Ecological effects and quality status of sediments in the Bohai Bay (North China) were studied by incorporating the traditional chemical analysis and benthic community structure. In the present study, paired sediments from 20 stations were sampled for chemical analysis and benthic assemblages. The overall results demonstrated that sediment impairment mainly appeared in the southern part of the Bay. The results obtained from the principal component analysis regarding benthic data and potential explanatory factors indicated that As, Hg and petroleum hydrocarbons (PHs) were responsible for the distribution of macrofaunal assemblages. Canonical correspondence analysis further showed As was significantly correlated to the benthic alteration, which provided evidence of ecological relevance to chemical substances of concern. Overall, this study revealed the metal contamination in the Bohai Bay was not as severe as previously regarded. Yet, further investigation is still needed considering the complexity of sediment matrices.

Novel photocatalysts i.e., metallic nickel and zinc oxide nanoparticles embedded in the carbon-shell ((Ni–ZnO)@C) have been used for photocatalytic splitting of seawater to generate H2. The (Ni–ZnO)@C core–shell nanoparticles having the Zn/Ni ratios of 0–3 were prepared by carbonization of Ni2+- and Zn2+-β-cyclodextrin at 673K for 2h. To increase the collision frequency of water and photoactive sites within the carbon-shell, Ni and ZnO are partially etched from the (Ni–ZnO)@C core–shell to form yolk–shell nanoparticles with a H2SO4 solution (2N). By X-ray diffraction spectroscopy, mainly Ni and ZnO crystallites are observed in the core– and yolk–shell nanoparticles. The sizes of the Ni and ZnO in the (Ni–ZnO)@C nanoreactors are between 7 and 23nm in diameters determined by TEM and small angel scattering spectroscopy. Under a 5-h UV–Vis light irradiation, 5.01μmol/hgcat of H2 are yielded from photocatalytic splitting of seawater effected by (Ni–ZnO)@C nanoreactors.

The majority of plastic debris found in the marine environment has land based sources and rivers are considered an important medium for transfer of this debris. Here we report on the quantity and composition of floating plastic debris collected from surface waters of the Tamar Estuary. This represents the first study of riverine transport of floating plastic debris into European waters during different tidal regimes. Plastics were found in a variety of forms and sizes and microplastics (<5mm) comprised 82% of the debris. The most abundant types of plastic were Polyethylene (40%), Polystyrene (25%) and Polypropylene (19%). There was a significant difference in size frequency distribution between the spring and neap tides with more fragments of larger size observed during spring tides. While it is clear that debris has accumulated on shorelines within the estuary, during our study this river did not identify as a net source or sink.

The accumulation of metals in tissue compartments of bivalve biomonitors is expected to reflect the phases in which metals are most bioavailable. In concurrent field and laboratory experiments we measured Zn, Cd and Pb concentrations in the gills and digestive glands of mussels exposed to sediments from Lake Macquarie in NSW, Australia. Mussels in the laboratory were also exposed to the bioturbating gastropod Batillaria australis. Zn, Cd and Pb concentrations in gills and digestive glands of mussels from both experiments were accumulated in proportion with levels of metal contamination in the sediments. An interaction in the field between site and tissue type was found for Cd and Pb suggesting variation in the phases in which metals are most bioavailable. No effect of bioturbation on metal accumulation in the bivalve was detected and we conclude that it is unlikely to be a significant factor in metal uptake when these species interact.

The present study aimed to evaluate heavy metal concentrations of Arsenic (As), Copper (Cu), Nickel (Ni), Lead (Pb) and Zinc (Zn), their spatial distribution, enrichment factor index (EF), the pollution load index (PLI) and potential ecological risk (PER) in two different seasons of the year (winter and summer) in surface sediments along southeast coast of the Caspian Sea. The results indicated that there were significant differences between concentrations of As, Ni and Pb in two different seasons. Considering PER, sediments from southeast Caspian coast had low ecological risk. According to PLI, sediment from the southeast coast had no pollution. Risk assessment showed that As threshold concentrations to occasionally be exceeded in the study area.

Sediment samples from 13 sampling sites in Deception Bay, Australia were analysed for the presence of heavy metals. Enrichment factors, modified contamination indices and Nemerow pollution indices were calculated for each sampling site to determine sediment quality. The results indicate significant pollution of most sites by lead (average enrichment factor (EF) of 13), but there is also enrichment of arsenic (average EF 2.3), zinc (average EF 2.7) and other heavy metals. The modified degree of contamination indices (average 1.0) suggests that there is little contamination. By contrast, the Nemerow pollution index (average 5.8) suggests that Deception Bay is heavily contaminated. Cluster analysis was undertaken to identify groups of elements. Strong correlation between some elements and two distinct clusters of sampling sites based on sediment type was evident. These results have implications for pollution in complex marine environments where there is significant influx of sand and sediment into an estuarine environment.

Atmospheric mercury exits primarily as gaseous mercury and particulate mercury (PHg). Change in the species of atmospheric mercury will pose significant impact on the biogeochemical process of mercury. Here total gaseous mercury (TGM) and total particulate mercury (TPM) were measured from heating season in wintertime to springtime with frequent dust storm during February to May 2009 in the suburban of Hefei, central China, where atmospheric mercury measurements were completely absent. The average concentrations of TGM and TPM were 2.57±1.37ng/m3 and 0.32±0.10ng/m3, respectively. Variations in the TGM were affected by both emissions and meteorological parameters. In the heating period (February), due to coal combustion TGM concentrations were significantly higher than those in the spring (March, April and May). A clear different diurnal variation in TGM concentration was also observed both in late winter and in spring, accompanying with the advance of sunrise. The percentage of total particulate mercury (TPM) in total atmospheric Hg ranged from 5.8%–19.2%, with relatively high levels appeared in March and April. PHg was mainly derived from direct emissions by coal combustion in February and May, while it was dominated by transformation from gaseous Hg on particles in March and April due to dust storms, which may result in more deposition of mercury to ecosystem.

A large amount of oil pollution at sea is produced by the operational discharge of oily wastewater. The removal of polycyclic aromatic hydrocarbons (PAHs) from such sources using UV irradiation has become attractive, yet the photolysis mechanism in seawater has remained unclear. This study examines the photodegradation kinetics of naphthalene in natural seawater through a full factorial design of experiments (DOE). The effects of fluence rate, salinity, temperature and initial concentration are investigated. Results show that fluence rate, temperature and the interaction between temperature and initial concentration are the most influential factors. An increase in fluence rate can linearly promote the photodegradation process. Salinity increasingly impedes the removal of naphthalene because of the existence of free-radical scavengers and photon competitors. The results will help understand the photolysis mechanism of PAHs and develop more effective methods for treating oily seawater generated from offshore industries.

Derelict fishing gear is a source of mortality for target and non-target marine species. A program employing commercial watermen to remove marine debris provided a novel opportunity to collect extensive spatially-explicit information for four consecutive winters (2008–2012) on the type, distribution, and abundance of derelict fishing gear and bycatch in Virginia waters of Chesapeake Bay. The most abundant form of derelict gear recovered was blue crab pots with almost 32,000 recovered. Derelict pots were widely distributed, but with notable hotspot areas, capturing 40 species and over 31,000 marine organisms. The target species, blue crab, experienced the highest mortality from lost pots with an estimated 900,000 animals killed each year, a potential annual economic loss to the fishery of $300,000. Important fishery species were captured and killed in derelict pots including Atlantic croaker and black sea bass. While some causes of gear loss are unavoidable, others can be managed to minimize loss.

This study focuses on the coastal monitoring network established in the scope of WFD implementation. The objective of this network was to provide an ecological assessment of Valencian coastal waters. After three years, sufficient data had been collected to enable us to analyse and explore ways to increase the network’s efficiency.A methodology was developed to select the best subset of sampling stations to be surveyed. This method was approached from the perspective of an inter-observer variability problem. In order to compare the concordance between the k-observers and the reference observer, two measures were considered: euclidean distance, and interclass correlation coefficient.The obtained results confirm that the current network can be reduced by over 50% and still guarantee accurate results. This methodology (not limited by indicators, geographically, or by type of water body) could be applied to different environmental monitoring networks and could significantly decrease the efforts and costs required by the WFD.