Calibration for the determination of 19 trace elements in serum and urine

A fast, high-throughput and accurate method was developed for determination of Al, As, Ba, Cd, Co, Cr, Cs, Cu, Fe, Mn, Ni, Pb, Se, U, Zn, Sb, Sn, I and Hg in urine and serum by inductively coupled plasma mass spectrometry. The samples were directly analyzed after 1/20 (v/v) dilution in 0.4% (v/v) HNO₃ and 0.005% Triton X-100. Three calibration modes were tested: aqueous and matrix matching with urine and serum. The accuracy was tested using reference materials of serum, urine and spiking. Results showed that the use of matrix matching calibration reduced the interferences and improved the recoveries for Al, Co, Pb and I in urine. The matrix matching did not affect the results considerably for serum. When serum was spiked with As, Co, Cs, Pb, U, Hg, I, Ba, Al, Cr and Ni, only matrix matching presented good recoveries. Helium was used as a collision cell gas reducing effectively polyatomic interferences for Al, Mn, Cu, Ni, Cr, Zn, As and Fe. Selection of the best internal standard was carried out for each element. The use of diluted HNO₃ improved the limit of detection. Finally, the method was applied successfully in samples of urine from workers occupationally exposed.     

三波段积分浑浊度仪的检测和校准

在兰州大学半干旱气候与环境观测站(SACOL)长期观测运行的基础上,针对测量气溶胶散射特性的三波段积分浑浊度仪(TSI3563)的校准和检测问题进行了探讨.讨论了TSI浊度仪检测和校准气体的选择,零气主要使用经高效微粒空气过滤器过滤的干净空气,标准气体主要使用CO2;总结出浊度仪零气检测和标准气体检测的理论依据,每天零气检测时,散射系数的变化范围为 ,平均值范围为 ,当超出这个范围就需要进行零点设定,每3~5d进行标准气体检测时,散射系数的平均值和理论计算值的误差超出 的范围,就需要进行全校准;最后介绍了零气校准和全校准的方法.     

Modeling agricultural non-point source pollution in a high-precipitation coastal area of China

Non-point source （NPS） pollution simulation in the high-precipitation coastal areas of China is difficult because varying annual typhoon incidence leads to highly contrasting rainfall patterns in dry years and wet years. An IMPULSE （Integrated Model of Non-point Sources Pollution Processes） based NPS model of the Changtan Reservoir watershed, which is a typical high-precipitation coastal area in China, was established based on the analysis of point and NPS pollution data, a digital elevation model, and data on land-use, soil, meteorology, economy, and agricultural management practice. Pre-processed pre-rain- fall soil moisture levels were introduced during the simulation to model the effects of typhoons on hydrology. Rainfall events were simulated sequentially through the year and the model was calibrated and verified using hydrological and water quality data. Accuracy of the simulated rainfall runoff and water quality in the Changtan watershed was found to be acceptable. The study showed that the NPS modeling system could be applied to the simulation and prediction ofNPS loadings in the Changtan Reservoir watershed.     

HYDROLOGIC MODELING AT THE WATERSHED SCALE USING NPSM1

ABSTRACT: The Nonpoint Source Model (NPSM) was chosen for nonpoint source pollutant modeling within three different watersheds. The first step in using NPSM, hydrologic calibration, is discussed here for three 8‐digit Hydrologic Unit Codes (HUCs) from the White River Basin in Indiana (Driftwood HUC), the Albemarle‐Pamlico River Basin in Virginia and North Carolina (Contentnea HUC), and the Apalachicola‐Chattahoochee‐Flint River Basin in Alabama, Georgia, and Florida (Ichawaynochaway HUC). Model predicted flows were compared statistically with USGS gauge data at the HUC outflow points for an uncalibrated and calibrated model run for the period from January 1, 1990, through December 31, 1992, and a validation run for the period from January 1, 1993, through December 31, 1995. Least squares regression of NPSM predicted flows versus USGS gauge data were 0.75, 0.44, and 0.69 for the calibration runs and 0.71, 0.69, and 0.64 for the validation runs in the Driftwood, Contentnea, and Ichawaynochaway HUCs, respectively. Nash Sutcliffe coefficient values were not as strong, ranging from ?0.66 to 0.45 for the calibration runs and 0.31 to 0.37 for the validation runs of the model. The Ichawaynochaway HUC proved the most difficult to calibrate indicating that the model may not be as useful in some geographic locations.     

单推三校正系数在光离子化检测器应用中的测量研究

在利用光离子化检测器监测单推三推进剂贮存环境时,必须首先要知道单推三相对于光离子化检测器校准气体的校正系数。通过简要介绍了校正系数的测量计算原理,并进行实验测量计算,求得单推三的校正系数。     

SENSITIVITY CONSIDERATIONS WHEN MODELING HYDROLOGIC PROCESSES WITH DIGITAL ELEVATION MODEL1

ABSTRACT: The purpose of this paper is to investigate the sensitivity of a hydrologic models to the type of DEM used. This was done while modeling basin water quality with 1:24,000 and 1:250,000 U.S. Geological Survey DEMs as input to model hydro‐logical processes. The manner in which the model results were sensitive to the choice of raster cell size (scale) is investigated in this study. The Broadhead watershed, located in New Jersey, USA, was chosen as a study area. Curve numbers were estimated by a trial and error to match simulated and observed total discharge. Monthly runoff for the watershed was used in the calibration process. Higher runoff volumes were simulated by the model when the 1:24,000 DEM were used as input data, probably due to the finer resolution which simulated increased average slope and hence higher estimated runoff from the watershed. As the simulated slope of the watershed is flatten with the 1:250,000 DEM, the response of stream flow was delayed and simulated less runoff volume.     

单级活性污泥过程数学模型ASM2D参数的灵敏度分析

利用单级活性污泥模拟流程对ASM2D参数的灵敏度进行了研究,发现在67个化学计量系数及动力学常数中,有22个参数需在应用中进行校核．该项研究结果为ASM2D实际应用中减少需校核参数的个数提供了依据．     

Critical ranges of pollution indices: a tool for predicting soil metal pollution under long-term wastewater reuse

A greenhouse experiment was conducted in pots, for two years (2015–2016), in Amaliada, Greece, using a randomized block design, including six treatments with mixtures composed of Zn, Mn, Cd, Co, Cu, Cr, Ni, and Pb, each metal taking part in the mixture at concentrations of 0, 10, 20, 30 40, and 50 mg/kg soil in four replicates each. Beta vulgaris (beet) was used as a test plant. The aim of the experiment was to calibrate the following pollution indices: “pollution load index,” “elemental pollution index,” “heavy metal load,” and “total concentration factor,” in order to determine the level of soil pollution under variable levels (low to very high) of metal mixtures. The irrigation of the plants was conducted with treated municipal wastewater based on field capacity and percent wilting point. The above pollution indices were classified into four soil pollution classes, i.e., “optimum,” “low,” “high” and “very high” on the basis of percent dry matter plant losses.     

Applications of Explicitly Incorporated/Post‐Processing Measurement Uncertainty in Watershed Modeling

In the field of watershed modeling, the impact of measurement uncertainty (MU) on calibration results indicates the potential issue of inaccurate model predictions. It is important to note that MU refers to the uncertainty in measured data such as flow and nutrient values that are used to evaluate model outputs. The calculation of error statistics assuming measured data are deterministic may not be appropriate as has been frequently stated in literature. Although MU can affect model calibration results, it is rarely incorporated in modeling practice. MU can be incorporated in two schemes: explicitly incorporated (MU‐EI) during model calibration and post‐processed (MU‐PP) after calibration is completed. In this study, both schemes are implemented in a case study of the Arroyo Colorado Watershed, Texas. Unexpectedly, no substantial differences were observed between each scheme for flow predictions. Although MU did not cause dramatic differences in most sediment and NH₄‐N predictions, error statistics were affected in cases with MU greater than 50%, especially for sediment and NH₄‐N. Therefore, it is concluded that MU may not exert a significant impact on model predictions until certain threshold is reached. This study demonstrates that high levels of uncertainty in measured calibration/validation data significantly affect parameter estimation, especially in the auto‐calibration process.     

Evaluation of various global solar radiation models for Nigeria

This study assessed the performance of six solar radiation models. The objective was to determine the most accurate model for estimating global solar radiation on a horizontal surface in Nigeria. Twenty-two years meteorological data sets collected from the Nigerian Meteorological agency and the National Aeronautics and Space Administration for the three regions, covering the entire climatic zones in Nigeria were utilized for calibrating and validating the selected models for Nigeria. The accuracy and applicability of various models were determined for three locations (Abuja, Benin City, and Sokoto), which spread across Nigeria using seven viable statistical indices. This study found that the estimation results of considered models are statistically significant at the 95% confidence level, but their accuracy varies from one location to another. However, the multivariable regression relationship deduced in terms of sunshine ratio, air temperature ratio, maximum air temperature, and cloudiness performs better than other relationships. The multivariable relationship has the least root mean square error and mean absolute bias error, not exceeding 1.0854 and 0.8160 MJ m^?2 day^?1, respectively, and monthly relative percentage error in the range of ± 12% for the study areas.