PAR measurements are important because the rate of photosynthesis directly relates to the penetration of light throughout the water column. Also, high levels of PAR can indicate photoinhibition. PAR levels vary due to the natural attenuation by water and the presence of absorbing algal pigments, dissolved organic material, and scattering by particles.YSI measures PAR using a single or dual Li-Cor sensor attached to a YSI 6600 water quality sonde for continuous field monitoring.

YSI offers several PAR systems that can be directly integrated into existing or new 6600 multiparameter sondes. PAR sensors are powered by the sonde and PAR data is added to the data stream of the water quality sonde. This eliminates a separate data logger for PAR and enables long-term studies without requiring a surface data logger.

Choose between single or dual, wiped or unwiped LI-COR 2π PAR sensors or a single unwiped LI-COR 4π PAR sensor. Use PAR sensors for:

• Measurement of light attentuation
• Primary productivity studies
• Development of Photosynthesis-Irradiance (P-I) curves
• Photoinhibition studies
• Submerged Aquatic Vegetation (SAV) studies
• Measurement of the euphotic zone
• Investigate absorbing material such as DOM, pigments, or gelbstoff
• Measurement of Photosynthetic Photon Flux Density (PPFD)

PAR Systems for Unattended monitoring include:

• Upper and lower stainless steel mounting brackets
• Sensor mounting arm bracket set for 0.5 meter sensor separation
• 2 PAR sensor electronics
• 2 five-pin wet-pluggable PAR connectors with dummy plugs

PAR Systems for Manual profiling include:

• Stainless steel mounting brackets
• Sensor/counterbalance mounting arms and collapsible brackets
• 2 channel PAR sensor electronics
• 2 PAR connectors with dummy plugs