Final answer:
To determine the nitrate ion levels in a river, one can use a nitrate test kit, ion-selective electrodes, or spectrophotometric methods in a laboratory setting. These processes help measure nitrate concentration and protect environmental and public health.
Step-by-step explanation:
To find the level of nitrate ions in a river, you may conduct a water quality test using a nitrate test kit, which typically involves collecting a water sample and adding specific reagents that will cause a color change in relation to the nitrate concentration. Another method is by using ion-selective electrodes designed to measure the concentration of nitrates directly in the water sample. Additionally, laboratories use spectrophotometric methods for precise measurements, where a sample is treated with reagents to form a colored complex, whose absorbance is measured using a spectrophotometer to determine nitrate concentrations.
It's important to note that elevated nitrate levels can have serious environmental and health effects. For instance, levels above 10 mg/L (10 ppm) in groundwater can cause "blue baby syndrome" (acquired methemoglobinemia). Hence, monitoring nitrate levels is critical for both environmental protection and public health safety. The knowledge of nitrate presence is also essential in understanding the potential urban or agricultural origin of water contamination.