Mapping Atmospheric Mercury in Lampung Province, Indonesia Using Bark of Multipurpose Tree Species

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.

Revealing ancient gold parting with silver and copper isotopes: implications from cementation experiments and for the analysis of gold artefacts

Gold parting enabled the production of very pure gold for various purposes from the sixth century BC onwards, but analytical proof of this pyrotechnical process is difficult. We describe a new analytical approach for the identification of purified gold combining silver and copper isotopic with trace element analyses. Parting experiments were performed with gold-silver-copper alloys using the classical salt cementation process to investigate potential silver and copper isotope fractionation and changes in trace element concentrations. In addition, we provide the first comprehensive dataset of silver isotope ratios of archaeological gold objects from the Mediterranean and Central Europe to test whether or not gold refining can be identified on the basis of isotope systematics. The results show that very heavy silver and copper isotopic compositions are clear evidence for parted gold, but that the application of copper isotopes might be limited.

Economic Potential of Gold in Batouri (Eastern Cameroon)

The aim of this work is the valorization of the economic potential of gold in the Batouri region. The study is undertaken on five sites of which two alluvials (Djengo and Mongonam localities) made up of flat and river gold, two eluvials (Kambele and Bote) containing gold of veins in quarries, and one semi mechanized exploitation (METALICON) working on the two previous  types. Laboratory works consist of traditional melting, determination of the various grades of gold through densimetry and spectrometry analysis and refining using the Miller Chloration method. The main results from these analyses are: i) recovery concentration is low, (about 0.5 g/t) for the traditional mining and higher with the semi mechanization (1.5-2 g/t). Densimetry and spectrometry analyses show that gold of semi mechanized sites has an average grade of about 24 carats, 22 carats and 20 for alluvial and eluvial gold respectively. ii) For 26 kg of gold refined, a weight of 16.681 kg is obtained at a cost of 4 051 946 (four million fifty one thousand and nine hundred forty six) CFA F. Spectrometry analyses reveal the presence of silver and copper impurities, elements that can still be valorized through the presence of a gold refining unit. Hence, the absence of a gold refining unit in our country leads to poor transformation of its ores and loss of devices.

Adaptation Ability of Mahogany (Swietenia macrophylla) against Mercury Contamination from Artisanal and Small-Scale Gold Mining

Contamination of mercury (Hg) in illegal gold mining waste could be reduced by the plant. The study aimed to examine the adaptability of mahogany (Swietenia macrophylla) seedling in the growing media of tailings contaminated by mercury. Tailings were taken from the gold refining industry located in Bunut Village, Padang Cermin Sub-district, Lampung Province. The study was designed in a completely randomized design for 5 treatments and 4 replications used combination of topsoil : tailings in a ratio of 100% : 0%; 75% : 25%; 50% : 50%; 25% : 75%; and 0% : 100%. Data were processed by analysis of variance at the 0,05 significance level followed by the Least Significant Difference test. The results showed that mahogany seedling had the adaptability to the media with a maximum tailings concentration of 75%. The higher concentrations of tailings tended to decrease the percentage of life, increment of diameter, increment of the number of leaves, leaf area, the increment of root length, and biomass of mahogany. The higher concentrations of tailings resulted in a better plant height increment compared to the lower concentrations, however, all concentrations of tailings in the planting medium reduced the height of the mahogany seedling.Keywords: Adaptability, mahogany, mercury, tailing