Page 270 - Geochemical Remote Sensing of The Sub-Surface

Aerospace detection of hydrocarbon-induced alteration 243

climax. The maple trees occur in an area of maximum methane seepage and minimum
soil oxygen content. The symbiotic mycorrhizal fungi on the root hairs of maple trees
appear better able to tolerate these anaerobic soils than their counterparts on the root
hairs of oaks. Lang et al. (1985b) searched the NS-001 data for information on the
geobotanical effects. They concluded that: an image of bands 2, 3 and 4 supplied
optimal species and species community discrimination; the ratio of bands 4:3 measured
the amount of chlorophyll; the ratio of bands 4:5 showed green vegetation biomass; and
the ratio of bands 5:7 indicated general vegetation vigour. Based on these findings, two
supervised vegetation classifications were found to be optimal, viz: (1) bands 2, 3 and 4,
band-ratio 4:5 and band-ratio 5:6; and (2) bands 2, 3 and 4, band-ratio 4:5 and band-ratio
5:7. Good accuracy is provided by these supervised classifications whereas single bands,
band-ratios and composite band-ratios yield inadequate information for discriminatory
mapping.

TABLE 7-1I

Spectral characteristics of Aircraft Thematic Mapper Simulator (NS-001) Bands 1-7

Band Centre and window (lam) Features Applications
1 0.49 0.45 - 0.52 Absorption features due Deciduous / coniferous
to chlorophyll and differentiation
carotenoid
2 0.56 0.52 - 0.60 Chlorophyll reflectance Assessment of vegetation
peak; sensitive to green vigour
pigmentation
3 0.66 0.63 -0.69 Maximum chlorophyll Species differentiation
absorption and assessment of
vegetation vigour
4 0.83 0.76 - 0.90 Reflectance peak sensitive Species identification and
to leaf area, vegetation assessment of vegetation
density, biomass vigour
5 1.15 1.00 - 1.30 Fine spectral structure,
sensitive to leaf area
6 1.65 1.55 -I.75 Absorption characteristic Moisture status
of leaf water mass
7 2.22 2.08 - 2.35 Absorption attributed to Moisture status
water molecules within a
leaf

Biogeochemical analysis of leaves of trees over the Pollard oil field, Alabama,
indicates anomalous concentrations of Mn. Correlation analysis reveals a statistically
significant relationship between biogeochemical Mn anomalies and producing wells.