Bear Brook Watershed

David, M., G. Vance, and J. Kahl. 1999. Chemistry of dissolved organic carbon at Bear Brook watershed, Maine Stream water response to (NH4)2S04 additions. Environmental Monitoring and Assessment 55 149-163. 

Norton, S., J. Kahl, I. Fernandez, T. Haines, L. Rustad, S. Nodvin, J. Scofield, T. Strickland, H. Erickson, P. Wiggington, and J. Lee. 1999. The Bear Brook Watershed, Maine (BBWM), USA. Environmental Monitoring and Assessment 55 7—51. 

Postek KM, Driscoll CT, Kahl JS, et al. 1995. Changes in the concentrations and speciation of aluminum in response to an experimental addition of ammonium sulfate to the Bear Brook watershed, Maine, U.S.A. Water Air Soil Pollut 85 1733-1738. 

Figure 7 High frequency sample variability for Ca and Mg in a stream at Bear Brook Watershed, Maine, USA (S. A. Norton, unpublished).

Fernandez 1. J., Rustad L. E., Norton S. A., Kahl J. S., and Cosby B. J. (2003) Experimental acidification causes soil base cation depletion at the Bear Brook Watershed in Maine. Soil Sci. Soc. J. (in press). 

S., Scofield J., StricklandT., Erickson H., Wigington P., and Lee J. (1999) Nitrogen and sulfur input-output budgets in the experimental and reference watersheds, bear brook watershed in Maine (BBWM). Environ. Monitor Assess. 55, 113-131. 

Norton S. A. and Fernandez I. J. (eds.) (1999) The Bear Brook Watershed in Maine A Paired Watershed Experiment—the First Decade (1987-1997). Kluwer, Dordrecht, 250p. 

Norton S. A. and Kahl J, S. (2000) Impacts of marine aerosols on surface water chemistry at bear brook watershed, Maine. Verh. In. Ver. Limnol. 27, 1280-1284. 

Kinetics of chemical weathering are important to understand the rates of rock dissolution, sediment formation, and acid neutralization in the environment. In this chapter, there are three principal objectives (1) to describe the theoretical kinetics of chemical weathering for pure minerals, (2) to discuss the relative advantages and disadvantages of various experimental apparatus for measuring those kinetics in soils, and (3) to make comparisons between laboratory and field measurements of weathering rates and solute transport. A case study of laboratory and field measurements at Bear Brook Watershed, east of Orono, Maine, at Lead Mountain, will be used to illustrate the principles discussed in this chapter. 

Most experiments on chemical weathering have been performed on pure minerals under carefully controlled laboratory conditions. However, under natural conditions in the field, mixtures of minerals of different abundances are reacting simultaneously, together with amorphous material and organic material subject to ion exchange in soils and sediments. It is instructive to conduct experiments on natural soils in the laboratory and then to compare these results with small plot experiments in the field and the prototype watershed. The site of Bear Brook Watershed at Lead Mountain, Maine (latitude 44 51 75", longitude 68 6 25") is shown in Figure 8. It contains two almost... 

TABLE 1. Elemental Analyses of Soil Samples from Bear Brook Watershed, Maine, by X-Ray Fluorescence and SEM/EDX Microprobe Surface Analyses (% by wt)... 

Figure 15. Bear Brooks Watershed Dissolved Silica. Silica concentrations were slightly higher in West Bear Brook. Highest concentrations occurred during base flow periods when groundwater was contributing most of the water to the streams. Dissolved silica decreased during snowmelt and runoff events due to dilution by new water.

The silica release rate and flow-rate mass ratio of Figure 18 depend on estimations of the wetted surface area of reacting minerals and the mass of wetted soil. As discussed by Paces (1983), there is much uncertainty in estimating wetted surface areas of reacting minerals. In Figure 18 and Table 3, it was assumed that 40% of the surface area of soil was weatherable minerals the soil surface area was 0.5 m2 g 1 (except at Coweeta, where Velbel s (1985) procedure was used), the bulk density of the soil was 1.5 kg L-1, and the equivalent saturated water depth was 0.5 m (except at Coweeta and Cristallina, where it was taken to be 0.1 m). All of these parameters were measured at Bear Brook Watershed and applied to the other sites. 

Results of a field study at Bear Brook Watershed, Maine, were compared with laboratory kinetic experiments using size-fractionated soils from the same location. It is a forested, glaciated region with thin podzolic soils and granitic gneiss bedrock. Fractional order dependence (m = 0.5) of weathering rales on H 1... 

Magill, A. H., Downs, M.R., Nadelhoffer, K.J., Hallett, R.A. and Aber, J.D. (1996). Forest ecosystem response to four years of chronic nitrate and sulfate additions at Bear Brooks Watershed, Maine, USA. Forest Ecology and Management, 84, 29-37. 

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