Lead reduction and redistribution in the forest floor in New Hampshire northern hardwoods

• Published in: Journal of environmental quality Vol. 33; no. 1; pp. 141 - 148
• Main Authors: Yanai, R.D, Ray, D.G, Siccama, T.G
• Format: Journal Article
• Language: English
• Published: Madison, WI Crop Science Society of America 01.01.2004; American Society of Agronomy
• Subjects: Affinity; Age; Agronomy; altitude; Applied sciences; atmospheric deposition; Atmospherics; Biological and physicochemical properties of pollutants. Interaction in the soil; chemical concentration; Control; Copyrights; Documents; Earth sciences; Earth, ocean, space; Emission measurements; Emissions; Engineering and environment geology. Geothermics; Environmental Monitoring; Environmental quality; Exact sciences and technology; Forest floor; forest litter; forest soils; Forests; Gain; Hampshire; hardwood forests; Hardwoods; Horizon; Humans; Lead; Lead (metal); Lead - metabolism; Mountains; National forests; New Hampshire; Organic matter; Pollutants; Pollution; pollution control; Pollution, environment geology; Reduction; Soil; Soil and sediments pollution; soil horizons; soil organic matter; Soil Pollutants; soil pollution; Stands; Supports; tree age; Trees - metabolism; Vehicle Emissions; New Hampshire; United States; North America; America; United States > US; USA, New Hampshire; USA, Arizona, White Mts; USA, New Hampshire, Hubbard Brook Experimental Forest; Sorption; Deciduous forest; Organic matter; Atmospheric fallout; Pollutant behavior; Soil horizons; Watershed; Lead; Soil interaction; Forest soil; Soil pollution; Heavy metal
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq2004.0141

Because of the affinity of organic matter for lead, atmospheric loadings of this pollutant have been strongly retained in the forest floor. With the regulation of Pb emissions, loadings have decreased. We measured changes in Pb in forest floor horizons at a variety of northern hardwood sites in New Hampshire from the late 1970s to the 1990s. In all seven of the sites in which horizons were distinguished within the forest floor, Pb was found to be declining in the upper (Oie) horizon, but not in the underlying Oa and A horizons. At the Hubbard Brook Experimental Forest (HBEF), this loss from the Oie resulted in a 36% loss of Pb from the forest floor as a whole between 1976 and 1997 (p < 0.001). In contrast, in six stands in the Bartlett Experimental Forest (BEF), losses of Pb averaging >50% from the Oi and Oe horizons (p = 0.01) between 1979 and 1994 were compensated by gains in the Oa and A horizons. Similarly, at seven additional stands in the White Mountain National Forest, changes in the forest floor as a whole from 1980 to 1995 were not statistically significant (redistribution within the forest floor was not evaluated at these sites). Lead concentrations were highest in the Oe or Oie in the 1970s, but were highest in the Oa horizon in the 1990s. There was no significant pattern of Pb loss or retention as a function of stand age across all the sites.