Evaluation of levels of black in black-odor waters through absorption coefficient method

The pollution of urban waters is still challenging for many developing countries, with the formation of black-odor waters as a typical phenomenon. However, the mechanisms of such phenomenon are still unclear as some waters become black-odor repeatedly. Thus, accurate evaluations of levels of black and odor are important for mechanism analysis. The evaluation of odor levels by previous methods under ambient atmosphere is relatively straightforward. However, evaluating the levels of black is still challenging. In this short communication, a novel absorption coefficient method was developed to evaluate the levels of black in waters. The method was found to be rapid, relatively accurate, sensitive, and stable. The possible role of the absorption coefficient of particles with 254 nm (α_p(254)) in evaluating the levels of black was explored. The results showed that for α_p(254) below 20 m^-1, the waters were characterized as no black, light black between 20 m^-1 and 70 m^-1, and dark black at more than 70 m^-1. The evaluation of α_p(254) and SDD of levels of black provided consistent results, but α_p(254) was more objective than SDD. In sum, these findings provided a rational method to obtain insights into the mechanisms of black-odor waters. This short communication focused on presenting the evaluation method, while the mechanisms of formation of black-odor waters will be the topic of future investigations.