Invisible face of boron pollution in fluvial ecosystem: the level in the tissues of sentinel and nectonic organisms.

Turkey is the largest producer of borate products in the world. Among four largest boron mines in Turkey two of them are located in basins of Orhaneli and Emet Streams. In this study, boron levels in abiotic (water-sediment) and some biotic elements (sentinel organisms; Asellus aquaticus, Gammarus pulex, Chironomus tentans, Limnodrilus hoffmeisteri and nektonic organism; Squalius cii) of Orhaneli and Emet Streams were investigated and their ranks among the food chain were demonstrated. Since Orhaneli and Emet Streams confluence to form Mustafakemalpaşa Brook which feeds Uluabat Lake which is one of the most important Ramsar fields of the world, Boron levels in those two streams have importance in terms of both continuances of aquatic systems. Present study results have shown that boron levels in water of both streams are much higher (vary between 8.64 and 16.73 mg L(-1)) than not only Turkish Standard but also limits determined by WHO, US EPA, and NAS. Boron levels determined in sediments of two streams vary between 18.05 and 36.7 mg kg(-1). The highest boron level in the biotic elements was determined in liver of Squalius cii (34.64 mg kg(-1)), it is followed by Limnodrilus hoffmeisteri (2.84 mg kg(-1)), Chironomus tentans (2.11 mg kg(-1)), and Gammarus pulex (1.98 mg kg(-1)).