玛曲高寒草甸夏季近地层微气象和CO2通量特征分析

利用2015年夏季玛曲高寒草甸观测资料,从中选取7月10个连续完整的观测日,分析了近地层气象要素、地表辐射和能量传输以及CO₂通量日变化特征。结果表明：夏季玛曲地区气温和比湿昼夜差异较大,最大温差为19.2 ℃,平均风速为2.7 m?s^-1,风向以东风为主。晴天条件下向下短波辐射可达1 200 W?m^-2左右,平均地表反照率为0.22,均大于藏北那曲地区。净辐射峰值可达850 W?m^-2左右,陆-气间能量传输以潜热输送为主。10 d能量闭合度平均值为0.61,能量不平衡程度较大。夏季玛曲高寒草甸表现为“碳汇”,CO₂通量平均值为-0.20 mg?m^-2?s^-1,晴天碳吸收最大速率为-14.05 mg?m^-2?s^-1,显著大于阴天,最大碳吸收时长为13 h,CO₂密度平均值为530.7 mg?m^-3。     

土壤改良对土壤水水化学及碳酸盐岩溶蚀的CO2净消耗量的影响

为研究利用滤泥与不同有机肥搭配对岩溶土壤进行改良增加无机碳汇的最佳实施方案,在果化示范区开展了滤泥、滤泥+秸秆+沼液和滤泥+秸秆+牛粪等三种土壤改良方案试验,在各个改良地和对照地埋放标准溶蚀试片和土壤水收集器,测试一年试片溶蚀速率和不同月份土壤水主要阴阳离子浓度。结果表明:滤泥中含有大量钙盐和硫酸盐,导致土壤水类型为Ca-SO4。各个改良地和对照地土壤水中参与岩溶作用的[Ca2+ +Mg2+ ]/HCO3-（当量浓度）均大于1,表明外源酸参与了土壤中碳酸盐岩溶蚀。施肥高峰期,试验区本底土壤CO2净消耗量出现负值,原因是硝化作用产生的H+与土壤水中HCO3-发生脱气作用,导致CO2从水中逸出。单施滤泥改良后,滤泥有机酸显著提高了试片溶蚀速率,但土壤水pH值降低,H+的大量存在导致脱气作用加剧,年均碳酸贡献率为-0.32,年均减少CO2净消耗量0.66 mmol·L-1。滤泥配施秸秆和牛粪引起8月脱气作用加剧,其他月份同样削弱了脱气作用,最终导致CO2年均净消耗量几乎不变。滤泥配施秸秆和沼液大大削弱了单施滤泥引起的脱气作用,同时减小了土壤中碳酸盐岩溶蚀速率的增强程度,最终导致CO2年均净消耗量增加了0.065 mmol·L-1,该方案为最佳增加无机碳汇的实施方案。      

Petrogenesis and tectonic significance of mafic-ultramafic rocks from southwestern Yunnan,China

This study focuses on the mafic-ultramafic lavas of the Early Carboniferous outcrop in Mangxin, southwestern Yunnan, China. Picrites with 26–32 wt% MgO and a quenched texture are the most significant components of this rock association. This article divides the Mangxin picrites into two types. The mantle potential temperature (T_p) of these picrites is higher than the T_p range of mid-ocean ridges and reaches that of mantle plumes. According to their geochemical characteristics, type-1 picrites probably formed from the melting of the mantle plume head and were contaminated by the ambient depleted mantle, whereas type-2 picrites formed from the melting of mantle plume tails. These plume-related mafic-ultramafic rocks in Mangxin and the ocean island basalt (OIB)-carbonate rock associations in many areas of the Changning–Menglian belt provide significant evidence for the improvement of previous models of the Palaeotethyan oceanic plateau.     

Fluid-mineral equilibria in prehnite-pumpellyite to greenschist facies metabasites near Flin Flon, Manitoba, Canada: implications for petrogenetic grids

A sequence of regional metamorphic isograds indicating a range from prehnite-pumpellyite to lower amphibolite facies was mapped in metabasites near Flin Flon, Manitoba. The lowest grade rocks contain prehnite + pumpellyite and are cut by younger brittle faults containing epidote + chlorite + calcite. Isobaric temperature- X _CO2 and pressure-temperature (constant X _CO2) diagrams were calculated to quantify the effects of CO₂ in the metamorphic fluid on the stability of prehnite-pumpellyite facies minerals in metabasites containing excess quartz and chlorite. Prehnite and, to a lesser extent, pumpellyite are stable only in fluids with X _co2 <0.002. For X _co2>0.002, epidote + chlorite + calcite assemblages are stable. Our calculated phase relations are consistent with regional metamorphism in the Flin Flon area in the presence of an H₂O-rich fluid and a more CO₂-rich fluid in the later fault zones. We believe that the potential effects of small amounts of CO₂ in the metamorphic fluid should be assessed when considering the pressure-temperature implications of mineral assemblages in low-grade metabasites.     

南大洋二氧化碳源汇分布及其海-气通量研究

在 1 999年 1 2月 - 2 0 0 0年 2月“雪龙”号科学考察船往返于中山站和长城站期间 ,进行了大气及海表层 CO2 分压的连续测量。研究结果表明 ,在 80°W- 0°- 80°E之间 ,南大洋基本上是大气 CO2 的汇 ,尤其在 45°W- 3 0°W及 1 0°W- 1 0°E之间 ,是 CO2 的强汇区 ,往返的两次观测结果十分相似。观测发现 ,南大洋 1月份吸收大气 CO2 的能力近两倍于 1 2月份 ,这是由于该海域1月的生产力比 1 2月份高 ,因而反映了初级生产对大气 CO2 吸收的显著影响。利用最新的 K值计算方法表明 ,1月份二氧化碳的入海通量为 3 .98mol/(m2 · a) ,1 2月份的为2 .1 3 mol/(m2 · a) ,综合两个月的值平均 ,南大洋夏季 CO2 的平均通量为 3 .0 6 mol/(m2 · a) ,是南半球夏季一个重要的汇区     

迎接地球科学的春天

通过水化学、碳稳定同位素和碳酸盐沉积物沉积速率的对比分析 ,发现在贵州乌江渡坝址灌浆廊道中存在两种不同类型的碳酸盐沉积物 ,即 :放CO2 型和吸CO2 型。前者如通常岩溶洞穴中所见 ,是天然条件下岩溶作用的产物 ;而后者则很特殊 ,它是灌浆帷幕和混凝土发生碳酸盐化的结果。由于碳酸盐化时自大气迅速吸入CO2 ,使得廊道中CO2 浓度降低 ,并每年可产生高达 10cm的碳酸盐沉积物。考虑到世界范围内水泥的大量使用 ,水泥或混凝土碳酸盐化的环境意义 ,即在全球碳循环的研究中对大气CO2 沉降的贡献是不容忽视的。据初步估算 ,该碳贡献量每年约 1亿t左右。     

Distribution of CO_2 in Soil Air Affected by Vegetation in the Shilin National Park

This paper studies the CO2 distribution of soil atmosphere in the Shilin National Park. The measurement sites were chosen according to different topographic features and different vegetations. Seven measurement sites on 3 cross sections were chosen to pass through 3 karstic depressions or on the slopes of depressions. All measurement results show soils with pH values lower than 7.0 (from 5.4 to 6.6). There are 2 cases for the pH values of soil in different topographic features: the pH values of 2 profiles on the ridges or upper slopes of depressions are lower than those in the depressions; and the pH values of 2 soil profiles on the slopes of depressions are higher than those in the depressions. Most samples show relatively low humidity and CO2 contents on the ridges or slopes of depressions compared with soil profiles in the depressions. High CO2 contents occur at depths from -40 to -80 cm and high and dense grassland shows high CO2 contents in the soil atmosphere. Grass roots may grow and are distribu     

碳酸锶-碳酸钠系熔盐相图研究

在碱金属碳酸盐熔盐中加入碳酸锶是抑制熔盐燃料电池中氧化镍阴极腐蚀的手段之一。研究含碳酸锶的碳酸盐熔盐系相平衡对碳酸盐熔盐燃料电池的电解质配方有参考价值。报道了用差热分析和目测法测量的Na2 CO3-SrCO3系熔盐相图的结果。结果表明碳酸锶在碳酸钠中存在有限固溶度 ,所形成的中间化合物Na2 Sr(CO3) 2 在 75 8℃异分熔化     

西安南郊春季土壤碳释放研究

本文根据NaOH溶液吸收CO2的原理，对西安长延堡春季土壤CO2释放量进行了观测，对土壤CO2释放规律及其影响因素进行了探讨。资料表明，从春季的3月到5月，不同植被下土壤CO2释放量均呈增加的趋势；植被对土壤CO2释放量有一定影响，植被发育好，土壤CO2释放量大；从当日早晨到次日早晨，土壤CO2释放量呈现由低到高再到低的变化规律；土壤CO2释放量变化相对于气温的变化具有滞后性，表明土壤CO2释放量变化是受土壤温度制约的。     

Magma traps: Part I,theory

The role of the buoyancy barrier of the stratified crust in controlling the ascent of magmas is represented by a model which operates close to lithostatic equilibrium and in which fractional crystallization of the magma or partial melting of the ambient rock can occur. The density structure of the crust has a powerful effect in trapping magma and thereby in controlling the occurrence of high level geothermal systems. The model is tested in Part II (this volume).