ENVIRONMENTAL SUSTAINABILITY AND SCENARIOS OF URBANIZATION IN ARID AREA——A Case Study in Wuwei City of Gansu Province

1IN T R O D U C T IO N The western China isfacinggrowing problems of eco- logicaland economic development. The disparitiebse- tween the socio-economy of the western and eastern China were enlarging, and the major ecologicalprob- lems stilelvolve as past(H…     

Seasonal and annual variation of CO2 flux above a broad-leaved Korean pine mixed forest

Long-term measurement of carbon metabolism of old-growth forests is critical to predict their behaviors and to reduce the uncertainties of carbon accounting under changing climate. Eddy covariance technology was applied to investigate the long-term carbon exchange over a 200 year-old Chinese broad-leaved Korean pine mixed forest in the Changbai Mountains (128°28′E and 42°24′N, Jilin Province, P. R. China) since August 2002. On the data obtained with open-path eddy covariance system and CO₂ profile measurement system from Jan. 2003 to Dec. 2004, this paper reports (i) annual and seasonal variation of F _NEE, F _GPP and R _E; (ii) regulation of environmental factors on phase and amplitude of ecosystem CO₂ uptake and release Corrections due to storage and friction velocity were applied to the eddy carbon flux.

L_AI and soil temperature determined the seasonal and annual dynamics of F_GPP and R_E separately. V_PD and air temperature regulated ecosystem photosynthesis at finer scales in growing seasons. Water condition at the root zone exerted a significant influence on ecosystem maintenance carbon metabolism of this forest in winter.

The forest was a net sink of atmospheric CO₂ and sequestered −449 g C·m⁻² during the study period; −278 and −171 gC·m⁻² for 2003 and 2004 respectively. F _GPP and F _RE over 2003 and 2004 were −1332, −1294 g C·m⁻². and 1054, 1124 g C·m⁻² respectively. This study shows that old-growth forest can be a strong net carbon sink of atmospheric CO₂.

There was significant seasonal and annual variation in carbon metabolism. In winter, there was weak photosynthesis while the ecosystem emitted CO₂. Carbon exchanges were active in spring and fall but contributed little to carbon sequestration on an annual scale. The summer is the most significant season as far as ecosystem carbon balance is concerned. The 90 days of summer contributed 66.9, 68.9% of F _GPP, and 60.4, 62.1% of R _E of the entire year.

     

Major features of warm and cold eddies south of the Nansei Islands

As regards the eddies occurring in the origination region of the Kuroshio (west of 130° E), the earliest informations were reported by R. Shigematsu (1932) and K. Koenuma (1936) respectively. From the data observed in the twenties, they pointed out that there was a warm eddy located to the right side of the Kuroshio in the Luzon Strait. Using the data obtained from the fourties through the sixties, Nitani further convinced the existence of the warm eddy. During the latest two decades, observations of the area south of the Nansei Islands on board of R/V Chofu Maru (1965, '66, '67) and Hakuho Maru (1974, '75) also revealed the existence of warm and cold eddies, but few works on "eddies" are reported, so far as we know.     

Decoupling of stalagmite-derived Asian summer monsoon records from North Atlantic temperature change during marine oxygen isotope stage 5d

The Asian monsoon is an important component of the global climate system. Seasonal variations in wind, rainfall, and temperature associated with the Asian monsoon systems affect a vast expanse of tropical and subtropical Asia. Speleothem-derived summer monsoon variation in East Asia was previously found to be closely associated with millennial-scale change in temperature in the North Atlantic region between 75 and 10 ka. New evidence recovered from East Asia, however, suggests that the teleconnection between summer monsoon in East Asia and temperature change in the North Atlantic region may have significantly reduced during 120 to ~ 110 ka, a period directly after the full last interglaciation and corresponding roughly to marine oxygen isotope stage 5d. This reduction may be due to the low ice volume in the North Hemisphere at that time, which makes the millennial-scale change in temperature in the North Atlantic region less effective in influencing the Asian summer monsoon. This is important for investigating the mechanisms controlling the Asian summer monsoon and the paleoclimatic teleconnection between East Asia and the North Atlantic region, and for predicting monsoon-associated precipitation in East Asia under a global-warming trend.     

内蒙古敖包吐萤石矿床的Sr、Nd、Pb同位素地球化学特征

敖包吐萤石矿床是内蒙古北部苏莫查干地区单一萤石矿集区中的一个代表性矿床,产于早二叠世大石寨组火山-沉积岩与早白垩世敖包吐花岗岩的接触带上。文章通过分析该矿床岩、矿石的微量元素和稀土元素,揭示出萤石的成矿作用可分为2个阶段,即交代作用和充填作用。交代作用过程中大石寨组的结晶灰岩可能为萤石的形成提供了部分Ca来源,萤石矿石的稀土元素配分模式与海水基本类似,具有Ce负异常;成矿作用后期主要表现为充填作用,形成颗粒粗大的萤石,表现为重稀土元素富集的特征,并随着萤石的沉淀析出,稀土元素总量逐渐下降,反映出成矿流体经历了较长期的演化过程。各地层单元、花岗岩体和萤石矿石的Sr、Nd、Pb同位素研究表明,萤石的放射性同位素组成具有壳、幔源混合的特点,成矿物质来源具有多源性。早白垩世敖包吐花岗岩可能是萤石中F的主要来源,而大石寨组的结晶灰岩则可能提供了Ca。另外,Pb、Nd同位素的极大不均一性,有可能是成矿流体在运移过程中对艾力格庙群放射性组分的选择性吸收的结果。萤石成矿作用与钾玄岩的时空关系暗示了萤石的成矿过程可能是中国东部岩石圈减薄和下地壳的置换地质事件的结果。在构造转型的过程中,燕山中期富碱的酸性花岗岩浆的活动分异出富含F的成矿流体,与幔源流体混合,沿区域重新活化的深大断裂和大石寨组的层间破碎带上升,交代其间的灰岩透镜体,从而形成敖包吐中型萤石矿床。     

相山铀矿田成矿物质来源探讨

铀源分析是铀矿床成因研究中的关键问题.在分析区域铀丰度特征的基础上,根据区域成矿物质在地质历史过程中的时空演化,结合相山矿田矿石铅同位素组成及岩、矿石微量元素地球化学对矿田铀源分析的指示,认为下寒武统地层为区域铀源层,相山火山盆地是区域成矿物质的"汇"区,岩浆及期后热液是铀的载体,即岩浆作用实现了铀从"源"到"汇"之间的物质转移.在岩浆演化过程中,铀向气液转移,为铀成矿提供了物质基础,岩浆期后流体-岩石相互作用,也促使了基底片岩、流纹英安岩中的部分铀进入成矿溶液.     

分光光度法测定海洋河弧菌510脂多糖

本文研究了直接测定海洋河弧菌 (vibrio fluvailis) 5 10脂多糖的分光光度法。利用 1,9-二甲基亚甲蓝 (DMB) ,在适当条件下同脂多糖发生染色反应 ,在 5 5 0 nm波长下 ,反应体系的吸光值同脂多糖含量呈线性相关。相关系数为 0 .9993,最低检出限为 10 μg/m L,相对标准偏差为 1.6 2 ,平均回收率为 (10 5± 2 .18) %。     

均匀层浅海声场与海底反射损失的关系

海底对浅海声传播的影响很大。海底有复杂的多层结构。在计算声场时如果把多层海底的影响都考虑进去,就会使计算复杂化,得不出一个清晰的物理图象。因此,在计算中往往使用海底反射损失系数来代替多层海底的模型。但海底反射损失与角度有复杂的依赖关系。为了计算方便,提出过不少简化模型。已经使用的模型有反射损失与角度无关、与角度一次方成正比;后来又提出反射损失在某一临界角之下与角度一次方成正比,在临界角之上与角度无关的三参数模型,克服了远场与近场衔接的问题[1,2]。但这些模型不一定在所有情况下都能反映海底反射损失与角度的关系的主要特征。本文提出一个近似方法,可以计算海底反射损失按任意规律随角度单调上升的情况下的声场。     

海带育苗水系微生物的监测与控制

现场及实验室试验表明,近岸水中细菌丰度因时因地有较大差别,近岸水在潮周期中以高潮前后细菌量较低;海水在沉淀贮存过程中细菌丰度有明显变化,且与海水中营养物含量、贮存温度等有关;海水经沙滤后能减少细菌90％左右;回水中脱落苗进入贮水池,是贮水池中细菌数量增长10余倍的主要原因。     

Relationship between biogeochemical features of biogenic elements and flocculation in the Changjiang Estuary

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