Polycyclic aromatic hydrocarbons (PAH) in superficial water from a tropical estuarine system: Distribution, seasonal variations, sources and ecological risk assessment

Efficient PAHs removal and CO2 fixation by marine microalgae in wastewater using an airlift photobioreactor for biofuel production

Microalgae cultures have emerged as a promising strategy in diverse areas, ranging from wastewater treatment to biofuel production, thus contributing to the search for carbon neutrality. These photosynthetic organisms can utilize the resources present in wastewater and fix atmospheric CO2 to produce biomass with high energy potential. In this study, the removal efficiency of Polycyclic Aromatic Hydrocarbons (PAHs), CO2 fixation and lipid content in the biomass produced from microalgae grown in airlift photobioreactor were evaluated. Four mesoscale cultures were carried out: Control (Seawater + Conway medium), Treatment A (Oil Produced Water + Poultry Effluent Water), Treatment B (Poultry Effluent Water + Seawater) and Treatment C (Oil Produced Water, Seawater and nutrients). The impact of biostimulation, through the addition of nutrients, on PAHs removal efficiency (up to 90%), CO2 fixation rate (up to 0.20 g L-1 d-1) and the composition of the generated biomass was observed. Primarily, the addition of nitrates to the culture medium impacted CO2 fixation rate of the microalgae. In addition, a direct correlation was observed between PAHs removal and lipid accumulation in the biomass, up to 36% in dry weight, demonstrating microalgae's ability to take advantage of the organic carbon (PAHs) present in the culture medium to generate lipid-rich biomass. The concentration of polysaccharides in the biomass obtained did not exceed 12% on a dry weight basis, and the Higher Heating Value (HHV) ranged between 17 and 21 MJ kg-1. Finally, the potential of generating hydrogen through pyrolysis was highlighted, taking advantage of the characteristics of biomass as a conversion route to produce biofuels. These results show that microalgae are effective in wastewater treatment and have great potential in producing biofuels, thus contributing to the transition towards more sustainable energy sources and climate change mitigation.

Ecotoxicological and health risks associated with sediment-bound polycyclic aromatic hydrocarbons in peri-urban closed and open coastal lagoons

Coastal urbanisation has ramifications for the sustainable development of developing nations. There are often unquantified ecological and health risks associated with urbanisation. Sixteen polycyclic aromatic hydrocarbons (PAHs) were analysed in surface sediment from three peri-urban coastal lagoons in southern Ghana. We found significant spatial variations of sediment PAHs. These variations were attributed to physiography of the lagoons and diverse anthropogenic activities surrounding them. Total PAHs ranged from 20.81 to 24,801.38 μg/kg (dry weight), underscoring a low to very high pollution level. Diagnostic ratios revealed both pyrogenic and petrogenic origins. Over 50 % of individual PAHs were of moderate ecological risk to benthic organisms, and cancer risk to humans was above the World Health Organisation's recommended safety limit (1 × 10-6). These ecological and health risks should be wake-up call for a more integrated urban planning approach to coastal urbanisation as coastal communities largely depend on natural ecosystems for food and livelihood opportunities.

Polycyclic aromatic hydrocarbons in surface water of rivers in Sergipe State, Brazil: A comprehensive analysis of sources, spatial and temporal variation, and ecotoxicological risk

This study conducted in Sergipe State, Brazil, aimed to investigate the presence of polycyclic aromatic hydrocarbons (PAHs) in the surface water of five rivers, determining their sources, spatial and temporal variations, and ecotoxicological risks. Correlation and principal component analyses were utilized to identify the relationship between PAH concentrations and water sample properties. Results indicated higher PAH concentrations during the rainy season, attributed to increased run-off and sediment resuspension. The composition of PAHs suggested a main petroleum source with organic material combustion in minor scale. Ecological risk assessment revealed potential risks to the ecosystem, emphasizing the need for continuous monitoring of PAHs pollution. This study highlights the importance of understanding and mitigating PAHs contamination in rivers to protect aquatic ecosystems.

Enhancement of benzo[a]pyrene mineralization: symbiotic biodegradation by Acinetobacter sp. strain HAP1 in Association with Cyanobacteriota sp. S66

The ability of Acinetobacter sp. strain HAP1, isolated from petroleum refinery effluent, to eliminate different concentrations (20, 40, 60, 80 and 100 mg/L) of Benzo[a]Pyrene degradation (BaP) was studied. A test to improve this degradation capacity was carried out by culturing the bacterial strain in association with a cyanobacteria. The results show a highly significant effect of the concentration of (BaP) and a very highly significant effect of the symbiosis between the bacterial strain and the cyanobacteria. This combination was able to significantly improve the (BaP) degradation rate by up to 18%. This degradation and especially in association leads to a complete mineralization of (BaP) and there is a difference in yield that can go up to 15%. Through molecular identification based on 16S rRNA gene sequence analysis, strains HAP1 and S66 were recognized as Acinetobacter sp. strain HAP1 and Cyanobacteriota sp. S66, respectively. Comparison of the retrieved sequences with the NCBI GenBank database was done, and the closest matches were found to be Acinetobacter pittii strain JD-10 for bacteria and Pseudochroococcus couteii strain PMC 885.14 for cyanobacteria.

Detection and treatment of mono and polycyclic aromatic hydrocarbon pollutants in aqueous environments based on electrochemical technology: recent advances

Mono and polycyclic aromatic hydrocarbons are widely distributed and severely pollute the aqueous environment due to natural and human activities, particularly human activity. It is crucial to identify and address them in order to reduce the dangers and threats they pose to biological processes and ecosystems. In the fields of sensor detection and water treatment, electrochemistry plays a crucial role as a trustworthy and environmentally friendly technology. In order to accomplish trace detection while enhancing detection accuracy and precision, researchers have created and studied sensors using a range of materials based on electrochemical processes, and their results have demonstrated good performance. One cannot overlook the challenges associated with treating aromatic pollutants, including mono and polycyclic. Much work has been done and good progress has been achieved in order to address these challenges. This study discusses the mono and polycyclic aromatic hydrocarbon sensor detection and electrochemical treatment technologies for contaminants in the aqueous environment. Additionally mentioned are the sources, distribution, risks, hazards, and problems in the removal of pollutants. The obstacles to be overcome and the future development plans of the field are then suggested by summarizing and assessing the research findings of the researchers.

Mapping chemical footprints of organic micropollutants in European streams

There is increasing awareness that chemical pollution of freshwater systems with complex mixtures of chemicals from domestic sources, agriculture and industry may cause a substantial chemical footprint on water organisms, pushing aquatic ecosystems outside the safe operating space. The present study defines chemical footprints as the risk that chemicals or chemical mixtures will have adverse effects on a specific group of organisms. The aim is to characterise these chemical footprints in European streams based on a unique and uniform screening of more than 600 chemicals in 445 surface water samples, and to derive site- and compound-specific information for management prioritisation purposes. In total, 504 pesticides, biocides, pharmaceuticals and other compounds have been detected, including frequently occurring and site-specific compounds with concentrations up to 74 µg/L. Key finding is that three-quarter of the investigated sites in 22 European river basins exceed established thresholds for chemical footprints in freshwater, leading to expected acute or chronic impacts on aquatic organisms. The largest footprints were recorded on invertebrates, followed by algae and fish. More than 70 chemicals exceed thresholds of chronic impacts on invertebrates. For all organism groups, pesticides and biocides were the main drivers of chemical footprints, while mixture impacts were particularly relevant for invertebrates. No clear significant correlation was found between chemical footprints and the urban discharge fractions, suggesting that effluent-specific quality rather than the total load of treated wastewater in the aquatic environment and the contribution of diffuse sources, e.g. from agriculture, determine chemical footprints.

Spatiotemporal distribution and particle-water partitioning of polycyclic aromatic hydrocarbons in Bohai Sea, China

The Bohai Sea is one of the most polluted marine areas in China with polycyclic aromatic hydrocarbons (PAHs) due to its unique hydrological and geographical environment. To investigate differences in PAH concentrations, composition, and particle-water partitioning before and after the rainy reason, water samples were collected during two surveying voyages covering most of the area of the Bohai Sea. Total and dissolved PAH concentrations were higher during the June voyage (total PAHs: 32.29 ± 15.18 ng/L, dissolved PAHs: 31.25 ± 15.26 ng/L) than the August voyage (total PAHs: 15.98 ± 6.39 ng/L, dissolved PAHs: 11.21 ± 5.59 ng/L). The opposite trend was observed for particulate PAHs (June: 1.04 ± 1.01 ng/L, August: 4.78 ± 2.96 ng/L). Among particulate PAHs, an unusually high proportion (65.07%) of low-molecular-weight (LMW) PAHs was observed during the August voyage, which was significantly higher than the proportion during the June voyage (21.86%). This high proportion was inconsistent with the general distribution of PAHs in the aquatic environment according to their physicochemical properties. The excess LMW PAHs adsorbed on suspended particulate matter arose mainly from soil affected by the petrochemical industry of the Bohai Economic Rim, and were carried with particles on runoff into the Bohai Sea during the rainy season. An estimated 5.49 t of LMW PAHs transitioned from the particulate phase to the dissolved phase during the rainy season. This transfer of LMW PAHs from coastal soil to the water column may be an important source of PAHs in the Bohai Sea.

Ecological risk assessment for xylenes and propylbenzenes in aquatic environment using a species sensitivity distribution approach

Xylenes and propylbenzenes (PBZs) are volatile aromatic hydrocarbons with high aquatic toxicity. Xylenes can be present in three isomers: o-xylene (OX), m-xylene (MX), and p-xylene (PX), while PBZs include two isomers: n-propylbenzene (n-PBZ) and isopropylbenzene (i-PBZ). Their accidental spills and improper discharges from petrochemical industries can cause severe contamination in water bodies posing potential ecological risks. In this study, the published acute toxicity data of these chemicals for aquatic species were collected to calculate hazardous concentrations protecting 95% species (HC₅) using a species sensitivity distribution (SSD) approach. The acute HC₅ values for OX, MX, PX, n-PBZ, and i-PBZ were estimated to be 1.73, 3.05, 1.23, 1.22, and 1.46 mg/L, respectively. The risk quotient (RQ) values calculated based on HC₅ indicated their high risk (RQ: 1.23 ∼ 21.89) in groundwater, but low risk (RQ < 0.1) in natural seawater, river water, and lake water. When xylenes or PBZs leaked into the sea, they were expected to pose a high risk (RQ > 1) at the start and then a low risk (RQ < 0.1) after 10 days due to natural attenuation. These results may help to derive more reliable protection thresholds for xylenes and PBZs in aquatic environment and provide a basis for evaluating their ecological risks.

A Current Review of Water Pollutants in American Continent: Trends and Perspectives in Detection, Health Risks, and Treatment Technologies

Currently, water pollution represents a serious environmental threat, causing an impact not only to fauna and flora but also to human health. Among these pollutants, inorganic and organic pollutants are predominantly important representing high toxicity and persistence and being difficult to treat using current methodologies. For this reason, several research groups are searching for strategies to detect and remedy contaminated water bodies and effluents. Due to the above, a current review of the state of the situation has been carried out. The results obtained show that in the American continent a high diversity of contaminants is present in the water bodies affecting several aspects, in which in some cases, there exists alternatives to realize the remediation of contaminated water. It is concluded that the actual challenge is to establish sanitation measures at the local level based on the specific needs of the geographical area of interest. Therefore, water treatment plants must be designed according to the contaminants present in the water of the region and tailored to the needs of the population of interest.

Impact of petroleum refinery on aquatic ecosystem of Skikda Bay (Algeria): Diversity and abundance of viable bacterial strains

This paper reports a study on the impact of petroleum refinery effluents on the bacterial load and diversity of the aquatic ecosystem in Skikda Bay (Algeria). The results showed a large spatiotemporal variation in the isolated bacterial species. This difference between stations and seasons could be attributed to environmental factors and to the pollution rate at the different sampling sites. Statistical analysis results showed that physicochemical parameters such as pH, electrical conductivity and salinity have a very significant effect on the microbial load (p < 0.001), while hydrocarbon pollution has a significant effect on the diversity of bacterial species (p < 0.05). In total 75 bacteria were isolated from six sampling sites during the four seasons. A significant spatiotemporal richness and diversity was observed in water samples. A total of 42 strains belonging to 18 bacterial genera were identified. Most of these genera belong to the class of Proteobacteria.

Determination of Pollution and Environmental Risk Assessment of Stormwater and the Receiving River, Case Study of the Sudół River Catchment, Poland

Changes in the land use of urban catchments and the discharge of stormwater to rivers are causing surface water pollution. Measurements were taken of the quality of discharged stormwater from two areas with different types of development: a residential area and a residential-commercial area, as well as the quality of the Sudół River water below the sewer outlets. The following indicators were studied: TSS, COD, N-NO₃, N-NO₂, TKN, TN, TP, Zn, Cu, Hg, HOI, and PAHs. The influence of land use on the magnitudes of flows in the river was modeled using the SCS-CN method and the Snyder Unit Hydrograph Model. The results showed an increase in sealing and a resulting increase in surface runoff. Concentrations of pollutants in stormwater and analysis of the potential amounts of loadings contributed by the analyzed stormwater outlets indicate that they may be responsible for the failure to meet environmental targets in the Sudół River. Environmental risk assessment shows that the aquatic ecosystem is at risk. A risk factor indicating a high risk of adverse environmental effects was determined for N-NO₃, Zn, and Cu, among others.

Occurrence of polycyclic aromatic hydrocarbons, microplastics and biofilms in Alqueva surface water at touristic spots

Freshwater pollution is a huge concern. A study aiming to evaluate physico-chemical characteristics, microbiota, occurrence of two groups of persistent environmental pollutants with similar chemical properties (polycyclic aromatic hydrocarbons- PAHs and microplastics - MPs) in Alqueva's surface water was performed during 2021. Water samples were collected at three spots related to touristic activities (two beaches and one marina) during the Winter, Spring, Summer and Autumn seasons. In addition, the presence of biofilms on plastic and natural materials (stone, wood/ vegetal materials) were assessed and compared. Water quality based on physicochemical parameters was acceptable with a low eutrophication level. PAHs concentration levels were lower than the standard limits established for surface waters by international organizations. However, carcinogenic compounds were detected in two sampling locations, which can pose a problem for aquatic ecosystems. PAHs profiles showed significant differences when comparing the dry seasons with the rainy seasons, with a higher number of different compounds detected in Spring. Low molecular weigh compounds, usually associated with the atmospheric deposition and petroleum contamination, were more prevalent. MPs were detected in all samples except one during the Winter season. The polymers detected were poly(methyl-2-methylpropenoate), polystyrene, polyethylene terephthalate, polyamide, polypropylene, styrene butadiene, polyvinyl chloride and low /high density polyethylene with the last being the most frequent. Biofilms were more often detected on plastics than on natural materials. In addition, biofilms detected on plastics were more complex with higher microbial diversity (e.g., bacteria, fungi/yeast and phytoplancton organisms) and richer in extrapolymeric material. Based on morphological analysis a good agreement between microbiota and microorganism present in the biofilms was found. Among microbiota were identified microorganisms previously linked to plastic and PAHs detoxification suggesting the need for further studies to evaluate the viability of using biofilms as part of a green bioremediation strategy to mitigate water pollution.

Legacy and emerging pollutants in Latin America: A critical review of occurrence and levels in environmental and food samples

The increase and indiscriminate use of personal care products, food products, fertilizers, pesticides, and health products, among others, have resulted/are resulting in extensive environmental contamination. Most of these products contain traces of widespread chemicals, usually known as emerging pollutants (EPs) or pollutants of emerging concern (PEC). The Latin American (LA) region comprises 20 countries with different social and cultural aspects, with 81 % of the population living in urban areas. The LA region has some countries on the top list of users/consumers of EPs, from pesticides and fertilizers to personal care products. However, there is a gap in information related to the distribution of EPs in the environment of this region, with very few existing review texts exploring this issue. Therefore, this present paper advances this approach. An exhaustive literature review, with the selection of 176 documents, provided unique up-to-date information on the presence/distribution of 17 classes of legacy or emerging pollutants in different food and environmental matrices (soil, sediment, water, and air). The study shows that the wide distribution and recorded levels of these pollutants in the continental environment are potential risks to human health, mainly through food and drinking water ingestion. Polycyclic aromatic hydrocarbons are pollutants of deep public concern since they show carcinogenic properties. Several classes of pollutants, like endocrine disruptors, have caused harmful effects on humans and the environment. Besides that, pharmaceutical products and pesticides are compounds of high consumption worldwide, being environmental contamination a real and ongoing possibility. Finally, gaps and future research needs are deeply pointed out.

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

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

Levels, source appointment, and ecological risk of petroleum hydrocarbons in tropical coastal ecosystems (northeast Brazil): Baseline for future monitoring programmes of an oil spill area

We reviewed 20 years of levels, sources, and environmental risks related to the main petroleum hydrocarbons in the northeast region of Brazil. The aim of this study was to conduct a systematic review to serve as a comprehensive baseline for future monitoring programmes related to the oil spill disaster in 2019/2020. Most contamination levels of both PAHs and AHs were classified as low, except those in specific areas influenced by human activities, such as ports, highly urbanised mangroves, or rivers of medium-sized cities with inadequate liquid and solid waste treatment. Most hydrocarbons were linked to natural sources and burning processes, except in regions of extraction activities and petrochemical facilities as well as highly urbanised areas, where degraded petroleum and oil hydrocarbons predominated. Only 2.5% of the samples exceeded threshold effect levels for ∑_16-PAHs and no samples exceeded probable effect levels. When regional threshold levels were used, however, the probable effect for the ∑_16-PAHs measured was high, ranging from 5.8 to 6.1%. The few studies reporting biological responses showed that hydrocarbons from anthropogenic sources can induce adverse effects on marine organisms even at low to moderate levels. As the region has recently received a considerable quantity of crude oil, studies should be prioritised for a more precise assessment of the impact of this oil spill.

Human serum elements' levels and leukemia: A first pilot study from an adult Greek cohort

BACKGROUND

The present study focuses on the evaluation of potential relationships between trace elements and acute and chronic types of leukemia, via the determination of their levels in human blood serum.

METHODS

A total of 199 serum samples from a Greek cohort were examined, including both leukemia cases and controls. Elements' analysis was carried out using inductively coupled plasma mass spectrometry (ICP-MS) and demographic features such as age, gender, smoking habits and area of residence were recorded and statistically treated applying Shapiro-Wilk, Kolmogorov-Smirnov, Mann Whitney and Kruskal Wallis tests (p < 0.05). Spearman correlation and principal component analysis (PCA) were also performed to investigate possible associations.

RESULTS

The results demonstrated significantly higher (p < 0.05) trace elements concentrations in cases' serum compared to that of controls excluding Ba, with Cu (median concentration 1295 μg L^-1) being the most abundant in cases. Additionally, concentration of toxic Pb and Cd were found at seven and four fold higher concentrations in cases, respectively. Among the trace elements examined, only Rb (164 μg L^-1) was detected in higher concentrations in controls. Ba, Cd and Co presented the lowest concentrations (lower than 1 μg L^-1). PCA was performed for overall and classified data, indicating a stronger relation among the toxic As, Cd, Ni and Pb in cases than controls, particularly referring to smokers and industrial sites' residents. Hematological parameters and factors such as age and gender did not present any significant outcome or correlation.

CONCLUSIONS

The findings from this pilot study suggest a potential relationship between metals and leukemia, especially concerning the toxic ones. Results from the employed source apportionment tools imply that smoking and atmospheric degradation may be positively related with higher metal serum levels in leukemia patients.

Assessment of polycyclic aromatic hydrocarbons in three environmental components from a tropical estuary in Northeast Brazil

The evaluation of occurrence, risk quotient (RQ), bioaccumulation factor (BAF), and sources of PAH was conducted in Sergipe-Poxim estuarine system. PAH distribution that ranged from 7.1 to 30.9 ng L^-1 (surface water, SW), 5.4 to 19.5 ng g^-1 (sediment, S), and 4.3 to 18.1 ng g^-1 (oyster, O), characterized the environment with low contamination; 2-3 (SW), 5-6 (S), and 4 (O) PAH rings accounted for 54.5%, 68.7%, and 87.7%, respectively, along with naphthalene (SW), dibenzo(a,h)anthracene (S), and pyrene (O) as the prevailing compounds. PCA suggested the predominance of particular groups related to SW (LMW-PAH), S (HMW-PAH), and O (pyrene and fluoranthene). Furthermore, one sample of O presented a high PAH bioavailability as shown through the BAF, with emphasis on pyrene (BAF = 26.8). The RQ showed a low to moderate range in SW and S; hence, in-depth information about the possible toxic effect in organisms of this region is required.

A photobioreactor using Nannochloropsis oculata marine microalgae for removal of polycyclic aromatic hydrocarbons and sorption of metals in produced water

The objective of the present work is to evaluate the potential of the removal of PAHs and metal sorption for the treatment of petroleum produced water using a photobioreactor system with Nannochloropsis oculata microalgae. A set of photobioreactors with different gradients of produced water concentration diluted in saline water was designed, establishing five gradients (v/v): 0, 25, 50, 75 and 100%. These concentrations were established to test the removal of PAHs. The microalgal growth was monitored daily, noting the adaptation of microalgae to the addition of produced water as a culture medium, with cell growth of 5.24 × 10⁷ cells mL^-1 from 25% (v/v), 4.09 × 10⁷ cells mL^-1 from 50% (v/v), 2.77 × 10⁷ cells mL^-1 from 75% (v/v), and 1.17 × 10⁷ cells mL^-1 from 100%. The total removal efficiency of PAHs in the produced water was 94%. Organic compounds such as naphthalene, benzo(a)pyrene, benzo(b)fluoranthene, and acenaphthylene showed higher removal percentages, between 89 and 99% efficiency in produced water. Iron and zinc were the metals detected in the water produced, and iron reduced from 1.57 ± 0.08 mg L^-1 to <0.1 mg L^-1 after 28 days of cultivation, whereas zinc increased by 0.23 ± 0.05 to 3.90 ± 0.46 mg L^-1. The PAHs removal may have occurred in two ways, by intracellular bioaccumulation or biodegradation by oxidoreductase enzymes. 0.2 g of dry biomass with maximum extraction of oil obtained 3.07% and generation of 3.70% of protein was considered as value-added products for biodiesel and bioplastics.

Heart Failure and PAHs, OHPAHs, and Trace Elements Levels in Human Serum: Results from a Preliminary Pilot Study in Greek Population and the Possible Impact of Air Pollution

Cardiovascular diseases (CVDs) have been associated with environmental pollutants. The scope of this study is to assess any potential relation of polycyclic aromatic hydrocarbons (PAHs), their hydroxylated derivatives, and trace elements with heart failure via their direct determination in human serum of Greek citizens residing in different areas. Therefore, we analyzed 131 samples including cases (heart failure patients) and controls (healthy donors), and the respective demographic data were collected. Significantly higher concentrations (p < 0.05) were observed in cases' serum regarding most of the examined PAHs and their derivatives with phenanthrene, fluorene, and fluoranthene being the most abundant (median of >50 μg L-1). Among the examined trace elements, As, Cd, Cu, Hg, Ni, and Pb were measured at statistically higher concentrations (p < 0.05) in cases' samples, with only Cr being significantly higher in controls. The potential impact of environmental factors such as smoking and area of residence has been evaluated. Specific PAHs and trace elements could be possibly related with heart failure development. Atmospheric degradation and smoking habit appeared to have a significant impact on the analytes' serum concentrations. PCA-logistic regression analysis could possibly reveal common mechanisms among the analytes enhancing the hypothesis that they may pose a significant risk for CVD development.

Effects of Benzo[a]pyrene, Cortisol, and 17ß-Estradiol on Liver Microsomal EROD Activity of Anguilla anguilla: An In Vitro Approach

Fish liver ethoxyresorufin-O-deethylase (EROD) activity is widely used as biomarker of exposure to chemicals such as polycyclic aromatic hydrocarbons (PAHs). It is known that endocrine system plays a major role in fish stress mechanism. Despite the considerable scientific information about steroid hormone’s response, namely cortisol and 17ß-estradiol (E2), to stress situations, little is known about the influence of these hormones on enzymes involved on the biotransformation process. Thus, this study aimed to assess the in vitro effects of environmentally relevant concentrations of benzo[a]pyrene (B[a]P) (0.1, 0.3, 0.9, and 2.7 µM) and of two steroid hormones (cortisol and 17ß-estradiol) in a physiologically relevant concentration (5.997 ng/mL), alone or in combination, on Anguilla anguilla liver microsomal EROD activity, previously induced by 4 mg/kg β-naphthoflavone intraperitoneal injection. Hepatic microsomes in vitro exposure to the tested B[a]P concentrations induced a dose response inhibition of EROD activity, whereas exposure to cortisol significantly induced the activity of this enzyme. The steroid hormones were able to decrease the inhibitory effects of B[a]P on microsomal EROD activity, thus revealing a protective effect of these hormones over enzyme activity inhibited by contaminants.

Riverine transport and water-sediment exchange of polycyclic aromatic hydrocarbons (PAHs) along the middle-lower Yangtze River, China

We examined the riverine transport of polycyclic aromatic hydrocarbons (PAHs) based on their spatial-temporal distributions in water and sediments from the mainstream along the middle and lower Yangtze River. According to the fugacity fraction (ff) estimation, sediments performed as a secondary emission source of two-, three-, and four-ringed PAHs and as a sink for five- and six-ringed congeners, leading to higher ecological and human health risks especially towards the lower reaches. The higher PAH levels observed in the more developed delta and megacities were highly linked to economic parameters. This was further supported by the source apportionment performed using the principal component analysis-multiple linear regression (PCA-MLR) model, which showed major contributions of coal and coke combustions along with vehicle emissions. The spatial-temporal distribution revealed that water runoff was the major contribution to PAHs transport along the middle-lower Yangtze River, whereas a sharp decrease in sediment discharge due to the dam impoundment along the upper reaches would lead to an increase in the catchment retention effect of PAHs. Hence, the biogeochemical processes of PAHs and their impacts on the fragile ecosystems as a consequence of the further modification of the sedimentary system in rivers need to be fully explored.

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

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

Heavy metals and persistent organic pollutants contamination in river, estuary, and marine sediments from Atlantic Coast of Democratic Republic of the Congo

The pollution assessment and the evaluation of potential risks in the Atlantic Coastal Region of the Democratic Republic of the Congo are still very limited. Consequently, the present study investigates for the first time the concentrations of heavy metals and persistent organic pollutants (organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs)) in river, estuary, and marine sediments from this area. The results highlighted high concentrations of Cr, Zn, As, and Pb exceeding the probable effect level (PEL) on aquatic life. Zn was the most dominant element detected at a range of 180-480 mg kg^-1 in marine sediment, 132-382 mg kg^-1 in estuary sediment, and 121-687 mg kg^-1 in river sediment. Total PCBs (∑7 × 4.3) ranged from 1995 to 20,156 μg kg^-1, 2013-12,058 μg kg^-1, and 1861-36,417 μg kg^-1 in marine, estuary, and river sediments, respectively. Total PCBs (∑7 × 4.3) were above PEL for all sediments, suggesting potential adverse effects on benthic organisms. The OCP, PBDE, and PAH levels were low to moderate for all sediments. Taking into consideration, the concentrations of Zn, Pb, PCBs, and DDTs, probable environmental risks, are present.

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

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

Ecological risk assessment of petroleum hydrocarbons on aquatic organisms based on multisource data

From the perspective of ecological risk, this study uses a multisource data method to search for global data, uses the acute and chronic ratio method to process the data, uses the species-sensitive distribution method to evaluate the ecological risk that petroleum hydrocarbons pose to aquatic organisms, and evaluates the ecological risk of the water environment in five Chinese water bodies. The results are as follows. First, in an aquatic ecosystem, the toxicological effects of petroleum hydrocarbons were found to be more obvious on consumers, and the sensitivity of fish was found to be higher than that of crustaceans. Second, the acutely lethal effects of petroleum hydrocarbons, fluorene, and benzo [a] pyrene on aquatic ecosystems were fitted by using the documentary method of multisource data collection and a Log-logistic curve. Third, in the case study evaluation of five Chinese water bodies, the ecological risks of polycyclic aromatic hydrocarbons were ranked (from low to high) as fluorene < benzo [a] pyrene. The ecological risk values of benzo [a] pyrene were all greater than 1. These risks should not be underestimated, and prevention and control work should be performed.

Research on Land Use Changes and Ecological Risk Assessment in Yongjiang River Basin in Zhejiang Province, China

Studying land use changes and ecological risk assessment in Yongjiang River Basin in Zhejiang Province, China, provides theoretical references for optimal configuration of land resources and maintaining stability of ecosystems. Given impacts of land use changes on landscape patterns in the Yongjiang River Basin, ecological risk assessment indexes were constructed and used to analyze temporal and spatial variation characteristics of ecological risk within different periods. Results show that (1) the construction land area was increased quickly, while the cultivated area decreased sharply. A prominent characteristic of land use changes was manifested by transforming cultivated area and forestland into construction land. The utilized degree of the land increased continuously. Spatially, the land utilized degree in northern regions was higher than that in southern regions and the degree in eastern regions was higher than that in western regions. (2) The ecological risk in the Yongjiang River Basin was intensified and the area of high ecological risk was expanded by 893.96 km2. Regions with low and relatively low ecological risks concentrated in western and southern regions of the Basin, whereas regions with high ecological risks were mainly in northern and eastern regions. Landscapes in cities and towns at a high economic development level are highly sensitive to human activities. (3) Transformation of ecological risk is complicated. Land area with the ecological risk changing from a low level to a high level was 4.15 times that with the ecological risk changing from a high level to a low level. There were 15 transformation directions among different ecological risk regions.

Characterization, source identification and risk associated with polyaromatic and chlorinated organic contaminants (PAHs, PCBs, PCBzs and OCPs) in the surface sediments of Hooghly estuary, India

The spatial distribution, source identification and ecotoxicological impact of a group of persistent organic pollutants (POPs: dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexanes (HCHs), polychlorobiphenyls (PCBs), polychlorobenzenes (PCBzs)), and polyaromatic hydrocarbons (PAHs) were investigated in surface sediment samples (0-5 cm, <63 μm grain size) along the ecologically stressed Hooghly River estuary, East India. The results demonstrated a wide range of concentrations (ng/g dry weight) with the following decreasing order: ∑₁₆PAHs (3.3-630) > ∑₆DDTs (0.14-18.6) > ∑₇PCBs (0.28-7.7) > ∑₂PCBzs (0.01-1.3) > ∑₅HCH (0.10-0.6), with a dominance of p,p'-DDT and higher molecular weight PAHs. Selected diagnostic ratios indicated a mixture of both pyrolytic and petrogenic sources of PAHs, inputs of weathered DDT and their degradation in oxidizing environment, and a predominance of industrial input over the agricultural wastes. The cumulative impact of the pollutants (effective range medium quotient (ERMq): 0.01-0.16) reflected minimal to low ecotoxicological risk, with highest probability of toxic effects towards surrounding biota at Barrackpore (21%). ∑₆DDTs exceeded the effect range low value resulting occasional adverse impact to the sediment dwelling organisms. Among the PAHs, the 4-ringed compounds accounted for 68% of the PAHs. Further, carcinogenic PAHs (BaA, Chry, BbF, BkF, BaP, DahP, Inp) possessed highest cancer risk (CR = 2.09 × 10^-3) to the local population when exposed to the sediments from the studied area and ingestion was found to be the primary process of contamination. The study strongly recommends a systematic monitoring of POPs and PAHs, being the Hooghly River water used by local people for their livelihood.

Spatio-temporal distribution and sources identifications of polycyclic aromatic hydrocarbons and their alkyl homolog in surface sediments in the central Arabian Gulf

The quantitative analysis of 18 parents and their alkyl homologs was performed in sediment samples from the central Arabian Gulf (Gulf) around Qatar Peninsula in six sequential seasons, winter 2014 to spring 2015, at 21 locations with a water depth range of 1.5-60 m. PAHs distribution was patchy with higher concentrations found inside semi-enclosed coastal areas like harbors and bays. The mean PAHs concentration was 112 ng·g^-1 dry weight with a range of 0.6 to 1560 ng·g^-1 and a variability coefficient of 2.4. The PAHs mean concentration was highest in the winter by a factor of 5 compared to mean summer concentration. A significant seasonal variability in the concentrations of ∑PAHs is mainly attributed to variability in the concentrations of the low molecular weight PAHs fraction and the less alkylated PAHs. Alkylated-PAHs were the most dominant PAHs comprising about 50% of the ∑PAHs, and with about 6 times higher than the mean concentrations in the winter compared to the mean summer concentration. The LPAHs concentrations correlated negatively with temperature and ∑PAHs correlated positively with % clay. Principal component analysis was used to identify sources of PAHs. PAHs in the Gulf have mixed sources with an estimated 57% from petroleum and 43% from pyrogenic sources. Coastal water hydrodynamics and lateral transport processes affect the distribution and composition of PAHs in the central Gulf.

Occurrence and Toxicological Risk Assessment of Polycyclic Aromatic Hydrocarbons and Heavy Metals in Drinking Water Resources of Southern China

Polycyclic aromatic hydrocarbons (PAHs) and heavy metals exposure is related to a variety of diseases and cancer development, posing a great health risk to humans. In this study, water samples were collected from nine important water sources in Guangdong, Guangxi and Hainan provinces to determine the degree of PAHs and heavy metals contamination. Overall, the total contents of 16 PAHs and heavy metals were found within the permissible levels. In human health risk assessment, the benzo(a)pyrene equivalent concentration (BaP_eq) presented a much lower level than the guideline values announced by Chinese Environmental Protection Agency (CEPA) and United States Environmental Protection Agency (US EPA), demonstrating that the PAHs contamination level in drinking water was mostly acceptable. For heavy metals, the Chronic daily intake (CDI), hazard quotient (HQ) or hazard index (HI) suggested that the water quality in nine water sources was desirable and did not present a risk to human health.