Glossary

A non-living aspect of a system; e.g. geological or meteorological factors.

The loss of mass from a glacier (e.g. by melting).

Physical wearing and grinding of a surface.

The flat part of the ocean floor that lies between about 4 and 6 km below the sea surface.

The gain of mass on a glacier (e.g. by snowfall).

A positively charged ion that is able to interact with its surrounding water molecules to release one or more protons into solution, thus acting as an acid. An example is the Al3+ ion which is hydrated with six molecules of water, as [Al(H2O)6]3+, and can, depending on the solution pH, sequentially release protons, e.g. [Al(H2O)6]3+ ⇌ [Al(H2O)5OH]2+ + H+

Liquid precipitation (rain) that is acidic; usually defined as having a pH of less than 5, to avoid confusion with natural acid rain. Emissions such as SO2 and NOx are oxidised in the atmosphere, and the oxidised products dissolve in water vapour, forming sulfuric and nitric acids. These acids increase the acidity of rainfall.

The rate at which evapotranspiration occurs. It is dependent on a number of factors, including soil moisture content, vegetation type, rainfall and air temperature and movement.

An energy-rich molecule which all cells use as a temporary store of energy. It is produced by respiration and used in a very wide array of biochemical processes.

In meteorology, the transport of air from one location to another. The term is generally applied to horizontal movement of air but vertical advection is also possible. Advection necessarily transfers atmospheric properties, such as humidity or cloudiness.

Pertaining to the wind.

Plant tissue type composed of hollow tubes. It is often abundant in the stems and roots of wetland species. It permits internal diffusion of gases within plants.

A measure of the effectiveness of air movement in aiding evaporation, as a function of the ‘roughness’ of the surface over which it blows.

The surface horizon of a mineral soil consisting of organic matter mixed with mineral matter. The A horizon generally has maximum organic matter accumulation, maximum biological activity, and/or eluviation of materials such as iron and aluminium oxides and silicate clays.

Approximately 80% nitrogen and 20% oxygen, plus a number of other gases present in trace quantities.

The proportion of a soil’s volume that is occupied by air.

The reflection coefficient of a surface - the fraction of the amount of incoming radiation that is reflected from a surface.

A calculation or formula that solves a recurrent problem.

A small portion of a total amount of a solution.

Loose (unconsolidated) sediments deposited by flowing water.

Change brought about by geological processes after initial rock formation, especially through the action of hydrothermal fluids.

The soil solution pH (around pH 4.2–3.2) at which changes in pH are buffered by the dissolution of aluminium from clay minerals through the overall reaction: AlOOH(s) + 3H+(aq) ⇌ Al3+(aq) + 2H2O(l) Aluminium toxicity can be a major problem for soil biota and plant roots within this pH buffer range.

Minerals containing aluminium and silicon. In aluminosilicate minerals, aluminium (3+) replaces some silicon (4+), so one extra positive metal ion is needed for every silicon replaced.

Clay minerals containing aluminium and silicon. In aluminosilicate minerals, aluminium (3+) replaces some silicon (4+), so one extra positive metal ion is needed for every silicon replaced