Glossary Eniscuola

A-B-C

AIR SPARGING

An in situ remediation technique, applicable to saturated soil and capillary fringe, which consists of injecting pressurised air at saturated soil level to cause the volatilisation and desorption (stripping) of volatile and semi-volatile organic compounds. The process is often associated with the Soil Vapour Extraction (SVE) system for the recovery of contaminated vapours.

ALCOHOLIC FERMENTATION

The conversion of pyruvate molecules to carbon dioxide and ethyl alcohol (ethanol).

ALLOCHTHONOUS

From the Greek ἄλλος (àllos) 'other', and χθών (chthòn) 'soil/land', it indicates something or someone originating at a distance from their present location.
In geology, rocks or minerals that were not formed at the location but were transported there by external agents or tectonic causes.
In biology, an allochthonous or alien species is defined as any living species that, due to human action, finds itself inhabiting and colonising a territory outside its native range.

ALLOY

A solid solution consisting of more than one element and possessing metallic properties.

APHOTIC ZONE

Area of an aquatic environment below the photic zone, where insufficient light penetrates for photosynthesis to take place.

ATOMIC MASS UNIT

Atomic mass unit: Unit of measurement of relative atomic mass, relative molecular mass and formula weight, 1 u = 1/12 of the mass of the carbon atom 12.

AUTOCHTHONOUS

From Late Latin autochton -ŏnis, Gr. aytókhthōn -onos, comp. of aytós 'same' and khthṓn 'earth'. Indigenous, originating from the same place where it is currently located.
In geology, rock formed in its current location without having undergone tectonic shifts.
In biology and biogeography, a species indigenous to a given region is one that has originated and evolved in the territory in which it is found.

BINOMIAL NOMENCLATURE

Naming system developed by Linnaeus to classify organisms. Each species is defined by two Latin terms: the first indicates the genus, the second the specific name.

BIOAVAILABILITY

Fraction of a nutrient that the body is able to absorb and utilise for its physiological functions. Availability to an organism of certain substances in very low concentrations.

BIOREMEDIATION

A process that uses microorganisms or their enzymes to decontaminate polluted sites and restore them to their original condition. It refers to the set of biological processes performed by micro-organisms, plants, fungi or their enzymes, naturally present in environmental matrices (soil and water) and used as an alternative to traditional remediation processes to remove contaminants in situ, transforming them into non-toxic products or by-products. It is mainly applicable to the remediation of organic compounds.

BIOSPARGING

An in-situ remediation technique, applicable to the saturated zone and the capillary fringe, which consists of injecting oxygen or air at low pressure into the water table to stimulate biodegradation by indigenous micro-organisms (naturally present in the soil) of organic compounds adsorbed to the saturated soil.

BIOTECHNOLOGY

Using living organisms to produce useful substances through molecular biology and genetic engineering techniques.

BIOVENTING

An in situ remediation technique, applicable to unsaturated soil. By introducing oxygen or air at low pressure into the soil layers affected by the presence of organic contaminants, it stimulates biodegradation of organic compounds adsorbed to the unsaturated soil by indigenous micro-organisms (naturally present in the soil). It can be applied in conjunction (alternating phases) with a Soil Vapour Extraction (SVE) process to ensure the removal of both volatile/semi-volatile and non-volatile hydrocarbon fractions.

BUFFER

Solution consisting of a weak acid and its salt with a strong base or a weak base and its salt with a strong acid, which tends to minimise pH changes resulting from the addition of small amounts of acids or bases. There are numerous buffer systems in the body that ensure the maintenance of internal physiological conditions: the main buffer system is the blood.

CHEMOAUTOTROPH

An organism that obtains both energy and carbon from inorganic substances; it produces its organic compounds from CO₂ without using solar energy.

CHEMOHETEROTROPH

An organism that obtains energy and carbon from organic molecules.

CHEMORECEPTOR

A receptor that detects chemical changes within the body or the presence of specific molecules in the external environment.

CONCENTRATION GRADIENT

Change in concentration of a chemical. Cells often maintain an ion concentration gradient across their membranes. When a concentration gradient is present, the ions or other substances involved tend to diffuse from the zone of higher concentration to the zone of lower concentration.

D-E-F

DECOMMISSIONING

All the activities aimed at dismantling an end-of-life asset, including the management of waste materials.

DIFFRACTION

The property of light waves to circumvent obstacles by occupying the shadow zone.

DIFFUSION

The tendency of a particle to move spontaneously from the place where its concentration is highest to the place where it is lowest.

DISTRIBUTION OF RESOURCES

Division of environmental resources by co-existing species based on the principle that the niche of each species is different in one or more significant factors from that of all others.

DNA BARCODING

Method for identifying living species using a short sequence of DNA located in a standard region of the genome. With this technique, proposed in 2003 by Canadian researcher Paul D. N. Herbert, a certain DNA sequence becomes the key to uniquely recognising the species to which an organism belongs, just as a supermarket scanner recognises a product by reading its barcode.

ECOLOGICAL NICHE

A set of environmental resources optimal for the life of a species and the relationships it establishes with others.

ECOTYPE

In biology, this is the name given to the varieties of a species that, despite having the same geographical distribution, have each adapted to their own particular environment (e.g. the head louse and the clothes louse). As such, however, an ecotype has no taxonomic position. The term ecotype was coined in 1922 by the Swedish botanist Göte Turesson.
An ecotype, therefore, is a distinct population of an organism that is closely related in its characteristics to the ecological environment in which it lives.

ECTOTHERM

The body temperature of ectothermic animals such as invertebrates, fish, amphibians and non-bird reptiles, is mainly provided by an external heat source.

ENDOTHERM

An organism, such as a bird or a mammal, that is able to regulate its body temperature by producing endogenous (metabolic) heat.

ENDOTOXINE

A toxin that stays inside the bacterium that produces it and comes out of it when it decomposes.

EX SITU/OFF-SITE TECHNOLOGY

A method of remediation involving the movement of the contaminated environmental matrix from its site of origin and its subsequent treatment in off-site facilities such as authorised treatment plants or landfill.

FERMENTATION

A metabolic process that obtains ATP from the breakdown of glucose by glycolysis: alcoholic fermentation converts pyruvic acid produced by glycolysis into carbon dioxide and ethyl alcohol, while lactic fermentation converts pyruvic acid into lactic acid.

FOSSILISATION

This is the process that leads to the production of a fossil and is a phenomenon that occurs rarely and under special conditions. A necessary condition for the fossilisation process to occur is the rapid isolation of the remains or traces of organisms.

G-H-I

GAMMA RADIATION

Electromagnetic waves consisting of high-energy photons emitted by radioactive atomic nuclei.

GENETIC ENGINEERING

The complex of techniques involving the manipulation of genes of prokaryotic and eukaryotic organisms, and their introduction into other organisms where they are normally absent. Such techniques include, for example, PCR, DNA sequencing and the use of restriction enzymes. An example of application is the production of bacteria that synthesise human hormones or antibiotics.

GEOCHRONOLOGICAL SCALE

Time scale based on the dating of geological strata and fossil finds. The main subdivisions of the geochronological scale are called eras (Precambrian, Paleozoic, Mesozoic and Cenozoic), which in turn are divided into periods. The duration of eras is measured in millions of years.

GEOTROPISM

Geotropism or gravitropism is the external stimulus perceived by plants that enables them to recognise the direction of the force of gravity. Indirectly, therefore, it gives the plant the ability to orient itself vertically in space. Positive geotropism, if the organ grows towards the centre of the earth (as is usually the case with the primary root); negative geotropism, if it grows in the opposite direction (as is very often the case with the primary stem); transverse geotropism or diageotropism, if it is oriented transversely (as is the case with many rhizomes, stem branches and lateral roots).

GTP - GROUNDWATER TREATMENT PLANT

A set of specific processes to remove contaminants from groundwater with the aim of bringing it into conformity with its intended use: re-injection into the aquifer, discharge, internal reuse, sale to third parties. The technologies used are chosen according to the contaminants present and the goals to be achieved. Generally, the plant consists of: chemical-physical sections (SST, colloids, metals), acid and/or basic stripping (VOC), filtration on granular medium (SST), activated carbon filtration (metals, VOC, BTEX), biological treatment (organic compounds), membrane filtration (SST, COD), osmosis (salinity).

HETEROTHERM

An animal can be defined as 'heterothermic' when its body heat regulation system includes a second emergency system. For example, animals at constant body temperature (homeotherms) go into hibernation and lose their ability to produce endogenous heat for a limited period of time. As a result, their body will slow down to a thermal adaptation that involves only exchange with the surrounding medium (the environment) that will lower their temperature. Once they come out of hibernation, their metabolic or endogenous heat production capacities will function once again as before and the temporary ectothermy will end.

HIBERNATION

A physiological state of torpor that allows an organism to survive during long periods of exposure to low temperatures and food shortages. It is characterised by a reduction in metabolism, heart rate, respiratory rate and body temperature.

HOMEOSTASIS

Maintaining the functions and chemical and physical characteristics of an organism despite changes in the external environment.

HOMEOTHERM

An animal capable of maintaining a constant body temperature. It describes a type of heat regulation. Its opposite is heterotherm.

HYDRAULIC BARRIER

To date, hydraulic barrier is one of the most widely used systems for treating contamination in aquifers, although it originated as a containment technique. This technology consists of a series of extraction wells (known as 'barrier wells'), mostly placed transversely to the water outflow, whose action creates piezometric vacuum cones, drawing in the contaminant plume and preventing it from migrating into the surrounding environment. Often a hydraulic barrier is coupled with a treatment system for the discharged water.

HYDROGEN BONDING

A weak bond formed between a very electronegative atom (O, F or N) and a hydrogen atom already covalently bonded to a very electronegative atom (O, F or N); the hydrogen atom of one molecule is attracted to the electronegative atom of the other molecule. Many properties of water and biomolecules are explained by the presence of the hydrogen bond.

IMPRINTING

A simple form of learning established at a specific stage of an animal's development, with a permanent character and a strong innate component; for example, the offspring of many bird species tend to regard the first moving object that appears when the egg hatches as their mother.

INERTISATION

A chemical and/or physical process for the capture and fixation of pollutants in an inert matrix, with the aim of decreasing the polluting potential and hazardousness of waste, making it suitable for subsequent landfilling or recovery. Inertisation processes are divided into stabilisation or solidification, vitrification and glass-ceramisation.

IN SITU TECHNOLOGY

Remediation methods for treating contaminated environmental matrices by processing directly in their natural location (unsaturated soil, saturated soil, groundwater).

INTRINSIC GROWTH RATE

The maximum reproductive capacity of a population placed in an ideal environment with unlimited space and resources.

J-K-L

LACTIC FERMENTATION

The conversion of pyruvate molecules to lactate (lactic acid), without release of carbon dioxide.

M-N-O

MACROEVOLUTION

Evolution leading to the appearance of new species, endowed with new characters and new ways of adapting to the environment. See also: microevolution.

MACROMOLECOLA

A large molecule made up of smaller units joined by covalent bonds; polysaccharides, proteins and nucleic acids are macromolecules.

MACRONUTRIENT

Any substance that an organism needs in large quantities. See also: micronutrient.

MICROEVOLUTION

A variation in the gene pool of a population; the main causes of microevolution are genetic drift (founder effect, bottleneck effect), natural selection, gene flow and occurrence of mutations. See also: macroevolution.

MICRONUTRIENT

An element that an organism needs in very small quantities, such as vitamins; micronutrients are usually components or cofactors of enzymes. See also: macronutrient.

MINERAL SALT

An inorganic compound involved in life processes; it cannot be synthesised by organisms but must be taken in through food.

NITROGEN FIXATION

The conversion of atmospheric molecular nitrogen into nitrogen compounds such as nitrates and ammonia, which plants can absorb and utilise.

OSMOSIS

A phenomenon consisting of the diffusion of solvent (usually water) from a solution of lower concentration to a solution of higher concentration, when the two solutions are separated by a semi-permeable membrane. Cytoplasmic membranes are an example of a semi-permeable membrane; therefore, osmosis plays an important role in controlling the distribution of water in all organisms.

P-Q-R

PANGEA

An ancient supercontinent formed by all the present-day continents joined to form a single landmass. Continental fragmentation and drift, which occurred at the end of the Palaeozoic, resulted in the current distribution of continents on the earth's surface.

PARENTAL IMPRINTING

Parental effect on the expression of certain genes; identical alleles have different effects on offspring depending on whether they are derived from the mother or the father.

PETRIFICATION

This is a phenomenon by which organic remains, especially bones, shells, wood and sometimes even excrement, are turned into stony substances. Petrification can occur through two distinct processes, mineralisation and substitution.

pH SCALE

A scale that measures the acidity or basicity of a solution, with values ranging from 0 (highest acidity) to 14 (highest basicity); a value of 7 indicates neutrality. The term pH denotes the inverse of the logarithm of the concentration of hydrogen ions (H+). The lower the pH value, the higher the concentration of hydrogen ions in the solution.

PHOTIC ZONE

Layer of surface water where light can penetrate, allowing photosynthesis to take place.

PHYTODEPURATION

Application of phytoremediation to contaminated water (groundwater, surface water, industrial effluent, stratum water, landfill leachate) through submerged flow or surface flow systems such as wetlands. The purification mechanisms take place through physical, chemical and biological processes (filtration, absorption, assimilation by plant organisms and bacterial degradation).

PHYTOREMEDIATION

A technology that uses the action of plants to treat contaminated environmental matrices. The purifying action is concentrated at the level of the rhizosphere (portion of soil surrounding plant roots) and exploits the synergies between plant roots, bacteria and fungi. The removal of contaminants is mediated by different processes and can therefore be classified into phytoextraction, phytodegradation, phytostabilisation and phytovolatilisation. It is applicable to heavy metals, radionuclides, chlorinated solvents, BTEX, PCBs, PAHs, pesticides.

PUMP & TREAT

A groundwater remediation technique consisting of the extraction of contaminated groundwater through boreholes and its subsequent treatment at a dedicated plant. The purified water can then be either channelled into the sewage system or into surface water bodies, reused in industrial activities or reintroduced into the aquifer via re-injection wells.

REACTION RATE

The change in concentration of a reagent or product per unit time.

REMEDIATION

The set of steps designed to eliminate sources of pollution and pollutants or to reduce the concentrations of the same in the soil, subsoil and groundwater to a level equal to or below the values of the risk threshold concentrations (RTC).

RETROVIRUS

RNA viruses equipped with the enzyme reverse transcriptase, which form a DNA copy of their own genome during their reproductive cycle in the host cell. The double-stranded DNA produced from the viral RNA integrates into the genome of the cell in the form of proviruses. Retroviruses cause diseases with a long incubation and slow development and include HIV and various types of carcinogenic viruses.

S-T-U

SATURATED SOIL

The deepest zone of soil: within it, pores are saturated with water. The movement of groundwater is mostly horizontal and determined by the hydraulic load difference under the control of gravity.

SOIL VAPOUR EXTRACTION

A contaminated soil remediation technique suitable for the removal of voatile and semi-volatile organic compounds in homogeneous, medium to coarse-textured soils with medium to high permeability, at the unsaturated zone (with an underlying saturated zone > 2-3 m). It is based on the generation of a flow of air in the subsurface through the application of a pressure gradient via horizontal trenches or vertical and horizontal wells, followed by the extraction and recovery of interstitial air in the unsaturated soil. The extracted exhaust air is then captured and sent for subsequent purification treatment.

SOIL WASHING

An ex situ (on-site and off-site) soil remediation technique suitable for the removal of contaminants in the fine fractions of soil which, once extracted, are sieved to separate the coarse fractions from the fine fractions, which are then subjected to solvent washing. It is effective on petroleum hydrocarbons, VOCS, SVOCS and halogenated contaminants, but also on recalcitrant compounds such as PAHs, PCBs, dioxins and furans, pesticides and metals/metalloids.

UNSATURATED SOIL

Soil surface zone: within this zone, the interstitial spaces (i.e. the spaces – or pores – between individual soil particles) are not fully saturated and may contain gas or water in varying proportions, but in a non-saturated condition. The movement of fluids is typically vertical and due to the force of gravity. This natural phenomenon, identified by the term 'percolation', allows rainwater, for example, to infiltrate the pores of the soil.

V-W-X

VISIBLE LIGHT

All electromagnetic radiation visible to the human eye, having a wavelength between 380 and 760 nm.

WAVELENGTH (LAMBDA)

The distance between the adjacent crests (highest points) of two adjacent waves, such as waves of the electromagnetic spectrum or sound waves; it is inversely proportional to frequency.