膜组合工艺对地下水中铀的去除及其微生物群落特征

含铀地下水因具有放射性和化学毒性对人类健康构成严重威胁,常规工艺有时无法有效去除地下水铀故需增加处理工艺以满足饮用水水质要求.以我国某地膜组合工艺处理工程为研究对象,监测了6个月运行过程中铀去除效果及常规水质参数,并对各工艺阶段出水及生物膜进行样品采集.结合水质分析与高通量测序探讨了不同工艺段出水水质参数变化,微生物群...     

Geographic Variability in Radon Exhalation at a Rehabilitated Uranium Mine in the Northern Territory, Australia

In this study, dry season radon flux densities and radon fluxes have been determined at the rehabilitated Nabarlek uranium mine in northern Australia using conventional charcoal canisters. Environmental background levels amounted to 31± 15 milli Becquerel per m² per second (mBq m⁻² s⁻¹). Radon flux densities within the fenced rehabilitated mine area showed large variations with a maximum of 6500 mBq m⁻² s⁻¹ at an area south of the former pit characterised by a disequilibrium between ²²⁶Ra and ²³⁸U. Radon flux densities were also high above the areas of the former pit (mean 971 mBq m⁻² s⁻¹) and waste rock dump (mean 335 mBq m⁻² s⁻¹). The lower limit for the total pre-mining radon flux from the fenced area (140 ha) was estimated to 214 kBq s⁻¹, post-mining radon flux amounted to 174 kBq s⁻¹.Our study highlights that the results of radon flux studies are vitally dependant on the selection of individual survey points. We suggest the use of a randomised system for both the selection of survey points and the placement of charcoal canisters at each survey point, to avoid over estimation of radon flux densities. It is also important to emphasize the significance of having reliable pre-mining radiological data available to assess the success of rehabilitation of a uranium mine site.2006 Springer. The Australian Government's right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged.     

交联壳聚糖对铀的吸附研究

以壳聚糖(CTS)为原料,在碱性条件下用环氧氯丙烷对壳聚糖进行化学改性,制得不溶水的交联壳聚糖(CCTS)。利用CCTS吸附铀(UO22+),探讨吸附动力学规律以及初始浓度,pH值的影响。实验结果表明,CCTS对UO22+的吸附符合Langmu ir吸附等温模型,并能用准二级速率方程对吸附动力学加以描述。当在CCTS为10 mg,pH为3,UO22+初始浓度为50μg/mL条件下,CCTS对UO22+的吸附去除率为98%以上。     

Bioaccumulation and biological effects in the earthworm Eisenia fetida exposed to natural and depleted uranium

The accumulations of both natural (U) and depleted (DU) uranium in the earthworms (Eisenia fetida) were studied to evaluate corresponding biological effects. Concentrations of metals in the experimental soil ranged from 1.86 to 600 mg kg⁻¹. Five biological endpoints: mortality, animals’ weight increasing, lysosomal membrane stability by measuring the neutral red retention time (the NRRT), histological changes and genetic effects (Comet assay) were used to evaluate biological effects in the earthworms after 7 and 28 days of exposure. No effects have been observed in terms of mortality or weight reduction. Cytotoxic and genetic effects were identified at quite low U concentrations. For some of these endpoints, in particular for genetic effects, the dose (U concentration)-effect relationships have been found to be non-linear. The results have also shown a statistically significant higher level of impact on the earthworms exposed to natural U compared to depleted U.     

Americium,plutonium and uranium contamination and speciation in well waters,streams and atomic lakes in the Sarzhal region of the Semipalatinsk Nuclear Test Site,Kazakhstan

New data are reported on the concentrations, isotopic composition and speciation of americium, plutonium and uranium in surface and ground waters in the Sarzhal region of the Semipalatinsk Test Site, and an adjacent area including the settlement of Sarzhal. The data relate to filtered water and suspended particulate from (a) streams originating in the Degelen Mountains, (b) the Tel′kem 1 and Tel′kem 2 atomic craters, and (c) wells on farms located within the study area and at Sarzhal. The measurements show that ²⁴¹Am, ^239,240Pu and ²³⁸U concentrations in well waters within the study area are in the range 0.04–87 mBq dm⁻³, 0.7–99 mBq dm⁻³, and 74–213 mBq dm⁻³, respectively, and for ²⁴¹Am and ^239,240Pu are elevated above the levels expected solely on the basis of global fallout. Concentrations in streams sourced in the Degelen Mountains are similar, while concentrations in the two water-filled atomic craters are somewhat higher. Suspended particulate concentrations in well waters vary considerably, though median values are very low, at 0.01 mBq dm⁻³, 0.08 mBq dm⁻³ and 0.32 mBq dm⁻³ for ²⁴¹Am, ^239,240Pu and ²³⁸U, respectively. The ²³⁵U/²³⁸U isotopic ratio in almost all well and stream waters is slightly elevated above the ‘best estimate’ value for natural uranium worldwide, suggesting that some of the uranium in these waters is of test-site provenance. Redox analysis shows that on average most of the plutonium present in the microfiltered fraction of these waters is in a chemically reduced form (mean 69%; 95% confidence interval 53–85%). In the case of the atomic craters, the proportion is even higher. As expected, all of the americium present appears to be in a reduced form. Calculations suggest that annual committed effective doses to individual adults arising from the daily ingestion of these well waters are in the range 11–42 μSv (mean 21 μSv). Presently, the ground water feeding these wells would not appear to be contaminated with radioactivity from past underground testing in the Degelen Mountains or from the Tel′kem explosions.     

华东某铀矿区稻米中放射性核素铀污染特征及健康风险评价

为查明华东某铀矿区稻米中放射性核素铀污染现状及健康风险问题,测定铀矿区和对照区共136件稻米样品中放射性核素U含量,采用单因子污染指数法评价放射性铀污染,并开展U元素健康风险评价。结果表明:(1)研究区稻米中U含量平均值为1.46 ng·g~(–1),各亚区稻米中U含量平均值从大到小顺序为:开采矿井区水冶场区含矿未采区废弃矿井区江西省背景值对照区;(2)稻米单因子污染指数为1.25,属于轻度污染。其中,开采矿井区和水冶厂区为轻度污染,废弃矿井区和对照区未受污染;(3)首次计算提出江西省大米U元素致癌风险最大斜率系数为1.04×10~3(d·kg)·mg~(–1)。各亚区稻米中成人和儿童致癌风险指数高低顺序均为:开采矿井区水冶厂区含矿未采区废弃矿井区对照区。儿童直接饮食稻米具有一定的致癌风险;开采矿井区和水冶厂区的成人存在一定致癌风险,含矿未采区和废弃矿井区以及对照区均无致癌风险。     

地浸采铀技术与工艺

地浸采铀是世界上十分先进的采矿技术，其基本原理是对可地浸砂岩型铀矿按一定网度布置工艺钻孔，从注液注孔入地浸液，使地浸液与铀进行充分反应，经铀液孔提出地表，在地表工厂进行萃取铀的过程，地浸法分为酸法和碱法两种，地浸采铀能使低品位砂岩型铀矿成为有工业价值的矿床，由于对环境污染小，已被世界大多数国家广泛采用。但是并非所有的砂岩铀矿都能地浸，只有符合地浸地质-水文评价指标的砂岩铀矿才能地浸。地浸工艺包括钻孔的布置、浸液的配制、地下水的复原和环境保护等方面。我国的地浸采铀于20世纪70年代开始探索，90年代中期开展了大规模的地浸砂岩铀找矿与开采工作，并取得了突破性进展，新疆512矿床是就是利用地浸技术评价与开采的我国第一座大型地浸铀矿山。     

粉煤灰吸附铀的影响因素探讨

为探讨粉煤灰对铀的吸附特性,考察pH、吸附时间、铀溶液浓度对吸附能力的影响,测定了吸附等温线和吸附动力学。结果表明:其吸附等温线符合Freundlich和Langmuir吸附模型,pH值是影响铀去除率的主要因素,吸附铀的最佳pH=5,铀初始浓度越高,粉煤灰的吸附量越高。实验可为地下水复原特别是采用粉煤灰渗透反应墙修复受放射性污染的地下水提供设计依据。     

Assessment of Groundwater Quality and Contamination from Uranium-Bearing Black Shale in Goesan–Boeun Areas, Korea

This study was initiated to identify the impact of metals and uranium enriched soil and black shale in groundwater quality and contamination. From a Piper diagram, groundwater was classified into four types as (Ca+Mg)–HCO₃ type, (Ca+Mg)–SO₄ type, the mixed type of these two and Na–HCO₃ type, reflecting the complicated nature of geology of the study area. Silicate weathering appeared to be the major water–rock interaction. In groundwater, metals including Cr, Pb, Cu and V, previously identified as being enriched in soils and black shale, were much lower in concentrations than Korean and US EPA drinking water guidelines. Instead, Fe and Mn caused major water-quality problems. In the artesian groundwater from an abandoned uranium mine, the uranium concentration was 21.3 µg L^–1, slightly higher than EPA guidelines of 20 µg L^–1. Heavy metals in groundwater appeared to be controlled mostly by sorptions on to Fe- and Mn-oxyhydroxides. They could be remobilised in groundwater with changes of pH and Eh conditions due to acid mine drainage from black shale or the recharge of fresh water. Uranium would be associated with carbonate and sulphate complexes in groundwater. Because of the remaining water-quality problems in the study area, we suggested containment of identified mine wastes, considering remedial measures for local problems with Fe and Mn, continuous monitoring of groundwater and developing groundwater from deep aquifers.     

Detennination of trace uranium in environment by laser induced fluorescence method

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