Daniele Tirelli

Remote sensing of chlorophyll a fluorescence of vegetation canopies: 1. Near and far field measurement techniques

Abstract This article presents instruments and techniques, used in several vegetation monitoring experiments. Simultaneous monitoring was performed with different approaches, including fluorescence lidar and passive remote sensing, leaf level reflectance, and laser fluorimetry, and compared with physiological measurements. Most of the instrumentation described was designed and built for this application. Experiments were carried out in the laboratory and in the field, to investigate the relationship between chlorophyll fluorescence spectra and plant ecophysiology. Remote sensing, spectroscopy, and ecophysiology data were then collected by an intensive research team, joining different experiences and working in national and international projects.

Detection and characterization of biodeteriogens on stone cultural heritage by fluorescence lidar

Biodeteriogens are an important cause of the weathering of a monument, particularly those made of stone, and their detection at an early stage of development helps to protect the monument from deterioration. Frequent mapping of biodeteriogen accumulation is therefore highly necessary. The use of fluorescence lidar for this purpose was introduced in 1995 and has been developed in subsequent years. Three main aspects emerged during this research: the possibility of discriminating between different biodeteriogen strains, the minimum detectable quantity of biodeteriogens, and the control of the efficiency of biocide treatments. We describe the results of a laboratory experiment devoted to clarifying these three aspects of biodeteriogen monitoring by means of fluorescence lidar.

Fluorescence lidar technique for the remote sensing of stony materials in ancient buildings

Lidars have already been used as an effective tool for the monitoring of marine environment and vegetation. In this paper the data relative to the first fluorescence lidar experiments on the facades of historical buildings are presented and discussed. The lidar fluorescence spectra presented in this paper were detected with a high spectral resolution fluorescence lidar on the Baptistery of Parma and mainly refer to the coatings of Ammonitico Rosso Veronese, a calcareous stone widely employed as decorative material for its color and typical texture. These data were also compared to the lidar spectra of samples coming from different sites situated in the extraction areas historically known from the archives and from sites in an area exploited only quite recently. The results constitute a first step towards a completely non destructive spectral analysis directly on the surfaces of the historical buildings.

Lidar remote sensing of stone cultural heritage: detection and characterization of biodeteriogens

Different kinds of organisms can grow on stone substrata. Their presence causes effects, which range from low to severe chemical and physical alterations. Up to now, methodologies are not available to investigate in situ biodeteriogens on stone monuments. The paper discusses the use of the laser- induced fluorescence for the detection and characterization of biodeteriogens on stone monuments on the base of the experiments recently carried out by the authors. Dolomitic marble samples inoculated with different cell concentrations of two biodeteriogen have been analyzed in controlled conditions. The fluorescence spectra are compared in order to investigate the possibility of detecting the biodeteriogens at an early state of development, of identifying them by the spectral signature, and of monitoring the effect of biocidal treatments. Although further investigations are necessary the results confirm the potential of this technique in the non- destructive, remote monitoring of biodeteriogen.

High-resolution lidar fluorescence spectra for the characterization of phytoplankton

The Laser Induced Fluorescence (LIF) technique has been widely employed for the study and the monitoring of the phytoplanktonic population in the marine environment. Herein a method for the characterization of different phytoplanktonic species by means of a high spectral resolution lidar fluorosensor is presented. The method is based on the detection of the changes in the peak position of the fluorescence of the chlorophyll a that is contained in all phytoplanktonic species. These changes are probably due to the proteic compounds that are present together with the chlorophyll in the thylakoid membranes within the chloroplasts and that vary with the phytoplanktonic species. The main advantage is that this method does not require the presence of characteristic fluorescence features of other light harvesting pigments, such as carotenoids or phycobilines, so that it can be used also with species where only chlorophyll fluorescence is present. Moreover, the light harvesting pigments usually show a weak fluorescence because of the strong resonant coupling between them.

Fluorescence lidar technique for the monitoring of biodeteriogens in cultural heritage studies

Fluorescence techniques have been extensively used for the detection of photoautotrophic organisms. In particular, fluorescence lidars have been successfully employed for the detection and identification of phytoplankton in sea water and, more recently, have been regarded as powerful tools for vegetation monitoring, especially as for the evaluation of forest decline. In this paper the fluorescence lidar technique is proposed as a new tool for the remote monitoring of photoautotrophic biodeteriogens on surfaces of historical monuments. The use of fluorescence lidars can remotely detect photoautotrophic organisms on monuments and, with a suitable spectral resolution, identify the pigments contained into. The advantages of the fluorescence lidar technique with respect to the traditional methods are manifold and can lead to a fast, extensive control of the stony cultural heritage at low cost. Laboratory and lidar experiments were carried out on different stony materials inoculated with microalgal and cyanobacterial species at different cell concentrations to investigate the potentialities of this technique. The experimental results presented in this paper include the remote detection of biodeteriogens on stony materials at a previsual growth stage by means of a fluorescence lidar and the identification of the fluorescence features of different pigments.

Fluorescence responses of Mediterranean sea grass Posidonia oceanica: Summer 1997 ATOM-LIFT campaign

Aquatic vegetation studies were carried out from Tuesday July 15th, 1997 to Tuesday July 22, 1997 in a sea-side aquarium- laboratory in the city of Livorno on the Tyrrhenian Sea. The investigations involved an important sea grass species Posidonia oceanica that is the main higher aquatic vegetation found in the Mediterranean Sea. Fluorescence measurements were acquired on the aquatic plants treated with different levels of Mercury and Cadmium heavy metal contamination. The measurements included steady state fluorescence and fluorescence induction kinetics, pigment extraction, and photosynthetic gas exchange rates. Fluorescence instrumentation used for the studies included the high spectral resolution fluorescence lidar System (FLIDAR

Lidar remote sensing of stony cultural heritage: detection of protective treatments

CPY), the NASA/USDA Fluorescence Imaging System (FIS), and Perkin Elmer Spectrofluorometer. Fluorescence responses showed a significant variations within the leaf as a function location from the base. Heavy metal treatments resulted in distinguishable differences in fluorescence responses.

Remote sensing of coastal waters: the IROE activity in the PRISMA project

To stop, or at least to reduce, the weathering of the stone surface its strength is often improved by treatments of different chemical composition. The uniform distribution of the treatment and the conservation of its integrity during the years are crucial factors for a good protection of the monument. As a consequence a technique which allows a remote mapping of the treatment and its characteristics would be very attractive. This paper describes the first experiments devoted to the use of fluorescence lidars in the monitoring of protective treatments on stone surface. Although further investigations are necessary the first results demonstrate the possibility of a detection and characterization of protective treatments by fluorescence lidars.

Fluorescence responses and photosynthetic rates of sunlit and shaded leaves of Italian alpine forest species: Summer 1997 ATOM-LIFT campaign

The PRISMA is a research project, sponsored by the Italian Ministry for University and Scientific Research, devoted to the study of the Adriatic Sea. Within this project, the general goal of the IROE has been the development of a measurement procedure for the detection of marine fronts which integrates the NOAA-AVHRR imagery and the fluorescence lidar data. The paper reports the activity performed during the different measurement campaigns and discusses the results obtained during the first winter campaign carried out in February 1997. A good agreement was found between the front position as detected on the AVHRR thermal images and the position detected by the fluorescence lidar on the base of the change in chlorophyll and DOM concentration as well as in the change of the water Raman signal.