Effects Of Heavy Metals On The Air Pollution Tolerance Indices ( Apti ) Of Five Medicinal Plants Growing Within Quarry Site In Ishi-Agu, Ebonyi State, Nigeria.

ABSTRACT

Effects of heavy metals on the Air Pollution Tolerance Indices (APTI) of five

medicinal plants growing within quarry site in Ishi-Agu, Ebonyi State, Nigeria

were studied. Following laboratory analysis of the leaves of the plants for metal

load and four biochemical parameters of APTI computation. The metal load was

determined by the Atomic Absorption spectrophotometric method, while the

ascorbic acid was determined by the titremetric method, leaf extract pH by the

electro-chemical techniques, relative water content by plant turgidity mass and

the total chlorophyll, by spectrophotometric method. Foliar photomicrography

of the leaf was also studied. Results of Plants from experimental site showed

changes in physical and internal structures of the leaves that lead to closure of

some stomata pores in test plants and damage of some epicelluler cells.

Quantification of phytochemical contents of the test plants showed higher

values than that of control which may be due to the multiplication of some

organic substances caused by oxidative stress, presence of inorganic subtances

like heavy metals and lime stone dust.The result of elemental analysis of both

experimental and control plants gave the range of concentration of the metals

in parts per million (ppm) as follows: - lead ( 2.75 – 14.13 ± 0.02); Nickle

(0.27 - 0.54 ± 0.01) ; Cadmium ( 2.25 - 24.30 ± 0.03); Zinc (0.11- 0.03 ±

0.02); and Arsenic (0.10 - 0.70 ± 0.04). Control –Lead ( 0.00 – 5.52 ± 0.01);

Nickle (0.13 – 0.23 ± 0.01); Cadmium (0.00 - 12.00 ± 0.03); Zinc ( 0.06 – 0.10

± 0.03); and Arsenic (0.02 – 0.20 ± 0.02). There was slight increase of

Cadmium above maximum daily permissible intake in C. ferruginea, A,

djalonensis, and R. communis, also there is high content of Arsenic in

R.communis which is the cause of oxidative strees in test plants that result in

the elicitation of antioxidants from plants and multiplication of ascorbic acid

content. The values for the percentage computation of APTI in test plants are

V.doniana (11.03), C.ferruginea (7.62), A.djalonesis (9.94), R. communis (11.5)

and M. esculenta (8.60). Control pants gave V.doniana (11.86), C.ferruginea

(8.21), A.djalonesis (11.86), R. communis (14.39), and M. esculenta (10.21)

that result in reduction of Relative water content, Ph value, Total chlorophyll

content and Ascorbic acid content.There is relative high content of heavy

metals, physiological and visible changes in some sensitive test plants. Owing

to information gotten from the result of this research it is not recommended that

plants from the quarry sites be used in herbal formulation because of possible

metal intoxication and attenuation of their phythopotency.