ICP-AES测定铀污染土壤植物中铀的研究

采用电感耦合等离子体发射光谱(ICP-AES)对铀污染土壤植物中铀的测定方法进行了研究.在λU385.958 nm处,选择了仪器的最佳工作条件,考察了酸度和常见共存元素对测定的干扰情况,并且对比了干灰化消解和湿式消解对测定的影响.研究发现2%硝酸溶液为最佳介质,干扰离子对测定没有显著影响,干灰化消解比湿式消解得彻底.在选定条件下,方法检出限为0.18 mg·L-1,测定下限为0.61 mg·L-1,5.0000 mg·L-1的铀标准溶液的相对标准偏差RSD(n=10)为0.81%,方法回收率为96.2%～106.2%.该方法操作简单,快速.结果表明,用ICP-AES测定铀污染土壤植物样品中的铀是可行的.     

特选榨菜对铀污染土壤的修复评价

本文通过两种不同的加铀方式,加入不同种类及浓度的螯合剂,以及土壤改良剂(有机肥、微生物肥料、腐殖酸、尿素)的方法,研究了不同因素对特选榨菜修复铀污染土壤的影响。结果表明:在pH=5时把UO_2(NO_3)_2·6H_2O溶液喷洒入土壤,使土壤中铀污染浓度为100 mg·kg~(-1)时,特选榨菜地上部铀富集的浓度最大可以达到1103.42 mg·kg~(-1),根部为1909.49 mg·kg~(-1),去除率为7.81%;上述含铀土壤放置2年后制备成模拟铀污染的土壤,进而栽种特选榨菜进行修复,在100 mg·kg~(-1)铀污染浓度下,植物上部铀富集浓度最大为295.83 mg·kg~(-1),根部为268.42 mg·kg~(-1),年去除率为2.52%。用Tessier五步连续提取法测定两次修复土壤中铀的形态,发现模拟铀污染土壤比铀喷洒于土壤中有效态的铀(交换态和碳酸盐结合态)要低52.7%;加入柠檬酸、苹果酸等螯合剂以及有机肥、微生物肥料、腐殖酸、尿素等土壤改良剂,在模拟铀污染土壤修复时发现有机肥会降低植物上部对铀的富集;而柠檬酸和微生物肥会增强植物上部对铀的富集。     

铀污染土壤的植物修复研究

核工业的发展, 导致重金属铀的排放和扩散, 造成了地表土壤的污染, 对社会和环境造成了很大的影响, 如何修复被铀污染的土壤成为了一个难题, 近年发展起来的植物修复技术以其成本低廉、安全、环保的特点成为修复被铀污染的土壤的新选择. 寻找理想的超富集植物是这一技术的基础和关键之所在, 通过实验模拟铀污染土壤(土壤中铀的浓度为1.00×10² mg•kg^－1), 选取分属8种科目的19种植物去修复, 选出了几种对铀的修复性能较好的本土植物, 实验表明四季香油麦菜的生物累积系数(Bioconcentration factors, BFS)和生物转移系数(Translocation factors, TFS)都大于3, 且地上部分铀的富集浓度高达1.67×10³ mg•kg^－1, 可以作为铀的超富集植物, 四川沿阶草、四季豆、扁竹兰、吊兰几种本土植物对铀污染的土壤具有潜在的修复能力, 借助于基因工程、联合修复或添加土壤改良剂有望使其转变为对铀的超积累植物.     

镧不同施用方式对吸收差异型小白菜镉、铬吸收及生物量的影响

为探讨轻稀土La在Cd/Cr复合污染土壤种植条件下作物的生长发育效应和抗重金属胁迫生物效应,进一步为农用稀土肥料的科学施用提供借鉴。选用土壤盆栽方法和不同施肥技术(土壤混施、土壤灌施和叶面喷施),研究La对吸收差异型(低吸收累积型和高吸收累积型)小白菜Cd, Cr吸收和生物量的影响。结果表明:La不同施用方式对吸收差异型小白菜茎叶生物量的增产效应总体表现为低吸收累积型显著高于高吸收累积型,其中低吸收累积型以叶面喷施和土壤灌施处理较对照增产显著,而高吸收累积型均未表现增产效果; La不同施用方式对吸收差异型小白菜Cd, Cr吸收的抑制能力效应分别表现为Cd低吸收累积型高于高吸收累积型, Cr高吸收累积型高于低吸收累积型,其中低吸收累积型以叶面喷施和土壤灌施处理抑制Cd, Cr吸收的效应显著,而高吸收累积型抑制Cr吸收显著,抑制Cd吸收不显著或无抑制; La处理对吸收差异型小白菜Cd和Cr转运系数的降低效应变化规律与Cd和Cr抑制能力效应规律基本一致,转运系数降低效应越大,抑制重金属Cd和Cr的吸收作用越显著;外源La显著影响小白菜植株La的吸收与分布,土壤混施和土壤灌施主要以根系吸收积累为主,叶面喷施主要以茎叶吸收积累为主。表明La对Cd/Cr复合污染土壤种植作物重金属抗胁迫能力大小与作物品种重金属吸收差异和施肥技术作用机制不同有关。     

龙门山地区水系沉积物中铀含量分布特征

铀元素是具有毒性和放射性的锕系元素之一,对区域环境和人体健康具有极大的危害,开展铀元素污染评价具有重要的现实意义。以龙门山地区主要水系为主要研究对象,采集了大量的水系沉积物样品,对该地区的铀元素分布特征进行了研究。研究表明,大渡河水系沉积物中铀平均质量分数为5.50 mg/kg,绵远河水系沉积物中的铀平均质量分数为3.07 mg/kg,其余河流水系沉积物中铀含量均较低。通过龙门山地区水系沉积物中铀元素分布特征与龙门山地区矿产分布对比发现,煤矿、磷矿开发区是水系主要铀元素来源。     

多接收电感耦合等离子体质谱在单个铀颗粒物分析中的应用研究

为准确地获取单个铀颗粒物中具有核保障监督和核取证意义的铀同位素组成信息和~(230)Th/~(234)U比值,本研究基于多接收电感耦合等离子体质谱(MC-ICP-MS),建立了不同粒径铀颗粒物中铀同位素比值的测量方法和不经化学分离纯化流程的~(230)Th/~(234)U分析技术。在评估铀钍本底的基础上,采用外标法校正同位素的质量分馏效应,进样0.40 ng/g的天然铀工作溶液跳峰测量离子计数器检测效率,使用已知铀钍比例的标样校正铀钍响应差异,完成分析方法的不确定度评估。结果表明,化学处理过程引入的~(238)U和~(232)Th分别小于8×10~(-5)ng和1.5×10~(-3)ng,MC-ICP-MS对粒径0.5~5.0μm铀颗粒物中~(235)U/~(238)U测量的相对扩展不确定度3.6%(k=2),主要来自本底扣除引入的不确定度和B类不确定度;对粒径5μm铀颗粒物中~(235)U/~(238)U测量的相对扩展不确定度0.2%(k=2),主要来自法拉第杯检测器对弱信号测量的不确定度;对更大粒径铀颗粒物中~(234)U/~(235)U和~(236)U/~(235)U测量的相对扩展不确定度分别小于3.5%和3.8%(k=2),主要来自B类不确定度。不经铀钍分离纯化流程,MC-ICP-MS可测得粒径几十微米铀颗粒物中~(230)Th/~(234)U比值信息,并诊断浓缩铀颗粒物生产年龄。     

植物样品中低水平铀同位素分析

建立了一种植物样品中痕量铀同位素(~(238)U、~(235)U和~(234)U)的分析方法。通过高温灰化去除植物样品中有机质,采用混合酸消解样品灰分,应用UTEVA萃取色谱分离和纯化铀。化学分离过程中铀的回收率达94%,对Na、K、Ca等基体和干扰元素的去除率超过99%。用高灵敏度ICP-MS/MS同时测定了3种天然铀同位素含量,对~(238)U、~(235)U、~(234)U的检出限分别为3.05、0.34和0.04 pg/g,其中对~(238)U和~(235)U的检出限比文献报道值低1个数量级。对小麦粉标准参考物质中~(238)U的分析结果与参考值吻合,表明本分析方法可靠。将本方法应用于中国西安地区植物样品中铀同位素的分析,结果表明,该地区植物中铀含量和铀同位素比值处于天然水平,未发现人为铀污染。这是中国植物样品中3种天然铀同位素水平的首次调查。     

头花蓼对土壤中锑的累积特征及健康风险评价

为有效控制头花蓼重金属污染问题、保障头花蓼药用安全提供科学依据,通过盆栽试验,研究不同浓度锑(Sb)污染土壤中头花蓼(Polygonum capitatum)对Sb的吸收累积特征及头花蓼中Sb对人体的健康风险影响,并预测头花蓼食用量在人体可接受范围内时头花蓼种植土壤中Sb的安全限值。结果表明,随着土壤中Sb含量增加,头花蓼生物量及耐性系数减小,头花蓼各器官Sb含量增加,且表现为根＞叶＞茎。头花蓼根部、地上部对Sb的富集系数分别为0.53~1.76(平均1.32)、0.13~0.36(平均0.23),且均在土壤中Sb处理量为200 mg/kg时达到最大值;头花蓼对Sb的转运系数为0.13~0.24(平均0.18),表明头花蓼将Sb从根部转运到地上部的能力较低。在Sb浓度低于2.09 mg/kg的土壤中种植头花蓼,头花蓼根、茎、叶各部位均可安全食用;但土壤中Sb浓度高于8.72 mg/kg时,头花蓼各部位食用均存在安全风险。     

电感耦合等离子体质谱法测定土壤中痕量铀

建立电感耦合等离子体质谱法测定土壤样品中痕量铀含量的方法。采用硝酸、氢氟酸、高氯酸混合酸消解样品后,以铼为内标溶液校正基体干扰,用电感耦合等离子体质谱仪测定土壤中的痕量铀含量。实验结果表明,铀的质量浓度在0~20 ng/m L范围内与信号强度呈线性关系,相关系数r=0.999 9,方法检出限为0.006μg/g,测定结果的相对标准偏差小于5%(n=6),加标回收率在96%~103%之间。用该方法与标准方法对同一样品进行测定,两种方法测定结果一致。该方法准确可靠,满足土壤样品中痕量铀含量的测定要求。     

水中铀的电感耦合等离子体发射光谱法测定

建立了电感耦合等离子体发射光谱法测定水中铀的方法。优化了仪器工作条件,通过基体匹配消除了无机酸基体干扰。方法检出限为0.15 mg/L,对5.000 0 mg/L铀标准溶液测定的相对标准偏差(RSD)为0.98%(n=10),加标回收率为95%~106%,方法准确可靠。     

Cadmium Tolerance and Bioaccumulation of 18 Hemp Accessions

Hemp (Cannabis sativa L.) is a fast-growing and high biomass producing plant species, which has been traditionally grown as multiple-use crop and recently considered as an energy crop. In order to screen accessions that can be cultivated in cadmium (Cd)-contaminated soils for biodiesel production, the ability of Cd tolerance and bioaccumulation of 18 hemp cultivars or ecotypes were evaluated in pot experiment under 25?mg Cd kg(-1) (dry weight, DW) soil condition, in terms of plant growth, pigment contents, chlorophyll fluorescence, and Cd accumulation at 45?days after seedling emergence. Results showed that seedlings of all cultivars, except USO-31, Shenyang and Shengmu, could grow quite well under 25?mg Cd kg(-1) (DW) soil condition. Among them, Yunma 1, Yunma 2, Yunma 3, Yunma 4, Qujing, Longxi, Lu'an, Xingtai, and Shuyang showed great biomass (>0.5?g plant(-1)), high tolerance factors (68.6-92.3%), and little reduction of pigment content and chlorophyll fluorescence under 25?mg Cd kg(-1) (DW) soil stress, indicating these cultivars had a strong tolerance to Cd stress and could be cultivated in Cd-contaminated soils. Cultivars Longxi, Lu'an, Xingtai, Yunma 2, Yunma 3, Yunma 4, and Qujing exhibited higher Cd concentrations and total Cd in shoots. These cultivars, therefore, are good candidates for the implementation of the new strategy of cultivating biodiesel crops for phytoremediation of Cd-contaminated soils.     

Determination of thallium in soils by flame atomic absorption spectrometry

A method is described for the determination of Tl in soils by FAAS, involving extraction of Tl from 5 g of soil by digestion with HClO₄/HNO₃ followed by separation of the extracted Tl into 5 mL of diisopropylether from HBr solution, including Ce(SO₄)₂. Tl in the organic phase is determined by direct aspiration into the spectrophotometer. The percentage relative standard deviation (% RSD) for 5 replicate samples is about 1%. The detection limits (S/N = 3) of this method are 0.001 mg/L for aqueous solution and 0.02 mg/kg DW for soil, when 50 mL of soil solution corresponding to 2.5 g soil are used. The Tl concentration even of unpolluted soils can be determined. The method was shown to be unaffected by the presence of various ions in soil and was able to recover nearly 100% Tl added to soils. The arithmetic mean (range) of 18 Japanese unpolluted surface soils was 0.33 (0.10–0.56)mgTl/kg DW.     

新型手性杀虫剂唑虫酯异构体拆分及其在蔬菜中的分析方法建立

以全新手性杀虫剂唑虫酯为研究对象,通过筛选手性色谱柱和优化流动相比例,建立了唑虫酯及其氧化代谢物异构体的拆分方法,在此基础上开发利用高效液相色谱-串联质谱(HPLC-MS/MS)同时测定小白菜和蕹菜中唑虫酯及其氧化产物手性异构体的分析方法。以纤维素-三(3,5-二氯苯基氨基甲酸酯)共价键合手性柱(Chiral INC)(250 mm×4.6 mm, 5 μm)为分析柱,乙腈和2 mmol/L甲酸铵水溶液作为流动相进行梯度洗脱分离,在多反应监测负离子模式下进行检测,唑虫酯4个异构体分离度分别为1.63、2.83和1.74,唑虫酯氧化产物异构体分离度为5.82。通过衍生化的方法进一步确定出峰顺序为RS-唑虫酯、SS-唑虫酯、RR-唑虫酯、SR-唑虫酯、S-唑虫酯氧化产物和R-唑虫酯氧化产物。唑虫酯和其氧化产物的手性异构体分别在1.25~1250 μg/L和2.5~2500 μg/L范围内具有良好的线性关系,相关系数(R²)大于0.99。在蕹菜和小白菜样品中同时添加唑虫酯和唑虫酯氧化产物消旋体进行添加回收试验,添加水平为1、20、400 μg/kg(即唑虫酯异构体为0.25、5、100 μg/kg;唑虫酯氧化代谢产物异构体为0.5、10、200 μg/kg),回收率为72.6%~110.6%,相对标准偏差(RSD)均在9.4%以下,其中日内重复性的RSD在0.5%~9.4%之间;日间重复性的RSD在1.0%~8.6%之间,表明该方法具有良好的回收率和精密度。该研究可为唑虫酯这一新型手性农药的环境行为研究及后续质量控制、药效评价等提供相应的分析技术,为新农药开发应用提供有力的技术支撑。     

Leaching dynamics of uranium in a contaminated soil site

Samples from a potentially contaminated industrial area were analyzed for uranium using neutron activation analysis (NAA). Uranium concentration values had a typical uncertainty of 2 % and a detection limit of 1 Bq/kg. To investigate the potential leaching dynamics into ground water two techniques were employed. The US EPA Toxicity Characterization Leaching Procedure (TCLP) and the Sequential Extraction Procedure (SEP) were used to determine the concentration of uranium in the leachates. TCLP and SEP showed that very little of the uranium leached into solution under different chemical conditions. Values of uranium leachates ranged from 0.05 to 3.5 Bq/L; a concentration much lower than the results found in the soil concentrations which ranged from 29 to 155 Bq/kg. NAA showed an 8 % uncertainty for leachates with a detection limit of 0.13 Bq/L. To mimic environmental conditions and acid rain, pH 4.3 water was used as the extraction solvent instead of the acetic acid routinely used in TCLP. Results confirmed that very low amounts of uranium leached with values ranging from 0.0002 to 0.0122 Bq/L. These values represent 0.01–1 % of the uranium in the soil samples. The distribution of uranium in soil according to particle size was also investigated to evaluate its potential movement and possible contamination of the water table. Particles below 250 μm in diameter showed a linear increase in uranium concentration whereas those with a larger diameter had constant uranium content.     

Comparison of willow and sunflower for uranium phytoextraction induced by citric acid

This study deals with an efficiency of a low dose of citric acid soil application on phytoextraction of uranium. Willow (Salix spp.) and sunflower (Helianthus annus L.) were tested in this experiment with contaminated soil. The enhancing of uranium bioaccumulation was confirmed, but in contrast to previous studies, the highest quantity of uranium was accumulated in leaves. After 5 weeks of citric acid treatment, willow was more efficient in the uptake and translocation of uranium than sunflower. The transfer coefficient calculated for leaves increased from 0.033 (control) to 0.74, or 0.56 after five doses of 5 mmol of citric acid per 1 kg of soil for willow or sunflower, respectively. The uptake characterized by the total U content achieved 88 and 108 mg kg⁻¹ in relation to the above ground parts of sunflower and willow, respectively. Even though both plants accumulated U in their above ground parts in significant rate, they employed diverse ways to achieve it. At the end of the treatment, the physiological condition of the plants enabled us to continue this method.     

Chitosan Elicitation Impacts Flavonolignan Biosynthesis in Silybum marianum (L.) Gaertn Cell Suspension and Enhances Antioxidant and Anti-Inflammatory Activities of Cell Extracts

Silybum marianum (L.) Gaertn is a rich source of antioxidants and anti-inflammatory flavonolignans with great potential for use in pharmaceutical and cosmetic products. Its biotechnological production using in vitro culture system has been proposed. Chitosan is a well-known elicitor that strongly affects both secondary metabolites and biomass production by plants. The effect of chitosan on S. marianum cell suspension is not known yet. In the present study, suspension cultures of S. marianum were exploited for their in vitro potential to produce bioactive flavonolignans in the presence of chitosan. Established cell suspension cultures were maintained on the same hormonal media supplemented with 0.5 mg/L BAP (6-benzylaminopurine) and 1.0 mg/L NAA (α-naphthalene acetic acid) under photoperiod 16/8 h (light/dark) and exposed to various treatments of chitosan (ranging from 0.5 to 50.0 mg/L). The highest biomass production was observed for cell suspension treated with 5.0 mg/L chitosan, resulting in 123.3 ± 1.7 g/L fresh weight (FW) and 17.7 ± 0.5 g/L dry weight (DW) productions. All chitosan treatments resulted in an overall increase in the accumulation of total flavonoids (5.0 ± 0.1 mg/g DW for 5.0 mg/L chitosan), total phenolic compounds (11.0 ± 0.2 mg/g DW for 0.5 mg/L chitosan) and silymarin (9.9 ± 0.5 mg/g DW for 0.5 mg/L chitosan). In particular, higher accumulation levels of silybin B (6.3 ± 0.2 mg/g DW), silybin A (1.2 ± 0.1 mg/g DW) and silydianin (1.0 ± 0.0 mg/g DW) were recorded for 0.5 mg/L chitosan. The corresponding extracts displayed enhanced antioxidant and anti-inflammatory capacities: in particular, high ABTS antioxidant activity (741.5 ± 4.4 μM Trolox C equivalent antioxidant capacity) was recorded in extracts obtained in presence of 0.5 mg/L of chitosan, whereas highest inhibitions of cyclooxygenase 2 (COX-2, 30.5 ± 1.3 %), secretory phospholipase A2 (sPLA2, 33.9 ± 1.3 %) and 15-lipoxygenase (15-LOX-2, 31.6 ± 1.2 %) enzymes involved in inflammation process were measured in extracts obtained in the presence of 5.0 mg/L of chitosan. Taken together, these results highlight the high potential of the chitosan elicitation in the S. marianum cell suspension for enhanced production of antioxidant and anti-inflammatory silymarin-rich extracts.     

Dissipation of the plant growth regulator hexanoic acid 2-(diethylamino) ethyl ester in pakchoi and soil

A rapid and simple method for determining the plant growth regulator hexanoic acid 2-(diethylamino) ethyl ester (DA-6) in pakchoi and soil using gas chromatography-mass spectrometry (GC-MS) has been developed. For this purpose, a single step was used to extract DA-6 with dichloromethane from aqueous-acetone extracts of vegetables and soil. Average recoveries of DA-6 in pakchoi and soil were between 85% and 104% at both spiking levels 0.01 and 0.1 mg kg^?1. Relative standard deviations (RSD) were less than 11% for all of the recovery tests. The degradation of DA-6 in pakchoi and soil was studied. The results showed that DA-6 degradation in pakchoi and soil coincided with C = 3.9903 e^{?0.0516 t} , C = 0.3476 e^{?0.0224 t} , respectively; the half-lives were 13.43 h and 30.94 h in pakchoi and soil in Beijing, respectively.     

Instrumental neutron activation analysis of prehistoric and ancient bone remains

Instrumental neutron activation analysis (INAA) was used to study the element contents in bones of prehistoric dinosaurs and bones of an ancient bear and an archantrop (ancient person), which were found on the territory of Uzbekistan. Concentrations of more than 25 elements were in the range of 0.043–3600 mg/kg. Multielement analyses of bone and soil samples were carried out by INAA using the WWR-SM research nuclear reactor. Results of measurements have shown that in the dinosaurs bones the concentration of the rare earth elements (REEs) were within 280–3200 mg/kg; the uranium content reached a very high value, up to 180 mg/kg, while in soils coating the dinosaurs bones this content was 4.2 mg/kg; in the bones of the archantrop it was 1.53 mg/kg and in the bones of a standard person its amount is less than 0.016 mg/kg.     

Effects of uranium stress on physiological and biochemical characteristics in seedlings of six common edible vegetables

The large-scale exploitation of uranium (U) not only causes radioactive pollution to the soil, but also has a great adverse effect on human health. However, the current understanding of the effects of U stress on organisms is not deep enough. As food sources of human beings, vegetables can enrich U into the human body along the food chain. Therefore, the effects of soil U on seed germination, seedling growth and physiological and biochemical characteristics of six common edible vegetables (tomato, cucumber, kohlrabi, radish, cabbage, and spinach) were investigated. The results show that the toxicity of U to the six vegetables in sandy loam is cucumber?>?radish?>?spinach?>?cabbage?>?tomato?>?kohlrabi. The lower U concentration in sandy loam has certain promoting effect on seed germination and root growth. The accumulation and tolerance capacity of cucumber and radish to U in sandy loam is stronger than that of other four vegetables, which may be used as candidate species for biological treatment of U pollution. These results provide theoretical basis for clarifying the biological effects and toxicological mechanism of U pollution, and also provide theoretical basis for scientific prevention and control of soil U pollution.     

Removal of uranium anionic species from aqueous solutions by polyethylenimine–epichlorohydrin resins

The removal of uranium anionic species from aqueous solutions (initial concentration: 10–2,000 mg/L) by a low- and a high molecular weight polyethylenimine–epichlorohydrin resins was studied in the absence of background electrolytes at initial pH (pH_init) 8 to10. The amount of the sorbed U was determined spectrophotometrically using the Arsenazo III method. The maximum uptake was observed at pH_init 8 using both resins. The maximum uptake capacity observed was 221 and 388 mg U/g for the low- and high molecular weight resin respectively. The uptake data were modeled using a number of 2- and 3- parametric isotherm equations (Langmuir, Freundlich, Langmuir–Freundlich, Toth and Redlich–Peterson). The kinetics of the uranium removal was also studied and modeled using the pseudo-first and pseudo-second order equations. The surface and interior of the resin grains were examined after the sorption experiments by scanning electron microscopy/energy dispersive spectroscopy.