Microplastics are plastics that measure less than 5 mm in diameter. They enter the marine environment as primary sources directly from industrial uses, as well as secondary sources resulting from the degradation of large plastic debris. To improve the knowledge of microplastic pollution in China, we investigated samples from 53 estuarine sediment locations collected with a box corer within the Changjiang Estuary. Microplastics (<5 mm) were extracted from sediments by density separation, after which they were observed under a microscope and categorized according to shape, color and size. Identification was carried out using Micro-Fourier-Transform Infrared Spectroscopy (μ-FT-IR).The abundance of microplastics in the Changjiang Estuary was mapped. The mean concentration was 121 ± 9 items per kg of dry weight, varying from 20 to 340 items per kg of dry weight. It was found that the concentration of microplastics was the highest on the southeast coast of Shanghai. The distribution pattern of microplastics may be affected by the Changjiang diluted water in summer. All of the microplastics collected were categorized according to shape, color and size. Among which fiber (93%), transparent (42%) and small microplastics (<1 mm) (58%) were the most abundant types. No clear correlation between microplastics and the finer sediment fraction was found. Rayon, polyester, and acrylic were the most abundant types of microplastics identified, indicating that the main source of microplastics in the Changjiang Estuary was from washing clothes (the primary source). It is possible to compare microplastic abundance in this study with the results of other related studies using the same quantification method. The identification of microplastics raises the awareness of microplastic pollution from drainage systems. The prevalence of microplastic pollution calls for monitoring microplastics at a national scale on a regular basis.

Washing clothes made from synthetic materials has been identified as a potentially important source of microscopic fibres to the environment. This study examined the release of fibres from polyester, polyester-cotton blend and acrylic fabrics. These fabrics were laundered under various conditions of temperature, detergent and conditioner. Fibres from waste effluent were examined and the mass, abundance and fibre size compared between treatments. Average fibre size ranged between 11.9 and 17.7μm in diameter, and 5.0 and 7.8mm in length. Polyester-cotton fabric consistently shed significantly fewer fibres than either polyester or acrylic. However, fibre release varied according to wash treatment with various complex interactions. We estimate over 700,000 fibres could be released from an average 6kg wash load of acrylic fabric. As fibres have been reported in effluent from sewage treatment plants, our data indicates fibres released by washing of clothing could be an important source of microplastics to aquatic habitats.

In two previous papers, the authors have shown that benzothiazole, benzotriazole, quinoline, and several of their derivatives are widespread in clothing textile articles. A number of these compounds exhibit allergenic and irritating properties and, due to their octanol–water partition coefficient, are prone to be absorbed by the skin. Moreover, they are slightly soluble in water, which could make washing of clothes a route of emission into the environment. In the present study, the washout effect of benzothiazole, benzotriazole, quinoline, and some of their derivatives has been investigated. Twenty-seven textile samples were analyzed before, as well as after five and ten times of washing. The most abundant analyte was found to be benzothiazole, which was detected in 85 % of the samples with an average concentration of 0.53 μg/g (median 0.44 μg/g), followed by quinoline, detected in 81 % of the samples with an average concentration of 2.42 μg/g (median 0.21 μg/g). The average decrease in concentration for benzothiazoles was 50 % after ten times washing, while it was around 20 % for quinolines. The average emission to household wastewater of benzothiazoles and quinolines during one washing (5 kg of clothes made from polyester materials) was calculated to 0.5 and 0.24 g, respectively. These results strongly indicate that laundering of clothing textiles can be an important source of release of these compounds to household wastewater and in the end to aquatic environments. It also demonstrates a potential source of human exposure to these chemicals since considerable amounts of the compounds remain in the clothes even after ten times of washing.