共查询到20条相似文献，搜索用时 31 毫秒
1.
Peter Haase Susanne Lohse Steffen Pauls Karin Schindehütte Andrea Sundermann Peter Rolauffs Daniel Hering 《Limnologica》2004,34(4):349-365
In the past, no single standardised method for sampling and sorting benthic macroinvertebrates has been implemented in Germany. Therefore, we tested the suitability of two common sorting protocols, RIVPACS and AQEM/STAR, by taking samples with each protocol at 44 sampling sites. Our results reveal that different methods deliver slightly different assessment results. Moreover these two methods differ in costs. Although the AQEM/STAR protocol takes longer than the RIVPACS protocol, we favoured the AQEM/STAR protocol because of its higher level of standardisation. In order to limit costs to an acceptable level, a modification of the AQEM/STAR protocol (MAS method) is developed. This method is highly standardised, gives stable assessment results and is relatively inexpensive (€ 224.00 for processing of an average sample). A detailed protocol of the newly developed method is given. 相似文献
2.
Peter Haase Steffen U. Pauls Christine H.M. Engelhardt Andrea Sundermann 《Limnologica》2008,38(1):14-22
In the STAR/AQEM protocol microhabitats covering less than 5% of the sampling area were neglected. Driven by an ongoing discussion on the importance of these underrepresented microhabitats we tested the influence of sampling them. We investigated 48 streams representing 14 different stream types from all over Germany. Macroinvertebrates of underrepresented microhabitats were sampled in addition to the STAR/AQEM protocol. To ensure the method remains feasible in routine monitoring programmes the total sampling and sorting effort of additional sampling was limited to 20 min. Particularly those taxa were picked, which were not recognised during the routine STAR/AQEM sorting.To identify the effect of additional sampling on stream assessment results, we calculated the stream type-specific Multimetric Index (MMI) with the “main” and the “main+additional” data for each sample. The mean and median difference in MMI values between “main” and “main+additional” samples was 0.02 and 0.01, respectively. In seven of 48 samples (14.6%) a different ecological quality class was calculated with the “main+additional” dataset. Regarding common metrics within the MMI as well as intercalibration metrics differences between “main” and “main+additional” samples were analysed. The values differed most in richness metrics (e.g., number of EPTCBO Taxa, number of Trichoptera Taxa). The results of the present study show that additional sampling of underrepresented microhabitats could alter multimetric assessment results. 相似文献
3.
利用HD-6型多功能自控氡室, 配合国际标准计量仪器AlphaGUARD PQ2000Pro测氡仪, 分别采用循环采样和负压采样两种方式, 对FD-125氡钍分析器的3个闪烁室进行校准实验, 计算3个闪烁室K值和相对固有误差。 结果表明: 循环采样方式得到的闪烁室K值比负压采样方式小, 负压采样方式得到的K值偏大, 已经接近《地震水文地球化学观测技术规范》要求的闪烁室K值的极限。 循环采样得到的闪烁室相对固有误差≤5%, 达到了《地震水文地球化学观测技术规范》的要求, 而负压采样方式得到的闪烁室相对固有误差>5%, 未达到《地震水文地球化学观测技术规范》的要求; 因此, 循环采样方式更适合地震监测闪烁室法测氡仪的氡室校准。 相似文献
4.
B. Scott Stephens Anita P. Kapernick Jochen F. Mueller 《Marine pollution bulletin》2009,58(8):1116-1122
Subsequent to an initial wet season flood event in the Brisbane River, Australia, both fast (naked disk) and slow (membrane-covered) variants of SDB-RPS Empore disk passive sampling devices were deployed with an automated grab sampling program. A trend increase in the aquatic dissolved concentrations of diuron and simazine was observed over a 10-day period. Kinetic and equilibrium parameters for each sampler were calculated based on the dynamic concentration. Absolute percent difference for duplicate passive samples was <10% in the fast and <25% in the slow samplers. For kinetic sampling, significantly shortened integrative periods are available with the fast compared with the slow variant, with higher sampling rates offering improved detection limits. The study demonstrates a method for determining kinetic parameters of passive samplers in a variable concentration field deployment, and illustrates the differences in quality between active and passive data, in terms of capturing changes in concentration associated with rainfall events. 相似文献
5.
非规则采样快速傅里叶变换（NFFT）主要用于快速计算非规则采样数据的频谱及重建.该方法为非规则采样数据频谱重建技术的核心算法.在实现NFFT算法时,高速度和高精度计算是其应用的前提和关键.本文针对二维NFFT计算效率,应用表驱动思路进行改进,将Gauss褶积算子由矩形改进为椭圆以减少计算量,将e指数计算改进为乘法以加快计算速度,并建表解决NFFT算法在地震资料处理中的应用问题.本文同时给出了非规则采样地震数据NFFT谱重建方法.最后本文给出算例验证提出方法的计算速度和精度,和非规则采样地震资料重建结果. 相似文献
6.
Optimal decision-making model of spatial sampling for survey of China’s land with remotely sensed data 总被引：2，自引：0，他引：2
In the remote sensing survey of the country land, cost and accuracy are a pair of conflicts, for which spatial sampling is
a preferable solution with the aim of an optimal balance between economic input and accuracy of results, or in other words,
acquirement of higher accuracy at less cost. Counter to drawbacks of previous application models, e.g. lack of comprehensive
and quantitativecomparison, the optimal decision-making model of spatial sampling is proposed. This model first acquires the
possible accuracy-cost diagrams of multiple schemes through initial spatial exploration, then regresses them and standardizes
them into a unified reference frame, and finally produces the relatively optimal sampling scheme by using the discrete decision-making
function (built by this paper) and comparing them in combination with the diagrams. According to the test result in the survey
of the arable land using remotely sensed data, the Sandwich model, while applied in the survey of the thin-feature and cultivated
land areas with aerial photos, can better realize the goal of the best balance between investment and accuracy. With this
case and other cases, it is shown that the optimal decision-making model of spatial sampling is a good choice in the survey
of the farm areas using remote sensing, with its distinguished benefit of higher precision at less cost or vice versa. In order to extensively apply the model in the surveys of natural resources, including arable farm areas, this paper proposes
the prototype of development using the component technology, that could considerably improve the analysis efficiency by insetting
program components within the software environment of GIS and RS. 相似文献
7.
Photosystem II (PSII) herbicides have been shown to affect the photosynthesis of corals at low, environmentally relevant concentrations. The recent detection of the PSII herbicide Irgarol-1051 in coastal waters of Hong Kong at concentrations above the EC(50) for reduction of photosynthesis of corals prompted further investigation into the extent of PSII herbicide pollution in coral reefs of Hong Kong. Snap-shot and passive samples were taken from coral reef sites and evaluated via HPLC/MS-MS and a novel bioanalytical technique. Low concentrations (less than 10 ng L(-1)) of diuron and atrazine were found at all study sites. Extracts from these samples concentrated by a factor of 10 were found to reduce the photosynthetic yield of zooxanthellae. It appears unlikely that herbicide pollution is a key issue in isolation but may act synergistically with other stressors to reduce the viability of Hong Kong's coral reefs. The study has also demonstrated the feasibility of combining sample extraction techniques with a coral specific bioanalytical technique for a sensitive assessment of risks associated with herbicide exposure in corals. 相似文献
8.
主要从Miniseed格式以及Steim算法的相关原理出发,分析单台1 s理论最大和最小数据量。根据福建台网数据,对各种仪器取样,然后取平均,得出实际每个包数据量的一般值和最大值。根据现有数据传输方式,除去传输中的理论损耗,计算相关带宽对应的最大数据传输量。在得出地震数据单台1 s数据临界值和带宽最大传输量的情况下,总结计算结果,得出测震传输网络传输带宽临界值。 相似文献
9.
Optimal decision-making model of spatial sampling for survey of China’s land with remotely sensed data 总被引：1，自引：0，他引：1
LI Lianfa WANG Jinfeng & LIU Jiyuan . Institute of Geographic Sciences & Natural Resources Research Chinese Academy of Sciences Beijing China . Department of Intelligence Science Peking University Beijing China Correspondence should be addressed to Li Lianfa 《中国科学D辑(英文版)》2005,(6)
For a long term,in the survey of the country land areas,how to balance the conflicts between survey cost and result accuracy,or in other words,how to acquire the highest accuracy within the capital limit or vice verse,is a major problem that couldn’t have well been solved[1].Spatial sampling,aiming this,is the preferable option and the important and the first stepin the survey of geo-analysis,including the survey of the country land resource as well in that whether the sampling scheme is good … 相似文献
10.
Colloidal materials and macromolecules that are less than 0.45 mircons in diameter can act to transport both hydrophobic and hydrophilic contaminations in subsurface waters. An automated hollow-fibre ultrafiltration apparatus is described and evaluated regarding its ability to physically size and isolate colloidal materials from natural waters. Sufficient size-fractionated colloidal samples can be obtained from 60 litre samples to perform inorganic, organic, and radionuclide characterizations, as well as allow the binding capacities of humic and fulvic materials to be evaluated. Samples processed in the field with the automated system were compared with laboratory analyses using single cartridge hollow-fibre ultrafilters and found to agree well with each other. Typical sample reproducibilities were with 15 per cent. The results indicate that field collection of colloidal materials is feasible with minimal sample perturbation using the automated sampler. 相似文献
11.
S. X. Wang Vijay P. Singh 《Stochastic Environmental Research and Risk Assessment (SERRA)》1994,8(3):233-258
The sampling variance of a T-year flood when estimated using a curve-fitting method results from the errors in hydrologic observations, plotting positions, and model-fitting. This paper develops a method to quantify the contribution of plotting positions to the sampling variance of the T-year flood magnitude. Application of the method to 150 flood-flow data sets of 41 rivers in the People's Republic of China show that the errors due to plotting positions contribute more to the sampling variance than others. 相似文献
12.
A wide variety of sampling programmes may now be considered practical with the recent developments in data logger and water sampler technology. In ephemeral systems the water sampler remains idle for long periods between events. Two approaches are described which overcome the problems of sampling in ephemeral systems: short interval time dependent sampling (TDS) and automated flow proportional sampling (FPS). Both approaches utilize the data logger's ability to perform intermediate operations on incoming data to control the initiation of water sampling. The logger programs are described and allow many recorder/water sampler units to be controlled from one device. The relative merits of the two approaches are discussed in terms of experimental requirements and data precision. 相似文献
13.
《Marine pollution bulletin》2014,78(1-2):63-68
Numerous species of seabirds have been shown to ingest anthropogenic debris, but few studies have compared ingestion rates between adults and juveniles of the same species. We investigated marine debris ingestion by short-tailed shearwaters (Puffinus tenuirostris) obtained through two stranding events on North Stradbroke Island, Australia in 2010 (n = 102; adult) and 2012 (n = 27; juveniles). Necropsies were conducted and solid contents found in guts were categorized into type and color. Over 67% of birds ingested anthropogenic debris: 399 pieces of debris were identified. We found no significant relationship between body condition of birds which had ingested anthropogenic debris and those that had not. Juvenile birds were more likely to ingest debris than were adult birds and juveniles ingested significantly more pieces of debris than did adults. Male and female birds ingested similar amounts and weights of debris. To determine if P. tenuirostris actively selects for certain types of debris, we compared ingested debris to samples obtained from boat-based tows. Significant differences were found, suggesting that the birds select for hard plastic, rubber and balloons. 相似文献
14.
With the aim of finding an efficient, standardised and practical protocol for sorting macroinvertebrate samples for water management practice, three different sorting techniques were tested: RIVPACS sorting, a modified AQEM/STAR (MAS) sorting protocol and a Live-sorting method. Based on the same AQEM/STAR sample to ensure comparable results, we compared RIVPACS and MAS sorting for 20 samples, and Live-sorting and MAS for a different set of 20 samples. Comparisons were based on both ecological and financial parameters relevant for the implementation of the EU Water Framework Directive in Germany. Parameters include recently developed multimetric assessment indices, their stream type specific core metric results, time effort and costs. While RIVPACS and MAS sorting produced similar results in terms of ecological assessment, time effort and costs, Live-sorting differed notably in all three respects. Live-sorting is the quickest and least expensive protocol, but shows higher variability than the other protocols. We discuss the differences and the level of standardisation for each of these methods. 相似文献
15.
I. Braud Ch. Obled A. Phamdinhtuan 《Stochastic Environmental Research and Risk Assessment (SERRA)》1993,7(2):146-160
Empirical Orthogonal Function (EOF) analysis of spatial random fields involves calculation of the eigenfunctions of the covariance kernel of the field. For real-world applications, a numerical approximation is necessary because the process is spatially discretized. An approximation for two-dimensional fields is proposed and then, analytical solutions of the integral problem are derived and used to study the accuracy of the numerical approximations. Sampling effects are also considered. 相似文献
16.
In order to study the relationship between water composition and stream flow rate, it is desirable to sample at a frequency related to flow rate, especially during storm events. In a rural catchment of 18 ha near Oxford, the rate of rainfall was found to be linearly related to discharge on the rising limb of the stream hydrograph. A sampling system was therefore designed in which electrical pulses from a tipping-bucket raingauge were used to initiate and control the action of an automatic water sampler. A threshold rainfall intensity is set above which sampling commences. Sampling then continues at regular increments of rainfall until the intensity drops below the threshold, after which sampling occurs at regular intervals during the period that the stream flow reverts to normal. The CMOS electrical circuits which control the sampling also operate a cassette tape recorder which records the time of each tip of the raingauge and operation of the sampler. Since the sytem is designed to impose very little additional load on the battery which powers the water sampler, and can operate unattended for at least a fortnight, it is ideal for use in small, remote catchments. The system has been extended to include measurements of water temperature and could provide other measurements as well. 相似文献
17.
高密度空间采样地震数据特点分析 总被引：3，自引：0，他引：3
中国陆相沉积盆地的地质结构复杂,储层岩性的多变,需要有高精度的勘探方法。高密度空间采样是提高地震勘探精度的一项新技术。本文简要说明了点激发和点接收技术,分析高密度空间采样的野外工作方法,介绍了Gijs j．o．Vermeer提出的对称采样原理,从波场连续性的角度探讨了高密度空间采样技术。重点分析高密度空间采样数据的特点, 即:高密集的初至波有利于近地表结构的调查,可提高静校正的精度;小偏移距、小点距接收增加了浅层的有效覆盖次数,提高浅层反射的成像精度; 对规则噪声可实现无假频采样,室内的噪声分析和噪声压制的精度随着提高;高密度采集使波场连续性增强,使得各种数学变换的精度提高,有利于不同波场的分离。最后指出高密度空间采样地震勘探技术的难点在于室内数据处理,针对海量数据的分析和处理方法还需要进行深入细致的研究工作。 相似文献
18.
用生物模拟采样技术模拟研究不同取代氯酚在金鱼(Crassius auratus)体内的富集和降解 总被引：1，自引：0，他引：1
在实验室控制条件的流动体系中，研究了九种典型氯酚类化合物在半渗透膜生物模拟采样器件（SPMD）和金鱼体内的富集动力学过程。基于氯酚污染物在SPMD中的生物浓缩和在鱼体脂肪中生物富集的差别，研究了氯酚污染物在生物体内的降解性和降解作用的结构／效应关系。结果表明氯酚类污染物在SPMD中的浓缩作用和在鱼体中的富集作用非常相似。氯酚化合物的生物降解性随氯取代基数量增加而降低，并与氯取代基的位置有关。 相似文献
19.
20.
Johana Brokešová 《Pure and Applied Geophysics》1996,148(3-4):503-538
The seismic wave field, in its high-frequency asymptotic approximation, can be interpolated from a low- to a high-resolution spatial grid of receivers and, possibly, point sources by interpolating the eikonal (travel time) and the amplitude. These quantities can be considered as functions of position only. The travel time and the amplitude are assumed to vary in space only slowly, otherwise the validity conditions of the theory behind would be violated. Relatively coarse spatial sampling is then usually sufficient to obtain their reasonable interpolation. The interpolation is performed in 2-D models of different complexity. The interpolation geometry is either 1-D, 2-D, or 3-D according to the source-receiver distribution. Several interpolation methods are applied: the Fourier interpolation based on the sampling theorem, the linear interpolation, and the interpolation by means of the paraxial approximation. These techniques, based on completely different concepts, are tested by comparing their results with a reference ray-theory solution computed for gathers and grids with fine sampling. The paraxial method holds up as the most efficient and accurate in evaluating travel times from all investigated techniques. However, it is not suitable for approximation of amplitudes, for which the linear interpolation has proved to be universal and accurate enough to provide results acceptable for many seismological applications. 相似文献