Hunting Increases Dispersal Limitation in the Tree Carapa procera, a Nontimber Forest Product

Abstract:  The sustainability of seed extraction from natural populations has been questioned recently. Increased recruitment failure under intense seed harvesting suggests that seed extraction intensifies source limitation. Nevertheless, areas where more seeds are collected tend to also have more intense hunting of seed-dispersing animals. We studied whether such hunting, by limiting disperser activity, could cause quantitative dispersal limitation, especially for large crops and for crops in years of high seed abundance. In each of four Carapa procera (Meliaceae) populations in French Guiana and Surinam, two with hunting and two without, we compared seed fate for individual trees varying in crop size in years of high and low population-level seed abundance. Carapa seeds are a nontimber forest product and depend on dispersal by scatter-hoarding rodents for survival and seedling establishment. Hunting negatively affected the proportion of seeds dispersed and caused greater numbers of seeds to germinate or be infested by moths below parent trees, where they would likely die. Hunting of seed-dispersing animals disproportionally affected large seed crops, but we found no additional effect of population-level seed abundance on dispersal rates. Consistently lower rates of seed dispersal, especially for large seed crops, may translate to lower levels of seedling recruitment under hunting. Our results therefore suggest that the subsistence hunting that usually accompanies seed collection is at the cost of seed dispersal and may contribute to recruitment failure of these nontimber forest products. Seed extraction from natural populations may affect seedling recruitment less if accompanied by measures adequately incorporating and protecting seed dispersers.     

联合改良剂对桉树吸收重金属的作用——以矿区土壤中Cd、Zn和Cu为例

通过5种矿区土壤的盆栽试验,研究了联合改良剂对桉树部分生理指标、根中Cd、Zn和Cu的含量、以及土壤中Cd、Zn和Cu的BCR提取形态的影响,探讨了其对矿区土壤还林的作用.结果表明,与对照相比,施用改良剂后桉树的生物量和叶绿素含量的增幅分别为-7.6%~158.8%和-0.7%~23.1%,丙二醛含量的降幅为2.6%~37.9%,其中部分处理的生物量和丙二醛含量的变化达到显著水平（P<0.05）;土壤中有效态Cd、Zn和Cu的含量分别下降12.5%~63.8%、1.6%~54.7%和16.2%~57.6%,桉树根中Cd、Zn和Cu的含量分别下降3.1%~56.6%、-1.5%~21.3%和9.3%~50.1%.土壤对桉树根中Cd、Zn和Cu的含量有显著影响（P<0.05）,改良剂的配比或施用量无显著影响（P>0.05）,但在5种矿区土壤中G3降低桉树根中Cu含量的效果优于G1和G2;在重金属含量最高的2种土壤中,G1降低桉树根中Cd和Zn含量的效果优于G2和G3.研究表明施用联合改良剂能降低桉树对重金属的吸收,有利于矿区土壤的还林.     

约束条件下中国循环经济发展中的生态效率——基于优化的超效率SBM-Malmquist-Tobit模型

以中国30个省份、直辖市、自治区的年度面板数据为研究对象,重点将生态资源存量和环境污染造成的经济浪费两项指标纳入新的生态效率评价体系,运用优化的引入非期望产出的超效率SBM模型测算生态效率,再运用Malmquist指数考察全要素生产率（TFP）与生态效率的动态变动关系,最后运用Tobit回归分析探索生态效率主要影响因素的方向、强度和变化趋势,以此度量和展现循环经济发展的整体情况.结果显示：生态效率呈现由东到西、由沿海到内陆逐渐收敛的格局,东部沿海地区和中部、西部内陆地区间,循环经济发展水平存在显著的阶梯式区域失衡;生态效率的集群效应明显,辐射效应不足,不同地区或同一地区的不同省份间,循环经济发展水平同样参差不齐;经济发展引发的生态赤字问题逐步缓解,但在短时间内经济和生态的矛盾依旧存在,西北地区尤为突显;第三产业比重、技术进步、市场开放对生态效率的提升具有积极作用且趋于强化;政府规制、人口密度对生态效率的提升也具有积极作用但趋于减弱;第二产业比重、能源结构对生态效率的改善存在负面影响亦趋于强化.     

基于有限元分析的橡胶减振器优化设计

目的加快橡胶减振器的设计过程。方法分析橡胶材料及Mooney-Rivllin橡胶本构模型特点,介绍橡胶减振器应用特点及隔振设计的相关理论,采用Mooney-Rivllin模型模拟橡胶材料的力学特性,通过引进有限元优化技术,在设计初期保证减振器的刚度特性。结果在某设备减振设计中,采用单轴拉压曲线获取了橡胶材料的Mooney-Rivllin模型参数,以减振器的部分结构尺寸为设计参数,减振器的三向刚度为设计目标,获取了三轴向频率近似相等的隔振系统(轴向频率40 Hz、径向频率40.9 Hz)。通过试验测试,减振系统频率与试验值差别较小,其中轴向差别为2%,径向差别为1%。结论通过引进有限元优化技术,采用合理的橡胶本构模型,可以满足工程精度要求,加速了橡胶减振器的设计过程。     

铝合金的实验室盐雾试验腐蚀行为图像特征提取

目的提取铝合金材料在盐雾箱试验中可以表征腐蚀程度的表面形貌图像特征量。方法首先,对采集于表面化学清洗过的试样原始图像进行图像增强等预处理,突出腐蚀部位;其次,基于数字图像处理的分形和小波分解方法提取出分形维数和小波能量特征值。结果与以质量损失量为基础的腐蚀深度特征值进行相关性对比,基于图像分析的特征提取法的准确度和精度比较高。结论该方法可以应用于对试样的腐蚀程度进行定性和定量分析,判断并预测试样的腐蚀速度。     

Determination of organophosphorus pesticides and related compounds in water samples by membrane extraction and gas chromatography

A membrane extraction-gas chromatography method was developed fordetermination of organophosphorus pesticides and related compounds including methamidophos, DDVP, dimethoate, methyl parathion, parathion, thiophosphoric acid trimethyl ester, and thiophosphoramidic acid dimethyl ester in water samples. In thismethod, surface-modified acetic cellulose membranes were used to extract the target analytes in water samples, the extracted analytes were back-extracted into a small amount of methanol, andgas chromatography with pulsed flame photometric detector (GC-PFPD) was used to determine the concentrations of targetanalytes in the extracts. The recoveries obtained for thetarget analytes spiked into the water samples ranged from 66to 94%. The method detection limit for each target analyte was 0.05 g L^-1. The method developed in this study had shown the advantages of being cheap, simple, fast, and reliable. It had been used successfully to determine the concentrations of target analytes in river water samples.     

Fractionation of Cu, Pb and Zn in certified reference soils SRM 2710 and SRM 2711 using the optimized BCR sequential extraction procedure

Sequential extraction of metals from solid media is a common analytical tool used in environmental and exploration geochemistry. A number of procedures exist, but without harmonization and standardization, meaningful comparisons are tenuous without baseline data. A newly developed, standardized sequential extraction procedure (optimized BCR) was applied to two contaminated certified reference soils from Montana, US (SRM 2710 and SRM 2711) for Cu, Pb and Zn. Four operationally defined fractions were isolated, acid extractable, reducible, oxidizable, and residual (by aqua regia). Fraction-specific concentrations, percentages and recoveries for Cu, Pb and Zn were used to explore differences between the optimized BCR procedure and three other sequential extraction schemes with published data for SRM 2710 and 2711 (i.e. Tessier scheme, Geological Survey of Canada scheme and the original BCR scheme). Results indicate significant differences between the four schemes, even for schemes that are closely associated (i.e. the original and optimized BCR schemes). Order-of-magnitude fraction-specific concentration differences were observed, especially for Pb in the reducible fraction. Differences between schemes are worrisome because trends varied between metals, between fractions and between reference soils. These data reinforce the need for increased adoption of standardized sequential extraction procedures and further examination of different solid media.     

石油亚砜萃取巯基醋酸的研究

对石油亚砜(PSO)萃取巯基醋酸的条件和影响进行了实验研究,确定了石油亚砜通过氢键和巯基醋酸形成的萃合物的组成.为从废水中回收巯基醋酸以及石油硫醚的综合利用提供了依据.     

正己烷萃取—此外分光光度法测定矿井水中微量油

在进行矿井水中油类分析时，用正己烷作为萃取剂，以工作曲线代替标准曲线，从而使油平均回收率增加到96％以上。并在正己烷用量、水样预处理等测试参数选择上做了条件试验。     

Studies on the use of power ultrasound in solid–liquid myrobalan extraction process

Focus on eco-friendly processing techniques makes vegetable tanning a viable option in leather processing and establishes the subsequent need for the more efficient methods of extraction in tannin manufacture. Application of ultrasound has been tried in the extraction of tannins from myrobalan nuts in order to improve the extraction efficiency, to perform the extraction under milder process conditions and to reduce the process time. The influence of process parameters such as ultrasonic output power, time and temperature has been studied. Scale-up trials and the use of ultrasound in pulse mode have also been attempted. The results show that a three- to fivefold improvement is possible with ultrasonic output from 20 to 100 W. Extraction efficiency has been calculated from the maximum extractable materials from myrobalan nuts. Extraction efficiency is found to be 90% for ultrasound, 100 W without external heating as compared to 77% for control process at 70 °C for 4 h. Therefore, ultrasound could be employed even dispensing with provision for temperature controls. The use of ultrasound in pulse mode offered 70% extraction efficiency of continuous mode. Scale-up trials indicate that there exists an optimum ultrasonic output power depending on the amount of nuts used, to achieve better extraction efficiency. The effectiveness of ultrasonically extracted tannin solution has also been tested in the tanning process for its applicability. The degree of tanning efficacy has been assessed by shrinkage temperature measurement. The results indicate that ultrasonically extracted tannin solution is suitable for tanning process. Therefore, application of ultrasound in tannin extract manufacture is a viable option with added advantages.