With increasing concern over the aquatic environment in marine culture, the integrated multi-trophic aquaculture (IMTA) has received extensive attention in recent years. A three-dimensional numerical ocean model is developed to explore the negative impacts of aquaculture wastes and assess the bio-mitigation effect of IMTA systems on marine environments. Numerical results showed that the concentration of surface phytoplankton could be controlled by planting seaweed (a maximum reduction of 30%), and the percentage change in the improvement of bottom dissolved oxygen concentration increased to 35% at maximum due to the ingestion of organic wastes by sea cucumbers. Numerical simulations indicate that seaweeds need to be harvested in a timely manner for maximal absorption of nutrients, and the initial stocking density of sea cucumbers >3.9 individuals m−2 is preferred to further eliminate the organic wastes sinking down to the sea bottom.

Pre-spill background concentrations of TPH and PAH in water samples from the Gulf of Mexico are compared with samples (over 20,000) collected during and after the Deepwater Horizon incident (13,000 stations). Samples were collected by multiple response agencies, trustees and BP and reported in the Gulf Science Data. The samples were collected from a few m to over 800km in all directions from the wellhead. During the incident, samples with the highest concentrations of hydrocarbons were collected proximal to the wellhead or in samples collected from surface slicks and dispersant use. Of the 13,172 water sample TPH concentrations reported, 84% were below 1μg/L (background). Of the 16,557 water sample PAH concentrations reported, 79% were below 0.056μg/L (the median field blank, background). The percentage of samples below background increased rapidly after the well was capped. The spatial and temporal distributions of these hydrocarbon data are presented.

Based on geochemical and magnetic approaches, the distribution, sources, and health risk of trace metals in surface sediments from a seashore tourist city were investigated. A significant correlation was found between magnetic susceptibility (χ) and trace metals, which suggested that levels of trace metals in the sediments can be effectively depicted by the magnetic approach. The spatial distribution of χ and trace metals matched well with the city layout with relatively higher values being found in the port and busy tourist areas. This result, together with enrichment factors (EFs) and Tomlinson pollution load index (PLI) of metals, suggested that the influence of human activities on the coastal environment was noticeable. Principal component analysis (PCA) indicated that trace metals in the sediments were derived from both anthropogenic and natural sources. Noncarcinogenic risk assessment showed that there was no potential health risk of exposure to metals by means of ingestion or inhalation.

Concentrations of 16 heavy metals and Pb isotopic ratios in the intertidal surface sediments of Quanzhou Bay were determined to study the pollution level of heavy metals and the sources of Pb. The results showed that most concentrations of Cd, Sn, Mn, Cu, Zn, Cr, Pb, Hg, Ni, Co, Cs, Fe and V were higher than the background values, while most concentrations of Ti, Sb and Sr were lower than the background values. The mean concentrations of Cu, Zn, Pb, Cr and Cd exceeded the first-grade criteria of Chinese marine sediment quality. The geo-accumulation indexes revealed that the sediments had been polluted by some heavy metals. The results of Pb isotopic tracing indicated that the total Pb in the sediments were mainly from parent material, industrial emission and vehicle exhaust with the mean contributions of 38.2%, 51.3% and 10.5%, respectively, calculated by a three-end-member model of Pb isotopic ratios.

Industrial pressures suffered by estuarine zones leave a pollution record in their sediment. Thus, high concentrations of many heavy metals and some organic compounds are often found in estuarine sediment. This work aims to contribute to the enhancement of water quality management strategies in these zones by studying in detail the diffusive processes that take place between the water and sediment using a two-pronged approach: experimental practice and numerical simulation. To provide an example of the practical application of the methodologies proposed in this paper, the Suances Estuary (northern Spain) was selected as the study zone. This estuary exhibits significant historical pollution and its sediment acts as a continuous internal source of zinc, mainly due to diffusive processes derived from the concentration gradient between the interstitial water at the solid particles of the sediment and the bottom of the water column. The experimentally obtained results, based on 6 case studies, demonstrated the buffering capacity of the system and allowed the determination of the required time for the mass transfer processes to reach an equilibrium state. Furthermore, the diffusion rate of zinc was approximately modeled taking into consideration the high concentration variability observed in sediment along the entire estuary. The convergence between the modeled and the experimental results indicated the required contact time to reach an equilibrium state in a real field situation.

A survey of juvenile Asian horseshoe crabs in 2002 on the mudflats along Hong Kong's north-western shoreline abutting Deep Bay identified two species, Tachypleus tridentatus and Carcinoscorpius rotundicauda, and assessed their population characteristics. Since the 2002 survey, there have been significant habitat changes to this natal site for the two species. By employing the same, but expanded, sampling protocol, a further survey was, therefore, conducted twelve years later in 2014. A general population decline was recorded for T. tridentatus whereas for C. rotundicauda there was an increase and its distribution had become more widespread. The distribution patterns of the two species were also shown to have changed. The potential factors that might be responsible for recorded changes in the species' population characteristics between 2002 and 2014 are related to anthropogenic perturbations, including environmental habitat alterations notably the building of a bridge linking Hong Kong to Shenzhen in China.

Marine debris (MD) pollution is a problem of global concern because of its impact on marine ecosystems. The current extent of this problem and its implications concerning reef conservation are unknown in Ecuador. The composition and distribution of submerged MD was assessed on two reefs using underwater surveys of geomorphological areas: crest, slope and bottom. MD items were classified according to source and use. Plastic-derived debris represents >90% of total MD found on the reefs, principally composed by plastic containers and nets. 63% of the MD was associated to fishing activities. The composition showed differences between sites and geomorphological areas, monofilament nets were found on the crests, multifilament lines on the slopes and plastic containers on the bottom. MD disposal might be a result of the influx of visitors and fishing activities. Distribution is related to bottom type, level of boating/fishing activity and benthic features.

Seabirds are vulnerable to oil pollution, particularly in cold-water regions. We investigated the response of small spills (<7.95m3) at offshore production platforms in Newfoundland, a region recognized for seabird diversity and abundance. In three environmental assessments for oil production operations Environment Canada requested monitoring and mitigation of small spills potentially impacting seabird populations; suggestions supported by two independent reviews. An industry spill response plan states that operators would collect systematic observations on spills and deploy countermeasures where possible. Operators' spill reports were obtained under an Access to Information request. There were 220 daytime spills with sheens (out of 381 spills; 1997–2010). Of these, six reported time to oil dispersion and eleven the presence or absence of seabirds. Industry self-reporting has not permitted an evaluation of the impact of chronic oil spills on seabirds. We recommend that independent observers be placed on platforms to systematically collect data on spills and seabirds.

This paper discusses the combined use of tools from dynamical systems theory and remote sensing techniques and shows how they are effective instruments which may greatly contribute to the decision making protocols of the emergency services for the real-time management of oil spills. This work presents the successful interplay of these techniques for a recent situation, the sinking of the Oleg Naydenov fishing ship that took place in Spain, close to the Canary Islands, in April 2015.

The concentrations of ozone (O3) and nitrogen oxides (NOx) were measured at two mountainous sites in Buk-Han (BH) and Gwan-Ak (GA) and at a reference site in Gwang-Jin (GJ), all in Seoul, South Korea, over a four-year period (2010–2013). The mean concentration (ppb) of NOx was comparable at the mountainous sites (22.9 ± 20.7 (BH) and 20.9 ± 16.9 (GA)) but about half the concentration at the reference site in GJ (47.8 ± 36.4). In contrast, the mean value (ppb) for O3 at the three sites exhibited a reversed pattern such as 40.2 ± 19.7 at GA, 28.6 ± 15.4 at BH, and 21.8 ± 18.3 at GJ. The concentration of NOx was higher in winter/fall relative to summer/spring at all three sites. Like the clear distinctions observed from the spatial distribution patterns, the seasonal trends conrasted sharply between NOx and O3. Results of a correlation analysis suggested that the distribution of O3 was significantly affected by meteorological parameters (e.g., TEMP, UV, and solar radiation). According to a back trajectory analysis, the highest O3 levels at both mountainous sites were caused by air masses passing over marine areas, while the effects of ozone precursors on ozone concentration were attributed to air masses originating from China and/or the mainland (S. Korea).