Canal/Channel:
un artificial waterway. In the context of the Lagoon of Venice, these include the canals within Venice city centre and those crossing dry land in the catchment area (which have clearly visible banks), and the navigable channels crossing the open waters of the Lagoon which (whose edges are marked by the bricole). Many of the canals are actually natural in origin, though they may have been expanded artificially. See also rio and ghebo.

Carrying capacity:
the capacity of an environmental system to maintain indefinitely one or more species. For human beings it is the maximum capacity of the system to provide resources – and the maximum capacity of the system to assimilate waste – without being irreversibly modified.

Carbonates (carbonatic rocks):
rocks belonging to the family of sedimentary rocks. Includes calcareous and Dolomitic rocks, mostly composed of calcium carbonate and magnesium carbonate. Cf. Plate 9.

Carbon:
chemical element, symbol C, non-metal. Carbon is the essential component of the chemistry of living organisms. In nature it is found in its crystalline state as diamonds or graphite; in its amorphous state it is contained in coal. Carbon compounds are either organic, of which there exist an enormous number, or inorganic. The latter are divided into oxides (e.g., carbon monoxide CO, carbon dioxide CO₂), carbonates, compounds with non-metals (e.g., chlorides, sulphides, etc.) and compounds with metals (carbides).

Cartography:
science derived from geography comprising all the scientific, technical and artistic operations necessary for the creation of maps and the various systems of graphical representation based on direct surveys of the terrain and other cartographical or documentary sources. The term cartography refers not only to the production but also to the applications of maps and their interpretation. Cartographical information memorised and managed by computer is known as digital cartography: it facilitates the reproduction and transmission of information, and increases the capacity for analysing the data associated with it (management of data via Geographical Information Systems, generation of threedimensional models of the terrain etc.).

Cassa di colmata (landfill):
system of reclamation by channelling the flood waters of a river, rich in suspended solid material, into an empty basin enclosed by dykes in order to gradually raise the bed until it is full. In the Lagoon of Venice the term refers to the wetlands of artificial origin created using the sediments from the excavation of the Canale dei Petroli shipping channel. These wetlands had previously been an area of saltmarshes, pools, and channels, but were reclaimed in the 1960s as a site for the third industrial zone, never built.

Catchment area (or drainage basin):
an area from which all the water falling as rain, snow, etc., flows into the same river. Italian law defines it as follows: «The territory from which rainwater or waters from melted snow and glaciers, flowing across the surface, gather in a given watercourse either directly or by means of tributaries, together with the territory that can be flooded by the waters of the same watercourse, including its terminal stretches with the mouth(s) at sea and the nearby coastline» (article 1, Law 183 of May 18, 1989). In the context of this Atlas, it usually refers to the area from which the water falling as rain, snow, etc., drains into the Lagoon of Venice, either directly or by means of watercourses.

Cation:
ion having a positive charge.

Charadriiformes:
order of birds to which belong the seagull and the snipe.

Chlorophyll:
green pigment found in leaves, indispensable for photosynthesis. Chlorophyll a, a type of chlorophyll. Cf. Plates 54, 55.

Ciconiiformes:
order of aquatic birds of medium to large dimensions, to which belong herons, swans and ibises.

Class:
in taxonomy, a unit used in the hierarchical classification of living things, proposed for the first time in the eighteenth century by Linnaeus. A class includes a number of orders, and a number of classes make up a phylum.

Clay:
incoherent material made up of grains smaller than 0.004 mm. Clay is able to hold large quantities of water, which adheres to the surface of the grains, and some varieties may swell when they absorb water. Cf. Plate 9.

COD:
Chemical Oxygen Demand (expressed in mg/L of O₂); the quantity of oxygen necessary for the complete chemical oxidation of the organic and inorganic compounds present in a sample of water. It is an indicator of the concentration in the water of substances that can be chemically oxidised, mainly organic matter, and is thus closely linked to pollution levels.

Colloidal particles:
the complex of particles containing organic substances and minerals, including proteins, pectins, neutral polysaccharides, polymerised phenolic compounds, copper sulphate, iron phosphate etc. Colloidal particles are invisible under an optical microscope but are however too large to pass through cellular membranes.

Community:
all the living things that live in a given moment in the same place.

Conterminazione:
(Italian) the official boundary of the Lagoon, within which the laws and regulations for safeguarding the environment of the Lagoon are valid. Started in 1610 by order the Senate of the Venetian Republic, it was completed in 1792. In 1990 the boundaries of the Lagoon were brought up to date, and now include the waters in the three bocche di porto and the island of Sant’Erasmo. Marked by boundary stones.

Core, sample core, sediment core:
cylindrical sample of rock, sediment or soil, obtained by perforation. Core samples serve to study the structure and stratigraphy of substrates.

CORINE Land Cover:
a joint initiative by the European Environment Agency and the European Commission, currently affecting 26 countries; the project has created maps of soil coverage and changes. The Agency for the Protection of the Environment and Related Technical Services (APAT) is the national authority charged with the implementation and updating of the project in Italy and with the distribution of the results.

Cracking:
process by which the heavy hydrocarbons found in crude oil are split into light hydrocarbons such as those found in petrol and other useful substances. The process takes place at high temperatures and is also known as pyrolysis.

Detritus chain:
specific part of the food chain comprising the organisms that feed on decomposing organic substances, known as detritivores. Cf. Plate 11.

Diatom:
type of unicellular alga.

Dioxins:
the general term “dioxins” refers to a family of about 210 chemical compounds containing chlorine (dioxins and furans), with no commercial value, which are by-products of certain industrial processes (production of chlorine and PVC, use of chlorine in various industrial applications, incineration etc.).