Prediction of Salmonella in seawater by total and faecal coliforms and Enterococci     

Maria A. Efstratiou  Athena Mavridou 《Marine pollution bulletin》2009,58(2):201-205

The power of total coliforms (TC), faecal coliforms (FC) and Enterococci to predict the presence of Salmonella in seawater was investigated. Indicator cut-off values with the most satisfactory combination of sensitivity and specificity in predicting Salmonella presence were 1000 CFU 100 ml⁻¹ TC, 200 CFU 100 ml⁻¹ FC, 500 CFU 100 ml⁻¹ Enterococci. When TC or FC were used for Salmonella prediction in logistic regression, then the addition of another indicator did not have a statistically significant effect. When Enterococci were used for prediction, then the addition of either of the two other indicators led to a statistically significant improvement (P = 0.001 for TC, P = 0.003 for FC). These results suggest that using either TC or FC alone provided an adequate indicator of Salmonella presence, but a statistically significant improvement is possible over using Enterococci alone. Concerning Enterococci, European Union limits for excellent coastal water quality (100 CFU 100 ml⁻¹) and United States Environmental Protection Agency criteria for marine bathing waters (35 CFU 100 ml⁻¹) have the same value in predicting Salmonella absence (92.5%).  相似文献   

Impact of erosion and accretion on the distribution of enterococci in beach sands     

Gast RJ  Gorrell L  Raubenheimer B  Elgar S 《Continental Shelf Research》2011,31(14):1457-1461

Bacterial pathogens in coastal sediments may pose a health risk to users of beaches. Although recent work shows that beach sands harbor both indicator bacteria and potential pathogens, it is neither known how deep within beach sands the organisms may persist nor if they may be exposed during natural physical processes. In this study, sand cores of approximately 100 cm depth were collected at three sites across the beach face in Kitty Hawk, North Carolina, before, during, and after large waves from an offshore hurricane. The presence of DNA from the fecal indicator bacterium Enterococci was detected in subsamples at different depths within the cores by PCR amplification. Erosion and accretion of beach sand at the three sites were also determined for each sampling day. The results indicate that ocean beach sands with persisting enterococci signals could be exposed and redistributed when wind, waves, and currents cause beach erosion or accretion.  相似文献   

国土资源科技管理统计指标体系的设计     

杨  玲等 《国土资源情报》2014,(2):53-56,45

科技统计指标体系是对科技活动进行统计的重要工具。本文从国土资源科技管理的角度对科技统计指标体系进行分析和补充,细化了科技投入与研发、科技人才培养、科技产出、国际科技合作的量化值,进一步丰富和完善了科技统计的指标体系。  相似文献   

A comparison of rainfall estimation techniques for sub-Saharan Africa     

Elias Symeonakis  Rogerio Bonifaçio  Nick Drake 《International Journal of Applied Earth Observation and Geoinformation》2009

Interpolated rain-gauge data were compared to Meteosat-based precipitation estimates for sub-Saharan Africa. Validation was carried out using a dataset from a very dense gauge network in South Africa, on a point-to-pixel (PO–PI) as well as on a pixel-to-pixel (PI–PI) basis. Error criteria computed at the gauged pixels indicate that overall the interpolated estimates perform similarly to the satellite-based data: they provide good estimates of lower but underestimate larger precipitation amounts. It is concluded that the satellite estimates are more fitted for the operational modelling of processes such as surface runoff and soil erosion, especially in the developing areas where resources are scarce.  相似文献   

基于WiFi与GPS组合定位算法的无缝定位方法研究     

马燕  袁蔚林  陈秀万  许玉斌  孙华波 《地理与地理信息科学》2013,29(3)

无线局域网络(WLAN)是一种全新的无线信号传输平台,该文在总结目前无缝定位与导航技术的研究现状、分析存在的问题和发展趋势的基础上,提出了联合GPS和无线局域网络的组合定位方法,以实现室内外的无缝定位与导航.同时,在深入研究卫星导航定位和无线传感器网络定位原理与算法基础上,针对定位环境的不同,提出了无缝定位的解决方案、转换机制和切换策略,并以WiFi网与GPS组合定位算法为例,进行了详细分析和深入讨论,所用算法可以实现无GPS、少于4颗可用卫星以及GDOP值不满足定位情况下的定位,与单独WiFi网络定位算法相比,该算法可以提高定位精度.  相似文献   

东海黑潮区莹虾类的初步研究     

马兆党  宋庆云 《海洋科学进展》1992,(4)

1984年6月和1985年12月,对东海进行了首次黑潮实验性调查.整个调查区涉及到东海及东海黑潮区。作为综合调查项目其中之一的生物调查,在全调查区进行了取样:冬、夏两航次共采集浮游动物样品115份,经分析共鉴定出莹虾类4种。夏季(6月)出现中型莹虾 Luciferintermedius、正型莹虾 Lucifer typus、刷状莹虾 Lnckfer penicillifer、东方莹虾 Lucifer oriental-is;冬季(12月)出现中型莹虾 Lucifer intermedius、正型莹虾 Lucifer typus,可以明显地看出莹虾类的数量分布和种类分布与水温、营养盐、水团、流系等之间有密切的关系。并且莹虾类的数量分布与渔场的位置也有一定关系。据本次调查及资料分析,夏季可将中型莹虾作为东海混合水的指标种;正型莹虾可作为黑潮水的指标种;刷状莹虾可作为台湾暖流的指标种,为水文的调查提供较有价值的参考.  相似文献   

A counter-intuitive result for mixture random fields     

Andrew R. Solow 《Mathematical Geology》1989,21(3):379-382

  相似文献   

Properties and limitations of sequential indicator simulation   总被引：2，自引：0，他引：2  

X.?EmeryEmail author 《Stochastic Environmental Research and Risk Assessment (SERRA)》2004,18(6):414-424

The sequential indicator algorithm is a widespread geostatistical simulation technique that relies on indicator (co)kriging and is applicable to a wide range of datasets. However, such algorithm comes up against several limitations that are often misunderstood. This work aims at highlighting these limitations, by examining what are the conditions for the realizations to reproduce the input parameters (indicator means and correlograms) and what happens with the other parameters (other two-point or multiple-point statistics). Several types of random functions are contemplated, namely: the mosaic model, random sets, models defined by multiple indicators and isofactorial models. In each case, the conditions for the sequential algorithm to honor the model parameters are sought after. Concurrently, the properties of the multivariate distributions are identified and some conceptual impediments are emphasized. In particular, the prior multiple-point statistics are shown to depend on external factors such as the total number of simulated nodes and the number and locations of the samples. As a consequence, common applications such as a flow simulation or a change of support on the realizations may lead to hazardous interpretations.  相似文献   

Metal contaminants for modelling lobster (Homarus americanus) migration patterns in the Inner Bay of Fundy, Atlantic Canada     

Chou CL  Paon LA  Moffatt JD 《Marine pollution bulletin》2002,44(2):134-141

A method, which uses metal compositions in lobster digestive glands as natural environmental tags, has been developed to trace lobster movements. Lobsters were collected from three selected sites, Minas Channel, Minas Basin, and Cobequid Bay, Inner Bay of Fundy, New Brunswick, Canada, that were known to be contaminated with Cu. Five metal variables (Ag, Cd, Cu, Mn and Zn) were processed for principal component analysis (PCA). Metal concentration and burden models were investigated and PCA was able to differentiate lobsters from the respective catch sites. The method was applied to investigate the May and June lobsters collected at the three sites to determine the migration rate during this period of the fishing season. The results show a high level of mixing at Minas Basin and Cobequid Bay in June, and lobster movement inward toward the inner reaches of the bay, with very limited movement outward from the inner bay.  相似文献   

Risk assessment of water erosion for the Qareh Aghaj subbasin, southern Iran     

Masoud Masoudi  A. M. Patwardhan  S. D. Gore 《Stochastic Environmental Research and Risk Assessment (SERRA)》2006,21(1):15-24

South of the Zagros belt, the entire land of Southern Iran faces problems arising out of various types of land degradation of which water erosion forms a major type. A new model has been developed for assessing the risk of water erosion. Taking into consideration nine indicators of water erosion the model identifies areas with ‘Potential Risk’ (risky zones) and areas of ‘Actual Risk’ as well as projects the probability of the worse degradation in future. The Qareh Aghaj subbasin (1,265,000 ha), which covers the upper reaches of Mond River, has been chosen for a test risk assessment of this kind. The preparation of risk maps based on the GIS analysis of these indicators will be helpful for prioritizing the areas to initiate remedial measures. The different kinds of data for indicators of water erosion were gathered from the records and published reports of the governmental offices of Iran. By fixing the thresholds of severity classes of the nine indicators a hazard map for each indicator was first prepared in GIS. The risk classes were defined on the basis of risk scores arrived at by assigning the appropriate attributes to the indicators and the risk map was prepared by overlaying nine hazard maps in the GIS. Areas under potential risk have been found to be widespread (63%) in the basin and when classified into subclasses with different probability levels the model projects a statistical picture of the risk of land degradation.  相似文献