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

Oiste Ana Maria, Breaban Iuliana Gabriela, University Al. I. Cuza Iasi, Romania

Abstract

The tributaries water quality influences the physico-chemical of the Bahlui river due to built-crossing areas with different functions, this being emphasized by parameters variability. 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, indicating a seasonal variation.
Field observations were conducted to study the main rivers and to establish sampling points, then followed river sampling of Bahlui river and its tributaries (Bahlui – 42 samples, on the left: Nicolina - 15 samples, and on the right: Rediu - 7 samples, Cacaina - 7 samples, Ciric - 5 samples), and seasonal reference sample was collected in three different seasons: in December, April, June and October, 2010-2011.
Physical indicators were analyzed: pH, electrical conductivity and 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). The results are validate and processed using statistical methods like multivariate analyse
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.
Bahlui River and its tributaries 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 (chemistry and biochemistry). Inorganic pollutants from human activities, such as Nicolina river crossing a heavily polluted former industrial area - CUG Iasi, inorganic pollutants such as heavy metals with remaining action, influencing water quality.
The study showed the synergic action of physico-chemical characteristics of organic and inorganic pollutants regime over the succession of seasons.