Photosynthesis, chlorophyll integrity, and spectral reflectance in lichens exposed to air pollution.

The major objective of the present study was to identify the relationship of physiologial parameters of the photosynthetic system with the elemental content of the lichen Ramalina lacera (With.) J.R. Laund. Thalli of R. lacera were collected in an unpolluted site and transplanted in a national park and an industrial region in Israel for 8 mo. Analyses of photosynthetic activity, chlorophyll integrity, spectral reflectance, and amount of 11 metals were performed after this period of exposure. The normalized difference vegetation index (NDVI), indicative of the spectral reflectance response of the thallus, correlated with photosynthetic rate and chlorophyll and K content and correlated inversely with amounts of Ba, Cr, Cu, and Ni. The NDVI appears to enable the detection of early signs of pollutant-induced stress before changes in other physiological parameters become apparent. Elevated amounts of Cr, Cu, Fe, Mn, Ni, and Zn in lichens transplanted to an industrial area and the correlation of Mn and Ni, Mn and V, Ni and V, Fe and Mn, Fe and V, and Fe and Zn point for the greater part to metal processing in a steel smelter. Correlations of Cr and Ni, Cu and Ni, Zn and Cu, Cu and Mn, and Zn and Ni could be related to metal processing in the industrial area but indicate also vehicular activity as a possible originator.

Transplanted lichens in and around the Mount Carmel National Park and the Haifa Bay industrial region in Israel: physiological and chemical responses.

This study investigated the impact of air pollution on the spectral reflectance of the epiphytic lichen Ramalina lacera, indicated by the normalized difference vegetation index (NDVI), on the integrity of chlorophyll, indicated by the ratio OD435 nm/OD415 nm, and on the integrity of cell membranes, indicated by electric conductivity. Data relating to physiological parameters of injury were integrated with data concerning the detrimental deposition of mineral elements. The transplanted lichen, originating in a relatively unpolluted site in Israel, was placed in 17 sites on and around the Carmel Mountain and in 2 sites in an industrial region in the Haifa Bay, northwest Israel, for a period of 10 months. The accumulated amounts of Ca, Ti, Cu, Mg, Fe, Si, Ni, Zn, V, Cr, Mn, Cl-, K, F-, Na, Ba, Sr, B, S, P, Al, PO(3-)(4), SO(2-)(4), and NO-3 were related to alterations in spectral reflectance and injury caused to chlorophyll and cell membranes. At the end of the period of exposure, the retrieved transplants from the Haifa Bay exhibited low NDVI values and low OD435 nm/OD415 nm ratios, indicating chlorophyll degradation, and high electric conductivity values, indicating damaged cell membranes. NDVI values correlated positively with OD435 nm/OD415 nm ratios and negatively with accumulated amounts of Ba, Cu, Ni, S, SO(2-)(4), V, and Zn. OD435 nm/OD415 nm ratios correlated negatively with amounts of Ba, Cu, Ni, NO(-)(3), SO(2-)(4), and V. Values obtained for electric conductivity correlated positively with amounts of B, Ba, Cl-, Cr, Cu, Na, Ni, NO(-)(3), S, and SO(2-)(4). Both elemental and ion content and the physiological status of the R. lacera transplants indicated that the greater part of the biomonitoring sites on and around the Carmel Mountain were slightly polluted or unpolluted, whereas the Haifa Bay region was rather polluted. The greater part of the Haifa Bay pollution derives from the combustion of heavy fuel oil.