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Surface Water: Chemistry

The ECN protocol for surface water chemistry (WC)


Protocol file


Site types that use this protocol


The possible causes and consequences of changes in climate, land use and industrial, urban and agricultural pollution can be expected to be indicated by changes in the physical and chemical composition of water in rivers and streams. These are determined by both biogeochemical processes and by changes in terrestrial or atmospheric inputs. In addition to the major ions (eg Na+, K+, Ca2+, Mg2+, Cl-, SO42--S, alkalinity) which give a measure of the fundamental chemical composition of the water, other variables (eg NH4+-N, NO3--N, PO43--P) are major plant nutrients, whilst yet others (eg Al3+) have chemical states which are pH dependent and are of particular interest where water bodies are undergoing acidification. By measuring concentrations of these ions at frequent and regular intervals, together with water flow, it is possible to calculate loads and fluxes of ions which may be of interest in relation to nutrient budgets.

Weekly dip samples for 15 chemical variables are taken.

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Our field activities


Now that autumn has arrived the ECN fieldwork calendar begins to quieten down. We cease monitoring most terrestrial invertebrates apart from spiders. In rivers and lakes we make the last freshwater invertebrate survey of the year.

See all this month's field measurements...

Wytham in the autumn (fall). Photo: Denise Pallett