385 Analele Universităţii din Oradea, Fascicula Protecţia Mediului Vol. XVI, 2011 HEAVY METAL DINAMIC SURVEY IN THE WATER OF CRIŞUL NEGRU RIVER NW ROMANIA Fodor Alexandrina*, Petrehele Anda Ioana Graţiela, Stănăşel Oana Delia, Cărăban Alina Maria, Bereczki Eniko, Calapod Adriana Melania, Blidar Cristian Felix, Vancea-Petruş Adriana *University of Oradea, Faculty of Environmental Protection, 26 Gen. Magheru St., 410048 Oradea, Romania, e-mail: afodor@uoradea.ro Abstract The aim of the study is the survey of several heavy metals accumulation in the aquatic environment on along the Crişul Negru River course. The necessity of this study appeared due to the long tradition in mining activities in the area that could be a source of ecosystems contamination with heavy metals. The survey was undertaken during August 2008-July 2009 period. A total number of 140 water samples were taken. The analysed heavy metals were: the copper, cadmium, nickel, cobalt and zinc. These heavy metals were determinate using atomic absorption spectroscopy method. During the surveyed period it has been noticed a significant decrease in their concentrations among the sites, with the higher ones registered in the headwaters of the river, just in the vicinity of the mining area. The registered heavy metals concentrations were fluctuating as values in according to the season and the precipitations quantities. The heavy metals concentrations from the samples were also compare to samples taken in the same period from a control area considered not affected by mining pollution (Bulz on Crişul Repede River which flow in N-W Romania in the same County as Crişul Negru) revealing higher values. As a general classification of the water that flow through this sites due to Law no. 161/2006 reveal: third water quality class from the point of view of cadmium and cobalt. From the point of view of nickel, it can be noticed an increase of water quality from the first sampling site (third water quality class) on a downstream direction (for the rest of sampling sites, second class of water quality). From the point of view of copper and zinc, the river is still first class water quality. Key words: heavy metals, atomic absorption, water INTRODUCTION Water pollution is affecting the phytoplankton and macrophytes in different ways, according to the nature of the contaminant. For example the chromates and copper salts are toxic to algae. Fish and plankton can die from all types of pollution but most fatal one is caused by lack of oxygen dissolved in water and toxic waste. Serious problems also raise the pollution of water with heavy metals, especially mercury, which reach a large degree in accumulation. The whole ecological consequences resulting from biosphere pollution with heavy metals is a warning sign to end the irresponsible behaviour of industrial activities on water quality. Heavy metals are elements with atomic mass between 63.546 and 200 m.a.u. Living organism require very small amounts (trace) of heavy metals (Co, Cu, Fe, Mn, Mo, Sr, Zn) whish are called essential heavy metals. The remaining heavy metals found in water are toxic for living animal and