Overview

Diatoms are an important component of aquatic ecosystems and constitute a water quality monitoring tool where the primary objective is either a measure of ecological status or the impact of specific components of water quality (for example eutrophication, acidification). The requirement for the monitoring of such processes is inherent in the Water Framework Directive (2000/60/EC) and Urban Waste Water Treatment Directive (91/217/EEC) in addition to other EU Directives and international agreements. This European Standard covers aspects of identification and enumeration of the relative abundance of diatom taxa on prepared slides and of data interpretation relevant to assessment of water quality. The use of diatoms as indicators of river and lake quality is widely accepted both in Europe and beyond. The methodology is based on the fact that all diatom species have tolerance limits and optima with respect to their preference for environmental conditions such as nutrients, organic pollution, pH value, etcetera. Polluted waters will tend to support an increased abundance of those species whose optima correspond with the levels of the pollutant in question. Conversely, certain species are intolerant of elevated levels of one or more pollutants, whilst others can occur in a wide range of water qualities. Methods using diatoms to assess water quality have been developed in several European countries; recent work is summarized in the proceedings of three symposia. According to the precise usage to which this European Standard is to be put it is essential for specifiers and users to mutually agree on any necessary variations or optional procedural details prior to use. Special care should be taken that some indices and methods used at national level provide special requirements whereas this European Standard includes the full range of permissible options. Under these circumstances, the respective requirements for the application of a special index should take precedence. This document specifies a method for the identification and enumeration of relative proportions of diatom taxa on prepared slides and of data interpretation relevant to assessments of water quality in rivers and lakes. It is suitable for use with indices and assessment methods based on the relative abundance of taxa. The methods for identification and enumeration may also be applied to the study of benthic diatoms in other habitats provided that data interpretation methods appropriate to these habitats are used. Compared with DIN EN 14407:2004-10, the following changes have been made: a) the title has been changed; b) the scope of this European Standard has been expanded to include lakes; c) the informative Annex A "Example for quality assurance of diatom analyses from the UK" has been added; d) the standard has been editorially revised. The preliminary work has been carried out by Working Group CEN/TC 230 (WG 2) ("Biological methods") under the chairmanship of BSI (secretariat: United Kingdom). Regarding the German collaboration NA 119-01-03-05-06 AK "Biologisch-ökologische Gewässeruntersuchung" ("Biological-ecological water examination") of NA 119-01-03 AA "Wasseruntersuchung" ("Water examination") at the Water Practice Standards Committee (NAW) was involved in the preparation. The national revision of this project was funded by the Länderfinanzierungsprogramm "Wasser, Boden und Abfall" (Federal funding programme "Water, soil and waste").

Document: references other documents

Responsible national committee

NA 119-01-03-05-06 AK - Biological-ecological water examination  

Responsible european committee

CEN/TC 230/WG 2 - Biological methods co-ordination group