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Communal Cultural center construction by the Maya
Aresnic
As with other arsenic compounds, arsenite binds to lipoic acid,[3] inhibiting the conversion of pyruvate into acetyl-CoA, blocking the Krebs cycle and therefore resulting in further loss of ATP.
Well contains AS III
and is converted to
Another effective and inexpensive method to avoid arsenic contamination is to sink wells 500 feet or deeper to reach purer waters. A recent 2011 study funded by the US National Institute of Environmental Health Sciences' Superfund Research Program shows that deep sediments can remove arsenic and take it out of circulation. In this process, called adsorption, arsenic sticks to the surfaces of deep sediment particles and is naturally removed from the ground water.[130]
Arsenic Owners of private wells are responsible for ensuring that their water is safe from contaminants. The presence of contaminants in water can lead to health issues, including gastrointestinal illness, reproductive problems, and neurological disorders. What is arsenic? Arsenic is a naturally occurring mineral found in soil and bedrock and enters the groundwater through erosion. Arsenic can be present in well water as Arsenic III (arsenite), Arsenic V (arsenate), or a combination of the two. Arsenic III is more toxic and more common in groundwater than Arsenic V. Where and how does arsenic get into drinking water? Arsenic occurs naturally in rocks, soil, water, air, and plants and animals. It can be further released into the environment through natural activities such as volcanic action, erosion of rocks and forest fires, or through human actions. The demand on groundwater from drinking water wells may cause water levels to drop and release arsenic from rock formations. What are the health effects? Health effects from arsenic exposure include skin damage, diabetes, circulatory system problems and an increased cancer risk, including cancers of the skin, bladder, lungs, kidneys, nasal passages, liver and prostate. Early warning signs may include stomach pain, nausea, vomiting, diarrhea, and numbness in the extremities. How can I find out whether there is arsenic in my drinking water? Arsenic has no smell, taste, or color when dissolved in water, even in high concentrations, and therefore only laboratory analysis can determine the presence and concentration of arsenic in water. If there is arsenic in your water, a laboratory can determine how much and which type(s) of arsenic is present, through a method called "speciation." This is important because treatment methods vary for each type. You may also test for other contaminants, including iron and manganese, because the presence of these contaminants may hinder the effectiveness of arsenic removal and will need to be removed before treatment. As the well owner, you are responsible for sampling and testing your drinking water. DEQ has compiled a list of laboratories in the state for your convenience. How do I remove arsenic from my drinking water? There are typically two species of arsenic in water, arsenic 3 and arsenic 5. Arsenic 3 is difficult to remove from water and must be changed or oxidized to arsenic 5 before it can be removed. Oxidants that can convert arsenic 3 to arsenic 5 include liquid chlorine (bleach), hydrogen peroxide, and ozone. Chlorine is the most readily available oxidant for home water treatment. Since arsenic poses an ingestion risk, the water that is ingested mainly needs to be treated. Point of use devices like activated alumina or reverse osmosis have proven to be effective for removing arsenic. In most cases, the device is plumbed in at the kitchen sink and treats only the water intended solely for consumption.
At pH 6.5 to 8.5, As III is present as uncharged arsenious acid, H3AsO3, under reducing conditions, whereas As V is present in the form of singly and doubly charged H2AsO4- and HAsO42- anions in oxidizing waters. Thus, processes that remove anions (e.g., anion exchange and activated alumina adsorption) are suitable for removing As V but not As III. Other small system processes that are suitable for removing As V anions are iron coagulation followed by multimedia filtration or microfiltration. Iron-oxide-based adsorbents such as granular ferric hydroxide (GFH) and iron-doped filtration as well as adsorption media also are effective. Reverse osmosis does a better job of removing As V compared with As III, and electrodialysis will remove As V but will not remove any As III. When examining all these treatment possibilities, it is apparent that As III, when present, must be oxidized to As V for efficient removal.
• Ozone was extremely effective at As III oxidation; complete oxidation was achieved in less than 15 seconds. No adverse effect was observed in the presence of either dissolved manganese or dissolved iron, but sulfide slowed As III oxidation considerably.
• Surprisingly, chlorine dioxide was not effective for As III oxidation. A three-fold stoichiometric dose of chlorine dioxide produced only 20 to 30 percent oxidation in 21 seconds and none thereafter. Even a 100-times stoichiometric dose produced only 76 percent oxidation in five minutes.