半干旱草原温室气体排放/吸收与环境因子的关系研究

静态箱—气相色谱法对内蒙古半干旱草原连续两年的实验观测研究结果表明，内蒙古草原是大气CO2和N2O的排放源，和CH4的汇。在植物生长不同季节，草原生态系统排放／吸收温室气体CO2、CH4和N2O的日变化形式各有不同，其中在植物生长旺季日变化形式最具特征。三种温室气体的季节排放／吸收高峰主要出现在土壤湿度较大的春融期和降雨较为集中时期。对所有草原植物生长季节，CO2净排放日变化形式均为白天出现排放低值，夜间出现排放高值。较高的温度有利于CO2排放，地上生物量决定着光合吸收CO2量值的高低。影响半干旱草原吸收CH4和排放N2O日变化形式的关键是土壤台水量和供氧状况，日温变化则主要影响日变化强度。吸收CH4和排放N2O的季节变化与土壤湿度季节变化分别呈线性反、正相关，相关系数均在0．4-0．6之间。自由放牧使CO2、N2O和CH4交换速率日较差降低，同时使N2O和CH4年度排放／吸收量减少和CO2年度排放量增加。     

Nitrogen and Oxygen Isotope Balance in Tropospheric N2O—An Improved Budget

In steady state the stable isotopic composition of nitrogen and oxygen in tropospheric N2O is balanced by isotopically light N2O emitted from soils and oceans and isotopically heavy N2O as a return flux from the stratosphere.However,no such balance was reached in calculations given by Kim and Caig(1993).Modifications have been made on their calculations based on the most recent reports on annual global emission of N2O.It is considered that the nitrogen and oxygen isotope budget in tropospheric N2O are approximately in balance if isotopic fractionation effects during the production of N2O in soils and furthermore this paper puts forward further evidence for validating the above results.     

Summertime Surface N2O Concentration Observed on FildesPeninsula Antarctica： Correlation with TotalAtmospheric O3 and Solar Activity

Three-year summertime surface atmospheric N2O concentrations were observed for the first timeon the Fildes Peninsula, maritime Antarctica, and the relationships among the N2O concentration, totalatmospheric O3 amount, and sunspot number were analyzed. Solar activity had an important effecton surface N20 concentration and total O3 amount, and increases of sunspot number were followed bydecreases in the N2O concentration and total O3 amount. A corresponding relationship exists betweenthe N2O concentration and total atmospheric O3, and ozone destruction was preceded by N2O reduction.We propose that the extended solar activity in the Antarctic summer reduces the stratospheric N2O byconverting it into NOx, increases the diffusion of N2O from the troposphere to the stratosphere, decreasesthe surface atmospheric N2O, and depletes O3 via the chemical reaction between O3 and NOx. Ourobservation results are consistent with the theory of solar activity regarding the formation of the AntarcticO3 hole.     

内蒙古典型草原N2O研究刍议

利用中国科学院内蒙古草原生态定位研究站（ＩＭＧＥＲＳ）的气候、土壤、植被、土地利用方式和家畜等方面的资料,根据目前国际上Ｎ２Ｏ的研究进展,分析了内蒙古典型草原区影响Ｎ２Ｏ收支作用的可能控制因子,认为：（１）作为Ｎ２Ｏ主要来源的土壤,其理化性状,尤其是土壤温度、水分状况、土壤有机质和土壤结构等,是影响该地区Ｎ２Ｏ收支平衡的主要控制因子;（２）土地利用方式的改变对Ｎ２Ｏ的释放的影响还不十分清楚。草场农用与一定的耕作管理措施以及对天然草场的人为影响（割草、放牧等）是对Ｎ２Ｏ收支平衡影响的主要方面;（３）家畜排泄物,无论作为本地区的主要燃料,还是作为肥料,在典型草原区Ｎ２Ｏ的释放中起着不可忽视的作用。