对新疆伴生放射性矿物开发利用中辐射安全监督管理的探讨

基于新疆富有相当数量和种类的伴生放射性煤炭、花岗石、有色金属等矿正在开发利用,必然带来一些辐射安全问题,应加强监督管理的实况,提出做好调查研究,查清伴生放射性矿的分布及辐射水平,将其纳入环境影响评价制度,制定科学性、实用性强的辐射审管标准,搞好宣传教育并全面做好监管工作等5项监管措施。     

Droplet size spectra and deposits of two aerially sprayed Bacillus thuringiensis formulations on artificial samplers and live foliage

Abstract

Two commercial formulations of Bacillus thuringiensis var. kurstaki (BTK), Foray^® 48B and Thuricide^® 48LV, were applied aerially over nine spray blocks in a hardwood forest in West Virginia in 1991. Droplet spectra and spray mass deposits were determined using water‐sensitive paper strips (WSPS), glass micro‐fiber filters (GMFFs), glass plates and castor oil. Mass deposits of BTK were also assessed on natural foliage by two bioassay methods, i.e., feeding of homogenized foliage containing a starch‐sucrose solution and force‐feeding bioassay of foliar extracts containing re‐dissolved protein precipitate. Deposits on canopy foliage and ground samplers were also assessed by total protein assay and enzyme‐linked immunosorbent assay (ELISA). Droplet spectra on the WSPS were different from those on castor oil. Droplets on horizontal ground WSPS were larger than those on vertical ground WSPS. WSPS placed at canopy level collected more droplets than those at ground level. The total protein deposits (ng/cm²) were consistently higher on all blocks than the delta‐endotoxin protein deposits. Spray mass recovery on the ground samplers were low, and ranged from 2.9 to 8.0% of the applied rates.     

Assessment of aerial spray deposits in a spruce forest using in‐flight microencapsulation technique

Abstract

Spray drops were counted and sized on Kromekote® cards at ground level, and on spruce foliage at canopy level, after aerial application of a formulation containing a microencapsulation medium, over a spruce forest in Ontario. The majority of drops (70%) on foliage was 20 ‐ 75 µm range. A coarse drop size spectrum was observed on cards with a maximum diameter (Dmax) of 380 µm, and with 85% of the drops = 130 µm in diameter. Foliar drop analysis, on the other hand, indicated a finer spectrum with a Dmax of 150 µm, and with 85% of the drops = 75 µm. These results were explained on the basis of formulation ingredients, atomizer setting, weather factors, and drop retention on target surfaces. The assessment of spray deposits on glass plates at ground level indicated that about 16% of the applied spray volume reached the forest floor, a value which is comparable to those obtained in previous forestry applications using the ultra‐low‐volume (ULV) technique.     

Reduction of dioxin emission by a multi-layer reactor with bead-shaped activated carbon in simulated gas stream and real flue gas of a sinter plant

A laboratory-scale multi-layer system was developed for the adsorption of PCDD/Fs from gas streams at various operating conditions, including gas flow rate, operating temperature and water vapor content. Excellent PCDD/F removal efficiency (>99.99%) was achieved with the multi-layer design with bead-shaped activated carbons (BACs). The PCDD/F removal efficiency achieved with the first layer adsorption bed decreased as the gas flow rate was increased due to the decrease of the gas retention time. The PCDD/F concentrations measured at the outlet of the third layer adsorption bed were all lower than 0.1 ng I-TEQ Nm⁻³. The PCDD/Fs desorbed from BAC were mainly lowly chlorinated congeners and the PCDD/F outlet concentrations increased as the operating temperature was increased. In addition, the results of pilot-scale experiment (real flue gases of an iron ore sintering plant) indicated that as the gas flow rate was controlled at 15 slpm, the removal efficiencies of PCDD/F congeners achieved with the multi-layer reactor with BAC were better than that in higher gas flow rate condition (20 slpm). Overall, the lab-scale and pilot-scale experiments indicated that PCDD/F removal achieved by multi-layer reactor with BAC strongly depended on the flow rate of the gas stream to be treated.     

Mine drainage water from the Sar Cheshmeh porphyry copper mine, Kerman, IR Iran

This paper presents the results of a study on stream and mine waters in the area of one of the world largest porphyry copper deposit located in the southeastern Iran, the Sar Cheshmeh porphyry copper mine. Trace metals are present as adsorption on Fe and Mn oxide and hydroxide particles, as sulfate, simple metal ions, and scarcely as adsorption on clay particles and hydrous aluminium oxides. Mean pH decreases and the mean concentration of trace elements, EC and increases from the maximum discharge period (MXDP) during snow melt run off (May), through the moderate discharge period (MDDP; March and July) to the minimum discharge period (MNDP; September).Water samples have sulfatic character essentially, however, from the MNDP through the MDDP towards the MXDP they show a bicarbonate tendency. This study indicates that the surface waters draining the Sar Cheshmeh open pit have a higher pH and lower concentration of trace metals compared with some other porphyry copper deposits.     

某金矿周边土壤和地下水中砷的健康风险评价

以湖北某含砷金矿污染场地为例,依据《污染场地风险评估技术导则》(HJ 25.3—2014),对其周边土壤和地下水中砷元素进行健康风险评价,结果表明:该金矿周边土壤和地下水中砷分别通过经口摄入土壤、皮肤接触土壤和吸入土壤颗粒物、饮用地下水4种暴露途径的致癌风险均超过可接受风险水平(10-6),对周边居民造成潜在危害。计算得到经口摄入、皮肤接触和吸入途径基于致癌效应的土壤风险控制值分别为1.6 mg/kg、9.3 mg/kg和12.1 mg/kg,应予以重视,并建议对矿山进行综合治理和目标值修复。     

某矿热炉烟气余热利用系统测量与诊断

对某铁合金厂2台硅铁矿热炉烟气参数进行了现场测量,测量结果表明,测点烟气温度偏低,流量偏大.通过对原始测量数据进行筛选整理,得到了更加真实的测量结果;通过分析测量数据,诊断出导致现有余热锅炉进口烟气温度偏低的主要原因,并给出相应的对策建议.     

Atmospheric emission of polychlorinated naphthalenes from iron ore sintering processes

Iron ore sintering processes constitute significant sources of dioxins, and studies have confirmed a close correlation between polychlorinated naphthalenes (PCNs) and dioxin formation. Thus, iron ore sintering processes are thought to be a potential source of PCNs, although intensive investigations on PCN emissions from sintering processes have not been carried out. Therefore, the aim of the present study was to qualify and quantify PCN emissions from nine sintering plants operating on different industrial scales. PCN concentrations ranged from 3 to 983 ng m⁻³ (0.4-23.3 pg TEQ_PCN m⁻³) and emission factors ranged from 14 to 1749 μg t⁻¹ (0.5-41.5 ng TEQ_PCN t⁻¹), with a geometric mean of 84 μg t⁻¹ (2.1 ng TEQ_PCN t⁻¹). The estimated annual emission of PCNs from sintering processes in China was 1390 mg TEQ_PCN. These figures will assist in the development of a PCN emissions inventory. Regarding emission characteristics, PCNs mainly comprised low-chlorinated homologs. The ratios of several characteristic PCN congeners were also measured and compared with those from other sources. Taken together, these results may provide useful information for identifying the sources of PCNs produced by iron ore sintering processes.     

Effect of additives in the Neem formulations on deposition,volatilization and persistence of Azadirachtin in spruce foliage

Abstract

Foliar deposits, volatilization and persistence of azadirachtin‐A (AZ‐A) were investigated after application of four spray mixes prepared from a wettable powder (WP) and three emulsifiable concentrate (EC) formulations of neem. They were applied at the dosage rate of 50 g AI in 4 L/ha onto potted spruce seedlings in a laboratory spray chamber. Droplet‐size spectra and deposits were assessed using Kromekote^® card/glass plate collection units. Foliar residues [dislodgeable residues (DR), penetrated residues (PR) and total residues (TR)] of AZ‐A and their volatilization were measured by HPLC at different intervals of time up to 60 h after treatment. Differences in the droplet‐size spectra and deposit levels were observed among the four spray mixes due to the influence of additives present in them. Dissipation half‐lives (DT₅₀) of the DR, PR and TR in the foliage were low (range, 19.5 to 38.9 h) and varied according to the residue type and the spray mix used. The DT₅₀ values of the DR were consistently lower (range, 19.5 to 31.9 h) than those of the PR (range, 30.5 to 38.9 h) due to preferential loss of the surface residues. The low DT₅₀ values observed for the DR and TR in the foliage sprayed with the WP spray mix were attributed to the particulate nature of the deposit. AZ‐A volatilized appreciably from the DR rather than from the PR. The variations found in the amounts of AZ‐A volatilized (42 to 58%) and unaccountable (38 to 46%) from the initial TR values in spruce foliage, after 60 h, were attributed to the physical form of the deposits on the target surface and the influences of additives present in the different spray mixes.