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1.
Delmore JE Snyder DC Tranter T Mann NR 《Journal of environmental radioactivity》2011,102(11):1008-1011
There are multiple paths by which radioactive cesium can reach the effluent from reactor operations. The radioactive 135Cs/137Cs ratios are controlled by these paths. In an effort to better understand the origin of this radiation, these 135Cs/137Cs ratios in effluents from three power reactor sites have been measured in offsite samples. These ratios are different from global fallout by up to six fold and as such cannot have a significant component from this source. A cesium ratio for a sample collected outside of the plant boundary provides integration over the operating life of the reactor. A sample collected inside the plant at any given time can be much different from this lifetime ratio. The measured cesium ratios vary significantly for the three reactors and indicate that the multiple paths have widely varying levels of contributions. There are too many ways these isotopes can fractionate to be useful for quantitative evaluations of operating parameters in an offsite sample, although it may be possible to obtain limited qualitative information for an onsite sample. 相似文献
2.
The ability to detect and to develop a precise and accurate estimate of the entrainment mortality fraction is an important step in projecting power plant impacts on future fish population levels. Recent work indicates that these mortailities may be considerably less than 100% for some fish species in the early life stages. Point estimates of the entrainment mortality fraction have been developed based on probabilistic arguments, but the precision of these estimates has not been studied beyond the simple statistical test of the null hypothesis that no entrainment mortaility exists.The ability to detect entrainment mortality is explored as a function of the sample sizes (numbers of organisms collected) at the intake and discharge sampling stations of a power plant and of the proportion of organisms found alive in the intake samples (intake survival). Minimum detectable entrainment mortality, confidence interval width, and type II error (probability of accepting the null hypothesis of no entrainment mortality when there is mortality) are considered. Increasing sample size and/or decreasing sampling mortality will decrease the minimum detectable entrainment mortality, confidence interval width, and type II error for a given level of type I error.The results of this study are considered in the context of designing useful monitoring programs for determining the entrainment mortality fraction. Preliminary estimates of intake survival and the entrainment mortality fraction can be used to obtain estimates of the sample size needed for a specified level of confidence interval width or type II error. Final estimates of the intake survival and the entrainment mortality fraction can be used to determine the minimum detectable entrainment mortality and the type II error. 相似文献
3.
4.
Brian E. Reichert Mylea Bayless Tina L. Cheng Jeremy T. H. Coleman Charles M. Francis Winifred F. Frick Benjamin S. Gotthold Kathryn M. Irvine Cori Lausen Han Li Susan C. Loeb Jonathan D. Reichard Thomas J. Rodhouse Jordi L. Segers Jeremy L. Siemers Wayne E. Thogmartin Theodore J. Weller 《Ambio》2021,50(4):901
Collaborative monitoring over broad scales and levels of ecological organization can inform conservation efforts necessary to address the contemporary biodiversity crisis. An important challenge to collaborative monitoring is motivating local engagement with enough buy-in from stakeholders while providing adequate top-down direction for scientific rigor, quality control, and coordination. Collaborative monitoring must reconcile this inherent tension between top-down control and bottom-up engagement. Highly mobile and cryptic taxa, such as bats, present a particularly acute challenge. Given their scale of movement, complex life histories, and rapidly expanding threats, understanding population trends of bats requires coordinated broad-scale collaborative monitoring. The North American Bat Monitoring Program (NABat) reconciles top-down, bottom-up tension with a hierarchical master sample survey design, integrated data analysis, dynamic data curation, regional monitoring hubs, and knowledge delivery through web-based infrastructure. NABat supports collaborative monitoring across spatial and organizational scales and the full annual lifecycle of bats. 相似文献
5.
Halse SA Scanlon MD Cocking JS Smith MJ Kay WR 《Environmental monitoring and assessment》2007,134(1-3):161-175
AusRivAS is an Australia-wide program that measures river condition using predictive models to compare the macroinvertebrate families occurring at a river site with those expected if the site were in natural condition. Results of assessment of 685 sites across all major rivers in Western Australia are presented. Most rivers were in relatively natural condition in the northern half of the state where the human population is low and pastoralism is the major land use. In the south, where the human population is higher and agriculture is more intensive, rivers were mostly more disturbed. AusRivAS assessment produced some erroneous results in rivers of the south-west cropping zone because of the lack of appropriate reference site groups and biased distribution of sampling sites. Collecting low numbers of animals from many forested streams, because of low stream productivity and samples that were difficult to sort, also affected assessments. Overall, however, AusRivAs assessment identified catchment processes that were inimical to river health. These processes included salinisation, high nutrient and organic loads, erosion and loss of riparian vegetation. River regulation, channel modification and fire were also associated with river degradation. As is the case with other assessment methods, one-off sampling at individual sites using AusRivAS may be misleading. Seasonal drought, in particular, may make it difficult to relate conditions at the time of sampling to longer-term river health. AusRivAS has shown river condition in Western Australia is not markedly different from other parts of Australia which, as a whole, lacks the substantial segments of severely degraded river systems reported in England. 相似文献
6.
Budziak D Richard L Beltrame E Carasek E 《Environmental monitoring and assessment》2007,127(1-3):435-444
Formation of trihalomethanes (THM) was monitored at the Laboratório de Camarões Marinhos (LCM) from the Universidade Federal de Santa Catarina. THM could be present because chlorinated effluents from disinfection are discharged from the different hatchery rooms. THM quantification was done through an analytical methodology using Purge&;Trap coupled with a gas chromatograph equipped with an electron capture detector. Relative standard deviation (RSD), limit of detection (LOD) and limit of quantification (LOQ) for the methodology corresponded to the ranges of 8–17%; 0.01–0.03 μg L?1 and 0.03–0.08 μg L?1, respectively. Linear working range was of 0.1–8.0 μg L?1 for all compounds. Enrichment and recovery method was applied to evaluate possible matrix effects and the results varied from 71.2% to 107.9%. LCM was monitored between August and December, 2004. This study showed that THM did not increase with the increase in postlarvae production and also that the aquatic life and the surrounding environment were not affected. 相似文献
7.
Cost-efficient sample designs for collection of ground data and accurate mapping of variables are required to monitor natural
resources and environmental and ecological systems. In this study, a sample design and mapping method was developed by integrating
stratification, model updating, and cokriging with Landsat Thematic Mapper (TM) imagery. This method is based on the spatial
autocorrelation of variables and the spatial cross-correlation among them. It can lead to sample designs with variable grid
spacing, where sampling distances between plots vary depending on spatial variability of the variables from location to location.
This has potential cost-efficiencies in terms of sample design and mapping. This method is also applicable for mapping in
the case in which no ground data can be collected in some parts of a study area because of the high cost. The method was validated
in a case study in which a ground and vegetation cover factor was sampled and mapped for monitoring soil erosion. The results
showed that when the sample obtained with three strata using the developed method was used for sampling and mapping the cover
factor, the sampling cost was greatly decreased, although the error of the map was slightly increased compared to that without
stratification; that is, the sample cost-efficiency quantified by the product of cost and error was greatly increased. The
increase of cost-efficiency was more obvious when the cover factor values of the plots within the no-significant-change stratum
were updated by a model developed using the previous observations instead of remeasuring them in the field. 相似文献
8.
Stafford JD Reinecke KJ Kaminski RM Gerard PD 《Journal of environmental management》2006,78(4):353-361
Large-scale sample surveys to estimate abundance and distribution of organisms and their habitats are increasingly important in ecological studies. Multi-stage sampling (MSS) is especially suited to large-scale surveys because of the natural clustering of resources. To illustrate an application, we: (1) designed a stratified MSS to estimate late autumn abundance (kg/ha) of rice seeds in harvested fields as food for waterfowl wintering in the Mississippi Alluvial Valley (MAV); (2) investigated options for improving the MSS design; and (3) compared statistical and cost efficiency of MSS to simulated simple random sampling (SRS). During 2000-2002, we sampled 25-35 landowners per year, 1 or 2 fields per landowner per year, and measured seed mass in 10 soil cores collected within each field. Analysis of variance components and costs for each stage of the survey design indicated that collecting 10 soil cores per field was near the optimum of 11-15, whereas sampling >1 field per landowner provided few benefits because data from fields within landowners were highly correlated. Coefficients of variation (CV) of annual estimates of rice abundance ranged from 0.23 to 0.31 and were limited by variation among landowners and the number of landowners sampled. Design effects representing the statistical efficiency of MSS relative to SRS ranged from 3.2 to 9.0, and simulations indicated SRS would cost, on average, 1.4 times more than MSS because clustering of sample units in MSS decreased travel costs. We recommend MSS as a potential sampling strategy for large-scale natural resource surveys and specifically for future surveys of the availability of rice as food for waterfowl in the MAV and similar areas. 相似文献
9.
The regional-scale importance of an aquatic stressor depends both on its regional extent (i.e., how widespread it is) and
on the severity of its effects in ecosystems where it is found. Sample surveys, such as those developed by the U.S. Environmental
Protection Agency’s Environmental Monitoring and Assessment Program (EMAP), are designed to estimate and compare the extents,
throughout a large region, of elevated conditions for various aquatic stressors. In this article, we propose relative risk
as a complementary measure of the severity of each stressor’s effect on a response variable that characterizes aquatic ecological
condition. Specifically, relative risk measures the strength of association between stressor and response variables that can
be classified as either “good” (i.e., reference) or “poor” (i.e., different from reference). We present formulae for estimating
relative risk and its confidence interval, adapted for the unequal sample inclusion probabilities employed in EMAP surveys.
For a recent EMAP survey of streams in five Mid-Atlantic states, we estimated the relative extents of eight stressors as well
as their relative risks to aquatic macroinvertebrate assemblages, with assemblage condition measured by an index of biotic
integrity (IBI). For example, a measure of excess sedimentation had a relative risk of 1.60 for macroinvertebrate IBI, with
the meaning that poor IBI conditions were 1.6 times more likely to be found in streams having poor conditions of sedimentation
than in streams having good sedimentation conditions. We show how stressor extent and relative risk estimates, viewed together,
offer a compact and comprehensive assessment of the relative importances of multiple stressors. 相似文献
10.
分光光度法测定水样中铬 总被引:3,自引:0,他引:3
在pH4.4HAC-NaAc缓冲介质及乳化剂OP存在下,Cr6+与二溴羟基苯基荧光酮(DBHPF)显色反应生成桔红色络合物.该络合物最大吸收位于482nm波长处,表现摩尔吸光系数εmax=3.47×104.络合物配位比为Cr6+:DBHPF=2:3,Cr6+在0-16μg/25mL范围内遵守比耳定律.方法已用于水样中微量铬的测定,结果满意. 相似文献