老君山成矿区变质成因夕卡岩的地质地球化学特征

老君山成矿区广泛分布的夕卡岩是主要含矿岩层。通过对夕卡岩地质特征岩石化学特征、稀土结球化学特征和成岩年龄的分析研究,证明了夕卡岩是区域变质作用的产物。     

南沙群岛海区晚第四纪深海碳酸盐沉积作用

根据５个柱样分析，讨论了冰期一间冰期碳酸盐沉积作用变化，南沙海区碳酸盐旋回在３５００ｍ以浅表现为大西洋旋回，源于冰期陆源碎屑物质的稀释作用，相反，在３５００ｍ以下出现太平洋碳酸钙旋回，文中根据浮游有孔虫的溶解指数和种属数量讨论了冰期－间冰期溶解作用变化。     

栅栏在防止前沿积沙中的作用——以沙坡头地区为例

在沙坡头地区的铁路北侧,进行了防护带的前沿栅栏阻沙试验研究。经过三个风季初步观测表明:格状沙丘的主梁移动是缓慢的,通过栅栏阻沙量计算求得其移速为0.56米/年。而沙丘副梁的前移迅速是格状沙丘的主要运动及其危害形式。据测定主风向上的可能输沙量平均为6.5m³/米宽·年,栅栏阻沙量平均为5.5m³/米宽·年,栅栏平均阻沙效率为70-80%。因此,利用栅栏等工程措施防止防护带前沿积沙是可行的,有效的。     

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川、滇、黔接壤地区铅锌矿床产出的大地构造演化背景及成矿作用

川、滇、黔接壤地区铅锌矿床的分布受大地构造演化背景的控制。天宝山矿床与成矿有关的构造变形的应力、应变场的分析显示与区域变形相对应的区域性应力场有印支晚期和燕山期两期,其主压应力方向分别为NWW向和SSW向,印支晚期区域性近东西向的挤压是形成NWW向容矿的张性断裂的主要动力,该期为主构造期;燕山期NNE-SSW向的区域性挤压应力,具有引发区域性NEE向张性容矿构造的条件。结合区域岩浆活动和矿床同位素年龄资料的分析,认为印支晚期和燕山期发生的两次区域性小规模的岩浆活动与铅锌成矿有较密切的联系,岩浆活动可能为成矿提供了部分成矿物质和热能。构造应力、应变场所反映的构造期次、区域性的构造岩浆热事件与铅锌矿床的成矿在时间上是同步的。该地区铅锌矿两期主要的成矿作用分别和晚三叠世扬子板块与兰坪-思茅地块碰撞、义敦弧与扬子板块碰撞,以及早侏罗世西南部的雅鲁藏布江洋打开、扩张的时间一致。该地区两期主要的成矿作用发生在三叠纪晚期和早侏罗世。     

Controls of preferential orientation of earthquake- and rainfall-triggered landslides in Taiwan's orogenic mountain belt

Landsliding usually occurs on specific hillslope aspect, which may reflect the control of specific geo-environmental factors, triggering factors, or their interaction. To explore this notion, this study used island-wide landslide inventories of the Chi-Chi earthquake in 1999 (M_W = 7.6) and Typhoon Morakot in 2009 in Taiwan to investigate the preferential orientation of landslides and the controls of landslide triggers and geological settings. The results showed two patterns. The orientations of earthquake-triggered landslides were toward the aspect facing away from the epicenter in areas with peak ground acceleration (PGA) ≥ 0.6 g and landslide ratio ≥ 1%, suggesting that the orientations were controlled by seismic wave propagation. Rainfall-triggered landslides tended to occur on dip slopes, instead of the windward slopes, suggesting that geological settings were a more effective control of the mass wasting processes on hillslope scale than the rainfall condition. This study highlights the importance of the endogenic processes, namely seismic wave and geological settings, on the predesigned orientation of landslides triggered by either earthquake or rainfall, which can in turn improve our knowledge of landscape evolution and landslide prediction. © 2019 John Wiley & Sons, Ltd.     

Reductive dechlorination of polychlorinated biphenyls is coupled to nitrogen fixation by a legume-rhizobium symbiosis

Chlorinated persistent organic pollutants, including polychlorinated biphenyls(PCBs), represent a particularly serious environmental problem and human health risk worldwide. Leguminous plants and their symbiotic bacteria(rhizobia) are important components of the biogeochemical cycling of nitrogen in both agricultural and natural ecosystems. However, there have been relatively few detailed studies of the remediation of PCB-contaminated soils by legume-rhizobia symbionts. Here we report for the first time evidence of the reductive dechlorination of 2,4,4′-trichlorobiphenyl(PCB 28) by an alfalfa-rhizobium nitrogen fixing symbiont. Alfalfa(Medicago sativa L.) inoculated with wild-type Sinorhizobium meliloti had significantly larger biomass and PCB 28 accumulation than alfalfa inoculated with the nitrogenase negative mutant rhizobium Sm Y. Dechlorination products of PCB 28, 2,4′-dichlorobiphenyl(PCB 8), and the emission of chloride ion(Cl-) were also found to decrease significantly in the ineffective nodules infected by the mutant strain Sm Y. We therefore hypothesize that N2-fixation by the legume-rhizobium symbiont is coupled with the reductive dechlorination of PCBs within the nodules. The combination of these two processes is of great importance to the biogeochemical cycling and bioremediation of organochlorine pollutants in terrestrial ecosystems.     

冬季太平洋三种海温异常型及其对欧亚大气环流的影响

通过对冬季太平洋海温场及滞后0—6月的欧亚500hPa高度场的联合REOF相关分析发现,与500hPa环流异常相联系的冬季海温异常分布可分为三种类型:EC型、KC型和WD型,其异常中心区域分别对应于赤道中东太平洋——加利福利亚海流区、黑潮区和北太平洋西风漂流区。各型海温异常对欧亚500hPa环流具有不同的滞后影响特征,滞后0—3月的影响区主要是低纬度地区,4个月以后可达中纬度地区,尤其是对我国东部上空环流的影响。无论是中纬度海洋还是低纬度海洋均可对滞后4个月以后的东亚中纬度环流产生明显影响。      

大气负离子自动测报仪的研制

空气中负离子浓度是空气质量好坏的标志之一.为了满足国内外相关部门对测量大气负离子仪器的需求,研制开发了专利产品WIMD-A系列大气负离子自动测报仪,该自动测报仪符合相关的国家推荐标准,实现了从数据采集到传输的全部自动化、智能化,工作环境的空气湿度可以从0～100%,彻底取代了人工观测.业务运行结果表明仪器忭能稳定,工作可靠,减轻了观测人员的工作强度.     

Fractional vegetation cover estimation in heterogeneous areas by combining a radiative transfer model and a dynamic vegetation model

ABSTRACT

A fractional vegetation cover (FVC) estimation method incorporating a vegetation growth model and a radiative transfer model was previously developed, which was suitable for FVC estimation in homogeneous areas because the finer-resolution pixels corresponding to one coarse-resolution FVC pixel were all assumed to have the same vegetation growth model. However, this assumption does not hold over heterogeneous areas, meaning that the method cannot be applied to large regions. Therefore, this study proposes a finer spatial resolution FVC estimation method applicable to heterogeneous areas using Landsat 8 Operational Land Imager reflectance data and Global LAnd Surface Satellite (GLASS) FVC product. The FVC product was first decomposed according to the normalized difference vegetation index from the Landsat 8 OLI data. Then, independent dynamic vegetation models were built for each finer-resolution pixel. Finally, the dynamic vegetation model and a radiative transfer model were combined to estimate FVC at the Landsat 8 scale. Validation results indicated that the proposed method (R²?=?0.7757, RMSE?=?0.0881) performed better than either the previous method (R²?=?0.7038, RMSE?=?0.1125) or a commonly used method involving look-up table inversions of the PROSAIL model (R²?=?0.7457, RMSE?=?0.1249).