Advances in Earth Science ›› 2002, Vol. 17 ›› Issue (5): 670-678. doi: 10.11867/j.issn.1001-8166.2002.05.0670

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REVIEW ON WEATHERING RATES IN THE CRUST WEATHERING SYSTEM

XU Hai-jin 1,MA Chang-qian 2   

  1. 1.Graduate School, China University of Geosciences, Wuhan 430074,China;2.Faculty of Earth Science, China University of Geosciences, Wuhan 430074,China
  • Received:2002-01-29 Revised:2002-05-08 Online:2002-12-20 Published:2002-10-01

XU Hai-jin,MA Chang-qian. REVIEW ON WEATHERING RATES IN THE CRUST WEATHERING SYSTEM[J]. Advances in Earth Science, 2002, 17(5): 670-678.

Weathering rates play a significant role in the evolution of geochemistry of the Earth's surface and region environments. The basic theories of calculation of weathering rates are the mass balance and the law of reactions between solutions and minerals. The behavior of the element in weathering is influenced by many factors including weathering of bedrock, atmospheric precipitation, runoff of water, export of biomass and anthropogenic inputs(such as fertilization). Chemical reactions between minerals and solutions contribute to the base cation release rate due to chemical weathering of silicate minerals, and the total specific rate of reaction will be the sum of the rates of the individual reactions. Three key parameters of reactions between solutions and minerals are Acidic Neutral Capacities(ANC). Base Cation/Aluminium ratio(BC/A)and Critical Loads(CL).Methods of calculation of weathering rates mainly include①PROFILE modeling; ②basic cation depletion; ③input-output budget; and ④Stronium isotope ratio. The PROFILE modeling is a steady-stated and integrated soil chemistry model. Weathering rate of a mineral is controlled by dissolvable rate of the mineral, exposed surface area of the mineral. soil moisture saturation and soil layer thickness, and the total weathering rate is obtained by adding the contributions from all minerals. The element depletion is mostly the depletion of base cation such as Ca, Na, K and Mg. In the calculation of weathering rate, it's assumed that Ti,Zr or Nb is resistant, and thus Ti,Zr or Nb is considered to be immobile during weathering. Weathering rate is calculated as the difference between outputs and inputs, provided that the study area is in steady state. In general, the input is considered as the contribution from precipitation, while the output is calculated as the sum of ①river-transported dissolved fraction; ②river-transported suspended non-detrital fraction; and ③biotic nutrient net uptake. It is suggested that Sr isotope is not fractionated during biotic and chemical processes, and Sr isotopic compositions in different ecosystem exchangeable-cation pools ar
e mixtures derived from mineral weathering reactions and atmospheric aerosol.

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