Selection of sorption material for tests of pesticide permeation through protective clothing fabrics.

The paper presents the results of studies on selecting a solid sorption material for absorbing liquid crop protection agents which permeate samples of protective clothing fabrics. The sorption materials were investigated and selected with an assumption that they should have a high recovery coefficient for biologically active substances, used as active ingredients in crop protection agents, at a presumed, acceptably high level. The selected substances were determined with a gas chromatograph equipped with an electron capture detector (dichlorvos, cypermethrin and 2,4-D) and a nitrogen-phosphorus detector (carbofuran). The tests demonstrated that polypropylene melt-blown type unwoven cloth had high recovery coefficients for all 4 active ingredients proposed for the study. The highest recovery coefficient, -.97, was obtained for carbofuran. The recovery coefficients obtained for the 3 remaining substances were lower: .89 for cypermethrin and 2,4-D, and .84 for dichlorvos.     

沿空窄煤柱锚网带支护的巷道稳定性研究

锚杆支护是煤矿采准巷道的重要支护方式 ,沿空留巷技术是回采巷道支护技术改革的主要方面。笔者将两种技术相结合 ,用于保证回采巷道的稳定。在现场矿压观测的基础上 ,讨论了支承压力分布规律和窄煤柱护巷机理 ,运用极限平衡理论计算出护巷煤柱宽度 ,同时结合数值分析和现场巷道变形以观测结果 ,实践证明 ,只要设计参数合理 ,施工质量满足要求 ,沿空窄煤柱锚网带支护技术就可以保证回采巷道的稳定     

Estimating nitrate leaching with a transfer function model incorporating net mineralization and uptake of nitrogen

Because of the complex interaction of chemical and biological processes of nitrogen (N) in soils, it is difficult to estimate the leaching of nitrate with various N transformations in porous media. In this study, a transfer function model was developed to simulate the outflow concentration of nitrate in soils during the growth of winter wheat (Triticum aestivum L.), taking into account the main N transformations using source and sink terms. The source and sink terms were treated as inputs to the solute transport volume and incorporated into the transfer function model to characterize their effects on nitrate concentration in the outflow. A field experiment was conducted in three nonweighing lysimeters for 181 d. Nitrate concentrations were measured along the 2-m soil profile of each lysimeter at different times. Comparison between the experimental data and simulated results with the transfer function showed that the model provided reasonable prediction of the nitrate leaching process as well as the total amount leached. Results also indicated that considering the N transformations in the transfer function significantly increased the estimation accuracy. The relative errors of total amount leached were < 7% with the N transformations included, but up to 17% without including the transformation processes.     

Arsenic distribution in Florida urban soils: comparison between Gainesville and Miami

Arsenic contamination is of concern due to its effect as a carcinogen. Understanding the distribution of arsenic in urban soils is important for establishing baseline concentrations from which anthropogenic effects can be measured. The soil cleanup target level (SCTL) for arsenic in Florida (0.8 and 3.7 mg kg(-1) in residential and commercial areas, respectively) is lower than in most states and is near the arsenic background concentrations in Florida soils. The objective of this study was to characterize the distribution of arsenic in the soils of two Florida cities, Gainesville and Miami. More than 200 soil samples were collected from three land-use classes in each city (residential, commercial, and public land), digested with USEPA Method 3051a, and analyzed with graphite furnace atomic absorption spectrophotometry. Arsenic concentrations varied greatly in Gainesville, ranging from 0.21 to approximately 660 mg kg(-1) with a geometric mean (GM) of 0.40 mg kg(-1) (after discarding outliers), which was significantly lower than the GM of 2.81 mg kg(-1) in Miami, although Miami samples ranged only from 0.32 to approximately 110 mg kg(-1). Arsenic concentrations in 29 and 4% of the Gainesville soil samples and 95 and 33% of the Miami samples exceeded the Florida residential and commercial SCTL, respectively. This study is the first to provide information on arsenic distribution in urban soils of Florida, and the data are useful for assessing arsenic contamination and determining the need for remediation.     

Degradation of soil environment in the post-flooding area: content of polycyclic aromatic hydrocarbons (PAHs) and s-triazine herbicides

Impacts of flooding on the soil environment with regard to soil pollution with polycyclic aromatic hydrocarbons and s-triazine (cyanazine, simazine, atriazine, propazine, prometryn) herbicides have been evaluated. No clear differences in the sum of the PAHs content were observed in the present studies. Only changes in the levels of individual PAHs were noted. In soils covered with flooding both at a depth of 0-20 and 20-40 high molecular weight PAHs were predominant (especially mutagenic and carcinogenic 5-rings PAHs) whereas in non-flooded areas, 2- and 3-rings PAHs constituted over 80%. In the case of s-triazine herbicides, no influence of flooding on the changes in their content in agriculturally used soils was noted. On the other hand, clearly lower levels of cyanazine, simazine and atriazine were not in the flooded forest soil as compared to the non-flooded forest soil.     

Geotrupine beetles (Coleoptera: Scarabaeoidea) as bio-monitors of man-made radioactivity

Adults of the geotrupine beetle Anoplotrupes stercorosus (Coleoptera, Geotrupidae), a common European forest insect species, were used in the role of bio-monitors for mainly man-made radionuclides in a forest environment. Activities of 137Cs, 40K, 238Pu, (239+240)Pu, 90Sr and 241Am were studied. Samples originated from four areas in Poland, two from the north-east and two from the south of the country. The north-eastern areas were previously recognized as the places where hot particle fallout from Chernobyl took place. Results confirmed the differences in the activities between north-eastern and southern locations. Significant correlations were found between activities of 40K and 137Cs, and between activities of plutonium and americium isotopes. An additional study of the concentration of radionuclides within the bodies of beetles showed a general pattern of distribution of radioisotopes in the insect body.     

重庆市旅游资源开发与旅游产业发展对策

本文在列举了重庆旅游资源的优势和特点的基础上,阐述了旅游业对发展重庆经济的功能;并就重庆市旅游规划的格局,以及如何保持该市旅游业持续、健康地发展提出了相应的对策。     

长江中下游地区旱涝气候年景和评定方法的研究

采用经过修改的Z值指标,利用1961～1995年5～9月的总降水量,建立了长江中下游地区7省市逐年的旱涝等级序列;同时通过计算干旱指数、洪涝指数和旱涝综合指数,对长江中下游地区的旱涝和旱涝气候年景进行了评定,初步实现了气候年景评定从定性向定量的转变,并得到一致的可比的历史序列。     

防灾减灾系统工程的国际对比分析及建议

针对我国现存的灾害状况,本文通过国际对比的方法,对其他国家已有的减灾系统工程作了简单介绍,并结合我国实际,对未来建立减灾系统工程中应着重加强的薄弱环节作了分析,提出了加强立法工作,增加减灾投入,建立全国统一的减灾通讯系统的建议。     

Estimation of Emissions of γ-Hexachlorcyclohexane from the Great Lakes–St. Lawrence Ecosystem Using a Coupled Efficient Kalman Filter–Atmospheric Transport–Soil Model

An efficient linear Kalman filter has been combined with a coupled atmospheric transport and soil–air exchange model to determine organochlorine pesticides emissions on the regional scale. In this study, results of -HCH emissions from the Great Lakes–St. Lawrence ecosystem, estimated from the coupled model, are presented and discussed. A source receptor technique is used to identify a priori the locations of emission sources of -HCH, the emissions are then updated through a Kalman filtering procedure which minimizes the weighted difference between the predicted mixing ratios from the coupled model and the measured concentrations over the Great Lakes–St. Lawrence river region. Two experiments using the inverse algorithm are carried out. In the first experiment, the coupled atmospheric transport and soil–air exchange model is implemented to predict -HCH air and soil concentrations. Emissions are then updated every 12 days using the updated soil concentrations and emission factors. However, the updated emissions are not input into the coupled atmospheric transport and soil–air exchange model. On the other hand, in the second experiment the updated emissions are fed back to the coupled model, so that the model is reinitialized in each 12 days. The results from the inverse technique for the year 1995 have been compared with grided -HCH emission inventory in Canada, generated by emission factors. It is shown that the estimated emissions of -HCH are consistent with the measured emissions. It is found that the St. Lawrence valley has larger emissions of -HCH than the Great Lakes region, indicating an opposite distribution to the emission usage inventory, but in agreement with the measured -HCH concentration.