Land tenure and agricultural expansion in Latin America: The role of Indigenous Peoples’ and local communities’ forest rights

Agricultural expansion remains the most important proximate cause of tropical deforestation, while interactions between socio-economic, technological and institutional factors represent the fundamental drivers. Projected population increases could further raise the pressure on the remaining forests, unless agricultural intensification allows raising agricultural output without expanding agricultural areas. The purpose of this article is to understand the role of institutional factors in governing the intensification process towards the goal of preserving forests from agricultural pressures, with a focus on Indigenous Peoples’ and local communities’ rights to forests (as embedded in the various tenure regimes). In this paper we adopt an international dimension and analyse the process of agricultural expansion across eleven Latin American countries over the period 1990–2010 to assess whether, in a context of agricultural intensification, different land tenure regimes impact differently on the realization of land-sparing or Jevons paradox. The results, based on a number of multivariate statistical models that controls for socio-economic factors, strongly suggest that the formal recognition of Indigenous Peoples and local communities’ forest rights has played an important role in promoting land sparing or attenuating Jevons paradox.     

GWK-201型测氦仪标定方法探讨

介绍了GWK-201型测氦仪的一种标定方法,该方法是采用SP-2304A型气相色谱仪的测值与其对比的办法来判定仪器的稳定性.然后介绍了一组标定实例,对有关问题进行了讨论.综合分析认为;该方法可信度高,操作简单,值得推广.     

Calculation of the parameters of georesistivi－ty anisotropy and case history of earthquake precursors

Ｃａｌｃｕｌａｔｉｏｎｏｆｔｈｅｐａｒａｍｅｔｅｒｓｏｆｇｅｏｒｅｓｉｓｔｉｖｉ┐ｔｙａｎｉｓｏｔｒｏｐｙａｎｄｃａｓｅｈｉｓｔｏｒｙｏｆｅａｒｔｈｑｕａｋｅｐｒｅｃｕｒｓｏｒｓＦＵ－ＹＥＱＩＡＮ１）（钱复业），ＹＵ－ＬＩＮＺＨＡＯ１）（赵玉林）ａ...     

球面栅格空间中的Jordan曲线性质及其拓扑矛盾分析

定义了球面栅格空间的拓扑元素，给出球面栅格空间中邻近、连通和空间目标的内部、边界和外部等空间目标的拓扑定义及形式化描述，讨论了Jordan曲线在球面栅格空间中的性质及由此引起的拓扑矛盾。     

江苏溪桥地区氦气藏天然气富集规律及资源前景

江苏溪桥地区浅层盐城组氦气藏是典型的构造类型气藏，天然气富集受低幅构造控制。研究表明该地区氦气天然气资源存在较大的开发和利用前景。     

中国大陆含油气盆地的氦同位素组成及大地热流密度

根据天然气中氦同位素组成,讨论了中国大陆主要含油气盆地氦同位素地球化学特征与大地热流密度。不同地区425个~3He/~4He 值表明中国含油气盆地天然气的氦同位素组成变化范围较大,为4.0×10~(-9)-7.21×10~(-6),在统计直方图上呈现三个峰值:1.5×10~(-8),3.0×10~(-7)和1.5×10~(-6)。中国东部大陆裂谷系中、新生代盆地内天然气的~3He/~4He 值分布范围为1.02×10~(-7)-7.21×10~(-6),50%以上大于大气的值(1.4×10~(-6));其他地区含油气盆地天然气的~3He/~4He 值分布范围为4.0×10~(-9)-7.01×10~(-7),全部小于大气的~3He/~4He 值。根据天然气中~3He/~4He 值计算的大地热流密度值分布在30-82mW/m~2 之间。利用~3He/~4He 值计算的大地热流密度值与用其他方法测得的值相一致,在中国大陆水平方向上呈现"东高西低"的变化趋势。     

High resolution radio recombination line observations

Summary Over the last decade sensitive observations of radio recombination line emission using high angular resolution synthesis telescopes have become available. As a result it has now become possible to image the physical parameters deduced from radio recombination lines across individual sources. In the case of HII regions this work has resulted in detailed images of radial velocities, electron temperatures and the abundance of singly ionized helium (Y⁺). Direct observational evidence has been found for pressure broadening and non-LTE effects. Dramatic variations have been found in the ratio of He⁺ to H⁺, from as low as a few percent (the galactic centre) to as high 34% in one region of W3. Detailed images have been obtained of the partially ionized medium (CII and H regions) close to HII regions. Observations of recombination lines at very low frequencies have revealed the existence of very low density ionized gas in all directions in our galaxy. Higher resolution observations have led to a partial understanding of this medium. The first complete velocity field of the ionized gas in the centre of our galaxy has been obtained. Very recently the first images were made of extragalactic radio recombination lines, offering the possibility to study the kinematics of the ionized gas in the central few hundred parsecs of external galaxies.     

In situ cosmogenic Be in olivines and pyroxenes

This study proposes an efficient new cleaning procedure for measuring in situ cosmogenic ¹⁰Be in olivines and pyroxenes. This chemical routine is specially designed to decontaminate the abundant meteoric ¹⁰Be from these minerals. The method was tested on mafic minerals from basaltic flows of Mt. Etna volcano and from Hawaiian flows and moraines. A sequential dissolution test shows that ¹⁰Be concentrations decrease with the number of cleaning steps until reaching a constant value. This is a necessary condition to demonstrate the efficiency of the method in properly decontaminating samples of meteoric ¹⁰Be. Moreover, cross-calibration with cosmogenic ³He measured within the same samples yielded a sea level high-latitude production rate of 4.5±0.4 at g⁻¹ a⁻¹ for cosmogenic ¹⁰Be in mafic minerals. This rate is within 1σ uncertainty of empirically or model-derived rates for ¹⁰Be on the same targets. Such concordance supports the consistency of the new method.     

The crater lake and hydrothermal system of Mount Pinatubo,Philippines: evolution in the decade after eruption

The June 1991 eruption of Mount Pinatubo, Philippines breached a significant, pre-eruptive magmatic-hydrothermal system consisting of a hot (>300 °C) core at two-phase conditions and surrounding, cooler (<260 °C) liquid outflows to the N and S. The eruption created a large, closed crater that accumulated hydrothermal upwellings, near-surface aquifer and meteoric inflows. A shallow lake formed by early September 1991, and showed a long-term increase in level of ~1 m/month until an artificial drainage was created in September 2001. Comparison of the temporal trends in lake chemistry to pre- and post-eruptive springs distinguishes processes important in lake evolution. The lake was initially near-neutral pH and dominated by meteoric influx and Cl–SO₄ and Cl–HCO₃ hydrothermal waters, with peaks in SO₄ and Ca concentrations resulting from leaching of anhydrite and aerosol-laden tephra. Magmatic discharge, acidity (pH~2) and rock dissolution peaked in late 1992, during and immediately after eruption of a lava dome on the crater floor. Since cessation of dome growth, trends in lake pH (increase from 3 to 5.5), temperature (decline from 40 to 26 °C), and chemical and isotopic composition indicate that magmatic degassing and rock dissolution have declined significantly relative to the input of meteoric water and immature hydrothermal brine. Higher concentrations of Cl, Na, K, Li and B, and lower concentrations of Mg, Ca, Fe, SO₄ and F up to 1999 highlight the importance of a dilute hydrothermal contribution, as do stable-isotope and tritium compositions of the various fluids. However, samples taken since that time indicate further dilution and steeper trends of increasing pH and declining temperature. Present gas and brine compositions from crater fumaroles and hot springs indicate boiling of an immature Cl–SO₄ geothermal fluid of near-neutral pH at approximately 200 °C, rather than direct discharge from magma. It appears that remnants of the pre-eruptive hydrothermal system invaded the magma conduit shortly after the end of dome emplacement, blocking the direct degassing path. This, along with the large catchment area (~5 km²) and the high precipitation rate of the area, led to a rapid transition from a small and hot acid lake to a large lake with near-ambient temperature and pH. This behavior contrasts with that of peak-activity lakes that have more sustained volcanic gas influx (e.g., Kawah Ijen, Indonesia; Poas and Rincón de la Vieja, Costa Rica).Editorial responsibility: H. Shinohara     

Activation energy for diffusion of helium in water-saturated, compacted Na-montmorillonite

It is important to clarify the migration behavior of hydrogen gas dissolved in water-saturated, compacted bentonite, which is a promising material for geologic disposal of high-level waste and TRU waste disposal. The diffusion coefficients of helium, which can be detected under extremely low background conditions, in water-saturated, compacted Na-montmorillonite were determined as a function of temperature by a transient diffusion method. The activation energies for diffusion of helium were then obtained. The activation energies were from 6.9 ± 4.8 to 19 ± 2.8 kJ mol^− 1 and were regarded to be independent of dry density. The activation energies of helium in water-saturated Na-montmorillonite were roughly equal to those in bulk water, 14.9 kJ mol^− 1, and in ice, from 11 to 13 kJ mol^− 1. It is possible that helium diffuses not only in pore water but also in interlayer water.