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At present, microplastics (MPs) pollution has attracted people's attention, and MPs in seawater have caused great harm to the marine environment. Taking Yugang Park Beach (YPB) in Zhanjiang Bay (ZJB) as the research object, we studied the spatial and temporal distribution, composition, and inventory of MPs in the bathing seawater affected by the ebb tide by filtering the bathing seawater with a 45 μm stainless steel sieve. The results showed that the average abundance of MPs in the bathing seawater was 201.3 ± 183.0 items·m−3, with the highest at mid-tide, followed by high and low tides. The size of MPs in the bathing seawater was mainly 1–2 mm, with most being white (23.5%) and green (29.8%) MPs, and the largest proportion being foam (27.5%) and fiber (29.5%). The main polymer types were polypropylene (PP), polystyrene (PS), and cellulose (CE). Correlation analysis between MP abundance and their sizes showed that the abundance of 0.33–5 mm MPs was significantly and positively correlated with their sizes (p < 0.05). The average MP inventory was 3.2 × 106 items, with the largest at high tide, followed by mid and low tides. In conclusion, these results highlighted that tidal variations were the main factor causing the uneven distribution of MPs in the bathing seawater at YPB. This study provides theoretical support for future study of MP pollution in bathing waters, and the effect of tidal variations on MPs. [ABSTRACT FROM AUTHOR]

Increasingly serious microplastic pollution in coastal areas and the ecological threats associated with plastics have attracted global attention. The frequency and intensity of typhoons have increased owing to global warming, strongly influencing the distribution and composition of microplastics in coastal ecosystems. In this study, the abundance, composition, diversity, and flux of microplastics in three estuaries and one sewage outlet in Zhanjiang Bay (ZJB) were analyzed. The average abundance of microplastics from land-based sources increased 3.6-fold from 14.19 ± 3.60 items/L before Typhoon Kompasu to 51.19 ± 28.53 items/L after the typhoon (p < 0.05). In addition, the proportion of fiber and large microplastics increased after the typhoon. In all samples, microplastics 100–330 μm in size were predominant, and blue was the most abundant color. The diversity in the color and size of microplastics increased after Typhoon Kompasu. The total daily flux of microplastics at the four stations entering ZJB was 3.95 × 1011 items before the typhoon and 9.93 × 1011 items after the typhoon, showing a 2.5-fold increase. This study demonstrated the influence of Typhoon Kompasu on microplastics from land-based sources of ZJB coastal waters and provided vital data for further study on MP pollution in coastal water ecosystems and the impact of typhoons on microplastics. [ABSTRACT FROM AUTHOR]

The stratigraphic-diffusive type of gas hydrate system is formed by microbial methane produced in a shallow slope space when flowing laterally into hydrate stable zones and is worth studying for both energy supply and academic understanding. A deposition production model matching the vertical and lateral seabed morphological characteristics was constructed to show the accumulation process, layer timing sequence, and reservoir quality of the stratigraphic-diffusive hydrate system in the Dongsha slope sediments since the Pleistocene. Six representative key system factors at three selected moments (1.5 Ma, 700 ka B.P., and at present) have been exhibited during debris is continuously accumulating. The coexistence of the hydrate decomposition in the lower part and the formation in the upper part, and the uneven distribution of hydrates within the slope sediment surface are explained clearly. By comparing four geological cases with diverse environments, it is shown that the diffusive hydrate system is likely to develop into moderate geological conditions. The most powerful carbon fixation ability in this system was quantified within the time range of 100−50 ka B.P. Finally, it was verified that residual methane would converge near the seafloor interface and then eventually overflow out of the seabed into the seawater. [ABSTRACT FROM AUTHOR]