What are coexistent metals? In ACS Sustainable Chem. Eng. 2018, 6 (10), 12542–12561, I saw the term &quot;coexistent metals&quot;, but I could not find a definition for that on the Internet. So what does it mean?

Karapinar et al. utilized ammonium-loaded zeolite as a seeding material for precipitating calcium phosphate and suggested the possibility of using the precipitate-ammonium loaded zeolites as fertilizer. The efficiency of chemical precipitation is affected by alkalinity, organic matter content and the coexistent metals.
I see no special meaning there, aside of the common English. It means eventual metals present in the solution as side components or impurities, aside of calcium. Like alkali metals, magnesium, heavy metals as iron, manganese, copper atc.