重金属在环境中的化学形态分析研究进展

重金属在环境中的形态与迁移转化决定了其污染风险和生物有效性.本文从影响重金属形态的主要环境条件和结合物特性出发,分析了重金属在环境中与有机物、无机矿物质等的交互作用机理,对目前重金属形态分析的主要研究方法(化学提取、电化学、分子尺度仪器检测技术、模型计算等)展开综述与讨论.     

Ⅲ型储氢气瓶内胆6061-T6铝合金的氢致损伤研究进展

基于在多次循环充、放氢过程中,Ⅲ型储氢气瓶6061-T6铝合金内胆内部结构中渗入氢,从而导致性能衰减,影响气瓶服役安全可靠性,文中从氢渗透损伤、高压气体渗氢、溶液渗氢等几个方面综述了国内外开展包括6061铝在内的铝及铝合金中氢渗透行为及对铝合金拉伸力学性能、疲劳性能的影响的研究进展.简述了采用高压气体渗氢及溶液渗氢开展...     

便携式烟气SO_2监测仪的原理与应用

便携式烟气ＳＯ２ 监测仪目前已经成为锅炉污染源监测的主要手段。从仪器的原理入手,通过介绍仪器的结构和工作过程,对仪器应用中的标定、校准、现场测试的步骤给以介绍,并给出了仪器法和碘量法的对比测试结果。     

Aqueous and organic extracts of Trigonellafoenum-graecum L. Inhibit the mycelia growth of fungi

Aqueous extracts from various plant parts of fenugreek(3%)(aerial parts:leaves and stems(LS),roots(R),ground seeds(GS)and not ground seeds(NGS))and petroleum ether,ethyl acetate and methanolic fractions of the aerial parts were assayed to determine their antifungal potential against Botrytis cinerea,Fusarium graminearum,Alternaria sp.,Pythium aphanidermatum,and Rhizoctinia solani.All fenugreek plant parts showed antifungal potential and the magnitude of their inhibitory effects was species and plant parts d...     

What is a static head measurement? Evaluating structural error and implications for regional groundwater modeling

Most groundwater modelers avoid using static heads measured from active production wells because they can introduce a bias into model calibration. However, in the deep confined Cambrian-Ordovician Sandstone Aquifer System in the Central Midcontinent of North America, dedicated observation wells are sparse and remote from areas of most concentrated pumping. As a result, in areas where drawdown is the greatest and modeling is most needed, only static heads from production wells are available for calibration. This paper evaluates two leading sources of discrepancies in using production well data, spatial and temporal structural error (S.E.). A simple Theis solution is used to evaluate the potential magnitude of spatial S.E. when calibrating a regional MODFLOW model with coarse cell resolution. Despite theoretical analyses indicating that spatial S.E. could be significant, statistical analysis of the model results suggests that temporal S.E. is dominant. Long (ranging over decades) or frequent (monthly) head datasets are key in understanding temporal S.E., to better capture water-level variability. In this study, the range in static head observations impacted estimates of the remaining time a well could extract water from the aquifer by 0.1 to 16.0 years. This uncertainty in future water supply is highly relevant to stakeholders and must be assessed in hydrographs depicting risk.     

中国地区太阳分光辐射观测网的建立与仪器标定

大规模的太阳分光地基联网观测不但能够直接为该项研究提供基础数据,同时也可为卫星遥感提供地表订正.利用性能优越的LED型太阳光度计,依托中国生态研究网络(CERN)分布在中国各地的观测站,建立了标准的太阳分光辐射观测网.利用Langley定标法结合量值传递定标法对观测网所有光度计的标定方法及误差分析表明,不同光度计间的同步观测结果(相对标准偏差小于3%)以及与CIMEL光度计的观测结果间(相对偏差小于5%)有很好的一致性,证实了观测结果的准确性以及该类型光度计及其观测网的稳定性和可靠性.     

Application of SWAT with and without Variable Source Area Hydrology to a Large Watershed

In this study, two different versions of the Soil and Water Assessment Tool (SWAT) model were used to simulate the hydrology and biogeochemical response of the Cannonsville Reservoir watershed, in New York. The first version distributes overland flow in ways that are consistent with variable source area (VSA) hydrology driven by saturation excess runoff, whereas the second version is the standard version of SWAT. These two models were each calibrated for streamflow (Flow), particulate phosphorus (PP), total dissolved phosphorus (TDP), and sediment (Sed) against measured data from the 1,200 km² Cannonsville watershed. The standard version of the model yielded an r² between the measured and simulated data of 0.85, 0.73, 0.70, and 0.72 for Flow, Sed, TDP, and PP, respectively. The VSA version yielded an r² of 0.84, 0.69, 0.72, and 0.53 for Flow, Sed, TDP, and PP, respectively. The two models were then used to determine the maximum upper bound on the reduction in phosphorus loading by removing all of the corn in the watershed. The average reductions between the two models were 65 and 37% for PP and TDP, respectively. The VSA version was also used to estimate the effect of moving corn land in the watershed from the wettest, most runoff prone areas to the driest, least runoff prone areas, which cannot be done directly with the standard SWAT model.     

模拟太阳光作用下间甲酚的水相和冰相光转化研究

本文研究了在模拟太阳光作用下间甲酚的水相和冰相光转化规律.考察了不同浓度的H2O2、NO-2和NO3^-对间甲酚光转化的影响,建立了不同条件下间甲酚光转化的动力学方程.结果表明,在模拟太阳光作用下间甲酚在水相和冰相中均可以发生光转化,间甲酚的冰相光转化速率小于水相.在本实验条件下,H2O2和NO2^-促进了间甲酚在水相...     

Revisiting Kappa to account for change in the accuracy assessment of land-use change models

Land-use change models are typically calibrated to reproduce known historic changes. Calibration results can then be assessed by comparing two datasets: the simulated land-use map and the actual land-use map at the same time. A common method for this is the Kappa statistic, which expresses the agreement between two categorical datasets corrected for the expected agreement. This expected agreement is based on a stochastic model of random allocation given the distribution of class sizes. However, when a model starts from an initial land-use map and makes changes to it, that stochastic model does not pose a meaningful reference level. This paper introduces K_Simulation, a statistic that is identical in form to the Kappa statistic but instead applies a more appropriate stochastic model of random allocation of class transitions relative to the initial map. The new method is illustrated on a simple example and then the results of the Kappa statistic and K_Simulation are compared using the results of a land-use model. It is found that only K_Simulation truly tests models in their capacity to explain land-use changes over time, and unlike Kappa it does not inflate results for simulations where little change takes place over time.     

己唑醇在水溶液中的光化学降解研究

研究了高压汞灯光源下己唑醇在不同pH缓冲液中的光化学降解特性及NO3-和NO2-对光解的影响.结果表明,己唑醇在水溶液中的光解符合一级动力学规律.不同pH值缓冲溶液中的光解速率排序为:pH=7>pH=9>pH=5.在己唑醇水溶液中添加不同浓度的NO3-及NO2-,均会不同程度地影响己唑醇的光解速率.在0～20mg·L-1的浓度范围内,NO3-对己唑醇的光解均表现为促进作用,且随着添加浓度的增大促进作用增强;NO2-在0.4和2mg·L-1浓度下,对己唑醇的光解有一定的促进作用,而在10～20mg·L-1浓度时,表现为抑制作用.