云南山区公路事故多发路段安全对策措施研究

分析云南山区公路严峻的交通形势,及山区公路交通事故的特征、事故形态及影响因素,研究山区公路交通事故发生的机理。从人、车、路和环境等方面分析事故产生的原因,提出针对云南山区事故多发路段安全对策措施。分析表明,在云南山区,路况、人员安全素质、车辆性能、安全管理均处于较低水平,是重大事故多发的根本原因。提高系统安全性,实现系统功能最强,应使系统各要素相互匹配,以实现本质安全。     

Improved performance of a biomaterial-based cation exchanger for the adsorption of uranium(VI) from water and nuclear industry wastewater

The amine-modified polyhydroxyethylmethacrylate (poly(HEMA))-grafted biomaterial (tamarind fruit shell, TFS) carrying carboxyl functional groups at the chain end (PGTFS-COOH) was prepared and used as an adsorbent for the removal of uranium(VI) from water and nuclear industry wastewater. FTIR spectral analysis revealed that U(VI) ions and PGTFS-COOH formed a chelate complex. The adsorption process was relatively fast, requiring only 120 min to attain equilibrium. The adsorption kinetic data were best described by the pseudo-second-order equation. The equilibrium adsorption data were correlated with the Sips isotherm model. The maximum U(VI) ions uptake with PGTFS-COOH was estimated to be 100.79 mg/g. The complete removal of 10 mg/L U(VI) from simulated nuclear industry wastewater was achieved by 3.5 g/L PGTFS-COOH. The reusability of the adsorbent was demonstrated over 4 cycles using NaCl (1.0 M) + HCl (0.5 M) solution mixture to de-extract the U(VI). The results show that the PGTFS-COOH tested is very promising for the recovery of U(VI) from water and wastewater.     

Accumulation and mobility of zinc in soil amended with different levels of pig-manure compost

Applying manure compost not only results in zinc accumulation in the soil but also causes an increase in zinc mobility and enhances zinc leaching. In this study, the physical and chemical characteristics of zinc, zinc profiles, and zinc balance were investigated to characterise the fate of zinc in fields where the quality and amount of pig manure compost applied have been known for 13 years. Moreover, we determined zinc fractionation in both 0.1 mol L^?1HCl-soluble (mobile) and -insoluble (immobile) fractions. Adsorption of zinc in the soil was enhanced with increasing total carbon content following the application of pig manure compost. The 159.6 mg ha^?1 year^?1manure applied plot (triplicate) exceeded the Japanese regulatory level after only 6 years of applying pig manure compost, whereas the 53.2 mg ha^?1 year^?1 manure applied plot (standard) reached the regulatory level after 13 years. The zinc loads in the plots were 17.0 and 5.6 kg ha^?1 year^?1, respectively. However, 5.9 % and 17.2 % of the zinc loaded in the standard and the triplicate pig manure compost applied plots, respectively, were estimated to be lost from the plough layer. Based on the vertical distribution of mobile and immobile zinc content, a higher rate of applied manure compost caused an increase in the mobile zinc fraction to a depth of 40 cm. Although the adsorption capacity of zinc was enhanced following the application of pig manure compost, a greater amount of mobile zinc could move downward through the manure amended soil than through non manure-amended soil.     

Leaching,mobility and persistence of tebufenozide in columns packed with forest litter and soil

Abstract

Leaching, downward mobility and persistence of tebufenozide was investigated under laboratory conditions in columns packed with forest litter and soil, after fortification with the analytical grade material (purity > 99.6%) and with two commercial formulations, RH‐5992 2F (aqueous flowable) and RH‐5992 ES (emulsion suspension). Two types of litter and soil were used: one type with relatively high amounts of sand and the other with high amounts of clay.

The concentrations eluted in the leachates were lower when the analytical material (dissolved in acetone) was used for fortification, than when the two formulations (diluted with water) were used. The amount leached was higher for RH‐5992 2F than for RH‐5992 ES. The type of substrate, i.e., sandy or clay type, had only marginal influence on the amounts eluted in the leachates. Downward movement of tebufenozide from the top 2‐cm layer to the untreated middle and bottom layers (3‐cm segments) was consistently lower when the analytical material was used for fortification, than when the two formulations were used. Downward movement was higher for RH‐5992 2F than for RH‐5992 ES. Persistence of tebufenozide in substrates, maintained under submerged conditions for 70 days after leaching, indicated an initial 2‐week lag period prior to the onset of degradation. Formulation‐related differences were observed in the half‐life (DT₅₀) values. When the analytical material was used for fortification, the DT₅₀ ranged from ca 54 to 59 d. However, when the formulations were used for fortification, the DT₅₀ showed a higher range, i.e., from ca 62 to 67 d for RH‐5992 2F and ca 70 to 80 d for RH‐5992 ES. Formulation ingredients appear to have caused enhanced adsorption of tebufenozide onto the substrates, thus delaying degradation.     

Aflatoxin decomposition in various soils

Abstract

The persistence of aflatoxin in the soil environment could potentially result in a number of adverse environmental consequences. To determine the persistence of aflatoxin in soil, ¹⁴C‐labeled aflatoxin B₁, was added to silt loam, sandy loam, and silty clay loam soils and the subsequent release of ¹⁴CO₂ was determined. After 120 days of incubation, 8.1% of the original aflatoxin added to the silt loam soil was released as CO₂ ? Aflatoxin decomposition in the sandy loam soil proceeded more quickly than the other two soils for the first 20 days of incubation. After this time, the decomposition rate declined and by the end of the study, 4.9% of the aflatoxin was released as CO_2. Aflatoxin decomposition proceeded most slowly in the silty clay loam soil. Only 1.4% of aflatoxin added to the soil was released as CO₂ after 120 days incubation. To determine whether aflatoxin was bound to the silty clay loam soil, aflatoxin B₁ was added to this soil and incubated for 20 days. The soil was periodically extracted and the aflatoxin species present were determined using thin layer chromatographic (TLC) procedures. After one day of incubation, the degradation products, aflatoxins B₂ and G₂, were observed. It was also found that much of the aflatoxin extracted from the soil was not mobile with the TLC solvent system used. This indicated that a conjugate may have formed and thus may be responsible for the lack of aflatoxin decomposition.     

Thermodynamics of interaction of lindane on silty loam and silty clay loam Indian soils

Abstract

Interaction of lindane with silty loam and silty clay loam soils was studied in batch tests at 23, 30 and 37° C. Sorption experiments were carried out at four concentrations and for varying time of contact upto 72 hours. This was followed by desorption studies. No desorption was observed. The sorption data was analysed using sorption equations and evaluating the thermodynamic parameters. The sorption was found to be predominantly entropic in nature and a combined effect of adsorption and chemisorption. The effect of organic matter and other chemical and mineralogical constituents of soils has also been discussed. The sorption with single application of lindane with the two soil types indicates that the insecticide is less likely to reach groundwater.     

SOIL WATER CHARACTERISTICS OF TWO SOIL CATENAS IN ILLINOIS: IMPLICATIONS FOR IRRIGATION1

ABSTRACT: Soil water was monitored by neutron scattering in six soils, three each within two drainage catenas in east-central Illinois, over a 15-month time span. The prairie soils have formed in: (1) 76–152 cm of silt loam, eolian sediments (bess) over glacial till (Catlin-Flanagan-Drummer catena), and (2) bess greater than 152 cm in thickness (Tama-Ipava-Sable catena). We characterized the water content of these soils over the total time span and for wet and dry climatic subsets, as an aid to potential irrigation decisions. Soils of the thin bess, C-F-D catena dried out to lower water contents and had greater soil water variability than did the thick bess soils. Under wet conditions, soil water contents in the two catenas were quite similar. Alleviation of surface and subsurface drying via irrigation would thus be more advantageous to yields on the C-F-D soils than on the T-I-S soils.     

核废物的来源、特性与分类原则的研讨

本文阐述了核废物的产生，特性和环境影响；对核废物的分类，处理和处置原则进行了讨论。     

IN SITU MEASUREMENT OF ADSORPTION AND BIOTRANSFORMATION AT A HAZARDOUS WASTE SITE1

ABSTRACT: A three well injection-production test was performed at the United Creosoting Company (UCC) site in Conroe, Texas, to estimate the effective in situ retardation factors for adsorption and to evaluate the significance of biotransformation in limiting the transport of polycydic aromatics present in the shallow aquifer. The field test was also used as a model to determine if this type of testing would be feasible at other hazardous waste sites. During the test, chloride, a non-reactive tracer and two organic compounds, naphthalene and paradichlorobenzene (pDCB), were injected into a center well for 24 hours followed by clean ground water for six days. Ground water was continuously produced from two adjoining wells and monitored to observe the breakthrough of these compounds. Data from the test were analyzed by comparing the statistical moments of the chloride and organics distributions. Retardation factors for naphthalene and pDCB were estimated to be 1.03 and 0.97 by comparison of the statistical moments. A significant loss of naphthalene and pDCB was also observed during the three well test, apparently due to biotransformation. These results suggest that biotransformation is the major process limiting the transport of naphthalene and similar compounds at the UCC site.     

改性树脂NKZ对水溶性染料的吸附特性研究

根据聚合物絮凝剂与染料相互作用机理,用硝基胍对大孔型氯球改性得到了功能化吸附树脂NKZ.从热力学和动力学两方面研究了该树脂对5种水溶性染料的静态吸附特性.结果表明,树脂NKZ对水溶性染料的吸附具有很好的效果.