What is the unit commonly used to express herbicide concentration in water?

The unit commonly used to express herbicide concentration in water is parts per million (ppm). This measure indicates the amount of herbicide present in a given volume of water, making it a practical and relatable way to understand concentration levels. In aquatic pest management, knowing the precise concentration of herbicides is essential for ensuring effectiveness while minimizing environmental impacts.

Parts per million is particularly useful because it allows for easy interpretation of very low concentrations, which is often the case with herbicides where precise dosages are critical to achieve desired outcomes without causing harm to the aquatic ecosystem. Other measurements, like gallons per acre, acre-foot, and liters per hectare, are more related to area calculations rather than concentration, which is why they are not appropriate in this context.