麻豆传媒

This study involves an examination of Mn in the environment in central Nova Scotia. Since Mn has been mined and occurs in many localities, the study was initiated in order to determine whether Mn could possibly pose an environmental risk, and where. The aims are to: 1) examine the occurrence of Mn mineralization within Carboniferous rocks and the Meguma Supergroup, 2) develop a GIS database of Mn concentrations in surface water, lake sediment and till, in central Nova Scotia, 3) investigate the relationship between Mn in the surface environment and Mn occurrences in bedrock and, 4) gain more insight into Mn cycling in the environment. Mn is concentrated in the environment by natural as well as anthropogenic processes. High concentrations of some Mn species are toxic to some flora and fauna. In the human population, elevated Mn in municipal water supplies is considered a nuisance leading to the staining of clothes and water fixtures; in some cases expensive water treatment facilities are required. The formation of secondary Mn oxide and hydroxide minerals is an important control for the cycling of some toxic, heavy metals through the surface environment. Many variables drive Mn cycling, including oxidizing/reducing conditions, the availability of oxygen, and pH of co-existing aqueous solutions.

In central Nova Scotia, sedimentary rocks within the Carboniferous Windsor Group and Horton Group, and metasedimentary rocks of the Cambro-Ordovician Meguma Supergroup host Mn mineralization. X-ray diffraction indicates that pyrolusite and hematite are the main Mn-bearing minerals in the Carboniferous rocks studied. In the Meguma Supergroup, Mn-rich garnet, ilmenite, and in some areas, Mn-rich carbonate minerals occur. Results indicate that Mn is enriched in surface water and lake sediment overlying the Carboniferous rocks compared to surface water and lake sediment overlying the Meguma Supergroup. Till overlying the Meguma Supergroup is enriched in Mn compared with till overlying Carboniferous rocks. The mean Mn concentration of surface water (88.8 ppb) within the study area exceeds the acceptable Canadian limits for drinking water (0.05mg/L = 5 ppb).

Keywords:
Pages: 115
Supervisor: Don Fox and Marcos Zentilli