Dose estimation and radon action level problems due to nanosize radon progeny aerosols in underground manganese ore mine

One of the essential parameters influencing of the dose conversion factor is the ratio of unattached short-lived radon progeny. This may differ from the value identified for indoor conditions when considering special workplaces such as mines. Inevitably, application of the dose conversion factors used in surface workplaces considerably reduces the reliability of dose estimation in the case of mines.This paper surveyed the concentration of radon and its short-lived radon progeny and identified the unattached fraction of short-lived radon progeny. As well equilibrium factor during the month of August was calculated simultaneously at two extraction faces in a manganese ore mine.During working hours the average radon concentrations were 220 Bq m⁻³ and 530 Bq m⁻³ at Faces 1 and 2; the average short-lived progeny concentration was 90 Bq m⁻³ and 190 Bq m⁻³, the average equilibrium factors were 0.46 and 0.36, and the average unattached fractions were 0.21 and 0.17, respectively. The calculated dose conversion factor was between 9 and 27 mSv WLM⁻¹, but higher values could also be possible.     

Analysis of Long-term Measurements of Airborne Concentrations of Sulphur Dioxide and SO42- in the Rural United Kingdom

During the last two decades, the importance of sulphur dioxide as a pollutant has moved away from its association with suspended particulate matter, to it being a precursor of SO ₄ ^2- aerosol (acidic e.g. sulphuric acid, or neutralised e.g. ammonium sulphate). Co-located concentration data of sulphur dioxide and SO ₄ ^2- , at nine monitoring sites situated in predominantly rural areas in the United Kingdom, collected over the time period 1979–1995, have been analysed. The time series for both species are discussed for the sites. Further analysis has shown that there is a degree of correlation between sulphur dioxide and SO ₄ ^2- for most of the sites considered. This correlation is of approximately the same level for most of the sites taken independently and together, and in most cases the slopes and intercepts associated with the simple empirical model equations arising from the correlation analysis, are of the same order of magnitude. The implementation of these site-dependent model equations within dispersion models for the prediction of the concentration of airborne sulphate aerosol from knowledge of sulphur dioxide concentration is discussed. Furthermore, the correlation analysis revealed the influence of transported sulphate aerosol on the local concentration, especially during high concentration episodes.     

黄土丘陵区不同水体中氢氧同位素特征及相互关系

为了研究典型黄土丘陵区不同水体氢氧同位素特征及水体间补给转化关系,合理利用干旱半干旱区水资源,通过野外采集2019年6月至11月延安市安塞墩山周围降水、河水、地下水和土壤水样品,运用同位素示踪技术,结合混合模型探索研究区不同水体氢氧同位素特征及水循环转化关系.结果表明:河水、地下水较土壤水富集氢氧同位素;各水体D和18...     

Rural Households’ Attitude and Economic Strategies Toward the Conversion of Cropland to Forest and Grassland Program (CCFG): A Case Study in Qira,China

The Conversion of Cropland to Forest and Grassland Program (CCFG), which was initiated by the Chinese government in 1999, is a cropland retirement program with integrated objectives for ecological preservation and local development. The purpose of this article was to study the influencing factors of attitude and economic strategies in rural households toward the CCFG. Rural households’ knowledge, attitude and economic strategies toward the CCFG were investigated through a questionnaire survey in Qira, China. Influencing factors of attitude and strategies of households were analyzed using a logit model technique. The analysis indicated that household’s income level, environmental knowledge of the program, and program implementation were significant influencing factors in a household’s attitude toward the CCFG, while major influencing factors of household strategies were their regional background and availability of income generation sources. Meaningful association was not found between attitude and strategy choices. Rich households had more strategy choices, while poor households were usually confined to low input strategies with uncertain income. To sustain their livelihood, the poor need extra assistances in marketing, loan granting, employment training, information, and technical services.     

钒基活化液增活V2O5-WO3-MoO3/TiO2催化剂的实验研究

基于催化剂在线增活工艺,以火电厂运行条件下的典型钒钛类失活催化剂为原料,采用单因素变量法展开了钒基活化液各成分对失活催化剂增活效果的研究,对活化液增活后的催化剂进行活性评价及SEM、BET、FT-IR和XRD等分析,考察增活前后NO转换率、催化剂表面形貌及结构的变化情况。研究结果表明,在实验条件下,随着4种活性成分含量的增加,催化剂增活后NO转换率均呈现先升高后降低的规律,NO转换率最高达99%,且增活后催化剂表面活性成分增加,Brnsted酸性位增多,比表面积增加,对烟气具有较强适应力。     

硫酸厂SO2减排技术综述

介绍了硫酸厂优化转化工艺指标法、低温催化剂技术、尾气脱硫技术等SO2减排技术的应用进展,并探讨了各种技术的适用性。建议各硫酸厂综合考虑场地空间、投资和运行成本、脱硫副产物出路、脱硫剂来源等因素采用适用、先进的减排技术。     

简论废气氮氧化物(NO_X)浓度单位PPm与mg/m~3的换算系数关系

空气中污染物浓度的表示方法有两种,体积浓度表示法(ppm)与质量浓度表示法(mg/m3)。氮氧化物不是单一的化合物,存在多种化合物。因此目前对氮氧化物(NOX)单位换算不清,造成浓度结果计算错误。本文对这一问题作一简介。     

The use of petroleum coke as fuel in a 10 kWth chemical-looping combustor

Tests were made in a 10 kW_th chemical-looping combustor with a petroleum coke as the solid fuel and the oxygen carrier ilmenite, an iron titanium oxide. The fuel reactor is fluidized by steam and the oxygen carrier reacts with the volatiles released as well as the gasification intermediates CO and H₂. A constant fuel flow corresponding to a thermal power of 5.8 kW was introduced into the fuel reactor and a total of 11 h of operation was reached. The effects of particle circulation and carbon stripper operation on solid fuel conversion, conversion of gas from the fuel reactor and CO₂ capture were investigated. The actual CO₂ capture ranged between 60% and 75% while the solid fuel conversion was in the range of 66–78%. The low values of solid fuel conversion reflect loss of char due to low efficiency of the fuel reactor cyclone. The incomplete conversion of the gas from the fuel reactor is expressed as oxygen demand. The oxygen demand corresponds to the fraction of oxygen lacking to achieve full gas conversion and was typically 25%, due to presence of CH₄, CO and H₂ from the fuel reactor. Typical ratios of CH₄, CO and H₂ over the total gaseous carbon from the fuel reactor are respectively 5, 10 and 25%. Low loss of non-combustible fines from the system indicates very low attrition of the oxygen carrier.     

Effects of cultivation conditions on the diversity of microbes involved in the conversion of rice straw to fodder

To confirm the optimum cultivation conditions for analyzing lactic acid bacterial communities and to provide the cultivation foundation for lactic acid bacterial communities that were used to convert straw into fodder, fermented rice straw was inoculated into 13 different broths. After 48 h of cultivation, pH values, volatile products, and microbial diversity were analyzed. Except for LAB broth, the pH values of the other broths could decrease to approximately 4.5. GC/MS analysis showed that lactic acid in Tomato MRS broth, MRS broth, LAB broth, and Tomato juice broth was higher than that in the other broths. DNA concentration analysis showed that the counts of microbes in Tomato MRS broth were 2.5 times of those in other broths and that tomato juice favored the reproduction of the microbes. Denaturing gradient gel electrophoresis （DGGE） analysis showed that the number of lactic acid bacterial species in HYA broth, Tomato juice broth, and Tomato MRS broth were higher than those in the other broths.     

Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.