Sedimentary Phosphorus Form Distribution and Cycling in the Littoral Subzones of a Eutrophic Lake

Algae which bloom in open water and accumulate in the littoral zones may affect the biogeochemical cycle of phosphorus in eutrophic lakes. To determine such effects, a part of the lakeshore with little allochthonous nutrient input in Taihu Lake, China was selected for this field study. Distinct differences in sedimentary P forms were found among the different littoral subzones. The surface sedimentary total phosphorus (TP) content was 655 mg/kg in the eulittoral subzone and 631 to 641 mg/kg in the infralittoral subzone. Both were much higher than that in the profundal zone (410 mg/kg). Calcium‐bound P (Ca‐P) was significantly correlated to exchangeable P (Ex‐P), and they both had the highest contents in the infralittoral subzone and the lowest in the profundal zone. The aluminum‐ and iron‐bound P (Al‐P, Fe‐P) contents decreased from land to water along the ecotone section. Lower Fe/P ratios and higher Al‐P/Fe‐P ratios appeared in the infralittoral subzone, as compared with the profundal zone. This suggested that the accumulated algae could lead to a great deposit of P in the littoral zones. However, the active sedimentary P form transformation in the littoral zones would also result in a partial release of the accumulated P to the overlying water.     

陇南山区农业气候资源特征与开发利用

分析了甘肃陇南山区农业气候资源的分布特征及其水平、垂直差异,提出了合理开发利用的农业决策建议,指出应利用资源优势建立名特优小商品生产基地。     

The Characteristics of Atmospheric Ice Nuclei Measured at Different Altitudes in the Huangshan Mountains in Southeast China简

The concentration of ice nuclei （IN） and the relationship with aerosol particles were measured and analyzed using three 5-L mixing cloud chambers and a static diffusion cloud chamber at three altitudes in the Huangshan Mountains in Southeast China from May to September 2011.The results showed that the mean total number concentration of IN on the highest peak of the Huangshan Mountains at an activation temperature （Ta） of-20℃C was 16.6 L-1.When the supersaturation with respect to water （Sw） and with respect to ice （Si） were set to 5％,the average number concentrations of IN measured at an activation temperature of-20℃C by the static diffusion cloud chamber were 0.89 and 0.105 L-1,respectively.A comparison of the concentrations of IN at three different altitudes showed that the concentration of IN at the foot of the mountains was higher than at the peak.A further calculation of the correlation between IN and the concentrations of aerosol particles of different size ranges showed that the IN concentration was well correlated with the concentration of aerosol particles in the size range of 1.2-20 μtm.It was also found that the IN concentration varied with meteorological conditions,such as wind speed,with higher IN concentrations often observed on days with strong wind.An analysis of the backward trajectories of air masses showed that low IN concentrations were often related to air masses travelling along southwest pathways,while higher IN concentrations were usually related to those transported along northeast pathways.     

旅游地传统饮食文化原真性感知对满意度与行为意向的影响——以宏村臭鳜鱼为例

在区分地方饮食与传统饮食概念的基础上,选择宏村传统饮食臭鳜鱼作为研究对象,通过对就餐环境、服务、食物3个原真性维度和满意度与行为意向2个维度,构建Amos结构方程模型,探究游客对传统饮食文化的原真性感知及其对旅游地就餐满意度和行为意向的影响。结果显示,3个维度的原真性均对满意度呈显著、直接、正向影响,对行为意向呈显著、间接、正向影响;其中,环境原真性对就餐满意度影响最大,其次为服务原真性,最后为食物原真性。研究认为,即使体验对象是与原真性关联紧密的传统饮食,大众游客仍更关注整体就餐环境和服务氛围,食物本身对满意度的影响最低。游客需求引发传统饮食文化舞台化重塑,并呈现“去传统化”与“去地方化”特征,旅游地饮食文化塑造对环境的关注大于食物,但当地居民更加关注食物本身的口味,主客关注差异和食物生产过程的游客需求导向引发当地居民对舞台化饮食的认同度降低。未来旅游地要充分考虑传统饮食的特殊性,重塑让游客与本地居民更加满意的饮食文化。     

黄河上游官亭盆地红粘土层成因机制再探讨

位于官亭盆地的喇家史前灾难遗址被毁原因是近年来人们争论的焦点。笔者在野外调查和实验测试分析的基础上,对官亭盆地二级阶地上沉积的红色粘土层来源、成因机制进行了再探讨,揭示了山洪泥石流对官亭盆地喇家遗址的影响,以期为山间盆地区居民正确制定防灾减灾措施提供地质依据。主要取得了以下认识:1)官亭盆地剖面2.45m厚的红色粘土层其粒度特征以第二组分为优势组分,其中值粒径为9~11μm; 磁化率值主要分布在20×10-8~40×10-8 m3/kg之间; 2)该红色粘土层与积石峡峡谷区的湖相地层在发育年龄、颜色、粒度、磁化率、土体质地结构等方面具有明显区别,反映了二者不同的成因机制,红色粘土层与积石峡堰塞湖溃决无关; 3)官亭盆地北侧由于地震等作用形成的山体古崩塌、古滑坡和第三系松散粘土物质被强降水近距离冲刷搬运堆积在山前坡地,遗址毁灭的洪水来自北侧岗沟等沟谷,而非黄河泛滥的洪水; 4)官亭盆地红粘土的成因可能是:地震诱发滑坡、崩塌,同时造成山体疏松,在暴雨或持续降水作用下,滑坡崩塌堆积物和山体松散物质被洪水沿沟谷携带到沟口及地势较低的黄河二级阶地沉积,地震后发生的山洪泥石流灾害造成了喇家遗址的彻底毁灭。     

多因素控制的城镇地震灾害应急处置模型研究

随着城镇化水平的快速提高,地震灾害高风险暴露城镇数量将不断增加,震后有效的应急处置尤为重要。而当前城镇的地震应急处置主要依据平时制定的地震应急预案开展,缺乏针对性与可操作性。本文以提升城镇地震灾害应急处置能力为目的,总结以往城镇地震应急处置案例,提炼城镇地震灾害应急处置流程,结合城镇特殊的社会经济、自然地理等特点,在分析影响地震灾害应急处置关键因素的基础上,按地震烈度的不同,研究构建了具有区域特征且操作性较强的城镇地震灾害应急处置模型,为城镇地震应急处置的科学化、规范化提供了参考。     

沙子口湾海岸侵蚀原因及防治对策研究

通过实测水文资料、岸滩冲淤变化规律和泥沙动态研究沙子口湾近３０ａ来的变化,分析湾顶海滩侵蚀的原因,对现有的海岸工程进行调查,研究海岸防护对策,分析海岸防护工程的可行性。     

Characteristics of coseismic water level changes at Tangshan well for the Wenchuan MS8.0 earthquake and its larger aftershocks

Coseismic water level changes which may have been induced by the Wenchuan M_S8.0 earthquake and its 15 larger aftershocks (M_S≥?5.4) have been observed at Tangshan well. We analyze the correlation between coseismic parameters (maximum amplitude, duration, coseismic step and the time when the coseismic reach its maximum amplitude) and earthquake parameters (magnitude, well-epicenter distance and depth), and then compare the time when the coseismic oscillation reaches its maximum amplitude with the seismogram from Douhe seismic station which is about 16.3 km away from Tangshan well. The analysis indicates that magnitude is the main factor influencing the induced coseismic water level changes, and that the well-epicenter distance and depth have less influence. M_S magnitude has the strongest correlation with the coseismic water level changes comparing to M_W and M_L magnitudes. There exists strong correlation between the maximum amplitude, step size and the oscillation duration. The water level oscillation and step are both caused by dynamic strain sourcing from seismic waves. Most of the times when the oscillations reach their maximum amplitudes are between S and Rayleigh waves. The coseismic water level changes are due to the co-effect of seismic waves and hydro-geological environments.     

盾构隧道局部长期渗水对隧道变形及地表沉降的影响分析

研究表明,盾构隧道长期渗水会造成地表及隧道严重沉降。针对盾构隧道局部渗流难以模拟的现状,首先提出了一种既符合盾构隧道刚度要求又能实现局部接头渗水的计算方法;在稳定渗流状态对应的相同渗流量的前提下,对比分析了管片在不同接头渗水条件下隧道周围土体孔压分布、地表和隧道沉降以及隧道变形规律。分析结果表明,盾构隧道渗水接头的位置不同,孔压分布、地表和隧道沉降以及隧道的变形均有明显差异;接头位置越靠近隧道底部,渗水导致的孔压减小越显著,造成的地表及隧道沉降越显著。接头渗水不但会使隧道发生横向椭圆化变形,还会引起隧道左右两侧受力不平衡,从而造成隧道水平侧移。通过对比表明,采用接头渗水和传统的衬砌均质渗水得到的孔压分布、沉降及隧道变形规律均有显著不同;不考虑隧道局部渗水特点会对隧道结构长期性态的认识产生偏差。     

不同砾石覆盖度戈壁床面风蚀速率定量模拟

通过风洞实验,利用称重传感器自动记录风蚀观测样方重量变化过程,对供沙条件下不同砾石覆盖度戈壁床面风蚀速率进行了定量模拟研究。结果表明:砾石覆盖度是影响戈壁风蚀速率的关键因子,戈壁床面风蚀速率随砾石覆盖度增加按指数规律递减。各实验风速下,砾石覆盖度>50%时,戈壁床面风蚀速率随砾石覆盖度增加而减小量有限,甚至无风蚀发生;而盖度从10%到50%时,风蚀速率显著减小。因此,两种实验粒径砾石(3 cm与4 cm)至少在50%盖度时才能达到较好的风蚀防治效果。戈壁风蚀防护机理主要是砾石覆盖度的增加增大了砾石间沙粒的临界起动剪切风速,而且减少了作用在砾石间可蚀地表的剪切压。与沙质对照床面相比,10%~90%砾石盖度戈壁床面沙粒临界起动剪切风速增大了0.8~3.4倍,只有0.5％~28%的剪切压作用在砾石间可蚀地表。