城市生态地貌学：介绍地貌学的一个新分支

城市生态地貌学是地理学的一个新分支,又是城市学、生态学、地貌学的边缘学科,它研究作为生态因子之一的地貌和其他各因子之间的关系以及在整个生态系统中的作用和地位。在城市生态地貌营力中,特别重视人为迭加地貌营力的作用。     

Marine bacterium strain screening and pyrethroid insecticide-degrading efficiency analysis

A pyrethroid insecticide-degrading bacterium, strain HS-24, was isolated from an offshore seawater environment. The strain, which can degrade cypermethrin(CYP) and deltamethrin(DEL), was identified as Methylophaga sp. The optimal culture and degradation conditions for CYP and DEL by strain HS-24 is pH 7 at 28°C. Under optimum culture conditions, strain HS-24 exhibited a broad degradation concentration range of 100, 200, 400, 600, and 800 mg/L for CYP and DEL. The metabolic intermediates were analyzed by NMR, which provided strong evidence that CYP and DEL removal occurred mainly because of a biological process. The toxicity of the degradation products of strain HS-24 was studied simultaneously by measuring the light output of the luminescence bacterium. This demonstrated that the biodegradation ability of strain HS-24 significantly decreased the toxicity of CYP- and DEL-contaminated aquaculture seawater. Finally, the findings of this paper indicate that strain HS-24 is thus revealed as a biological agent for the remediation of marine aquatic environments.     

Factors acquisition and content estimation of farmland soil organic carbon based upon Internet of Things

Aiming at the shortage of sufficient continuous parameters for using models to estimate farmland soil organic carbon (SOC) content, an acquisition method of factors influencing farmland SOC and an estimation method of farmland SOC content with Internet of Things (IOT) are proposed in this paper. The IOT sensing device and transmission network were established in a wheat demonstration base in Yanzhou Distict of Jining City, Shandong Province, China to acquire data in real time. Using real-time data and statistics data, the dynamic changes of SOC content between October 2012 and June 2015 was simulated in the experimental area with SOC dynamic simulation model. In order to verify the estimation results, potassium dichromate external heating method was applied for measuring the SOC content. The results show that: 1) The estimated value matches the measured value in the lab very well. So the method is feasible in this paper. 2) There is a clear dynamic variation in the SOC content at 0.2 m soil depth in different growing periods of wheat. The content reached the highest level during the sowing period, and is lowest in the flowering period. 3) The SOC content at 0.2 m soil depth varies in accordance with the amount of returned straw. The larger the amount of returned straw is, the higher the SOC content.     

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An efficient algorithm for assignment of flow direction over flat surfaces in raster DEMs based on distance transform

Flat surfaces or areas with no local gradient are general types of terrain in raster Digital Elevation Models (DEMs). When a DEM is used for automated hydrological analysis, it is necessary to assign flow directions over flat surfaces. This paper presents an improved algorithm for assigning flow directions over flat surfaces that builds on earlier work and offers efficiency improvements. The improved algorithm use distance transform method to calculate the distance values of cells in flat surfaces towards lower terrain and away from higher terrain, which can replace the recursive process in the earlier algorithm by a linear process, and reduce random data access. Furthermore, the improved algorithm assigns weights with different values and signs to the two distance values to guarantee that all flat surfaces are drained, which avoids the need to label each flat surface using the flood-fill algorithm in the earlier work. Comparisons of speed indicate that the improved algorithm is more efficient in assigning flow directions over flat surfaces.     

十堰台数字化水管仪倾斜潮汐观测质量评定

对十堰台的数字化水管仪2007-2010年倾斜潮汐观测资料进行全面质量评定后发现,运行3年以来的倾斜潮汐观测资料连续可靠,仪器工作正常稳定,零漂与年变幅等指标均在稳定范围内.长水管系列调和分析结果表明:倾斜潮汐观测在资料精确度、连续性和可用率3方面己接近国际同类水平,有些指标已超过国内优秀台站观测水平.倾斜资料于200...     

基于模拟退火优化的海马齿生长参数确定

为确定海马齿生长的相关参数,对海马齿进行了室内水培实验,连续监测海马齿生长及生态因子状况。考虑营养盐循环,基于一级衰减模式构建海马齿生长模型。使用基于单纯形实验设计的Morris法进行全局定性灵敏度分析发现,对所有状态变量均敏感的参数为氨氮硝化率和有机氮矿化常数,表明所构建模型主要由氮的循环系统所支配;最适光照是对海马齿生长最为灵敏的参数,光照是影响海马齿生长的最主要生态因子。以各状态变量的最大均方误差为代价函数,使用模拟退火算法对模型参数进行优化及确定,选取多指标对模型进行评估。结果表明,模拟值可以很好地拟合实测值,最大平均绝对百分误差为5.023%;对参数分析发现,海马齿对硝酸盐氮的吸收具有一定的偏向性,对磷具有较高的耐受性;海马齿生长速率较快,具有一定的开发前景。     

北江流域汛期降水结构变化特征

选取北江流域18雨量站1961—2017年逐日降水数据,采用降水发生率、降水贡献率指标,利用Mann-Kendall法进行变化趋势检验,分析流域汛期（3—8月）不同历时、不同等级降水结构的时空变化特征,结果表明：1）汛期降水发生率随降水历时的增加大致呈指数形式递减,其中1~4 d历时降水发生率合计69.88%;降水贡献率随降水历时的增加而先增加后减小、到≥10 d历时又显著增加。降水贡献率的空间差异主要表现为历时2~4 d与历时≥10 d在北部与东南部反向变化。2）降水发生率随降水等级的增加而减小,其中小雨发生率约占65%;西部大雨贡献率偏高;东南部暴雨贡献率偏高,其中清远、佛冈站约为39%。3）中短历时（1~6 d）降水发生率呈不显著下降趋势,而贡献率呈不显著上升趋势;长历时（≥7 d）降水发生率、贡献率均呈显著下降趋势。各等级降水变化趋势方面,小雨、中雨发生率、贡献率不显著下降,大雨、暴雨发生率、贡献率不显著上升。     

淡水产品中微囊藻毒素固相萃取-高效液相色谱检测方法的建立

研究利用固相萃取-高效液相色谱技术检测淡水产品中的微囊藻毒素MC-LR和MC-RR.样品经80％甲醇水溶液提取后,以固相萃取小柱进行净化,氮吹浓缩后以高效液相色谱进行分析.以65％甲醇水溶液(含0.05％三氟乙酸)为流动相,经C18反相色谱柱分离,以紫外检测器进行定量分析.线性定量范围0.1～2.0μg/g,检出限0....