Performance of the MiniFluo-UV sensor for monitoring ocean and coastal environments

Understanding the biogeochemical functioning of the ocean requires high frequency recordings of DOM (Dissolved Organic Matter) descriptors that traditional tools such chromatography cannot provide. For 10 years, the technological developments of fluorescence sensor try to cover this need. Indeed, optical properties allow to properly characterizing DOM and can be acquired at high frequency. In this context, our laboratory developed the MiniFluo-UV sensor, a prototype of miniaturized submersible fluorometers for the detection of aromatic compounds that fluoresce in the UV domain. The qualification of the sensor consisted of measurement of drift, linearity, repeatability, sensitivity to light, temperature and pressure, and detection limits of quantification of phenanthrene and tryptophan in standard solution. Validation was made by comparing measurements of phenanthrene concentrations in crude oil WSF by means of the MiniFluo and different fluorimeters. In this presentation, we show results of deployments of this MiniFluo-UV sensor in two distinct areas, 1) the North Western Mediterranean during the continuous monitoring of the surface water layer in the Gulf of Lion (DEWEX cruise, winter and spring 2013) and 2) the coastal marine area of Marseille bay heavily impacted by urban activities. The pattern of raw counts enabled to distinguish interesting distributions of DOM in relation to hydrological features and spring biological production in the Gulf of Lion. It also revealed accumulations of contaminants in marine areas under anthropic pressure.