Fishers' perceptions,facilitating factors and challenges of community-based no-take zones in the Sian Ka’an Biosphere Reserve,Quintana Roo,Mexico

In response to fisheries decline in the Mexican Caribbean and continuing deterioration of the Mesoamerican Reef, conservation NGOs have begun to negotiate and collaboratively design a network of no-take zones (NTZs) with three fishing cooperatives in the Sian Ka’an Biosphere Reserve (SKBR), among other places along the coast of Quintana Roo. Spiny lobster (Panulirus argus) is the target of the main fishery within cooperative concessions. Fishers are uniquely positioned to enforce and monitor NTZs and evaluate their effectiveness. This study analyzes fishers' perceptions as indicators of social acceptance of NTZs, and identifies facilitating factors and challenges of the community-based process. Consistent with similar studies, responses of fishers (89 out of a population of 124) to a semi-structured interview showed that perceptions of NTZs largely reflect fishers' concerns and interests. A high proportion of fishers accurately identified main NTZ objectives of regulation, conservation and economic improvement, as well as NTZ locations. Further, fishers cared about ecosystem sustainability and, because NTZs would not significantly limit their main economic activity, endorsed the initiative while expecting additional benefits. Declining trends in lobster catch influenced a perceived need for NTZs. Major concerns were that illegal fishers would reap NTZ benefits and that economic impacts and benefits were uncertain. Most fishers found the decision-making process inclusive, were willing to take responsibility for enforcing NTZs and believed people leading the process were trustworthy. Differences in endorsement of NTZs among cooperatives points to the importance of understanding fishers’ incentives to collaborate, and the leadership and organizational dynamics which shape participatory processes. This analysis highlights challenges in advancing NTZs in complex ecological, socio-economic and regulatory contexts. It underscores the need for community-based processes that transcend understanding of conservation measures but also invests in sustainable, operative and trustful working relationships, as well as the urgency of interdisciplinary approaches in ensuring effective design and implementation of this relatively new fishery management tool.     

Geochemistry and Ar–Ar muscovite ages of the Daraban Leucogranite,Mawat Ophiolite,northeastern Iraq: Implications for Arabia–Eurasia continental collision

Daraban Leucogranite dykes intruded discordantly into the basal serpentinized harzburgite of the Mawat Ophiolite, Kurdistan region, NE Iraq. These coarse grained muscovite-tourmaline leucogranites are the first leucogranite dykes identified within the Mawat Ophiolite. They are mainly composed of quartz, K-feldspar, plagioclase, tourmaline, muscovite, and secondary phologopite, while zircon, xenotime, corundum, mangano-ilemnite and cassiterite occur as accessories.The A/CNK value of the granite dyke samples varies from 1.10 to 1.22 indicating a strongly peraluminous composition. CaO/Na₂O ranges from 0.11 to 0.15 and Al₂O₃/TiO₂ from 264 to 463, similar to the strongly peraluminous (SP) granites exposed in ‘high-pressure’ collision zones such as the Himalayas.Ar–Ar muscovite step-heating dating yields 37.57 ± 0.25 and 38.02 ± 0.53 Ma plateau ages for two samples which are thought to reflect either their magmatic emplacement or resetting during collision-related metamorphism. Mineral chemistry shows evidence of both primary and secondary types of muscovite, with cores favouring the magmatic interpretation and slight effects of a late syn-serpentinization fluid seen at the rims.Geochemical features of Daraban Leucogranite dykes favour a syn-collisional tectonic setting. They probably formed in response to the continental collision between Eurasia and Arabia during the initial stage of the opening of the Gulf of Aden at 37 Ma. The muscovite ages and geochemical features of Daraban Leucogranite are strong evidence for the timing of the continental collision between northeastern Arabia and Eurasia in Kurdistan region of Iraq.     

Sulfur Concentration in Geochemical Reference Materials by Solution Inductively Coupled Plasma‐Mass Spectrometry

With implications for the origin of ore deposits, redox state of the atmosphere, and effects of volcanic outgassing, understanding the sulfur cycle is vital to our investigation of Earth processes. However, the paucity of sulfur concentration measurements in silicate rocks and the lack of well‐calibrated reference materials with concentrations relevant to the rocks of interest have hindered such investigations. To aid in this endeavour, this study details a new method to determine sulfur concentration via high mass resolution solution inductively coupled plasma‐mass spectrometry (ICP‐MS). The method is based on an aqua regia leach, involving relatively rapid sample preparation and analysis, and uses small test portion masses (< 50 mg). We utilised two independently prepared standard solutions to calibrate the analyses, resulting in 4% accuracy, and applied the method to eight geochemical reference materials. Measurements were reproducible to within ~ 10%. Sulfur concentrations and isotopes of six reference materials were measured additionally by elemental analyser‐combustion‐isotope ratio mass spectrometry to independently evaluate the accuracy of the ICP‐MS method. Reference materials that yielded reproducible measurements identical to published values from other laboratories (JGb‐1, JGb‐2 and MAG‐1) are considered useful materials for the measurement of sulfur. Reference materials that varied between studies but were reproducible for a given test portion perhaps suffer from sample heterogeneity and are not recommended as sulfur reference materials.     

Properties of iron alloys under the Earth's core conditions

The Earth's core is constituted of iron and nickel alloyed with lighter elements. In view of their affinity with the metallic phase, their relative high abundance in the solar system and their moderate volatility, a list of potential light elements have been established, including sulfur, silicon and oxygen. We will review the effects of these elements on different aspects of Fe–X high pressure phase diagrams under Earth's core conditions, such as melting temperature depression, solid–liquid partitioning during crystallization, and crystalline structure of the solid phases. Once extrapolated to the inner–outer core boundary, these petrological properties can be used to constrain the Earth's core properties.     

彬长矿区煤层气储层参数及开发潜力

彬长矿区煤的变质程度低,矿井瓦斯涌出量大,瓦斯治理形势日趋严峻。根据矿区地质勘查、井下及煤层气井所获得的地质资料显示,煤层气开发的主要目标4煤层厚度大,分布稳定,煤体结构好,渗透率和气含量相对较高,气含量最高可达6.29m3/t,估算煤层气资源量为132.743×108m3。依据煤层气资源丰度划分,矿区煤层气富集区总面积为87.41km2,资源量为40.06×108m3,主要分布在大佛寺井田,相对富集区主要位于胡家河井田中南部和孟村井田东部,贫气区主要位于孟村井田西部、文家坡井田。综合分析认为研究区煤层气开发地质条件相对较好,属于可以抽采煤层,大佛寺井田为地面煤层气勘探开发最具潜力的地区。     

南岭西段加里东期苗儿山岩体锆石SHRIMPU-Pb年龄、地球化学特征及其构造意义

苗儿山岩体位于南岭西段,主体为加里东期花岗岩,少量印支期和早燕山期花岗岩。加里东期花岗岩具块状构造,由早期黑云母花岗闪长岩、中期斑状黑云母二长花岗岩和晚期细粒黑(二)云母二长花岗岩组成,以斑状黑云母二长花岗岩为主。对中期斑状黑云母二长花岗岩和晚期细粒二云母二长花岗岩各进行了1个样品的锆石SHRIMP U-Pb年龄测试,分别得到428.5±3.8 Ma、409±4 Ma的年龄值,反映出早志留世末、志留纪末-泥盆纪初2期岩浆事件。中期主体花岗岩具有富硅(SiO2=70.09%~76.59%)、中铝(Al2O3=12.71%~14.72%)、高钾(K2O=4.48%~5.73%)、中碱(Na2O+K2O=7.24%~7.91%)、高ASI(平均1.15)的特点,总体属高钾钙碱性系列过铝质花岗岩类。主体花岗岩微量元素中Ba、Nb、Sr、P、Ti表现为明显亏损,Rb、(Th+U+K)、(La+Ce)、Nd、(Zr+Hf+Sm)、(Y+Yb+Lu)等则相对富集,稀土总量中等(179.8×10-6~270.6×10-6),轻稀土富集[(La/Yb)N=5.07~14.33],具明显的负Eu异常(δEu=0.15~0.46)。岩体具有较高的ISr值(0.70660~0.72082)和较低的εNd(t)值(-8.29~-7.94),两阶段Nd模式年龄(t2DM)为1.81~1.84 Ga。C/MF-A/MF图解显示源岩为变质泥质岩和碎屑岩。上述地球化学特征表明花岗岩为S型花岗岩,源岩主要为中、上地壳岩石。花岗岩氧化物和微量元素构造环境判别图解指示岩体形成于后碰撞构造环境。基于岩石成因、构造环境判别以及区域构造演化过程,推断加里东期苗儿山花岗岩的具体形成机制为:在陆内强挤压之后挤压应力相对松弛、压力降低的后碰撞构造环境下,因地壳增厚而升温的中、上地壳岩石减压熔融并向上侵位。结合区域资料分析,苗儿山地区在奥陶纪末-志留纪初北流运动和志留纪后期的广西运动中均产生过强烈的陆内挤压和地壳增厚。     

Efficient block preconditioners for the coupled equations of pressure and deformation in highly discontinuous media

Large‐scale simulations of flow in deformable porous media require efficient iterative methods for solving the involved systems of linear algebraic equations. Construction of efficient iterative methods is particularly challenging in problems with large jumps in material properties, which is often the case in geological applications, such as basin evolution at regional scales. The success of iterative methods for this type of problems depends strongly on finding effective preconditioners. This paper investigates how the block‐structured matrix system arising from single‐phase flow in elastic porous media should be preconditioned, in particular for highly discontinuous permeability and significant jumps in elastic properties. The most promising preconditioner combines algebraic multigrid with a Schur complement‐based exact block decomposition. The paper compares numerous block preconditioners with the aim of providing guidelines on how to formulate efficient preconditioners. Copyright © 2010 John Wiley & Sons, Ltd.     

Spatio‐temporal distribution of near‐surface and root zone soil moisture at the catchment scale

Soil moisture is highly variable both spatially and temporally. It is widely recognized that improving the knowledge and understanding of soil moisture and the processes underpinning its spatial and temporal distribution is critical. This paper addresses the relationship between near‐surface and root zone soil moisture, the way in which they vary spatially and temporally, and the effect of sampling design for determining catchment scale soil moisture dynamics. In this study, catchment scale near‐surface (0–50 mm) and root zone (0–300 mm) soil moisture were monitored over a four‐week period. Measurements of near‐surface soil moisture were recorded at various resolutions, and near‐surface and root zone soil moisture data were also monitored continuously within a network of recording sensors. Catchment average near‐surface soil moisture derived from detailed spatial measurements and continuous observations at fixed points were found to be significantly correlated (r² = 0·96; P = 0·0063; n = 4). Root zone soil moisture was also found to be highly correlated with catchment average near‐surface, continuously monitored (r² = 0·81; P < 0·0001; n = 26) and with detailed spatial measurements of near‐surface soil moisture (r² = 0·84). The weaker relationship observed between near‐surface and root zone soil moisture is considered to be caused by the different responses to rainfall and the different factors controlling soil moisture for the soil depths of 0–50 mm and 0–300 mm. Aspect is considered to be the main factor influencing the spatial and temporal distribution of near‐surface soil moisture, while topography and soil type are considered important for root zone soil moisture. The ability of a limited number of monitoring stations to provide accurate estimates of catchment scale average soil moisture for both near‐surface and root zone is thus demonstrated, as opposed to high resolution spatial measurements. Similarly, the use of near‐surface soil moisture measurements to obtain a reliable estimate of deeper soil moisture levels at the small catchment scale was demonstrated. Copyright © 2007 John Wiley & Sons, Ltd.     

Effective block diagonal preconditioners for Biot's consolidation equations in piled‐raft foundations

The finite element (FE) simulation of large‐scale soil–structure interaction problems (e.g. piled‐raft, tunnelling, and excavation) typically involves structural and geomaterials with significant differences in stiffness and permeability. The symmetric quasi‐minimal residual solver coupled with recently developed generalized Jacobi, modified symmetric successive over‐relaxation (MSSOR), or standard incomplete LU factorization (ILU) preconditioners can be ineffective for this class of problems. Inexact block diagonal preconditioners that are inexpensive approximations of the theoretical form are systematically evaluated for mitigating the coupled adverse effects because of such heterogeneous material properties (stiffness and permeability) and because of the percentage of the structural component in the system in piled‐raft foundations. Such mitigation led the proposed preconditioners to offer a significant saving in runtime (up to more than 10 times faster) in comparison with generalized Jacobi, modified symmetric successive over‐relaxation, and ILU preconditioners in simulating piled‐raft foundations. Copyright © 2012 John Wiley & Sons, Ltd.     

Measuring the flow resistance of submerged grass

Through laboratory experiments conducted in a grass‐lined flume, the hydraulic resistance of grass is measured and quantified. For the grass examined, it is found that Manning's n value is greater than those recommended in well‐established texts such as Chow (1959. Open Channel Flow. McGraw‐Hill: Singapore), relatively lower than those predicted by n‐UR methods, but corresponds well with the value found from calibration studies of two‐ and three‐dimensional numerical models. The assumption of a uniform Manning's n value with flow depth, which is often made in numerical modelling, may be invalid depending on the relative submergence of the vegetation. Drag coefficients are evaluated for a method applicable to three‐dimensional numerical models. Further detailed experimental investigation and application of these approaches within a numerical modelling framework is now recommended. Copyright © 2002 John Wiley & Sons, Ltd.