物联网在海洋相关领域研究与应用进展

随着科学技术的发展,物联网正成为海洋领域的前沿研究内容之一。在海洋观测领域,利用物联网构建海洋环境立体观测体系,对于研究全球气候变化、海上态势感知、海洋灾害预报等具有重大意义;在海岛生态监测领域,利用海岛生态物联网系统可以实现海岛生态的长期实时监测;在海洋牧场监测领域,利用物联网可以实现海洋牧场的环境、生物等要素的实时监测;在智能船舶领域,利用物联网可以实现船舶自身、港口、物流的信息自动感知。文章探讨了物联网在上述4个领域的研究与应用进展,以期进一步促进物联网在我国海洋信息化中的应用与发展。     

Field application at a DNAPL-contaminated site in Nanjing and discussion of a source search algorithm based on stochastic modeling and Kalman filter

Delineation of contaminant sources is vital for successful groundwater and soil remediation. With reliable source information, remediation time and cost can be dramatically reduced. An optimal contamination source search strategy incorporating Monte Carlo method, Kalman filtering and fuzzy set theory was applied to a contaminated site in Nanjing to define suspected multiple DNAPL source locations. Using the available nine sample data, the algorithm identified sources #1 and #4 as true sources, and sources #5 and #6 as false ones. The algorithm results for sources #2 and #3 were inconclusive. Three numerical experiments based on specific site conditions were then designed and conducted to determine the influencing factors on the algorithm’s convergence in sources #2 and #3. The numerical experiments tested the effect of multiple sources, the effect of the sources location in relation to the groundwater flow direction and the effect of a low permeability field on the convergence of the algorithm. Based on the numerical experiments and an understanding of the manufacturing site operations, sources #2 and #3 are likely to be true sources. Their moderate weights have been stabilized due to the existence of multiple true sources and the scarcity of informative sampling data, caused by the low permeability field. The moderate weight value of source #3 also includes a contribution from an overlapping plume caused by the sources’ parallel-to-flow layout pattern. It can be concluded that the algorithm works best for high permeability sites where potential source locations are scattered and source location patterns are orthogonal to the groundwater flow.     

时变补给条件下河渠间潜水的一维非稳定运动

针对河渠间潜水的一维非稳定运动,考虑了补给强度的时变性,根据Boussinesq方程的第一线性化方法,应用Duhamel原理得到了方程的解析解,进一步得出补给强度为指数函数和三角函数的潜水位计算公式。通过算例分析补给强度指数增加、指数衰减和正弦函数变化条件下潜水面的变化特征,指数增加条件下潜水位单调增加,分水岭从高水位一侧向河间地块中部移动;指数衰减条件下潜水位先增大,后减小,具有一个峰值,分水岭先从高水位一侧向河间地块中部移动,之后随补给强度减弱返回到高水位河渠;正弦函数变化条件下潜水位表现出周期性起伏变化,且水位对补给的响应具有明显的时滞性,分水岭在高水位河渠与河间地块中部之间往复移动。研究结果可为量化分析地下水系统对气候变化的响应以及地表水地下水转化规律等问题提供理论依据。     

Modeling the Phase Transition Associated with Melting Snow in a 1D Kinematic Framework: Sensitivity to the Microphysics

A simple 1D kinematic cloud model coupled to a two-moment bulk microphysics scheme is used to perform quasi-idealized simulations of snow, with a prescribed upper boundary snow field based on observed radar reflectivity and temperature, falling into a low-level melting layer. The model realistically simulates the formation of a nearly isothermal layer below the melting level, the surface precipitation rate, and the phase transition from liquid to solid, consistent with observations for this case. A series of test runs is performed to examine the sensitivity of modeling the timing and duration of the phase transition period to details of specific parameterization aspects related to snow in the microphysics scheme. The sensitivity tests include varying the number of prognostic moments, the mass–diameter relation, the fall velocity–diameter relation, the treatment of aggregation, and the lower limit for the slope of the size distribution. It is shown that the simulated transition period, for such a case with the initial melting level being close to the surface, can be quite sensitive to model parameters specified within realistic ranges and/or ranges within our physical understanding.     

石碑塬滑坡黄土液化特征及其影响因素研究

石碑塬滑坡是1920年海原地震触发的大型黄土流滑,认识其破坏特征与发生机制对于黄土边坡长距离液化失稳机制的研究非常重要。对石碑塬黄土滑坡的调查和研究表明,饱和黄土或高含水率黄土具有很高的液化势和流态破坏势,在强震作用下,饱和黄土易发生液化或流滑。对石碑塬滑坡的7组原状黄土样品进行振动三轴剪切试验,并结合其微观特征分析,探讨了循环振动荷载作用下的饱和黄土孔隙水压力-应变增长模型,分析了振动液化过程中液化应力比与黄土粒度组成、土体微观结构参数及饱和度之间的关系。结果表明：黏粒含量越低,振动作用下饱和黄土孔隙水压力响应越快,液化应力比越低;黄土孔隙比越大,孔隙结构分形维数越大,液化应力比越低,振动液化后黄土孔隙分形维数降低,结构较液化之前更为致密;饱和度对黄土粒间胶结物质的赋存状态及黄土结构强度影响很大,同一土体饱和度越高,溶滤于孔隙水中的离子浓度越高,土体粒间接触点（或胶结点）越容易发生断裂,使得黄土结构强度降低,液化应力比降低。     

Rocky desertification and its causes in karst areas: a case study in Yongshun County,Hunan Province,China

Rocky desertification, a process of land degradation characterized by soil erosion and bedrock exposure, is one of the most serious land degradation problems in karst areas, and is regarded as an obstacle to local sustainable development. It is well known that human activities can accelerate rocky desertification; however, the effects of climate change on rocky desertification in karst areas are still unclear. This study focused on the effects of temperature and precipitation changes and human activities on rocky desertification in karst areas to determine the impacts of climate change and human disturbances on rocky desertification. Areas of different level of rocky desertification were obtained from Landsat TM (1987) and Landsat ETM+ (2000) images. The results show that, although the total desertification area increased by only 1.27% between 1987 and 2000, 17.73% of the slightly desertified land had degraded to a moderate or intense level, 2.01 and 15.71%, respectively. Meanwhile, between 1987 and 2000, the air temperature increased by 0.7°C, and precipitation increased by 170 mm. Statistical results indicate that the increase in precipitation was caused by heavy rainfall. In addition, under the interactive influences of heavy rainfall and temperature, the average karst dissolution rate was about 87 m³ km⁻² a⁻¹ during the 14 years in the study area. Further analysis indicated that rocky desertification was positively related with the increase in temperature and precipitation and especially with the heavy rainfall events. Climate change accelerated rocky desertification in the karst areas. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

柿竹园矿床S同位素地球化学研究

通过硫同位素低温平衡系统,分析平衡条件下δ~(34)S_(H_2S)与δ34S热液偏差,获得成矿流体的含硫组分以H_2S为主。成矿阶段δ~(34_S值变化范围狭窄,呈塔式分布,具有岩浆硫特征,柿竹园矿床矿石中的硫来自岩浆流体,即千里山花岗岩。硫同位素fO_2—pH值关系图,投影得出350℃时,fO_2为-28.3~-31.5;250℃时,fO_2为-35.4~-37.5。     

Identification and characterization of the Vibrio anguillarum prtV gene encoding a new metalloprotease

We cloned and sequenced a prtV-like gene from Vibrio anguillarum M3 strain. This prtV gene encodes a putative protein of 918 amino acids, and is highly homologous to the V. cholerae prtV gene. We found that a prtV insertion mutant strain displayed lower gelatinase activity on gelatin agar, lower protease activity against azocasein, and lower activity for four glycosidases. This prtV mutant strain also had increased activity for two esterases in its extracellular products, as analyzed by the API ZYM system. In addition, the prtV mutant strain exhibited decreased growth in turbot intestinal mucus and reduced hemolytic activity on turbot erythrocytes. Infection experiments showed that the LD₅₀ of the prtV mutant strain increased by at least 1 log compared to the wild-type in turbot fish. We propose that prtV plays an important role in the pathogenesis of V. anguillarum.     

土地覆盖对岩溶地下河碳汇的影响——以广西打狗河流域为例

以广西打狗河为例,对比分析河流东、西两岸地下河的土地覆盖差异及其对岩溶碳汇的影响。打狗河东岸林地占56.13%,耕地占15.15%;而西岸林地、耕地分别只占20.8%、12.95%。但西岸的裸岩和荒地比例大,分别占29.57%和25.95%,而东岸分别占14.19%和10.98%。植被和土壤覆盖差异导致了东、西两岸碳循环的地球化学指标有明显的差异,东岸地下河水的HCO3-、Ca2+、PCO2(平均分别是233.71mg/L、85.5mg/L、909.46Pa)明显高于西岸(分别为177.26mg/L、64.65mg/L、257.37Pa),而东岸的SIC、pH值(分别为0.12和7.40)又低于西岸(分别是0.38和7.85)。因此,东岸有更强的岩溶动力条件,东岸地下河的平均碳汇强度比西岸高14%,其中,东岸下桥地下河的碳汇强度是西岸旦峒地下河的3.7倍。东西岸地下河水的δ13CDIC、TOC资料也进一步证明了土地覆盖条件对地下河岩溶碳汇具有重要的影响。      

Luminescence dating of baked earth and sediments from the Qujialing archaeological site,China

The Qujialing site is a representative Neolithic archaeological site in the middle reaches of the Yangtze River, China. Absence of suitable material for radiocarbon dating in this region makes the timing of the similar sites difficult. Here we applied optically stimulated luminescence (OSL–SAR) and thermoluminescence (TL–SAR) techniques to date the archaeological and natural deposits from the Qujialing site with known age, testing the techniques on samples at archaeological sites in this region. The results showed that the luminescence properties of quartz from sediment and baked earth samples are very similar. The quartz OSL ages obtained for a sediment sample and a baked earth sample from the cultural layer are 5.4 ± 0.3 and 5.1 ± 0.3 ka, respectively. The quartz TL age of the baked earth sample is 5.6 ± 0.5 ka. These dates are consistent with the calibrated radiocarbon ages (4.9 ± 0.1 and 5.1 ± 0.1 ka cal BP (±1σ)) of the two charcoal samples from the cultural layer at a nearby locality, and are also in agreement with the age of Qujialing culture period. The results indicate that the OSL dating techniques can be applied to date similar archaeological sites in the middle reaches of the Yangtze River, China.