Journal of the Mineralogical Society of Korea (한국광물학회지)

The Mineralogical Society of Korea (한국광물학회)
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The Changes of Specific Surface Area of Soils after Peroxidation and Its Implication for the Calculation of Critical toads of Soil Acidification

Peroxidation 전후의 토양 비표면적 변화와 토양산성화 임계부하량 계산에의 의의

  • Yeo, Sang-Jin (School of Earth and Environmental Sciences, Seoul National University) ;
  • Lee, Bumhan (School of Earth and Environmental Sciences, Seoul National University) ;
  • Soyoung Sung (School of Earth and Environmental Sciences, Seoul National University) ;
  • Kim, Soo-Jin (School of Earth and Environmental Sciences, Seoul National University)
  • Published : 2002.09.01
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Abstract

Mineralogy and the exposed surface area are two of the most important factors controlling dissolution and weathering rates of soils. The mixture of inorganic and organic materials of various size distributions and structures that constitute soils makes the calculation of weathering rates difficult. The surface area of soil minerals plays an important role in most of programs for calculating the weathering rates and critical loads. The Brunauer-Emmett-Teller (BET) measurement is recommended for the measurement of specific surface area. However, BET values measured without organic matter removal are in fact those far all the N2-adsorbed surface areas, including the surfaces covered and aggregated with organisms. Surfaces occupied by organisms are assumed to be more reactive to weathering by organic activities. Therefore, the BET surface area difference before and after organic removal depicts the area occupied by organisms. The present study shows that the BET values after organic matter removal using $H_2$O$_2$ are larger than those without removal by 1.68~4.87 $m^2$/g. This implies that BET measurement without organic removal excludes the reactive area occupied by organisms and that the area occupied by organisms in soils is much larger than expected. It is suggested that specific surface area measurement for calculating weathering rates of mineral soils should be made before and after organic matter removal. The results of a column experiment are presented to demonstrate the potential retarding influence that this organic matter may have on mineral dissolution and weathering.

광물조성과 노출표면적(exposed surface area)은 토양풍화속도 계산모델에 영향을 미치는 중요한 요인들이다. PROFILE 등 기존의 풍화속도 계산모델에서는 입도분석자료에 기초한 기하학적 계산값이나 $N_2$-BET 비표면적 등을 그대로 노출표면적으로 적용하고 있다. 그러나, 토양은 광물과 유기물의 혼합체로써 노출표면적을 정확히 구하기는 상당히 어려운 것이 사실이다. 본 연구에서는 유기물의 영향에 의한 토양광물의 노출표면적변화를 토양 깊이에 따른 peroxidation 전후의 N2-BET 비표면적값을 통해 살펴보고, 토양칼럼실험을 이용하여 풍화속도의 차이를 살펴보았다. 실험결과 peroxidation 후의 $N_2$-BET 비표면적은 1.68~4.87 $m^2$/g의 범위에서 증가하였으며, 깊이에 따라 증가하는 범위가 감소하는 경향을 보여주었다 이는 부식산 등 토양표면에 농집되어 존재하는 다양한 형태의 유기산 등이 광물의 노출표면적을 감소시키고 있다는 것을 의미한다고 할 수 있다 기존의 토양풍화속도 모델에서 토양광물 노출표면적변화 계산에 있어서 광물-유기산간의 결합에 의한 영향을 결합세기 측면에서 고려하고 정량화 하는 것이 향후과제라고 생각된다.

Keywords

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