Effluences refer to the outflow or discharge of something, typically waste or pollutants. Antonyms of effluences could include inflows, which would refer to the incoming stream of something, or emissions, which would refer to the release of something, often in the form of gas or vapors. Alternatively, synonyms for effluences could include discharges or emanations, while antonyms might include absorption or retention. Effluences are often associated with negative environmental impacts, so antonyms might include positive or beneficial effects, such as clean air or water. Ultimately, antonyms for effluences will depend on the specific context and the type of outflow being referred to.