我国放射性物质运输概况

本文介绍了我国放射性物质运输概况(除台湾省外)。目前,全国放射性物质货包的年运输最约10万件,总放射性活度为1.8PBq,运输的放射性同位素主要是~(131)I、~(32)P 和~(198)Au 等。承运人员的年剂量当量是相当低的,一般小于5mSv。由于十分重视放射性物质的安全运输,所以没有发生过严重事故。文中还讨论了放射性物质运输中的防护问题。     

Feasibility of fishmeal replacement by shrimp head silage protein hydrolysate in Nile tilapia (Oreochromis niloticus L) diets

This study provides information on the use of shrimp head silage protein hydrolysate (SPH) as an alternative protein source for tilapia feeding. Six diets (28% protein, 12% lipid) were prepared where fishmeal protein was replaced at levels of 0 (control), 10, 15, 20, 25 and 30% with the hydrolysate. The diets were supplied to Nile tilapia fry (338 mg initial weight) stocked in plastic recirculating 20 l tanks (10 animals per tank), with three replicates per treatment. After an 8 week experimental period, fish fed the diets containing 10 and 15% SPH showed significantly better performance in terms of final body weight, weight gain (%), mean daily weight gain (mg day^?1), specific growth ratio and feed conversion ratio than those fed the control diet (fishmeal as protein source) and higher‐SPH diets. It is concluded that shrimp head hydrolysate is a promising alternative protein source for tilapia feeding, improving growth ratio at dietary inclusion levels as high as 15%. In addition, the diets with added shrimp silage protein were well accepted by the fish, which avidly consumed the feed during the experiment. © 2002 Society of Chemical Industry     

Capture of Airborne Particulate Using Surface Applied Emulsions: Potential for Postdetonation Dirty Bomb Cleanup

Recent research has proposed the use of asphalt and tall-oil-pitch emulsions for stabilizing radioactive contamination deposited on surfaces in urban areas. The objective of this project was to investigate whether surface applied emulsions could capture airborne radioactive particulate. Laboratory experiments included wind-blown particulate capture studies using an acrylic column and particulate retainment experiments using a wind box capable of producing wind speeds of 96?km/h. A probe methodology was developed to relate particulate retainment to a tack force on the emulsion surface. Experiments were also performed to determine the potential for such emulsions to absorb particulate matter into their emulsion matrix. Tall-oil-pitch emulsions outperformed asphalt emulsions in terms of particulate retention, tack force, and the ability to absorb magnesium silicate. Both tall-oil-pitch and asphalt emulsions were capable of extracting 22–24?g?m?2 of powder from particulate-laden airflow. Tall-oil-pitch emulsions were capable of retaining as much as 5–10% of magnesium silicate powder applied (i.e., retainment densities of 10–20?g?m?2) even after seven?days of curing and after applying 96.5?km/h (60?mph) wind. Tall-oil-pitch emulsions were able to absorb surface-applied magnesium silicate (approximately 0.1–0.2?g of magnesium silicate per 1.0?g of emulsion within three?days) into their emulsion matrix, preventing the magnesium silicate from being exposed to the external environment. Initial results with these five different emulsion formulations suggested particulate capture was feasible. Future emulsion formulations (i.e., longer curing times with greater acid concentrations) should be tested to optimize this postdetonation response strategy.     

A coordinated reverse logistics system for regional management of multi-source hazardous wastes

This paper presents a coordinated reverse logistics (CRL) management system for the treatment of multi-source hazardous wastes in a given region, in this case, a specific high-technology manufacturing zone. A linear multi-objective analytical model is formulated that systematically minimizes both the total reverse logistics operating costs and corresponding risks. In addition to inter-organizational logistics operating factors, environmental concerns are considered and formulated as corresponding risk-related constraints. Using the proposed model, results of numerical studies indicate that when the aspect of risk-induced penalties is not considered, the operational costs of regional hazardous-waste management can be efficiently reduced by 58%, compared to the existing operational costs at the study site. In addition, it is also observed that the corresponding weight associated with the risk-induced objective function embedded in the proposed model seems to have a significant effect on the CRL costs.     

Electrochemical oxidation of several chlorophenols on diamond electrodes Part I. Reaction mechanism

The electrochemical oxidation of 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol aqueous wastes using boron-doped diamond electrodes was studied. This treatment led to complete mineralization of the wastes regardless of the operating conditions. A simple mechanistic model is consistent with the voltammetric and electrolysis results. According to this model, the electrochemical treatment of chlorophenol aqueous wastes involves the anodic and cathodic release of chlorine followed by the formation of non-chlorinated aromatic intermediates. Subsequent cleavage of the aromatic ring gives rise to non-chlorinated carboxylic acids. Chlorine atoms arising from the hydrodehalogenation of the chlorophenols are converted into more oxidized molecules at the anode. These molecules react with unsaturated C₄ carboxylic acid to finally yield trichloroacetic acid through a haloform reaction. The non-chlorinated organic acids are ultimately oxidized to carbon dioxide and the trichloroacetic acid into carbon dioxide and volatile organo-chlorinated molecules. Both direct and mediated electrochemical oxidation processes are involved in the electrochemical treatment of chlorophenols.     

Carbon mineralization from composts and food industry wastes added to soil

We have studied the short term C mineralization of six wastes from important food industries, one sludge from a biogas plant and three composts. All the wastes were characterized chemically and fractionated according to the Van Soest method. The fresh wastes were incubated under controlled environment conditions to determine the C mineralization rate. Based on first order mineralization kinetics, we calculated the hypothetical amount of stable C in the wastes as the amount of C that would not be mineralized within one year under field conditions. The percentage of stable organic C in the organic matter was in general much larger in the composts than in the other wastes, but when expressed on dry matter, the non-composted wastes had comparable or larger amounts of stable organic C than the composts and have a considerable potential for supplying organic matter to soils, and hence for C sequestration. The amount of stable organic C could best be predicted by the total N content of the wastes (R _a ² = 0.855), whereas the results of the fractionation had very little predictive power, probably due to problems related to the high ash content of some of the wastes. An index that combined stable organic C and N and P content in the wastes was calculated to assess possible limitations for applying these wastes in agriculture. Under current nutrient legislation in Western Europe, a number of these wastes will only be usable in small amounts, but these and other food industry wastes could still prove to be valuable soil amendments in nutrient poor situations, for increasing soil organic C content and supplying nutrients.     

粘土作为高放废物处置回填材料的可行性研究

本文以西北粘土为对象,对其压实行为、热传导、膨胀特性,以及吸附和渗透性能进行了初步研究,借以探讨西北粘土在高放废物处置中用作回填材料的可行性。试验表明,以西北粘土为基材,经过适当的热改性和吸附改性,在初始含水量约为9%,于70MPa 下成型,用作高放废物处置中的回填材料是可行的。     

微机核子秤在大型尿素装置中的应用

介绍了大型尿素装置中微机核子秤的系统构成，测量原理、安装、调校及在调试过程中发现的问题。     

Butyltin Species and Inorganic Tin in Water and Sediment of the Detroit and St. Clair Rivers

Water and sediment samples from 29 locations in the Detroit and St. Clair rivers were analyzed for the highly toxic tri-n-butyltin (Bu₃Sn⁺) species and for the less toxic di-n-butyltin (Bu₂Sn²⁺) and n-butyltin (BuSn³⁺) species and inorganic tin. In general, locations sampled in the St. Clair River were less contaminated with butyltin species than those in the Detroit River. Inorganic tin and BuSn³⁺ were detected in over 90% of all subsurface water samples, while Bu₂Sn²⁺ and Bu₃Sn⁺ were detected in 45 and 28% of the same samples, respectively. The highest concentration ofBu₃Sn⁺ in subsurface water, 5.9 × 10^?10 mol Sn/L, was at the mouth of the Ecorse River, a tributary of the Detroit River. The three butyltin species and inorganic tin were also detected in 23–46% of all sediment samples. The highest concentrations of Bu₃Sn⁺ in sediment were found close to the mouths of the River Rouge, another tributary of the Detroit River, and the Ecorse River, and were 6.2 × I0^–7 and 1.7 × I0^–7 mol Sn/kg dry weight, respectively, for the top 2 cm of sediment.