中国农田的温室气体排放   总被引：70，自引：2，他引：70  

李长生  肖向明  S.Frolking  B·Moore Ⅲ  W.Salas  邱建军  张宇  庄亚辉  王效科  戴昭华  刘纪远  秦小光  廖柏寒  R.Sass 《第四纪研究》2003,23(5):493-503

中国是一个农业大国,拥有约1.33百万平方公里的农田。这些田地的种植、翻耕、施肥、灌溉等管理措施不仅长期改变着农田生态系统中的化学元素循环,而且给全球气候变化带来影响。农业生态系统对全球变化的影响主要是通过改变3种温室气体,即二氧化碳(CO₂)、甲烷(CH4)和氧化亚氮(N₂O)在土壤-大气界面的交换而实现的。为了分析多种因素(如气候、土壤质地、农作物品种及各种农田经营管理措施等)对农业土壤释放CO_22222222  相似文献   

Analysis Method for Predicting Strain in Interior Beds and Sub-Resolution Faults from Area Balance Theory in Extensional Basins   总被引：1，自引：0，他引：1  

Groshong Jr R H 《中国地质大学学报(英文版)》2002,13(4)

Extensional basins include mainly grabens and half grabens displaced along a lower detachment. Based on area balance theory, there is a linear relationship between a height of regional and the lower detachment h on the outside of the basin and “lost area S“ from the regional in the basin. The pre-growth beds above lower detachment are of the same extensional displacement so that an “S-h diagram“ can be used to determine the depth to lower detachment and to calculate the total extensional displacement of the beds above the lower detachment. The extensional displacement is dominated by the heave of various scale normal faults. The displacement of obvious faults can be immediately figured out from the measured bed-length. The requisite extension calculated by area balance is the layer-parallel strain, which could be accommodated by displacement on sub-resolution faults. Accordingly, the layer-parallel strain can help us predict the magnitude and distribution of sub-resolution faults on the basis of analysis of the structural style and rheological behavior.  相似文献   

Effects of Biodegradation on the Distribution of Alkylcarbazoles in Crude Oils     

张春明  梅博文  STEVE R.LARTER  MARTIN P.KOOPMANS  肖乾华 《中国地球化学学报》2002,21(2):140-146

We have investigated the distributions of alkylcarbazoles in a series of crude oils with different biodegradation extents, in combination with biomarker parameters, stable carbon isotopic ratios and viscosities. The analyses showed that slight biodegradation has little effect on alkylcarbazoles. The concentrations of C₀-, C₁-, and C₂-carbazoles seem to display a slight decrease with biodegradation through the moderately biodegraded stage, and an abrupt decrease to the heavily biodegraded stage. The relative concentrations of C₀-, C₁-, and C₂-carbazoles do not show any apparent change in the non-heavily biodegraded stages, but through non-heavily biodegraded to heavily biodegraded stages, the percentages of C₀- and C₁-carbazoles decrease, and those of C₂-carbazoles increase significantly, which may indicate that C₂-carbazoles are more resistant to biodegradation than lower homologous species. As to C₂-carbazole isomers, the relative concentrations of the pyrrolic N-H-shielded, pyrrolic N−H partially shielded and pyrrolic N-H-exposed isomers do not show any obvious variation in the non-heavily biodegraded oil, but there is an abrupt change through the mid-biodegraded stage to the heavily biodegraded stage. This project was financially supported by the Youth Knowledge-Innovation Foundation of CNPC (No. 00Z1304).  相似文献   

Analysis of the Statistical Behaviour of Daily Maximum and Monthly Rainfall Data at New Delhi During Monsoon Period     

C. V. Singh  R. S. Adhikari  H. P. Garg 《大气科学进展》2002,19(3):425-432

1．IRt回*CtZOllIndian Summer Monsoon Varlablllty Is a muchdscussed and researched field,yet thereIs a considerable scope IOr further work and It Is understanding．The south—west monsoonwhich contributes more than 75%of the annual ra!nfa!lin a major port!on of Ind!a,Is thespring of!he nallonaleconomy．The ralnmH has Qo sustain山e Increasing needs ofagrlculturelrrlgatlon,the Increasing population and the rapid Industrlallsatlon．It Is lowever noted thatthe monsoon rainfall over differe…  相似文献   

深俯冲和地幔底部P波速度的非球层变化     

R.D.VanderHilst  罗显松 《世界地震译丛》2002,(5):31-44

回顾了与深俯冲和地幔底部结构有关的层析成像的一些新近结果，成像显示出了一些地震波速高于下地幔平均值的狭长结构，它们和上地幔地震板相连续，其地理分布和过去120Ma中板块敛合区出露于地表的位置相关性很强，在大约2000km深处，这些长的线性结构分裂成更小的单元，然而，在一些地区，狭窄的下降体看起来好象是延伸到了地幔底部，在这些地方它们的分散开来形成长波长结构。这样就支持了认为深俯冲和下地幔的复杂结构有关系的预测，上升体似乎没有像下降体那样更普遍地存在，而且所使用的P波数据也成像较差，这些结果证实了很多过去基于残差球谐分析的结果，也和放射性衰减从内部加热而产生的全地幔对流假说一致。尽管有全幔的对流，但对流流动似乎在上地幔过渡带以及在大约1800－2300km深处的过渡带被强烈地扰动，虽然成像未必能反映出因状态变化而引起的深部对流形态的变化，但是P波和S波数据的联合反演表明它和纵波及横波波速之比的变化是一致的，弹性模具的这种表现在其他地方也有报道，这暗示了地幔底部附近广泛存在化学非均匀性，因此地幔底部约800km的区域包含了有助波于我们理解地球构造和演化的信息，不幸的是，我们不能采集到足够多的直达P波数据，但如果使用核震相，则数据覆盖能够得到改善，我们初步的研究认为，虽然本文提出的P波模型解释了大量的已被用于研究核幔边界上部非均匀性的PKP波走时残差，但是却低做了它们的幅度，走时差和直达P波数据的联合反演可望减少波速模型中非均匀性程度的明显偏差，而且它还充分利用了走时残差的优点，而不必假定异常的位置。  相似文献   

Environmental records of carbon in recent lake sediments   总被引：4，自引：0，他引：4  

陈敬安  万国江  汪福顺  D.D.Zhang  黄荣贵  张峰  R.Schmidt 《中国科学D辑(英文版)》2002,45(10):875-884

Based on careful sampling and accurate analysis of recent sediments in Lake Chenghai, this paper discusses the staggered positive/negative correlation between organic carbon (OC) concentration and inorganic carbon (IC) concentration. The result indicates that temperature change, and its induced relative changes are the main factors affecting the relationship between IC concentration, δ¹³C of carbonate and OC concentration. When temperature and its induced photosynthesis strength change control autochthonous calcite precipitation, OC concentration is positively correlated with IC concentration and δ¹³C of carbonate. When temperature and its induced physical/chemical changes dominate, OC concentration displays negative correlation with IC concentration and δ¹³C of carbonate. IC concentration and δ¹³C of carbonate in sediments of Lake Chenghai are good proxies for climatic warm/cold changes.  相似文献   

湖泊现代沉积物碳环境记录研究   总被引：37，自引：3，他引：37  

陈敬安  万国江  汪福顺  黄荣贵  张峰  D.D.Zhang  R.Schmidt 《中国科学D辑》2002,32(1):73-80

通过对云南程海现代沉积物的精细采样和分析, 研究了湖泊沉积物中有机碳与无机碳含量阶段性的正相关和负相关变化. 结果表明, 温度及其引起的相关变化是控制沉积物无机碳含量、碳酸盐δ ¹³C和有机碳含量变化关系的主要因素. 当温度及其引起的光合作用强度变化对湖泊自生碳酸钙沉淀起主导作用时, 沉积物有机碳含量与无机碳含量及碳酸盐δ ¹³C呈正相关变化; 当温度及其引起的蒸发速率等其他物理化学因素变化对湖泊自生碳酸钙沉淀起主导作用时, 沉积物有机碳含量与无机碳含量及碳酸盐δ ¹³C呈负相关变化. 程海沉积物无机碳含量和碳酸盐δ ¹³C是湖区气候冷暖变化的良好代用指标.  相似文献   

华北克拉通周缘中生代造山型金矿床的氮同位素和氮含量记录   总被引：5，自引：0，他引：5  

毛景文  张作衡  王义天  Jia Yiefei  R.Kerrich 《中国科学D辑》2002,32(9):705-716

测试了华北克拉通周缘胶东、小秦岭-熊耳山、西秦岭、北祁连山西段和张宣大型矿集区内几个典型矿床及个别与矿床相关花岗岩中钾长石和绢云母的氮含量和氮同位素组成. 经过与以往地幔岩、花岗岩、变质岩和矿床的氮含量和氮同位素对比, 认为尽管华北克拉通周缘金矿围岩有前寒武纪变质岩、显生宙沉积岩、镁铁质火山岩和花岗岩, 但其氮同位素都显示出与花岗质岩石的密切关系, 此外地幔物质在一定程度上可能参与了成矿系统. 这一结论与以往的氢、氧、碳同位素研究相当吻合.  相似文献   

IMPROVEMENTS OF A DISTRIBUTED HYDROLOGY MODEL DHSVM AND ITS CLIMATOLOGICAL-HYDROLOGICAL OFF-LINE SIMULATIONAL EXPERIMENTS     

WANG Shourong  HUANG Ronghui  DING Yihui  LEUNG. L. R  WIGMOSTA M. S.  VAIL. L. W. 《Acta Meteorologica Sinica》2002,16(3):374-387

The advanced distributed hydrology-soil-vegetation model DHSVM,developed by Wigmostaet al.(1994)is introduced from US Pacific Northwest National Laboratory.To apply DHSVM inChina for the first time some improvements have been made in terms of the basin characteristics:1)to change evapotranspiration model,using the improved Penman-Monteith approach in place ofthe original one;2)to change the model structure,inserting datasets from 4 stations to grid cellsfor each river basin,instead of datasets from one or two stations;3)to develop new hydrology,vegetation and soil parameterization schemes for improving the simulated results,with focus oncalculation and adjustment of 11 parameters,such as soil porosity (?),field capacity θ_(fc),leaf areaindex LAI,stochastic resistance γ_s,among the total 33 parameters.Then the improved DHSVM isdriven by observed datasets for Luanhe River Basin and Sanggan River Basin,respectively.Thesimulated evapotranspiration(ET),runoff,snow water equivalent,water table,soil moisture andpercolation are then gained as DHSVM outputs.The simulated ET shows that the highest peakappears in May or June instead of July or August.This is consistent with the real situations,owing to the improvement of ET model.The simulated runoff process and flood peak are quiteconsistent with the observed ones.The model efficiency values for Luanhe River and SangganRiver Basins are 0.89 and 0.82,respectively,which shows high simulating ability of the modelsystem for both relatively humid and dry basins.  相似文献   

NUMERICAL SIMULATION EXPERIMENTS BY NESTING HYDROLOGY MODEL DHSVM WITH REGIONAL CLIMATE MODEL RegCM2/CHINA     

王守荣  黄荣辉  丁一汇  L.R.LEUNG  M.S.WIGMOSTA  L.W.VAIL 《Acta Meteorologica Sinica》2002,(4)

Based on improvement of a distributed hydrology-soil-vegetation model (DHSVM for short)and its application to North China,a nested regional climatic-hydrologic model system is developedby connecting DHSVM with RegCM2/China.The simulated climate scenarios,including controland 2×CO_2 outputs,are downscaled to 8 stations in Luanhe River and Sanggan River Basins todrive the hydrology model.According to simulation results,under double CO_2 scenarios,annualmean temperature and evapotranspiration will increase 2.8C and 29 mm,respectively;precipitation also increase but with different value for each basin,6 mm for Luanhe River Basinwhile 46 mm for Sanggan River Basin;runoff change for the two basins is different too,27 mmdecrease for Luanhe River Basin while 26 mm increase for Sanggan River Basin.As a result,therunoff in future for Luanhe River Basin and Sanggan River Basin will be 74 mm and 71 mm,respectively,which is approximately a quarter of annual mean runoff(284 mm)of the wholecountry.Total streamflow for the two basins will decrease about 2.5×10~8m~3.All these indicatethat the warm and dry trend will continue in the two river basins under double CO_2 scenarios.Thenested model system,with both climatic and hydrologic prediction ability,could also be applied toother basins in China by parameter adjustment.  相似文献