Mining is an inherently invasive and destructive activity with broad ranging and long term effects on the environment. Despite advances in regulation and oversight, pollution remains a significant and long term problem.
A recent paper by Beyer et al. examined the effects of environmental heavy metal contamination from mine tailing and run off on the white-footed mouse (Peromyscus leucopus). Working with wild caught mice in the Southeastern Missouri Lead Mining District, they examined a number of biomarker responses and histopathological results for evidence of toxic effects caused by environmental exposure to high levels of lead and cadmium. Overall mice caught at the mining sites showed reduced activity of ALAD in red blood cells – a marker for blood lead levels, and increased levels of glutathione (Arbor Assays’ Glutathione Fluorescent Detection Kit, K006-F). Increased glutathione is a marker for oxidative stress, which can negatively impact the health of individuals in a variety of ways. Mice caught at one mining site with strongly acidic soil showed significantly higher cadmium when compare to both other mining sites and at the control site. Increased cadmium levels were associated with lower glutathione levels and higher ALAD levels than other lead exposed mice. The authors used this data to develop linear regression models for relating tissue lead dosages in white footed mouse to lead concentrations measured in the soil at the collection site, which will be helpful for future monitoring at these sites and others.
In separate work, Mancera et al. studied the effects of mining machinery noise on HPA stress in field mice (Mus musculus). Noise pollution from mining machinery has been identified as a source of stress for wildlife, but little is known about specific effects on the behavior and physiology of individuals. In this study mice were exposed to either high (70-75 dB) or low (60-65 dB) amplitude machinery noise for a period of three weeks and assessed for behavior, fecal corticosterone levels (Arbor Assays’ Corticosterone EIA Kit, K014-H) and organ properties. Both noise levels increased counterclockwise circling behavior as compared to control mice, however only the high amplitude noise in however only the high amplitude noise also increased clockwise circling behavior. Clockwise circling indicates left hemisphere activation and may inhibit stress arousal by the right hemisphere. Fecal corticosterone levels, on the other hand, were elevated in the mice exposed to the low amplitude noise. This lead the authors to speculate that the dopamine-related circling at the higher amplitude may be a coping mechanism that prevented physiological HPA-axis mediated stress response. Overall their results validated both physiological and behavioral changes as a result of noise exposure.
These studies highlight just how little is known about the specific ways in which mining, even when done under tightly regulated conditions, can impact wildlife in the area of the mine. It is important to consider ecological impact as the mining industry and mining regulation evolve. Decisions on not just the placement and creation of new mines; but also things like machinery operating hours, disposal of spoil and waste water, and even how mines are ultimately closed and sites remediated at the end of use, can all have wide-ranging and long term impacts on the environments. Increasing our understanding about the details of the biological mechanisms involved in how mining impacts ecosystems will hopefully help to limit negative effects as much as is feasible and increase our ability to remediate sites more quickly and thoroughly.