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All over the world, aquatic sediments and soils are being contaminated by a vast array of agents: BTEX, petroleum, diesel, polycyclic aromatic hydrocarbons (PAHs) and other semi-volatile organic compounds. Sediment remediation is the technology used to neutralize contaminants and restore ecosystems to the state they were in before the contaminants were introduced. The choice of technology used in a particular instance is a factor of the amount of money that is available to the project and the timespan within which the decontamination needs to occur. The main factor driving the decision is the nature of the contaminant.
When the sediments and soils beneath aquatic environments such as harbors and rivers becomes contaminated, their recreational and navigational use can be seriously compromised. By 2004, the Environmental Protection Agency (EPA) had identified approximately 12 dozen sites that needed attention. Of these, nearly half (60) were deemed sufficiently important to merit tracking at the national level; others were considered suitable for attention at the local level.
There are three major approaches to managing contaminated sediment. These are dredging, monitored natural recovery and in situ capping. Among the major sources of soil contamination are mining, industrial accidents. In addition to the contaminants listed above, others include pesticides (DDT), Phthalate Esters, metals (lead and mercury), organometals, cyanide, Mononuclear Aromatic Hydrocarbons (MAHs) and chlorinated hydrocarbons (PCBs).
Some of these substances are either completely insoluble or only partially soluble in aqueous solvents and end up becoming embedded in aquatic sedimentation. This means these poisons are indetectable in the water column. The organic content of these particles, their size and shape, and the ecology of benthic oranisms (bottom feeders) all promote the steady accumulation of contaminated sediments.
Once a government agency identifies a site to be remediated, prompt action is essential in order to protect human health as well as the environment. All remediation projects require regulatory oversight. In the USA, this is provided by the Region 9 of the EPA.
Nanotechnology, the process of using particles between 1 and 100 nanometers, is becoming more and more important in aquatic soil remediation. Their high surface area per unit mass makes them extremely reactive; their miniscule size makes it easy for them to infiltrate micropores in the sediments, which gives them ready access to the target materials. A nanometer is one billionth of a meter.
When a nanoparticle-sized decontaminant collides with a target contaminant, the result is a neutralizing chemical reaction. So far, the global NanoRem project has targeted as many as 70 sites all over the world that need to be treated. Most of these are groundwater projects, although wastewater treatment methods are being investigated.
What makes nanoremediation fascinating is the scale of the contaminants being removed. It is easy to filter out particles on the micrometer level (one millionth of a meter); nanoparticles are more challenging. Onced the nanoremediation technology has been perfected, perhaps man can start developing technologies to tackle pico particles, which are one thousandth the size of a nanometer.
When the sediments and soils beneath aquatic environments such as harbors and rivers becomes contaminated, their recreational and navigational use can be seriously compromised. By 2004, the Environmental Protection Agency (EPA) had identified approximately 12 dozen sites that needed attention. Of these, nearly half (60) were deemed sufficiently important to merit tracking at the national level; others were considered suitable for attention at the local level.
There are three major approaches to managing contaminated sediment. These are dredging, monitored natural recovery and in situ capping. Among the major sources of soil contamination are mining, industrial accidents. In addition to the contaminants listed above, others include pesticides (DDT), Phthalate Esters, metals (lead and mercury), organometals, cyanide, Mononuclear Aromatic Hydrocarbons (MAHs) and chlorinated hydrocarbons (PCBs).
Some of these substances are either completely insoluble or only partially soluble in aqueous solvents and end up becoming embedded in aquatic sedimentation. This means these poisons are indetectable in the water column. The organic content of these particles, their size and shape, and the ecology of benthic oranisms (bottom feeders) all promote the steady accumulation of contaminated sediments.
Once a government agency identifies a site to be remediated, prompt action is essential in order to protect human health as well as the environment. All remediation projects require regulatory oversight. In the USA, this is provided by the Region 9 of the EPA.
Nanotechnology, the process of using particles between 1 and 100 nanometers, is becoming more and more important in aquatic soil remediation. Their high surface area per unit mass makes them extremely reactive; their miniscule size makes it easy for them to infiltrate micropores in the sediments, which gives them ready access to the target materials. A nanometer is one billionth of a meter.
When a nanoparticle-sized decontaminant collides with a target contaminant, the result is a neutralizing chemical reaction. So far, the global NanoRem project has targeted as many as 70 sites all over the world that need to be treated. Most of these are groundwater projects, although wastewater treatment methods are being investigated.
What makes nanoremediation fascinating is the scale of the contaminants being removed. It is easy to filter out particles on the micrometer level (one millionth of a meter); nanoparticles are more challenging. Onced the nanoremediation technology has been perfected, perhaps man can start developing technologies to tackle pico particles, which are one thousandth the size of a nanometer.
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