Page 371 - Soil and water contamination, 2nd edition

358 Soil and Water Contamination

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Figure 18.15 Trends in stream water a) pH, and b) SO 4 , and c) NO 3 concentrations in Watershed 6 of the
Hubbard Brook Experimental Forest, New Hampshire, USA, in the period 1963–2010 (source: Gene E. Likens,
personal communication)).
In contrast to the Hubbard Brook Ecosystem Study and other research initiatives,
most national and regional water quality monitoring programmes have been established
to evaluate actual water quality against statutory standards and targets. Data from these
monitoring programmes also provide valuable insight into the long-term evolution of
water quality in response to changing point source and diffuse emissions. For example, the
regular, biweekly monitoring of dissolved nutrients, dissolved oxygen , and chloride at the
main monitoring station in the Dutch reach of the river Rhine near Lobith dates back to

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