Mass Balance Study on Phosphorus Removal in Constructed Wetland Microcosms Treating Polluted River Water     

Haiming Wu  Jian Zhang  Cong Li  Jinlin Fan  Yina Zou 《洁净——土壤、空气、水》2013,41(9):844-850

A number of studies have showed that the mass removal rates of phosphorus (P) in different constructed wetlands (CWs) varied significantly, and it is essential to quantify the contributions of major P removal processes in order to improve system design. The objective of this study was to investigate the effects of vegetation, hydraulic retention time (HRT), and water temperature on P removal from polluted river water and to quantify the contributions of different P removal pathways in surface CWs. Results showed that the average total P removal rates ranged between 2.69 and 20.84 mg/(m² day) in different seasons and were influenced significantly by vegetation, HRT, and water temperature. According to the mass balance approach, plant uptake removed 4.81–22.33% of P input, while media storage contributed 36.16–49.66%. Other P removal processes such as microbiota uptake removed around 0.26–4.13%. Media storage and plant uptake were identified as the main P removal processes in surface CWs treating polluted river water. This illustrated the importance of selecting media and plants in CWs for future practical application.  相似文献   

Status of Macrobenthic Community and Its Relationships to Trace Metals and Natural Sediment Characteristics     

Ying Zhang  Zhenbo Lv  Bo Guan  Yuanjin Liu  Fan Li  Shaowen Li  Yuanqing Ma  Junbao Yu  Yunzhao Li 《洁净——土壤、空气、水》2013,41(10):1027-1034

Laizhou Bay, located in the northwest of Shandong Peninsula, has complex transitional environments between terrestrial and marine ecosystems. In the present study, a total of 122, 131, and 139 species were collected in spring, summer, and autumn 2011, respectively. Species constitutions of macrobenthos were grouped into four phyla, of which annelida were the most abundant phylum, the average biomass proportion of echinodermata was the lowest, and the proportion of important species for mollusca was the highest. The structure of the macrobenthic community showed significant differences between sites, and greater divergence was observed between the third site (S03) and other stations. The ABC plots showed that the biomass curve lay below the abundance curve, and the W‐statistic value was negative. The result of the BOPA index showed that two stations had moderate ecological status in spring and that there were two heavily polluted sites and one moderately polluted site in summer. The BIO‐ENV analyses indicated that the grain‐size fractions together with trace metals (Hg, Pb, Zn, Cu, and Cr) could be considered as the major environmental variables influencing the macrobenthic patterns. The results together demonstrated that the macrobenthic communities in Laizhou Bay were negatively affected, perhaps by the tremendous impact of heavy metals in the sediments.  相似文献   

DEM数据的高效组织     

杨程永  程新文  滕长胜 《测绘通报》2013,(10):99-101

随着DEM数据在航摄技术设计中的大量使用,DEM数据的组织和分析效率已经成为评价航线设计软件优劣的重要因素。本文介绍如何根据航摄范围快速高效地提取DEM数据并通过VC++编程实现该算法,且以具体的实际DEM数据来进行验证,最后分析具体的实例来说明该方法的适用性和可应用性。试验结果表明,该方法不仅可有效地优化软件的运行环境和提高软件的适用性,而且具有很灵活的应用性和很高的检索效率。  相似文献   

北斗与GPS数据质量对比分析     

潘林  蔡昌盛  戴吾蛟  高晓 《全球定位系统》2013,38(2)

利用空旷环境和树林环境下实测北斗和GPS观测数据,从多路径效应、周跳、数据采集率、载噪比这四个方面进行数据质量分析.通过分析发现:在树林环境采集的北斗和GPS数据均要比空旷环境采集的数据质量差,北斗的观测数据质量在树林环境下要好于GPS.  相似文献   

卡尔曼滤波粗差探测在GPS变形监测中的应用     

刘恒辉  丁健  王璠 《全球定位系统》2013,38(1):87-90,95

在GPS变形监测中,由于受到周跳、SA政策、整周模糊度解算误差及其多路径效应的影响,致使观测数据中含有粗差。用标准卡尔曼滤波方法进行数据处理时,观测数据中的粗差会在卡尔曼滤波预测残差中得到反映。通过结合标准卡尔曼滤波模型与拟准检定法检测,找出并剔除粗差,处理得到正确的结果,并列举了实例证明该方法的实用性。  相似文献   

GPS多路径效应中的EEMD时空滤波器     

徐佳  杨秋实  杨帆 《测绘科学》2013,38(3):57-58,62

根据结构动态监测中GPS多路径效应的日重复性和低频周期等特性,本文研究了一种基于集成经验模态分解(EEMD)技术的滤波方法,构造了EEMD时空滤波器。通过计算连续两天GPS动态监测数据EEMD的相关系数,提取GPS监测数据中的多路径效应。实验结果表明了该方法的有效性,为结构动态变形模态分析提供了有效数据。  相似文献   

矿区三维地质建模与地裂缝成因分析     

文晔  徐爱功  杨帆 《测绘科学》2013,38(4):43-45

为了分析在复杂地质条件下采煤引起的大规模地表裂缝的形成原因,本文以某矿区地裂缝为研究对象、数字化软件SURPAC为技术平台、岩体为主要区域变量,建立关于开采工作面、火成岩、地裂缝及断层的三维地质模型,并进行开采沉陷影响预计,通过分析裂缝成因中各相关地质条件的作用影响,得出了煤炭开采导致地下应力平衡被打破后造成地裂缝的主要因素,为预防和治理地裂缝提供了参考。  相似文献   

Defending against wormhole attack in OLSR     

Hong Liang  Hong Fan  Fu Cai 《地球空间信息科学学报》2013,16(3):229-233

OLSR (optimal link state routing) is one of the four basic routing protocols used in mobile ad hoc Networks by the MANET working group of IETF (Internet engineering task force). OLSR, a proactive routing protocol, is based on a multipoint relaying flooding technique to reduce the number of topology broadcast. OLSR uses periodic HELLO packets to neighbor detection. As introduced in Reference [1], the wormhole attack can form a serious threat in wireless Networks, especially against many ad hoc Network routing protocols and location-based wireless security systems. Here, a trust model to handle this attack in OLSR is provided and simulated in NS2.  相似文献   

Modeling and assessment of combined GPS/GLONASS precise point positioning   总被引：4，自引：2，他引：2  

Changsheng Cai  Yang Gao 《GPS Solutions》2013,17(2):223-236

A combination of GPS and GLONASS observations can offer improved reliability, availability and accuracy for precise point positioning (PPP). We present and analyze a combined GPS/GLONASS PPP model, including both functional and stochastic components. Numerical comparison and analysis are conducted with respect to PPP based on only GPS or GLONASS observations to demonstrate the benefits of the combined GPS/GLONASS PPP. The observation residuals are analyzed for more appropriate stochastic modeling for observations from different navigation systems. An analysis is also made using different precise orbit and clock products. The performance of the combined GPS/GLONASS PPP is assessed using both static and kinematic data. The results indicate that the convergence time can be significantly reduced with the addition of GLONASS data. The positioning accuracy, however, is not significantly improved by adding GLONASS data if there is a sufficient number of GPS satellites with good geometry.  相似文献   

还原成岩作用对磁性矿物的影响及古气候意义:以长江口水下三角洲岩芯YD0901沉积物为例   总被引：2，自引：0，他引：2  

郑妍  郑洪波  邓成龙  王敏杰  范代读 《第四纪研究》2012,32(4)

本文对长江口水下三角洲岩YD0901(31°11′N,122°30′E)中0～34.22m的沉积物进行高分辨率岩石磁学研究,结果表明:阶段Ⅰ (0 ～ 8m)中磁性矿物含量高,含有磁铁矿、赤铁矿及少量的硫化物;阶段Ⅱ(8.0～34.2m)中磁性矿物含量低,磁性矿物包括粗颗粒磁铁矿、赤铁矿和铁的硫化物.磁参数结果指示了沉积物垂向上氧化还原环境的改变,由还原环境(阶段Ⅱ)转为氧化环境(阶段Ⅰ).受成岩作用影响,阶段Ⅱ中的细颗粒的磁铁矿颗粒被溶解而生成铁的硫化物,但是粗颗粒磁铁矿和赤铁矿受成岩作用影响较小,可以提取原生的古气候信息.根据磁性矿物含量和矫顽力的变化在1300年至7000年之间识别出4个气候突然变冷事件,沉积物磁性矿物矫顽力反映的气候变化周期为800年和220年.  相似文献