Contamination Of Marine Environment Research Articles

A Screening-Level Human Health Risk Assessment for Microplastics and Organic Contaminants in Near-Shore Marine Environments in American Samoa

Solid waste disposal is a growing concern among Pacific Island nations. With severe limitations in land area, in combination with the lack of reuse or recycling options, many near-shore marine ecosystems across Oceania are highly impacted by locally derived marine debris, including plastics, microplastics and associated chemical contaminants. In order to catalyze improved solid waste management and plastic use policies, the potential ecological and public health risks must be clearly identified and communicated. Using an ecological risk assessment framework, potential risks to marine ecosystems and human health are explored by quantifying microplastics and organic contaminants in 4 study sites located in Tutuila, American Samoa. Results of sampled near-shore marine waters, marine sediments and molluscs indicate that microplastics are unevenly distributed in the marine environment, with the highest concentrations detected in marine molluscs. These invertebrates also have the highest environmental concentrations of organic contaminants, including phthalates, pesticides and PCBs. However, based on estimated invertebrate consumption rates, the risk of adverse impacts to human health is likely to be low. Regardless, future studies are recommended to better understand the environmental partitioning of microplastics in dynamic near-shore marine environments, as well as the specific pathways and consequences of the physical and chemical impacts of microplastics on marine species populations and overall marine ecosystem health.

Polybrominated diphenyl ethers exert genotoxic effects in pantropic spotted dolphin fibroblast cell lines.

Cetaceans accumulate persistent and toxic substances such as polybrominated diphenyl ethers in their tissue. PBDEs are ubiquitous in marine environments, and their exposure to mammals is linked to numerous health effects such as endocrine disruption, neurotoxicity, carcinogenicity, and fetal toxicity. However, the toxicological effects and mechanism of toxicity in cetaceans remains poorly understood. The effects of BDE-47 (0.1-0.5μgmL-1), BDE-100 (0.1-0.5μgmL-1), and BDE-209 (0.25-1.0μgmL-1) exposure on cell viability, oxidative stress, mitochondrial structure, and apoptosis were evaluated using a recently established pantropical spotted dolphin (Stenella attenuata) skin fibroblast cell line (PSD-LWHT) as an invitro model. However, the production of reactive oxygen species (ROS) increased following exposure to 1.0μgmL-1 PBDE while superoxide anion, hydroxyl radicals, and inducible nitric oxide increased in a dose-dependent manner. At 0.5-1.0μgmL-1, PBDEs significantly reduced the mitochondrial membrane potential. In addition, exposure to BDE-47 and -209 significantly affected mitochondrial structure as well as cell signaling and transduction compared to BDE-100. Although PBDE exposure did not affect cell viability, a significant increase in cell apoptosis markers (Bcl2 and caspase-9) was observed. This study demonstrated that BDE-47, -100, and-209 congeners might cause cytotoxic and genotoxic effects as they play a crucial role in the dysregulation of oxidative stress and alteration of mitochondrial and cell membrane structure and activity in the fibroblast cells. Hence, these results suggest that PBDEs might have adverse health effects on cetaceans inhabiting contaminated marine environments.

Prescribing sea water quality criteria for arsenic, cadmium and lead through species sensitivity distribution

Water quality standards are essential for regulation of contaminants in marine environment. Seawater quality criteria (SWQC) for arsenic (As), cadmium (Cd) and lead (Pb) have not been developed for India. The aim of this study is to derive the SWQC for the metals based on Species Sensitivity Distribution (SSD). Eight species of sensitive marine organisms belonging to five phyla were assessed for their sensitivity to toxicity of As, Cd and Pb. Median effective concentrations (EC50) and Median Lethal Concentrations (LC50) were derived from the acute toxicity bio-assays. No Observed Effect Concentrations (NOEC), Lowest Observed Effect Concentrations (LOEC) and chronic values were derived from chronic toxicity bio-assays. Diatoms were more sensitive to As with 96 h EC50 of 0.1 mg/l and copepods were more sensitive to Cd and Pb with 96 h EC50 of 0.019 mg/l and 0.05 mg/l respectively. Estimated NOECs ranged from 4.87 to 21.55 µg/l of As, 1.0 to 120 µg/l of Cd and 5.67 to 91.67 µg/l of Pb. Similarly, chronic values (µg/l) were in the range of 6.71–26.1, 1.38–170, and 7.67–91.67 of As, Cd and Pb respectively. The Criterion Maximum Concentration (CMC), Criterion Continuous Concentration (CCC) and Predicted No Effect Concentration (PNEC) values were prescribed as SWQC. The CMC (µg/l) of 19, 1.7 and 17 for As, Cd, and Pb were derived respectively for acute exposure during accidental marine outfalls. The CCC (µg/l) for As was 4.6, 1.1 for Cd and 5.9 for Pb are recommended as SWQC for protection of 95% of marine organisms. PNEC (µg/l) of 3.8 for As, 0.92 for Cd and 4.3 for Pb are suggested for highly disturbed ecosystems, shell fishing and mariculture uses of water bodies. These values are recommended as a baseline for site specific water quality criteria for the coastal waters of the country.

Preferential transport of microplastics by wind

Contamination of terrestrial and marine environments by plastic waste has been widely documented. Most research into the distribution of microplastics has focused on water but here we show that wind transport can be very effective in mobilising microplastic particles. A series of wind tunnel experiments using two different substrates (sand and soil), two different microplastics (microbeads and fibres) and 5 different concentrations of microplastics (ranging from 0 mg kg−1dw to 1040 mg kg−1dw) is used to demonstrate that microplastics are preferentially transported by wind compared to sand and soil. When compared to either of the untreated substrate beds (0 mg kg−1dw), the inclusion of microplastics was not found to significantly affect the wind erosion threshold for any of the concentrations or geometric forms (fibres or beads) tested. Averaged over all concentrations of microplastics and both substrate types, microplastic enrichment was lower for microbeads than fibres. The enrichment of microplastic fibres within the entrained particulate matter was one to two orders of magnitude higher for both test bed substrates, ranging from 98 to 498 for the sand and 278 to 726 for the soil. This suggests microplastic shape needs to be carefully parameterized in models of atmospheric microplastic transport. We suggest that microplastic research could benefit from previous investigations into the wind erosion of soil organic carbon.

Cadmium adsorption to clay-microbe aggregates: Implications for marine heavy metals cycling

Interactions between microorganisms and clay minerals influence the transport and cycling of metal contaminants in both marine and terrestrial environments. The present study was conducted to quantify the adsorption of dissolved cadmium, Cd(II), under seawater-like conditions to the marine cyanobacterium Synechococcus sp. PCC 7002, three common clay minerals (kaolinite, montmorillonite and illite), as well as cell-clay aggregates. We show here that the Synechococcus-only experiments removed the most Cd above pH 5.5, followed in decreasing order by aggregates of 50% cells:50% individual clays, aggregates of cells and all 3 clays, and individual clays. Electron microscope imaging showed that clays associated in a tangential edge-on orientation to the cells in Synechococcus-clay mineral aggregates. A non-electrostatic surface complexation modeling approach was used to fit Cd adsorption onto Synechococcus cells and individual clay minerals. The resulting Cd binding constants were then used in consort with surface functional group pKa values and site concentrations to accurately predict the extent of Cd adsorption onto the Synechococcus-clay mineral aggregates using the component additivity (CA) approach. We observed that the addition of cyanobacterial cells to clay mineral suspensions led to significantly larger mean aggregate sizes of clay minerals, enhancing the clay sedimentation rate. Although specifically focused on Cd, our study indicates that the ratio of bacterial plankton to clay minerals is an important determinant in terms of understanding the rate with which metals are transferred from the water column to the seafloor.

Organic pollutants in sedimentary microplastics from eastern Guangdong: Spatial distribution and source identification.

Microplastics have a strong affinity for potentially toxic organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs). Since 2005, the International Pellet Watch used plastic pellets to monitor hydrophobic organic contaminants in marine environments. We examined the spatial distribution and sources of 16 PAHs and eight OCPs on microplastics (pellets, fragments, and foam) collected from eastern Guangdong beaches with the goal of evaluating the feasibility of exclusively using pellets in global monitoring of hydrophobic organic contaminants. The ∑PAH and ∑OCP concentrations ranged from 11.2 to 7710ngg-1 and 2.2-1970ngg-1, respectively. Although inter-site and regional differences were insignificant in fragments and foam, regional differences were observed in ∑OCP concentrations on pellets samples collected at the estuary mouth and the distributary (p<0.05). No regional difference in ∑PAH concentration on microplastics was observed, except between fragments from the remote beach and those from the distributary (p=0.015) and the estuary mouth (p=0.015). The compositional profiles of PAHs revealed that PAHs with 2-4 rings were more dominant than those with >4 rings. Considering low molecular weight PAHs are less hydrophobic and more toxic; the results suggest low molecular weight PAHs may pose a significant risk to marine organisms. This study shows that the International Pellet Watch could offer critical data on source and transport of microplastic-associated OCPs but may overlook critical vehicles of PAHs in coastal environments such as foam.

Impact of historical contamination on meiofaunal assemblages: The case study of the Bagnoli-Coroglio Bay (southern Tyrrhenian Sea)

The effects of contaminants on marine organisms have been documented since decades, but the long-term responses and recovery rates of benthic communities to mixtures of contaminants, several years after the cessation of industrial activities, need to be further investigated. Bagnoli-Coroglio Bay (Gulf of Naples, Tyrrhenian Sea) is a typical example of historically contaminated coastal area due to industrial activities stopped at the beginning of nineties. In the present study we carried out a fine spatial scale analysis of the distribution of meiofaunal (and nematodes) assemblages along five bathymetric transects located at increasing distance from the historical source of contamination in relation with the polycyclic aromatic hydrocarbon and heavy metal concentrations present in the sediment. Meiofaunal abundance and biomass changed widely along transects but independent from the distance from the source of contamination. Even when the contamination levels were expected to induce significant detrimental biological consequences, meiofaunal abundance and biomass were similar to those reported in unpolluted benthic coastal areas worldwide. Conversely, biodiversity in terms of meiofaunal taxa richness was generally low (range: 5–8 taxa in 12 of the overall 15 stations investigated). This was explained by the lack of sensitive groups such as ostracods, gastrotrichs and tardigrades commonly encountered in benthic coastal ecosystems, thus reflecting an overall poor/moderate environmental quality of the investigated area. Nematode (structural and functional) diversity was also low, particularly at stations characterized by higher contamination levels. At the same time, nematode species composition did not change significantly among stations suggesting a widespread effect of contaminants able to reduce the variability (i.e., turnover diversity) within the assemblages of the whole study area. Overall, our results indicate that even decades after the cessation of contaminant emissions, benthic biodiversity was affected in terms of both meiofaunal taxa and nematode species. These findings strongly reinforce the call for reducing sources of chronic pollution in marine ecosystems and provide new insights for a better understanding of the ecological recovery of historically contaminated marine environments.

For a new plastics economy in agriculture: Policy reflections on the EU strategy from a local perspective

Plastic production and consumption around the world have seen a rapid increase since the end of World War II, with an expected peak in the next 20 years. Agriculture is among the causes of this due to its intensive farming practices and the use of various plastic materials. This produces both advantages (e.g. yield increase, early harvest, reduced use of chemicals) and disadvantages. The disadvantages are particularly related to a plastic waste management problem, from which the contamination of terrestrial, marine and air environments with severe consequences on food security and human health also derive. With the 2018 European Strategy for Plastics in a Circular Economy, the European Commission (EC) identifies a set of actions to reduce plastic pollution in the decades ahead. For the actual implementation of this strategic vision, however, innovative investment and appropriate policy tools need to be identified. This paper attempts to understand the acceptability of some ad-hoc policy tools among farmers by investigating their attitudes towards the application of subsidies, tax-credits and pay-back (this latter under an Extended Producer Responsibility (EPR) scheme) to abate agricultural plastic pollution with the aim of making this sector cleaner and more oriented to the implementation of the sustainability principles. While referring to the territory of the province of Foggia in southern Italy as a case study, we analyse the preferences expressed by 1,783 farmers by using a multinomial logistic regression. Key results suggest that large agricultural farms would favour the adoption of tax-credits. In contrast, small farms would consider more favourable the introduction of a pay-back tool to incentivize their contribution to plastic pollution abatement. The significance of the obtained results is twofold. First, farm size is a key element towards a differentiation of policy tools to adopt for plastic waste management in agriculture. Second, the differentiation of the above policy tools according to the farm dimension would lead to a cost-effectiveness management of agricultural plastic waste.

No evidence of microplastic consumption by the copepod, Temora longicornis (Müller, 1785) in Chichester Harbour, United Kingdom

Abstract Increasing global concern with respect to the levels of bioavailable microplastic (<5 mm) contamination in marine environments has led to many studies examining the physiological impacts of microplastic consumption on a range of species. The copepod, Temora longicornis (Muller, 1785), is a common inhabitant of the upper epipelagic zone of gulf and estuarine waters of the North Atlantic which we hypothesised would be regularly exposed to microplastic contaminated marine environments. They are therefore at risk of consumption of microplastic pollutants, which could have wider trophic impacts. Microplastic was recorded in all water samples with an average concentration of 8.2 particles/m3. However, there was no significant difference in abundance or size of microplastics sampled from three localities within Chichester Harbour, UK. Individual digestion of ninety copepods found no evidence of consumption of any microplastic contaminants above our observable size range of 23 μm. Whilst microplastic pollution remains of wider ecological concern, our results suggest limited support for the potential for this copepod species to transfer these pollutants to higher trophic levels.

Highly efficient and reusable superhydrophobic/superoleophilic polystyrene@ Fe3O4 nanofiber membrane for high-performance oil/water separation

Due to increasing of oil spills and high organic contamination of marine environment, developing of cost-effective and rapid oil/water separation technique has become inevitable. Herein, freestanding and flexible hybrid polystyrene nanofibers are introduced as highly efficient hybrid membrane for ultrafast oil/water separation without external pressure. Typically, different loading of Fe3O4 nanoparticles embedded into polystyrene nanofibers using electrospinning to fabricate superhydrophobic/super-oleophilic membrane. The morphological shape, crystal structure and surface wettability behavior were elucidated by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and contact angel, respectively. The optimum loading of magnetite nanoparticles into the nanofiber membranes was investigated to achieve best separation performance. The obtained results demonstrated that the incorporation of (Fe3O4) nanoparticles into membrane has a significant impact for enhancing superhydrophobic properties and the separation efficiency against light and heavy oils. Among all formulations, the fabricated (PS@Fe3O410 wt.%) membrane revealed ultrahigh flux (5000 L m−2 h−1) with separation efficiency of 99.8 % for hexane under gravity driven process and excellent superhydrophobicity with water contact angle 162° moreover excellent reusability 98.5 % for 50 consecutive cycles. Interestingly, the proposed hybrid nanofiber membrane achieved distinct separation efficiencies 95 % and 92 % for food oils such as olive oil and sesame oil. Overall, the current study provides cost-effective and facile approach to distinctly improve the membrane performance for durable oil/water separation technique.

An improved rapid analytical method for the arsenic speciation analysis of marine environmental samples using high-performance liquid chromatography/inductively coupled plasma mass spectrometry.

Arsenic contamination in marine environments is a serious issue because some arsenicals are very toxic, increasing the health risks associated with the consumption of marine products. This study describes the development of an improved rapid method for the quantification of arsenic species, including arsenite (AsIII), arsenate (AsV), arsenocholine (AsC), arsenobetaine (AsB), dimethylarsinic acid (DMA), and monomethyl arsonic acid (MMA), in seaweed, sediment, and seawater samples using high-performance liquid chromatography/inductively coupled plasma-mass spectrometry (HPLC/ICP-MS). ICP-MS based on dynamic reaction cells was used to eliminate spectral interference. Ammonium nitrate- and phosphate-based eluents were used as the mobile phases for HPLC analysis, leading to shorter overall retention time (6 min) and improved peak separation. Arsenicals were extracted with a 1% HNO3 solution that required no clean-up process and exhibited reasonable sensitivity and peak resolution. The optimized method was verified by applying it to hijiki seaweed certified reference material (CRM, NMIJ 7405-a) and to spiked blank samples of sediment and seawater. The proposed method measured the concentration of AsV in the CRM as 9.6 ± 0.6 μg/kg dry weight (dw), which is close to the certified concentration (10.1 ± 0.5 μg/kg dw). The recovery of the six arsenicals was 87-113% for the sediment and 99-101% for the seawater. In the analysis of real samples, AsV was the most abundant arsenical in hijiki and gulfweed, whereas AsB was dominant in other seaweed species. The two inorganic arsenicals (AsIII and AsV) and AsV were the most dominant in the sediment and seawater samples, respectively.

The Effects of Selected Heavy Metal Elements (arsenic, Cadmium, Nickel, Zinc) On Experimentally Grown Foraminiferal Assemblages from Sapelo Island, Georgia and Little Duck Key, Florida, U.S.A.

Abstract Benthic foraminifera are valuable environmental indicators of heavy metal contaminants in marine environments. To broaden their effectiveness as bioindicators, this study compares individually the effects of selected heavy metal contaminants, including both metabolically essential and non-essential elements, on temperate rotalids and subtropical miliolids, as well as associated monothalamid foraminifera. To accomplish these aims, assemblages of foraminifera were grown experimentally from propagules (small juveniles) collected from two coastal sites: Sapelo Island, Georgia, and Little Duck Key, Florida, that provide an effective comparison between environments and types of foraminifera. Surface sediment was collected from both locations and sieved immediately after collection. Using the propagule method, assemblages of foraminifera were grown in the laboratory from propagules in the sediment samples. Two metabolically essential trace elements, nickel, and zinc, and two non-essential elements, arsenic and cadmium were used to represent both types of heavy metal. Experimental conditions were held constant while varying only the metal concentrations. In treatments from both origins, increasing concentrations of cadmium, nickel, and zinc led to decreases in abundance and diversity for the foraminifera. In addition, zinc, and to a lesser extent cadmium and nickel above certain concentrations, resulted in an increase of deformed tests among the foraminifera. Deformities occurred amongst the most common calcareous species from Sapelo island: Ammonia tepida and Haynesina germanica. Fewer deformities were observed in common calcareous species from Little Duck Key, the miliolids Quinqueloculina sabulosa and Quinqueloculina bosciana featured few deformities. Notably, monothalamid species such as Psammophaga sapela remained present at high metal concentrations. These results support previous research and reinforce the usefulness of rotalids such as A. tepida and H. germanica as bioindicators of heavy metal contamination as well as suggesting a possible use of monothalamids such as P. sapela in this manner.

Arctic cleansing diet: Sex-specific variation in the rapid elimination of contaminants by the world's champion migrant, the Arctic tern

Contamination of Arctic marine environments continues to be a concern for wildlife managers. Because the Arctic is a sink for the long-range transport of persistent organic pollutants (POPs), many studies have detected high concentrations of POPs in various Arctic birds. In this study from high Arctic Canada, we show that male Arctic terns (Sterna paradisaea), which migrate from the Antarctic to the Arctic annually to breed, decline in concentrations of many hepatic POPs through the breeding season. This suggests that local Arctic food webs are less contaminated than regions where terns fed during or migration, despite that the terns appear to feed at a higher trophic level near their colony.

Occurrence and spatial distribution of antibiotic resistance genes in the Bohai Sea and Yellow Sea areas, China

Rapid development of Bohai and Yellow Sea Economic Rim has led to the concern of emerging contamination of marine environments. This study investigated the spatial distribution of antibiotic resistance genes (ARGs) in Bohai and Yellow Sea areas. A large scale sampling from Bohai Sea, Yellow Sea and the major cities along the coastline from the mouth of Yalu River to the Yangtze River was performed. The spatial distribution of target ARGs based on the absolute abundances was in the trend of river water ≈ coastal water > the Bohai Sea > the Yellow Sea, inshore > offshore and inner bay > bay mouth. The total absolute abundances of selected ARGs in the coastal waters (1.23 × 104–3.94 × 105 copies/mL) were about 1–4 orders of magnitude higher than those in the sea (21.1–8.00 × 103 copies/mL). The abundances of ARGs fluctuated greatly in the Yellow Sea and the coastal areas. Sulfonamide resistance genes hold the highest abundances in the Bohai and Yellow Sea (up to 2.13 × 103 copies/mL of sul1 and 6.23 × 103 copies/mL of sul2), followed by tetracycline and quinolone resistance genes, while qnrA hold the highest abundances in coastal areas (up to 3.66 × 105 copies/mL). The distribution coefficients of target genes between sediments and corresponding water samples were more than 1.0 in the majority of different aquatic systems. According to the principle component analysis and redundancy analysis, water samples collected from the sea clustered together while those from the coastal zone and rivers were separated. Ammonium and nitrate played important roles in the distribution and variation of ARGs. Co-occurrence network analysis revealed that the potential multi-antibiotics resistant bacteria were detected with higher abundances in the Yellow Sea than in the Bohai Sea. These observations provided a comprehensive new insight into the pollution status of ARGs in the Bohai and Yellow Sea areas.

Culturable hydrocarbonoclastic marine bacterial isolates from Indonesian seawater in the Lombok Strait and Indian Ocean

PurposeThe study aims to isolate the culturable marine bacteria and to assess their potential as the bioremediation agent for petroleum hydrocarbons contamination in marine environment. MethodsBacteria isolates were obtained by repetitive streaks to obtain purified bacteria on Zobell marine agar plates before further analysis and culture through direct visualization on agar plates. Identification were conducted using 16S rDNA sequence which are compared using NCBI BLAST and, combined with phenotypic and phylogenetic data. The potential use of the selected bacteria was tested by culturing them with two carbon sources i.e., glucose and crude oil. ResultFifty-one culturable marine hydrocarbonoclastic bacteria were isolated from the Lombok Strait (LS-3, LS-13, LS-14, LS-15, LS-16 and LS-20) and Indian Ocean (IO-1, IO-6, IO-8, IO-19, IO-24 and IO-25). Twelve isolates were found to degrade crude oil efficiently at a >2% concentration and to grow with crude oil as their sole carbon and energy source. These 12 strains belong to the genus Bacillus, which is well known to produce surface active agents, and the oil displacement assay indicated the production of these agents by these strains. Within the genera Bacillus, five species (Bacillus flexus, B. methylotrophicus, B. aquimaris, B. horikoshii, and B. thioparans) were represented by the 12 identified strains. ConclusionSelected strains from the Lombok Strait and Indian Ocean were capable of degrading crude oil (2% v/v) by 43.9–71.9% over 14 days. These results are important for marine bioremediation in Indonesia, which often faces risks of oil spill contamination and disaster.

Aromatic Hydrocarbons Degradation and Plasmid Profile of Marine Bacterial Isolates Obtained from Petroleum Contaminated Marine Environments of Niger Delta Nigeria

Aims: To determine the aromatic hydrocarbons degradability and plasmid profile of the marine bacteria isolated from Rivers State contaminated marine environments of Niger Delta.&#x0D; Study Design: Nine treatments and the controls designs were set up in triplicates containing 100 mL of sterile modified mineral basal medium in 500 mL conical flasks supplemented with 1 mg /L of xylene, anthracene and pyrene each; nine marine hydrocarbon degraders and incubated at 24 ºC for 24 days study. The nine treatments and control set ups designated as ANT1, XYL2, PYR3, ANT4, PYR5, ANT6, XYL7, XYL8, PYR9 and CTRL (Without hydrocarbons) were used to determine the aromatic hydrocarbons degradability and plasmid profile of the marine bacteria. &#x0D; Place and Duration of Study: Department of Environmental Sciences, University of South Africa, Pretoria, South Africa between September, 2015 and March, 2018.&#x0D; Methodology: A laboratory scale study was carried on six composite samples of the sediment and water samples from the three studied areas using enrichment, screening, selection, morphological, biochemical, degradation and plasmid assays.&#x0D; Results: The findings revealed that the three sampling sites harbour a lot of efficient aromatic degrading bacterial strains belonging to the genera: Providencia, Alcaligenes, Brevundimonas, Myroides, Serratia, and Bacillus able to significantly (P = .05) tolerate and grow on the aromatic hydrocarbons. The bacterial strains especially Serratia marcescens XYL7 significantly (P = .05) removed 99.50 ± 0.05 % and 60.00 ± 0.02 % in weights of xylene and pyrene, respectively while Alcaligenes faecalis PYR5 significantly (P =.05) degraded 97.40 ± 0.01 % in weight of anthracene. The degradations of the respective hydrocarbons were found to be plasmid mediated with plasmid sizes between 200 bp - 1.2 kbp.&#x0D; Conclusion: Thus, the excellent degradative abilities of these bacterial strains especially Serratia marcescens XYL7 could be exploited for bioremediation purposes in Nigeria.

Phylogenetic Framework and Metabolic Genes Expression Analysis of Bacteria Isolated from Contaminated Marine Environments of Niger Delta

Aims: To explore the phylogenetic framework of bacteria isolated from contaminated marine environments of Niger Delta and the expression of the metabolic genes coding for aromatic hydrocarbon degradation and surfactant production.&#x0D; Study Design: Nine treatments designs were set up in triplicates containing 25 mL of sterile modified mineral basal medium supplemented with nine marine hydrocarbon degraders incubated at 24°C for 5 days. Three of the set ups were supplemented each with 1 mg /L of xylene, anthracene and pyrene.&#x0D; Place and Duration of Study: Department of Environmental Sciences, University of South Africa, Pretoria, South Africa between September, 2015 to December, 2017.&#x0D; Methodology: A laboratory scale study was carried on six composite samples of the sediment and water samples from the three studied areas using enrichment, screening, selection, characterization, and PCR assays to explore the phylogenetic framework and metabolic genes expression of the marine bacteria for aromatic hydrocarbon degradation and surfactant production.&#x0D; Results: The findings revealed that there was significant abundance of THB (P = .05) more than TCHUB and more xylene degraders than anthracene and pyrene degraders in the sediment and water samples respectively. The phylogenetic correlational analysis revealed that all the nine selected best degraders out of 48 isolates from the studied area were evolutionary related belonging to the genera: Providencia, Alcaligenes, Brevundimonas, Myroides, Serratia, and Bacillus; able to significantly (P = .05) utilize the all the aromatic hydrocarbons. The existence of catabolic and surfactant genes namely catechol dioxygenase (C23O), rhamnolipid enzyme (rhlB) and surfactin /lichenysin enzyme (SrfA3 /LicA3) genes were detected in only four (4) out of the nine (9) marine aromatic degrading bacteria with 881 base pairs sizes.&#x0D; Conclusion: Thus, the study revealed that these bacterial strains especially Serratia marcescens XYL7 might possess metabolic genes for in situ aromatic hydrocarbon degradation and surfactant production.

In vitro Degradation and Reduction of Aromatic Hydrocarbons by Marine Bacteria Isolated from Contaminated Marine Environments of Niger Delta

Aims: To determine the in vitro degradation and reduction of aromatic hydrocarbons by marine bacteria isolated from contaminated marine environments of Niger Delta.&#x0D; Study Design: Nine treatments and nine controls designs were set up in triplicates containing 100 mL of sterile modified mineral basal medium in 500 mL conical flasks supplemented with 1 mg /L of xylene, anthracene and pyrene each; nine marine hydrocarbon degraders and incubated at 24 ºC for 24 days study. The nine treatments and control set ups designated as ANT1, XYL2, PYR3, ANT4, PYR5, ANT6, XYL7, XYL8, PYR9 and CTRL (Without hydrocarbons) were used to determine the aromatic hydrocarbons degradability and reduction by the marine bacteria. &#x0D; Place and Duration of Study: The studied sites were Abonema Wharf Water Front in Akuku-Toru Local Government Area, Nembe Water-Side in Port Harcourt Local Government Area and Onne Light Flow Terminal Seaport located in Eleme Local Government Area of Rivers State, Nigeria between September, 2014 and March, 2017.&#x0D; Methodology: A laboratory scale study was carried on six composite samples of the sediment and water samples from the three studied areas using enrichment, screening, phenotypical, degradation and TLC techniques.&#x0D; Results: The results showed that the three studied areas harbour numerous promising aromatic degrading bacterial strains belonging to the genera: Providencia, Alcaligenes, Brevundimonas, Myroides, Serratia, and Bacillus. The bacterial strains especially Serratia marcescens XYL7 significantly (P = .05) had 99.50 ± 0.05 % and 60.00 ± 0.02 % degradations in weights of xylene and pyrene, respectively while Alcaligenes faecalis PYR5 significantly (P =.05) degraded 97.40 ± 0.01 % in weight of anthracene. TLC result revealed evidences of large spots size reductions or losses of test samples compare to control samples with minor spot sizes.&#x0D; Conclusion: Thus, the outstanding degradative abilities of these strains could be exploited in bioremediation campaigns in Nigeria.

Biofilm and Biosurfactant Mediated Aromatic Hydrocarbons Degradation by Marine Bacteria Isolated from Contaminated Marine Environments of Niger Delta

Aims: To examine the effects of biofilm and biosurfactant associated cells of marine bacteria isolated from contaminated marine environments of Niger Delta on aromatic hydrocarbon degradation.&#x0D; Study Design: Nine treatments and the controls designs were set up in triplicates containing 100 mL of sterile modified mineral basal medium in 250 mL conical flasks supplemented with 50, 100, 200 and 300 ppm of xylene, anthracene and pyrene each and nine marine hydrocarbon degraders; incubated at 24°C for 5 - 7 days. The nine treatments and control set ups designated as ANT1, XYL2, PYR3, ANT4, PYR5, ANT6, XYL7, XYL8, PYR9 and CTRL (without hydrocarbons) were used to examine the effects of biofilm and biosurfactant produced by the marine bacteria on aromatic hydrocarbon degradability.&#x0D; Place and Duration of Study: Department of Microbiology, Chukwuemeka Odumegwu Ojukwu University, Uli Nigeria between September, 2014 and August, 2017.&#x0D; Methodology: A laboratory scale study was carried on six composite samples of the sediment and water samples from the three studied areas using enrichment, selection, morphological, biochemical, growth effect, emulsification, surface tension, bacterial adherence to hydrocarbon (BATH), salt aggregation (SAT) and microtitre plate biofilm formation tests.&#x0D; Results: The findings revealed that the three sampling sites harbour a lot of efficient aromatic degrading bacterial strains belonging to the genera: Providencia, Alcaligenes, Brevundimonas, Myroides, Serratia, and Bacillus able to significantly (P = .05) degrade the aromatic hydrocarbons. Significant positive correlation between biofilm formation and emulsification activity (r = 0.670; P = .05), was observed while surface tension (r = 0.134; P &gt; .05), BATH (r = 0.142; P &gt; .05) and SAT (r = 0.227; P &gt; .05) had no significant positive correlation with biofilm formation.&#x0D; Conclusion: Thus, the metabolic traits potentials of these strains could be exploited for in situ bioremediation intervention in the coastal areas of Nigeria.

Organic contamination of beached plastic pellets in the South Atlantic: Risk assessments can benefit by considering spatial gradients

Microplastics are important vectors for the transport and accumulation of persistent organic contaminants in coastal and marine environments. We determined the concentration of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) associated with microplastic pellets collected along a 39-km stretch of Brazil's South Atlantic coastline to understand the spatial dynamics and potential risk posed by these contaminants. Total PAH concentrations ranged from 1,454 to 6,002 ng g−1 and regularly exceeded the threshold effect level (TEL) for sediments defined by the United States Environmental Protection Agency. Sampling stations, spaced evenly along the coastline (i.e., 3-km intervals) exhibited a general north-to-south decline in the concentrations of some PAHs, but this spatial gradient was complicated by small-scale differences in the concentrations and composition of associated contaminants. Similarly, analysis of individual isomer ratios revealed further complexity driven by differences in the contribution of petrogenic versus pyrolytic inputs which pose different levels of risk to marine organisms. PCB concentrations ranged from 0.8 to 104.6 ng g−1 and were dominated by low chlorinated congeners likely to have originated from major industrial areas to the north. Overall, this study highlights the challenge of directly linking microplastic pollution with the potential toxicological effects of organic contaminants in coastal waters. We recommend that monitoring programs should explicitly consider both the origin (i.e., pellet sources and dispersal pathways) and nature of organic contamination (i.e., concentration and composition) when assessing the risks for biota and human health.