The presence of microplastics (MPs) in marine environments has become increasingly apparent. Owing to the lack of effective solid waste management, Indonesia is the second largest producer of ocean ...plastic waste after China. Currently, information about pollution of MPs in the sediments of East Surabaya, Indonesia, is not available, and this issue is addressed in this study for the first time. Sediment samples were collected from 16 sampling sites along urban and mangrove coastal areas. MPs were observed in most of the sampling sites, with abundances ranging from ND (not detected) to 598 items/kg. MP shapes constituted fragments (30%), foam (28%), granules (22%), and fibers (20%). The 500-1000 µm fraction was the dominant size of MPs. Polypropylene was the major polymer constituent, followed by high-density polyethylene and polyethylene. Findings from Spearman's correlation coefficients, principal component analysis, and hierarchical cluster analysis reveal that the spatial pattern of MPs is closely related to coastal characteristics and population density. MPs in different coastal regions were assessed by the polymer risk index. Results reveal that coastal areas in the Bulak district exhibit the highest risk. Our results confirm the prevalence of MPs as anthropogenic pollutants in East Surabaya and highlight the importance of management action and education on environmental protection for the mitigation of MP pollution.
The substantial increase in plastic pollution in marine ecosystems raises concerns about its adverse impacts on the microbial community. Microorganisms (bacteria, phytoplankton) are important ...producers of exopolymeric substances (EPS), which govern the processes of marine organic aggregate formation, microbial colonization, and pollutant mobility. Until now, the effects of nano- and micro-plastics on characteristics of EPS composition have received little attention. This study investigated EPS secretion by four phytoplankton species following exposure to various concentrations of polystyrene nano- and microplastics (55 nm nanoparticles; 1 and 6 μm microparticles). The 55 nm nanoparticles induced less growth/survival (determined on a DNA basis) and produced EPS with higher protein-to-carbohydrate (P/C) ratios than the exposure to microplastic particles. The amount of DNA from the four marine phytoplankton showed a higher negative linear correlation with increasing P/C ratios, especially in response to nanoplastic exposure. These results provide evidence that marine phytoplankton are quite sensitive to smaller-sized plastics and actively modify their EPS chemical composition to cope with the stress from pollution. Furthermore, the release of protein-rich EPS was found to facilitate aggregate formation and surface modification of plastic particles, thereby affecting their fate and colonization. Overall, this work offers new insights into the potential harm of different-sized plastic particles and a better understanding of the responding mechanism of marine phytoplankton for plastic pollution. The data also provide needed information about the fate of marine plastics and biogenic aggregation and scavenging processes.
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•High levels of nano-/micro-plastics can decrease the survival of phytoplankton.•High concentrations of nano-/micro-plastics can trigger protein-rich EPS release.•A negative correlation between cell survival and P/C ratio was established.•Protein-rich EPS can facilitate the aggregate formation.
•Microplastics can be transferred by bubble bursting at the water–air interface.•First study on plastic-gel enhancement of microplastic transfer from water to air.•High salinity, gel concentration, ...and viscosity induced microplastic transfer to air.•Plastic-gel formation via cation-linking bridges modulates microplastic transfer capacity.
The pervasiveness of microplastics (MPs) in global oceans is raising concerns about their adverse impacts on ecosystems. The mechanistic understanding of MP transport is critical for evaluating its fate, flux, and ecological risks specifically. Currently, bubble bursting is believed to represent an important route for MP transfer from sea surfaces to the atmosphere. However, the detailed mechanisms of the complex physico-chemical interactions between MPs, water composition, and gel particles in the air–sea interface remain unknown. Our results suggested three steps for MP transfer between air–sea phases: (1) MPs incorporating into gel aggregates in the water column; (2) further accumulation of plastic-gel aggregate in the surface layer phase; finally (3) ejection of aggregates from the sea when bubbles of trapped air rise to the surface and burst. The water composition (e.g., high salinity, gel concentration and viscosity) can modulate plastic-gel aggregation and subsequent transport from water to the atmosphere. The possible mechanism may be closely tied to the formation of plastic-gel via cation-linking bridges, thereby enhancing plastic-gel ejection into air. Collectively, this work offers unique insights into the role of marine plastic-gels in determining MP fate and transport, especially at air–sea interfaces. The data also provide a better understanding of the corresponding mechanism that may explain the fates of missing plastics in the ocean.
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Organic particle dynamics in the surface ocean plays a critical part in the marine carbon cycle. Aggregation of marine organic particles drives their downward transport to support various marine ...organisms on their transit to the sediments. Extracellular polymeric substances (EPS) from various microbes are a major contributor to the oceanic organic particle pool. The stickiness of EPS is expected to play a determining role in the aggregation process of particles; however, stickiness parameters are usually indirectly estimated through data fitting without direct assessment. Here a magnetic tweezer method was developed to quantitatively assess the stickiness of three model EPS produced by: Amphora sp., (diatom), Emiliania huxleyi (coccolithophore), and Sagittula stellata (bacteria), under different in vitro environmental conditions (salinity or EDTA complexed cations) and surface matrices (EPS-EPS and bare glass). Our results showed the stickiness of three microbial EPS decreasing for S. stellata > E. huxleyi > Amphora sp., in line with their decreasing protein-to-carbohydrate (P/C) ratios (related to their relative hydrophobicity). The data not only emphasize the importance of hydrophobicity on EPS stickiness, but also demonstrates that salinity and the nature of the substrate surface can influence the stickiness. Furthermore, we investigated stickiness between various types of EPS, and the observed selective stickiness of EPS between species may shed light on the interactions among heterogeneous marine microorganisms. Overall, this newly developed system provides a platform to assess the EPS stickiness to advance our understanding of the aggregation and sedimentation process of organic particles that are critical for the fate of organic carbon as well as for biofilm formation and microbial colonization of surfaces in the ocean.
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•A magnetic tweezer-based system was developed to assess the stickiness of EPS.•EPS stickiness is closely related to protein/carbohydrate ratio.•Ca2+ crosslinking and hydrophobic interactions contribute to EPS stickiness.
Microplastics (MPs) are ubiquitous in oceans. Their transboundary transport and fate have aroused global attention. Taiwan is located close to the western boundary current-Kuroshio, is an excellent ...location to study of MP mobility in the global current and Pacific Garbage Patch. This study is the first investigation to understand the microplastic contamination from Taiwan to the Kuroshio. MP concentrations in the area varied from N.D. to 0.15 items m−3, with an average concentration of 0.05 ± 0.03 items m−3. The majority of MPs were polypropylene, polyethylene, polyethylene and terephthalate. We found two MP hotspots near the coastal zone. One additional hotspot was also identified in the “pristine” Kuroshio suggesting rivers and local currents may play critical roles in transporting or injecting MPs from Taiwan into the North Pacific Gyre. These findings suggest that marine environments are altered by anthropogenic disposal and provide needed data for modelling and prediction of MPs.
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•First study on microplastics (MPs) in the Kuroshio off eastern Taiwan.•The higher MP levels were found at near river outlets and area with complex current.•Microplastics in the Kuroshio are transported by local currents.•The majority of MPs consisted of PP, PE, PET, and PS.
•Different types of DOC polymers forming microgel were compared.•The assembly effectiveness of marine DOC was much higher than riverine DOC.•Types and sources of DOC polymers may control the aquatic ...microgel abundance.•An alternative route for CDOM and heavy metals removal is presented.•Ecological risk and fate assessments of pollutants may consider the microgel phase.
We use riverine and marine dissolved organic carbon (DOC) polymers to examine their aggregation behavior, and to evaluate the roles of microgel formation in scavenging of chromophoric dissolved organic matter (CDOM) and heavy metals in a river-sea system. Our results indicate that riverine and marine microgels did not exhibit very much difference in size and self-assembly curve; however, the assembly effectiveness (microgel/DOC) of marine samples was much higher than riverine. Instead of concentration of DOC, other factors such as types and sources of DOC polymers may control the microgel abundance in aquatic environments. After filtering water samples (microgels removed), the CDOM and selected metals (Cu, Ni, Mn) in the filtrate were quantified. CDOM and metals were concurrently removed to an extent via DOC polymer re-aggregation, which also suggested that the microgels had sequestering capability in CDOM and metals. This finding provides an alternative route for CDOM and heavy metals removal from the water column. As such the process of re-aggregation into microgels should then be considered besides traditional phase partitioning in the assessment of the ecological risk and fate of hazardous materials.
With continuous population and economic growth in the 21
century, plastic pollution is a major global issue. However, the health concern of microplastics/ nanoplastics (MPs/NPs) decomposed from ...plastic wastes has drawn public attention only in the recent decade. This article summarizes recent works dedicated to understanding the impact of MPs/NPs on the liver-the largest digestive organ, which is one of the primary routes that MPs/NPs enter human bodies. The interrelated mechanisms including oxidative stress, hepatocyte energy re-distribution, cell death and autophagy, as well as immune responses and inflammation, were also featured. In addition, the disturbance of microbiome and gut-liver axis, and the association with clinical diseases such as metabolic dysfunction-associated fatty liver disease, steatohepatitis, liver fibrosis, and cirrhosis were briefly discussed. Finally, we discussed potential directions in regard to this trending topic, highlighted current challenges in research, and proposed possible solutions.
The incineration of municipal solid waste has been important in waste management, but it raises another environmental issue concerning residue treatment. This study describes an innovative use of ...naturally aged incineration bottom ash (AIBA) as an alternative substrate for horizontal subsurface flow (HSSF) constructed wetlands (CW). Although experimental results from a period lasting for 396 days only revealed slightly higher removal ratios in HSSF with AIBA (HSSF-E) than in HSSF-traditional pebble beds (HSSF-C), increasing from 67% to 76% for BOD, 44%–51% for TKN, 47%–54% for NH3-N, and 44%–52% for TN. The data indicate that the use of AIBA in HSSF CW can achieves a certain removal efficiency of BOD and nitrogen species. Interestingly, the total phosphorus removal rates also increased significantly from 20% in HSSF-C to 36% in HSSF-E. These observations on the use of AIBA in HSSF CW confirmed that AIBA is a suitable alternative for use as a substrate for HSSF CWs and identified an additional way to reuse incineration bottom ash. Design criteria for a CW using AIBA as a partial substrate is proposed to improve the pollutant removal performance of HSSF CWs.
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•Incineration bottom ashes can as a substrate for constructed wetlands (CW).•Pollutant removal rates in ash bed were higher than in traditional pebble bed.•Ash bed also exhibited higher removal capacity of total phosphorus.•All leached metals from bottom ash were below the government requirement.
The transport and ultimate fate of per- and polyfluoroalkyl substances (PFASs) are generally considered to be influenced by partitioning behavior between water, suspended particulate matters (SPM), ...and sediments. This study examined the distribution and partitioning of the PFASs in the water, SPM, and sediments in a densely populated urban river-coastal system. The total concentrations of eight PFASs (∑8 PFASs) in the water phase, SPM, and sediments varied from 0.59 to 7.40 ng/L, 0.54 to 9.08 ng/g, and 0.05 to 0.13 ng/g, respectively. The PFAS concentrations in the water and SPM phase decreased as the salinity increased, confirming contaminant inputs from the upstream of the river to the estuary zone. Notably, the positive correlation between SPM-bound PFASs and transparent exopolymer particles (TEPs) content, providing first evidence that TEPs may accumulate and concentrate more PFASs on the SPM. Collectively, this results offers useful information about roles of TEPs in determining environmental fate of PFASs.
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•First study on PFASs levels in the most urbanized river-coastal system of Taiwan•The PFAS contamination in the water, SPM, and sediments was investigated.•Confirmed a role for rivers in transporting PFASs to coastal zones•The dominant compounds of PFASs were PFOA, PFOS, and PFHpA in this area.•TEPs may accumulate and concentrate more PFASs on the SPM.
The pervasive presence of plastic waste in the aquatic environment is widely viewed as one of the most serious environmental challenges for current and future generations. Microplastics ultimately ...degrade into nano and smaller-sizes. In turn, their biological and ecological impacts become more complicated and ambiguous. Nano-plastic particles travel from freshwater systems to estuarine and oceanic regions, during which they can interact with dissolved organic matter (DOM) to form microgels. Microgel formation is ubiquitous in aquatic systems, serving as a shunt between DOM and particulate organic matter (POM), as well as playing key roles in particle aggregation/sedimentation and pollutant transport. Currently the influences and mechanisms of the aggregation behavior and environmental fate of nano-plastics in different aquatic environments is poorly understood. Here, we report that 25 nm polystyrene nano-particles in lake and river water can promote POM (microgel) formation and accelerate the DOM–POM transition. We also adjusted various salinities of water samples to simulate scenarios based on plastic transport in waters flowing from rivers to seas. The results indicate polystyrene nanoparticles can interact with organic matter to form large organic particles, which may undergo further settling in response to specific salinity levels. Polystyrene-induced microgel formation appears to involve the hydrophobic interactions between plastics and DOM. Our data provides much needed information for modeling and understanding the retention and sedimentation of nano-plastics. We show that nano-plastics alter the DOM–POM shunt to cause unanticipated perturbations in the functionality of aquatic ecosystems.
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•Nano-plastics can interact with dissolved organic matter (DOM) to form microgels.•Nano-plastics can increase the microgel abundance at specific salinities•The facilitation of microgel formation involves DOM–plastics crosslinking via hydrophobic interactions.
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