一种灾害等级的区间数评估模型

由于灾害损失本身的复杂性及灾情统计方面存在的问题,利用区间数替代单一实数值作为灾害等级评估指标的输入更加符合实际。基于上述思路,提出了一种基于区间数的灾害等级评估新模型。首先,给出区间数距离的新定义,该定义能够充分利用区间数所携带的信息;然后,利用线性加权评价函数计算评估对象与评价标准之间的综合相对距离测度,评估对象隶属于综合距离测度最小值所对应的灾害等级。该模型建模过程思路清晰,物理意义明确,计算过程简捷,评估结论符合实际。最后,用实例说明模型的应用方法。     

利用磁信息研究潮滩重金属污染的探讨

本文以长江口潮滩沉积物的系统磁性测量为基础,对照化学分析和粒度分析等数据,初步探讨了潮滩沉积物的磁性特征与重金属元素含量的相关联系及其机理,建立了重金属元素含量与磁参数的定量关系模型,并揭示了长江口潮滩重金属污染的空间特征及其与沉积环境的联系。本项工作成功地探索了利用磁信息研究潮滩重金属污染的技术路线和应用前景,指出了在一定区域内,利用适量样品的磁性测量与重金属元素分析数据,建立其定量回归模型的可行性。从而可以在区域污染调查中,通过广泛的磁数据测量,由经验公式定量地估算不同滩地部分的重金属元素含量,以全面了解潮滩重金属污染的空间分布,分析其规律和机理。由于磁测方法具有快速、简便、经济、易行等特点,它为大范围的潮滩重金属污染研究提供了一项实用有效的辅助手段。     

Validation of the operational emergency response model at the Swedish Meteorological and Hydrological Institute using data from etex and the chernobyl accident

The Eulerian atmospheric tracer transport model MATCH (Multiscale Atmospheric Transport and Chemistry model) has been extended with a Lagrangian particle model treating the initial dispersion of pollutants from point sources. The model has been implemented at the Swedish Meteorological and Hydrological Institute in an emergency response system for nuclear accidents and can be activated on short notice to provide forecast concentration and deposition fields.The model has been used to simulate the transport of the inert tracer released during the ETEX experiment and the transport and deposition of ¹³⁷Cs from the Chernobyl accident. Visual inspection of the results as well as statistical analysis shows that the extent, time of arrival and duration of the tracer cloud, is in good agreement with the observations for both cases, with a tendency towards over-prediction for the first ETEX release. For the Chernobyl case the simulated deposition pattern over Scandinavia and over Europe as a whole agrees with observations when observed precipitation is used in the simulation. When model calculated precipitation is used, the quality of the simulation is reduced significantly and the model fails to predict major features of the observed deposition field.     

我国汽车尾气污染,污染控制与对策

本文综述了我国汽车尾气污染的现状与发展趋势，着重阐述了我国汽车尾气的催化剂研制和催化净化器技术水平和现状，提出了我国汽车尾气污染控制技术的发展方向，并探讨了减少汽车尾气污染的对策和建议。     

Effects of degree of water saturation on dispersivity and immobile water in sandy soil columns

Three natural nonaggregated soil samples, with similar grain-size distributions, have been used to determine the dispersive behavior of porous media under steady, saturated and unsaturated flow conditions. Tritium was used as a tracer and was found to have no sorption on the solid matrix. Generated breakthrough curves (BTCs) for the unsaturated experiments were symmetrical with no evidence of tailing. The unsaturated experiments for two of the soils were adequately described by considering all the water in the pore volume as mobile. However, about 10% of the pore water, independent of the degree of saturation, was found to be immobile in the case of the third soil during unsaturated flow. For this soil, there was no mass transfer between the two water regions, indicating that the immobile water is essentially isolated from the flowing water fraction. For all three soils, dispersivity under unsaturated conditions was found to be higher, independent of the degree of water saturation, than the value determined for the saturated experiments. This is inconsistent with what would be expected from the simple bundle-of-capillary-tubes model and does not agree well with a more sophisticated conceptualization of the porous medium. The data, however, clearly indicate a wider range in pore-water velocities when these soils are desaturated.     

Surface complexation modeling of Yb(III) sorption and desorption on hematite and alumina

Sorption and desorption of Yb(III) were studied on hematite and on alumina using a surface complexation model. The experimental methodology was conceived to allow an analysis of the data using a constant capacitance model. The FITEQL code was used for the calculations.The experimental results tend to show reversibility of sorption when the surface loading is small, and irreversibility when the surface loading is high. Surface complexation modeling gives a good interpretation of these two phenomena, taking into account hydroxylation of the surface complexes. In these two cases, it is possible to describe sorption and desorption curves with the same surface stoichiometries and the same surface complexation constants. The existence of these surface complexes depends on the pH of the solution, surface loading, and reaction direction.     

Regression modelling of hourly NOx and NO2 concentrations in urban air in London

Based on hourly measurements of NO_x NO₂ and O₃ and meteorological data, an ordinary least squares (OLS) model and a first-order autocorrelation (AR) model were developed to analyse the regression and prediction of NO_x and NO₂ concentrations in London. Primary emissions and wind speed are the most important factors influencing NO_x concentrations; in addition to these two, reaction of NO with O₃ is also a major factor influencing NO₂ concentrations. The AR model resulted in high correlation coefficients (R > 0.95) for the NO_x and NO₂ regression based on a whole year's data, and is capable of predicting NO₂ (R = 0.83) and NO_x (R = 0.65) concentrations when the explanatory variables were available. The analysis of the structure of regression models by Principal Component Analysis (PCA) indicates that the regression models are stable. The results of the OLS model indicate that there was an exceptional NO₂ source, other than primary emission and reaction of NO with O₃, in the air pollution episode in London in December 1991.     

Mercury pollution and macrophage centres in pike (Esox lucius) tissues

From June 1993 to October 1994, studies have been carried out on the effects of mercury in the Oder River and pike tissue contamination (muscle, kidney, liver). The mean mercury contents in the sediment range from 0.03 to 1.1 mg/kg dry weight. In the pike muscle, between 0.22 and 0.85 mg/kg, on a wet weight basis, were found. The measured mercury concentrations were analysed in relation to the number of macrophage centres of the liver, spleen and kidney of the pike. Positive correlations between mercury and MC response (0.54 ≤ r ≤ 0.79, p < 0.05) were found in all of these organs. The suitability of the macrophage-centre-response as a possible bioindicator for mercury pollution is discussed in the literature. In our study, the response of MCs was found to be suitable as a biomarker for the impairment of fish health.     

华北农村水环境污染评价及源解析

近年来,国家相继发布多项重要文件要求整治农村人居环境、建设美丽乡村,但当前针对农村水环境问题研究相对较少,制约了农村环境治理工作开展。选取华北某镇农村河道坑塘,评价农村水环境污染水平、生态风险并进行污染溯源。结果表明,57处调查点位中有1处水体黑臭,但有多处调查点位水体溶解氧在2~3 mg∙L⁻¹、透明度在25~35 cm、氨氮在8~15 mg∙L⁻¹,接近黑臭阈值。仅有约9%的水体全部水质指标均能满足地表水V类要求 (检测指标为18项) ,超标指标主要为pH、COD_Mn、BOD、氨氮、总磷、总氮、粪大肠菌群等8项。底泥总磷、总氮标准指数分别处于中度、重度污染状态,营养盐综合指数属于重度污染状态。底泥存在不同程度的重金属富集,铜、锌、汞、镉、铬、铅、砷、镍等8项重金属的平均浓度是天津土壤背景值的0.45~2.73倍。汞的地累积指数平均值为0.64,为轻度污染;铜、锌、镉、铬、铅、砷、镍等其他7项重金属为清洁状态。汞的潜在生态风险指数约110,为较高生态危害;其他7项重金属生态风险指数均小于80,为轻微生态危害。综合Pearson相关性、主成分及PMF分析,研究区重金属最主要的污染来源是交通源和大气沉降,其次是工业源,最后是农业源。总体来看,研究区水体水质较差,沉积物有重金属轻度富集,其中汞是沉积物生态风险的主要贡献元素。     

基于村庄分散度的农村生活污水治理模式量化分析

随着农村地区生活水平的提升,生活污水所含污染物成分趋于复杂化,未经处理就地排放对生态环境影响不容小觑。目前,农村生活污水治理模式种类多样,但决策方法缺乏科学依据。以内蒙古地区82个村落为研究对象。以自然村落为最小研究单元,利用村落宅基地占比、村落长宽比、周长、极限距离、坡度0°~8°占比和坡度标准差等指标,构建了居住密度决策树 (准确率76%) 以及地势决策树 (准确率88%) 。决策树所得结果通过二分类概率单位回归 (Probit)分析 (准确率87%) ,确定其村落集中或分散情况,进而选择适宜的村落污水治理模式 (集中模式、纳管模式、分散模式、拉运模式、就地利用模式) 。农村生活污水治理模式决策方法的确立决策指标的量化,为促进农村生活污水治理体系的发展、提升污水治理的有效性具有积极意义。