Global nuclear radiation monitoring using plants

Abstract

Plants exhibit complex responses to changes in environmental conditions such as radiant heat flux, water quality, airborne pollutants, soil contents. We seek to utilize the natural chemical and electrophysiological response of plants to develop novel plant-based sensor networks. Our present work focuses on plant responses to high-energy radiation – with the goal of monitoring natural plant responses for use as benchmarks for detection and dosimetry. For our study, we selected a plants cactus, Arabidopsis, Dwarf mango (pine), Euymus and Azela. We demonstrated that the ratio of Chlorophyll a to Chlorophyll b of the leaves has changed due to the exposure gradually come back to the normal stage after the radiation die. We used blue laser-induced blue fluorescence-emission spectra to characterize the pigment status of the trees. Upon blue laser excitation (400 nm) leaves show a fluorescence emission in the red spectral region between 650 and 800nm (chlorophyll fluorescence with maxima near 690nm and 735 nm). Sample tree subjects were placed at a distance of 1m from NIST-certified 241AmBe neutron source (30 mCi), capable of producing a neutron field of about 13 mrem/h. This corresponds to an actual absorbed dose of ~ 1 mrad/h. Our results shows that all plants are sensitive to nuclear radiation and some take longer time to recover and take less. We can use their characteristics to do differential detection and extract nuclear activity information out of measurement results avoid false alarms produced environmental changes. Certainly the ultimate verification can be obtained from genetic information, which only need to be done when we have seen noticeable changes on plant optical spectra, mechanical strength and electrical characteristics.