Micro-morphological analysis of foliar uptake and retention of airborne particulate matter (PM)-bound toxic metals: implications for their phytoremediation

ABSTRACT

While airborne particulate matter (PM) pollution is a serious problem for urban environments, it can be reduced through uptake by plant leaves. In this study, we investigated and compared the uptake of PM-bound toxic metals by different plant species. Enrichment factor (EF) and correlation analyses across different sample types indicated anthropogenic origins of these toxic metals with airborne source signatures. Scanning electron microscopy (SEM) analyses of both leaf surfaces (adaxial and abaxial) suggested that the micro-morphological properties of the leaf surface (e.g. stomata, trichomes, epicuticular wax, and epidermal appendages) control the accumulation of PM and associated metals in plant leaves. Senna siamea leaves showed the most micro-morphological variation as well as the maximum concentration of toxic metals. It was found that foliar uptake of PM-bound toxic metals is affected by leaf surface morphological characteristics. Our results imply that plant speciation strategies can be used to help decrease PM pollution.

KEYWORDS:

• Foliar dust
• urban environment
• leaf surface morphology
• green belt development
• pollution management

Acknowledgments

T.G. thanks UGC, New Delhi (India) for providing RGNF (RGNF-2012-13-SC-MAD-32632). S.K.P. acknowledges financial support from a UGC (New Delhi, India) start-up grant [No. F. 20-1/2012(BSR)/20-2(3)/2012(BSR)] and a UGC-MRP grant [F. No.-43-311/2014 (SR)]. This study was also supported by a grant from the National Research Foundation of Korea (NRF), which is funded by the Ministry of Science, ICT, & Future Planning (No. 2016R1E1A1A01940995). We acknowledge the University Science Instrumentation Centre of Dr. H. S. Gour University, Sagar, India for SEM analysis and the staff at the Bose Institute, Kolkata (SAIF) for metal analysis. All authors gratefully acknowledge the constructive criticism provided by two anonymous reviewers which immensely helped in improving the final version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by National Research Foundation of Korea (NRF) [grant number 2016R1E1A1A01940995]; University Grants Commission [grant number 20-1/2012(BSR)/20-2(3)/2012(BSR), 43-311/2014 (SR),RGNF-2012-13-SC-MAD-32632].

Notes on contributors

Triratnesh Gajbhiye

Dr. Triratnesh Gajbhiye is an Assistant Professor of Botany at Government Shankar Sao Patel College Waraseoni, M.P. His research interest includes air pollution which mainly focuses on foliar uptake of airborne toxic metal bound with particulate matter.

Sudhir Kumar Pandey

Dr. Sudhir Kumar Pandey is an Assistant Professor in Department of Botany, Guru Ghasidas Vishwavidyalaya (a central University) Bilaspur (C.G.), India. His research focuses on analysis of emerging air contaminants, plant-atmosphere exchange of trace gases, and foliar transfer of airborne toxic metals.

Tanzil Gaffar Malik

Dr. Tanzil Gaffar Malik is a Postdoctotal Researcher at Physical Research Laboratory, Ahmedabad. His area of research is air pollution with special reference to biogeochemical cycle of trace gases.

Ki-Hyun Kim

Dr. Ki-Hyun Kim is a Distinguished Professor in Department of Civil & Environmental Engineering, Hanyang University, Seoul. His research work focuses on environmental analysis, air quality management, and material engineering.

Mohammed Latif Khan

Dr. Mohammed Latif Khan is a Professor of Botany at Dr. Harisingh Gour Central University, Sagar. His research work has focused on tree regeneration to the fields of biodiversity conservation, eco-restoration, ecosystem services, carbon sequestration, molecular genetics, and phylogeny.