"The Edu-Logger nitrate sensor can be used to measure the concentration of nitrate ions (NO3-) in aqueous samples. Nitrates are used in fertilizers and can contaminate water. Also, untreated human sewage can be a source of nitrate contamination. All this can be studied with the nitrate sensor. Nitrate measurements can also be very relevant to study the nitrogen cycle in general and to relate this cycle to plants and algae. As with all Edu-Logger Sensors this must be used with the Edulogger USB module or the Wi-Fi module. " ( 900-259 )