See https://github.com/EnvironmentOntology/envo/issues/1102 for a possible design pattern.
Uses undesirability standard, compared to polluted river's ecological impact standard. What is the relation to ENVO:00002114 'chemically enriched sediment'? Does 'element' in the definition refer to something found in the periosic table (like selenium) or the member of some set, aka an entity?