INCREASED MORTALITY OF FISH DUE TO CHANGING 9 AL-CHEMISTRY OF MIXING ZONES BETWEEN LIMED STREAMS AND ACIDIC TRIBUTARIES

• Main Authors: A. B. S. Polt~o, E. Lydersen, B. O. Rosseland, E Kroglund, B. Salbu, R. D. Vogt, A. Kvellestad
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1993
• Subjects: Atlantic salmon; Salmo salar
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.476.3414; http://folk.uio.no/rvogt/CV/Co-author/Poleo et al.pdf

Abstract. The present study is mainly focusing on mortality variations of fish due to changing A1-chemistry of mixing zones. An artificial mixing zone was made by pumping water from a limed stream and an acidic tributary into a mixing channel. Atlantic salmon (Salmo salar L.) parr were exposed to the mixed water, limed stream water, and acidic tributary water. Mortality, blood haematocrit and plasma C1--concentration were recorded. Neither mortality, nor changes in haematocrit and plasma C1- were observed when fish were exposed to limed water, while in both acidic and mixed water, mortalities and loss of plasma CI- were observed. The highest mortality rates were found within the initial part (0 to 20 s) of the mixing zone. Blood haematocrit increased only in fish exposed to acidic tributary water. Our results hows that changes in Al-chemistry and subsequent Al-polymerization occur when acidic tributary water is mixed with limed stream water. We have also demonstrated that the toxicity which can arise in mixing zones are greater than in the original acidic water before mixing. The variations in mortality observed are associated with the quality and quantity of Al-polymerization as well as ageing of the polymers. 1.