•Sub-surface rubbish items intercepted in fyke-nets in the River Thames.•The trapping of 8490, mainly plastic, items during a three month period.•Over 20% of rubbish items were components of sanitary ...products.•Most contaminated sites were in the vicinity of sewage treatment works.•Evidence for significant sub-surface transport of rubbish in the Thames Estuary.
Although contamination of the marine ecosystems by plastics is becoming recognised as a serious pollution problem, there are few studies that demonstrate the contribution made by freshwater catchments. Over a three month period from September to December 2012, at seven localities in the upper Thames estuary, 8490 submerged plastic items were intercepted in eel fyke nets anchored to the river bed. Whilst there were significant differences in the numbers of items at these locations, the majority were some type of plastic. Additionally in excess of 20% of the litter items were components of sanitary products. The most contaminated sites were in the vicinity of sewage treatment works. While floating litter is visible, this study also demonstrates that a large unseen volume of submerged plastic is flowing into the marine environment. It is therefore important that this sub-surface component is considered when assessing plastic pollution input into the sea.
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•We quantified pelagic microplastic pollution in Lake Hovsgol, Mongolia.•Lake Hovsgol is more polluted with microplastics than Lakes Huron and Superior.•Microplastics came from ...consumer goods; no microbeads/few pellets were observed.•Microplastics were sourced from population centers and distributed by the winds.•Without waste management, even small populations can heavily pollute large lakes.
Despite the large and growing literature on microplastics in the ocean, little information exists on microplastics in freshwater systems. This study is the first to evaluate the abundance, distribution, and composition of pelagic microplastic pollution in a large, remote, mountain lake. We quantified pelagic microplastics and shoreline anthropogenic debris in Lake Hovsgol, Mongolia. With an average microplastic density of 20,264 particles km−2, Lake Hovsgol is more heavily polluted with microplastics than the more developed Lakes Huron and Superior in the Laurentian Great Lakes. Fragments and films were the most abundant microplastic types; no plastic microbeads and few pellets were observed. Household plastics dominated the shoreline debris and were comprised largely of plastic bottles, fishing gear, and bags. Microplastic density decreased with distance from the southwestern shore, the most populated and accessible section of the park, and was distributed by the prevailing winds. These results demonstrate that without proper waste management, low-density populations can heavily pollute freshwater systems with consumer plastics.
•Plastic pollution accumulates in the Laurentian Great Lakes of the United States.•Using SEM/EDS, misidentification of coal ash as microplastic was corrected.•Microplastics from the Great Lakes are ...suspected to be microbeads.
Neuston samples were collected at 21 stations during an ∼700 nautical mile (∼1300km) expedition in July 2012 in the Laurentian Great Lakes of the United States using a 333μm mesh manta trawl and analyzed for plastic debris. Although the average abundance was approximately 43,000 microplastic particles/km2, station 20, downstream from two major cities, contained over 466,000particles/km2, greater than all other stations combined. SEM analysis determined nearly 20% of particles less than 1mm, which were initially identified as microplastic by visual observation, were aluminum silicate from coal ash. Many microplastic particles were multi-colored spheres, which were compared to, and are suspected to be, microbeads from consumer products containing microplastic particles of similar size, shape, texture and composition. The presence of microplastics and coal ash in these surface samples, which were most abundant where lake currents converge, are likely from nearby urban effluent and coal burning power plants.
•The quantity and composition of suspended microplastics are reported for the first time in China.•Microplastics (0.5–5mm) constituted more than 90% of total plastics by number of ...items.•Microplastics concentrations were spatially variable in the Yangtze Estuary.•Large rivers are contributed to the high MP abundances in the adjacent marine environment.•The most abundant plastics were fibres, while plastic spherules were rarely found.
Levels of microplastics (MPs) in China are completely unknown. This study characterizes suspended MPs quantitatively and qualitatively for the Yangtze Estuary and East China Sea. MPs were extracted via a floatation method. MPs were counted and categorized according to shape and size under a stereomicroscope. The MP densities were 4137.3±2461.5 and 0.167±0.138n/m3, respectively, in the estuarine and the sea samples. Plastic abundances varied significantly in the estuary. Higher densities in three sea trawls confirmed that rivers were the important sources of MP to the marine environment. Plastic particles (>5mm) were observed with a maximum size of 12.46mm, but MPs (0.5–5mm) constituted more than 90% by number of items. The most frequent geometries were fibres, followed by granules and films. Plastic spherules occurred sparsely. Transparent and coloured plastics comprised the majority of the particles. This study provides clues in understanding the fate and potential sources of MPs.
Microplastics represent an increasing source of anthropogenic contamination in aquatic environments, where they may also act as scavengers and transporters of persistent organic pollutants. As ...estuaries are amongst the most productive aquatic systems, it is important to understand sorption behaviour and transport of persistent organic pollutants (POPs) by microplastics along estuarine gradients. The effects of salinity sorption equilibrium kinetics on the distribution coefficients (Kd) of phenanthrene (Phe) and 4,4′-DDT, onto polyvinyl chloride (PVC) and onto polyethylene (PE) were therefore investigated. A salinity gradient representing freshwater, estuarine and marine conditions, with salinities corresponding to 0 (MilliQ water, 690 μS/cm), 8.8, 17.5, 26.3 and 35 was used. Salinity had no significant effect on the time required to reach equilibrium onto PVC or PE and neither did it affect desorption rates of contaminants from plastics. Although salinity had no effect on sorption capacity of Phe onto plastics, a slight decrease in sorption capacity was observed for DDT with salinity. Salinity had little effect on sorption behaviour and POP/plastic combination was shown to be a more important factor. Transport of Phe and DDT from riverine to brackish and marine waters by plastic is therefore likely to be much more dependent on the aqueous POP concentration than on salinity. The physical characteristics of the polymer and local environmental conditions (e.g. plastic density, particle residence time in estuaries) will affect the physical transport of contaminated plastics. A transport model of POPs by microplastics under estuarine conditions is proposed. Transport of Phe and DDT by PVC and PE from fresh and brackish water toward fully marine conditions was the most likely net direction for contaminant transport and followed the order: Phe-PE >> DDT-PVC = DDT-PE >> Phe-PVC.
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•Salinity effect was investigated on sorption/desorption of POPs onto microplastics.•Little effect on sorption and no effect on their desorption rates was observed.•Transport of POPs will largely depend on their concentration in each compartment.•A transport model of POPs onto microplastics was proposed.•Transport followed the order: Phe-PE >> DDT-PVC = DDT-PE >> Phe-PVC.
The world's largest trans-regional macroalgal blooms during 2008–2012 occurred in the Yellow Sea, China. This review addresses the causes, development and future challenges in this unique case. ...Satellite imagery and field observations showed that the macroalgal blooms in the Yellow Sea originated from the coast of Jiangsu province and that favorable geographic and oceanographic conditions brought the green macroalgae from the coast offshore. Optimal temperature, light, nutrients and wind contributed to the formation and transport of the massive bloom north into the Yellow Sea and its deposition onshore along the coast of Shandong province. Morphological and genetic evidence demonstrated that the species involved was Ulva prolifera, a fouling green commonly found growing on structures provided by facilities of Porphyra aquaculture. Large scale Porphyra aquaculture (covering >20,000 ha) along the Jiangsu coast thus hypothetically provided a nursery bed for the original biomass of U. prolifera. Porphyra growers remove U. prolifera from the mariculture rafts, and the cleaning releases about 5000 wet weight tonnes of green algae into the water column along the coast of Jiangsu province; the biomass then is dispersed by hydrographic forcing, and takes advantage of rather high nutrient supply and suitable temperatures to grow to impressive levels. Certain biological traits of U. prolifera —efficient photosynthesis, rapid growth rates, high capacity for nutrient uptake, and diverse reproductive systems— allowed growth of the original 5000 tonnes of U. prolifera biomass into more than one million tonnes of biomass in just two months. The proliferation of U. prolifera in the Yellow Sea resulted from a complex contingency of circumstances, including human activity (eutrophication by release of nutrients from wastewater, agriculture, and aquaculture), natural geographic and hydrodynamic conditions (current, wind) and the key organism's biological attributes. Better understanding of the complex biological–chemical–physical interactions in coastal ecosystems and the development of an effective integrated coastal zone management with consideration of scientific, social and political implications are critical to solving the conflicts between human activity and nature.
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•Summaries various studies on the world's largest green-tide in the Yellow Sea.•Indicates a multidisciplinary approach to understand the formation of green-tide.•Suggests an integrated management considering scientific, social and political implications.
•Anthropogenic litter was surveyed at riversides and on beaches near river mouths.•Litter composition and abundance patterns were compared between the two environments.•Rivers transport litter to ...beaches and wind and water currents determine its deposition.•Litter composition is characteristic of each river and attributable to human influences.•Strongly persistent, buoyant items make up the main share of riverine and beach litter.
Composition and abundance of persistent buoyant litter (plastics, polystyrene and manufactured wood) were investigated at riversides and on adjacent coastal beaches of four rivers flowing into the SE Pacific Ocean. Persistent buoyant litter made up the main share of litter at riversides (36–82%) and on coastal beaches near the river mouths (67–86%). The characteristic litter composition of each river is attributable to human influences along its course. Riverine litter items were deposited to both sides of the river mouths on coastal beaches, and their abundance generally declined with distance from the river mouth. However, maximum litter accumulations were often found on beaches north of the river mouth, suggesting a long-term influence of the prevailing equatorward low-level jet along the Chilean coast. The results confirm that riverine transport has an important impact on litter abundances on coastal beaches.
•Microplastics were identified in seven intertidal mangrove habitats of Singapore.•Majority of microplastics identified were fibrous and less than 20μm.•Polyethylene, polypropylene, nylon and PVC ...were identified using ATR–FTIR.
The prevalence of microplastics was studied in seven intertidal mangroves habitats of Singapore. Microplastics were extracted from mangrove sediments via a floatation method, and then counted and categorized according to particle shape and size. Representative microplastics from Berlayar Creek, Sungei Buloh, Pasir Ris and Lim Chu Kang were isolated for polymer identification using Attenuated Total Reflectance–Fourier Transform Infrared (ATR–FTIR) spectroscopy. Microplastics were identified in all seven habitats, with the highest concentration found in sediments at Lim Chu Kang in the northwest of Singapore. The majority of microplastics were fibrous and smaller than 20μm. A total of four polymer types were identified, including polyethylene, polypropylene, nylon and polyvinyl chloride. The relationship between abundance of microplastics and sediment grain size was also investigated, but no relationship was apparent. The presence of microplastics is likely due to the degradation of marine plastic debris accumulating in the mangroves.
•Sedimentary PAHs in Guan River Estuary were investigated for the first time.•PAH concentrations were low in comparison with other estuaries around the world.•PAH concentrations appeared to be ...negatively correlated with sediment grain size.•Sedimentary PAHs in GRE mainly originated from pyrolytic sources.•Sedimentary PAHs in GRE indicated low negative effects except FLO.
The contamination of surface sediments in Guan River Estuary, China, by polycyclic aromatic hydrocarbons (PAHs) has been fully investigated. Total concentrations of 21 PAHs ranged from 90 to 218ng/g with an average of 132.7ng/g, which is relatively low in comparison with other estuaries around the world. PAH concentrations appeared to be positively correlated with clay content and negatively correlated with sediment grain size. Source identification implied that the PAHs originated mainly from pyrolytic sources. However, source patterns may be continuously changed to a petrogenic origin due to the heavy ship traffic and continuous discharge of oily sewage in this area. The PAH levels were also compared with international Sediments Quality Guidelines and Sediments Quality Criteria, and the results indicated low negative effects for most individual PAHs. However, toxic effects related to FLO would occur occasionally in most locations in the estuary.
•Field and historical data on nutrients and HABs from 1950s to 2007s.•Variations of dissolved inorganic nutrients in the Changjiang River Estuary.•The characteristics of HABs in the past fifty ...years.•The importance of nutrient fluxes and DO variation in HABs in research area.•Nutrient composition and phytoplankton community were also analyzed.
Based on observations collected during 15 cruises from 2002 to 2007 and on historical data, annual and seasonal variations in dissolved inorganic nutrients in the Changjiang (Yangtze) River estuary and the adjacent area were investigated. The importance of nutrients and nutrient fluxes to Harmful Algal Blooms (HABs) in the East China Sea (ECS) was also studied. The results showed an increasing trend in dissolved inorganic nitrogen (DIN) over the past fifty years. The changes in the PO4-P concentration fluctuated from 1959 to 2000, but the level has been almost stable since then. By contrast, the SiO3-Si concentrations decreased significantly over the past fifty years. Regarding seasonal variations, nutrients usually exhibited high values during autumn and winter, and the lowest values occurred in mid-summer. A strong positive relationship was observed between the DIN and PO4-P concentrations and the frequency or scale of HABs, indicating that eutrophication played a crucial role in the occurrence of HABs. As for nutrient fluxes, DIN and PO4-P fluxes have climbed sharply since 1980. In the ECS, the DIN increased sharply, but PO4-P concentrations only changed slightly. The increased nutrient discharges, especially DIN, could also have caused the strong increase in the frequency and area of HABs. The areas of hypoxic bottom water off the Changjiang River estuary presented an increasing trend over the past fifty years, which may also be attributable to eutrophication. Changes in the nutrient composition were also investigated in the present study. The N/P ratio increased dramatically over the past fifty years, while the Si/N ratio decreased. The percentage of diatoms decreased from 99% to 73%, while dinoflagellates increased from less than 1% to over 25% during the past fifty years. Therefore, long-term changes in nutrients, especially excess DIN and increasing N/P, could be responsible for the shift in the phytoplankton community structure.
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