Enrichment and ecological risks of microplastics in mangroves of southern Hainan Island, China.

Mangroves have recently been identified as one of the most threatened ecosystems by microplastics (MPs) pollution from terrestrial and marine sources, while little is known regarding the MPs enrichment, influencing factors and associated ecological risks in mangroves. The present investigation aims to evaluate the accumulation, characteristics, and ecological risks of MPs in various environmental matrices from three mangroves of southern Hainan Island during dry and wet seasons. The results revealed the prevalence of MPs pollution in the surface seawater and sediment from all studied mangroves during two seasons, where the highest MPs abundance was observed at Sanyahe mangrove. The abundance of MPs varied considerably in surface seawater by seasons and were distinctly modulated by rhizosphere effect. The characteristics of MPs also exhibited some pronounced variations across mangroves, seasons and environmental compartments, but the detected MPs were dominated by fiber-shaped, transparent-colored, and smaller-sized (100-500 µm) MPs. The most prevalent polymer types were polypropylene, polyethylene terephthalate and polyethylene. Further analyses revealed positive correlations between MPs abundance and contents of nutrient salts in surface seawater but negative relationships between MPs abundance and water physicochemical properties, including temperature, salinity, pH and conductivity (p < 0.05). The joint use of three evaluation models indicated MPs posed varying degrees of ecological risks to all studied mangroves, whereas Sanyahe mangrove exhibited the highest ecological risk of MPs pollution. This study provided new insights into the spatial-seasonal variations, influencing factors and risk assessment of MPs in mangroves, which would be helpful for source tracing, pollution monitoring and policy formulation.

Improved hydrogen production from pharmaceutical intermediate wastewater in an anaerobic maifanite-immobilized sludge reactor.

A novel anaerobic maifanite-immobilized sludge reactor (AMSR) was employed to investigate the feasibility and performance of continuous hydrogen production for the treatment of pharmaceutical intermediate wastewater (PIW) at different organic loading rates (OLR) (from 12 to 96 g COD L-1 d-1) according to changes in the hydraulic retention time (HRT). A reactor without maifanite was also employed as a control. The results indicate that maifanite accelerates granular sludge formation and the AMSR presents more efficient and stable performance than the control in terms of the hydrogen production rate. In the AMSR, the highest hydrogen production rate of 11.2 ± 0.4 mmol L-1 h-1 was achieved at an optimum OLR of 72 g COD L-1 d-1. The main metabolic route for hydrogen production was ethanol-type fermentation, which was reflected in the relative abundance of E. harbinense, which was dominant for all of the OLRs. The maximum energy conversion efficiency in the dual production of hydrogen and ethanol was determined to be 24.5 kJ L-1 h-1 at an OLR of 72 g COD L-1 d-1.

[Distribution Characteristics of Microplastics in Qingdao Coastal Beaches].

Microplastics (MPs, plastic fibers, debris, or particles that are generally smaller than 5 mm in diameter) can serve as carriers for hazardous substances, which are ingested by organisms in the ocean and can affect their growth and metabolism. Moreover, MPs will spread with ocean currents, and MP pollution has become a global problem. In this study, the MP abundance distribution of four typical beaches near the coast of Qingdao was studied by the combination of ordinary microscope and fluorescence microscope methods. In addition, the distribution of MPs collected from various beaches in different particle size ranges, shapes, and chemical compositions was discussed. Abundances on the sea surface varied between 5.05×103 particles·m-3 and 1.25×104 particles·m-3, and the concentration of MPs in sand varied between 1.91×103 particles·m-2 and 4.35×103 particles·m-2, with no significant differences detected among the four beaches examined. The results show the pervasiveness of MP pollution in coastal environments of Qingdao. The size of particles found in this study ranged from 5 mm to 50 µm, and increases in abundance were detected with the decreasing particle size. Polypropylene (PP), polyethylene (PE), polystyrene (PS), polyethylene terephthalate (PET), polyvinyl chloride (PVC), 96% polystyrene+4% butadiene copolymer (SB), polymethyl acrylate (PMA), and polyamide (PA) were present in seawater in coastal environments of Qingdao, and compared with the seawater samples, no PA or PMA were found in sand. Research results indicated that fiber was dominant in seawater and sand. MPs in the sand were similar to those in seawater in terms of the particle size, shape, and composition, thus indicating that the seawater and sand of the bathing beaches in Qingdao may have the same pollution sources, e. g., the packaging industry, clothing textile industry, and tourism. This paper studies the distribution and sources of MPs in the bathing beaches of Qingdao, and it provides basic data for research and supervision of environmental MP pollution in Chinese coastal zones.