Measuring the health of the sea
Last summer Donostia City Council installed a special buoy in the city's Concha Bay. The apparatus carried out analyses of the water quality in order to verify its suitability for bathing. This buoy was anchored at the bottom of the sea, halfway between the Santa Clara islet and the Concha and Ondarreta beaches. Now, a newly incorporated sensor that analyses the bacteriology of the water extends the analytical capacity of the buoy. This buoy has been designed by the company URSAT in Langraiz, in collaboration with AZTI and INASMET technological centres. The buoy is a veritable floating laboratory that takes in water, measures its physical and chemical properties such as turbidity, temperature, acidity and the amount of dissolved salt and oxygen, amongst other parameters. It carries out the analyses and sends the results by radio to a control centre in the Donostia aquarium. Moreover, it has a great variety of communications possibilities such as data transmission via GSM or by satellite. In this way, the water quality can be controlled continually in real time from the nearby Aquarium to such an extent that any change can be detected immediately. In the future, instead of the buoy in Donostia City Bay having batteries, it will have solar panels which will mean the buoy will be an energetically autonomous floating laboratory. The buoy also contains a sensor for hydrocarbons, which is continually floating in the water. This sensor emits electromagnetic waves and, through electromagnetic differences, is able to detect if a film of hydrocarbons exists or not. This information is transmitted to a controler that warns us of the danger and raises the alarm at the control centre. The buoy also undertakes other analyses. As a consequence of human presence on the coast, organic compounds are found in the sea and these can provoke a huge growth in algae. The new buoy will be able to measure the quantity of nutrients and algae in the sea. Moreover, it will be able to make bacteriological measurements. Up to now, in order to measure the water quality, a boat left port approximately every fortnight in order to collect a sample of water, which was then taken to the laboratory for analysis. Now, the buoy can detect bacteria detrimental to human health such as, for example, those usually found in human excrement. The probe analysing this parameter is suspended below the buoy, given that the sun's ultraviolet rays can kill the bacteria at the surface. Thus, these bacteria are more abundant at somewhat greater depths, precisely where the probe takes the sample. With all this data, the buoy will transmit an on-going profile by satellite of the state of health of the water.
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