Low levels of PAHs and organotin compounds in surface sediment samples from a broad marine area of 25 de Mayo (King George) Island, South Shetland Islands

Pseudomonas and Pseudarthrobacter are the key players in synergistic phenanthrene biodegradation at low temperatures

Hydrocarbon contamination, including contamination with polycyclic aromatic hydrocarbons (PAHs), is a major concern in Antarctica due to the toxicity, recalcitrance and persistence of these compounds. Under the Antarctic Treaty, nonindigenous species are not permitted for use in bioremediation at polluted sites in the Antarctic region. In this study, three bacterial consortia (C13, C15, and C23) were isolated from Antarctic soils for phenanthrene degradation. All isolated bacterial consortia demonstrated phenanthrene degradation percentages ranging from 45 to 85% for 50 mg/L phenanthrene at 15 ℃ within 5 days. Furthermore, consortium C13 exhibited efficient phenanthrene degradation potential across a wide range of environmental conditions, including different temperature (4-30 ℃) and water availability (without polyethylene glycol (PEG) 6000 or 30% PEG 6000 (w/v)) conditions. Sequencing analysis of 16S rRNA genes revealed that Pseudomonas and Pseudarthrobacter were the dominant genera in the phenanthrene-degrading consortia. Moreover, six cultivable strains were isolated from these consortia, comprising four strains of Pseudomonas, one strain of Pseudarthrobacter, and one strain of Paeniglutamicibacter. These isolated strains exhibited the ability to degrade 50 mg/L phenanthrene, with degradation percentages ranging from 4 to 22% at 15 ℃ within 15 days. Additionally, the constructed consortia containing Pseudomonas spp. and Pseudarthrobacter sp. exhibited more effective phenanthrene degradation (43-52%) than did the individual strains. These results provide evidence that Pseudomonas and Pseudarthrobacter can be potential candidates for synergistic phenanthrene degradation at low temperatures. Overall, our study offers valuable information for the bioremediation of PAH contamination in Antarctic environments.

Four Years of Active Sampling and Measurement of Atmospheric Polycyclic Aromatic Hydrocarbons and Oxygenated Polycyclic Aromatic Hydrocarbons in Dronning Maud Land, East Antarctica

Antarctica, protected by its strong polar vortex and sheer distance from anthropogenic activity, was always thought of as pristine. However, as more data on the occurrence of persistent organic pollutants on Antarctica emerge, the question arises of how fast the long-range atmospheric transport takes place. Therefore, polycyclic aromatic hydrocarbons (PAHs) and oxygenated (oxy-)PAHs were sampled from the atmosphere and measured during 4 austral summers from 2017 to 2021 at the Princess Elisabeth station in East Antarctica. The location is suited for this research as it is isolated from other stations and activities, and the local pollution of the station itself is limited. A high-volume sampler was used to collect the gas and particle phase (PM10) separately. Fifteen PAHs and 12 oxy-PAHs were quantified, and concentrations ranging between 6.34 and 131 pg m3 (Σ15PAHs-excluding naphthalene) and between 18.8 and 114 pg m3 (Σ13oxy-PAHs) were found. Phenanthrene, pyrene, and fluoranthene were the most abundant PAHs. The gas-particle partitioning coefficient log(Kp) was determined for 6 compounds and was found to lie between 0.5 and -2.5. Positive matrix factorization modeling was applied to the data set to determine the contribution of different sources to the observed concentrations. A 6-factor model proved a good fit to the data set and showed strong variations in the contribution of different air masses. During the sampling campaign, a number of volcanic eruptions occurred in the southern hemisphere from which the emission plume was detected. The FLEXPART dispersion model was used to confirm that the recorded signal is indeed influenced by volcanic eruptions. The data was used to derive a transport time of between 11 and 33 days from release to arrival at the measurement site on Antarctica.

Determination of organotin compounds in marine sediments from Arctic Svalbard and West Antarctic Fildes Peninsula

This study investigated the contamination levels of five typical organotin compounds in Arctic and Antarctic marine sediments. Organotin total concentrations ranged from not detected (ND) to 37.9 ng Sn/g dw and from ND to 34.0 ng Sn/g dw in surface sediments of Svalbard and Fildes Peninsula, respectively. Dibutyltin accounted for 11.3 %-100 % of butyltins in Arctic sediments, whilst diphenyltin was the predominant phenyltin species in both Arctic and Antarctic. However, the concentrations of tributyltin and triphenyltin were lower than low-substituted organotins in the study areas, indicating the effectiveness of international ban on the use of triorganotin-based antifouling paints. No significant difference in organotin contamination was found between Arctic and Antarctic, although the time suffered from human interference was shorter in the Antarctic. Overall, these data can provide a diagnosis of recent organotin inputs in polar regions and serve as a baseline for future study assessing their local applications.

Priority Organic Pollutants and Endocrine-Disrupting Compounds in Arctic Marine Sediments (Svalbard Islands, Norway)

The present study investigated the occurrence and distribution of polycyclic aromatic hydrocarbons (PAHs) and phenolic endocrine-disrupting compounds (PEDCs), including bisphenol A (BPA), 4-nonylphenol (4-NP), and its monoethoxylate (NP1EO) and diethoxylate precursors in marine sediments in an Arctic fjord (Svalbard, Norway). The contribution of different local sources of contamination was also evaluated, together with a risk assessment for the marine environment. Samples were collected during two consecutive summer seasons (2018 and 2019), and target contaminants were analyzed with gas chromatography-mass spectrometry (MS) and high-performance liquid chromatography-MS/MS. The results showed no statistical differences between total PAH concentrations measured in 2018 (mean value 53.7 ± 54.3 ng/g) and 2019 (mean value 58.1 ± 63.6 ng/g). Low-ring (three or four rings) PAHs were the most abundant congeners, and single PAH ratios indicated a predominance of petrogenic sources (i.e., coal and liquid fossil fuel combustion). Nonylphenols and BPA showed a significant decrease in 2019 compared to 2018; 4-NP and NP1EO prevailed in both years, particularly in sediments close to the Ny-Ålesund research village. Overall, the results indicate that local anthropic activities are the major source of contamination in the Kongsfjorden ecosystem, but also melting waters from glaciers in the summer season can play an important role as a secondary source of pollutants previously trapped in ice. Comparison between our data and empirical and mechanistic indices derived from sediment quality guidelines suggests that the occurrence of PAHs and PEDCs in sediments does not currently pose a risk for this Arctic ecosystem, but further investigation is needed on the spread of hazardous contaminants and their effects on these fragile environments. Environ Toxicol Chem 2023;42:953-965. SETAC.

Tributyltin exposure disrupted the locomotor activity rhythms in adult zebrafish (Danio rerio) and the mechanism involved

The fish circadian rhythm system might be an emerging target of tributyltin (TBT), however, the mechanism by which TBT interferes with the circadian rhythm is poorly understood. Therefore, in the present study, zebrafish were used to assess the effects of TBT at environmental concentrations (1 and 10 ng/L) on locomotor activity rhythm. Furthermore, we focused on the visual system to explore the potential mechanism involved. After 90 d of exposure, TBT disturbed the locomotor activity rhythms in zebrafish, which manifested as: (1) low activities and lethargy during the arousing period; (2) inability to fall asleep quickly and peacefully during the period of latency to sleep; and (3) no regular "waves" of locomotor activities during the active period. After TBT exposure, the histological structure of the eyes significantly changed, the boundary between layers became blurred, and the melanin concentrations significantly decreased. Using KEGG and GSEA pathway analyses, the differentially expressed genes in the eyes screened by transcriptomics were significantly enriched in the tyrosine metabolism pathway and retinol metabolism pathway. Furthermore, a decrease in melanin and disruption of retinoic acid were found after TBT exposure, which would affect the reception of phototransduction, and then interfere with the circadian rhythm in fish. The disruption of the circadian rhythm of fish by aquatic pollutants would decrease their ecological adaptability, which should be considered in future research.

Source risk, ecological risk, and bioeffect assessment for polycyclic aromatic hydrocarbons (PAHs) in Laizhou Bay and Jiaozhou Bay of Shandong Peninsula, China

In order to incorporate the contribution of pollution sources to ecological risks into environmental monitoring, positive matrix factorization-risk quotient (PMF-RQ) was used to quantify the contribution of different PAH sources to ecological risks, which indicated that the unburned petroleum, vehicular emissions, and diesel combustion were the main sources of PAHs in Laizhou Bay and Jiaozhou Bay, and they were caused by petrochemical industry, maritime shipping, and urban traffic exhaust as the major sources of PAHs for ecological risk. Meanwhile, integrated biomarker response (IBR) and multi-biomarker pollution index (MPI) suggested that September was the most polluted month for PAHs in Laizhou Bay and Jiaozhou Bay and the pollution in Laizhou Bay was significantly higher than that in Jiaozhou Bay. This research was dedicated to explore the monitoring pattern for PAH pollution from the source to bioeffects, and it may have contributed a scientific support to monitoring and governance of marine PAH pollution.