Microplastics pollution in inland freshwaters of China: A case study in urban surface waters of Wuhan, China

Distribution and risk assessment of microplastics in Liujiaxia Reservoir on the upper Yellow River

Abundance and characteristics of microplastics in the surface water and sediment of parks in Xi'an city, Northwest China

Characterization and risk assessment of microplastics in laver from the Yueqing Bay

In recent years, microplastics have emerged as a new marine pollutant and have attracted wide research attention. As the main activity areas of human beings in the coastal environment, gulfs have always been the hotspots of marine pollution. However, the distribution of microplastics in most small and medium-sized coastal environments has been rarely reported in China. To understand the characteristics of microplastic pollution in small and medium-sized inshore bays in China, the main types, abundance, and spatial distribution characteristics of microplastics in the surface water and sediments in Haizhou Bay of Jiangsu province were studied by qualitative and quantitative methods. The results showed that the abundances of microplastics in the surface water and sediments of Haizhou Bay were (2.60±1.40) n·m-3 and (0.33±0.26) n·g-1, respectively. In the domestic offshore environment, the abundance of microplastics was at a low level in the surface water, but at a high level in the sediments in Haizhou Bay (0.33-545.00 n·m-3 and 0.07-2.58 n·g-1, respectively). The range of size distribution of microplastics in water and sediments was 0.08-13.48 mm and 0.04-14.74 mm, respectively. More than 60% of the microplastics in water and sediments were small particles of sizes less than 2.00 mm. The shape of microplastics in Haizhou Bay was mainly fibrous, accounting for 92%. The main colors were blue and black, accounting for 70%. The materials were mainly man-made fibers and PET, accounting for 79.4%. There was a significant correlation between the distribution of microplastics in surface water and suspended matter concentration (P<0.05). The distribution of microplastics in sediments was affected by many factors, and its distribution pattern between the distribution of microplastics in surface water and the distribution of particle size in sediments was quite different. Through analysis of the morphological characteristics and composition of microplastics, the results showed that the microplastics in Haizhou Bay mainly come from mariculture and coastal land sources.

Microplastic pollution in the riverine ecosystems has caught many attentions in the scientific literatures. However, little information is available about the abundance and distribution of microplastics of the rivers discharging to the Caspian Sea. The aim of this study was to assess the spatial and seasonal distribution of microplastics in the surface waters of thirteen rivers discharging to the southern Caspian Sea. Microplastics were found in all stations with uneven distributions. The average concentrations of microplastics in the stations during snowmelt and dry seasons were 1.406 ± 0.1380 microplastics/m3 and 0.4070 ± 0.01500 microplastics/m3, respectively. Positive gradients of the rivers microplastics concentration from upstream to downstream were found. White/transparent polyethylene (PE) particles with the shape of fragment/film and the length (L) of ≤ 1mm were the most common microplastics in the surface waters of the rivers discharging to the southern Caspian Sea. Also, the mean concentration of microplastics in spring snowmelt and runoff period was 3.45 times higher than in dry period. Factors such as sewage and household wastes; landfills; and recreational-tourism, fishing and agricultural activities along the rivers may contribute to microplastic contamination in downstream stations. Our data provide baseline information of microplastics in surface waters of rivers discharging to the southern Caspian Sea.

Increased demand for plastics has resulted in the generation of plastic waste, which poses a threat to the environment in general, and ultimately the marine environment. Estuaries and deltas are the main filters of marine ecosystem pollutants from inland sources. There have been limited studies on temporal variations in microplastic (MP) pollutants in tropical estuaries of Africa. In 2022, a twelve-month sampling survey study was conducted at Sabaki river estuary, in Kenya. A bucket was used to collect water samples, that were sieved through a 225μm sieve. A stereo microscope was used to identify microplastics and their polymer confirmed using FTIR spectroscopy. Data analysis on seasonal difference in abundance of microplastics in surface waters was performed using Minitab software at α ≤ 0.05. The results indicated that the April-June (A-J) long rains season had significantly (P ≤ 0.05) higher levels of MPs due to rainfall runoff, compared to other seasons, namely January –March (J-M), July-October (J-O) and November –December (N-D). The (J-M), (J-O) and (N-D) seasons had similar levels of MPs, which were lower compared to those observed during (A-J) long rains season by 44.3%, 54% and 25% respectively, compared to the highest concentration of 264 MPs m-3 observed during the A-J season. Fragments type of MPs were higher during the wet season, while fiber type of MPs dominated during the dry season. Film and form type of MPs were least abundant. Seasons significantly (P ≤ 0.05) influenced distribution of the different sizes of MPs. Small and medium sized category of MPs occurred and dominated during the dry season, while larger particles dominated during the wet season. Seven (7) differently colored MPs were observed during the study. White colored MPs were most prevalent (33%), followed by blue (23%), black (17%), brown (12%), yellow (5%), red (5%), and green (4%). Five types of plastic polymers were found in surface waters of river Sabaki estuary, namely polyethylene (PE), polypropylene (PP), polystyrene (PS), Polyethylene terephthalate (PET), and Acrylonitrile-butadiene-styrene (ABS).

Microplastics (MPs) are globally recognized as an emerging environmental threat, particularly in the aquatic environment. This study presents baseline data on the occurrence and distribution of MPs in sediments and surface water of major rivers in southwestern Nigeria. Microplastics were extracted by density separation and polymer identification using Fourier transformed infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR). The abundance of MPs in surface sediment and water samples across all locations ranged from 12.82 to 22.90 particle/kg dw and 6.71 to 17.12 particle/L during the dry season and 5.69 to 14.38 particle/kg dw and 12.41 to 22.73 particle/L during the wet season, respectively. On average, fiber constituted the highest percentage of MP in sediments (71%) and water (67%) while foam accounted for the lowest values of 0.6% and 1.7%, respectively. Polypropylene(PP) and polyethylene (PE) were the main MPs across all locations based on Fourier transform infrared spectroscopy (FTIR). MPs of size < 1mm were the most abundant (≥ 55%) on average in both water and sediments. The study identified run-off from human activities and industrial wastewater as potential sources of MP exposure based on positive matrix factorization. The study suggests assessing the impact of different land-use activities on MPs occurrence and distribution in addition to quantifying MPs in seafood as a way forward in food safety management systems for further studies. This study confirmed the occurrence and widespread distribution of MPs in surface water and sediments and provides a database on MP pollution in Nigeria.

An enhanced risk assessment framework for microplastics occurring in the Westerscheldt estuary

Microplastics are nowadays considered ubiquitous pollutants since they have been found widespread in all environmental compartments, particularly in aquatic systems. In urban water bodies, municipal wastewater discharges and overflows of combined storm and wastewater drains are the sources of microplastic pollution. The investigation was performed on the distribution of microplastics in the surface water of three urban lakes: West Lake, Yen So Lake, and Bay Mau Lake, from February 2020 to January 2021. Results show that microplastics were widely and unevenly distributed in all three lakes in Ha Noi and reached a high abundance on the site of West Lake, which is most intensively surrounded by population density, restaurants/bars, and aquaculture activities. Microplastic abundance was highest in February 2020 for all three urban lakes, with 154.92 items m-3 in Bay Mau, 589.46 items m-3 in West Lake, and 139.86 items m-3 in Yen So Lake. There was a decreasing trend in the following sampling times of July, October 2020, and January 2021 (range: Bay Mau: 16.02-59.04 items m-3; West Lake: 36.51-201.08 items m-3; Yen So: 14.07-67.27 items m-3). The dominant microplastics in urban lakes were fibers with a size of 1-3 mm, while microplastic fragments were 0.045-0.3 mm2. Analysis of the chemical composition of microplastics indicated dominance by rayon (13.5-58.5%) and polyethylene terephthalate (14.1-30.8%). This study is an essential reference for understanding the characteristics of the variation in microplastics in urban lakes to reduce local microplastic pollution effectively.

Influence of ongoing discharge from multiple wastewater treatment plants on microplastic patterns in small-scale receiving rivers

Microplastic pollution in surface water from east coastal areas of Guangdong, South China and preliminary study on microplastics biomonitoring using two marine fish

Microplastic (MP) pollution is now a global critical issue and has been the subject of considerable worry for multiple various types of habitats, notably in lagoons which are coastal areas connected to the ocean. MPs are of concern, particularly because floating MP in surface water can be ingested by a number of marine organisms. There are several lagoons along Southeast Asia's coastline, but Songkhla Lagoon is Thailand's only exit with a rich biodiversity. To date, there has been little research undertaken on MP in this lagoon, so there is a pressing need to learn more about the presence of MP in the lagoon's water. We investigate MPs in the surface water of Songkhla Lagoon, Thailand. Sampling took place at ten stations in the lagoon during the wet season in December 2022 and the dry season in February 2023. Samples were digested with hydrogen peroxide to remove organic matter followed by density separation using saturated sodium chloride. MPs were visually examined under a stereo microscope to describe and determine the shape, size, and color. Polymer type was identified using a micro Fourier transform infrared (FTIR) spectrometer. Moreover, the in-situ of water quality of the surface water was measured using a multi-parameter probe. A Mann-Whitney U test was performed to investigate the variations in MP levels and water quality parameters between the wet and dry seasons. Correlation analysis (Spearman rho) was used to determine the significance of correlations between MP and water quality (p < 0.05). MPs were detected at all ten of the sites sampled. The most abundant MPs were small size class (<500 µm, primarily consisting of fibers). Five types of polymers were seen in surface water, including polyethylene terephthalate, rayon, polypropylene, polyester, and poly (ethylene:propylene). Rayon and polyester were the dominant polymers. Additionally, the most dominant color of MPs in the wet and dry season was black and blue, respectively. The mean contents of MPs in the wet and dry season were 0.43 ± 0.18 and 0.34 ± 0.08 items/L, respectively. The Mann-Whitney U test suggested a significant difference between water quality in the wet and dry seasons (p < 0.05). Correlation analysis (Spearman rho) indicated a negative significant difference relationship between the MPs and the values of total dissolved solid (TDS) in the wet season (r = -0.821, p = <0.05), revealing that the large amounts of MPs may possibly be dispersed within surface water bodies with low TDS concentrations. Based on the overall findings, MP pollution in the surface water of the lagoon is not found to be influenced by the seasonal context. Rivers flowing into the lagoon, especially the U-Taphao River, may be a principal pathway contributing to increased MP pollution loading in the lagoon. The results can be used as baseline data to undertake further research work relevant to sources, fates, distribution, and impacts of MPs in other coastal lagoons.

Microplastic is an emerging global pollutant that have attracted a great deal of attention from researchers and the public. Guangdong Province has a large population and a relatively well-developed economy, but lacks a modern pollution control system. Guangdong has a long coastline with varying levels of pollution, and little research has been conducted on microplastics. Therefore, we investigated the level of microplastic pollution in coastal areas of Guangdong Province, and the abundance of microplastics in surface waters and sediments at 13 sampling sites. The abundance of microplastics in surface water and sediment samples ranged from 850 to 3500 items/L and 433.3 to 4166.3 items/kg, respectively. Fiber is the main type of microplastics in both surface water and sediment. The sampled microplastics were typically transparent. Raman results show that the surface water sample mainly includes rayon (38.2%), polyethylene terephthalate (16.4%), and ethylene/vinyl acetate copolymer (12.7%). This study used the pollution load index method to evaluate the pollution risk of microplastics along the coast of Guangdong, and provided the basis for the formulation of environmental policy.

Microplastic pollution in Taihu Lake: Spatial distribution from the lake inlet to the lake centre and vertical stratification in the water column

Microplastic pollution is an emerging threat to global freshwater ecological security. The emission and discharge of microplastic pollutants is highly associated with human activities and, therefore, cities are particularly at risk of microplastic pollution because they are a concentrated zone of plastic industry and use. Urban rivers may also be significant in transporting microplastic pollution from cities to other areas. Because of rapid urbanization, Chinese coastal cities are potentially at increasing risks of microplastic pollution from freshwater, atmospheric and terrestrial environments. Previous studies discovered that urban factors, including local population density, economic structures, and land-use patterns play decisive roles in microplastic pollution in China’s urban catchments. This study builds on past work by analysing the relationship between urban factors and freshwater microplastic pollution along an urban river channel in Ningbo, a megalopolis on the East Coast of China. The microplastic abundance in the Fenghua River, Ningbo, was compared to equivalent measures in other research. This study also considers local urban developments, revealing some of the core factors affecting urban microplastic pollution levels. This manuscript ultimately aims to find countermeasures for controlling China’s urban microplastic pollution. These measures will also provide some new perspectives for Chinese cities to deal with the spread and emission of other artificial contaminants in the future, so as to maintain the sustainable development in China, and extensively to other cities in the region.