Laser-induced fluorescence emission (LIFE) from Lake Fryxell (Antarctica) cryoconites

Abstract

Laser-induced fluorescence emission (LIFE) images were obtained in situ from a 27 cm long ice core at Lake Fryxell, Antarctica. The excitation was accomplished with a simple 532 nm green laser pen light, and the fluorescence images were captured with a small compact digital camera. The targets for the experiment were mm-scale cryoconite assemblages found in the ice covers of this perennially frozen Antarctic lake. The fluorescence response originates from photo-pigments in cyanobacteria-dominated cryoconite assemblages with phycoerythrin (PE) exhibiting the optimal target cross section. This inexpensive, low-mass, low-energy method avoids manipulation of the in situ habitat and individual target organisms and does not disturb the microbial community or the surrounding ice matrix. We establish the correlation between fluorescence intensity and PE concentration. We show that cryoconite fluorescence response does not appear to decrease with depth in the ice cover, in agreement with similar findings at Lake Untersee, a perennially ice-covered lake in Dronning Maud Land, Antarctica. Optical reflection and refraction events at the air/ice interface can complicate quantitative estimates of total pigment concentrations. Laser targeting of a single mm-scale cryoconite can result in multiple neighboring excitation events secondary to reflection and refraction phenomena in the multiple air/ice interface of the bubbles surrounding the primary target.

A spatial investigation of the environmental controls over cryoconite aggregation on Longyearbreen glacier, Svalbard

“…Phycobiliprotein concentrations have been under-studied, with only Sattler et al (2010) exploring this avenue, utilising laserinduced fluorescence imagery to study cyanobacterial autofluorescence within ice core debris. Whilst this research has highlighted the sparse application of some techniques such as ion chromatography and nuclear magnetic resonance spectroscopy, research has focused on isolated samples or transects.…”

An Assessment of macro-scalein situRaman and ultraviolet-induced fluorescence spectroscopy for rapid characterization of frozen peat and ground ice

“…The 2018 rover mission to Mars includes a Raman spectrometer as part of the science payload (Böttger et al 2012), with capabilities comparable with the instrument used in this study (i-Raman ® System by B&W Tek). Both Raman and UIF spectroscopy have been shown to be capable of detecting the presence of a wide array of bioindicators (e.g., De Gelder et al 2007;Sattler et al 2010;Dartnell et al 2012); (in this paper we use the term 'bioindicators' as shorthand for the range of possible indicators of the presence of past or present life, including biomarkers, biomolecules and live/dead microorganisms). Bioindicators include photosynthetic pigments such as α-chlorophyll and b-chlorophyll, as well as carotenoids such as β-carotene and lycopene.…”

“…2007; Sattler et al . 2010; Dartnell et al . 2012); (in this paper we use the term ‘bioindicators’ as shorthand for the range of possible indicators of the presence of past or present life, including biomarkers, biomolecules and live/dead microorganisms).…”

An instrument design for non-contact detection of biomolecules and minerals on Mars using fluorescence

“…Previous investigations have employed the use of native fluorescence for mineral identification, organics, and photosynthetic compounds for over 100 years [ 5 - 16 ]. One such investigation examined using native fluorescence spectra of chlorophyll a and other photosynthetic pigments in their natural environment using airborne assets was first reported by Hoge and Swift [ 5 ].…”

“…A more extensive investigation using various pigment-protein Macromolecules in the 480–560 spectral region demonstrated the capability of measuring a variety of photosynthetic pigments using native fluorescence [ 6 ]. More recent investigations measured the fluorescence of several photosynthetic pigments to determine the microbial community of photosynthetic organisms [ 15 , 16 ]. A few in-situ fluorescence instruments have been developed to identify biosignatures and are at various stages of flight technical readiness levels.…”