RESUMEN
The degradation of surfaces and its possible dependence on shape, size, and elemental composition of plastic particles were subjected. The surfaces of 146 microplastics were classified from smooth to fully eroded (%) by SEM/EDS. Structural elements and various additives were found on microplastics depending on their shapes. The surface of plastic items > 100 µm in length showed a relatively more eroded area than smaller ones, regardless of their shapes. Depending on shape, the percentage of surface erosion of irregularly shaped fragments < 100 µm was significantly enhanced compared to microbeads of the same size. These results may provide insights into assessing potential risks posed by microplastics and improve our understanding of the role of these parameters concerning possible adverse health effects on the environment.
RESUMEN
The occurrence of microplastics (MPs) in the digestive tract of commercial Kutum fish, Rutilus frisii kutum was investigated. Fish samples, ranging from 33 to 48.5 cm fork length which sold for human consumption, were collected from local fish markets in Bandar-e Torkaman (the south-eastern of Caspian Sea) on November 2017, and March 2018. The MPs were characterized using optical microscopy, NR staining, and SEM-EDS for number, shape, color, surface morphology, and elemental composition. On average, 11.4 MP items per fish (0.015 items per 1 g fish wet weight) were found in Kutum's stomach at an individual detection rate of 80%. Around 66% of all identified MP items were < 500 µm, and 53% possessed light colors. Morphological researches indicated that fish ingested the degradation fragments from larger plastic pieces, fibers, and manufactured microbeads. Microfibers are the most dominant items accounting for over 75% of all MPs. The SEM images indicated the various degrees of erosions upon environmental exposure. Some MPs had surface cracks, broken margins, scaly appearances, and obvious pores. Considering the commercial importance which the Kutum plays for Iran's fishery, the potential effect of MPs on the trophic food web, particularly for human consumption and health, should be urgently investigated.
Asunto(s)
Cyprinidae , Contaminantes Químicos del Agua , Animales , Mar Caspio , Monitoreo del Ambiente , Humanos , Irán , Microplásticos , Plásticos , Contaminantes Químicos del Agua/análisisRESUMEN
The localization of Na(+) , K(+) -ATPase (NKA) and the ultrastructural features of kidney were examined in larvae of the Persian sturgeon Acipenser persicus (L 31-41 mm total length and 182·3-417·3 mg). Investigations were conducted through light and electron microscopy and through immunofluorescence for NKA detection. The kidney nephrons consisted of a large glomerulus and tubules (neck, proximal, distal and collecting), which connected to the ureters. Posteriorly, ureters extended and joined together into a thin-walled ureter terminal sac. Ultrastructurally, the glomerular cells (podocytes) possessed distinctive pedicels that extended to the basal membrane. The proximal tubule (PT) showed two different cells. The cells lining the anterior part of PT possessed apical tall microvilli (c. 2·7 µm), a sub-apical tubular system, a basal nucleus and dense granules. Posteriorly in the cells, the sub-apical tubular system and granules were absent and round mitochondria associated with basolateral infoldings were found; the apical microvilli were reduced. Distal and collecting tubular cells showed the typical features of osmoregulatory cells, i.e. well-developed basolateral infoldings associated with numerous mitochondria. No immunofluorescence of NKA was detected in the glomeruli. A weak immunostaining was observed at the basolateral side of the cells lining the neck and PT. A strong immunostaining of NKA was observed in the entire cells of the distal tubules, collecting tubules and in some isolated cells of the ureters. In all immunostained cells, the basolateral region showed a much higher fluorescence and nuclei were immunonegative. In conclusion, the epithelial cells of kidney tubules had morphological and enzymatic features of ionocytes, particularly in the distal and collecting tubules. Thus, the kidney of A. persicus larvae possesses active ion exchange capabilities and, beside its implication in excretion, participates in osmoregulation.