Colorimetric Chemical Differentiation and Detection of Phosphorus in Eutrophic and High Particulate Waters: Advantages of a New Monitoring Approach

Phosphorus (P) is a key factor forcing eutrophication in limnic and marine systems, and all monitoring programs for water quality accordingly include P determinations. However, traditional monitoring does not allow an analysis of the different components involved in the P cycle taking place in the water column. Nonetheless, the implementation of measures addressing eutrophication requires a full understanding of the processes involved in the transformation and transport of P, in all its chemical forms. In this study, the P categories present in a river and its estuary in northern Germany, which discharge into the Baltic Sea, were characterized. Using the molybdenum blue method we found that the classification of P into the traditional fractions (DIP, DOP, POP) applied in the ocean cannot be applied to turbid waters such as rivers because interferences between the fractions seems to occur. Therefore a new nomenclature has been introduced. In addition to total phosphorus (TP) and dissolved molybdate-reactive phosphorus (DRP; previously referred to as inorganic phosphorus), dissolved non-molybdate-reactive phosphorus (DNP), particulate molybdatereactive phosphorus (PRP), and particulate non-molybdate-reactive phosphorus (PNP) were distinguished. The high spatial and temporal variations in the proportions of these forms with respect to the TP concentration well-demonstrate the complexity of the P cycle and the involved P fractions and emphasize the need for expanded monitoring approach. The potential of eutrophication could be underestimated if not all P categories were considered. With the new operational nomenclature the common and standardized molybdenum blue reaction could be used to implement the analysis of various P components into regular monitoring programs

Phosphor Dynamik in den Sedimenten der Darß-Zingster Boddenkette, einem eutrophierten Ästuar der südlichen Ostsee

The role of the sediment in phosphorus cycling in the Darß-Zingst Bodden Chain (DZBC) was analysed on two stations in 0.5 m and 2 m water depth in the Grabow representing the both main sediment types of the DZBC. Phosphorus did not accumulate in the muddy sediments of deeper Bodden areas (<1 m). Because in the DZBC the sediment surface is well oxygenated during the year, the adsorption potential of the oxidized sediment surface surmounts the release potential of deeper anoxic sediment layers. Therefore, the sediments of the DZBC rather act as phosphorus sink than as source