Nezat et al.(2004)による〔『Influence of landscape position and vegetation on long-term weathering rates at the Hubbard Brook Experimental Forest, New Hampshire, USA』(3065p)から〕

『米国ニューハンプシャー州のハバード・ブルック実験林における長期風化速度に対する地形の状態と植生の影響』


Abstract
 The spatial variability of long-term chemical weathering in a small watershed was examined to determine the effect of landscape position and vegetation. We sampled soils from forty-five soil pits within an 11.8-hectare watershed at the Hubbard Brook Experimental Forest, New Hampshire. The soil parent material is a relatively homogeneous glacial till deposited 〜14,000 years ago and is derived predominantly from granodiorite and pelitic schist. Conifers are abundant in the upper third of the watershed while the remaining portion is dominated by hardwoods. The average long-term chemical weathering rate in the watershed, calculated by the loss of base cations integrated over the soil profile, is 35 meq m-2 yr-1−similar to rates in order 〜10 to 15 ka old soils developed on granitic till in temperate climates. The present-day loss of base cations from the watershed, calculated by watershed mass balance, exceeds the long-term weathering rate, suggesting that the pool of exchangeable base cations in the soil is being diminished. Despite the homogeneity of the soil parent material in the watershed, long-term weathering rates decrease by a factor of two over a 260 m decrease in elevation. Estimated weathering rates of plagioclase, potassium feldspar and apatite are greater in the upper part of the watershed where conifers are abundant and glacial till is thin. The intra-watershed variability across this small area demonstrates the need for extensive sampling to obtain accurate watershed-wide estimates of long-term weathering rates.』

1. Introduction
2. Setting
3. Sampling and analytical methods
4. Results
 4.1. Physical and chemical properties of soils
 4.2. Estimates of chemical weathering
  4.2.1. Titanium variability
  4.2.2. Elemental depletion factors
  4.2.3. Long-term weathering rates
5. Discussion
 5.1. Weathering variability with depth and landscape position
 5.2. Long-term weathering rates
 5.3. Present-day weathering rates and cation losses
 5.4. Mineral weathering rates
  5.4.1. Plagioclase
  5.4.2. Apatite
  5.4.3. Biotite
  5.4.4. Potassium feldspar
 5.5. Spatial variation of weathering
6. Conclusions
Acknowledgments
References


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