ALBERT

Description: Nitrite and nitrate as nitrogen (NO3+NO2), ammonium as nitrogen (NH4+), ortho-phosphate as phosphorus (o-PO4) and silica (SiO2) analyzes were measured by a QuAAtro39 Continuous Segmented Flow Analyzer consisting of an autosampler, a peristaltic pump, a chemistry manifold, a detector and data acquisition software. This protocol is in accordance with standard methods for the examination of water and wastewater. Dissolved oxygen (DO) was measured by using the Winkler method, in which a divalent manganese solution and strong alkali are added sequentially to the samples. Thus, dissolved oxygen rapidly oxidizes an equivalent amount of divalent manganese to basic hydroxides of higher valency states. With the presence of iodide ions in acidic conditions, the oxidized manganese reverts to its divalent state, and meanwhile, the iodine equivalent to the dissolved oxygen in the sample is released. This released iodine is titrated with a standardized thiosulfate solution and the dissolved oxygen value in the sample is calculated by potentiometric measurement using Metrohm 905 Titrando automatic titrator system. Dissolved oxygen samples are taken and analyzed in duplicate. The relative percent difference (RPD) of duplicates did not exceed 4.3% (Average is 0.62%). All results were also compared with the CTD dissolved oxygen data. pH measurements of sea waters were measured in lab by Mettler Toledo SevenMulti pH meter. The pH meter was calibrated every two days with the calibration standards at the values of 7.00 and 9.21. During the measurements, the pH values were recorded together with the current sample temperature values.