap and Phe biodegradation. Dynamic biodegradation experiments showed that the biodegradation percentage decreased as the hydraulic gradient increased, and biodegradation percentage of Phe was always higher than that of Nap. According to the results of the dynamic laboratory experiments, the removal percentages of Nap and Phe by indigenous riparian-zone microorganisms were 6.21-16.73% and 13.95-24.45%, respectively. The findings in this study will be useful for alleviation of Nap and Phe pollution in groundwater and will facilitate determination of appropriate treatment measures for groundwater exposed to this type of pollution.

Enzyme-assisted bioremediation approach for synthetic dyes and polycyclic aromatic hydrocarbons degradation

Environmental protection from emerging pollutants has become a significant challenge for mankind as an increasing number of contaminants, including synthetic dyes and polycyclic aromatic hydrocarbons (PAHs), represent a serious risk to ecological and environmental balance. Most synthetic dyes have complex aromatic structures and are resistant to degrade by classical approaches, such as physical and chemical processes, including adsorption, chemical coagulation, flocculation, ion exchange, membrane separation, froth flotation, and reverse osmosis. Enzymes-assisted catalytic transformation of pollutants has become a potential alternative to classical methods because of their ability to react with complex compounds, a quick degradation rate, and producing less harmful by-products. Plant peroxidases, and microbial laccase and lignin-degrading peroxidases (manganese and lignin peroxidase) have gained significant attention for treating aromatic waste due to their capability of oxidizing and detoxifying a wide range of recalcitrant xenobiotics, including PAHs and synthetic dyes. Peroxidases being efficient biocatalysts detoxify an array of toxic compounds by simple free-radical mechanism resulting in the formation of oxidized and depolymerized products of significantly reduced toxicity. Moreover, it is an ecofriendly and economically favorable approach towards the biodegradation of recalcitrant and toxic industrial waste. Among microbial and plant peroxidases, bacterial enzymes have broad substrate specificity and can transform a wide range of recalcitrant substrates. Ligninolytic enzymes oxidize the aromatic ring into quinones and acids by producing free hydroxyl radicals instead of dihydrodiols and mineralize aromatic hydrocarbon in combination with cytochrome P450, monooxygenases, and epoxide hydrolases. In the review, an attempt has been made to provide detailed knowledge about the availability of inexpensive peroxidases sources, their mechanism of action, and degradation potential. The present review summarizes the exploitation of peroxidases from plants, bacteria, and fungus (manganese peroxidase, lignin peroxidase, and laccases) for detoxification and degradation of textile dyes as well as PAHs. Conclusively, peroxidases have great potential to react with almost all classes of synthetic dyes and most PAHs due to broad substrate specificity and transformed them into less harmful metabolites.

Historical deposition of PAHs in mud depocenters from the Southwestern Atlantic continental shelf: The influence of socio-economic development and coal consumption in the last century

Polycyclic aromatic hydrocarbon (PAH) concentrations were determined in four dated sediment cores collected in mud depocenters of the southern Brazilian continental shelf. Core dating results covered the interval between 1925 and 2017. The total PAH concentrations (ΣPAHs) ranged from 44.69 ng g^-1 to 305.43 ng g^-1 and were similar between the analysed cores. Fine-grained sediments and total organic carbon (TOC) results did not correlate with the ΣPAHs, indicating that the variations in PAH concentrations are mostly related to variations in sources and emissions. PAH source appointment indicated a high input of a natural compound (perylene) and the predominance of anthropogenic PAHs from coal, biomass, and fuel combustion. Alkylated PAHs presented high contributions throughout all cores. The historical deposition of PAHs was associated with different periods of the socio-economic and industrial development of near coastal cities and reflected very well the history of coal production and consumption in the southern region of Brazil. The low levels of ΣPAHs before 1945 in all analysed cores may be related to the beginning of the industrialization process and the lower urbanization degree in the region. Between 1945 and 1965, the gradual ΣPAHs increase reflects the establishment and enlargement of the southern Brazilian industrial sector. The interval between 1965 and 1990 corresponded to the highest ΣPAHs in three of the four analysed cores. After 1990, a relative decrease in the ΣPAHs was observed in most cores and may be related the multiple cuts of incentives to the industrial usage of coal, as well as to Brazil's efforts in environmental regulation for coal extraction and consumption.

Does the environmental condition affect the tolerance of the bivalve Anomalocardia flexuosa to different intensities and durations of marine heatwaves?

Populations of the clam Anomalocardia flexuosa, subjected to different pollution conditions, were experimentally exposed to marine heatwaves of actual and future intensities and varying durations. We measured physiological and biochemical biomarkers and survival rates of the species under simulated heatwave events of 7 and 11 days. We observed that both the response of A. flexuosa to heatwaves and its baseline values of biomarkers were distinct between populations, demonstrating that the previous exposure to contaminants negatively interferes with the thermal tolerance of this bivalve. The duration and intensities of heatwaves here tested represent a considerable challenge for the survival of coastal bivalves. Our results suggest that the predicted increase in the ocean's average temperature and the frequency and intensity of marine heatwaves, as well as urbanization and increasing occupation of coastal regions, are factors that synergistically make A. flexuosa increasingly vulnerable over the decades.

Ecological quality assessement of marinas: An integrative approach combining biological and environmental data

The importance of marinas as infrastructures for recreational boating is increasing substantially. However, information on their soft-bottom benthic communities, a key tool for managing programmes, is still scarce. We combined environment features with macro- and meiofaunal soft-bottom community information for assessing the ecological status of marinas with an integrative approach. To address this issue, we focused on eight marinas of the Southern Iberian Peninsula. Macro- and meiofauna data revealed high benthic heterogeneity at a spatial scale. The environmental variables which correlated best with macrofauna were mainly phosphorus, granulometry, and total organic carbon, and secondarily important variables were faecal coliforms, the biocide Irgarol, and heavy metals; total hydrocarbon concentration was also significant for meiofauna. Annelida was the dominant phylum in terms of number of species (37%) and abundance (66%) and were better descriptors of the environmental conditions than Arthropoda and Mollusca. Although identification to the species level is desirable and mandatory for assessing biological pollution, significant differences among marinas and correlations between fauna and abiotic variables were already detected at the level of family and order. This implies that biota assessment at higher levels may still be useful in monitoring programmes limited by time and budget constraints. The major novelty of this study lies in the development of an integrative assessment method based on the following selected ecological indicators: Marinas Environmental Pollution Index (MEPI), Biocontamination Index (BCI), macrofaunal biotic indices (AMBI, M-AMBI, BENTIX, MEDOCC and BENFES), macrofaunal taxa richness and Shannon-Wiener's diversity, and nematode:copepod index. This approach was able to discriminate marinas of the Southern Iberian Peninsula based on their ecological status, which ranged from poor to good. The method can be useful to design standards for assigning "sustainable quality seals" to those marinas with better values of ecological indicators.

Effect of soil organic matter (SOM) on the degradation of polycyclic aromatic hydrocarbons using Pleurotus dryinus IBB 903-A microcosm study

Bioremediation of polycyclic aromatic hydrocarbons (PAHs) in soil matrix is often arbitrated by the presence of soil organic matter (SOM). The present study focuses on determining the effect of the soil organic content on the mycoremediation of two model PAHs, phenanthrene (Phe) and benzo(a) pyrene (BaP) through microcosm studies. On comparing various microcosm strategies, a maximum degradation of Phe (99%) and BaP (48.5%) in soil bioaugmented with Pleurotus dryinus IBB 903, followed by, biostimulation with the degradation of Phe (89.9%) and BaP (24.8%) were noted. On relating the degradation pattern with lignolytic enzyme cocktail production, a laccase activity of 108 U/Kg at day 21, aryl alcohol oxidase (411 U/Kg) and manganese peroxidase (52.2 U/Kg) at day 14 along with lignin peroxidase (481 U/Kg) at day 21 were noted in fungal augmented soils, which were comparatively higher than levels observed in the bio-stimulation. Investigating the impact of different concentration of SOM (3-12%), a maximum remediation of Phe by 100% at 9% SOM in days 28 and 58.19% for BaP at 12% SOM, respectively was exhibited. Further, the biosorption effect of PAHs in abiotic condition showed a positive correlation with the increase in SOM, with a maximum adsorption of 3.78% Phe, and 6.93% BaP. The results support that the nominal adsorption ability of SOM, and helps in enhancing the microbial growth, thereby improving their degradation potentials, when less than 6% of SOM was utilized. Overall, this work establishes the critical role of organic matter in the soil with reference by simultaneous stimulation and degradation capability in complete PAHs remediation.

One century of historical deposition and flux of hydrocarbons in a sediment core from a South Atlantic RAMSAR subtropical estuary

Levels and fluxes of Polycyclic aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons (AHs), including n-alkanes and petroleum biomarkers (PBMs), were measured in a sedimentary core from a nominated RAMSAR (Guaratuba Bay, Brazil) subtropical estuary experiencing relatively low human impacts, to describe the evolution of anthropogenic activities over the last century. TOC contents varied from 0.80 to 1.25%. No significant correlation between hydrocarbons and TOC with grain size (predominantly sand) was observed. Concentration and flux of total AHs ranged from 65.5 to 195 μg g^-1 and 27.6 to 82.0 μg cm^-2 y^-1, respectively, with the highest levels found in 1960-1966, when access routes to Guaratuba city were improved. Diagnostic ratios based on AH components showed an apparent change in the sources over time, with biogenic origins prevailing until 1966-1971, followed by subsequent increases in petroleum sources. Petroleum tricyclic terpanes were detected in the core (0.40 to 3.0 μg g^-1), suggesting the use of lubricating oil in the bay area. Hopanes were mainly attributed to biological sources. Concentration and flux of total PAHs ranged from 8.65 to 35.9 ng g^-1 and 3.64 to 15.1 ng cm^-2 y^-1, respectively, with the highest levels found in the top core section, reflecting recently increased human activity, while a peak PAH concentration at approximately 1977-1983 can be assumed to be a delayed signal of increased human occupation as a consequence of the improvement of access roads to the area, which started in the 1960s. Alkylated were the most abundant group of PAHs throughout the core. Despite relatively low concentrations of hydrocarbon deposition over approximately 90 years, this study highlights the influence of human occupation and slight petroleum contamination in this preserved area, mainly in recent core sections.

Urban effluents affect the early development stages of Brazilian fish species with implications for their population dynamics

The pollution from urban effluents discharged into natural waters is a major cause of aquatic biodiversity loss. Ecotoxicological testing contributes significantly to understand the risk of exposure to the biota and to establish conservation policies. The objective of the current study was to assess the toxicity of a river highly influenced by urban effluents (Atuba River, Curitiba city, Southern Brazil) to the early stages of development in four South American native fish species, investigating the consequences at the population level through mathematical modelling. The species chosen were Salminus brasiliensis, Prochilodus lineatus, Rhamdia quelen, and Pseudoplatystoma corruscans, ecologically important species encompassing different conservation statuses and vulnerability. The embryos were exposed from 8 to 96 h post fertilization to the Atuba River water, collected downstream of the largest wastewater treatment plant in the Metropolitan Region of Curitiba, and their survival rates and deformities were registered. The species S. brasiliensis and P. lineatus presented the highest mortality rates, showing high sensitivity to the pollutants present in the water. According to the individual-based mathematical model, these species showed high vulnerability and risk of extinction under the tested experimental conditions, even when different sensitivity scenarios of juveniles and adults were considered. The other two species, R. quelen and P. corruscans, showed a more resistant condition to mortality, but also presented high frequency and severity of deformities. These results emphasize the importance of testing the sensitivity of different Brazilian native species for the conservation of biodiversity and the application of models to predict the effects of pollutants at the population level.

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.

Influence of sediment parameters on the distribution and fate of PAHs in an estuarine tropical region located in the Brazilian semi-arid (Jaguaribe River, Ceará coast)

18 polycyclic aromatic hydrocarbons (PAHs) were evaluated in the Jaguaribe River to explore the influence of grain size, organic carbon, humic and fulvic acids and black carbon on their adsorption onto sediment. The ∑PAHs concentrations variated from 0.6 to 3752.0 ng g^-1 with highest concentrations in the estuarine zone. The PAHs predominant source along the river was from mixed sources, mainly related to biomass combustion, small oil spills related to recreational nautical activities and runoff from cities. Organic and inorganic parameters presented influence on PAHs distribution along the river, with humic acid as a determinant factor. These research findings are of importance to an assessment of the fate and transport of PAHs in estuarine systems.

Distribution and sources of polycyclic aromatic hydrocarbons (PAHs) in surface sediments of a Tropical Bay influenced by anthropogenic activities (Todos os Santos Bay, BA, Brazil)

The present study aimed to evaluate the distribution and origin of 16 Priority PAHs in surficial sediment samples of Todos os Santos Bay (TSB, Brazil). Total PAHs concentrations ranged from below the method detection limit (<DL) to 533 ng g^-1 (dry weight). The toxic equivalent concentrations (TEQ^carc) of PAHs in the studied area ranged from 0 to 104 ng g^-1 and were lower when compared to other contaminated bays in the world. Diagnostic ratios indicated that pyrogenic processes, such as pyrolysis of fossil fuel, biomass, and coal, were the main PAHs sources for sediments. Proximity of the sources, the hydrodynamics and geochemistry of the sediments were the factor influencing the distribution of PAHs along the studied area.