Mangrove sediment harbors a unique microbiome and is a hospitable environment for a diverse group of bacteria capable of oil biodegradation. Our goal was to understand bacterial community dynamics from mangrove sediments contaminated with heavy-oil and to evaluate patterns potentially associated with oil biodegradation is such environments. We tested the previously proposed hypothesis of a two-phase pattern of petroleum biodegradation, under which key events in the degradation process take place in the first three weeks after contamination. Two sample sites with different oil pollution histories were compared through T-RFLP analyses and using a pragmatic approach based on the Microbial Resource Management Framework. Our data corroborated the already reported two-phase pattern of oil biodegradation, although the original proposed explanation related to the biophysical properties of the soil is questioned, opening the possibility to consider other plausible hypotheses of microbial interactions as the main drivers of this pattern.

In order to evaluate trace element bioavailability and potential transfer into marine food chains in human impacted areas of the Fildes Peninsula (King George Island, South Shetland Islands Archipelago), element levels (Cr, Ni, Cu, Zn, Cd, and Pb) were determined in water, sediments, phytoplankton, and in diatom Phaeodactylum tricornutum Bohlin (Bacillariophyceae) cells immobilised in alginate and exposed to water and sediments, from the Bellingshausen Dome (reference site) and Ardley Cove (human impacted area), during January 2014. High element concentrations in exposed P. tricornutum indicated element mobilisation from sediments into the water. Levels in exposed cells reflected the sediment element content pattern, comparable to those found in phytoplankton, supporting phytoplankton as an important path of trace element entry into marine food chains. This study clearly shows immobilised P. tricornutum as good proxy of phytoplankton concerning element accumulation efficiency, and an effective tool to monitor trace element contamination in polar coastal ecosystems.

An important component of microplastic research is development of reproducible methods for microplastic recovery and characterization. Presented is a review of the literature comparing microplastic separation and identification methodologies from seawater, sediment and marine organisms. The efficiency of methods was examined, including processing time, recovery rates, and potential destruction of microplastics. Visual examination and acid digestion were the most common separation methods for seawater samples and organisms, while density flotation was the primary method for sediment. Few studies reported recovery rates, or investigated the physical or chemical impact on plastics. This knowledge gap may lead to misidentification of plastic or unreliable pollution estimates. Further investigation of the impact chemical treatments have on plastic is warranted. Factors, i.e. biomass loading, recovery rates, and chemical compatibility, must be considered to allow for appropriate methodology. Standardizing this will contribute to efficient sample processing, and allow for direct comparison of microplastic contamination across environments.

This study investigates the influence of the most dominant factors (association patterns, gender, natal philopatry and anthropogenic pressure) on the home range size of the 44 most resident common bottlenose dolphins (Tursiops truncatus) inhabiting the waters of the Cres-Lošinj archipelago (north Adriatic Sea, Croatia), a recently declared NATURA 2000 SCI. Results show that variations in home range patterns (MCP, 95% KDE and 50% KDE home range size) among the individual resident dolphins are primarily related to differences in gender and reflect the way in which different genders respond to external stressors. In addition, results confirm the seasonal influence of nautical tourism on both female and male dolphins through changes in their home range sizes. The overall results improve current knowledge of the main anthropogenic threats that should be taken into consideration when developing conservation measures to be applied to this Cres and Lošinj SCI.

The temporal and spatial distributions of mercury in different fractions and its potential ecological risk were investigated in sediments from the Yangtze River estuary (YRE) by analyzing data collected from the study area. The results showed that mercury in the organic and residual fractions had dominant proportions, from 15.2% to 48.52% and from 45.96% to 81.59%, respectively. The fractions were more susceptible to seasonal changes than other fractions. Higher proportions of mercury in organic fraction were found in wet seasons; the opposite was true for mercury in residual fraction. With respect to the spatial distribution, the concentration mercury in exchangeable, carbonate and Fe-Mn oxide fractions showed a decreasing trend from the inner estuary to the outer estuary, but no obvious trends were found in the distributions of mercury in the organic and residual fractions. The risk assessment code (RAC) was used to evaluate the potential ecological risk in the study area based on the proportions of exchangeable and carbonate fractions. The average RAC values during the four periods were 6.00%, 2.20%, 2.83%, and 0.61%. Although these values show that the risk in the study area is generally low, the distribution of RAC values indicates that the inner estuary has a medium risk, with a value up to 10%.

Biodegradation is an important process for hydrocarbon weathering that influences its fate and transport, yet little is known about in situ biodegradation rates of specific hydrocarbon compounds in the deep ocean. Using data collected in the Gulf of Mexico below 700m during and after the Deepwater Horizon oil spill, we calculated first-order degradation rate constants for 49 hydrocarbons and inferred degradation rate constants for an additional 5 data-deficient hydrocarbons. Resulting calculated (not inferred) half-lives of the hydrocarbons ranged from 0.4 to 36.5days. The fastest degrading hydrocarbons were toluene (k=−1.716), methylcyclohexane (k=−1.538), benzene (k=−1.333), and C1-naphthalene (k=−1.305). The slowest degrading hydrocarbons were the large straight-chain alkanes, C-26 through C-33 (k=−0.0494 through k=−0.007). Ratios of C-18 to phytane supported the hypothesis that the primary means of degradation in the subsurface was microbial biodegradation. These degradation rate constants can be used to improve models describing the fate and transport of hydrocarbons in the event of an accidental deep ocean oil spill.

To remove benzo[a]pyrene (BaP) that has accumulated in the Jiaozhou Bay wetland sediment, two strains (JB1 and JB2) were selected from the BaP-contaminated the wetland sediment and immobilized in coal cinder and chitosan beads using entrapping and surface adsorption methods. Biodegradation of BaP in sediment was carried out in pots. The results showed that, supported by the coal cinder and chitosan beads, 71.9, 65.5, 58.9 and 66.1% of the BaP in the immobilized cells was degraded after 40d. These percentages were clearly higher than the 47.7% that degraded from free cells. Kinetic analysis indicated that the immobilized gel-beads might remove BaP by multiple control steps. Compared to the chitosan, coal cinder-entrapping beads exhibited a higher removal rate for BaP; however, the degradation rates from coal cinder- and chitosan-surface adsorption beads were almost the same. This result indicates that in addition to the BaP-degrading bacteria, carrier materials and immobilizing methods play an important role in determining the success of a biodegradation strategy.

An increasing number of studies highlight the risk of plastic pollution in the marine environment. However, systematic longitudinal data on the distribution and abundance of plastic debris remain sparse. Here we present the results of a two-year study of plastic pollution within the Tasman Sea, contrasted with a further year of data from the same region, in order to document how the density of debris varies across years in this area. Surface net tows were collected between Hobart, Tasmania and Sydney, Australia during the spring of 2013 and 2014 and compared with a subset of data from autumn 2012 from the same region. Substantial inter-annual variation in mean plastic abundance was observed over the three year period, ranging from to 248.04–3711.64pieceskm−2, confirming the need for multiple years of sampling to fully estimate the extent of, and trends in, plastic pollution.

The concentrations of 16 metals were assessed in snoek(Thyrsites atun; n=20) and yellowtail (Seriola lalandi; n=37) sampled from the West and South-East coasts of South Africa. Variability was observed at both small (Al, Cr, Hg, Pb, Mn and Cu) and large (As and Cu) spatial scales while inter-specific examination revealed diverse metal concentrations in snoek (Higher levels: Cr, Mn, Co, Hg and Pb) and yellowtail (higher levels: Fe and Cu). Zn, As and Hg were positively correlated with yellowtail size with no such correlations in snoek. Mean concentrations of As (0.61mg·kg−1; 0.98mg·kg−1), Cd (0.008mg·kg−1; 0.004mg·kg−1), Hg (0.27mg·kg−1; 0.16mg·kg−1) and Pb (0.009mg·kg−1; 0.005mg·kg−1) for snoek and yellowtail respectively were within regulatory guidelines. However, 10% (n=2) of snoek exceeded Hg maximum allowable limit, suggesting caution and further investigation. Overall, two meals (150g) per week of snoek or larger yellowtail (12–15kg) can be safe for human (adult) consumption.

Most of urban air quality studies focus on the megacities of North America, Europe and, recently, Asia. Meanwhile, the most polluted urban areas in the world are rapidly growing large, mid-size and small cities of Asia, Middle East, Africa and South America. This raises a question: why relatively smaller cities are more polluted than the megacities? This study presents the first comprehensive decade-long analysis of the effects of fuel and transport regulations on PM2.5 (particulate matter of aerodynamic diameter <2.5 μm) pollution in Quito, a medium-size city of South America. The effectiveness of a number of regulations is quantified through the elaboration of a high accuracy (98%) regression model. The model estimated that the PM2.5 concentrations were reduced by 67.6 μg/m3, combating the effect of city growth and intense motorization, reducing the annual PM2.5 concentrations to 17.4 μg/m3. This study is recommended as a guideline for thousands of other cities worldwide looking for optimal urban particulate pollution management.