engleski

Impact of municipal and industrial wastewaters on microplastic exposure and toxic effects of karst river water

Although wastewater-impacted rivers represent an important source of plastic pollution, most research on microplastics (MPs) in aquatic ecosystems has been conducted in the ocean. Accordingly, there is a lack of data on MP exposure and toxic effects on freshwater organisms, especially in the environmental conditions. The present study investigated MP exposure, water quality, and toxic effects on organisms in the Krka River in Croatia, karst watercourse which is influenced by municipal and industrial wastewaters. Sampling of water and native fish, brown trout (Salmo trutta Linnaeus, 1758), was conducted in spring 2021 at three sites: Krka River source (a reference site, KRS), municipal wastewater outlet (KRK), and industrial wastewaters from a screw factory (IWW). Water analysis included detection of MP, measurement of water quality parameters and toxicity tests with microalgae (Pseudokirchneriella subcapitata (Korshikov) F. Hindák, 1990) and crustaceans (Daphnia magna Straus, 1820). Ingestion of MP by fish was confirmed by acid digestion and examination of their gut contents. MP was found in almost all trout individuals and water samples, including the uncontaminated reference site. According to the Lowest Ineffective Dilution values (LIDA after 72 h exposure for algae and LIDD after 48 h exposure for Daphnia), both organisms indicated good water quality at KRS (LID = 1), some toxic effect at KRK (LIDA = 2, LIDD = 2) and high toxicity of IWW (LIDA = 32, LIDD = 18). The same trend was confirmed by the water quality parameters, which were much higher at IWW than at other sites, and some of them (chemical oxygen demand (COD), nitrate, total nitrogen, total phosphorus, mineral oils, total organic carbon) exceeded the limits defined by the Regulation on limit values for wastewater emissions in Croatia. Anthropogenic influence was also confirmed near municipal outlet in KRK, reflected as higher turbidity, COD, total nitrogen and total phosphorus compared to KRS. Our results indicated exposure to MPs and negative influence of wastewaters on river water quality and freshwater organisms of different trophic levels. These complex interactions need to be further investigated to preserve the Krka River and other sensitive karst ecosystems.

bioassay ; green algae ; water fleas ; Dinaric karst region

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