Which of the following pollutants can be monitored continuously?

The ability to monitor pollutants continuously is crucial for ensuring compliance with environmental standards and for protecting public health. pH is a particularly suitable parameter for continuous monitoring because it can change frequently and is essential in various environmental contexts, especially in water quality management.

By continuously monitoring pH, operators can quickly detect and respond to changes that may indicate potential contamination or other environmental issues. pH meters are designed for real-time measurements and can provide immediate data, allowing for timely interventions if levels fall outside acceptable ranges.

In contrast, while hydrogen, carbon dioxide, and mercury can also be monitored, the methods and practicalities of continuous monitoring vary for these substances. For instance, monitoring carbon dioxide is typically done using sensors designed for specific applications, and mercury monitoring is often more complex and may require sampling rather than continuous analysis due to challenges associated with its detection and the need for specialized equipment.