Page 63 - Freshwater-Biology-and-Ecology-Handbook

5.4 General physico-chemical quality elements

The general chemical and physico-chemical quality elements describe water quality. They include chemical
substances, such as nutrients, and physical properties, such as the thermal regime. At high ecological status, the
condition of each element must be within the range of conditions normally associated with undisturbed conditions.
At good ecological status, the Directive requires that the general physico-chemical quality elements comply with
standards established by the Member State to protect the functioning of the ecosystem.

Table 1.9
General chemical and physico-chemical quality elements relevant to the different categories of surface water

Indicators for which standards have been
Water category Quality elements
proposed by UKTAG
1 Thermal conditions 1 Temperature
2 Oxygenation conditions 2 Dissolved oxygen concentration
Rivers 3 Salinity 3 -
4 Acidification status 4 pH
5 Nutrient conditions 5 Soluble reactive phosphorus concentration
1 Transparency 1 -
2 Thermal conditions 2 -
3 Oxygenation conditions 3 Dissolved oxygen concentration
Lakes
4 Salinity 4 Conductivity
5 Acidification status 5 Acid neutralising capacity
6 Nutrient conditions 6 Total phosphorus concentration
1 Transparency 1 -
Transitional 2 Thermal conditions 2 -
waters (eg 3 Oxygenation conditions 3 Dissolved oxygen concentration
estuaries)
4 Nutrient conditions 4 Dissolved inorganic nitrogen
1 Transparency 1 -
2 Thermal conditions 2 -
Coastal waters
3 Oxygenation conditions 3 Dissolved oxygen concentration
4 Nutrient conditions 4 Dissolved inorganic nitrogen

Table 1.10
Specific pollutants (any pollutant from the list below which is being discharged in significant quantities into the water body)

The WFD also identifies a list of specific pollutants which are discharged in significant quantities
from processes across Europe and which are known to impact on ecological quality:
Organohalogen compounds and substances which may form such compounds in the
(i)
aquatic environment
(ii) Organophosphorous compounds

(iii) Organotin compounds
Substances and preparations, or the breakdown products of such, which have been proved to
(iv) possess carcinogenic or mutagenic properties or properties which may affect steroidogenic,
thyroid, reproduction or other endocrine-related functions in or via the aquatic environment
(v) Persistent hydrocarbons and persistent and bioaccumulable organic toxic substances

(vi) Cyanides
(vii) Metals and their compounds
(viii) Arsenic and its compounds

(ix) Biocides and plant protection products

For good ecological status, the environmental quality standards established for specific pollutants must not be exceeded.
With the exception of ammonia in freshwaters, environmental quality standards for the specific pollutants have been set in
such a way that, where the standards are met, no adverse effects on aquatic plants and animals should occur.

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