Characterizing evapotranspiration over a meadow ecosystem on the Qinghai-Tibetan Plateau

To characterize evapotranspiration (ET) over grasslands on the Qinghai-Tibetan Plateau, we examined ET and its relevant environmental variables in a Kobresia meadow from 2002 to 2004 using the eddy covariance method. The annual precipitation changed greatly, with 554, 706, and 666 mm a(-1) for the three consecutive calendar years. The annual ET varied correspondingly to the annual precipitation with 341, 407, and 426 mm a(-1). The annual ET was, however, constant at about 60% of the annual precipitation. About 85% annual ET occurred during the growing season from May to September, and the averaged ET for this period was 1.90, 2.23, and 2.22 mm/d, respectively for the three consecutive years. The averaged ET was, however, very low (< 0.40 mm/d) during the nongrowing season from October to April. The annual canopy conductance (gc) and the Priestley-Taylor coefficient (a) showed the lowest values in the year with the lowest precipitation. This study first demonstrates that the alpine meadow ecosystem is characterized by a low ratio of annual ET to precipitation and that the interannual variation of ET is determined by annual precipitation.

Observation and modeling for terrestrial processes in alpine meadow

The water-heat transfer process between land and atmosphere in Haibei alpine meadow area has been systematically observed. A multi-layer coupling model for land-atmosphere interaction was presented with special attention paid to the moisture transfer in leaf stomata under unsaturated condition. A profound investigation on the physical process of turbulent transfer inside the vegetation has been performed with a revised formula of water absorption for root system. The present model facilitates the study of vertically distributed physical variables in detail. Numerical simulation was conducted according to the transfer process of Kinesia humility meadow in the area of Haibei Alpine Meadow Ecosystem Station, CAS. The calculated results agree well with observation.

超高压输电线路巡检机器人越障控制问题的研究

给出了一种超高压输电线路巡检机器人控制系统的设计与实现方法.根据机器人的作业任务,提出了基于传感器信息、约束信息以及动作反馈信息作为输入,产生式系统作为动作输出的越障控制方式.仿真结果表明此方法对于机器人的越障过程是有效的.

Zr^4＋和Hf^4＋在水合氧化铁上的吸附及其分异的实验研究

本文研究了4价阳离子Zr、Hf在水合氧化铁(HFO)上的吸附及其在胶体／溶液界面的分异行为。研究结果表明：等价元素Zr、Hf在HFO上的吸附是非线性的，在吸附和共沉淀过程中二者发生了分异，Zr的吸附能力要大于Hf；pH<6时，固相中Zr／Hf比值随pH的升高迅速降低，而在天然水体pH范围内(pH≥6)，Zr、Hf的吸附量Q及Zr／Hf比值则不随pH发生变化，显示了Zr、Hf在表生环境中的相对惰性行为。本研究为吸附／解吸或水／粒相互作用导致Zr、Hf在地表环境的分异提供了实验证据。

多形态自然硒的首次发现及其成因初探

在湖北省恩施市渔塘坝的富硒碳质硅质岩、碳质页岩及其废弃岩中堆中，作者首次发现了多种形态的自然硒。本文根据自然硒的产出环境和成因将其分为三种，一种产于近地表废弃“石煤”堆中；一种与构造作用有关；另一种与表生风化作用有关。近地表废弃“石煤”堆中的自然硒是与岩层（或自燃）有关，见有晶形完好、颗粒粗大的晶体；与构造作用有关的自然硒多为毛发状、针状；与表生风化作用有关的自然硒颗粒细小，针状晶体少见.

云南金宝山岩体岩浆起源的微量元素模式分析

金宝山镁铁一超镁铁岩体是峨眉山大火成岩省一个典型的岩浆Cu-Ni—PGE成矿岩体。在根据成岩机制概算原始岩浆微量元素含量的基础上，通过模式计算，表明原始岩浆强不相容元素相对富集型式不可能由现有原始地幔或亏损地幔模型的单一源区熔融或融体混合作用形成，原始岩浆起源于类似OIB源的地幔柱高程度熔融，熔融程度在2o％左右。

中旬红山矽卡岩铜矿稳定同位素特征及其对成矿过程的指示

红山铜矿床位于三江地区义敦岛弧南端的中甸弧，是在晚三叠世甘孜-理塘洋盆向西俯冲过程中形成的一个中型规模的矽卡岩矿床。通常，矽卡岩体就是铜矿体或铜矿化体，主要呈似层状、层状、脉状及透镜体状产于大理岩与角岩接触带或局部在角岩中，未见其与侵入岩直接接触。通过对不同成矿阶段所形成的石榴石、磁铁矿、磁黄铁矿、黄铁矿、黄铜矿、方解石等典型矿物以及大理岩的稳定同位素特征研究，发现矽卡岩的最主要组成矿物石榴石的δ^18OSMOW范围为6．2—8．3‰，反映了矽卡岩可能直接继承隐伏斑岩体的氧同位素组成。根据磁铁矿的氧同位素组成（5．5—7．1‰）所计算的磁铁矿化阶段成矿流体的δ^18OSMOW为13．1—14．7‰（400℃）或12．5—14．1％。（500℃），暗示有富集δ^18O的CO2溶入到成矿流体中。硫化物的δ^34SCDT范围4．45—6．20‰，说明矿床具有高度均一的硫源，并且在硫化物的结晶沉淀过程中，流体中硫同位素分馏很弱。由此推测主成矿期成矿流体的δ^34S∑S为5．6±0．6‰。矿床中的大理岩的δ^13CPDB为2．0—2．2‰，δ^18OSMOW为24．0—24．8‰，说明大理岩是由海相碳酸盐岩经重结晶作用而成。成矿晚期阶段形成的方解石脉的δ^13CPDB范围是-2．4—1．7‰，δ^18OSMOW范围是16．3—22．4‰，表明其C和O主要来源于大理岩。总之，我们推测红山矽卡岩很可能主要是由中酸性岩浆浅成侵位时局部同化碳酸盐围岩所形成的一种富含钙质成分的次生岩浆就位于碎屑岩与碳酸盐岩之间的构造薄弱带冷凝固结而成，矽卡岩型矿化与深部斑岩型矿化具有共同的成矿物质和成矿流体来源。

滇黔桂地区铊富集的矿化剂和沉淀富集剂及成矿模式

T1虽然是一种分散元素，但在一定条件下也是可以富集的，甚至形成独立矿体。笔者在分析滇黔桂地区富铊矿床的地球化学特征后，认为T1在低温阶段富信，并提出T1的富集与沉积盆地局部高地球化学背景有关；促使T1富集万丈和的主要条件是矿化剂和沉淀富集剂，卤素和有机质是主要的成矿化剂，富硫流体和热液改造的有机质是主要的沉淀富集剂，在此基础上进一步探讨铊的二期三阶段成矿模式。

近中性溶液条件下富镉铅锌矿矿石的风化淋滤实验研究

在近中性溶液条件下对富镉锌矿石进行了风化淋滤实验研究，发现淋滤液中产生大量以石膏为主要成分的沉淀物。淋滤液呈碱性，淋滤出来的Zn、Cd以水溶态和沉淀态形式存在，而以后者为主。淋滤50天后，黄铁矿闪锌矿石中Zn、Cd的淋滤率为0．03％和0．01％，而半氧化闪锌矿石Zn、Cd的淋滤率则高得多，分别0．10％和0．60％.

Photofragment translational spectroscopy of p-bromotoluene at 266 nm

Photodissociation of p-bromotoluene at 266 nm has been investigated on the universal crossed molecular beam machine, and translational energy distribution P(E-t) as well as the anisotropy parameter beta have been obtained. Photofragment translational energy distribution P(E-t) reveals that similar to 38.5% of the available energy is partitioned into translational energy. The anisotropy parameter beta is determined to be -0.4 +/- 0.2. From P(E-t) and beta, we deduce that p-bromotoluene photodissociation is a fast process and the perpendicular transition plays a central role at this wavelength. The possible mechanism has been discussed and comparison of p-bromotoluene with bromobenzene, o-bromotoluene has also been made. (C) 1999 Elsevier Science B.V. All rights reserved.