Bark of Neem Tree (Azadirachta indica) as Bioindicator for Deposition of Heavy Metals around Katsina Steel Rolling Company in Katsina Township

The bark of neem tree (Azadirachta indica) is used in this study as bio-indicator to monitor heavy metal pollution in Katsina township. Plants can take-up heavy metals from the soil and water via their roots and from the atmosphere via the leaves. The uptake, accumulation and translocation of heavy metals in plants may vary in different species due to anatomical and physiological differences. Barks are sampled from four sites in Katsina township, which include; Katsina Steel Rolling Company Round-about (Site A), Kofar Kwaya Round-about (Site B), Kofar Yandaka Round-about (Site C) and neem tree plantation opposite Nigeria Army Barrack, Natsinta (Site D). The samples are analyzed for Iron, Manganese, Copper, Lead, Cobalt, Chromium, Nickel and Zinc using atomic absorption spectrophotometry (AAS). The results obtained reveal heavy metal levels (µgg– 1) ranging from 52.50 – 196.25 (Fe), 19.50 – 34.25 (Mn), 2.41 – 8.43(Zn), <0.01 – 18.75(Cr), 3.01 – 11.50(Co), <0.01 – 3.50 (Pb), 1.00 – 4.25(Ni) and 0.13 – 2.75(Cu) across the four sites. The results also show the concentrations of iron correlating significantly with distance from the Steel Rolling Company which equally doubles as the source of contamination. The heavy metal burdens from site A are the highest while those from site D are the least, thus displaying a somewhat correlation between heavy metal loads and site distance from contamination point with the concentration of Cu, Pb and Zn as the only exception. Amidst the heavy metal analyzed, Fe has the highest concentration while Cu has the least level. It is concluded that neem bark is a good bio-monitor for air quality monitoring.