Analele Ştiinţifice ale Universităţii „Alexandru Ioan Cuza”, Secţiunea Genetică şi Biologie Moleculară, TOM XI, 2010 DYNAMICS OF SOME WATER QUALITY INDICATORS ON ŞOMUZU MARE RIVER DURING 2008 CRISTINA MAXIM *,2 , DUMITRU COJOCARU 1 Keywords: Pollution, water quality indicators Abstract: The experimental data analyzed in this paper are part of a larger study concerning the evaluation of the degree of pollution of the waters in the superior basin of Siret River and refers to the dynamics of some chemical and biological parameters of Şomuzu Mare River, tributary to Siret River in Suceava County. INTRODUCTION One of the major issues of the contemporary society is the increasing pollution of the soil, waters, air and therefore of the aliments we consume. It is of utmost importance that the implementation of the ecological, pollution- free technologies is accompanied by a permanent monitoring of the surrounding environment in order to adopt the necessary measures to stop pollution. Since Suceava County has plenty of industrial firms, mining plants and animal farms presenting pollution potential, we have decided to present in the present paper some of the chemical and biochemical indicators by evaluating the chemical and biochemical Oxygen consumption (CBO 5 , CCO-Mn and respectively CCO-Cr) in the degree of pollution of the waters of a river tributary to Siret River in this county. MATERIALS AND METHODS In order to evaluate the dynamics of the pollution degree of the water in Şomuzu Mare River water samples have been collected from two different areas – the Vorniceni section, upstream, a place about 56 km up the flowing point; and the Dolheşti section, downstream, about 13 km from the flowing point - all along 2008, at a regular two months interval. There have been considered for the study the main quality indicators referring to the aerating character according to the present legislation: the concentration value of the dissolved oxygen which has been evaluated using the electrochemical method implying the use of a borehole, the biochemical oxygen consumption (CBO 5 ) after five days and the chemical oxygen consumption (using the potassium permanganate (CCO-Mn) method and the bichrome (CCO-Cr) method). RESULTS AND DISCUSSIONS In order to perform a correct interpretation of the values we have obtained after determining the concentration of the dissolved oxygen, the biochemical oxygen consumption after five days (CBO 5 ) and the chemical oxygen consumption (CCO-Mn and CCO-Cr), we have analyzed the results we have obtained by comparing them with the maximum limits admitted for the five water quality classes of the surface waters, according to the Regulation No. 161/2006 concerning the approval of the Normativ on the reference objectives of surface waters classification (table I) Table I: The maximum limits admitted for some of the surface water quality indicators according to the Regulation 161/2006 concerning the approval of the Normative on the reference objectives of surface waters classification Nr. crt. Quality indicator U/M Quality class I II III IV V 1 Dissolved oxygen mg O 2 /l 9 7 5 4 <4 2 BOC 5 mg O 2 /l 3 5 7 20 >20 3 CCO-Mn mg O 2 /l 5 10 20 50 >50 4 COD-Cr mg O 2 /l 10 25 50 125 >125 Given the fact that oxygen is a chemical element absolutely necessary to all aerobe organisms, including the aquatic ones, one of the water quality indicators measured is the concentration of the dissolved oxygen. 229