Abiotic resource depletion potentials (ADPs) for elements revisited—updating ultimate reserve estimates and introducing time series for production data

Purpose

In 1995, the original method for assessing the impact category abiotic resource depletion using abiotic depletion potentials (ADPs) was published. The ADP of a resource was defined as the ratio of the annual production and the square of the ultimate (crustal content based) reserve for the resource divided by the same ratio for a reference resource (antimony (Sb)). In 2002, ADPs were updated based on the most recent USGS annual production data. In addition, the impact category was sub-divided into two categories, using two sets of ADPs: the ADP for fossil fuels and the ADP for elements; in this article, we focus on the ADP for elements. Since then, ADP values have not been updated anymore despite the availability of updates of annual production data and also updates of crustal content data that constitute the basis of the ultimate reserves. Moreover, it was known that the coverage of elements by ADPs was incomplete. These three aspects together can affect relative ranking of abiotic resources based on the ADP. Furthermore, dealing with annually changing production data might have to be revisited by proposing new calculation procedures. Finally, category totals to calculate normalized indicator results have to be updated as well, because incomplete coverage of elements can lead to biased results.

Methods

We used updated reserve estimates and time series of production data from authoritative sources to calculate ADPs for different years. We also explored the use of several variations: moving averages and cumulative production data. We analyzed the patterns in ADP over time and the contribution by different elements in the category total. Furthermore, two case studies are carried out applying two different normalization reference areas (the EU 27 as normalization reference area and the world) for 2010.

Results and discussion

We present the results of the data updates and improved coverage. On top of this, new calculation procedures are proposed for ADPs, dealing with the annually changing production data. The case studies show that the improvements of data and calculation procedures will change the normalized indicator results of many case studies considerably, making ADP less sensitive for fluctuating production data in the future.

Conclusions

The update of ultimate reserve and production data and the revision of calculation procedures of ADPs and category totals have resulted in an improved, up-to-date, and more complete set of ADPs and a category total that better reflects the total resource depletion magnitude than before. An ADP based on the cumulative production overall years is most in line with the intent of the original ADP method. We further recommend to only use category totals based on production data for the same year as is used for the other (emission-based) impact categories.

     

Instrumental neutron activation analysis of Standard Reference Material 1941, Organics in Marine Sediment

The National Institute of Standards and Technology has developed a new Standard Reference Material 1941, “Organics in Marine Sediment.” In addition to the organic constituents, over 30 elements have been determined by instrumental neutron activation analysis and prompt-gamma activation analysis. The homogeneity of the material was investigated and relative standard deviations of single-element concentrations in 250-mg samples were found to be 1% or less with regard to major inorganic constituents and rare earth elements. A slightly higher relative SD was found for elements that may stem from biological or anthropogenic input. The element concentrations determined in this work are discussed in comparison to concentrations in other similar reference materials. Concentrations for 31 elements will be included for information on the certificate.

     

A fast method for multi-metal determination in soil samples by high-resolution inductively-coupled plasma-mass spectrometry (HR–ICP–MS)

Abstract

Methods for multi-elemental quantitative analysis of soil samples by high-resolution inductively-coupled plasma-mass spectrometry (HR–ICP–MS) with preceding one-step wet digestion in a high-pressure microwave system have been developed. The application of aqua regia as a reagent for wet digestion using a high-pressure microwave digestion system, followed by determination using HR–ICP–MS, allows an accurate, simultaneous determination of a large number of heavy metals and metalloids that are considered as potentially hazardous for the environment and health. The values of the concentrations of the elements in the analysed certified reference material (CRM) that have been obtained in this study can be used as indicative values where this CRM is used as a control for the quality of the measurements.     

Investigation of Metal levels in Artemisia herba-alba Medicinal Plant and Soil Samples Collected from Different Areas in Jordan Country

ABSTRACT

The concentrations of selected heavy metals including cadmium (Cd), lead (Pb), zinc (Zn), copper (Cu), nickel (Ni) and iron (Fe) in stems and leaves of Artemisia herba-alba medicinal plant and soil samples were evaluated. Results showed that there in heavy metal concentrations of washed and unwashed parts of A. herba-alba from northern site (Irbid), Middle site (Al-Mafraq), and Souhern site (Ma’an) (P < .05). Moreover, the results of this study revealed that there is a correlation between heavy metal levels in medicinal plants and their concentrations in soil. Two standard reference materials of plant (SRM 1790a; spinach, CRM 281; ryegrass) and a standard reference material of soil (GBW 07406) were examined to validate the method used. There were good agreements between the measured values of these standard reference materials and their certified values. In addition to that high recoveries for tested elements were ranged between 91.7–97.7%, 90–96.6%, and 92.2–97.7% in (CRM281, ryegrass), (SRM1570a, spinach) and (GBW 04706, soil) respectively. It is reasonable to conclude that the variation in metal concentration from site to another site as well as from element to another element may be due to the different factors such as traf?c volumes, the wind directions, the soil nature, and the element behavior.

Based on the results obtained, the health authorities will take in consideration these useful information and direct the residents about the risk of these pollutants.     

Instrumental neutron activation analysis of biological samples

The elemental compositions of 18 biological reference materials have been processed, for 14 stepped combinations of irradiation/decay/counting times, by the INAA Advance Prediction Computer Program. The 18 materials studied include 11 plant materials, 5 animal materials, and 2 other biological materials. Of these 18 materials, 14 are NBS Standard Reference Materials and four are IAEA reference materials. Overall, the results show that a mean of 52% of the input elements can be determined to a relative standard deviation of ±10% or better by reactor flux (thermal plus epithermal) INAA.

     

Determination of reference ranges for elements in human scalp hair

Expected values, reference ranges, or reference limits are necessary to enable clinicians to apply analytical chemical data in the delivery of health care. Determination of references ranges is not straightforward in terms of either selecting a reference population or performing statistical analysis. In light of logistical, scientific, and economic obstacles, it is understandable that clinical laboratories often combine approaches in developing health associated reference values. A laboratory may choose to:

Environmental benchmarks for buildings: a critical literature review

Purpose

To reduce the environmental impact of the building sector, environmental targets considering the full life cycle of buildings can be supportive. In recent years, various benchmarks based on Life Cycle Assessment (LCA) have been developed as part of regulations, labelling systems, sustainability rating tools and research studies. The objective of this paper is to critically analyse 23 existing benchmarking systems focusing on the benchmark methodology but also on the benchmark applications and communication.

Methods

The critical literature review consists of two parts. In a first part, the choices related to the assessment method, functional equivalent, definition of benchmark values, benchmark scope, benchmark applications and benchmark communication are compared. In the second part, benchmark values are compiled from literature and statistically analysed.

Results and discussion

The comparative analysis allows to identify the main approaches and methods used in benchmarking systems. For each evaluation aspect, the strengths and weaknesses of the various approaches are highlighted. The statistical analysis provides insight in the spread of benchmark values. Important variations are found between the literature sources which can be explained by differences in benchmark approach, scope, system boundaries and applications.

Conclusions

Based on the comparative analysis, recommendations are formulated for the development of LCA benchmarks for the building sector. The results of the statistical analysis furthermore provide reference values which can be used for the validation of future benchmarks. For global warming, the statistical values for the full life cycle impacts (i.e. embodied and operational impacts) range from about 15 up to 35 kg CO₂ eq/m².a.

     

Assessment of Trace Elements in Scalp Hair of a Young Urban Population in Brazil

The aim of this study was to establish background values for toxic and essential elements in hair, interelement correlations and the differences in levels between genders in a healthy young population from Southern Brazil. Hair samples (n = 167) were collected from healthy students aged 12–18 years. Trace element concentrations in hair were determined by inductively coupled plasma mass spectrometry. The study provided relatively low values for toxic elements and balanced concentrations for the essential elements in the adolescents' hair with reliable reference data. Interestingly, this study also demonstrated statistical correlations considered newfound between the elements in hair. Hair mercury levels were influenced by gender; with males presenting higher values. The overall findings of the present study, with respect to the estimated chemical elements, are of prime importance in the evaluation of reference values for determining environmental effects on children living in urban areas.     

Dietary Exposure Assessment of Potentially Toxic Trace Elements in Fruits and Vegetables Sold in Town of Kapan,Armenia

Fruits and vegetables grown under the impact of Armenia’s mining industry are widely sold in markets of adjacent towns. As the share of fruits and vegetables in Armenians’ diet is significant, the present study aims to assess the dietary exposure of potentially toxic trace elements through the intake of fruits and vegetables sold in Kapan town, located in the biggest mining region of Armenia. The concentrations of Cu, Mo, Ni, Cr, Pb, Zn, Hg, As, and Cd in 15 types of fruits and vegetables were determined. Non-carcinogenic and carcinogenic risks were assessed. Although the estimated daily intakes of trace elements for each studied food item did not exceed health-based guidelines values, in case of the combined consumption of fruits and vegetables estimated cumulative daily intakes exceeded reference doses for Cu and Mo. Moreover, carcinogenic risk for the majority of fruits and vegetables exceeded the EPA recommended risk level of 10⁻⁶, indicating adverse health effect to local population. The outcomes of this study can serve as a basis for further research that will consider many other exposure pathways (i.e., inhalation or dermal pathways) in order to ensure the safety of the residents living under the impact of mining industry.

     

Expressed Repeat Elements Improve RT-qPCR Normalization across a Wide Range of Zebrafish Gene Expression Studies

The selection and validation of stably expressed reference genes is a critical issue for proper RT-qPCR data normalization. In zebrafish expression studies, many commonly used reference genes are not generally applicable given their variability in expression levels under a variety of experimental conditions. Inappropriate use of these reference genes may lead to false interpretation of expression data and unreliable conclusions. In this study, we evaluated a novel normalization method in zebrafish using expressed repetitive elements (ERE) as reference targets, instead of specific protein coding mRNA targets. We assessed and compared the expression stability of a number of EREs to that of commonly used zebrafish reference genes in a diverse set of experimental conditions including a developmental time series, a set of different organs from adult fish and different treatments of zebrafish embryos including morpholino injections and administration of chemicals. Using geNorm and rank aggregation analysis we demonstrated that EREs have a higher overall expression stability compared to the commonly used reference genes. Moreover, we propose a limited set of ERE reference targets (hatn10, dna15ta1 and loopern4), that show stable expression throughout the wide range of experiments in this study, as strong candidates for inclusion as reference targets for qPCR normalization in future zebrafish expression studies. Our applied strategy to find and evaluate candidate expressed repeat elements for RT-qPCR data normalization has high potential to be used also for other species.     

Investigating the limits of sensory discrimination

Abstract

There are two extant theories concerning the limits of sensory discrimination. This article refers briefly to the history, physiological background, and adaptive implications of the two theories, but is mainly concerned with describing an experiment, suitable for colleges and sixth-forms, which can be used to investigate the validity of the two theories.

Details of experimental procedure are presented and discussed with reference to the analysis, limitations, and use of the experiment.     

Is the bioavailability index applicable for trace elements in different types of soil?

Abstract

The bioavailability index (BI) is defined as the proportion of reduction in a plant’s accumulation of an element, caused by the removal of the extractable fraction of the element of interest from the soil. The BI and corresponding experimental methods were quantitatively applied to evaluate the bioavailability of trace elements in five Chinese soils. The soil was first extracted with various reagents (DTPA, HCl and NH₂OH.HCI) separately, to remove the extractable elements. The soil, after extraction, was washed with deionised water to eliminate the extractant used in the fractionation analysis. Then the pH of the soil was re-adjusted with CaO. The soil was then fertilised and incubated in a greenhouse for four weeks. Tests showed that after incubation the pH, cation exchange capacity (CEC) and organic matter (OM) of the treated soil were close to their original values. Wheat (Triticum aestivum L.) was planted in both the untreated and treated soil for eight weeks. After harvest the plant concentrations of the elements Cr, Mn, Co, Ni, Zn, Cu, Cd, and Pb were analysed by inductively coupled plasma mass spectrometry (ICPMS). Trace element accumulation by plants grown in the treated soil was reduced significantly compared with that of plants grown in the untreated soil. The results showed that BI values were in the order BI(DTPA)>BI(HCl)>BI(NH₂OH.HCl). This indicated that the DTPA-extractable fraction represented a highly available fraction of the total content. Variations of BI among different trace elements show that Cr, Mn, Zn and Co have a higher BI, in general for the elements tested, whereas, Cu, Cd and Pb have lower values. There are also slight differences in the BI among soils. However, no significant relationship could be found between the BI and the soil characteristics.     

Problems of being a cell in a soft body

Many soft bodied coelenterates are highly deformable or contractile. In the absence of hard skeletal elements, the epithelia are subjected to mechanical forces which cause a wide range of structural changes in the component epithelial cells. What kinds of structural change occur and how are the cells adapted to them? These questions are addressed with reference to cell surface area, cell membranes, cell junctions and epithelial cilia.

     

An evaluation of chemical shift index-based secondary structure determination in proteins: Influence of random coil chemical shifts

Random coil chemical shifts are commonly used to detect protein secondary structural elements in chemical shift index (CSI) calculations. Though this technique is widely used and seems reliable for folded proteins, the choice of reference random coil chemical shift values can significantly alter the outcome of secondary structure estimation. In order to evaluate these effects, we present a comparison of secondary structure content calculated using CSI, based on five different reference random coil chemical shift value sets, to that derived from three-dimensional structures.Our results show that none of the reference random coil data sets chosen for evaluation fully reproduces the actual secondary structures. Among the reference values generally available to date, most tend to be good estimators only of helices. Based on our evaluation, we recommend the experimental values measured by Schwarzinger et al.(2000), and statistical values obtained by Lukin et al. (1997), as good estimators of both helical and sheet content.     

Applicability of microwave acid digestion to sample preparation of biological materials for analysis by particle-induced X-ray emission (PIXE)

A microwave acid digestion method for the preparation of biological samples for PIXE analysis is presented. The precision and accuracy of the entire PIXE analytical procedure, including the micro-wave digestion step, were evaluated by analyzing eight certified reference materials. For elements heavier than K, and for concentration levels from 2 μg/g upward, the total random error of a single analysis is in the range of 2–5%. The accuracy is better than 5%. The detection limits are down to 0.3 μg/g.

     

Ricerche Sulla Istologia del Legno Secondario Delle Gymnospermae

Summary

The anatomy and histology of the secondary wood of Pinus halepensis Mill. has been studied.

The wood of Aleppo Pine does not differ from that of the other Conifers already investigated.

The tracheids shaw a strong dimorphism, with the presence of prevalently conducting elements and strongly mecanic ones.

In both spring and autumn woods the two tipes of elements are to be found, although in different proportions.

The best character to espress this dimorphism seems to be »trachcids length «.

The conducting elements are shorter, while the mecanic ones are longer.     

Exposure assessment of potentially toxic trace elements via consumption of fruits and vegetables grown under the impact of Alaverdi's mining complex

This study is aimed to investigate the transfer of potentially toxic trace elements from soils to plants grown under the impact of Alaverdi's mining complex and assess the related dietary exposure to local residents. Contamination levels of potentially toxic trace elements (Cu, Ni, Pb, Zn, Hg, As, Cd) in soils and plants were determined and afterwards, transfer factors, estimated daily intakes, target hazard quotients, and hazard indexes were calculated.

Some trace elements (Pb, Zn, Cd) exceeded the maximum allowable levels. EDIs of Cu, Ni, Hg for the majority of studied fruits and vegetables exceeded the health-based guideline values. Meanwhile, in case of combined consumption of the studied food items, the estimated cumulative daily intakes exceeded health-based guideline values not only for the aforementioned trace elements but also for Zn in the following sequence: Zn > Hg > Ni > Cu. HI > 1 values highlighted the potential adverse health effects for local population through more than one trace element.

Detailed investigations need to be done for the overall assessment of health risks, taking into consideration not only adverse health effects posed by more than one toxic trace element but also through other exposure pathways.     

Speciation of copper in relation to its bioavailability

Abstract

Copper speciation and bioavailability for Scenedesmus quadricauda has been studied in natural waters and in synthetic culture media. Other elements were studied simultaneously. When phosphorus and nitrogen limitation were excluded by adding these elements, copper was limiting algal growth in some natural waters. In the toxic range, growth inhibition by copper was highly correlated with copper detected by electrochemical methods and with calculated free copper.

Copper was toxic to S. quadricauda when free copper concentrations roughly exceeded 10^?10.5 M, and was limiting for values somewhere lower than 10^?12.5 M. Because we found copper limitation in some natural water samples, free copper concentration in those water samples therefore must have been lower than 10^?12.5 M.

The hypothesis that the free metal concentration rather than the total concentration determines bioavailability was confirmed for copper, cobalt and zinc.     

Simultaneous analysis for multiple heavy metals in contaminated biological samples

In the present study, the conditions of analysis by inductively coupled plasma-atomic emission spectrometry (ICP-AES) were investigated. Twenty-six elements (Mg: 25 ppm; Sc: 10 ppm; Ti: 50 ppm; others: 100 ppm) were used as the elements interfering with selected 24 wavelengths. Consequently, the background values in 19 elements were subjected to some influences. However, all of these effects disappeared at low concentrations—less than 1 ppm of interfering elements. Next, the values from the ordinary calibration method were compared with those from the standard addition method using several biological samples. There was a discrepancy in the results obtained from both methods because of the sample, and three patterns were observed. However, no discrepancy was observed in the values for the standard reference materials using both methods. There was no significant difference between the certified values of the standard reference materials and the obtained ones by ICP. Therefore, the analytical wavelengths and the methods in the present study were suggested to be useful for ICP-AES analysis for environmental and/or biological samples.     

Computation of the bond dissociation enthalpies and free energies of hydroxylic antioxidants using the ab initio Hartree–Fock method

Abstract

Introduction

A new method for calculating theoretical bond dissociation enthalpy (BDE) and bond dissociation free energy (BDFE) of hydroxylic antioxidants is forwarded. BDE and BDFE may be understood as activation energies accompanying the formation of transition states, which may undergo downhill homolytic dissociation. The new method does not involve the complete fission of O–H bonds.

Method

Theoretical gas phase BDE values were calculated with the ab initio unrestricted Hartree–Fock (UHF) method, as changes in enthalpy between ground singlet states (GS) and triplet dissociative states (DS). Similarly, gas phase BDFEs were estimated from the corresponding changes in Gibbs free energy. The results were then compared with reliable experimental reports.

Results

The proposed theoretical approach of BDE and BDFE determination was tested using 10 simple phenols, 5 flavonoids, and l-ascorbic acid derivatives. The agreement between our calculated gas phase results and the adopted experimental values were generally within 0.5 kcal mol^?1, with a very few exceptions.

Discussion

Generally, steric interactions as well as intramolecular hydrogen bonding involving the dissociating OH group should be minimized in the GS. The DS are both electronically and vibrationally exited transition states. They have one unpaired electron on the carbon atom, which bears the homolytically dissociating OH group and are second order saddle points with a fixed <C–O–H bond angel of 180°.

Conclusion

It was concluded that ab initio UHF was well suited for the estimation of gas phase BDE and BDFE. The method presented has a good potential for application across a range of hydroxylic antioxidants. Currently, work is underway to extend its application in other class of antioxidants.