© 2022 Taylor & Francis Group, LLC.This special issue of Analytical Letters is devoted to selected articles based on contributions from the Third International Congress of Environmental Chemistry (EnviroChem 2021). The authors have expanded their conference papers and included their latest experimental results in this special edition of Analytical Letters. EnviroChem 2021 has aimed- to promote and disseminate knowledge on various topics and technologies related to Environmental Chemistry. All articles have gone through the standard review process. The EnviroChem 2021 Conference, where chemists, environmental engineers/scientists and researchers from many countries came together, was held in Antalya Kemer, hosted by Erciyes University (ERU), Karadeniz Technical University (KTU), Muğla Sıtkı Koçman University (MSKU), and the Chemists Society (of Turkey). EnviroChem 2011 combined invited lectures, oral sessions, and poster presentations with a total of 9 invited lectures, 46 contributed oral presentations, and 41 posters. The Conference Organizers would like to thank all committee members, invited speakers, and presenters, authors and reviewers of EnviroChem 2021 who generously shared their expertise with us by presenting/reviewing their valuable contributions to this special issue. Finally, we extend our thanks to Professor David Butcher as the Editor-in-Chief of Analytical Letters and the staff of Taylor & Francis.