Cadmium has had a number of historical applications in plastics but is now highly regulated. In this study, plastics containing pigmented or recycled Cd at concentrations up to 16,300 μg g⁻¹ were processed into microplastic-sized fragments and added to clean estuarine sediment. Plastic-sediment mixtures (mass ratio = 1:100) were subsequently exposed to fluids simulating the digestive conditions encountered in marine deposit-feeding invertebrates prepared from a protein and a bile acid surfactant in seawater and the mobilization of Cd measured as a function of time. Kinetic profiles over a six-hour period were complex, with some fitted using a diffusion model and others exhibiting evidence of Cd interactions between the plastic and sediment surface. The maximum concentration of Cd released from plastic-sediment mixtures was about 0.8 μg g⁻¹ and orders of magnitude greater than Cd mobilization from sediment alone. It is predicted that large communities of deposit-feeders could mobilize significant quantities of Cd from historical microplastics.

A molecularly imprinted polymer (MIP) anchored on the surface of CdTe quantum dots (QDs) was fabricated and used as a fluorescent probe for sulfadiazine (SDZ) detection in seawater. CdTe QDs was used as photoluminescent material, SDZ as the template, 3-aminopropyltriethoxysilane (APTES) as the functional monomer and tetraethyl orthosilicate (TEOS) as the cross-linking agent. Characterizations of MIP-QDs were analyzed by Fourier transform infrared (FT-IR), Transmission electron microscopy (TEM) and Scanning electron microscope (SEM). The conditions were optimized for the detection of MIP-QDs to SDZ. The mechanism of fluorescence quenching was studied by UV–Vis absorption spectroscopy and fluorescence spectroscopy. Under optimal conditions, the fluorescence intensity of MIP-QDs decreased linearly between 4‐ and 20 μM SDZ with a good correlation coefficient of 0.995. The limit of detection is 0.67 μM and the recovery is between 91.8 and 109.4% with RSD lower than 3.9%. These results indicated that MIP-QDs for SDZ detection in seawater was developed successfully.

To investigate bioavailability of dissolved organic nitrogen (DON) and its contribution to nitrogen demand for Ulva prolifera, a cruise was conducted during a bloom of U. prolifera in Qingdao coastal waters, China, dissolved inorganic nitrogen (DIN) and DON components were investigated. Uptakes of both DIN and DON by U. prolifera were synchronously measured onboard using stable isotope techniques. The contribution of DON to total dissolved N (TDN) was >50% and that of labile components (urea and to amino acids, AA) to DON exceeded 30%. Both DIN and DON were utilized by U. prolifera, which uptake NH4-N preferentially, then urea, NO3-N and AA in turn; whereas the ranking of turnover times from short to long was AA, NH4-N, urea and NO3-N. The high uptake rates and short turnover time of AA and urea indicated that DON may play an important role in the nutrition of U. prolifera.

Microplastics (MPs) contamination has been recognized as one of major threats to coastal marine environments. Although studies evidenced severe MPs contaminations to the Pacific Ocean, environmental implications of MPs concentrations, distributions, and characteristics have not been evaluated in sufficient detail. Here, we report on the distribution, abundance, and characteristics of MPs at the surface of the Northwestern Pacific Ocean, from which environmental implications are assessed. A manta trawl with a mesh size of ~330 μm and a rectangular net opening of 0.45 × 1 m was used to collect MPs samples on May 11–June 3, 2018. The MPs samples were sequentially isolated, digested, filtered, and characterized using an optical microscope, micro-Raman spectroscopy, and scanning electron microscopy. The results indicate the heterogeneity in abundance, shapes, color, and sizes of MPs. The study provides strong environmental implications such as sources, environmental degradation, residence time, transportation routes, and biological interactions.

Benzene, toluene, ethylbenzene, xylenes, naphthalene and n-hexane evaporating from a thin oil film was measured for 30 min in a small-scale test system at 2 and 13 °C and the impact of physicochemical properties on airborne benzene with time after bulk oil release was studied. Linear mixed-effects models for airborne benzene in three time periods; first 5, first 15 and last 15 min of sampling, indicated that benzene content in fresh oil, oil group (condensate/light crude oil) and pour point were significant determinants explaining 63–73% of the total variance in the outcome variables. Oils with a high pour point evaporated considerably slower than oils with a low pour point. The mean air concentration of total volatile organic compounds was significatly higher at 13 °C (735 ppm) compared to 2 °C (386 ppm) immediately after release of oil, but at both temperatures the concentration rapidly declined.

To identify the influence of tidal events on community functioning of periphytic ciliates for monitoring program and community research using biological trait analysis, a 3-month baseline survey was conducted in Korean coastal waters using the polyurethane foam enveloped slide system (PFES) and conventional slide system (CS). Although the periphytic ciliate communities had similar biological trait categories, they represented considerable differences in community functioning and functional diversity measures within the PFES and CS systems. Multivariate analyses revealed different ways of the temporal shift in community functioning of the ciliates in both systems. The dispersion analysis demonstrated that the CS system was sensitive to the strong disturbance of tidal current and circulation compared to the PFES system. These findings suggest that the strong tidal event may significantly influence the output of analysis on community functioning of periphytic ciliates for bioassessment in marine ecosystems.

Sediment samples were collected from Caofeidian Long Island, China to investigate the contamination level and distribution pattern of 16 polycyclic aromatic hydrocarbons (PAHs). Source identification and risk assessment were also performed on these PAHs. The distribution patterns and source identification results indicated that the PAHs in the survey area originated from coal, biomass, and petroleum combustion as well as the combination of these three processes. Although the concentration of fluorene in the sediment exceeded the ERL level in some sampling sites, the effect range low–effect range median ratio implied a relatively low level of toxicity in these sediments. Meanwhile, the mean effects range–median quotient indicated that the 16 PAHs in sediments from Caofeidian Long Island pose a low ecological risk.

Concentrations, spatial distribution and sources of aliphatic hydrocarbons (AH) and polycyclic aromatic hydrocarbons (PAH) were determined in surface seawater of the Gulf of Trieste, northern Adriatic. This area is one of the most industrialized and urbanized areas in the northern Adriatic with intense maritime traffic. The surface seawater samples were collected at 31 sites and total hydrocarbon concentrations were determined. In general, concentrations (0.1 to 43.2 μg l⁻¹, mean 4.8 μg l⁻¹, Chrysene equivalents) were higher in summer. Concentrations of total aliphatic hydrocarbons were from 17.2 to 2326.5 μg l⁻¹ (mean 543.3 μg l⁻¹). The major component was the unresolved complex mixture (UCM), comprising from 78% to 97% of the total aliphatic hydrocarbons. Total PAH concentrations varied from 89 ng l⁻¹ to 294 ng l⁻¹ (mean 179 ng l⁻¹). The most contaminated sites were the marina of San Giusto and the municipal harbor of Piran.Different evaluation indeces were applied to determine the origin of hydrocarbons. The prevailing origin of aliphatic hydrocarbons is petrogenic, with the significant contribution of the biogenic at some sites. The results presented indicate the fresh inputs of hydrocarbons, which are subject to intense degradation processes. The PAH group profile showed the predominance of 2–3 ring PAHs. PAHs were of mixed origin with more pronounced petrogenic origin, presumably due to oil spills from ships and boats. The presence of a relatively high content of perylene in seawater is an indication of its terrestrial input.According to the presented results and compared to results from different areas worldwide, the seawater in the Gulf of Trieste can still be considered slightly to moderately polluted with PAHs.

We study the evolution of large systems of sticky patches of pollution that float on the sea surface and are moved around by realistic wind and simulated surface currents. The study area is the Gulf of Finland in the eastern Baltic Sea that hosts extremely heavy cargo and tanker traffic. It is assumed that patches merge at collision. Collisions are enhanced by wind impact that depends on the patch size. We implement a space partitioning algorithm for fast simulations of large systems of >8000 patches and perform a series of simulations with different initial size and location of the patches. The resulting empirical distribution of the number of patches of different size is governed universally by a stretched-exponential power law f(x) = A exp (−xb). This indicates that the evolution of large systems of pollution patches on the sea surface exhibits classic self-organization and scale invariance properties. This may be the key effect explaining how the patchiness of waste in marine environment is formed under the impact of different drivers.

In the open ocean, floating surface debris such as plastics concentrate in five main accumulation zones centered around 30° latitude, far from highly turbulent areas. Using Lagrangian advection of numerical particles by surface currents from ocean model reanalysis, previous studies have shown long-distance connection from the accumulation zones of the South Indian to the South Pacific oceans. An important physical process affecting surface particles but missing in such analyses is wave-induced Stokes drift. Taking into account surface Stokes drift from a wave model reanalysis radically changes the fate of South Indian particles. The convergence region moves from the east to the west of the basin, so particles leak to the South Atlantic rather than the South Pacific. Stokes drift changes the South Indian sensitive balance between Ekman convergence and turbulent diffusion processes, inducing either westward entrainment in the north of the accumulation zone, or eastward entrainment in the south.