[H-GG02] Use, change, management of natural resources and environment: Interdisciplinary perspectives

[HGG02-03] Preliminary environmental magnetic results from heavy metal contamination around the Erdenet Cu-Mo deposit, Mongolia.

*Kazuo Kawasaki¹, Ryuki Tonami², Solongo Tsetsgee³, Baasansuren Gankhurel³, Keisuke Fukushi⁴ (1.Graduate School of Science and Engineering for Research, University of Toyama, 2.Department of Earth Sciences, University of Toyama, 3.Kanazawa University, 4.Institute of nature & Environmental Technology, Kanazawa University)

Keywords:Environmental magnetism, Heavy metal contamination, Erdenet Cu-Mo deposit, Mongolia

The Erdenet Cu-Mo porphyry deposit in Mongolia is one of the largest mines in the world and it has been operating since 1978. The ore processing waste is pumped into a tailings pond that contains ~400 million tons of tailings and 15 million m³ of supernatant water. Environmental magnetic results are reported here for surrounding topsoils, stream sediments and sediments from the pond. The rock magnetic analyses indicate that the main magnetic minerals are pseudosingle domain magnetite and/or partially oxidized magnetite with minor pyrrhotite. This magnetic mineralogy is consistent through all samples, indicating that the observed fluctuations of magnetic susceptibility and saturation isothermal remanent magnetization (SIRM) intensity record the abundance of magnetic minerals in the samples. Based on geochemical analyses of the topsoils and stream sediments, positive correlations are found between susceptibility and SIRM intensity with heavy metal concentrations such as Cr and Zn. Further, SIRM intensity showed a more positive correlation with heavy metal concentration than susceptibility, implying that some of magnetite may be substituted by metal ions. These results indicate that environmental magnetic monitoring, especially the SIRM intensity, can be a rapid and cost-effective method for studying the spatial distribution of heavy metals in the Erdenet area.