Lexikon

many different methods and combinations of techniques can be used to apply heat to polluted soil and/or groundwater in situ. The heat can destroy or volatilize organic chemicals. As the chemicals change into gases, their mobility increases, and the gases can be extracted via collection wells for capture and cleanup in an ex situ treatment unit. Thermal methods can be particularly useful for dense or light nonaqueous phase liquids (DNAPLs or LNAPLs). Heat can be introduced to the subsurface by electrical resistance heating, radio frequency heating, dynamic underground stripping, thermal conduction, or injection of hot water, hot air, or steam.

The main advantage of in situ thermal methods is that they allow soil to be treated without being excavated and transported, resulting in significant cost savings; however, in situ treatment generally requires longer time periods than ex situ treatment, and there is less certainty about the uniformity of treatment because of the variability in soil and aquifer characteristics and because the efficacy of the process is more difficult to verify.

ELECTRICAL RESISTANCE HEATING uses arrays of electrodes installed around a central neutral electrode to create a concentrated flow of current toward the central point. Resistance to flow in the soils generates heat greater than 100ºC, producing steam and readily mobile contaminants that are recovered via vacuum extraction and processed at the surface. Electrical resistance heating is an extremely rapid form of remediation with case studies of effective treatment of soil and groundwater in less than 40 days. Three-phase heating and six-phase soil heating are varieties of this technology.

INJECTION OF HOT AIR can volatilize organic contaminants (e.g., fuel hydrocarbons) in soils or sediments. With deeper subsurface applications, hot air is introduced at high pressure through wells or soil fractures. In surface soils, hot air is usually applied in combination with soil mixing or tilling, either in situ or ex situ.

INJECTION OF HOT WATER via injection wells heats the soil and ground water and enhances contaminant release. Hot water injection also displaces fluids (including LNAPL and DNAPL free product) and decreases contaminant viscosity in the subsurface to accelerate remediation through enhanced recovery.

INJECTION OF STEAM heats the soil and groundwater and enhances the release of contaminants from the soil matrix by decreasing viscosity and accelerating volatilization. Steam injection may also destroy some contaminants. As steam is injected through a series of wells within and around a source area, the steam zone grows radially around each injection well. The steam front drives the contamination to a system of ground-water pumping wells in the saturated zone and soil vapor extraction wells in the vadose zone.

RADIO FREQUENCY HEATING is an in situ process that uses electromagnetic energy to heat soil and enhance soil vapor extraction. The technique heats a discrete volume of soil using rows of vertical electrodes embedded in soil or other media. Heated soil volumes are bounded by two rows of ground electrodes with energy applied to a third row midway between the ground rows. The three rows act as a buried triplate capacitor. When energy is applied to the electrode array, heating begins at the top center and proceeds vertically downward and laterally outward through the soil volume. The technique can heat soils to over 300ºC.

THERMAL CONDUCTION (also referred to as electrical conductive heating or in situ thermal desorption) supplies heat to the soil through steel wells or with a blanket that covers the ground surface. As the polluted area is heated, the contaminants are destroyed or evaporated. Steel wells are used when the polluted soil is deep. The blanket is used where the polluted soil is shallow. Typically, a carrier gas or vacuum system transports the volatilized water and organics to a treatment system.

VITRIFICATION uses an electric current to melt contaminated soil at elevated temperatures (1,600 to 2,000ºC or 2,900 to 3,650ºF). Upon cooling, the vitrification product is a chemically stable, leach-resistant, glass and crystalline material similar to obsidian or basalt rock. The high temperature component of the process destroys or removes organic materials. Radionuclides and heavy metals are retained within the vitrified product. Vitrification can be conducted in situ or ex situ.

Source: US-EPA, Clu-In: http://www.clu-in.org/techfocus/default.focus/sec/Thermal_Treatment%3A_In_Situ/cat/Overview/

the Institute for Health and Consumer Protection (IHCP) is one of the seven scientific institutes of the Joint Research Centre (JRC), of the European Commission. Its mission is to protect the interests and health of the consumer in the framework of EU legislation on chemicals, food and consumer products.

IHCP co-operates a number of policy domains which are relevant to consumer protection and health of European citizens. The most relevant areas are:

• Alternative Methods and ECVAM (European Centre for the Validation of Alternative Methods)
• GMOs
• Nanotechnology
• Consumer Products and Nutrition
• Health and Environment

In some of these areas IHCP operates Community Reference Laboratories or offices which coordinate a particular activity in collaboration with national laboratories in the European Union Member States. The two Community Reference Laboratories (CRL) are:

1. The Community Reference Laboratory on Food Contact Materials (CRL-FCM) and
2. The Community Reference Laboratory for GM Food and Feed (CRL-GMFF)

And the centres/officea are:

1. The European Centre for Validation of Alternative Methods (ECVAM)
2. The European Office for Wine, Alcoholic and Spirit Drinks (BEVABS)

Source: http://ihcp.jrc.ec.europa.eu/

noise occurring at regular or irregular intervals.

subterranean water in the pores of rocks, soils, and bottom sediments of oceans, seas, and lakes.

Two types of interstitial water are distinguished, according to the size of the enclosing interstices: macrocapillary and microcapillary. In interconnected macrocapillary pores, interstitial water moves easily by force of gravity; this is called free, or gravitational, water. Interstitial water in microcapillary pores, is influenced by the surface forces of mineral particles; it has the properties of bound water, which is separated by pressing out, centrifuging, or drawing out under a vacuum.

In the late 1960’s the term “interstitial water” came to be used primarily for water enclosed in microcapillaries; in marine geology this water is also called silt water. The water is present in all rocks and bottom sediments, but it is especially characteristic of clay rocks and sediments. Geological reserves of this water are significantly greater than reserves of free water. The interstitial water of the microcapillary pores is the medium in which the processes determining the mass exchange between hydrous and solid phases of rocks and sediments occur most intensively. For this reason, interstitial water is important in the history of subsurface water, the diagenesis of sediments, and the catagenesis of rocks. It affects the strength and behavior of rocks when engineering structures are erected.

Information Technology

Local Area Network

Liquid Crystal Display)

abbreviated as LOD, defined as the lowest concentration or quantity of analyte required to give a signal, which can be distinguished from the background noise. The signal to noise ratio of 3:1 is generally considered acceptable for estimating LOD.

limit of quantification (LOQ) is the lowest concentration, which can be determined with acceptable precision and accuracy. For determination of LOQ the precision and accuracy should be also quantified. It can be calculated from the standard deviation of the blank measurement and the slope of the calibration curve. Usually the LOQ is given as 10 times the background noise.

in the Earth, the lithosphere includes the crust and the uppermost mantle, which constitute the hard and rigid outer layer of the Earth. The lithosphere is underlain by the asthenosphere, the weaker, hotter, and deeper part of the upper mantle. The boundary between the lithosphere and the underlying asthenosphere is defined by a difference in response to stress: the lithosphere remains rigid for very long periods of geologic time in which it deforms elastically and through brittle failure, while the asthenosphere deforms viscously and accommodates strain through plastic deformation. There are two types of lithosphere: 1) oceanic lithosphere, which is associated with oceanic crust and exists in the ocean basins, 2) continental lithosphere, which is associated with continental crust. The composition of the two types of crust differs markedly, with basaltic rocks ("mafic") dominating oceanic crust, while continental crust consists principally of lower density granitic rocks ("felsic"). The lithosphere is broken into tectonic plates. The following tectonic plates currently exist on the earth's surface with roughly definable boundaries. There are seven primary plates (African Plate, Antarctic Plate, Eurasian Plate, Indo-Australian Plate, North American Plate, Pacific Plate, South American Plate) and some secondary smaller plates (Arabian-, Caribbean-, Cocos-, Scotia-, Adria-, Aegean-, Arab-, Iranian-, Nazca-, Philippine Sea -plates).These plates are rigid segments that move in relation to one another at one of three types of plate boundaries: 1) convergent boundaries, at which two plates come together, (an example of such a boundary is the San Andreas fault in California) 2) divergent boundaries, at which two plates are pulled apart (the Atlantic Ocean was created by this process, the mid-Atlantic Ridge is an area where new sea floor is being created), and 3) transform boundaries, in which two plates slide past one another laterally. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation can occur along these plate boundaries. The tectonic plates ride on top of the asthenosphere, the solid but less-viscous part of the upper mantle that can flow and move along with the plates, and their motion is strongly coupled with patterns convection inside the Earth's mantle. An example of this is the Nazca plate being subducted under the South American plate to form the Andes Mountain Chain.

unit of volume. Its conversion to other units:

mega-sites are large scale contaminated sites, which pose a large potential or an actual risk of deterioration to groundwater, sediment, soil and surface-water quality. These expensive sites such as mine sites and asbestos sites, require complicated and costly remediation. They are extremely complicated cleanups that are resource intensive, have different sources, and can take years to remediate. (Source: EUGRIS)

the genetic material found in mitochondria, the organelles that generate energy for the cell.

The mitochondrion has its own independent genome. Not inherited in the same fashion as nucleic DNA and the molecular structure is also different from the chromosomal DNA.

Further, its DNA shows substantial similarity to bacterial genomes. Based on this similarity they are thought to be originally derived from endosymbiotic prokaryotes.

mitosis is the process of nuclear division in cells that produces daughter cells that are genetically identical to each other and to the parent cell.

Monitored Natural Attenuation (MNA) is the monitoring of the effects of naturally occurring physical, chemical, and biological processes or any combination of these processes to reduce the load, concentration, flux or toxicity of polluting substances in soil and groundwater in order to obtain a sustainable remediation objective.

Moving Picture Experts Group, department of ISO

mutagenic substances or agents are, those, which induce mutation in living cells. Mutagenicity refers to the induction of permanent transmissible changes in the amount or structure of the genetic material of cells or organisms. These changes may involve a single gene or gene segment, a block of genes or chromosomes.

Alterations to the genetic material of cells may occur spontaneously or be induced as a result of exposure to ionising or ultraviolet radiation, or genotoxic substances. In principle, human exposure to substances that are mutagens may result in increased frequencies of mutations above baseline. Heritable damage to the offspring, and possibly to subsequent generations, of parents exposed to substances that are mutagens may follow if mutations are induced in parental germ cells (reproduction cells). Mutations in somatic cells (cells others than reproduction cells) may be lethal or may be transferred to daughter cells with deleterious consequences for the affected organism. There is considerable evidence of a positive correlation between the mutagenicity of substances in vivo and their carcinogenicity in long-term studies with animals. The aims of testing for mutagenicity are to assess the potential of substances to induce effects which may cause heritable damage in humans or lead to cancer.

Mutagens are usually chemical compounds or ionizing radiation. Mutagens can be divided into different categories according to their effect on DNA replication:

• Some mutagens act as base analogs and get inserted into the DNA strand during replication in place of the substrates.
• Some react with DNA and cause structural changes that lead to miscopying of the template strand when the DNA is replicated.
• Some work indirectly by causing the cells to synthesize chemicals that have the direct mutagenic effect.

mutagenicity refers to the induction of permanent transmissible changes in the amount or structure of the genetic material of cells or organisms. These changes may involve a single gene or gene segment, a block of genes or chromosomes.
Alterations to the genetic material of cells may occur spontaneously or be induced as a result of exposure to ionising or ultraviolet radiation, or genotoxic substances. In principle, human exposure to substances that are mutagens may result in increased frequencies of mutations above baseline. Heritable damage to the offspring, and possibly to subsequent generations, of parents exposed to substances that are mutagens may follow if mutations are induced in parental germ cells (reproduction cells). Mutations in somatic cells (cells others than reproduction cells) may be lethal or may be transferred to daughter cells with deleterious consequences for the affected organism. There is considerable evidence of a positive correlation between the mutagenicity of substances in vivo and their carcinogenicity in long-term studies with animals. The aims of testing for mutagenicity are to assess the potential of substances to induce effects which may cause heritable damage in humans or lead to cancer.

Chemicals are defined as carcinogenic if they induce tumours, increase tumour incidence and/or malignancy or shorten the time to tumour occurrence. Carcinogenic chemicals have conventionally been divided into two categories according to the presumed mode of action. Non-genotoxic modes of action include epigenetic changes, i.e., effects that do not involve alterations in DNA but that may influence gene expression, altered cell-cell communication, or other factors involved in the carcinogenic process. The objective of investigating the carcinogenicity of chemicals is to identify potential human carcinogens, their mode(s) of action, and their potency.
Once a chemical has been identified as a carcinogen, there is a need to elucidate the underlying mode of action, i.e. whether the chemical is directly genotoxic or not. For genotoxic carcinogens it is assumed that, unless exception, there is no discernible threshold and that any level of exposure carries a risk. For non-genotoxic carcinogens, no-effect-thresholds are assumed to exist and to be discernable. Human studies are generally not available for making a distinction between the above mentioned modes of action; and a conclusion on this, in fact, depends on the outcome of mutagenicity testing and other mechanistic studies. In addition to this, animal studies may also inform on the underlying mode of carcinogenic action.
The cancer hazard and mode of action may also be highly dependent on exposure conditions such as the route of exposure. Therefore, all relevant effect data and information on human exposure conditions are evaluated.

Source: REACH