Microplastic pollution in estuarine and coastal environments has recently been characterised in several countries but few researchers have addressed the influence of different forms of coastal zone use on the distribution of microplastic. Here, microplastic particles were sampled in Hangzhou Bay, which is heavily influenced by a range of human activities, and their abundance, size, and polymer type characterised. The abundance of microplastics was 0.14 ± 0.12 items/m³ in water, 84.3 ± 56.6 items/kg dry weight of sediment, and between 0.25 ± 0.14 and 1.4 ± 0.37 items/individual in biota. These results show that Hangzhou Bay has a low level of microplastic contamination compared to other coastal systems in China, although abundance was spatially variable within the bay; relatively higher microplastic abundances were found in the southern area of the bay, which has adjacent industrial and urban land-use zones, while lower abundances were observed in the central and northern bay areas where mariculture, fisheries, and mineral and energy industries are most common. The relatively low microplastic abundance observed in the biota samples is consistent with the generally low values for the seawater and sediment samples. Pellets were the most common of four particle-shape classes (fibres, fragments, films, and pellets) in surface seawater, while fibres were most abundant in sediment and biota. Smaller-sized microplastics (<1.0 mm) were dominant in all samples. Microplastics in the surface seawater were dominated by low-density polypropylene and polyethylene particles, while rayon was dominant in the sediment and biota samples. Our results demonstrate that regional variability in anthropogenic activity and land-use are important controls on the spatial pattern of microplastic pollution in Hangzhou Bay.

China is the largest plastic consumer in the world. Despite its plastic waste import ban in 2017, this populous economy inevitably generates a large amount of waste, including plastic waste, a considerable part of which has become marine litter. Data from the 2018 National Coastal Cleanup and Monitoring Project, the largest beach litter monitoring activities using the citizen science approach in China, have been retrieved and analyzed to understand spatial patterns, composition, and original usage of marine litter. Within this project, 24 beaches were surveyed every two months. As a result, the mean density was 3.85 ± 5.39 items m⁻², much higher than that reported by previous studies in China. There were great differences in the spatial distribution of litter. The highest densities appeared in the runoff-affected area of the Yangtze River, which was another difference from previous studies. Low-density, easy-to-transport foamed plastics were the major contributor to marine litter in these areas. Along China’s coast, approximately 90% of litter was from land-based sources, and over half of that originated from domestic sources. Including foamed plastic products, plastic litter with low recycling value dominated. Both natural and human factors influencing the spatiotemporal distribution and composition of litter are discussed. Socioeconomic factors, such as the lifestyle and consumption levels of citizens and local waste management systems, are possible explanations for the low-value characteristic of marine litter. The deviation between previous data and citizen science data in this study may be caused by many factors. Based on the discussion on these factors, some suggestions for citizen science research in China are also put forward.

Human-induced temperature changes influence coastal regions, both via thermal pollution and ocean warming, which exerts profound effects on the chemistry of metals and the physiology of organisms. However, it remains unknown whether the increased temperature of discharged water or ocean warming, as a result of climate change, lead to an increase of human health risks associated with the consumption of sea foods. In this study, the influence of temperature on metal accumulation by oysters was studied in individuals collected from a coastal area affected by the thermal water discharge of the Houshi Power Plant, China. The bioaccumulation factor (BAF) and oral bioavailability (OBA) of metals in oysters was determined. Elevated temperatures led to an increase in BAF for Cu, Zn, Hg, and Cd (p < 0.05), but no change was observed for As and Pb (p > 0.05). The OBA for Cd, As, and Pb correlated positively to elevated temperatures (p < 0.05). However, for Cu and Zn, OBA was negatively correlated with increasing temperature (p < 0.05). As, Pb, and Cd in the trophically available metal (defined as a sum of heat-stable proteins, heat-denaturable proteins, and organelles) was significantly elevated at the highest temperature seawater site (site A) compared to the lowest seawater site (site B). Thus, the irregular variation of OBA for each metal may be the result of variations in the subcellular distribution of metals and the protein quality influenced by the increased temperature. Moreover, the increased temperature and increased the hazard quotient values of As and Cd (p < 0.05 for As, n = 6, p < 0.05 for Cd, n = 6), which provided an indication of the potential risks of the consumption of oysters or other seafood to future warming under climate change scenarios.

Plastic debris has become a major threat to the marine environment and wildlife. Sea turtles are particularly vulnerable, and are known to ingest plastic debris globally; however, information from Greek waters is still absent. In this study, 36 stranded dead loggerhead turtles (Caretta caretta) were collected from the Greek coastline area, and their gastrointestinal content was analysed for ingested plastic debris. Twenty-six individuals (72%) were found to have ingested plastic, with an average of 7.94 ± 3.85 (SE) plastic items per turtle. In total, 286 plastic items were counted and categorised by size, shape, colour, and polymer type. Fourier Transform Infrared Spectrometry revealed that polypropylene and polyethylene were the dominant polymer plastic types found. Results indicated a variation in plastic ingestion amongst life stages of the loggerhead specimens. This study provides evidence of plastic ingestion by loggerhead turtles in Greek waters.

Shellfish constitute an important component of human diet, especially for those living in coastal regions. Shellfish have attracted extensive attention due to high enrichment of heavy metals. The aims of this study were to investigate the levels of trace elements in shellfish from coastal waters of Shenzhen, China and to assess human intake risks. Nine elements, including chromium (Cr), copper (Cu), iron (Fe), zinc (Zn), manganese (Mn), selenium (Se), cadmium (Cd), arsenic (As) and lead (Pb) were measured in 216 shellfish samples from eight species. Their concentrations (based on wet weight) were: Cr (0.28–21.4 mg kg⁻¹), Cu (1.40–158 mg kg⁻¹), Fe (16.5–5387 mg kg⁻¹), Zn (11.1–847 mg kg⁻¹), Mn (1.33–422 mg kg⁻¹), Se (0.15–11.8 mg kg⁻¹), Cd (0.02–18.4 mg kg⁻¹), Pb (<LOQ-10.9 mg kg⁻¹) and As (2.24–95.5 mg kg⁻¹), relatively greater than those reported in shellfish from other locations of China. Crassostrea ariakensis and Babylonia areolata were found to enrich As and Cd, respectively. The target hazard quotient (THQ) values of Cd and As were more than 1, suggesting considerable health risks from the consumption of shellfish of this zone. To our knowledge, this is the first study to assess the human risk exposure to trace elements via shellfish consumption in South China.

Because oil spills frequently occur in coastal regions that serve as spawning habitat, characterizing the effects of oil in estuarine fish carries both economic and environmental importance. There is a breadth of research investigating the effects of crude oil on fish, however few studies have addressed how transcriptional responses to oil change throughout development or how these responses might be conserved across taxa. To investigate these effects, we performed RNA-seq and pathway analysis following oil exposure 1) in a single estuarine species (Cyprinodon variegatus) at three developmental time points (embryos, yolk-sack larvae, free-feeding larvae), and 2) in two ecologically similar species (C. variegatus and Fundulus grandis), immediately post-hatch (yolk-sack stage). Our results indicate that C. variegatus embryos mount a diminished transcriptional response to oil compared to later stages, and that few transcriptional responses are conserved throughout development. Pathway analysis of larval C. variegatus revealed dysregulation of similar biological processes at later larval stages, including alteration of cholesterol biosynthesis pathways, cardiac development processes, and immune functions. Our cross-species comparison showed that F. grandis exhibited a reduced transcriptional response compared to C. variegatus. Pathway analysis revealed that the two species shared similar immune and cardiac responses, however pathways related to cholesterol biosynthesis exhibited a divergent response as they were activated in C. variegatus but inhibited in F. grandis. Our results suggest that examination of larval stages may provide a more sensitive estimate of oil-impacts than examination of embryos, and challenge assumptions that ecologically comparable species respond to oil similarly.

Destructive development of suburban areas in some metropolises has exposed suburban soils to high risk of potentially toxic trace elements (PTEs) enrichment, which also threatens human and ecosystem health. This study investigated the pollution status, sources and spatial patterns of four PTEs (Pb, Cd, Cr and As) in 1805 soil samples collected from the suburbs of Shanghai in 2015. Nineteen potential sources, including: 6 soil property factors, 10 proximity factors and 3 topography factors, were selected to help explain the PTEs aggregation using logistic regression models from global and local perspectives. The statistical results of PTEs concentration revealed that Cd showed the highest pollution risk in local soils, which was followed by As. Soil property was the primary factor affecting the PTEs (except Cr) enrichment, both identified by global models and local models. The local model particularly emphasized the significant correlation between soil property and PTEs in most parts of the outer suburbs and southeastern inner suburbs. Some proximity factors such as distance to district center and water were negatively correlated with Cd pollution and some topography factors such as elevation and slope were closely related to As pollution. It is worth noting that in the coastal areas, especially Chongming Island, there were obvious PTEs depositions in the soil near the estuary. This study helps to identify the sources of anthropogenic contamination and geogenic enrichment of the four PTEs and their spatial patterns, playing an essential role in formulating regional environmental policies for coastal cities.

Marine oil spill often causes contamination of drinking water sources in coastal areas. As the use of oil dispersants has become one of the main practices in remediation of oil spill, the effect of oil dispersants on the treatment effectiveness remains unexplored. Specifically, little is known on the removal of dispersed oil from contaminated water using conventional adsorbents. This study investigated sorption behavior of three prototype activated charcoals (ACs) of different particle sizes (4–12, 12–20 and 100 mesh) for removal of dispersed oil hydrocarbons, and effects of two model oil dispersants (Corexit EC9500A and Corexit EC9527A). The oil content was measured as n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and total petroleum hydrocarbons (TPHs). Characterization results showed that the smallest AC (PAC100) offered the highest BET surface area of 889 m2/g and pore volume of 0.95 cm3/g (pHPZC = 6.1). Sorption kinetic data revealed that all three ACs can efficiently adsorb Corexit EC9500A and oil dispersed by the two dispersants (DWAO-I and DWAO-II), and the adsorption capacity followed the trend: PAC100 > GAC12 × 20 > GAC4 × 12. Sorption isotherms confirmed PAC100 showed the highest adsorption capacity for dispersed oil in DWAO-I with a Freundlich KF value of 10.90 mg/g∙(L/mg)1/n (n = 1.38). Furthermore, the presence of Corexit EC9500A showed two contrasting effects on the oil sorption, i.e., adsolubilization and solubilization depending on the dispersant concentration. Increasing solution pH from 6.0 to 9.0 and salinity from 2 to 8 wt% showed only modest effect on the sorption. The results are useful for effective treatment of dispersed oil in contaminated water and for understanding roles of oil dispersants.

Oil spills can result in changes in chemical contaminant concentrations along coastlines. When concentrations are measured along the Gulf of Mexico over time, this information can be used to evaluate oil spill shoreline exposure dates. The objective of this research was to identify more accurate oil exposure dates based on oil spill chemical concentrations changes (CCC) within sediments in coastal zones after oil spills. The results could be used to help improve oil transport models and to improve estimates of oil landings within the nearshore. The CCC method was based on separating the target coastal zone into segments and then documenting the timing of large increases in concentration for specific oil spill chemicals (OSCs) within each segment. The dataset from the Deepwater Horizon (DWH) oil spill was used to illustrate the application of the method. Some differences in exposure dates were observed between the CCC method and between oil spill trajectories. Differences may have been caused by mixing at the freshwater and sea water interface, nearshore circulation features, and the possible influence of submerged oil that is unaccounted for by oil spill trajectories. Overall, this research highlights the benefit of using an integrated approach to confirm the timing of shoreline exposure.

Hypoxia off the Changjiang Estuary (CE) and its adjacent waters is purported to be the most severe in China, attracting considerable concern from both the scientific community and the general public. Currently, continuous observations of dissolved oxygen (DO) levels covering hypoxia from its appearance to disappearance are lacking. In this study, twelve consecutive monthly cruises (from February 2015 to January 2016) were conducted. The consecutive spatiotemporal variations in hypoxia throughout the annual cycle were elucidated in detail, and the responses of annual variations in hypoxia to the different influential factors were explored. Overall, hypoxia experienced a consecutive process of expanding from south to north, then disappearing from north to south. The annual variations in hypoxia were mainly contingent on stratification variations. Among different stages, there was significant heterogeneity in the dominant factors. Specifically, low-DO waters initially appeared from the intrusion of nearshore Kuroshio branch current (NKBC), as NKBC intrusion provided a low-DO background and triggered stratification. Thereafter, stratification was enhanced and gradually expanded northward, which promoted the extension of low-DO areas. The formation of hypoxia was regionally selective, and more intense organic matter decomposition at local regions facilitated the occurrence and discontinuous distribution of hypoxia. Hypoxic zones were observed at the Changjiang bank and Zhejiang coastal region from August (most extensively at 14,800 km²) to October. Thereafter, increased vertical mixing facilitated the dissipation of hypoxia from north to south.