近1500年来古里雅冰芯中NO^3_-浓度变化及其环境意义

Variation and Environmental Implication of Nitrate Concentration in Guliya Ice Core in the Recent 1 500 Years

文章综合分析了古里雅冰芯中ＮＯ－３的各种可能来源，并认为太阳活动、平流层Ｎ２Ｏ的氧化和陆源气团是其主要来源．在近１５００ａ来的ＮＯ－３浓度变化中，存在明显的２３３ａ，８８１ａ，３０ａ，５５ａ和１０４ａ周期，其中２３３ａ，８８１ａ，５５ａ和１０４ａ周期分别与太阳活动的海尔周期、世纪周期、双振动周期和黑子周期相接近或一致，而３０ａ周期与中亚湖泊水位的变化周期相接近．太阳活动是古里雅冰芯中ＮＯ－３浓度变化的主要控制因子，两者的长期变化趋势呈现明显的正相关关系．太阳活动的蒙德尔极小期、施珀雷尔极小期、中世纪极大期和中世纪极小期，在近１５００ａ来该冰芯的ＮＯ－３浓度变化曲线上均有表现．交叉谱分析表明，太阳黑子活动和该冰芯中ＮＯ－３浓度的１１ａ周期变化位相不一致，ＮＯ－３浓度变化滞后于太阳黑子相对数变化约１５ａ左右．

Nitrate(NO-3) in precipitation comes from various sources, which cause many difficulties in understanding its environmental implication. Nevertheless, study of the major sources of NO-3in an ice core can not only recognize its environmental implication, but also interpret its secular variation. By analyses, it is found that solar activity, oxidation of nitrous oxide in the stratosphere and continental air mass ( mainly including crustal dust and content of soluble materials in vapour in air mass) are the major sources of NO-3in the Guliya ice core. Spectral analysis of the variation of NO-3concentration in the recent 1 500 years shows strong periodicities of 233 a, 881 a, 30 a, 55 a and 104 a. Nearly all the periodicities are close to or consistent with solar activity periodicities of 22 a, 80～100 a, 5～6 a and 11 a, except the periodicity at 30 a, which is close to the periodicity of water level variations of lakes in the central Asia, about 31～34 a. Solar activity is a major factor in controlling the variation of NO-3concentration in the ice core. The secular variation of solar activity and NO-3concentration show a remarkable positive correlationship. The Maunder Minimum, Sporer Minimum, Medieval Maximum and Medieval Minimum of solar activity can be seen obviously in the curve of the variation of NO-3 concentration in the Guliya ice core in the recent 1 500 years. By cross spectral analysis, it is found that there is a phase lag, about 1.5 a, between the variation of NO-3 concentration in the ice core and solar activity at the periodicity of 11 a, and the variation of sunspot numbers are in advance.