Modeling of non-point source pollution in a Mediterranean drainage basin

SWAT ver. 2000 was used to predict hydrographs, and sediment, nitrate and total phosphorus loadings from a 1349 km² mountainous/agricultural watershed in Northern Greece. The model was calibrated and verified using continuous meteorological data from eight stations within the drainage area, and runoff, sediment and nutrient concentrations measured at nine stations located within the main tributaries of the watershed, for the time period from May 1st, 1998 to January 31st, 2000. Model validation methodology and resulting input parameters appropriate for Mediterranean drainage basins are presented. Predicted by the model hydrographs, sedimentographs and pollutographs are plotted against observed values and show good agreement. Model performance is evaluated using the root mean square error computation and scattergrams of predicted versus observed data. The validated model is also used to test the effectiveness of three alternative cropping scenarios in reducing nutrient loadings from the agricultural part of the watershed. The study showed that this model, if properly validated, can be used effectively in testing management scenarios in Mediterranean drainage basins.     

Estimating Trophic State Proportions of a Regional Lake Population: Are Larger Samples Always Better?

During the summers of 1991–1994, the Environmental Monitoringand Assessment Program (EMAP) sampled 344 lakes throughout thenortheastern United States using a proportional stratified sampling design based on lake size. Approximately one-quarter ofthe 344 lakes were sampled each year (4 years) for totalphosphorus to determine the proportion (and associated95% confidence intervals) of the northeast lake population 1ha (11,076 ± 1,699 lakes) that was in oligotrophic,mesotrophic, eutrophic, or heupereutropic (4 classes) conditionaccording to the total phosphorus criteria of the North AmericaLake Manegement Society. Estimates for the second, third, andfourth yr were developed as cumulative of the previous yrsamples and the current yr samples for the northeast as a wholeand for each of its three ecoregions (4 regions). New confidence intervals were computed for each cumulative yrcondition estimate. This produced a total (4 years × 4classes × 4 regions) of 64 cumulative yr tropic conditionestimates. Confidence intervals for 21% of these estimates didnot shorten with increased sample size. This phenomena raisedquestions about the accuracy of estimates based on cumulativesampling procedures. We explain why and how the phenomenon comesabout with both straight random and proportional randomsampling. Further, we present an example of the effects thisphenomenon has on lake tropic state condition estimates in thenortheastern United States.     

Geological CO2 Storage as a Climate Change Mitigation Option

Carbon dioxide (CO₂₎ capture and storage is increasingly being considered as an important climate change mitigation option. This paper explores provisions for including geological CO₂ storage in climate policy. The storage capacity of Norway's Continental Shelf is alone sufficient to store a large share of European CO₂ emissions for many decades. If CO₂ is injected into oil reservoirs there is an additional benefit in terms of enhanced oil recovery. However, there are significant technical and economic challenges, including the large investment in infrastructure required, with related economies of scale properties. Thus CO₂ capture, transportation and storage projects are likely to be more economically attractive if developed on a large scale, which could mean involving two or more nations. An additional challenge is the risk of future leakages from storage sites, where the government must take on a major responsibility. In institutional and policy terms, important challenges are the unsettled status of geological CO₂ storage as a policy measure in the Kyoto Protocol, lack of relevant reporting and verification procedures, and lack of decisions on how the option should be linked to the flexibility mechanisms under the Kyoto Protocol. In terms of competitiveness with expected prices for CO₂ permits under Kyoto Protocol trading, the relatively high costs per tonne of CO₂ stored means that geological CO₂ storage is primarily of interest where enhanced oil recovery is possible. These shortcomings and uncertainties mean that companies and governments today only have weak incentives to venture into geological CO₂ storage.     

张道口-1井水位观测精度变化分析研究

本文对张道口-1井模拟水位、数字化水位观测精度进行了对比，进一步分析了影响数字化水位观测精度的几个因素，提出了数字化水位在日常观测中应注意的几个问题。     

钼锑抗分光光度法测定总磷的精密度偏性试验分析

通过钼锑抗分光光度法测定总磷的精密度偏性试验及其结果分析,提出本标准方法用光程10mm比色皿比色测定时,由于测定的灵敏度较低,使总磷低浓度测定的精密度和准确度难于达到标准方法要求;建议钼锑抗分光光度法测定总磷时,最好选用30mm比色皿比色测定.     

催化CODcr快速测法的精密度与准确度实验

化学需氧量标准分析方法测定时间长、操作繁琐。本实验采用CTL—BX3C型便携式COD快速测定仪能在20分钟获得COD数据，同时耗能低、省时省力、减少污染。催化CODcr快速法的精密度与准确度均能达到要求。     

提高洪水智能预报中洪峰预报精度方法的研究

针对防洪减灾的实际需要,对如何提高智能网络对洪峰的预报精度问题进行了深入系统的研究,提出了峰值放大修正系数和遗传算法优化网络初始权重相结合的改进算法,历史资料的检验结果表明了这些改进策略的有效性和可靠性.     

Toward accurate and precise estimates of lion density

Reliable estimates of animal density are fundamental to understanding ecological processes and population dynamics. Furthermore, their accuracy is vital to conservation because wildlife authorities rely on estimates to make decisions. However, it is notoriously difficult to accurately estimate density for wide‐ranging carnivores that occur at low densities. In recent years, significant progress has been made in density estimation of Asian carnivores, but the methods have not been widely adapted to African carnivores, such as lions (Panthera leo). Although abundance indices for lions may produce poor inferences, they continue to be used to estimate density and inform management and policy. We used sighting data from a 3‐month survey and adapted a Bayesian spatially explicit capture‐recapture (SECR) model to estimate spatial lion density in the Maasai Mara National Reserve and surrounding conservancies in Kenya. Our unstructured spatial capture‐recapture sampling design incorporated search effort to explicitly estimate detection probability and density on a fine spatial scale, making our approach robust in the context of varying detection probabilities. Overall posterior mean lion density was estimated to be 17.08 (posterior SD 1.310) lions >1 year old/100 km², and the sex ratio was estimated at 2.2 females to 1 male. Our modeling framework and narrow posterior SD demonstrate that SECR methods can produce statistically rigorous and precise estimates of population parameters, and we argue that they should be favored over less reliable abundance indices. Furthermore, our approach is flexible enough to incorporate different data types, which enables robust population estimates over relatively short survey periods in a variety of systems. Trend analyses are essential to guide conservation decisions but are frequently based on surveys of differing reliability. We therefore call for a unified framework to assess lion numbers in key populations to improve management and policy decisions.     

某型机车牵引电机传动端轴承低速轻载无飞溅润滑试验研究

主要根据客户要求,在低速(1 km/h)及轻载工况下,测量传动端轴承无飞溅润滑条件下的温升等参数,而进行相关的电机试验,为某型机车牵引电机传动端轴承在低速及轻载工况下,无飞溅润滑提供试验验证及技术支撑。     

浅谈环境监测实验室仪器设备的期间核查

实验室仪器设备的准确性是检测结果准确性的重要保证,按规定和要求对仪器进行期间核查,可以确保检测数据的准确可靠。结合仪器设备期间核查的实例说明期间核查是维持设备校准状态的可信度的重要手段。