Trace metal levels in freshwater fish, sediment and water

The trace metal concentrations in water, sediment and aquatic organisms, such as fish, could indicate the level and tendency of the pollution. This is important not only for the protection of the environment, but for evaluation of the quality of fish meat either captured from natural waters or cultured in fishponds. The total trace metal concentrations in samples of fish from different regions of Hungary and from different species have been determined by using an X-ray fluorescence technique (EDXRF). Water, sediment and fish samples from fishpond systems with different feeding and stocking has also been analyzed. In the case of zinc contents, differences have been traced between the cultured and wild common carp. In the case of common carp reared under different feeding conditions, differences were also observed in the zinc concentration. The retention of the trace metals in the fish has been studied by measuring the levels in sediment, water and feed. The different retention can be explained by the different availability of zinc in the applied feeds, which can be related to the presence of different metal species in the feeds.     

铅蓄电池企业废气中铅及其化合物便携式XRF检测方法

在企业污染源现场实现污染物排放浓度水平的快速判定和超标风险筛查,对生态环境管理部门提高执法效率、企业提高环境管理水平意义重大。铅是一种对人体危害极大的有毒重金属,目前缺少含铅废气中铅及其化合物的便携式直读检测设备和检测方法。探索性地将X射线荧光光谱(XRF)法应用于铅蓄电池企业含铅废气中铅及其化合物的便携式快速、直读检测。研究结果表明,基于XRF的面密度法适用于铅蓄电池企业含铅废气处理设施后铅及其化合物的快速、直读检测,相对国标方法具有快速、直读、对样品无损、便于复测等特点,可用于铅及其化合物排放浓度水平的快速判定和超标风险筛查。     

Heavy metals in Jamaican surface soils

A regional survey of Jamaican surface soils has been conducted in which more than 200 samples were collected at a sample density of 1 per 64 km² across the island and analysed for total concentrations of 31 elements by instrumental neutron activation analysis (INAA), energy dispersive X-ray fluorescence (EDXRF) analysis and atomic absorption spectrophotometry (AAS). The aim of the survey was to begin the construction of a high-precision geochemical database to provide information on elemental levels in soils for application to environmental studies, agriculture, and human and animal health. Results on the regional scale are presented for As, Cd, Cu, Hg and Pb. Although Jamaican surface soils are enriched in several heavy metals compared with world soil means and crustal abundances, lead is of particular importance at this stage because of its occurrence in residential areas. Except for Cu, the distribution maps of these elements are highly correlated with bauxite which in Jamaica is associated with white limestone geology and residualterra rossa soils.     

解毒铬渣安全性研究

用扫描电镜、比表面测定仪、X-射线衍射仪测定了铬渣及解毒铬渣的表面形貌、比表面及物相组成。在模拟环境条件下对解毒铬渣进行了浸出毒性试验,结果表明,解毒铬渣在环境条件下是安全的。      

Differences in U root-to-shoot translocation between plant species explained by U distribution in roots

Accumulation and distribution of uranium in roots and shoots of four plants species differing in their cation exchange capacity of roots (CECR) was investigated. After exposure in hydroponics for seven days to 100 μmol U L⁻¹, distribution of uranium in roots was investigated through chemical extraction of roots. Higher U concentrations were measured in roots of dicots which showed a higher CECR than monocot species. Chemical extractions indicated that uranium is mostly located in the apoplasm of roots of monocots but that it is predominantly located in the symplasm of roots of dicots. Translocation of U to shoot was not significantly affected by the CECR or distribution of U between symplasm and apoplasm. Distribution of uranium in roots was investigated through chemical extraction of roots for all species. Additionally, longitudinal and radial distribution of U in roots of maize and Indian mustard, respectively showing the lowest and the highest translocation, was studied following X-ray fluorescence (XRF) analysis of specific root sections. Chemical analysis and XRF analysis of roots of maize and Indian mustard clearly indicated a higher longitudinal and radial transport of uranium in roots of Indian mustard than in roots of maize, where uranium mostly accumulated in root tips. These results showed that even if CECR could partly explain U accumulation in roots, other mechanisms like radial and longitudinal transport are implied in the translocation of U to the shoot.     

X射线荧光光谱分析空气滤膜颗粒物中多种元素

采用X射线荧光光谱分析空气滤膜采集悬浮颗粒物中的多种元素,样品不需要前处理,不使用试剂,测量1个样品中40余种元素约耗时1 h。重复测量10次NIST SRM 2783空气滤膜标准样品,多数元素的测量值与标准值基本一致,测量值的标准偏差较小;测量20个空气滤膜实际样品,并与ICP-MS法作比对,大多数元素两种方法测量结果的相对偏差较小,测量值基本一致。     

波长色散-X射线荧光光谱法测定PM2.5中23种元素

研究以单元素标准膜为基础,结合NIST SRM 2783颗粒物滤膜标准样品,建立了波长色散-X射线荧光光谱法测定PM_2.5中23种无机元素的测定方法,优化了测试条件,测量一个样品耗时约15 min,计算了各元素的方法检出限。对NIST SRM 2783滤膜标准品在一周内重复测定10次来计算方法的准确度与精密度,测定结果显示大多数元素的测量值在给出的参考值范围内,且测量标准偏差一般在10%以内。对比了石英与聚四氟乙烯材质（Teflon）滤膜的空白值,石英滤膜中Si、Fe、Na、Mg、Al、K、Ca等元素的背景值较高,Teflon滤膜的背景值较低,推荐选用Teflon滤膜作为PM_2.5组分分析采样滤膜。分别用波长色散-X射线荧光光谱法及酸消解-ICP-MS法测定了样品膜中的元素组分,得到的测定结果基本一致。     

方法标准验证实验数据中离群值的识别

对方法标准验证实验中测量数据进行合格性审核,对于后续方法精密度计算是一个重要环节。文献中识别离群值的Grubbs法、Dixon法等经典方法有时不能满足要求。探讨了用稳健统计法识别离群值的可行性。基于2套文献数据和XRF方法标准验证实验精密度测量数据,对Grubbs法、Dixon法、Mandel h检验法、质控指标法和稳健统计法(四分位法、迭代法、合格数据范围判定法)进行了比较。结果表明:稳健统计法可有效识别离群值。但四分位法存在过度"检出"现象。综合考虑多种方法识别结果有利于提高离群值判定结论的可靠性。对于个别难以判断的情形,可借助质控指标、技术要求以及数据是否剔除对实验室间标准偏差的影响进行取舍。     

Lead toxicity, defense strategies and associated indicative biomarkers in Talinum triangulare grown hydroponically

Talinum species have been used to investigate a variety of environmental problems for e.g. determination of metal pollution index and total petroleum hydrocarbons in roadside soils, stabilization and reclamation of heavy metals (HMs) in dump sites, removal of HMs from storm water-runoff and green roof leachates. Species of Talinum are popular leaf vegetables having nutrient antinutrient properties. In this study, Talinum triangulare (Jacq.) Willd (Ceylon spinach) grown hydroponically were exposed to different concentrations of lead (Pb) (0, 0.25, 0.5, 0.75, 1.0 and 1.25 mM) to investigate the biomarkers of toxicity and tolerance mechanisms. Relative water content, cell death, photosynthetic pigments, sulphoquinovosyldiacylglycerol (SQDG), anthocyanins, α-tocopherol, malondialdehyde (MDA), reactive oxygen species (ROS) glutathione (GSH and GSSG) and elemental analysis have been investigated. The results showed that Pb in roots and shoots gradually increased as the function of Pb exposure; however Pb concentration in leaves was below detectable level. Chlorophylls and SQDG contents increased at 0.25 mM of Pb treatment in comparison to control at all treated durations, thereafter decreased. Levels of carotenoid, anthocyanins, α-tocopherol, and lipid peroxidation increased in Pb treated plants compared to control. Water content, cells death and elemental analysis suggested the damage of transport system interfering with nutrient transport causing cell death. The present study also explained that Pb imposed indirect oxidative stress in leaves is characterized by decreases in GSH/GSSG ratio with increased doses of Pb treatment. Lead-induced oxidative stress was alleviated by carotenoids, anthocyanins, α-tocopherol and glutathione suggesting that these defense responses as potential biomarkers for detecting Pb toxicity.     

Accumulation, speciation and cellular localization of copper in Sesbania drummondii

Growth, accumulation and intracellular speciation and distribution of copper (Cu) in Sesbania drummondii was studied using scanning-electron microscopy (SEM), X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). The growth of seedlings was assessed in terms of biomass accumulation. The growth of the seedling was enhanced by 73.5% at a low Cu concentration (50 mg l⁻¹) compared to the control treatment. Additionally, seedling growth was inhibited by 18% at 300 mg l⁻¹ Cu with respect to the control. Copper concentration in roots and shoots was increased with increasing Cu concentration in the growth solution. The accumulation of Cu was found to be higher in roots than in the shoots. At a concentration of 300 mg l⁻¹ Cu, the roots accumulated 27,440 mg Cu kg⁻¹ dry weight (dw) while shoots accumulated 1282 mg Cu kg⁻¹ dw. Seedlings were assessed for photosynthetic activity by measuring chlorophyll a fluorescence parameters: F_v/F_m and F_v/F₀ values. Photosynthetic integrity was not affected by any of the Cu treatments. The X-ray absorption spectroscopic (XAS) studies showed that Cu was predominantly present as Cu(II) in Sesbania tissue. In addition, from the XAS studies it was shown that the Cu exists in a mixture of different coordination states consisting of Cu bound to sugars and small organic acids with some possible precipitated copper oxide. From the EXAFS studies, the coordination of Cu was determined to have four equatorial oxygen(nitrogen) ligands at 1.96 Å and two axial oxygen ligands at 2.31 Å. Scanning-electron microscopy studies revealed the distribution of Cu within the seedlings tissues, predominantly accumulated in the cortical and vascular (xylem) regions of root tissues. In the stem, most of the Cu was found within the xylem tissue. However, the deposition of Cu within the leaf tissues was in the parenchyma. The present study demonstrates the mechanisms employed by S. drummondii for Cu uptake and its biotransformation.