In Situ Sensors

Low-cost in situ water quality sensing

 

There is growing interest in low-cost sensors for environmental monitoring (e.g. water quality) from the point of view of economic viability for integration into widescale in situ sensor networks, such as that envisioned by the AquaWatch Australia project and in their potential to fill gaps between conventional, more expensive, sensor installations. Aquatic Remote Sensing (AqRS) team members have been involved in the development of several technologies in this space:

HydraSpectra

HydraSpectra is an above surface reflectance sensor that exploits the physically based principle that spectral reflectance signals emanating from algal-dominated waters contain information which can be related to the presence and amount of important water quality parameters, including pigments present in phytoplankton.

Designed for continuous deployment affixed to bridges, pylons, jetties and buoys, HydraSpectra measures the required spectra to accurately determine spectral reflectance. From the spectral reflectance we can accurately estimate the concentrations of algal biomass and other water quality parameters (sediment, turbidity, water clarity, dissolved colour) present in surface waters.

The device has in-built comms to transmit data for real time water quality alerting.

 

 

Example HydraSpectra deployment in Cockburn Sound Western Australia showing reflectances measured and time sequence of changes in chlorophyll a concentrations.

 

NocTurbis low-cost nitrate sensor

 

Nitrate is a core nutrient in biological productivity in aquatic ecosystems, contributing to the growth of algae which can lead to environmental problems when present in excess concentrations. The current cost of commercial nitrate sensors, prohibits integration into widespread in situ water quality sensor networks. Funded by CSIRO’s Autonomous Sensing Future Science Platform (FSP), members of the AqRS team have been investigating the development of a low cost and accurate optical nitrate sensor suitable for monitoring freshwater inland aquatic environments. Named NocTurbis, the sensor also incorporates optical turbidity (a measure of suspended particulate matter) and dissolved organic carbon (DOC) sensors using a novel optical and electronic approach. The sensor also incorporates biofouling control measures.

 

 

  1. Artists impression of the NOCTurbis sensor
  2. Initial field testing of the NocTurbis device.