Remote monitoring of seawater temperature and pH by low cost sensors

Monitoring chemical and physical properties of seawater is important to assess the status and predict future changes of marine environment. Among possible parameters, pH and temperature are frequently measured since they directly affect chemical and biological systems. Seawater assessment, conventionally performed in situ, is labour intensive and time consuming, but now remote sensor networks promise to become a viable tool to obtain spatial and temporal information over a wide range. Here we describe the development and validation of an autonomous system for the remote monitoring of pH and temperature in seawater. The device consists of a graphene-based pH sensor, a thermistor, an electronic readout, a smartphone and a power unit. After deployment in a marine testing site at the Livorno harbour in Italy, the system published on the web pH and temperature data for more than a week, whose accuracy was confirmed by comparison with a reference system.