亚热带花岗岩地区土壤矿物风化过程中盐基离子的释放特征
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摘要
矿物风化过程中盐基离子释放遵从一定的化学计量关系,这种化学计量关系一般只能通过模拟实验来获取。本研究采用pH 7.0的EDTA-乙酸铵溶液将土壤中的交换性盐基离子完全洗脱出来,然后用Batch方法模拟不同pH溶液淋溶洗脱盐基和未洗脱盐基土壤,旨在消除土壤中交换性盐基离子的影响后更为准确地判断土壤矿物风化的盐基离子释放特征。结果表明:未洗脱盐基土壤的淋出液pH由3.73±0.14逐渐上升到4.23±0.06,主要原因是淋溶液中有高浓度的NH_4~+;洗脱盐基土壤矿物风化后淋出液pH从7.39±0.02逐渐下降到5.39±0.17,主要是由于土壤中可风化矿物减少。土壤交换性盐基离子会改变盐基离子释放特征、释放总量:未洗脱盐基土壤经酸雨淋溶后,各盐基离子释放均呈现急速下降后逐渐平缓的趋势,洗脱盐基土壤矿物风化后,K~+及盐基离子释放总量呈波动上升趋势,且盐基离子释放总量比未洗脱盐基土壤低。土壤交换性盐基离子的存在还会改变淋出液中的盐基离子化学计量关系:未洗脱盐基土壤的K~+︰Ca~(2+)︰Mg~(2+)︰Na+化学计量关系为11︰13︰4︰1(当量比),而洗脱盐基土壤为7︰2︰2︰1。K~+是盐基离子中风化释放量最多的,大部分K~+来自于土壤中云母的风化。因此,只有利用洗脱盐基土壤的盐基离子释放量才能准确计算矿物风化速率并获得准确的化学计量关系。土壤矿物风化作用随着淋溶液酸度增大而增强,但模拟一年降雨量的情况下,p H 3.5、4.5和5.5三种不同p H溶液对矿物风化后盐基离子的释放在实验期间没有显著性影响,较长时间后的差异性有待观察。本研究表明,可以通过预洗脱盐基土壤然后模拟酸雨淋溶的方法,观察矿物风化特征,特别是盐基离子释放的化学计量特征。
Release of base cations follow a stoichiometric relationship during soil mineral weathering, and the stoichiometric relationship can only be obtained through simulated experiments. EDTA-ammonium acetate solution at p H 7.0 was used to remove soil base cations(here called treated soil), and then the batch method was used to simulate leaching at different p H values in treated and untreated soils. The release characteristics of base cations from the soils were then investigated during soil mineral weathering. Results showed that leaching solution p H of the untreated soil raised from 3.73±0.14 to 4.23±0.06, attributed to high concentration of NH4+ in the leaching solution. Decrease of the easily weathering minerals reduced the leaching solution p H from 7.39±0.02 to 5.39±0.17 of treated soil during leaching experiment. Exchangeable base cations of the untreated soil could change the release characteristics and release amount of base cations. Base cations in leaching solution declined firstly, and then remained stable. However, K~+ and total base cations increased with time in the leaching solution for the treated soil. The total release amount of base cations was lower for the treated soil than that for untreated soil. Soil exchangeable base cations could change the stoichiometric relationship of base cations in leaching solution. The ratio of K~+︰Ca~(2+)︰Mg~(2+)︰Na+ was 11︰13︰4︰1(equivalent charge) in the leaching solution for the untreated soil, while it was 7︰2︰2︰1 for the treated soil. The release amount of K~+ was greater than other base cations and most of K~+ released came from weathering of mica. Therefore, the soil with base cations removed can be used to estimate mineral weathering rate more accurately and to obtain the accurate base cations stoichiometric relationship. The more acids in the leaching solutions led to more release of base cations, and stronger mineral weathering in the soil. At p H 3.5, 4.5 and 5.5, the difference of the release of base cations among different leaching treatments was not significant during one-year leaching experiment. The effect of solution p H needs to be studied further by long-term leaching experiment. This study suggested that the leaching treatments with simulating acid rain to the soil with base cations removed could be used to study the mineral weathering characteristics and stoichiometric characteristics of base cations released from soils.
Release of base cations follow a stoichiometric relationship during soil mineral weathering, and the stoichiometric relationship can only be obtained through simulated experiments. EDTA-ammonium acetate solution at p H 7.0 was used to remove soil base cations(here called treated soil), and then the batch method was used to simulate leaching at different p H values in treated and untreated soils. The release characteristics of base cations from the soils were then investigated during soil mineral weathering. Results showed that leaching solution p H of the untreated soil raised from 3.73±0.14 to 4.23±0.06, attributed to high concentration of NH4+ in the leaching solution. Decrease of the easily weathering minerals reduced the leaching solution p H from 7.39±0.02 to 5.39±0.17 of treated soil during leaching experiment. Exchangeable base cations of the untreated soil could change the release characteristics and release amount of base cations. Base cations in leaching solution declined firstly, and then remained stable. However, K~+ and total base cations increased with time in the leaching solution for the treated soil. The total release amount of base cations was lower for the treated soil than that for untreated soil. Soil exchangeable base cations could change the stoichiometric relationship of base cations in leaching solution. The ratio of K~+︰Ca~(2+)︰Mg~(2+)︰Na+ was 11︰13︰4︰1(equivalent charge) in the leaching solution for the untreated soil, while it was 7︰2︰2︰1 for the treated soil. The release amount of K~+ was greater than other base cations and most of K~+ released came from weathering of mica. Therefore, the soil with base cations removed can be used to estimate mineral weathering rate more accurately and to obtain the accurate base cations stoichiometric relationship. The more acids in the leaching solutions led to more release of base cations, and stronger mineral weathering in the soil. At p H 3.5, 4.5 and 5.5, the difference of the release of base cations among different leaching treatments was not significant during one-year leaching experiment. The effect of solution p H needs to be studied further by long-term leaching experiment. This study suggested that the leaching treatments with simulating acid rain to the soil with base cations removed could be used to study the mineral weathering characteristics and stoichiometric characteristics of base cations released from soils.
引文
[1]杨金玲,张甘霖,黄来明.典型亚热带花岗岩地区森林流域岩石风化和土壤形成速率研究[J].土壤学报,2013,50(2):253–259
[2]Forsius M,Kleemola S,Starr M,et al.Ion mass budgets for small forested catchments in Finland[J].Water,Air,and Soil Pollution,1995,79:19–38
[3]段雷,郝吉明,叶雪梅,等.中国土壤风化速率研究[J].环境科学学报,2000,20(增刊):1–7
[4]岑慧贤,王树功,仇荣亮.模拟酸雨对土壤盐基离子的淋溶释放影响[J].环境污染与防治,2001,23(1):12–15
[5]Yang J L,Zhang G L,Huang L M,et al.Estimating soil acidification rate at watershed scale based on the stoichiometric relations between silicon and base cations[J].Chemical Geology,2013,337–338:30–37
[6]Zhu C,Lu P.Alkali feldspar dissolution and secondary mineral precipitation in batch system:3.Saturation states of product minerals and reaction paths[J].Geochemica et Cosmochimica Acta,2000,73:3171–3200
[7]Fu Q,Lu P,Konishi H,et al.Coupled aalkali-feldspar dissolution and secondary mineral precipitation in batch systems:1.New experiments at 200℃and 300 bars[J].Chemical Geology,2009,258:125–135
[8]鲁如坤.土壤农业化学分析方法[M].北京:中国农业科技出版社.1999.
[9]向廷生,蔡春芳,付华娥.不同温度、羧酸溶液中长石溶解模拟实验[J].沉积学报,2004,22(4):597–602
[10]莫彬彬,连宾.长石风化作用及影响因素分析[J].地学前缘,2010,17(3):281–289
[11]刘俐,宋存义,李发生.模拟酸雨对红壤中硅铝铁释放的影响[J].环境科学,2007,28(10):2 376–2 382
[12]王代长,蒋新,卞永荣,等.模拟酸雨对不同土层酸度和K+淋失规律的影响[J].环境科学,2003,24(2):30–34
[13]孙本华,胡正义,吕家珑,等.模拟氮沉降下南方针叶林红壤的养分淋溶和酸化.应用生态学报,2006,17(10):1 820–1 826
[14]刘俐,周友亚,宋存义,等.模拟酸雨淋溶下红壤中盐基离子释放及缓冲机制研究[J].环境科学研究,2008,21(2):49–55
[15]凌大炯,章家恩,黄倩春,等.模拟酸雨对砖红壤盐基离子迁移和释放的影响.土壤学报,2007,44(3):446–450
[16]于天仁,陈志诚.土壤发生中的化学过程[M].北京:科学出版社.1990
[17]罗家贤,马毅杰,杨德勇,等.过渡性土壤的矿物风化和演变[J].土壤,1994,26(5):241–247
[18]Berner R A,Holdren G R.Mechanism of feldspar weathering:Some observational evidence[J].Geology,1979,5:369–372
[19]王改兰,段建南.土壤矿物钾活化途径[J].土壤通报,2004,35(6):802–805
[20]李福春,李莎,杨用钊,等.原生硅酸盐矿物风化产物的研究进展——以云母和长石为例[J].岩石矿物学杂志,2006,25(5):440–448
[21]黄昌勇.土壤学[M].北京:中国农业出版社.2000
[22]Bain D C,Roe M J,Duthie D M L,et al.The influence of mineralogy on weathering rates and processed in an acid-sensitive granitic catchment[J].Applied Geochemistry,2001,16:931–937
[23]徐仁扣.土壤酸化及其调控研究进展[J].土壤.2015,47(2):238–244
[2]Forsius M,Kleemola S,Starr M,et al.Ion mass budgets for small forested catchments in Finland[J].Water,Air,and Soil Pollution,1995,79:19–38
[3]段雷,郝吉明,叶雪梅,等.中国土壤风化速率研究[J].环境科学学报,2000,20(增刊):1–7
[4]岑慧贤,王树功,仇荣亮.模拟酸雨对土壤盐基离子的淋溶释放影响[J].环境污染与防治,2001,23(1):12–15
[5]Yang J L,Zhang G L,Huang L M,et al.Estimating soil acidification rate at watershed scale based on the stoichiometric relations between silicon and base cations[J].Chemical Geology,2013,337–338:30–37
[6]Zhu C,Lu P.Alkali feldspar dissolution and secondary mineral precipitation in batch system:3.Saturation states of product minerals and reaction paths[J].Geochemica et Cosmochimica Acta,2000,73:3171–3200
[7]Fu Q,Lu P,Konishi H,et al.Coupled aalkali-feldspar dissolution and secondary mineral precipitation in batch systems:1.New experiments at 200℃and 300 bars[J].Chemical Geology,2009,258:125–135
[8]鲁如坤.土壤农业化学分析方法[M].北京:中国农业科技出版社.1999.
[9]向廷生,蔡春芳,付华娥.不同温度、羧酸溶液中长石溶解模拟实验[J].沉积学报,2004,22(4):597–602
[10]莫彬彬,连宾.长石风化作用及影响因素分析[J].地学前缘,2010,17(3):281–289
[11]刘俐,宋存义,李发生.模拟酸雨对红壤中硅铝铁释放的影响[J].环境科学,2007,28(10):2 376–2 382
[12]王代长,蒋新,卞永荣,等.模拟酸雨对不同土层酸度和K+淋失规律的影响[J].环境科学,2003,24(2):30–34
[13]孙本华,胡正义,吕家珑,等.模拟氮沉降下南方针叶林红壤的养分淋溶和酸化.应用生态学报,2006,17(10):1 820–1 826
[14]刘俐,周友亚,宋存义,等.模拟酸雨淋溶下红壤中盐基离子释放及缓冲机制研究[J].环境科学研究,2008,21(2):49–55
[15]凌大炯,章家恩,黄倩春,等.模拟酸雨对砖红壤盐基离子迁移和释放的影响.土壤学报,2007,44(3):446–450
[16]于天仁,陈志诚.土壤发生中的化学过程[M].北京:科学出版社.1990
[17]罗家贤,马毅杰,杨德勇,等.过渡性土壤的矿物风化和演变[J].土壤,1994,26(5):241–247
[18]Berner R A,Holdren G R.Mechanism of feldspar weathering:Some observational evidence[J].Geology,1979,5:369–372
[19]王改兰,段建南.土壤矿物钾活化途径[J].土壤通报,2004,35(6):802–805
[20]李福春,李莎,杨用钊,等.原生硅酸盐矿物风化产物的研究进展——以云母和长石为例[J].岩石矿物学杂志,2006,25(5):440–448
[21]黄昌勇.土壤学[M].北京:中国农业出版社.2000
[22]Bain D C,Roe M J,Duthie D M L,et al.The influence of mineralogy on weathering rates and processed in an acid-sensitive granitic catchment[J].Applied Geochemistry,2001,16:931–937
[23]徐仁扣.土壤酸化及其调控研究进展[J].土壤.2015,47(2):238–244