Dark background-surface enhanced Raman spectroscopic detection of nanoplastics: Thermofluidic strategy.

This study aims to develop a cost-effective and time-efficient method for detecting nanoplastics, which have recently garnered significant attention due to their potential harmful impact on the water environment (XiaoZhi, 2021; Gigault et al., 2021; Mitrano et al., 2021; Ferreira et al., 2019). Although several techniques are available to accumulate data on microplastics, there is currently no universally accepted analytical technique for detecting nanoplastics (Gigault et al., 2021; Mitrano et al., 2021; Mitrano et al., 2019; Cai et al., 2021a; Allen et al., 2022). In this study, we have developed a substrate that exhibits Surface-enhanced Raman scattering (SERS) (Zhou et al., 2021; Lv et al., 2020; Lê et al., 2021; Hu et al., 2022; Chang et al., 2022; Yang et al., 2022; Xu et al., 2020; Jeon et al., 2021; Lee and Fang, 2022; Vélez-Escamilla and Contreras-Torres, 2022; Liu et al., 2022; Xie et al., 2023) activity over a large area and a dark background in optical (darkfield mode) vision, enabling the detection of sparkling nanoplastics on the substrate. This darkfield-based strategy allows for the point-by-point detection of single nanoplastics, offering cost and time-saving advantages over other resource-intensive analytical techniques. Our findings reveal the presence of PP nanoplastics in commonly used laboratory equipment, individual PE nanoplastics from a hot water-contained commercial paper cup, and the first detection of natural nanoplastics in coastal seawater. We believe that this technique will have a universal application in establishing a global map of nanoplastics and advancing our understanding of the environmental life cycle of plastics.

Polyurethane Sponge with a Modified Specific Surface for Repeatable Oil-Water Separation.

Oil spill accidents contaminate the oceanic environment and cause economic distress, and they continue to occur. Many methods have been developed to restore waters contaminated with spilled oil. However, still most commercially available methods are not environmentally or economically sustainable solutions. Therefore, there is a need for the development of sustainable materials with running water treatment capabilities. In recent years, a polyurethane (PU) sponge-based adsorbent has been reported as an oil-water separation and reusable adsorbent. This is because the porous 3D structure of the PU sponge provides a large surface area. However, as the PU sponge has a carboxyl group and an amino group, it exhibits hydrophilicity, so surface modification is essential for oil-water separation. Therefore, to modify the surface of PU to have hydrophobic/oleophilic properties, a hydrophobic/oleophilic adsorbent (HOA) was prepared using graphite and polydimethylsiloxane. On the basis of this, a PU sponge, a porous material, was used to manufacture an adsorbent that can be used in a sustainable and environmentally friendly way. The prepared HOA can selectively adsorb water or oil and can be reused. Furthermore, continuous oil-water separation is possible through a simple flow of fluid. Therefore, it is confirmed that the studied HOA can have great potential for ocean restoration in the future as an adsorbent that mitigates the disadvantages of the currently commercialized method.

Effects of seasonal variations on sediment-plume streaks from dredging operations.

When mixtures of aggregates and water dredged from the seabed are discharged at the surface into the adjacent water from a barge, coarse sediments sink immediately and fine sediments are suspended forming a plume. Recently, elongated plumes of fine sediment were observed by satellites near a dredging location on the continental shelf. Such plume streaks were longer in certain conditions with seasonality than expected or reported previously. Therefore, the present work studied the appearance of sediment plume with field measurements and numerical simulations and explains the seasonally varying restoring force and thicknesses of the surface mixed layer resulting from the vertical density distribution near the surface, along with mixing by hydrodynamic process. The resulting mixtures, after vertical restoring and mixing with the surroundings, determine the horizontal transport of suspended sediments. A numerical model successfully reproduced and explained the results from field measurements and satellite images along with the seasonal variations.

Exploring the Impacts of Anthropogenic Disturbance on Seawater and Sediment Microbial Communities in Korean Coastal Waters Using Metagenomics Analysis.

The coastal ecosystems are considered as one of the most dynamic and vulnerable environments under various anthropogenic developments and the effects of climate change. Variations in the composition and diversity of microbial communities may be a good indicator for determining whether the marine ecosystems are affected by complex forcing stressors. DNA sequence-based metagenomics has recently emerged as a promising tool for analyzing the structure and diversity of microbial communities based on environmental DNA (eDNA). However, few studies have so far been performed using this approach to assess the impacts of human activities on the microbial communities in marine systems. In this study, using metagenomic DNA sequencing (16S ribosomal RNA gene), we analyzed and compared seawater and sediment communities between sand mining and control (natural) sites in southern coastal waters of Korea to assess whether anthropogenic activities have significantly affected the microbial communities. The sand mining sites harbored considerably lower levels of microbial diversities in the surface seawater community during spring compared with control sites. Moreover, the sand mining areas had distinct microbial taxonomic group compositions, particularly during spring season. The microbial groups detected solely in the sediment load/dredging areas (e.g., Marinobacter, Alcanivorax, Novosphingobium) are known to be involved in degradation of toxic chemicals such as hydrocarbon, oil, and aromatic compounds, and they also contain potential pathogens. This study highlights the versatility of metagenomics in monitoring and diagnosing the impacts of human disturbance on the environmental health of marine ecosystems from eDNA.