土壤学报2017，Vol.54Issue(1)：1-13,13.DOI:10.11766/trxb201605170194
水耕人为土时间序列铁氧化物与磁化率演变特征
Evolution Characteristics of Iron Oxides and Magnetic Susceptibility in Stagnic Anthrosols along Chronosequences
摘要
Abstract
Objective]The study is oriented to explore characteristics of the evolution of iron oxides and magnetic susceptibility in Stagnic Anthrosols,different in parent material,in subtropical China along chronosequence and their influencing factors. [Method]Soil samples were collected for extraction of total Fe(Fet),free Fe oxides(Fed),amorphous Fe oxides(Feo)and organic-bound Fe(Fep)by the lithium metaborate fusion method,the dithionite-citrate-bicarbonate(DCB)method,acid ammonium oxalate (AAO)at pH=3 in the dark and Na-pyrophosphate at pH=10,separately. Magnetic susceptibility(MS) of the soils was measured at both low(0.47 kHz)and high frequencies(4.7 kHz)using a Bartington MS-2B meter with dual frequency sensor.[Result]Results show that along the chronosequence,weighted mean total Fe(Fet),free Fe oxides(Fed)and Fed/Fet in the 0~120 cm soil layer increased in the calcareous Stagnic Anthrosols,at a rate of 3.2 t hm-2 a-1,1.2 t hm-2 a-1 and 0.04% a-1,respectively,during the first 50 years and at a rate of 0.1 t hm -2 a-1,0.15 t hm-2 a-1 and 0.01% a-1,respectively,during the following 950 years(50~1 000 years),but decreased in the acid Stagnic Anthrosols at a rate of 0.2 t hm -2 a-1, 0.5 t hm-2 a-1 and 0.03% a-1,respectively,during the first 60 years and at a rate of 0.9 t hm-2 a-1,1.2 t hm-2 a-1 and 0.06% a-1 during the following 240 years(60~300 years),while weighted mean amorphous Fe oxides (Feo)and Feo/Fed in the 0~120 cm soil layer tended to decrease in the calcareous Stagnic Anthrosols, but did reversely in the acid Stagnic Anthrosols. Soil pH,Eh,and the balance between input of external Fe with irrigation and loss of internal Fe with leaching are major factors controlling the rates and pathways of Fe oxides transformation during the evolution of Stagnic Anthrosols. Along the chronosequence,the Stagnic Anthrosols derived from calcareous parent material underwent chronosequence demonstrated three phases of magnetic changes,i.e. the initial phase lasting a few decades dominated by rapid decreases in MS(magnetic susceptibility),SIRM(saturation isothermal remanent magnetization)and IRMs(soft isothermal remanent magnetization);the second phase lasting a bit more than two centuries(50~300 years)demonstrating constant IRMh(hard isothermal remanent magnetization)and slow decline in MS,SIRM,and IRMs;and the third phase(300~1 000 years),witnessing minimal changes in MS,SIRM and IRMs but drastic decline in IRMh,while the Stagnic Anthrosols derived from acid parent material did two phases,which in the 0~20 cm soil layer were completely different from those in the 20~120 cm soil layer:In the first phase(0~60 years),MS,SIRM and IRMs declined but IRMh increased rapidly in the 0~20 cm soil layer,while all the magnetic properties declined in the 20~120 cm soil layer;However,in the second phase(60~300 years),all the magnetic properties did not vary much in the 0~20 cm soil layer,while MS,SIRM,and IRMs declined rapidly in the 20~120 cm soil layer after 150 years of paddy cultivation.[Conclusion]The overall magnetic depletion in the Stagnic Anthrosols,though different in parent material was attributed to the reductive dissolution of ferromagnetic minerals under artificial submergence.关键词
水耕人为土/时间序列/铁氧化物/磁化率/成土母质Key words
Stagnic Anthrosols/Chronosequence/Iron oxides/Magnetic susceptibility/Parent material引用本文复制引用
黄来明,邵明安,陈留美,韩光中,张甘霖..水耕人为土时间序列铁氧化物与磁化率演变特征[J].土壤学报,2017,54(1):1-13,13.基金项目
国家自然科学基金国际合作与交流项目（41571130051）和土壤与农业可持续发展国家重点实验室开放基金项目（Y20160003）资助 Supported by the Projects of International Cooperation and Exchanges，National Natural Science Foundation of China（No.41571130051）and Project from State Key Laboratory of Soil and Sustainable Agriculture （）
