MONITORING & ALERT NETWORK in response to the health problems of Sargasso algae
Martinique has been facing a major health problem in recent years. Indeed, since 2011, the unprecedented phenomenon of massive stranding of Sargasso algae has affected the Atlantic and southern coasts of Martinique. This phenomenon is the origin of a smelling gas emanating from the putrefaction of algae, among these gases hydrogen sulfide (H2S) and ammonia (NH3). Beyond the olfactory discomfort, these gases have health effects, which the severity increases with the duration and level of exposure.
In front of the magnitude of this cyclical phenomenon, the regional institutions have decided to set up a network to monitor these gases. This network, initiated by the Regional Health Agency, accompanied by the Observatory for monitoring air quality in Martinique, Madininair, has the objective to follow the exposure of populations, on an important and diversified scale, allowing both a global vision and the detection of specific situations.
The levels of concentration measured and the health risks of exposure of local residents will be an essential element, in particular by orienting and prioritizing algae removal areas. This environmental network for monitoring the emanations of decomposing algae combines sensors to measure H2S and NH3 concentrations. Adaptable and responsive, its main objective is to provide decision support for local institutions by transmitting updated data on a daily basis throughout Martinique’s impacted coastline.
- Monitoring: real-time and continuous monitoring of concentrations of hydrogen sulfide (H2S) and ammonia (NH3).
- Alert: If the first health threshold in H2S is exceeded, information is transmitted to the institutions for taking action as soon as possible.
- Daily Information: daily Transmission of processed and formatted data to the partners and the public of the health risk, via a daily report.
- Decision Support: Adaptability of the network to the needs, exploitation of transmitted data, prioritization of pickup sites, health and behavioral recommendations
MATERIALS AND METHODS USED
To address this issue, Cairpol-type micro-sensors have been deployed on 15 measurement sites. These micro-sensors provide a perfect response to information and alert needs of the local monitoring. Indeed, completely autonomous, they have a solar panel, allowing the continuous power supply to the sensors, a GPRS module, to transmit in near-real time the gas concentrations remotely in the Caircloud® interface. The network recovers one minute data, every ten minutes. The data transmitted, via an FTP server on a website, are viewed continuously, and can thus be processed on a daily basis or even on request in case of specific events.
Easy to install, these sensors allow continuous, near-real-time monitoring of population exposure to H2S and NH3 concentrations. They are located as close as possible to stranding areas but also to the population, particularly so-called sensitive people, in schools, nurseries, hospitals, etc...
During the first year of implementation, reliability tests were carried out in-situ to validate the data transmitted. Thus, the Cairpol network is a reliable and efficient network that perfectly meets the needs of local issues.
Currently, 15 Cairpol sensors form the fixed measurement network, which can however be readjusted according to the arrival of the phenomenon, the impacted populations and the dispersion of the gases.
In front of the health impact of the gases emitted by the putrefaction of Sargasso algae, ADEME Martinique, the Martinique Regional Authority, the Martinique Regional Health Agency and the communities in the North and South of Martinique have joined forces, with the support of Madininair, to set up a network for monitoring compounds emitted by the putrefaction of Sargasso algae.
Currently, this network of 15 Cairpol sensors will be reinforced by the deployment of 4 other sensors. In addition, a mobile network of 9 sensors allows to respond to specific requests: spatialization of hydrogen sulfide concentrations at the scale of a district, assessment in areas not covered by the fixed network, etc...
NB. Each Cairnet air quality monitoring station is containing Cairsens sensors for the measurement of H2S and NH3 and is equipped with solar panels and batteries in order to be completely self-sufficient and highly mobile. Their complete GPRS communication system automatically transmit data to the CairCloud, the ENVEA’s Cloud data processing application. The recorded real-time concentrations is daily reported to the public through the DEAL (Directorate of the Environment, Planning and Housing) and the Gwad’air websites.