Biofouling protection for marine environmental sensors

These days, many marine autonomous environment monitoring networks are set up in the world. These systems take advantage of existing superstructures such as offshore platforms, lightships, piers, breakwaters or are placed on specially designed buoys or underwater oceanographic structures. These systems commonly use various sensors to measure parameters such as dissolved oxygen, turbidity, conductivity, pH or fluorescence. Emphasis has to be put on the long term quality of measurements, yet sensors may face very short-term biofouling effects. Biofouling can disrupt the quality of the measurements, sometimes in less than a week. <br><br> Many techniques to prevent biofouling on instrumentation are listed and studied by researchers and manufacturers. Very few of them are implemented on instruments and of those very few have been tested in situ on oceanographic sensors for deployment of at least one or two months. <br><br> This paper presents a review of techniques used to protect against biofouling of in situ sensors and gives a short list and description of promising techniques

Capteurs bio-chimiques Groupe I : capteurs chimiques a fibres optiques

Etude recouvrant les subventions 91-B-0270 a 91-B-0279 inclusesAvailable at INIST (FR), Document Supply Service, under shelf-number : AR 15533 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Effects of a sewage plume on the biology, optical characteristics, and particle size distributions of coastal waters

The effect of a sewage plume on the biology, optical characteristics, and particle size distributions of coastal waters was evaluated around the Sand Island, Hawaii, outfall diffuser. In situ physical and biooptical data and Niskin bottle samples were collected during a 1-week cruise from September 25 to October 1, 1994. One or two layers affected by sewage could be distinguished in the water column: recently discharged (''new'') sewage plume waters and ''old'' plume waters. In conditions characterized by high Froude number the distribution of chlorophyll fluorescence in new plume waters was the same as for ambient waters, while for low Froude number, chlorophyll fluorescence increased within the plume, demonstrating the importance of physical forcing on effluent and phytoplankton interactions. New plume waters were associated with at least 2.7-fold increases in particle load, high concentrations of particles larger than 70 mu m, increases in ammonium, phosphate, and silicate, and high levels of heterotrophic bacteria and Prochlorococcus compared to surrounding waters. Both new and old plume layers, but not phytoplankton layers, showed distinct increases in fluorescence for the excitation/emission (Ex/Em) wavelength pair Ex/Em = 228/340 in mm, interpreted as particulate tryptophan-like fluorescence. Such fluorescence may be useful as a new in situ real-time indicator of waters affected by effluent discharges