An important aspect of oil spill science is understanding how the compounds within spilled oil, especially toxic components, change with weathering. In this study we follow the evolution of petroleum hydrocarbons, including n-alkanes, polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs, on a Louisiana beach and salt marsh for three years following the Deepwater Horizon spill. Relative to source oil, we report overall depletion of low molecular weight n-alkanes and PAHs in all locations with time. The magnitude of depletion, however, depends on the sampling location, whereby sites with highest wave energy have highest compound depletion. Oiled sediment from an enclosed bay shows high enrichment of high molecular weight PAHs relative to 17α(H),21β(H)-hopane, suggesting the contribution from sources other than the Deepwater Horizon spill, such as fossil fuel burning. This insight into hydrocarbon persistence as a function of hydrography and hydrocarbon source can inform policy and response for future spills.

We examined the degree of DNA damage caused by fractions of crude oil in accordance with the boiling points, polarity and log Kow. Relatively high DNA damage was observed in the aromatic fraction (290–330°C) and resin and polar fraction (350–400°C). The resin and polar fraction showed relatively high genotoxicity compared with the aliphatic and aromatic fraction at the 1–4 log Kow range. At the 6–7 log Kow range, the aromatic fraction showed relatively high DNA damage compared with the aliphatic and resin and polar fraction. In particular, every detailed fraction in accordance with the log Kow values (aliphatic and aromatic (310–320°C) and resins and polar fractions (370–380°C)) showed one or less than one DNA damage. However, the fractions before separation in accordance with log Kow values (aliphatic and aromatic (310–320°C) and resin and polar (370–380°C) fractions) showed high DNA damage. Thus, we confirm the synergistic action between the detailed compounds.

Buccinanops globulosus is a TBT sensitive marine gastropod, classified as a good indicator of imposex incidence and used as a model to study adverse contamination effects. Population and maritime industries has incremented pollution in Nuevo gulf harbor since 1970s, promoting morphological changes in B. globulosus shell shape. We study the shell shape of the species comparing present day's specimens from the harbor zone with those collected in the same zone before the increasing of maritime activity and pre-Hispanic archaeological Middens. We demonstrated that harbor pollution produces globular shell shape in B. globulosus, an effect that probably allows gastropods to isolate themselves from the external adverse environment. On the contrary, shells from pre-Hispanic periods, unpolluted sites and those collected before the expansion of maritime activities, presented an elongated shell shape. Our study confirms that shell shape variation in marine gastropods can be used as a biomarker of harbor pollution.

This study aimed to investigate heavy metals content of mercury (Hg), lead (Pb), cadmium (Cd) and arsenic (As) in surface sediments of Chabahar Bay. Sediment samples were taken from 13 stations and then analyzed. The concentration of Hg, Pb, Cd and As ranged between 0.06 and 0.14ppm, 8 and 23ppm, 0.05 and 0.9ppm and 5 and 22ppm, respectively. Arsenic content was more than ERL at some stations. Statistical analyses indicated critical importance of organic matter and mud in metal dispersion. Also, positive correlation of Al with Pb, Hg and Cd probably implies their terrestrial origination. Average enrichment factor of Hg, Pb, Cd and As were 2.67±0.95, 0.77±0.28, 6.56±9.9, and 7.53±3.44, respectively. Most stations were classified as moderately polluted and non-polluted sites.

The organic enrichment of surficial sediments has a known effect on benthic faunal communities due largely to oxygen depletion and sulfide toxicity. Total dissolved sulfide (free S−2=H2S+HS−+S2−) concentrations in sediments are widely measured as a practical indicator of community effects. However, the standard ion selective electrode (ISE) method for free S−2 analysis can provide biased results owing to the inclusion of non-toxic mineral sulfides and the oxidation and volatilization of free S−2. A rapid field protocol was developed that alleviates these problems while also providing data on dissolved oxygen concentrations. Sediments collected near salmon aquaculture pens over cohesive and permeable substrates were analysed using the standard and new protocols. The results confirm previous conclusions of artifacts with the standard ISE method, while the dual indicator approach more accurately describes the stages, spatial extent and magnitude of sediment geochemical alterations affecting benthic communities.

Dissolved organic nitrogen (DON) is the major nitrogen form in the Bohai Sea. Land-based DON is released into the nitrogen pool and degraded by planktonic microbiota in coastal ocean. In this study, we evaluated the degradation of land-based DON, particularly its dynamics and bioavailability, in coastal water by linking experiment and modeling. Results showed that the degradation rate constant of DON from sewage treatment plant was significantly faster than those of other land-based sources (P<0.05). DON was classified into three categories based on dynamics and bioavailability. The supply of dissolved inorganic nitrogen (DIN) pool from the DON pool of Liao River, Hai River, and Yellow River was explored using a 3D hydrodynamic multi-DON biogeochemical model in the Bohai Sea. In the model, large amounts of DIN were supplied from DON of Liao River than the other rivers because of prolonged flushing time in Liaodong Bay.

Six marine biota species were collected from the Xuande Atoll, South China Sea to investigate the bioaccumulation of dichlorodiphenyltrichloroethane (DDT), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE) and dechlorane plus (DP). Pike conger (Muraenesox talabonoides) had the highest concentrations of halogenated organic pollutants (HOPs) among the six marine biota species. DDTs were the predominant HOPs, followed by PCBs and PBDEs, with minor contributions of DBDPE and DP. Twenty-one percent of samples had ratios of (DDE+DDD)/ΣDDTs lower than 0.5, implying the presence of fresh DDT inputs in the environment of the Xuande Atoll. The biomagnification factor values for DDTs, PCBs, PBDEs and DP were higher than 1, suggesting biomagnification of these contaminants in the marine food chains. Consumption of seafood from the Xuande Atoll might not subject local residents in the coastal areas of South China to health risks as far as HOPs are concerned.

Biological invasions are a major threat to the world's biota and are considered a major cause of biodiversity loss. Therefore, world marine policy has recognized the need for more marine protected areas (MPAs) as a major tool for biodiversity conservation. The present work experimentally evaluated how protected communities from an offshore island can face the settlement and/or expansion of nonindigenous species (NIS). First, NIS colonization success in marine protected and marina communities was compared by deploying PVC settling plates at the Garajau MPA and Funchal marina (SW Madeira Island). Then, the settling plates from the MPA were transferred to Funchal marina to test their resistance to NIS invasion under high levels of NIS pressure. Results indicated that the structure and composition of fouling communities from the MPA differed from those collected in the marina. Interestingly, communities from the protected area showed lower NIS colonization success, suggesting some degree of biotic resistance against NIS invasion.

The probability of major oil accidents in Arctic seas is increasing alongside with increasing maritime traffic. Hence, there is a growing need to understand the risks posed by oil spills to these unique and sensitive areas. So far these risks have mainly been acknowledged in terms of qualitative descriptions. We introduce a probabilistic framework, based on a general food web approach, to analyze ecological impacts of oil spills. We argue that the food web approach based on key functional groups is more appropriate for providing holistic view of the involved risks than assessments based on single species. We discuss the issues characteristic to the Arctic that need a special attention in risk assessment, and provide examples how to proceed towards quantitative risk estimates. The conceptual model presented in the paper helps to identify the most important risk factors and can be used as a template for more detailed risk assessments.

Toxic air pollution on city streets is a very important issue, as pollutants are associated with adverse health effects, including respiratory and cardiovascular diseases. This study compared commuters' exposures to inhalable suspended particulate matter (PM) for different transportation modes in Xi'an City, China. Four commuting modes—private car, subway, bus and walking—were selected for the study. Commuter exposure concentrations to PM (PM10, PM2.5, PM1.0) were investigated in the following microenvironments: private cars under four ventilation modes, subway trains and station platforms, buses under two different ventilation modes, and pedestrians. Pearson correlation analysis was used to analyze the relationships between commuter PM10, PM2.5 and PM1.0 exposure concentrations under the different commuting modes. A mixed-effect linear model was used to identify the effects of different commuting modes on PM mass and number concentrations in these different traffic microenvironments. The results indicated that the concentration of particulate matter (PM) is significantly influenced by transportation mode as well as by vehicle ventilation systems. Among the four commuting modes, commuters were exposed to the lowest concentrations of PM10 (11.83 ± 7.60 μg m−3), PM2.5 (10.09 ± 6.63 μg m−3) and PM1.0 (9.52 ± 6.17 μg m−3) in a private car with air conditioning recirculation. In contrast, passengers waiting for a train on a subway station platform were exposed to the highest PM concentrations (244.99 ± 43.19 μg m−3). Size fractions of PM differed greatly across PM exposures with the ratio of fine particles to coarser particles (PM2.5/PM10) varying from 45 to 96%.