•'HA' nomenclature can be undoubtedly applied in engineering sciences.•The real structure of NOM is still a 'black box' in natural ecosystems.•Recognition of 'HA' from natural ecosystems to engineering sciences.•Alkaline extraction on NOM link natural ecosystems to engineering sciences.
Keywords: Alkaline extraction technique; Engineering sciences; Humic acid; Natural ecosystems.
© 2021 The Authors.