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The natural environment

18 important questions on The natural environment

Mass balance (Section 10.2.1)

The notion of mass balance means that if there is an increase in the amount of a chemical present in a given environment, this chemical must either have been transported from elsewhere or produced by a chemical or biological reaction from other compounds (law of conservation).

Energy balance (Section 10.2.2)

The movement of energy (i.e. the ability to do work) and changes in its form can be tracked by means of an energy balance, analogous to a mass balance. The first law of thermodynamics states that in an isolated closed system, energy will be conserved and can be neither created nor destroyed. Conservation of energy provides a basis for energy balances.

Biodegradation (Section 10.3.4)

The chemical and biological breakdown of inorganic and organic complexes.

Enthalpy (Section 10.3.1)

The energy of the inter- and intra-molecular bonds that bind the system’s atoms and molecules together

Gibbs free energy (Section 10.3.1)

That energy available within a given system for doing work. Gibbs free energy (G) is related to the system’s enthalpy (H), entropy (S) and temperature (T). G = H − T x S.

Photochemical transformations (Section 10.3.3)

When a chemical compound (an organic pollutant in the aquatic environment, for example) absorbs light it may undergo photochemical transformation, either directly or indirectly.

Biodiversity (Section 10.4.3)

Biological diversity.

Biogeochemical cycles (Section 10.4.5)

Cycling of chemical elements within and between the atmosphere, hydrosphere, lithosphere and biosphere.

Eutrophication (Section 10.4.5)

The enrichment of terrestrial and aquatic systems with nutrients, in particular nitrogen and phosphorus.

Genetic drift (Section 10.4.1)

The chance that a genetically fixed characteristic will disappear from the population, leading to a more uniform and hence more vulnerable population.

Genetic erosion (Section 10.4.1)

Decrease in genetic variability.

Genetic variability (Section 10.4.1)

Variation in genetically fixed characteristics.

Population (Section 10.4.1)

A group of individuals of one species in an area, though the size and nature of that area is defined, often arbitrarily, for the purpose of the study being undertaken.

Bioavailability (Section 10.5.2)

The ability of a substance to affect organisms; it is a measure of the physicochemical access that a toxicant has to the biological processes of an organism.

Ecotoxicology (Section 10.5.2)

The science concerned with the environmental fate and toxic effects of chemicals in natural and disturbed ecosystems.

AMOEBA method (Section 10.6.4)

General Method for Ecological Description; a semi-quantitative method for describing and assessing the quality of aquatic ecosystems. A circle represents the target image formulated for

indicators (e.g. indicator species) for the long term, while the slices (as in a pie-like radar diagram) represent the target variables.

Index of biotic integrity – IBI (Section 10.6.1)

An composite index incorporating scores for a number of biological attributes within an ecosystem and comparing these metrics with a relatively undisturbed situation. This index is typically used for water ecosystems.

TRIAD method (Section 10.6.2)

An environmental monitoring approach, which integrates methods from several sciences, combining chemical and ecological data with bioassay results to assess the quality of a terrestrial or aquatic compartment or habitat.

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Principles of Environmental Sciences

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The natural environment

18 important questions on The natural environment

Mass balance (Section 10.2.1)

Energy balance (Section 10.2.2)

Biodegradation (Section 10.3.4)

Enthalpy (Section 10.3.1)

Gibbs free energy (Section 10.3.1)

Photochemical transformations (Section 10.3.3)

Biodiversity (Section 10.4.3)

Biogeochemical cycles (Section 10.4.5)

Eutrophication (Section 10.4.5)

Genetic drift (Section 10.4.1)

Genetic erosion (Section 10.4.1)

Genetic variability (Section 10.4.1)

Population (Section 10.4.1)

Bioavailability (Section 10.5.2)

Ecotoxicology (Section 10.5.2)

AMOEBA method (Section 10.6.4)

Index of biotic integrity – IBI (Section 10.6.1)

TRIAD method (Section 10.6.2)

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