Multiparametric classification of trophic conditions. The OECD methodology extended: combined probabilities and uncertainties - application to the north Adriatic Sea

A newa pproacht o trophic classiticationo f water bodiesb, asedo n combiningt he exactp robabilitiesf rom the OECD (Organizationf or EconomicC ooperationa nd Development)lo gnormalf requencyd istributionso f chlorophyll, nitrogen, a ndp hosphorusc oncentrationsa ndS ecchdi epths,i sp resentedu, singa sampled ata setf rom monitoringa ctivities carried out in the North Adriatic Sea in the summer of 1992. This probabilistic approach is shown to be effective in solvingu ncertaino r even contradictory classificationws hichm ay often arisef rom membershipr obabilities,b asedo n singles amplev ariables,a si n the presentO ECD system.S uch an extensiont o multiparametrics amples pacei s open to possiblem odiications of trophic variables,a nd allowsc omparisonsa mongs amplews ith inhomogeneouosr even unmatchingt ypes of measurementCs.l assificationu ncertaintiesc, ausedb y the uncouplingo f trophic variables,a re shownt o be relatedt o environmentadl isturbancesg ivenb y dischargesin, flowsa nd turbulent diffusion. Their role in trophic classiticationp roceduresa, nd environmentailm portancea nd meaningis s tresseidn relation to the applicability of the extended OECD methodology to non-steady state systems.