Quality of data: With special reference to the measurement of trace metals in marine samples

Our understanding of the marine environment, and the factors that influence it, depends largely on the collection and interpretation of relevant and reliable data. In this paper, the quality of data arising from measurements of trace metals in marine samples is examined in relation to the growing number of scientists involved in these measurements.     

An appraisal of pond-net samples for biological monitoring of lotic macro-invertebrates

The use of a pond-net to sample benthic macro-invertebrates is assessed as a technique for use in a national classification scheme for running water sites. In a field trial, 6 pond-net samples of 3 min duration were taken at each of 4 sites on the River Axe in south-west England. Three different people each took 2 samples at each of the sites. A comparison of the number of families and species caught indicated significant differences with respect to sites, operators and site x operator interactions. Significant inter-operator differences in the number of taxa removed from samples were also shown at the sample processing stage, but only at family level. Despite these differences, clustering and ordination procedures showed strong site faithfulness for each series of 6 samples when data were analysed at species level. Similar analyses at family level produced several misclassifications of samples with those from other sites. Most of these misclassifications were eliminated when categories of abundance were applied to the family level data. A 3 min sample collected approx. 62% of families and 50% of species that could be attained at a site by 18 min netting. The results of this field trial provided justification for the use of a pond-net as the principal sampling technique in the classification exercise.     

The interpretation of human hair trace element concentrations

Scalp hair samples collected from 86 Canadian elderly, non-institutionalized women (mean age 66.6 +/- 6.2 y) on two separate occasions ten weeks apart, were analyzed for Zn, Cu and Mn content. Fasting blood samples were also collected and serum Zn, Cu and albumin content determined. Median hair Zn, Cu and Mn and mean serum Zn and albumin concentrations were not significantly different at the pre- and post-study periods. Furthermore, hair Zn concentrations at the two sampling times were positively and significantly correlated as were hair Cu, hair Mn, serum Zn and serum albumin values. In contrast no significant correlation related the hair and serum Zn values and hair and serum Cu values at any time. The constancy of the hair Zn, Cu and Mn concentrations at the two sampling periods may reflect the homeostatic regulation which controls absorption and hence body trace element content. In addition, results indicate that, after careful laboratory washing, the effects of adventitious contamination on hair trace element content are small, and can be effectively ignored.     

Kinetics of trace metal partitioning in model anoxic marine sediments

A model anaerobic sediment consisting of humic acid, clay, ferrous sulfide, sand, and seawater was utilized to study the partitioning of Cu, Cd, Pb, and Zn between different geochemical phases. An extraction scheme was developed that was selective for each geochemical phase. Metals were dosed on one phase separately, and then mixed into the other undosed phrases. The kinetics of partitioning were rapid, regardless of which phase was initially dosed; equilibrium was reached within 2–5 days. The stoichiometry of distribution was also indepencent of the initially dosed phase. The final metal distributions showed that the metal sulfide phase was not necessarily the dominant trace metal sink in anaerobic sediments.     

Trace element content of commercial shampoos: impact on trace element levels in hair.

Popular shampoos were screened for their contents in trace elements, using ICP-MS detection in a semi-quantitative mode. Hair samples from volunteers were analyzed before and after hair washing with selected shampoos to demonstrate the effect of the contamination and the impact on occupational medicine. While some shampoos showed high levels of certain elements, the degree of contamination on the hair was found to be negligible. Only one shampoo tested, formulated with selenium sulfide, was found to seriously contaminate the hair.     

Addition of trace metals increases denitrification rate in closed marine systems

We investigated the effect of trace metals (Fe, Mn, Cu, Zn and Mo) on the denitrification unit at the Montreal Biodome. Two dosages of the five trace metals were tested on a denitrifying bacterial population which was extracted from the denitrification unit and cultured in 250 mL chemostats with artificial seawater. The low dosage showed a 20% increase in the denitrification rate whereas the high dosage had a more pronounced effect with a 250% increase. No increase in bacterial growth was observed, suggesting that the trace metals had an effect on the denitrification activity. When the trace metals were tested separately, only iron had a significant effect similar to the increase in the denitrification rate observed when the five trace metals were added. The combination of Fe and Mn caused a small but significant increase compared to the five trace metals. We then tested the effect of adding Fe, Mn and Cu to the denitrification unit at the Montreal Biodome. A high dosage of these trace metals showed a 250% increase in the denitrification rate, which went from 200 to 700 g NO(x)-N/d. Our results showed that the addition of trace metals is crucial for denitrification activities.     

Use of an in situ artificial substrate for biological accumulation and monitoring of aqueous trace metals a preliminary field investigation

A preliminary field study was undertaken to investigate the use of attached periphyton on an artificial substrate as a water column composite sampler for trace metals. Spatial and temporal trends are presented of trace metal biological accumulation terms of the substrate placement in the vicinity of a synthetic fiber chemical manufacturing plant. Seasonal distribution and biological accumulation of antimony, chromium, copper, mercury and zinc is discussed. Statistical analysis of metal accumulated as a function of substrate placement, showed significantly higher levels of chromium for the discharge station compared to the reference stations. In contrast sediment analysis of the discharge station showed only slightly higher levels of zinc and no significant chromium accumulation when compared to a upriver reference station.     

Radiotracers for the determination of the accuracy of trace element analyses

Many analytical techniques for the determination of trace elements in environmental samples are plagued by ill-defined systematic errors. Investigations of analytical techniques with radioactively labelled analytes can identify systematic errors, lead to their elimination, and can improve the accuracy of the results. Radiotracers are directly detected with high sensitivity and great rapidity in most cases by gamma-ray counters. Examples of the use of radiotracer techniques for the investigation of the following steps of analytical procedures are presented: presampling events, sampling and sample handling, mineralization of samples, separation and preconcentration, and determination. Most of the examples discussed in the text were taken from the analytical chemistry of mercury, sulfur, lead, sodium, zinc and selenium. Other examples are summarized in tables. The results of these investigations clearly show the superiority of the radiotracer technique over other techniques. A more frequent use of the radiotracer technique in investigations aimed at improving the accuracy of analytical procedures is certainly desirable.     

The variation of trace element concentration in human hair: The trace element profile in human long hair by sectional analysis using neutron activation analysis

Neutron activation analysis was used to determine the distribution of trace elements in human hair. Hair samples were obtained from five infants (two to seven years of age) with hair length ranging from 15 to 40 cm. The hairs were divided into segments, each of 2.5 cm, starting from the scalp end and trace elements were analysed in each segment. Concentrations of I, Mg, Ca and Cu increased from the scalp end to the tip. Concentrations of Cl and Br decreased inversely. Different profiles of the concentrations of Hg, Se, Ca and Mn were seen in each sample. These results were discussed with reference to the indication of environmental pollution.     

血清微量元素水平与肝癌相关性的Meta分析

目的采用Meta分析法探讨肝癌患者血清微量元素水平。方法系统检索建库以来2016年6月前有关肝癌与血清微量元素水平的文献资料,采用Rev Man5.2统计软件进行分析,Q检验和I2检验验证异质性大小,采用敏感性分析和亚组分析探讨异质性的来源,采用漏斗图法识别发表偏倚。结果共纳入文献14篇,肝癌组636例,对照组851例,血清铜、锌、铁水平合并标准化均数差和95%可信区间分别为(1.65,1.28~2.03)、(-1.52,-2.14~-0.91)、(-1.21,-1.79~-0.63),差异有统计学意义(Z分别为8.69、4.85、2.70,P<0.001),Mn、Mg水平在两组间差异无统计学意义(P>0.05)。结论肝癌患者存在微量元素异常,血清Cu升高,血清Zn、Fe降低,Mn、Mg表现为不平衡状态,说明肝癌与微量元素水平有关,有必要开展更广泛和深入的微量元素研究。     

分离痕迹物证在汽车火灾调查中的应用

以一起车辆火灾事故的调查为例,以火灾现场勘验为重点,利用分离痕迹物证,分析火灾发生的条件,认定了火灾原因,并对火灾现场勘验提出建议.     

Trace element carriers in combined sewer during dry and wet weather: an electron microscope investigation

The nature of trace element carriers contained in sewage and combined sewer overflow (CSO) was investigated by TEM-EDX-Electron diffraction and SEM-EDX. During dry weather, chalcophile elements were found to accumulate in sewer sediments as early diagenetic sulfide phases. The sulfurization of some metal alloys was also evidenced. Other heavy metal carriers detected in sewage include metal alloys, some iron oxihydroxide phases and neoformed phosphate minerals such as anapaite. During rain events, the detailed characterization of individual mineral species allowed to differentiate the contributions from various specific sources. Metal plating particles, barite from automobile brake, or rare earth oxides from catalytic exhaust pipes, originate from road runoff, whereas PbSn alloys and lead carbonates are attributed to zinc-works from roofs and paint from building siding. Soil contribution can be traced by the presence of clay minerals, iron oxihydroxides, zircons and rare earth phosphates. However, the most abundant heavy metal carriers in CSO samples were the sulfide particles eroded from sewer sediments. The evolution of relative abundances of trace element carriers during a single storm event, suggests that the pollution due to the "first flush" effect principally results from the sewer stock of sulfides and previously deposited metal alloys, rather than from urban surface runoff.     

An experimental investigation of blade element theory for wind turbines. Part 1. Mean flow results

This paper describes an investigation of blade element theory, which is commonly used to describe the flow through wind turbine blades. A two-bladed model turbine was shrouded by a constant-diameter pipe. The tip clearance was sufficiently small to minimise and localise the tip clearance losses. By passively heating the wake of one of the turbine supports, it was found that supports did not produce any significant circumferential non-uniformity in the mean axial and circumferential velocities. These velocities were measured using a conventional three-hole yawmeter and an X-probe hot-wire anemometer. The agreement between the two methods was good. The turbine's power output was also determined by two independent methods; again with good agreement. The major finding was that blade element theory underestimated the power contribution as a function of radius wherever the local angle of attack exceeded the angle that gives the maximum lift/drag in two-dimensional flow. Several possible causes of the discrepancy are discussed.     

浅谈玻璃破坏痕迹在火场勘察中的证明作用

通过对火场中玻璃的不同破坏痕迹的原因研究,进而解释这些破坏痕迹在火场中所能够起到的证明作用。     

陶瓷地理标志产品微量元素迁移量检测研究

利用电感耦合等离子体质谱仪对20种陶瓷地理标志产品中的砷、镉、铬、镍、铅、锑、锌、铜、锰等9种微量元素迁移量情况进行检测。结果显示,镉、铬、锑在20种地理标志产品陶瓷中均未检出;铅、锌、铜、锰迁移量在有釉瓷（陶）器的多数种类中检出,其中锌迁移量突出;砷、镍迁移量在无釉陶器中检出。     

Experimental investigation of engine emissions with marine gas oil-oxygenate blends

This paper investigates the diesel engine performance and exhaust emissions with marine gas oil-alternative fuel additive. Marine gas oil (MGO) was selected as base fuel for the engine experiments. An oxygenate, diethylene glycol dimethyl ether (DGM), and a biodiesel (BD) jatropha oil methyl ester (JOME) with a volume of 10% were blended with the MGO fuel. JOME was derived from inedible jatropha oil. Lower emissions with diesel-BD blends (soybean methyl ester, rapeseed methyl ester etc.) have been established so far, but the effect of MGO-BD (JOME) blends on engine performance and emissions has been a growing interest as JOME (BD) is derived from inedible oil and MGO is frequently used in maritime transports. No phase separation between MGO-DGM and MGO-JOME blends was found. The neat MGO, MGO-DGM and MGO-JOME blends are termed as MGO, Ox10 and B10 respectively. The experiments were conducted with a six-cylinder, four-stroke, turbocharged, direct-injection Scania DC 1102 (DI) diesel engine. The experimental results showed significant reductions in fine particle number and mass emissions, PM and smoke emissions with Ox10 and B10 fuels compared to the MGO fuel. Other emissions including total unburned hydrocarbon (THC), carbon monoxide (CO) and engine noise were also reduced with the Ox10 and B10 fuels, while maintaining similar brake specific fuel consumption (BSFC) and thermal efficiency with MGO fuel. Oxides of nitrogen (NOx) emissions, on the other hand, were slightly higher with the Ox10 and B10 fuels at high engine load conditions.     

Enhanced methods for assessment of the trace element composition of Iron Age bone

Modern, ultra-trace, analytical methods, coupled with magnetic sector ICP-MS (HR-ICP-MS), were applied to the determination of a large suite of major and trace elements in Iron Age bones. The high sensitivity and un-paralleled signal-to-noise characteristics of HR-ICP-MS enabled the accurate measurement of Ag, Al, As, Ba, Ca, Cd, Ce, Co, Cr, Cu, Fe, La, Li, Mg, Mn, Ni, P, Pb, Pt, Rb, Sr, U, V, and Zn in small bone sections (<75 mg). Critically, the HR-ICP-MS effectively addressed molecular interferences, which would likely have compromised data generated with quadrupole-based ICP-MS instruments. Contamination and diagenetic alteration of ancient bone are grave concerns, which if not properly addressed, may result in serious misinterpretation of data from bone archives. Analytical procedures and several chemical and statistical methods (Principal Components Analysis - PCA) were studied to assess their utility in identifying and correcting bone contamination and diagenetic alteration. Uncertainties in bone (femur) sampling were characterized for each element and longitudinal variation was found to be the dominant source of sampling variability. However the longitudinal variation in most trace elements levels was relatively modest, ranging between 9 and 17% RSD. Bone surface contamination was evaluated using sequential acid leaching. Calcium-normalized metal levels in brief, timed, dilute nitric acid leaches were compared with similarly normalized interior core metal levels to assess the degree of surface enrichment. A select group of metals (Mn, Co, Ni, Ag, Cd, and Pt) were observed to be enriched by up to a factor of 10 in the bone surface, indicating that that these elements may have a higher contamination component. However, the results of sequential acid leaching experiments indicated that the single acid leaching step was effective in removing most surface-enriched contaminants. While the leaching protocol was effective in removing contaminants associated with the bone surface, there remained potentially significant residual levels of soil-sourced contaminant tracers within the leached bone. To address this issue a mathematical procedure, based on metal/aluminum ratios, was developed to correct-for the soil-contaminant metal pools. Soil correction fractions for the primary anthropogenically mobilized metals evaluated were greatest for Pb (13.6%) followed by As (4.4%), Ag (3.9%), and Cd (0.94%). Although median soil corrections were typically low, many samples did require a much larger correction, thus both bone cleaning and soil corrections may be necessary to realize accurate endogenous bone elemental data. The results of the PCA analysis were remarkably consistent with outcomes from the chemical and elemental ratio protocols evaluated in the study, and suggest that loadings on certain factors will be helpful in screening for soil-biased samples and in identifying diagenetically altered bone. Application of these contamination evaluation and correction tools was made possible by the high-quality, multi-element, datasets produced by HR-ICP-MS. Large variations in bone core concentrations between the 80 Iron Age specimens examined were observed for all the primary trace elements and in many of the supporting elements, even after correction for major contaminant components.     

Natural ventilation of indoor spaces while minimizing heat losses: Theoretical and experimental investigation

Limiting heat losses during ventilation of indoor building spaces has become a basic aim for architects, particularly since the oil crisis of 1970. Much experience has been gained in terms of ventilation of indoor spaces. Nevertheless, due to the complex applications, attempts to create a theoretical base for solving the problems related to the issue are limited, especially determining the minimum ventilation period required within a designated space. In this paper we have approached this matter, both theoretically and experimentally. The conclusion we reached was that controlled ventilation of spaces through vent holes that successively open and close at regular time intervals can limit the excessive circulation of air masses, which in turn limits heat losses.     

Correlation between sub-micron surface roughness of iron oxide encrustations and trace element concentrations

Iron oxide encrustations are formed on black slate surfaces during oxidative weathering of iron sulfide and phosphate bearing, organic matter-rich slates. Synchronously, trace elements are released during ongoing weathering. Laser ablation ICP-MS analyses of a weathered and encrusted slate showed that major portions of the V, Cu, As, Mo, Pb, Th, and U reside in the encrustation.Recently a potential relationship between several micrometer to 500 nm surface topography roughness of such encrustations and its uranium concentration was shown. Based on laser scanning microscopy measurements, the present study shows that this interrelation must be expanded to small submicron-sized half-pores with diameters between 100 nm and 500 nm. We demonstrate that the relationship is not limited to topography variations of a single encrustation in the hand-specimen scale. Surface topography and geochemical analyses of iron oxide encrustations from several locations but from the same geochemical environment and with similar weathering history showed that the concentrations of U, P, Cu, and Zn correlate inversely with the surface roughness parameter F. This parameter represents the total surface area and is - in this case - a proxy for the root-mean square surface roughness Rq.This study substantiates the environmental importance that micrometer- to submicrometer topography variations of fluid-rock interfaces govern the trapping of trace elements.