摘要
通过山西汾阳不同植被条件下的对比溶蚀实验,并结合土壤有机碳和无机碳含量测试分析及土壤水分含量和CO2浓度野外现场测试,揭示出北方半干旱条件下的溶蚀速率特征及其影响因素,结果表明:(1)不同植被条件下的土下试片溶蚀速率差异明显,林地的地面以下溶蚀速率最大,为0.551 1mg/(cm2·a),分别是灌丛[0.258 5mg/(cm2·a)]和草地[0.254 7mg/(cm2·a)]的2.13倍和2.16倍;表明随着植被的正向演替,碳酸盐岩溶蚀速率有增加的趋势。(2)试片溶蚀速率主要受土壤有机碳、无机碳、水分控制,受土壤CO2浓度影响小;其中土壤有机碳含量、土壤水分与试片溶蚀速率呈正相关,土壤无机碳含量与试片溶蚀速率呈负相关;高浓度的无机碳使部分试片经过溶蚀后重量不减反增,造成试片溶蚀速率偏低。(3)以林地、灌丛、草地条件下试片土下平均溶蚀速率计算出研究区岩溶碳汇强度为1.815tCO2/(km2·a),与前人根据水化学径流法计算的结果[8.69tCO2/(km2·a)]相比偏小。这意味着由溶蚀试片法来计算我国岩溶碳汇量可能会比实际偏小。
The study area,the Mapao spring,is located in southwest of the Jinzhong basin,Shangxi Province.The Mapao spring catchment has an area of 212.06 km2.Annual air temperature and precipitation in the study area average in 11.11 ℃ and 444.44 mm and the elevation ranges from 1 100 m to 1 900 m,decreasing from west to east and from north to south.The strata exposed in the study area are primarily carbonate rocks （limestone and dolomite） of the Cambrian-Ordovician system.By means of comparison dissolution experiment under different vegetation conditions,testing analysis on the contents of soil organic carbon and soil inorganic carbon,and field measurement for the concentration of soil CO2 and moisture content,the features of the dissolution rate and its impact factors in semiarid conditions in north China are revealed as follows.（1） The tablets dissolution rate,obvious different under different vegetation conditions,is the largest in forest land with the value of 0.551 1 mg/（cm2 · a）,which is 2.13 times,2.16 times higher than that under shrub conditions and meadow land respectively.This result indicates that carbonate dissolution rate has an increas ing tendency along with the positive succession of vegetation.（2） The tablets dissolution rate is mainly affected by soil organic carbon,soil inorganic carbon,soil moisture,but slightly affected by the soil CO2 concentration.The soil organic carbon content and soil moisture is positive related with the tablets dissolution rate,the soil inorganic carbon content is negatively related with the tablets dissolution rate.So,high levels of inorganic carbon can lead to the weight of some tablets increase instead of decrease after a year＇s corro sion,which results in the tablets dissolution rate becomes slower.（3） The karst carbon sink intensity,i.e.1.815 tCO2/（km2 · a）,calculated in light of the average dissolution rate in forest land and shrub land as well as grassland is smaller in comparison with the former figure,i.e.8.69 tCO2/（km2 · a）,calculated in accordance with hydrochemistry-runoff method.This means that the amount of karst carbon sink being calculated by means of dissolution method is likely to be smaller than the actuality.
出处
《中国岩溶》
CAS
CSCD
2013年第3期258-265,共8页
Carsologica Sinica
基金
中国地质调查项目(12120113005200)
国家自然科学基金项目(41302211)
关键词
溶蚀速率
碳汇
土壤有机碳
土壤无机碳
土壤CO2
半干旱岩溶区
dissolution rate
carbon sink
soil organic carbon
soil inorganic carbon
soil CO2
karst area with semiarid environment
