Comparative studies of air pollution tolerance indices (APTI) of some economic plants around Umuebulu Gas Flare Station in Rivers State, Nigeria

Abstract

The study examined the air pollution tolerance indices (APTI) of ten (10) economic plants around the gas flare station in Umuebulu community in Etche Local Government Area of Rivers State, Nigeria. Four physiological and biochemical parameters: relative water content, ascorbic acid, total chlorophyll and pH of the leaf extracts were used to compute the APTI values. Plants were classified into three categories of sensitivity: APTI < 8.11 below = sensitive, APTI 8.12 to 8.14 = intermediate and APTI > 8.15 above = tolerant. The APTI values ranged between 10. 47 for Elaeis guineensis Jacq. and 6.82 for Mangifera indica L. Six plant species had significantly (P < 0.05) higher APTI values than the other four. The results showed that combining a variety of these parameters gave a more reliable result than that of individual parameters. The order of tolerance is as follows: Elaeis guineensis < Manihot esculenta Crantz < Ocimum gratissimum Mint < Carica papaya L. < Solanum incanum L. < Vernonia amygdalina Del. < Musa sapientum Ktze < Newbouldia laevis (P. Beauv.) < Psidium guajava L. < Mangifera indica. The order of tolerance showed Elaeis guineensis as the most tolerant species, while Mangifera indica was the most sensitive species to air pollution stress in the station. T-test between experimental and control plants showed that the APTI values of most of the control plants were significantly (p < 0.05) higher than those of the experimental plants. The physiological parameters showed higher ascorbic acid content, lower total chlorophyll content, lower relative water content and variable pH leaf extract of the experimental plant to those of the control. The economic plants with high APTI (tolerant) are recommended for use in domestic, industrial and urban landscaping, both for their economic values and phytoremediation potentials of air polluted environment, while the plants with low APTI (sensitive) can used as bio-indicators of environmental air quality.