ČSN ISO 6107 - Kvalita vod - Slovník

3.549 sulphite-reducing

 clostridia large group of Gram-positive anaerobic bacteria which form spores

Note 1 to entry: See also ISO 6461-1 and ISO 6461-2.

Note 2 to entry: Their natural habitat is the soil or the large intestine of humans and animals. Most species are saprophytic organisms in the soil. Their spores can survive for long periods in faeces, soil, dust and water. Their presence in water can be used to detect remote or intermittent faecal pollution. They are able to reduce sulphites to sulphides.

3.550 supply water water, which usually has been treated, that passes into a distribution network or a service reservoir

3.551 supralittoral zone zone above the eulittoral zone (3.213), which is reached by spray water

Note 1 to entry: Its upper limit is normally determined by the upper limit of Verrucaria (black lichen belt), cyanobacteria (usually Calothrix scopulorum) or littorinid snails.

3.552 surface active agent chemical compound possessing surface activity which when dissolved in a liquid, in particular water, lowers the surface tension or interfacial tension by preferred

adsorption at the liquid/vapour surface or other interfaces

Note 1 to entry: The chemical compound must include in its molecules at least one group with an affinity to markedly polar surfaces, ensuring in most cases its dissolution in water, and a non-polar group which has little affinity to water.

Note 2 to entry: The rate is usually expressed as cubic metres per square metre per day.