Science of the Comstock - Environment
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Environment Topics:
Introduction
Urbanization
Mine Wastes
Influence of Mining
Mine Wastes
Introduction
Aside from the regional urbanization that the Comstock Lode created, mine wastes were left behind as a major environmental legacy. Mine wastes from the Comstock, include tailings, rock, and water. To various degrees these materials contain and emit toxins into the environment.
Mines along the Carson River
The most damaging aspect of mine waste occurred along the Carson River. Poor mining practices from the latter half of the nineteenth century are entirely to blame. Mine tailings were disposed directly into the Carson River from the numerous mills that were set up along its course to treat the ores from the area. Quartz and clay sludge called tailings from the milling operations was dumped directly into the river by these mills. For a time, the added sediment load raised the riverbed and caused tailings sediment to overflow onto fertile floodplains where agricultural potential is the greatest. Further, it inundated riparian habitat along the river's course with sediment. A simplified schematic diagram found below shows the effect the mine tailings had on the floodplains adjacent to the river. Over the decades, repeated floods along the Carson River have re-established the riparian habitat and flushd the flood plain, such that today the environmental legacy of the Comstock is primarily a concern regarding mercury added during ore processing.
Natural and added toxic elements and compounds
Many toxic elements and compounds in the environment on the Comstock are naturally occurring within the ore deposit, in the surrounding mineralized rock, and in the waters that emanate from the area. These toxins are an assortment of heavy metals including arsenic. Naturally occurring arsenic is an environmental concern in many parts of the world and occurs regardless of mining. However, miners added substantial mercury to the ore during the processes of recovering the valuable metals. An article in Nevada Geology, "Mercury Contamination of the Carson River" discusses some of the results of research into the mine wastes of the Carson River.
Impact of Toxins
Mercury is quite mobile in the natural environment, and easily finds its way into water, soil, plants and animals. This is certainly true in the lower Carson River drainage. Fish within the drainage have toxic levels of mercury, and most people avoid eating them. The Environmental Protection Agency has designated the area a Superfund site, and it has been the focus of that agency's study for a number of years.
Removal of the wastes as a geologic occurrance
Because the scale of impact along the Carson River is so large, natural detoxification will occur over the eons by subsequent sedimentation, dilution and diffusion. Man will have little or no effect to detoxifying the sediments along the Carson River because the job would prove insurmountable. The presence of toxic wastes will certainly be recorded in the accumulation of sediments at the river's termination at the Carson Sink. Future geologists 100,000 years from now will find a curious sand and clay layer rich in gold silver, mercury, arsenic and other elements derived from the Comstock. This layer will have a sharp basal contact and will defuse upwards into normal sedimentation sequences. Indeed, the Carson Sink is the ultimate tailings pond for the Comstock. Ironically this is also the site of an amazing population of both migrating and non-migrating water fowl.
Modern Regulation
Within the United States pollution from such mining practices as described above has been regulated into the history books. Unfortunately, the legacy of such activity will be with us for generations to come. Today, modern mining practices in the United States include waste detoxification and disposal. It took early environmental disasters such as that which occurred along the Carson River and at other localities to create mining reform that closely regulates and enforces strict compliance to high standards of mine waste disposal and treatment within all states of the union.
Environment and use of resources
Today mining practices in the United States must adhere to reasonable and sound regulations that provide a blend of environmentalism and economic exploitation. Indeed, the two philosophies seem to be polar opposites, but as long as humans continue to use natural resources, there will be a need for mining and for environmental regulation and the safeguards they provide.
Removal of the Wastes as a Geologic Occurrance
Because the scale of impact along the Carson River is so large, natural detoxification will occur over the eons by subsequent sedimentation, dilution and diffusion. Man will have little or no effect to detoxifying the sediments along the Carson River because the job would prove insurmountable. The presence of toxic wastes will certainly be recorded in the accumulation of sediments at the river's termination at the Carson Sink. Future geologists 100,000 years from now will find a curious sand and clay layer rich in gold silver, mercury, arsenic and other elements which was derived from the Comstock. This layer will have a sharp basal contact and will defuse upwards into normal sedimentation sequences. Indeed, the Carson Sink is the ultimate tailings pond for the Comstock. Ironically this is also the site of an amazing population of both migrating and non-migrating water fowl.
Modern Regulation
Within the United States such mining practices as described above have been regulated into the history books so they are no longer practiced. Unfortunately, the legacy of such activity will be with us for generations to come. Today, modern mining practices in the United States include waste detoxification and disposal. It took early environmental disasters such as that which occurred along the Carson and at other localities to create mining reform that closely regulates and enforces strict compliance to high standards of mine waste disposal and treatment within all states of the union.
Environment and Use of Resources
It is this author's opinion that prudent mining practices must adhere to reasonable and sound regulation to provide the best blend of environmentalism and economic exploitation. Indeed, the two philosophies seem to be polar opposites. But as long as humans continue to use natural resources there will be a need for environmental regulation and the safeguards they provide.
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