Deep-water oil spills represent a major, localized threat to marine ecosystems. Multi-purpose computer models have been developed to predict the fate of spilled oil. These models include databases of pseudo-components from distillation cut analysis for hundreds of oils, and have been used for guiding response action, damage assessment, and contingency planning for marine oil spills. However, these models are unable to simulate the details of deep-water, high-pressure chemistry. We present a new procedure to calculate the chemical properties necessary for such simulations that we validate with 614 oils from the ADIOS oil library. The calculated properties agree within 20.4% with average values obtained from data for measured compounds, for 90% of the chemical properties. This enables equation-of-state calculations of dead oil density, viscosity, and interfacial tension. This procedure enables development of comprehensive oil spill models to predict the behavior of petroleum fluids in the deep sea.

The effects of simulated electromagnetic fields (EMF), emitted from sub-sea power cables, on the commercially important decapod, edible crab (Cancer pagurus), were assessed. Stress related parameters were measured (l-Lactate, d-Glucose, Haemocyanin and respiration rate) along with behavioural and response parameters (antennular flicking, activity level, attraction/avoidance, shelter preference and time spent resting/roaming) during 24-h periods. Exposure to EMF had no effect on Haemocyanin concentrations, respiration rate, activity level or antennular flicking rate. EMF exposure significantly disrupted haemolymph l-Lactate and d-Glucose natural circadian rhythms. Crabs showed a clear attraction to EMF exposed shelter (69%) compared to control shelter (9%) and significantly reduced their time spent roaming by 21%. Consequently, EMF emitted from Marine Renewable Energy Devices (MREDs) will likely affect edible crabs both behaviourally and physiologically, suggesting that the impact of EMF on crustaceans must be considered when planning MREDs.

Thirty sediment samples from four different beaches along Bahia Solano and Nuquí (Department of Chocó) of eastern Colombia, with tourism and gold mining activities, were analysed to estimate the concentrations of fourteen different acid leachable metals. Metal distribution patterns showed elevated concentrations of Co, Cr, Cu, Pb and Zn compared with the upper continental crust values. Calculation of geochemical indices confirmed that the enrichment is due to periodic gold mining activities (severe to extremely severe enrichment of Cu, Zn, V, Co, Cr and Pb) along with natural (geological) contributions (minor and moderate enrichment of Ca, Mg, Fe, Ti, Mn and Li). Potential ecological risk index revealed that Pb posed the highest risk. Our results together with a global comparison suggest that the observed metal enrichments are mainly caused by mining and to a lesser extent by tourism in this region, thus instigating continuous monitoring of metal concentrations in this region.

Acid-volatile sulfides (AVS) formation and its role on trace metals bioavailability were studied in semi-arid mangroves. The semi-arid climatic conditions at the studied sites, marked by low rainfall and high evapotranspiration rates, clearly limited the AVS formation (AVS contents varied from 0.10 to 2.34μmolg−1) by favoring oxic conditions (Eh>+350mV). The AVS contents were strongly correlated with reactive iron and organic carbon (r=0.84; r=0.83 respectively), evidencing their dominant role for AVS formation under semi-arid conditions. On the other hand, the recorded ΣSEM/AVS values remained >1 evidencing a little control of AVS over the bioavailability of trace metals and, thus, its minor role as a sink for toxic metals.

Southwest Atlantic (SWA) estuaries have been historically impacted by industrial and agricultural activities that represent an important source of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). Intraspecific differences in OCPs and PCBs levels were evaluated in the benthic polychaete Laeonereis culveri from SWA estuaries (Samborombón; Mar Chiquita; Quequén Grande and Bahía Blanca) at different spatio-temporal scales. Regarding inter- and intra-estuarine spatial comparisons polychaetes showed significant differences in OCPs/PCBs levels (p < 0.05) being DDTs, endosulfan, penta- and hexa-CBs homologues the most representative compounds. Intra-estuarine comparisons also showed significant differences in terms of seasonality and body size (p < 0.05). OCPs/PCBs concentrations were negatively correlated with animal weight, but this covariable was not relevant on differences observed. OCPs/PCBs levels in polychaetes showed strong relationships with those of sediments, being suitable for estuarine biomonitoring studies. Seasonal and body-size differences found in OCPs and PCBs levels in tissues reveal the importance of these factors for intra-estuarine monitoring.

Hydrological regimes are key in shaping the structure of phytoplankton communities in estuaries. Because anthropogenic disturbances often alter the quantity and quality of riverine inputs, this research focused on investigating phytoplankton dynamics in the St. Lucia Estuary, since being reconnected to the Mfolozi River. Due to the closed mouth state of the estuary, the input from the river resulted in oligohaline (≥5) conditions and the characteristic reverse salinity gradient to persist throughout the study (i.e. one year). Model results indicated that phytoplankton communities were structured by rainfall, light transmittance and depth, while shifts between dominant groups were driven by salinity and flow season. The persistence of chlorophytes and euglenophytes as the co-dominant functional group indicates the freshening and nutrient-enriched nature of the river. This study provides the first detailed account documenting the response of the phytoplankton community to recent restoration efforts in the St Lucia Estuary, a Ramsar Site.

Particulate phosphorus was the dominant phosphorus species and accounted for 72 ± 5% of total phosphorus in coastal habitats, 63 ± 4% in estuaries, 58 ± 6% in lakes and 80 ± 7% in aquaculture farms whereas dissolved inorganic phosphorus (DIP) and dissolved organic phosphorus (DOP) were minor components. Correlation analyses (DIP vs Chl a; R2 = 0.407, df = 31, p < 0.001) suggested phosphorus limiting conditions in lakes, which was corroborated with the highest alkaline phosphatase activity (APA) that fluctuated from 0.38 to 41.14 nmol L−1 min−1. In contrast, APA was elevated in coastal habitats and estuaries only when DIP concentration decreased below 0.9 μM. Moreover size-fractionation experiment showed that the highest APA was detected in the 0.2–2 μm pico-size fraction. Our results suggested that the main APA in coastal habitats and estuaries was from phototrophic pico-eukaryotes and heterotrophic bacteria, and regulated largely by DIP availability.

This study's objectives were to evaluate the elements degree of contamination in the Tajan River and the status of contamination in this river for future ecotoxicology studies. Based on geo-accumulation index (Igₑₒ) and contamination factor (CF) indices, Cr, Mn, Fe, Ci, Ni and Zn showed low contamination levels at all stations, while Se showed a very high degree of contamination. Potential ecological risk factor (Eᵣⁱ) and risk index (RI) indices values showed low ecological risk for the river, and this was confirmed by the pollution load index (PLI) results as well as a comparison of the concentrations of these elements with the mean values of the earth's crust and sediments worldwide. Overall, the results showed that the river cannot be regarded as a contaminated river with respect to the elements studied (with the exception of selenium and arsenic) for ecotoxicology studies, but can be considered a reference river.

In this study, the activity concentrations of ²¹⁰Po and ²¹⁰Pb were determined in different types of bivalve molluscs sampled during the period of May 2014–June 2015 along the Andalusian littoral. Radioactivity concentrations of ²¹⁰Po were determined through alpha-particle spectrometry using ²⁰⁹Po as an internal tracer. Radioactivity concentrations of ²¹⁰Pb were determined through low-level gamma-ray spectrometry. The activity concentrations of ²¹⁰Po and ²¹⁰Pb varied between 40 ± 2 and 515 ± 9 Bq kg⁻¹ dry weight (d.w.), and ND (lower than limit of detection) and 73 ± 10 Bq kg⁻¹ d.w., respectively. The committed effective dose to humans was calculated to range from 39 to 477 μSv year⁻¹. Radioactivity and dose levels were compared with previous studies from other countries.

This study was designed to investigate the characteristics of bacterial communities in intertidal sediments along the Yangtze Estuary and their responses to environmental factors. The results showed that bacterial abundance was significantly correlated with salinity, SO42− and total organic carbon, while bacterial diversity was significantly correlated with SO42− and total nitrogen. At different taxonomic levels, both the dominant taxa and their abundances varied among the eight samples, with Proteobacteria being the most dominant phylum in general. Cluster analysis revealed that the bacterial community structure was influenced by river runoff and sewerage discharge. Moreover, SO42−, salinity and total phosphorus were the vital environmental factors that influenced the bacterial community structure. Quantitative PCR and sequencing of sulphate-reducing bacteria indicated that the sulphate reduction process occurs frequently in intertidal sediments. These findings are important to understand the microbial ecology and biogeochemical cycles in estuarine environments.