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Results and discussionDuring 2009 (spring-summer period) the decreasingtendency of the content of phosphorus forms, especiallyfor P7, P10 and P11, was recorded along river Dniester(Fig. 2). The maximal amounts of these forms wereregistered in lake Dubasari (Oxentia and Malovata sites).Nevertheless, for some forms (orthophosphates P6 andorganic-phosphorus P8) higher contents were registeredfor Vadul-lui-Voda site.Seasonally, the decreasing tendency of the amountsof most phosphorus forms (dissolved condensed P7 andorganic P8 forms, also particulate P10 and P11 forms)was registered from spring towards summer. On thewhole, seasonal dynamics of most phosphorus formsregistered during 2009 agree well with ones establishedduring 2004 [6].Percentage distribution of phosphorus forms inparticulate materials is presented in Fig. 3. Generally,the amounts of organic fraction (P12) registered during2009 agree well with ones established during 2004.Much more changes were registered for inorganicforms, orthophosphate P10 and condensed forms P11(polyphosphates and pyrophosphates).Concerning phosphorus forms in bottom sediments(Fig. 4), spatial dynamics was more evidence for totalphosphorus (form P13), being registered the decreasingtendency of the content along river Dniester. The maximalamounts were registered in lake Dubasari (Oxentia andMalovata sites). Seasonally, the increasing tendency ofthe amounts of total phosphorus (form P13) was registeredfrom spring towards summer. On the whole, spatial andseasonal dynamics of total phosphorus registered during2009 agree well with ones established during 2004 [6].Percentage distribution of organic and inorganicphosphorus in particulate materials and bottom sedimentswas similar during the summer of 2004 and 2009 years(Fig. 5).In large quantities phosphorus compounds havefertilizing effect for aquatic ecosystem affecting itseutrophication level. According to Directives of EuropeanCommunity [7-9], the eutrophication level is recommendedto be given on the basis of quality grade thresholds forFig. 2. Spatial and seasonal dynamics of phosphorus forms for river Dniester during 2009.Dissolved forms P6, P7, P8 –orthophosphate, condensed forms (poly– and pyrophosphates) and organic-phosphorus, respectively.Phosphorus forms in particulate forms P10, P11, P12 – orthophosphates, condensed forms and organic-phosphorus, respectively.Fig. 3. Percentage distribution of phosphorus forms in particulate materials (summer, 2004 and 2009 years).P10, P11, P12 – orthophosphates, condensed forms and organic-phosphorus in particulate materials, respectively.— 193 —