Review Basic processes in phytoremediation and some applications to air pollution control Hiromichi Morikawa a,b, * , € Ozg€ ur Cem Erkin a a Department of Mathematical and Life Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan b Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Corporation (JST), Kawaguchi, 332-0012, Japan Abstract In this short review, basic processes for phytoremediation and plant enzymes that are potentially useful in phyto- remediation are briefly summarized. The remaining part describes the applications of the basic processes to decon- taminate pollutants in the environments that have been done in our laboratory. Our work includes (1) analysis of the capability of various naturally occurring plants to decontaminate atmospheric nitrogen dioxide and selection of nitrogen-dioxide-philic plants that grow with nitrogen dioxide as the sole nitrogen source, (2) production of transgenic plants to improve plantsÕ capability to decontaminate atmospheric nitrogen dioxide, and (3) analysis of the denitrifi- cation process in plants to innovate a gas–gas-converting plants that convert nitrogen dioxide to nitrogen gas. Ó 2003 Elsevier Ltd. All rights reserved. Contents 1. Introduction ......................................................... 1553 1.1. Basic processes for phytoremediation ................................... 1554 1.2. Enzymes that are potentially useful in phytoremediation ...................... 1555 2. Applications to air pollution control ........................................ 1555 2.1. Nitrogen-dioxide-philic plants from nature ............................... 1555 2.2. Transgenic plants for NO 2 pollution control .............................. 1555 2.3. Gas–gas-converting plants that convert nitrogen dioxide to gaseous nitrogen ....... 1556 Acknowledgements ........................................................ 1556 References .............................................................. 1557 1. Introduction Phytoremediation employs the use of plants, alone or together with their associated microorganisms, to degrade, contain or stabilize various environmental contaminants in soil, water, and air (Cunningham et al., Chemosphere 52 (2003) 1553–1558 www.elsevier.com/locate/chemosphere * Corresponding author. Address: Department of Mathe- matical and Life Science, Graduate School of Science, Hiro- shima University, Higashi-Hiroshima 739-8526, Japan. Tel.: +81-824-24-7449; fax: +81-824-24-0749. E-mail address: hmorikaw@sci.hiroshima-u.ac.jp (H. Mori- kawa). 0045-6535/03/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0045-6535(03)00495-8