Comparison of ecophysiological characteristics between introduced and indigenous mangrove species in China

Due to its rapid growth, the introduced mangrove species Sonneratia apetala from Bangladesh has been widely used in mangrove restoration in southeastern China since 1985. As an indigenous mangrove species in Hainan, China, Sonneratia caseolaris was also planted in Guangdong Province for afforestation purposes. Both species have developed well in their new habitats, but their ecophysiological differences with the native mangrove species have not been studied. In this study, leaf gas exchange, water and nitrogen use efficiencies of two Sonneratia species were compared with those of selected native mangrove species (Avicennia marina, Aegiceras corniculatum, Kandelia candel, and Excoecaria agallocha) in Hainan and Shenzhen. The introduced S. apetala maintained lower carbon assimilation rate (A) and photosynthetic nitrogen use efficiency (PNUE) than the indigenous S. caseolaris. In Shenzhen, the two introduced Sonneratia had comparable photosynthetic rates and water use efficiency (WUE) with the native mangrove species, except that PNUE in S. caseolaris was significantly higher than in the native mangrove species. The two Sonneratia species showed significant overlap in PNUE and long-term WUE. Photosynthetic parameters derived from leaf photosynthetic light–response curves and A–C_i curves also suggested lower carbon assimilation capacities for the introduced Sonneratia than for the native mangrove species in both study sites. The lower light compensation point (LCP) of two introduced Sonneratia in both study sites also indicated a better adaptation to a low light regime than the native mangrove species. The results of photosynthetic capacities indicated that the introduced mangrove species have little competitive advantage over local native mangrove species in their respective new habitats.     

Methane hydrate formation comparisons in media with and without a water source supply

Water is a necessary element during gas hydrate formations. Therefore, by analyzing water depletion changes in media, the reaction characteristics of methane hydrate in media can be studied. In this study, two water sources supplying some liquid water which may be consumed by the methane hydrate formation reactions were designed and assembled. Using them, the full formation processes of methane hydrate was studied. Experimental results show the following： If heat released from nucleation reaction of methane hydrate is diffused rapidly, the nucleation ratios will be enhanced discernibly. While the hydrate is formed, a force is generated that sucks fresh water from the source into the vicinity of the hydrate, slowing down the cementation process and causing some hydrate grain dissociation. As a result of cementation differences, the hydrate reaction processes with different water sources present linear or quadratic equation characteristics. After a few repeated dissociation and formation processes of some hydrate grains caused by the fresh water, the gas amounts contained in hydrate will be significantly enhanced.     

Groundwater and surface water interactions in an alluvial plain, Tuul River Basin, Ulaanbaatar, Mongolia

Drinking water supplies in Ulaanbaatar, the capital of Mongolia, are completely dependent on groundwater sourced from pumping wells located in an alluvial plain of the Tuul River which flows through Ulaanbaatar. The interaction between groundwater in the alluvial plain and river surface water was investigated using a hydrological and multi-tracers approach. The observed groundwater contour map clearly shows that the Tuul River recharges the floodplain groundwater and groundwater flows from east to west. The similarity of chemical and stable isotopic compositions suggests that groundwater is mainly recharged by Tuul River water in the vicinity of the river. In addition, considering groundwater contours and chemical composition, groundwater in the northern and southern mountain sides contribute to floodplain groundwater. Stable isotopic information suggests that winter season precipitation also contributes to the groundwater, because groundwater in a specific region has a considerably lower isotopic ratio. Using the End Member Mixing Analysis applying oxygen-18, SiO₂ and HCO₃ ^- as tracers, the contribution ratios of the Tuul River, groundwater in the northern and southern mountain regions, and winter season precipitation to floodplain groundwater are estimated to be 58% to 85%, 1% to 54%, 0% to 16%, and 0% to 12%, respectively.     

不同无机晶须/PVC复合材料力学性能的研究

采用溶液共混法制备出硼酸镁晶须(MBOw)、硼酸钙晶须(Ca BOw)、硼酸铜铝晶须(Cu Al BOw)、碱式硫酸镁晶须(MOSw)、碳酸钙晶须(Ca CO3w)及硫酸钙晶须(Ca SO4w)增强的PVC复合材料,研究不同晶须对PVC力学性能的影响。采用扫描电镜分析PVC复合材料的拉伸断面及晶须分散情况。结果表明,除MOS外其它晶须对PVC的拉伸强度和弹性模量有不同程度的提高,MBOw对PVC复合材料的增强效果最显著,当MBOw含量为20%时,所得复合材料力学性能最佳,拉伸强度和弹性模量与纯PVC比较分别提高了38.08%和71.43%。     

Effect of removing small (<150?μm) chironomids on inferring temperature in cold lakes

Sieving samples for chironomid analysis with a 150 μm mesh was shown to greatly reduce sample preparation time, and use of only larger specimens did not affect chironomid-inferred salinities in African lakes. Here, we tested if this method is suitable for temperature reconstruction in colder lakes at higher latitudes. Removal of specimens <150 μm in two training sets, one from Canada and one from Sweden, had little impact on the performance statistics of the calibration models. Chironomid abundance, however, decreased greatly because more than half of the head capsules in assemblages were <150 μm. This had major impacts on the temperature reconstructions. Inferences were on average 2°C warmer with the modified models (all specimens >150 μm) than those obtained with the full model (all specimens >100 μm). General patterns of temperature change were also altered. For Lake 7 on Southampton Island, Canada, a cooling trend was reconstructed with the full Canadian model while the modified Canadian model yielded a warming trend. When only specimens >150 μm were used, two to three times more wet sediment was needed to obtain a sufficient number of head capsules. These results indicate that, in cold lakes (mean July/August air temperature ≤11°C), large proportions of head capsules are <150 μm, and sieving the samples in a 150 μm mesh leads to altered temperature reconstructions.     

论黄河上游多民族经济开发区资源开发战略

本文在分析黄河上游多民族经济开发区资源特点的基础上，论证了经济区资源开发模式及开发战略，并就经济蛆内各区域非平衡开发及开发时序提出了一些见解。     

现代浮游有孔虫对南海西南部上升流的响应

现代夏季风系统导致了南海西南部（越南岸外）上升流的发育,但浮游有孔虫对夏季上升流的响应如何尚缺乏实测资料,这不利于准确地利用有孔虫来重建古上升流的活动进而反演过去夏季风的强度变化。本研究利用2014年4月14日至11月1日布放于南海西南部夏季上升流区的时间序列沉积物捕获器材料,详细鉴定并定量统计了其所含浮游有孔虫类型。通过分析样品中浮游有孔虫各属种的通量和百分含量变化,结合区域气候环境资料,探讨南海西南部夏季上升流区浮游有孔虫对夏季风的响应,为古上升流与夏季风研究提供现代依据。研究结果表明初级生产力是控制上升流区浮游有孔虫通量变化的首要因素,喜营养种在上升流发育期增多而寡营养种含量下降。因此高表层生产力指示种,如Neogloboquadrina dutertrei可能是追溯南海西南部夏季上升流变化最可靠的指标。

     

A STUDY ON TYPHOON MOVEMENT PART Ⅲ:EFFECT OF THE HORIZONTAL MOMENTUM EXCHANGE BETWEEN TYPHOONS AND ENVIRONMENT

Two semi-asymmetric flow patterns of typhoons are chosen to qualitatively determine the effect of exchange of horizontal momentum between inflow and outflow layers and the environment on the motion of typhoons. The results show that only the asymmetric flow component (residual after azimuthal mean flow has been removed) could cause a net momentum input into or output from a typhoon and therefore contribute to the changes in speed and direction of the typhoon movement. A typhoon with major inflow and/or outflow channels on its right (left) side would tend to accelerate and turn left (decelerate and turn right); On the other hand, a typhoon with major inflow and/or outflow channels in the rear (front) semicircle would tend to accelerate and turn right (decelerate and turn left).     

基于Matlab的断裂带温泉水地球化学特征及地震活动性研究

基于Matlab开发出地下流体分析软件,对比分析了甘肃西秦岭北缘的武山、街子和清水温泉水化学组分特征;初步分析了温泉水水质类型、补给来源、水-岩平衡状态以及循环深度,并讨论了温泉水深循环对地震活动性的影响.研究表明温泉水均为大气降水成因,其水化特征受围岩的控制作用;清水温泉水的成熟度没有武山和街子温泉水高.地下水循环深度较浅的武山温泉和街子温泉水化类型属于Na-HCO3·SO4·Cl,所处断裂的地震活动频繁;地下水循环深度较深的清水温泉水化类型属于Na-SO4·Cl,所处断裂的地震活动性弱.     

Lake Area Changes and the main causes in the hinterland of Badain Jaran Desert during 1973–2010, China

Lake area information in the Badain Jaran Desert in 1973, 1990, 2000, and 2010 was obtained by visual interpretation and water index analysis of remote sensing images, based on the spatial and temporal characteristics of lake area changes during 37 years. Results indicated that the number of lakes declined from 94 to 82 and the total surface area was reduced by 3.69 km² during 1973–2010. The desert lake area reduced by different degrees in different periods, but this occurred most rapidly during 1973–1990. According to the statistics of lake area changes, lake area decreases mainly occurred in the lakes with areas less than 0.2 km², while the areas of lakes greater than 0.9 km² only fluctuated. The changes of lake areas were probably due to changes in the quantity of underground water supplies rather than the effects of local climate change or human factors.