Mercury contamination in California waterwaysposes a threat to both the environment and human health. This naturally occurring heavy metal may be released into the environment from natural geological sources, but most commonly occurs from anthropogenic mining operations. This metal poses a threat not only for its effects on organisms, but also for difficulty of removal from waterways and the trouble in efficiently detecting it. The roots of mercury poisoning in waterways began with the historic mining of gold within California's streambed and hillsides; since the California Gold Rush, mercury has been used for gold extraction for its ability as a catalyze with the precious metal. due to the process of extraction and washing, mercury used would either be burned away as a hazardous vapor, or washed away into waterflows, resulting in widespread contamination of river and lake sediments. mercury continues to be released today through anthropogenic sources, though state and federal agencies work to manage and ban these practices and to mitigate its effect on the environmental and on people. Many water bodies in the state of California bear fish consumption advisories due to mercury content.
Historical start of mercury pollution in California
Monitors (water canons) in the placer mines used to break down sediment for gold exposure.
Historically the Gold rush represents the beginning of mercury pollution in California's waterways, as well as a plethora of water related issues. The California Gold Rush can be traced to James Marshall's January 24, 1848 discovery of gold on John Sutter's property.[1] Marshall was a carpenter who helped construct the Sutter saw mill for Sutter, and the night before the iconic gold discovery Marshall diverted water from the American River through the lumber mill he was constructing tailrace to wash away loose gravel and dirt. The next morning (January 24, 1848) he discovered metallic flecks where the river water was flowing through the saw mill. He thought it was gold immediately, but didn't pursue it until the Sutter sawmill was completed.[1]
By the time of the following spring Marshall's gold discovery, the largest Gold Rush in American history began. In this short year the non-Native American population raised from 14,000 to 100,000.[1] The population increased again to 250,000 by the year of 1892.[1]
while initially easily extracted from the river sediments through by scooping and silling the river soil and gravel. The bottom trawler method was also developed to extract more gold at once. As the amount of miners and rate of mining increased, easily collected placer gold became scarcer, and new mining techniques were developed to extract gold more efficiently from rivers and the harder to reach lode gold.[2] One of the main, and also most destructive methods was that of hydraulic mining. This involved the redirecting of water from the river into a narrow channel, into a large canvas hose, and iron nozzle. Then these water cannons which were called monitors it would shoot a very high pressure stream that would break apart hillsides. The water, slurry, and debris, mostly gravel would flow over large sluices and drainage tunnels.[3] One of the most useful tools for increasing gold collection was the use of mercury, which prompted the mass use and mining of mercury in response.
Use of mercury in gold mining
Historically mercury, otherwise called "quicksilver" was used during the mining process.[2] During hydraulic mining when the water, slurry, and debris flowed over the sluices and drainage tunnels, the particles were also mixed with liquid mercury.[3] The mercury was used during the extraction period during the mining process. The mercury was used to attract the gold and sometimes silver from the mining ore, for extraction.[4] The most common use of mercury for the extraction was a process called mercury amalgamation.
The way that this process works is that the miner mixes the element mercury with mining silt or ore, the mercury then sticks to the gold, thus separating from the ore and silt, forming one solid piece of mercury–gold amalgam.[5] Additional separation from the silt and ore is done by washing away the ore with water until only the amalgam is left. The next step of the process is to separate the actual gold from the now useless mercury. The way this is done, is the miners heat up the mercury-gold amalgam to high temperature to vaporize the mercury away, leaving only the highly desired gold.[5] The vaporization of mercury requires a temperature of at least 357°C.[6] In addition to the mercury-gold amalgam some residue mercury is also still present in the silt and ore that was washed away, sometimes referred to as mine tailings. When these mine tailings are disposed of and during the washing process, large amounts of the remaining mercury often pollutes and infiltrates the local ecosystems and especially waterways around and down steam from the mining sites.[3] There was a loss of 10-30% of the mercury used during the extraction process, per season, which resulted in highly contaminated sediments at and down stream from mining sites.[3] The highest mercury contamination levels are present and can be sourced back to the Placer area in California.[3] Much of the mercury for mining was produced from deposits on the West side of California's central valley by the coast range, and it is estimated that 220,000,000 lb of mercury was procured from these deposits between 1850 and 1981.[7]
Primary sources of mercury
A large portion of currently known mercury contamination in California's waterways are the fault of not only unregulated mining methods of the gold rush, but also due to more modern mining practices of mining for mercury or gold. These sources of pollution are known as point sources (A localized and stationary pollution source), and often occur due to mercury being dispersed through mine tailings and wastewater during work, which infiltrates and brings mercury to water sources. While these point sources are the most visible of the pollutants, the mass majority of mercury contamination in waterbodies occurs through the deposition of gaseous mercury from the atmosphere.[8] Mercury cycles around its environment naturally, and will cycle through periods of being vaporized and deposited back onto water or land from the atmosphere. Mercury may also be cycled more easily throughout the environment through the action of anaerobic sulfur-processing bacteria found in water. Mercury in its organic form will build up in biota (organisms like fish or plants) and through natural processes will eventually be contained within organisms which die and decompose, locking mercury into the sediment of waterbodies.[9] Mercury naturally cycles itself in this manner, but the human release of vaporous mercury through gold and mercury industries has greatly increased the amount available in the environment, creating far more organic mercury pollution than is natural for our environment.
Mercury additionally may be released in large quantities into waterways through natural geothermal means. The sediment samples taken from Clear Lake was found to have a high amount of mercury concentration, which was believed to have come about from opening of geothermal fissures during seismic activity, which released a mass of stored mercury rich elements into the lake.[10] A sample core study of the lakebed sediments determined the amount of mercury released into the water to be around 2,400 tons.
Environmental impacts
Mercury caused birth and developmental deformities in waterfowl.
Mercury caused birth and developmental deformities in waterfowl.
When mercury first enters into waterways and ecosystems, it is considered elemental inorganic mercury. While this heavy metal is highly toxic in its elemental form, it can become more-so through it being manipulated into a biologically accessible form known as methylmercury. While the full process of how the methylation process and trophic magnification function or vary in different circumstances is not fully understood, it is known that bacteria play a primary role in mercury's inclusion into the ecosystem by absorbing elemental mercury, methylating it into an organically accessible form, and either releasing the methylmercury into the environment where it is absorbed by plankton, or by being consumed by another organism that feeds on the bacteria.[11] These bacteria are known as anaerobic bacteria species, which convert elemental mercury into methylmercury by methylating oxidized mercury to methylmercury.[11]
This newly transformed form of mercury (methylmercury) then begins to bio-accumulate in the many species inhabiting the contaminated waterways and ecosystems.[5] Many plants and autotrophic organism passively absorb Methylmercury throughout their life, and even under long-term exposure with methylmercury, their fitness is not significantly reduced.[12] Autotrophs like animals on the other hand accumulate methylmercury in their body's faster as they consume other mercury-containing organisms, resulting in the process of each successive level in the food chain consuming higher levels of methylmercury (Biomagnification). The bio-accumulation levels of toxic methylmercury are found to be the highest by larger predator fish species, fish eating animals, and humans for whom fish is a prominent food source.[13] Though methylmercury traces have also been found in reptiles, amphibians, invertebrates, flora, birds, and even the surrounding soil.[3]
The environments that methylmercury levels are most commonly found in at high levels are wetlands, newly flooded reservoirs, aquatic areas close to mining sites or factories, bays, and waterways with low pH levels, as this is strongly correlated with rate of bacteria methylmercury production. mercury release sites from anthropomorphic and natural sources can pollute waterways for great distances should they be uphill of a watershed.[13]
The many health effects of methylmercury has on wildlife include reproductive problems and reductions, enzyme and immune system problems, developmental issues, and genetic alterations.[13] These problems have had the greatest effects on waterfowl because of their high fish diets. Some of the waterfowl experiencing the most problems with methylmercury are the Great Egret, Diving Duck, Herons, and Loons. Research and scientific surveys have shown a dramatic reduction in Loon chicks and a change in juvenile Great Egrets with a direct correlation with high levels of methylmercury.[13] Ecosystems with both methylmercury and the element selenium can produce an even more toxic and potentially deadly mixture for wildlife.[13]
Human health impacts
Areas in California with fish consumption advisories due to mercury contamination.
There have been many studies and negative health impacts, directly relating to mercury contamination in both food sources and the environment. One of the main sources of mercury contamination and over consumption is through fish, already contaminated with high levels of mercury. Mercury can impair, damage, and even destroy functioning nerve tissue-much like lead.[15] The over consumption of methylmercury can also reduce immune system response, damage the nervous system, including coordination, sense of touch, taste, and sight.[13]
One of the major health threats presented from the over consumption of these high mercury levels is the development of learning disabilities and developmental problems in children. This is the result of over mercury exposure after birth, and/or over consumption of high mercury levels of the mother during pregnancy. The high concern is because mercury can be passed between the pregnant mother through the placenta to the unborn fetus.[15] The form that mercury that is being consumed is Methylmercury, which the federal government has classified as a neurotoxin, which is described as a poisonous substance that attacks the nervous system, and impairs the function of the nerve and nerve tissue.[16] Even small amounts of this neurotoxin can cause brain and nervous system development problems. The effects of this utero (before birth in the uterus)[16] transfer can also take between a number of months or even years before signs appear, making it difficult to trace back. The forms that methylmercury exposure will show itself is that the child will have shorter attention spans, poor fine motor skills, slow language development, visual-spatial abilities (like drawing), and memory.[15] A mothers exposure and consumption of methylmercury prior to pregnancy can also be just as serious as exposure during pregnancy, because methylmercury is slowly excreted from the body, sometimes taking months to fully leave an individual's system. This can greatly effect the fetuses development, as many important developmental stages of the nervous systems and brain occur during the first two months of pregnancy. Health experts suspect that children are more susceptible to methylmercury than adults, because they eat more food relative to their total body weight causing a higher contamination percentage.[15] It has been concluded that 60,000 children born each year are at risk for neuro-developmental effects, due to in utero exposure to methylmercury.[13]
Another form of human exposure to elemental mercury is the inhalation of the vaporized form of the element directly from its source in the environment. This form of exposure is especially common in and around old mining sites.[13] This form of exposure can cause gingivitis, tremors, damages to the gastrointestinal tract, less efficient enzyme productivity, and in rare cases kidney failure.[13]
Removal from water
There have been many studies on the purification and extraction of mercury from water sources and sometimes even the affected soils around the contaminated water sources. Some of these methods that are continuously being researched and sampled are the use of high-performance liquid chromatography (HPLC) combined with inductively-coupled plasma mass spectrometry (ICP-MS).[17] Because the different forms of mercury have different forms of toxicity, this method allows for the removal of each form and a thorough study of the toxicity and potential harm of each separate form. This is because the typical concentration of methylmercury in water sources and Methylmercury is below detection rates, but it doesn't necessarily mean the continuous buildup in the consumers body's, or the environment will have any symptoms. The most common method of speciation for the removal, is gas chromatography or high-pressure liquid chromatography paired with fluorescence, natural elements, and photometry detectors.[17] The downside of this form of detection is that it requires very large numbers of samples to test the concentration and toxicity levels. Other methods include the charging of ions to separate the toxic elements and toxins from the water for extraction. These methods are currently most common for use in China, for the removal of these toxic heavy metals for the use of drinking water.[17] One theory that is being tested by the federal government to clean methylmercury out of waterways, is to find a bacterium that transforms methylmercury back into elemental mercury. With this process of transformation, the elemental mercury can vaporize and evaporate out of the waterways naturally.[11]
Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance faster than it can be lost or eliminated by catabolism and excretion. Thus, the longer the biological half-life of a toxic substance, the greater the risk of chronic poisoning, even if environmental levels of the toxin are not very high. Bioaccumulation, for example in fish, can be predicted by models. Hypothesis for molecular size cutoff criteria for use as bioaccumulation potential indicators are not supported by data. Biotransformation can strongly modify bioaccumulation of chemicals in an organism.
Mercury poisoning is a type of metal poisoning due to exposure to mercury. Symptoms depend upon the type, dose, method, and duration of exposure. They may include muscle weakness, poor coordination, numbness in the hands and feet, skin rashes, anxiety, memory problems, trouble speaking, trouble hearing, or trouble seeing. High-level exposure to methylmercury is known as Minamata disease. Methylmercury exposure in children may result in acrodynia in which the skin becomes pink and peels. Long-term complications may include kidney problems and decreased intelligence. The effects of long-term low-dose exposure to methylmercury are unclear.
The Gunnison River is located in western Colorado, United States and is one of the largest tributaries of the Colorado River.
The Carson River is a northwestern Nevada river that empties into the Carson Sink, an endorheic basin. The main stem of the river is 131 miles (211 km) long although the addition of the East Fork makes the total length 205 miles (330 km), traversing five counties: Alpine County in California and Douglas, Storey, Lyon, and Churchill Counties in Nevada, as well as the Consolidated Municipality of Carson City, Nevada. The river is named for Kit Carson, who guided John C. Frémont's expedition westward up the Carson Valley and across Carson Pass in winter, 1844. The river made the National Priorities List (NPL) on October 30, 1990 as the Carson River Mercury Superfund site (CRMS) due to investigations that showed trace amounts of mercury in the wildlife and watershed sediments.
Methylmercury (sometimes methyl mercury) is an organometallic cation with the formula [CH3Hg]+. It is the simplest organomercury compound. Methylmercury is extremely toxic, and its derivatives are the major source of organic mercury for humans. It is a bioaccumulative environmental toxicant with a 50-day half-life.
Gold extraction is the extraction of gold from dilute ores using a combination of chemical processes. Gold mining produces about 3600 tons annually, and another 300 tons is produced from recycling.
Environmental toxicants and fetal development is the impact of different toxic substances from the environment on the development of the fetus. This article deals with potential adverse effects of environmental toxicants on the prenatal development of both the embryo or fetus, as well as pregnancy complications. The human embryo or fetus is relatively susceptible to impact from adverse conditions within the mother's environment. Substandard fetal conditions often cause various degrees of developmental delays, both physical and mental, for the growing baby. Although some variables do occur as a result of genetic conditions pertaining to the father, a great many are directly brought about from environmental toxins that the mother is exposed to.
Soil contamination, soil pollution, or land pollution as a part of land degradation is caused by the presence of xenobiotic (human-made) chemicals or other alteration in the natural soil environment. It is typically caused by industrial activity, agricultural chemicals or improper disposal of waste. The most common chemicals involved are petroleum hydrocarbons, polynuclear aromatic hydrocarbons, solvents, pesticides, lead, and other heavy metals. Contamination is correlated with the degree of industrialization and intensity of chemical substance. The concern over soil contamination stems primarily from health risks, from direct contact with the contaminated soil, vapour from the contaminants, or from secondary contamination of water supplies within and underlying the soil. Mapping of contaminated soil sites and the resulting clean ups are time-consuming and expensive tasks, and require expertise in geology, hydrology, chemistry, computer modelling, and GIS in Environmental Contamination, as well as an appreciation of the history of industrial chemistry.
Environmentally, Colombia is a mega-diverse country from its natural land terrain to its biological wildlife. Its biodiversity is a result of its geographical location and elevation. It is the fourth largest South American country and only country in South America to have coasts on the Pacific and Caribbean Sea. Colombia's terrain can be divided into six main natural zones: The Caribbean, the Pacific, The Orinoco region, The Amazonia region, the Andean region, and the Insular region. 52.2% of the environment is predominately the Andes, Amazon, and Pacific Basins, followed by the Orinoco basin 13.9%, the Andes and the Caribbean. The Tropical Andes, Choco, and the Caribbean are considered biodiversity hotspots which puts these areas at high risk of concentration of colonizing activities. Colombia host over 1800 bird species and at least one new species are detected every year. Decades of civil war and political unrest have impeded biological and environmental research in Colombia. The political unrest in Colombia catalyzes the alteration of land patterns through the cultivation of coca and opium crops, the redirection of extractive activities, and land abandonment in some areas.
The Guadalupe River watershed consists of 170 square miles (400 km2) of land within northern California's Santa Clara County. The surface runoff from this area drains into the Guadalupe River, its tributary streams, reservoirs or other bodies of water which all eventually gets carried into the San Francisco Bay. Essentially, all the water from the creeks and rivers that make up the Guadalupe watershed, including water from storm drains, flows into the Guadalupe River, and then flows downstream into the San Francisco Bay at the Alviso Slough in Alviso. The Guadalupe watershed's main tributaries include Los Gatos Creek, Trout Creek, Hendrys Creek, Ross Creek, Pheasant Creek, Rincon Creek, Herbert Creek, and Golf Creek. Six major reservoirs exist in the watershed: Calero Reservoir on Arroyo Calero, Guadalupe Reservoir on Guadalupe Creek, Almaden Reservoir on Los Alamitos Creek, Vasona Reservoir, Lexington Reservoir, and Lake Elsman on Los Gatos Creek.
Environmental toxicology is a multidisciplinary field of science concerned with the study of the harmful effects of various chemical, biological and physical agents on living organisms. Ecotoxicology is a subdiscipline of environmental toxicology concerned with studying the harmful effects of toxicants at the population and ecosystem levels.
The health and environmental impact of the coal industry includes issues such as land use, waste management, water and air pollution, caused by the coal mining, processing and the use of its products. In addition to atmospheric pollution, coal burning produces hundreds of millions of tons of solid waste products annually, including fly ash, bottom ash, and flue-gas desulfurization sludge, that contain mercury, uranium, thorium, arsenic, and other heavy metals. Coal is the largest contributor to the human-made increase of carbon dioxide in Earth's atmosphere.
Mercury is a chemical element; it has symbol Hg and atomic number 80. It is also known as quicksilver and was formerly named hydrargyrum from the Greek words hydor (water) and argyros (silver). A heavy, silvery d-block element, mercury is the only metallic element that is known to be liquid at standard temperature and pressure; the only other element that is liquid under these conditions is the halogen bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature.
The presence of mercury in fish is a health concern for people who eat them, especially for women who are or may become pregnant, nursing mothers, and young children. Fish and shellfish concentrate mercury in their bodies, often in the form of methylmercury, a highly toxic organomercury compound. This element is known to bioaccumulate in humans, so bioaccumulation in seafood carries over into human populations, where it can result in mercury poisoning. Mercury is dangerous to both natural ecosystems and humans because it is a metal known to be highly toxic, especially due to its neurotoxic ability to damage the central nervous system.
Freshwater environmental quality parameters are those chemical, physical or biological parameters that can be used to characterise a freshwater body. Because almost all water bodies are dynamic in their composition, the relevant quality parameters are typically expressed as a range of expected concentrations.
Environmental effects of mining can occur at local, regional, and global scales through direct and indirect mining practices. Mining can cause erosion, sinkholes, loss of biodiversity, or the contamination of soil, groundwater, and surface water by chemicals emitted from mining processes. These processes also affect the atmosphere through carbon emissions which contributes to climate change. Some mining methods may have such significant environmental and public health effects that mining companies in some countries are required to follow strict environmental and rehabilitation codes to ensure that the mined area returns to its original state.
Mercury regulation in the United States limit the maximum concentrations of mercury (Hg) that is permitted in air, water, soil, food and drugs. The regulations are promulgated by agencies such as the Environmental Protection Agency (EPA) and Food and Drug Administration (FDA), as well as a variety of state and local authorities. EPA published the Mercury and Air Toxics Standards (MATS) regulation in 2012; the first federal standards requiring power plants to limit emissions of mercury and other toxic gases.
Mercury is a heavy metal that cycles through the atmosphere, water, and soil in various forms to different parts of the world. Due to this natural mercury cycle, irrespective of which part of the world releases mercury it could affect an entirely different part of the world making mercury pollution a global concern. Mercury pollution is now identified as a global problem and awareness has been raised on an international action plan to minimize anthropogenic mercury emissions and clean up mercury pollution. The 2002 Global Mercury Assessment concluded that "International actions to address the global mercury problem should not be delayed". Among many environments that are under the impact of mercury pollution, the ocean is one which cannot be neglected as it has the ability to act as a "storage closet" for mercury. According to a recent model study the total anthropogenic mercury released into the ocean is estimated to be around 80,000 to 45,000 metric tons and two-thirds of this amount is estimated to be found in waters shallower than 1000m level where much consumable fish live. Mercury can bioaccumulate in marine food chains in the form of highly toxic methylmercury which can cause health risks to human seafood consumers. According to statistics, about 66% of global fish consumption comes from the ocean. Therefore, it is important to monitor and regulate oceanic mercury levels to prevent more and more mercury from reaching the human population through seafood consumption.
Mercury is a poisonous element found in various forms in Canada. It can be emitted in the atmosphere naturally and anthropogenically, the main cause of mercury emission in the environment. Mercury pollution has become a sensitive issue in Canada for the past few decades and many steps have been taken for prevention at local, national, and international levels. It has been found to have various negative health and environmental effects. Methylmercury is the most toxic form of mercury which is easily accessible as well as digestible by living organisms and it is this form of mercury causing serious harm to human and wildlife health.
Mercury contamination in Grassy Narrows was an uncontrolled discharge of between 9,000 kilograms (20,000 lb) and 11,000 kilograms (24,000 lb) of mercury from the Dryden Mill's chloralkali plant in Dryden into the headwaters of the Wabigoon River in the Kenora District of Northwestern Ontario from 1962 until 1970. It was described as "one of the worst cases of environmental poisoning in Canadian history." The contamination poisoned many people in the Grassy Narrows First Nation and Whitedog First Nation communities
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