Lexikon
a permeable reactive barrier (PRB) is defined as an in situ method for remediating contaminated ground water that combines a passive chemical or biological treatment zone with subsurface fluid flow management. Treatment media may include zero-valent iron, chelators, sorbents, and microbes to address a wide variety of ground-water contaminants, such as chlorinated solvents, other organics, metals, inorganics, and radionuclides. The contaminants are concentrated and either degraded or retained in the barrier material, which may need to be replaced periodically. There are approximately 100 PRBs operating in the United States and at least 25 internationally.
PRBs can be installed as permanent or semi-permanent units. The most commonly used PRB configuration is that of a continuous trench in which the treatment material is backfilled. The trench is perpendicular to and intersects the ground-water plume. Another frequently used configuration is the funnel and gate, in which low-permeability walls (the funnel) direct the ground-water plume toward a permeable treatment zone (the gate). Some gates are in situ reactors that are readily accessible to facilitate the removal and replacement of reactive media. These PRBs use collection trenches, funnels, or complete containment to capture the plume and pass the ground water, by gravity or hydraulic head, through a vessel containing either a single treatment medium or sequential media. In circumstances where in situ treatment is found to be impracticable, reactive vessels have been located above ground.
Zero-valent iron has performed so successfully in PRB technology that it is now being applied directly for source zone treatment. Though this measure is not considered a PRB, examples of the technology will be included in the PRB pages because the reactive media and treatment mechanism are related. Pneumatic fracturing and injection, hydraulic fracturing, and injection via direct push rigs have been used successfully to introduce the reactive media to the ground-water or soil source area.
Source: US-EPA, Clu-In: http://www.clu-in.org/techfocus/default.focus/sec/Permeable_Reactive_Barriers%2C_Permeable_Treatment_Zones%2C_and_Application_of_Zero-Valent_Iron/cat/Overview/
precautionary principle orientate us in the decision wheather and action should be done or should not be done if the information on the risk is not vaialable or not satisfactory. Precautionary principle should be applied when there is no certain information on risk.
The principle implies that there is a social responsibility to protect the public from exposure to harm, when scientific investigation has found a plausible risk.
Precaution may be defined as "caution in advance," "caution practised in the context of uncertainty," or informed prudence. All definitions have two key elements.
- an expression of a need by decision-makers to anticipate harm before it occurs. Within this element lies an implicit reversal of the onus of proof: under the precautionary principle it is the responsibility of an activity proponent to establish that the proposed activity will not (or is very unlikely to) result in significant harm.
- the establishment of an obligation, if the level of harm may be high, for action to prevent or minimise such harm even when the absence of scientific certainty makes it difficult to predict the likelihood of harm occurring, or the level of harm should it occur. The need for control measures increases with both the level of possible harm and the degree of uncertainty.
The European Commission issued a Communication on the precautionary principle in 2000, in which it adopted a procedure for the application of this concept,accepting the Lisbon Treaty advise:
"Union policy on the environment shall aim at a high level of protection taking into account the diversity of situations in the various regions of the Union. It shall be based on the precautionary principle and on the principles that preventive action should be taken, that environmental damage should as a priority be rectified at source and that the polluter should pay."
Fields typically concerned by the precautionary principle are the possibility of:
- Global warming or abrupt climate change in general
- Extinction of species
- Introduction of new and potentially harmful products into the environment, threatening biodiversity (e.g., genetically modified organisms)
- Threats to public health, due to new diseases and techniques (e.g., AIDS transmitted through blood transfusion)
- Long term effects of new technologies (e.g. health concerns regarding radiation from cell phones and other electronics communications devices Mobile phone radiation and health)
- Persistent or acute pollution (asbestos, endocrine disruptors...)
- Food safety (e.g., Creutzfeldt-Jakob disease)
- Other new biosafety issues (e.g., artificial life, new molecules)
The precautionary principle is often applied to biological fields because changes cannot be easily contained and have the potential of being global. The principle has less relevance to contained fields such as aeronautics, where the few people undergoing risk have given informed consent (e.g., a test pilot). In the case of technological innovation, containment of impact tends to be more difficult if that technology can self-replicate. Bill Joy emphasized the dangers of replicating genetic technology, nanotechnology, and robotic technology in his article in Wired Magazine, "Why the future doesn't need us", though he does not specifically cite the precautionary principle. The application of the principle can be seen in the public policy of requiring pharmaceutical companies to carry out clinical trials to showhttp://enfo.hu/mokka/secure/.tmp/glossary/glossary_edit.php that new medications are safe.
The costs and social consequences (increased fear in humans) of the application of the precautionary principle are not clearly beneficial.
Sources:
http://en.wikipedia.org/wiki/Precautionary_principle
Communication from the Commission on the precautionary principle, COM(2000) 1
precautionary statements (P) is part of the Globally Harmonized System of Classification and Labelling of Chemicals (GHS). These arestandardized phrases giving advice about the correct handling of chemical substances and mixtures. P-statement replace the S-phrases, used by DSD (Dangerous Substances Directive).
Precautionary statements are one of the key elements for the labelling of chemical substances and products under the GHS, together with the exact identicifation of the product,hazard pictograms, signal word – either DANGER or WARNING, hazard statements, indicating the nature and degree of the risks posed by the product and the identity of the supplier (manufacturer or importer).
Each precautionary statement is designated a code, starting with the letter P and followed by three digits. Some precautionary phrases are combinations, indicated by a plus sign "+".
General precautionary statements
* P101: If medical advice is needed, have product container or label at hand
* P102: Keep out of reach of children
* P103: Read label before use
Prevention precautionary statements
* P201: Obtain special instructions before use
* P202: Do not handle until all safety precautions have been read and understood
* P210: Keep away from heat/sparks/open flames/hot surfaces – No smoking
* P211: Do not spray on an open flame or other igntion source
* P220: Keep/Store away from clothing/…/combustible materials
* P221: Take any precaustion to avoid mixinn with combustibles
* P222: Do not allow contact with air
* P223: Keep away from any possible contact with water, because of violent reaction and possible flash fire
* P230: Keep wetted with …
* P231: Handle under inert gas
* P232: Protect from moisture
* P233: Keep container tightly closed
* P234: Keep only in original container
* P235: Keep cool
* P240: Ground/bond container and receiving equipment
* P241: Use explosion-proof electrical/ventilating/light/…/equipment
* P242: Use only non-sparking tools
* P243: Take precautionary measures against static discharge
* P244: Keep reduction valves free from grease and oil
* P250: Do not subject to grinding/shock/…/friction
* P251: Pressurized container – Do not pierce or burn, even after use
* P260: Do not breathe dust/fume/gas/mist/vapours/spray
* P261: Avoid breathing dust/fume/gas/mist/vapours/spray
* P262: Do not get in eyes, on skin, or on clothing
* P263: Avoid contact during pregnancy/while nursing
* P264: Wash … thoroughly after handling
* P270: Do not eat, drink or smoke when using this product
* P271: Use only outdoors or in a well-ventilated area
* P272: Contaminated work clothing should not be allowed out of the workplace
* P273: Avoid release to the environment
* P280: Wear protective gloves/protective clothing/eye protection/face protection
* P281: Use personal protective equipment as required
* P282: Wear cold insulating gloves/face shield/eye protection
* P283: Wear fire/flame resistant/retardant clothing
* P284: Wear respiratory protection
* P285: In case of inadequate ventilation wear respiratory protection
* P231+232: Handle under inert gas. Protect from moisture
* P235+410: Keep cool. Protect from sunlight
Response precautionary statements
* P301: IF SWALLOWED:
* P302: IF ON SKIN:
* P303: IF ON SKIN (or hair):
* P304: IF INHALED:
* P305: IF IN EYES:
* P306: IF ON CLOTHING:
* P307: IF exposed:
* P308: IF exposed or concerned:
* P309: IF exposed or you feel unwell:
* P310: Immediately call a POISON CENTER or doctor/physician
* P311: Call a POISON CENTER or doctor/physician
* P312: Call a POISON CENTER or doctor/physician if you feel unwell
* P313: Get medical advice/attention
* P314: Get Medical advice/attention if you feel unwell
* P315: Get immediate medical advice/attention
* P320: Specific treatment is urgent (see … on this label)
* P321: Specific treatment (see … on this label)
* P322: Specific measures (see … on this label)
* P330: Rinse mouth
* P331: Do NOT induce vomiting
* P332: If skin irritation occurs:
* P333: If skin irritation or a rash occurs:
* P334: Immerse in cool water/wrap in wet bandages
* P335: Brush off loose particles from skin
* P336: Thaw frosted parts with lukewarm water. Do not rub affected areas
* P337: If eye irritation persists:
* P338: Remove contact lenses if present and easy to do. continue rinsing
* P340: Remove victim to fresh air and keep at rest in a position comfortable for breathing
* P341: If breathing is difficult, remove victim to fresh air and keep at rest in a position comfortable for breathing
* P342: If experiencing respiratory symptoms:
* P350: Gently wash with soap and water
* P351: Rinse continuously with water for several minutes
* P352: Wash with soap and water
* P353: Rinse skin with water/shower
* P360: Rinse immediately contaminated clothing and skin with plenty of water before removing clothes
* P361: Remove/Take off immediately all contaminated clothing
* P362: Take off contaminated clothing and wash before reuse
* P363: Wash contaminated clothing before reuse
* P370: In case of fire:
* P371: In case of major fire and large quantities:
* P372: Explosion risk in case of fire
* P373: DO NOT fight fire when fire reaches explosives
* P374: Fight fire with normal precautions from a reasonable distance
* P375: Fight fire remotely due to the risk of explosion
* P376: Stop leak if safe to do so
* P377: Leaking gas fire – do not extinguish unless leak can be stopped safely
* P378: Use … for extinction
* P380: Evacuate area
* P381: Eliminate all ignition sources if safe to do so
* <span class="abbr" style="color: blue; border-bottom: 1px dotted blue" title="Error in hazard statements">P391: Collect spillage
* P301+310: IF SWALLOWED: Immediately call a POISON CENTER or doctor/physician
* P301+312: IF SWALLOWED: Call a POISON CENTER or doctor/physician if you feel unwell
* P301+330+331: IF SWALLOWED: Rinse mouth. Do NOT induce vomiting
* P302+334: IF ON SKIN: Immerse in cool water/wrap in wet bandages
* P302+350: IF ON SKIN: Gently wash with soap and water
* P302+352: IF ON SKIN: Wash with soap and water
* P303+361+353: IF ON SKIN (or hair): Remove/Take off immediately all contaminated clothing. Rinse skin with water/shower
* P304+312: IF INHALED: Call a POISON CENTER or doctor/physician if you feel unwell
* P304+340: IF INHALED: Remove victim to fresh air and keep at rest in a position comfortable for breathing
* P304+341: IF INHALED: If breathing is difficult, remove victim to fresh air and keep at rest in a position comfortable for breathing
* P305+351+338: IF IN EYES: Rinse continuously with water for several minutes. Remove contact lenses if present and easy to do – continue rinsing
* P306+360: IF ON CLOTHING: Rinse immediately contaminated clothing and skin with plenty of water before removing clothes
* P307+311: IF exposed: Call a POISON CENTER or doctor/physician
* P308+313: IF exposed or concerned: Get medical advice/attention
* P309+311: IF exposed or you feel unwell: Call a POISON CENTER or doctor/physician
* P332+313: If skin irritation occurs: Get medical advice/attention
* P333+313: If skin irritation or a rash occurs: Get medical advice/attention
* P335+334: Brush off loose particles from skin. Immerse in cool water/wrap in wet bandages
* P337+313: Get medical advice/attention
* P342+311: Call a POISON CENTER or doctor/physician
* P370+376: In case of fire: Stop leak if safe to do so
* P370+378: In case of fire: Use … for extinction
* P370+380: In case of fire: Evacuate area
* P370+380+375: In case of fire: Evacuate area. Fight fire remotely due to the risk of explosion
* P371+380+375: In case of major fire and large quantities: Evacuate area. Fight fire remotely due to the risk of explosion
Storage precautionary statements
* P401: Store …
* P402: Store in a dry place
* P403: Store in a well ventilated place
* P404: Store in a closed container
* P405: Store locked up
* P406: Store in a corrosive resistant/… container with a resistant inner liner
* P407: Maintain air gap between stacks/pallets
* P410: Protect from sunlight
* P411: Store at temperatures not exceeding … °C/… °F
* P412: Do not expose to temperatures exceeding 50 °C/122 °F
* P420: Store away from other materials
* P422: Store contents under …
* P402+404: Store in a dry place. Store in a closed container
* P403+233: Store in a well ventilated place. Keep container tightly closed
* P403+235: Store in a well ventilated place. Keep cool
* P410+403: Protect from sunlight. Store in a well ventilated place
* P410+412: Protect from sunlight. Do not expose to temperatures exceeding 50 °C/122 °F
* P411+235: Store at temperatures not exceeding … °C/… °F. Keep cool
Disposal precautionary statements
* P501: Dispose of contents/container to ..
precision of a measurement system, also called reproducibility or repeatability, is the degree to which repeated measurements under unchanged conditions show the same results.
The precision of a measurement system, also called reproducibility or repeatability, is the degree to which repeated measurements under unchanged conditions show the same results.Although the two words reproducibility and repeatability can be synonymous in colloquial use, they are deliberately contrasted in the context of the scientific method.
A measurement system can be accurate but not precise, precise but not accurate, neither, or both. For example, if an experiment contains a systematic error, then increasing the sample size generally increases precision but does not improve accuracy. The result would be a consistent yet inaccurate string of results from the flawed experiment. Eliminating the systematic error improves accuracy but does not change precision.
A measurement system is designated valid if it is both accurate and precise. Related terms include bias (non-random or directed effects caused by a factor or factors unrelated to the independent variable) and error (random variability).
Source: http://en.wikipedia.org/wiki/Accuracy_and_precision
The precision of a measurement system, also called reproducibility or repeatability, is the degree to which repeated measurements under unchanged conditions show the same results.
Precision shoul be distingueshed from accuracy.
A measurement system can be accurate but not precise, precise but not accurate, neither, or both.
For example, if an experiment contains a systematic error, then increasing the sample size generally increases precision but does not improve accuracy. The result would be a consistent yet inaccurate string of results from the flawed experiment. Eliminating the systematic error improves accuracy but does not change precision.
predictable death is a term used in toxicity tests when the presence of clinical signs indicative of death at a known time in the future before the planned end of the experiment, for example: inability to reach water or food.
concentration of the substance below which adverse effects in the environmental sphere of concern are not expected to occur. PNEC is relevant for an ecosystem, e.g. aquatic or terrestrial. PNEC is generally calculated from the ecotoxicity test results of testorganisms of three different trophic levels by factorial extrapolation, using safety factors or by statistical extrapolation.
Applying factorial extrapolation the following assessment factors are applied according to uniform protocols:
f=1000: at least one short-term EC50 from each of three trophic levels,
f = 100: long-term NOEC from one trophic level besides 2 acute,
f = 50: long-term NOEC from species representing two trophic levels besides one acute,
f = 10: long-term NOEC from at least three trophic levels,
f = 1: PNEC can be directly measured in microcosms, mesocosms or ecosystem-field-testing.
Another method to determine a PNEC value is the use of statistical extrapolation methods using the variation in species sensitivity. If a large data set with NOECs from long-term experiments for different taxonomic groups is available, these values can be used to draw a distribution. This distribution that describes the variability of hazard of a substance to organisms is called a Species Sensitivity Distribution (SSD). This distribution can be presented as a frequency distribution (cumulative normal distribution curves or other similar distribution curves) of NOEC values for species. From this curve we can read Xm, the mean toxicity expressed as the mean NOEC value of a substance. The Sm represents the toxicity range or variation in sensitivity of a substance.
The main assumption on the use of SSDs in risk assessment is that the distribution based on a selection of species (tested in laboratory experiments) are representative for all species (in the field).
Statistical extrapolation methods may be used to derive a PNEC from a SSD by taking a prescribed percentile of this distribution. For pragmatic reasons it has been decided that the concentration corresponding with the point in the SSD profile below which 5% of the species occur, should be derived as an intermediate value in the determination of a PNEC. This 5% point in the SSD is also identified as a hazardous concentration (HC) at which a certain percentage (in this case 5%) of all species is assumed to be affected.
CPU, Central Processing Unit in computers
transgenic animals may be developed for a wide range of purposes. Some of the areas in which transgenic animals are important are: medical research, livestock improvement, pharming and xenotransplantation.
Pharming means the production of biologically active human proteins, diagnostics, monoclonal antobodies, and nutraceuticals.
prokaryotes are organisms whose genetic material (filaments of DNA) is not enclosed by a nuclear membrane, and that do not possess mitochondria, plastids or other cell organelles. Bacteria and cyanophyta are the only prokaryotic organisms.
a protected species is any plant or animal a government declares by law to warrant protection. Most protected species are considered either threatened or endangered. In these cases, a government establishes certain rules regarding the species, that if violated, can result in fines or criminal prosecution.
The impetus behind protected species laws is risk of species extinction. Ecologists have demonstrated that losing even the smallest of species can have a direct effect on the rest of the plant and animal population. For example, a grass eaten by a specific animal becomes extinct due to habitat destruction. The animal may die off as a result of not finding its food source available, causing further disruptions in the food chain.
Source: http://www.wisegeek.com/what-is-a-protected-species.htm
proteomics is the study of protein molecules in the cell to find association with the composition and cellular response to toxic chemical substances. It is an innovative tool in pharmacology, toxicology and environmental toxicology.
Proteins are the primary structural and functional molecules in the cell, and are made up of a linear arrangement of amino acids. The linear polypeptide chains are folded into secondary and tertiary structures to form the functional protein. Unlike the static nature of the cell's genes, proteins are constantly changing to meet the needs of the cell.
Characterizing the identity, function, regulation, and interaction of all of the cellular proteins of an organism, the proteome, will be a major achievement. Studies of changes in the proteome of cells and tissues exposed to toxic materials, compared to normal cells, is being used to develop an understanding of the mechanisms of toxicity. As proteomics tools become more powerful and widely used, protein and proteome changes in response to exposures to toxic substances (fingerprints or response profiles) will be developed into databases that can be used to classify exposure responses at various levels of organization of the organism, thus providing a predictive in silico toxicology tool.
pump and treat is the technology which involves the xtraction of groundwater from an aquifer and subsequent treatment above ground. Extraction is usually conducted by pumping groundwater from a well or trench. Treatment can include a variety of technologies that reduce contaminant toxicity or mobility. Some of the commonly used above-ground treatment technologies are air stripping, activated carbon adsorption, filtration, and metals precipitation.
pyrolysis is the chemical decomposition of organic substances by heating. pyrolysis is a special case of thermolysis. During pyrolysis no oxigen is present, so that it is diffent of combustion. It may proceed in isolated space or under water. It occurs spontaneously at high temperatures and in general, it produces gas and liquid form products and leaves a solid residue rich in carbon. pyrolysis on extreme temperature leaves elementary carbon as residue, it is called carbonization. The pyrolísis in water is also called hydrous pyrolysis. The efficiency of pyrolysis can extremely be increased by using special catalists.