Microplastics in the River Ganga and its fishes: Study of a Himalayan River.

The River Ganga has been explored for microplastics (MPs) majorly in the lower or middle course, while the upper course from where the river starts its journey remains untouched. This study investigates the occurrence and distribution of MPs in the river environment (water and sediment) and common fishes inhabiting the upper stretch of River Ganga in the Uttarakhand state of India. A volume-reduce method by using sieve filtration was used to take water and sediment samples from the study area while fish samples were collected using net method. The samples underwent alkali digestion, microscopic examination, and chemical analysis using Fourier Transformed Infrared Spectroscopy (FTIR). An average of 118.5 ± 49.65 particles per 1000 L and 131.5 ± 53.60 particles/kg dry weight were found in water and sediment respectively. While in the fishes, Tor tor, Schizothorax richardsonii, Labeo dero and Gara gotyla gotyla MPs were 53.13 ± 63.77, 36.33 ± 22.34, 15.42 ± 9.33 and 12.63 ± 5.93 particles/individual respectively. A positive correlation was observed between the number of MPs in fish and their body length, weight, and gut weight, while no correlation was found between feeding habit and MP accumulation. The majority of MPs detected were fibers ranging from 100 µm to 1 mm in size. Polymer types varied among water, sediment, and fish samples, with polyethylene (PE) predominant in water, polypropylene (PP) dominant in sediment, and polyethylene terephthalate (PET) and polystyrene (PS) most abundant in fish samples.

Microplastics in fishes from the Northern Bay of Bengal.

Microplastics were determined in pink Bombay-duck (Harpadon nehereus), white Bombay-duck (H. translucens) and gold-stripe sardine (Sardinella gibbosa) collected from the Northern Bay of Bengal at Bangladesh. Gastrointestinal tracts of fishes (n = 25 per species) were examined for microplastics following alkali digestion protocol, microscopic observations and chemical analysis by micro-Fourier Transformed Infrared Spectroscope (µ-FTIR). A total of 443 microplastic items were found in the intestines of H. nehereus, H. translucens and S. gibbosa, averaging in the range of 3.20-8.72 items per species. Among various shapes, colours and types of microplastics, irregular (37-43%), white/transparent (26-68%) and fiber (50-55%) were dominant. The size fraction of microplastics ranging between 1 µm and 5 mm was 68-84 items/kg biomass, and µ-FTIR analysis identified 13 particles of polyethylene terephthalate and 66 particles of polyamide. The study findings raised concern that microplastics in marine fish could be a threat to public health via the food chain.