A computer-based system for the acquisition and display of continuous vertical profiles of temperature, salinity, fluorescence and nutrients

Abstract

A vertical profiling system was developed to continuously measure and simultaneously log temperature, salinity, depth, fluorescence and selected nutrient concentrations (NO 3 −, NH 4 +, SiO 4 4− and PO 4 3−) in the euphotic zone in coastal waters. A hose was attached to a CTD sensor and lowered through the water at 1 m min −1. Water was pumped to the ship's deck with a diaphragm pump, and passed through a fluorometer and Technicon AutoAnalyzer ® to measure fluorescence and selected nutrients, respectively. A 25 m vertical profile takes about 30 min to complete. These instruments were connected to an analog-to-digital converter, and the data were stored and plotted using an IBM personal computer to simultaneously display real-time vertical profiles of temperature, salinity, fluorescence and several nutrient concentrations. This instrument package is invaluable because it provides real-time data that are essential for choosing discrete sampling depths, and for obtaining a time series of the vertical structure of the euphotic zone of dynamic coastal waters or lakes.