Evaluating controlling factors to Al(i)/(Ca + Mg) molar ratio in acidic soil water, southern and southwestern China: multivariate approach.
Al(i)/(Ca + Mg) molar ratio in soil water has been used as an indicator to the effects of acid deposition on terrestrial ecosystems. However, the main factors controlling this ratio have not been well documented in southern and southwestern China. In this study, we presented the variation in inorganic aluminum (Al(i)) and Al(i)/(Ca + Mg) molar ratio in different sites and soil horizons based on two to three years monitoring data, and evaluated the main factors controlling Al(i)/(Ca + Mg) molar ratio using principle component analysis (PCA) and partial least square (PLS) regression. Monitoring data showed although Al(i)/(Ca + Mg) molar ratios in most soil water were lower than assumed critical 1.0, higher molar ratios were found in some soil water at TSP and LXH site. Besides acid loading, both soil properties and soil water chemistry affected the value of Al(i)/(Ca + Mg) molar ratio in soil water. Partial least square (PLS) indicated that they had different relative importance in different soil horizons. In A-horizon, soil aluminum saturation (AlS) had higher influence on Al(i)/(Ca + Mg) molar ratio than soil water chemistry did; higher soil aluminum saturation (AlS) led to higher Al(i)/(Ca + Mg) molar ratio in soil water. In the deeper horizons (i.e., B(1)-, B(2)- and BC-horizon), inorganic aluminum (Al(i)) in soil water had more and more important role in regulating Al(i)/(Ca + Mg) molar ratio. On regional scale, soil aluminum saturation (AlS) as well as cation exchange capacity (CEC) was the dominant factor controlling Al(i)/(Ca + Mg) molar ratio. This should be paid enough attention on when making regional acid rain control policy in China.
Guo
Jing-Heng
JH
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 100085 Beijing, China. jh_guo1972@yahoo.com
Zhang
Xiao-Shan
XS
Vogt
Rolf D
RD
Xiao
Jin-Song
JS
Zhao
Da-Wei
DW
Xiang
Ren-Jun
RJ
Luo
Jia-Hai
JH
D000143:Acids / Q000032:analysis*; D000535:Aluminum / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry*; D002681:China; D005618:Fresh Water / Q000032:analysis*; D008274:Magnesium / Q000737:chemistry*; D012987:Soil
D000143:Acids; D012987:Soil; D000535:Aluminum; D008274:Magnesium; D002118:Calcium