SUVA is an indicator of what type of precursor substances associated with disinfection by-products?

The correct answer, humic content, reflects the importance of SUVA (Specific Ultraviolet Absorbance) as an indicator of the presence of humic substances in water. Humic substances are complex organic molecules formed from the decomposition of plant and animal materials. They play a significant role in the formation of disinfection by-products (DBPs) when chlorine or other disinfectants are used in water treatment.

SUVA is calculated by measuring the absorbance of ultraviolet light at a specific wavelength (typically 254 nm) and normalizing it to the concentration of dissolved organic carbon (DOC) in the water. A higher SUVA value indicates a greater concentration of humic substances, which are known to react with chlorine to form DBPs such as trihalomethanes and haloacetic acids. By monitoring SUVA, water treatment operators can assess the potential for DBPs formation and make necessary adjustments to treatment processes to minimize risks associated with these compounds.

The other options do not accurately represent what SUVA measures. Chlorine content pertains to the residual disinfectant levels, nutrient load typically relates to the presence of nitrogen and phosphorus that can lead to algal blooms, and soluble organic matter is a broader term that could include various substances, not solely