Hubbard Brook Experimental Forest, annual

Figure 5. Comparison between EUS S02 anc NOx emissions and annual weighted concentrations of SO -, NO3, and NH in bulk deposition at the Hubbard Brook Experimental Forest from 1964 to 1977. Line through emissions is drawn through estimates each five year period from 1965. (From Hidy, 8).

Figure 3 Long-term declines in sulfate concentrations mitigate the mobilization of aluminium in soil solutions and stream water in the Hubbard Brook Experimental Forest, New Hampshire, USAf a-c, annual volume-weighted concentrations of a, inorganic monomeric aluminium (Ah) b, organic monomeric aluminium (Af) and c, sulfate (SO/ ) in mineral soil solutions at 750 m (%) and 730 m (O), and in stream water (triangles)...

Figure 3.2. Annual emissions of sulfur dioxide and nitrogen oxides for the source area of the Hubbard Brook Experimental Forest. The source area was determined by 24-hour back trajectory analysis. Shown are emissions from both U.S. and Canadian sources...

Figure 3.3. Annual volume-weighted sulfate, nitrate, and ammonium concentrations and pH in bulk and wet deposition at the Hubbard Brook Experimental Forest, New Hampshire 1963-2000...

Figure 3.9. Annual volume-weighted stream water sulfate, nitrate, calcium concentrations, pH, and concentrations of total (Aim) and organic dissolved aluminum (Alo) at the reference watershed of the Hubbard Brook Experimental Forest from 1963-2000. Note that dissolved inorganic aluminum is the difference between total and organic dissolved aluminum...

The longest-term experimental study of acid precipitation in the U.S. has been conducted at the U.S. Forest Service Hubbard Brook Experimental Forest in New Hampshire s White Mountains. It is downwind from major U.S. urban and industrial centers and is, therefore, a prime candidate to receive acid precipitation. This is reflected by mean annual pH values ranging from 4.0 to 4.2 during the 1964-74 period. During this period, the annual hydrogen ion input ([H" "] x volume) increased by 36%. 

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