ORGANIC AND INORGANIC CONTAMINANTS IN THE BAHLUI RIVER IN
THE BUILT-UP AREA OF IASI CITY

Ana Maria Oişte, Iuliana Gabriela Breabăn

„Al.I.Cuza”University, Faculty of Geography and Geology, Iaşi, Romania

Abstract

The physico-chemical composition of Bahlui river water depends on number of factors such as: geochemical nature of river bed, rainfalls, as well as anthropogenic activities. This study highlights the seasonal dynamics of water quality due to the presence of organic and inorganic contaminants in the urban sector of Bahlui river. The main tributaries of the Bahlui river, which cross through the Iasi city, are from the north: Rediu, Cacaina, Ciric, and from south: Nicolina, the last one being the longest tributaries the Bahlui river receives. There was taken samples during different seasons: summer, winter, autumn and spring, between December 2010 to October 2011, indicating a seasonal variation. The most important analysed physico-chemical indicators were: pH, electrical conductivity, turbidity, the chemical regime of oxygen (DO, chemical oxygen demand (COD) and biological oxygen demand (BOD), indicators of the mineralization degree (chlorides, sulphates, phosphates), hardness, alkalinity, organic and inorganic contaminants (heavy metals, nitrogen compounds - nitrate, ammonium). Laboratory analysis revealed that rivers entering the town with some original features, which then decays, reaching the river collector (Bahlui river) with different characteristics influencing quality. Concentration of contaminants in surface waters can vary depending on runoff caused by rainfall. The water from Bahlui River are affected by multiple pollution sources originating from industrial, residential and agricultural, located in densely populated areas. High turbidity levels are associated with the presence of a large number of microorganisms, reflected by the consumption of oxygen. Inorganic pollutants from human activities, such as former steel industry - CUG Iasi, affect the crossing river quality heavy metals being characterised by remaining action. For evaluation of both chemical variation as well as seasonal effect on the variables, box and whisker plots were performed. Connections among different sampling points were put into evidence by dendrogram, cluster analysis clearly grouped the monitoring sites in five regions with different pollution levels. The statistical evaluation of data yielded very useful information concerning water quality being a very useful tool for a better water resources management.

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