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Mercury (Hg) is a useful heavy metal; however, it is toxic to both humans and the environment. Tree bark is an excellent bioindicator, which has been proven to be effective in studying the level of atmospheric Hg contamination. This study aimed to determine the distribution of evaporated Hg using the total weight of Hg (THg) in tree barks in Indonesia at the artisanal and small-scale gold mining (ASGM) area of Bunut Seberang Village and Lampung University, respectively. Samples were taken using purposive sampling, based on the criteria of forestry trees at a height level of 1.3 m above ground as wide as 100 cm2. The samples were analyzed by atomic absorption spectrometry and Scanning electron microscopy to determine the levels of THg and to investigate the bark structures. Results showed that the highest THg values were found in a Magnolia champaca sample (56.5 µg), followed by Swietenia mahagoni (45.8 µg) and Swietenia mahagoni (33.5 µg). All species studied showed THg levels in the tree barks at an elevation from 30 to 320 m above sea level. The Hg amounts found in the sampled barks indicated the dispersion of Hg throughout the ASGM area, which signified hazardous atmospheric conditions in the area.

The use of mercury in gold refining causes air pollution and results in the contamination of multipurpose tree species (MPTS). Tree bark has properties that cause it to store mercury for quite a long time. The purpose of this study was to determine mercury contamination of MPTS and map the mercury contamination distribution in the atmosphere using tree barks as bioindicators. Sampling was performed using purposive sampling. The mercury concentration was obtained by atomic absorption spectroscopy, and the highest THg contents were analyzed using a scanning electron microscope. The analysis was carried out by gauging total mercury (THg), distance, elevation to THg, and interpolation of THg at the research site. The results showed that there were 10 types of MPTS trees whose bark could accumulate mercury. The bark of the Tamarindus indica tree stored the greatest amount of THg (74.4 µg dry weight (DW)), followed by Persea americana (58.7 µg DW), and Annona muricata (44.2 µg DW), respectively. This result was influenced by the roughness of the bark and the location of the plants. No correlation was found between distance and elevation to THg on tree bark. The mercury interpolation in the atmosphere showed that mercury moves from the purification point to the southeast of the purification location.