A study of surface water quality in Macedonia, Greece: Speciation of nitrogen and phosphorus

A 2-yr (1997-1998) survey aiming at the establishment of national data base s concerning the quality of surface waters has been conducted in the major river systems of Macedonia, N. Greece. This paper presents the physicochemi cal parameters (pH, conductivity, total suspended solids, temperature and D O), the organic pollution parameters (BOD5, COD) and the major N and P spec ies (NO3-, NO2-, NH4+, organic N, orthophosphates and total P) determined a t 25 sampling sites located on main rivers, tributaries, streams and ditche s that drain the major rural, agricultural, urban and industrial areas of N . Greece. Use of multivariate statistics is also made to identify the princ ipal factors which influence the chemistry of the water in individual river systems. The eutrophication status of the examined systems was evaluated b y means of N/P ratios. Mean N/P ratios showed large variations among sampli ng sites ranging from potential N- to P-limitation conditions. N/P ratios a t particular sampling sites showed also great temporal variability thus sug gesting temporary states of N- or P- limitation. Most frequently, highest r atio values were observed during winter and early spring. Comparisons are m ade between data from this study region and literature on rivers elsewhere.