Heavy Metals in bark as an indicator of atmospheric deposition near ex-tin mines in Perak

Malaysia has long been recognized as one of the world's leading tin producers in 1960's.
However, over the last 15 years, the tin industry collapsed due to exhaustion of tin
deposits, low tin prices and high operating costs. Generally, the former tin mines are used
for housing development, agriculture and recreational purpose. However, most former
mines are used for crop production. These crops can cause the heavy metal to enter the
food chain. Studies have shown that crops grown on these former mining sites have high
levels of arsenic, mercury, cadmium and lead. Heavy metals release will cause harmful
impact to the environment especially to the human health. There are three types of heavy
metals pathway from mine site released to the surrounding. The pathways are from soil,
river and atmospheric deposition. The scope of study is atmospheric deposition near tin
mines. Tree barks from different trees will be used as a bio-monitoring indicator. Tree
barks have been used successfully to monitor the levels of atmospheric metal deposition
in many areas, but rarely in Malaysia. The objective of study aims to determine the heavy
metals contain in tree barks as an indicator of atmospheric deposition near several ex-tin
mine at Perak in relation to mine activity and also in relation to height of barks. Barks are
taken from three ex-tin mines site at Tronoh, UTP and Malim Nawar. Samples are
extracted using a stainless steel knife at an average size of 15 em x 15 em at different tree
height from ex-tin mines. The samples then were analyzed for Lead (Pb) and Zinc (Zn)
using atomic absorption spectrometry (AAS). Results showed that the concentrations of
heavy metals in barks are range between 13.49 mg/kg to 49.35 mg/kg for Ph and 9.46
mg/kg to 46.12 mg/kg for Zn. It is found that there are an inverse relation between height
and concentration, where with increased height of barks, the concentration of heavy
metals decreased. It was concluded that there still have a dispersal of heavy metal from
ex-tin mine even it was a non-active site.