Plant Uptake of Trace Metal Oxoions From Two Contrasting Acid Soils

Uptake of arsenic, molybdenum, uranium and vanadium by species of natural vegetation (Agrostis capillaris, Betula pendula, Calluna vulgaris, and Deschampsia flexuosa) on two contrasting, highly acid soils (pH of soil solution 4.2-4.3), differing in natural abundance of these elements, was compared. the soil developed from alum shale was rich in these elements, the soil from a gneiss moraine was poor in these elements. Leaf/ above ground biomass concentrations were positively related to soil concentrations of the elements, but least closely for uranium, and vanadium tended to be excluded by the plants, compared to arsenic, and especially to molybdenum. the relationships between soil and plant concentrations were broadly similar whether nitric acid-digestible or the much lower DTPA extractable soil fractions were considered. Leaf concentrations of plants from the shale and the gneiss soil, respectively, ranged 1.41-2.76 and 0.30-0.58 nmolg^-1 dry weight for arsenic, 14-140 and 0.5-9.6 for molybdenum, 0.031-0.069 and 0.013-0.030 for uranium, 2.3-6.4 and 0.75-3.3 for vanadium.     

铀尾矿中不同形态铀释放的影响因素及其相关性

采用正交试验、连续提取法及主成分分析,研究了液固比、浸出时间、酸雨pH值、PO₄^3-、CO₃^2-、Ca²⁺和腐殖酸浓度对铀尾矿库内铀尾矿中不同形态铀释放的影响.结果表明：影响易迁移态铀释放的因素,按重要程度排序为：Ca²⁺>酸雨pH值>CO₃^2->腐殖酸>浸出时间>PO₄^3->液固比,前4个因素是主要影响因素,且CO₃^2-与酸雨pH值的相关性最强.影响潜在迁移态铀释放的因素,按重要程度排序为：Ca²⁺>液固比>浸出时间>CO₃^2->腐殖酸>酸雨pH值>PO₄^3-,前4个因素是主要影响因素,且PO₄^3-与酸雨pH值的相关性最强.影响稳定态铀释放的因素,按重要程度排序为：PO₄^3->腐殖酸>CO₃^2->酸雨pH值>液固比>Ca²⁺>浸出时间,前4个因素是主要影响因素,且PO₄^3-与CO₃^2-的相关性最强.     

Potentiometric techniques applied to the modelling of actinide migration in natural water systems†

The utility of potentiometric techniques applied to environmental problems is discussed. The applicability of this technique to the estimation of thermodynamic quantities important for the modelling of uranium migration in natural waters is demonstrated. An experimental methodology for the determination of the UO₂(s) solubility product and the UO²⁺/U⁴⁺ redox potentials is proposed.     

改性羧甲基纤维素对铀吸附机理的试验研究

对羧甲基纤维素(CMC)进行改性,并将其用于吸附废水中的铀.研究结果表明:在温度为70℃~80℃、单体质量浓度为30%~35%、羧甲基纤维素:丙烯酸(质量比)为10:2.5、反应时间为3.5~4h条件下,CMC改性效果最好;在改性CMC质量浓度为0.10g/L,温度为25℃, pH值为5.0,反应时间60min的条件下,对废水中铀去除率达到了97.1%;改性CMC对溶液中U(VI)的吸附过程符合Freundlich方程,其吸附动力学数据符合准一级方程(R2=0.9618),表明改性CMC的吸附主要是表面吸附;热力学研究表明,改性CMC对铀的吸附吉布斯自由能(ΔG0)0,吸附过程是自发的吸热反应、以物理吸附为主的过程.     

Soil characteristics influence the radionuclide uptake of different plant species

The key point of food plant agriculture is how to regulate the harmonious relationship between the soil and the plant environment. This study deals with radionuclide uptake by two food plant and two fruit tree species in relation to the geochemical characteristics of the soil. Uranium and thorium content was determined in coastal black sand and inland cultivated soils. Four commonly cultivated species Eruca sativa, Lycopersicon esculentum, Psidium guajava and Mangifera indica were investigated. Physical and chemical properties of the soil were analysed in relation to uranium and thorium uptake by plants. The results revealed the ability of plants to accumulate uranium and thorium in their edible portions. The absorbed radionuclides were positively correlated with their concentrations in the soil and the geochemical characteristics of the soil. The transfer of radioactive elements from soil to plant is a complex process that can be regulated by controlling the geochemical characteristics of the soil, including pH, clay, silt and organic matter content that reduce the bioavailability of soil radionuclides to plants, and in turn reduce the risks of biota and human exposure to radionuclide contamination.     

华南某铀矿开采利用对地表水环境质量的影响

以广东省某铀矿区为研究对象,利用电感耦合等离子体发射光谱仪(ICP-OES)测定了矿山、水冶厂及其周边地表水体共42个水样(包括工业废水、池塘水、溪流水、河水和矿区饮用水)中放射性元素(U和Th)和其它一些金属元素(Fe、Mn、Mg、Cu、Zn、Co、Ni、Li、Ca、Na、K、Al、Sr和Ba)的含量.由此确认铀矿区产生高污废水的重要环节和关键污染元素,并了解这些元素的迁移变化规律以及对周边地表水产生的影响.结果表明:(1)铀矿区产生高污外排废水的主要生产环节是采矿、铀矿堆浸和尾矿露天堆积,排放废水中U和Mn含量分别为0.238—8.700 mg.L-1和0.62—94.23 mg.L-1,均高于国家工业废水允许排放标准(GBJ8—74和GB8978—1996)的限定值;(2)铀矿周边用作当地农业灌溉和露天水源的溪流由于受纳了矿区外排废水,明显受到了U和Mn的污染:U含量在枯水期和丰水期分别为(0.415±0.619)mg.L-1和(0.233±0.308)mg.L-1,Mn含量在枯水期和丰水期分别为(8.72±12.8)mg.L-1和(8.56±12.61)mg.L-1;(3)受纳溪流中U、Fe的含量枯水期高于丰水期,而Mn和Cu的含量基本保持不变,且大多数元素的含量随着迁移距离的增加在枯水期和丰水期均呈下降趋势,指示污染源来自铀矿区;(4)铀矿区生产活动引起的地表水污染目前仅局限于铀矿区和周边较小的区域,但仍应引起重视.     

Environmental justice: A louisiana case study

The paper begins with a brief analysis of the concepts of environmental justice and environmental racism and classism. The authors argue that pollution- and environment-related decision-making is prima facie wrong whenever it results in inequitable treatment of individuals on the basis of race or socio-economic status. The essay next surveys the history of the doctrine of free informed consent and argues that the consent of those affected is necessary for ensuring the fairness of decision-making for siting hazardous facilities. The paper also points out that equal opportunity to environmental protection and free informed consent are important rights. Finally, it presents a case study on the proposed uranium enrichment facility near Homer, Louisiana and argues that siting the plant would violate norms of distributive equity and free informed consent. It concludes that siting the facility is a case of environmental injustice and likely an example of environmental racism or classism.     

生物吸附法处理含铀废水研究进展

生物吸附法处理含铀废水是新兴的研究领域。本文介绍了吸附铀的生物材料的来源以及影响吸附过程的各种因素，总结了生物吸附的机理、生物材料的改性和固定化、生物吸附的数学模型等方面的研究进展。     

云南某铀矿采冶场退役后对周围辐射环境影响水平调查

对云南某铀矿退役采冶场周围辐射环境影响情况进行调查分析,结果显示:整个区域呈部分面源和点源污染,重点区域没有被污染,饮用水源地、生产用水等测值均在该地区土壤中、水中天然放射性核素含量范围内。但是该村村民打算用铀矿采冶场遗留下来的渣场作为居民生活垃圾填埋场是不可行的。     

低剂量浓缩铀对脾淋巴细胞DNA合成和UDS效应

研究机体摄入浓缩铀²³⁵UO₂F₂时,对外周免疫器官脾淋巴细胞DNA合成和UDS的影响。观察发现,当摄入低剂量浓缩铀0.1μg/kg体重时,可刺激T淋巴细胞的转化增殖,刺激指数增升。低剂量位缩铀摄入水平在0.1～20μg/kg体重时,可使紫外线诱导的脾淋巴细胞UDS呈现明显刺激效应,增强对脾淋巴细胞DNA切除修复能力。当浓缩铀内污染水平进一步加大时,可使脾T、B淋巴细胞的DNA合成以及UDS都呈现明显抑制。