Bureau Communautaire De Reference Research Articles

Exchangeable versus residual metals in naturally aged plastic litter.

Metals may be associated with plastics as additives arising from manufacture or through acquisition from the environment, but these associations are often poorly defined or referred to synonymously when considering metal availability. In this study, samples of plastic litter (n = 22) have been collected from various environmental and industrial compartments of Lublin Province, Poland, and fractionated according to polymer type (polyethylene, polyethylene terephthalate, nylon, expanded polystyrene, polypropylene, and "mixed") before being micronised to < 2mm. Composites (n = 89) were subjected to two phases of a standardised and widely employed sequential extraction protocol (Bureau Communautaire de Reference; BCR) in order to define available (acid-soluble and exchangeable) and residual (soluble in boiling aqua regia) concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn. For a given metal, total content, calculated by summing available and residual components, was highly variable, both between locations and amongst polymer categories, reflecting the heterogeneous distribution of a multitude of different additives. Overall, however, concentrations were greatest for Fe, with medians of several hundred to several thousand mg kg-1 amongst the different polymers, and lowest for Cd, Co, and Ni, where nearly all concentrations were below 10mgkg-1. Median percentage metal availabilities were greatest for expanded polystyrene and were above 25% for Mn and Zn and below 10% for Cr and Fe in all polymer types. These observations are largely, but not entirely, attributed to the relative contributions of metals acquired from the environment and metals present as additives and residues. Significantly, the approach employed allows direct comparisons of metal availability in plastics with metal availability in environmental solids in order to evaluate the overall impacts of plastics in metal risk assessments.

Study of the heavy metal content of floodplain soils along the upper Tisza River by sequential BCR extraction in Hungary

In this study PTEs, [potentially toxic elements (Cr, Cu, Mn, Ni, Pb, and Zn)] were investigated in the upper layer of floodplain soils that occurred as a result of accident in the area of two mine tailings in Northwestern Romania. A large amount of sediment was deposited on the soil of floodplains along the Hungarian section of River Tisza, which could represent a threat to the environment. Floodplain soil samples were collected from four locations in Hungary from an area of the river stretching to about 250 km. BCR (Bureau Communautaire de Référence) sequential extraction method was used to analyze both post-flood and present samples. Most of the analyzed elements (Cd, Cr, Cu, Ni, Pb, Zn) were found in the residual fraction, but there is a notable soluble amount in hydroxylammonium chloride extractable fraction. The results allow a comparison of the changes that have taken place over time, in addition to serving as a basis for further studies.

Dissolved oxygen drives the environmental behavior of heavy metals in coastal sediments.

In this study, the impacts of dissolved oxygen (DO) on dynamics concentrations of heavy metals (Cu, Cd, Cr, and Pb) from estuary sediments were investigated in a 49-day laboratory simulation. The exchange flux method, Bureau Communautaire de Référence (BCR) sequential extraction procedure, and risk assessment code (RAC) were used to analyze the behavior of heavy metals. The results indicated that oxic environments promoted the concentrations of Cu and Cd in overlying water compared to the anoxic environments. The exchange fluxes showed that the diffusion of Cu, Cd, Cr, and Pb from sediments was the predominant process in the first 9days, and a metastable equilibrium state was gradually reached in the later period under anoxic conditions. However, oxic conditions extended the time required to reach metastable equilibrium for Cu over the sediment-water (overlying water) interface (SWI). Although the reducible fractions of Cu, Cd, and Pb accounted for a large proportion of their total levels, the release ability of Cu, Cd, and Pb was limited by the high content of sulfide under anoxic conditions. The RAC values indicated that anoxic environments increased the proportion of acid-soluble fraction. The information obtained from this study highlights the potential risk for re-release of heavy metal from sediments under different redox conditions.

Evolution of reference materials for the determination of organic nutrients in food and dietary supplements-a critical review.

For over 40years, food-matrix certified reference materials (CRMs) have been available for determination of trace element content, and a wide variety of materials are available from most producers of CRMs. However, the availability of food-matrix CRMs for organic nutrients has been more limited. The European Commission (EC) Bureau Communautaire de Référence (BCR) and the National Institute of Standards and Technology (NIST) introduced food-matrix CRMs with values assigned for vitamins and other organic nutrients such as fatty acids and carotenoids in the 1990s. The number of organic nutrients for which values were assigned has increased significantly in the past decade, and the approach and analytical methods used for assignment of the certified values have also evolved. Recently, dietary supplement-matrix CRMs such as multivitamin tablets with values assigned for vitamins and carotenoids, and fish and plant oils with values assigned for fatty acids have appeared. The development, evolution, and improvement of food- and dietary supplement-matrix CRMs for determination of vitamins, carotenoids, and fatty acids are described, with emphasis on CRMs made available in the past 10years. Recent food and dietary supplement CRMs for the determination of organic nutrients include infant formula, multivitamin tablets, milk and egg powders, breakfast cereal, meat homogenate, blueberries, soy flour, fish and plant oils, dry cat food, and protein drink powder. Many of these food- and supplement-matrix CRMs have values assigned for over 80 organic and inorganic nutrients, toxic elements, proximates, and contaminants. The review provides a critical assessment of the challenges and evolving improvements in the production and the analytical methods used for value assignment of these CRMs. The current status and future needs for additional food- and dietary supplement-matrix CRMs for organic nutrients are also discussed. Graphical abstract Food Composition Triangle with currently-available food-matrix certified reference materials (CRMs) for the determination of organic nutrients positioned according to fat, protein, and carbohydrate composition.

Immobilization of Eu and Ho from synthetic acid mine drainage by precipitation with Fe and Al (hydr)oxides.

Use of lime to mitigate acid mine drainage is, in general, accompanied by precipitation of iron (Fe) and aluminium (Al) (hydr)oxides which may increase the removal of trace elements from water. This work aimed to evaluate the precipitation of Fe/Al (hydr)oxides to remove rare earth elements (REE) from contaminated water and the stability of precipitates. Two sets of 60-day syntheses were carried out using different Fe/Al/REE molar ratios, for europium (Eu) and holmium (Ho). The pH was periodically adjusted to 9.0, and the stability of the resulting precipitates was evaluated by water-soluble and BCR extractable phases, namely (1) acid soluble, extracted by 0.11molL-1 acetic acid; (2) reducible, extracted with 0.5molL-1 hydroxylamine hydrochloride; and (3) oxidisable, extracted with 8.8molL-1 hydrogen peroxide efficiencies of the water treatments for both Eu and Ho that were higher than 99.9% irrespective to the Fe/Al/REE molar ratios. Water-soluble phases of Eu and Ho were lower than 0.01% of the total contents in the precipitates. Recoveries from precipitates by Bureau Communautaire de Référence (BCR) sequential extractions increased with increasing concentrations of Eu and Ho. Acetic acid extracted higher amounts of REE, but Eu recovery was superior to Ho. Lepidocrocite was formed as Eu concentration increased which decreased its stability in the precipitates.

Assessment of metal contamination in estuarine surface sediments from Dongying City, China: Use of a modified ecological risk index

Surface sediments and clam Meretrix meretrix were collected from a northern estuarine region in Dongying City, China. Sediments were analysed for heavy metals (Hg, As, Cd, Cr, Cu, Pb, and Zn) and the clams were tested for metallothioneins (MTs) and lysosomal membrane stability (LMS). The heavy metal total concentrations decreased in the order of Cr>Zn>Cu>Pb>As>Cd>Hg. The results of Bureau Communautaire de Référence (BCR) sequential extraction of heavy metals showed that the geochemical speciation of all heavy metals was dominated by residual fraction. According to the responses of biomarkers in M. meretrix, the modified potential ecological risk index (PERI-B) can more accurately reflect heavy metals pollution. PERI-B showed all sediment samples have low or moderate risk, except at site S10 (considerable risk), and the main contribution of ecological risk heavy metals were Cd and Hg.

Dosing of Ethylenediamine-N,N′-disuccinic acid (EDDS) to improve the bioavailability of Fe2+ in the presence of sulfide in a submerged anaerobic membrane bioreactor

This study evaluated the effect of 8mg/L sulfide on the speciation and bioavailability of 10mg/L iron (Fe2+), with and without a biodegradable chelating agent, Ethylenediamine-N,N′-disuccinic acid (EDDS). These tests were carried out in the presence of sulfide, in both batch assays, and in a continuous submerged anaerobic membrane bioreactor (SAMBR). The EDDS was added at 1:1M ratio to the Fe2+ (10mg/L), either simultaneously, or as Fe-EDDS complex. Results showed that adding 8mg/L of sulfide limited the bioavailability of Fe2+ by shifting its speciation toward less bioavailable fractions based on the Bureau Communautaire de Reference (BCR) extraction analysis, i.e. organic matter/sulfide and residual, resulting in a decrease in methane yields and an increase in VFA levels. An Fe-EDDS complex was found to be more effective controlling the change in sulfide levels in the SAMBR as it helped to reverse the shift in Fe2+ speciation, and increased methane yields by 9.46%.

Availability and fractionation of Cu, Pb and Zn in an acid soil from Galicia (NW Spain) amended with municipal solid waste compost

The potential availability and chemical fractionation of trace elements in soil after compost addition was studied in a laboratory incubation. An acid agricultural soil, developed on biotitic schists, was amended with two rates of a municipal solid waste compost (3% and 6% weight) or lime (2.5 g CaCO&lt;sub&gt;3&lt;/sub&gt; kg&lt;sup&gt;-1&lt;/sup&gt;, calculated to raise soil pH to values close to those of the compost-amended soil), and incubated in the laboratory for five months. Compost addition increased the availability of Cu, Pb and Zn (measured in DTPA extract) with respect to the control, whereas lime reduced it. Compost amendment increased soil total Cu, Pb and Zn concentrations, and their chemical distribution, assessed by means of the BCR (Bureau Communautaire de Reference) fractionation scheme, was different for each element. Compost addition increased Pb in the reducible (iron oxide-bound) fraction, Cu in the organic and iron oxide fractions, and Zn in the soluble and reducible fractions. Lime did not change the fractionation or total concentrations of the metals analysed. The most problematic element in the compost-amended soil from an environmental point of view is Zn, because it was found in highly mobile forms, while for Cu and Pb this risk is low.

Chemical speciation of heavy metals in excess sludge treatment by thermal hydrolysis and anaerobic digestion process

Adequate treatment of excess sludge from municipal wastewater treatment plants (WWTP) is a critical issue nowadays in WWTP management. Thermal hydrolysis and anaerobic digestion are the methods often used to reduce the organic content of the excess sludge. However, these two methods have very limited effects on heavy metals’ removal. As the toxicity of heavy metals is closely related to not only their quantity but also in their chemical speciations, more in-depth studies on heavy metals speciation distribution are needed. In this paper, the speciation of eight kinds of heavy metals before and after thermal hydrolysis and anaerobic digestion were investigated using a modified BCR (Bureau Communautaire de Référence: a four-step sequential extraction process proposed by the European Community Bureau of Reference in 1992) sequential extraction process. The results showed that the stable content of eight kinds of heavy metals increased by various extents after thermal hydrolysis. The chemical speciation of heavy metals during thermal hydrolysis and anaerobic digestion exhibited significant changes from non-stable to relatively stable state. The existence of H2S can reduce the activity of anammox bacteria, and thus can lead to the deterioration of anaerobic biological treatment system. However, the toxicity of H2S and heavy metal ions can be significantly inhibited simultaneously by the interaction between heavy metals and H2S without secondary pollution, which is beneficial for excess sludge disposal.

Copper and Zinc Fractionation in Apple Orchard Soil in the Village of Bukevje (Croatia) Using the Revised Four-Step BCR Extraction Procedure

The aim of this study was to establish the fractionation of copper and zinc in a small apple orchard using the revised (four-step) Bureau Communautaire de Référence (BCR) sequential extraction procedure and assess their potential mobility in soil. Soil samples were collected at the depth of 10 cm to 25 cm, sixteen from the orchard and five control samples from a meadow located some 200 m away from the orchard. As the distribution of trace-element concentrations in the control samples was normal, they were used for comparison as background levels. We also determined soil mineralogical composition, carbonate content, soil pH, cation exchange capacity, and soil organic matter. The extraction yields of Cu and Zn from the control soil were lower than from the orchard soil (25% vs. 34% and 47% vs. 52%, respectively), which pointed to natural processes behind metal bonding in the control soil and greater influence of man-made activities in the orchard soil. Compared to control, the orchard soil had significantly higher concentrations of total Cu (P=0.0009), possibly due to the application of Cu-based fungicides. This assumption was further supported by greater speciation variability of Cu than of zinc, which points to different origins of the two, Cu from pesticides and Zn from the parent bedrock. Copper levels significantly better (P=0.01) correlated with the oxidisable fraction of the orchard soil than of control soil. Residual and organically bound copper and zinc constituted the most important fractions in the studied soils. However, the use of Cu-based fungicides in the apple orchard did not impose environmental and health risk from Cu exposure.

Response to Letter to the Editor regarding the “European Analytical Column No. 41”

Dear Sir, It is possible that the philosophy of consensus science may question, to some extent, the basis for both analytical chemistry and metrology [1]. Change of practices and procedures may be needed; genuine scientific results may be lost and theories that rely on data out of statistical control may incorrectly be proven true. There is an obligation of science to make fundamental changes, and consensus science may be a useful example of scientific methodology. There is no evidence in modern analytical chemistry for the idea that experts are able to distinguish between reliable and unreliable analytical results. The experts have no access to raw data of inter-laboratory comparisons (ILCs) and they have no access to raw data of scientific publications. Therefore, they are left with comparing highly processed data, which is unfortunate for comparisons in analytical sciences. Scientists are subjective when they propose a model and should remain objective when they compare theory to experiments. To the best of my knowledge, the staff never imposes contributions to the uncertainty. Laboratory staff prepare everything carefully and correctly in the laboratory, and even in cases where errors are committed, these errors are small and insignificant in the general picture of uncertainty. The main contribution to uncertainty is the apparatus long-time precision, which has been overlooked in uncertainty budgets [2]. If this contribution were included, would it increase the likelihood of correspondence between results in ILCs? Presumably, a university or a company would never employ incompetent staff to operate advanced apparatus. Accordingly, it is reasonable to assume that all results of ILCs belong to the same distribution. The analytical capability of laboratories cannot be checked unless the universal level of uncertainty of the involved method is known. It may safely be assumed that everyone who has invested in advanced scientific apparatus also has the competence to perform measurements. I agree that a two-step procedure for selection of qualified laboratories in advance of an ILC is not an option because that would be in conflict with consensus science. The idea of all laboratories showing equal degrees of competence is unattainable. Staff need acceptable working conditions and the results should be provided with a reasonable consumption of resources, labor, time etc. Nature does not care about ILCs and legislation. It cannot be decided by politics or debate whose fundamental constants in metrology or whose analytical results are right or wrong. We can only approach the true mechanisms of nature by performing measurements that possess a certain level of uncertainty. Hence, the method of consensus should be prevalent in science. Nothing can be decided by a single expert; results of many independent experts are required in order to maintain independence and credibility. It was interesting to me that the author of the ‘Letter to the Editor’ stated that outliers had been removed from the data set that constitutes the basis for certified reference materials (CRMs). Novel types of outliers, identified as ‘analytical outliers’, were invented for the occasion that supposedly should be distinguished from ‘statistical outliers’. It was not possible to find the technical reasons, as otherwise claimed possible. Hendrik Emons militates against better judgment: outliers were, in fact, rejected in BCR CRMs on the basis of statistical reasons and not due to technical reasons. Just a few examples: “The set of Lab 14 was rejected because its standard error exceeded s” [Bureau communautaire de reference, BCR Wholemeal flour CRM no. 189/Brown bread CRM no. 191] or “Laboratory 5 (TXRF) had an outlying variance for total Cr (Annex 1, Table 3a) and did not satisfy the criterion for This article is a response to the ‘Letter to the Editor’ to be found at DOI 10.1007/s00216‐013‐7141-5.

Assessment of trace and heavy metal distribution by four sequential extraction procedures in a contaminated soil

Four sequential extraction procedures (Sposito, Tessier, Silveira and Bureau Communautaire de Reference (BCR)) were used to evaluate the distribution of some metals (Fe, Cu, Cd and Zn) in a contaminated soil around a mining area. The results showed that Fe and Zn were mainly recovered in the recalcitrant soil fractions, while Cd was primarily localized in the exchangeable fraction. Soil Cu was highly associated with organic matter fraction. The amorphous Fe fraction in Silveira could be recognized as part of the Fe-Mn oxide fraction in Tessier and BCR procedures, while the crystalline Fe oxide fraction was classified into the residual fraction in Sposito, BCR and Tessier schemes. Although the same reagent was used to extract target fraction, less carbonate-bound Cu, Cu and Zn were extracted in Tessier procedure as compared to Silveira method, while Tessier scheme yielded a higher proportion of Fe, Cu and Zn in the Fe-Mn oxide fraction than BCR method. Due to the lack of uniformity of experimental conditions and the differences in extraction reagents, the extraction efficiency of metal species varied with the sequential extraction schemes. Therefore, care should be taken when comparing the results obtained by different sequential extraction procedures.

Evaluation of a Collision-Reaction Interface (CRI) for Carbon Effect Correction on Chromium Determination in Environmental Samples by ICP-MS

Spectral interferences in inductively coupled plasma quadrupole mass spectrometry (ICP-MS) may affect several trace element analyses. In this work, the performance of a collision-reaction interface (CRI) for correction of spectral interferences on chromium determination at m/z 52 affected by 40Ar12C+ in a rich-carbon medium was evaluated. Hydrogen or He gases were introduced through sampler or skimmer cones of the CRI for promoting collisions and reactions. Background equivalent concentrations (BEC) and signal-background ratios (SBR) were the chosen parameters for evaluating CRI performance. It was observed that the introduction of both gases through the sampler cone was not effective considering the maximum gas flow rate evaluated at 140 mL min−1. The best condition to reduce polyatomic interferences caused by carbon containing species was obtained while introducing 60 mL min−1 of H2 through the skimmer cone. The trueness of the developed procedure was checked by 52Cr+ determination in certified reference materials. Sequential extractions in acetic acid and ammonium acetate (carbon sources) media, according to the Bureau Communautaire de Référence (BCR) of the Commission of the European Communities, was employed for BCR 701 (Lake Sediment) and microwave-assisted digestion was applied for Sewage Sludge from Industrial Origin (BCR 146 R). The feasibility of the CRI to overcome spectral interferences caused by molecular ions containing carbon on 52Cr+ determined by ICP-MS was demonstrated.

Speciation of Heavy Metals in the Surface Sediments from Northern Beibu Gulf

The four species of heavy metals (Cu, Zn, Pb, Cr, Cd) were analyzed using BCR (the Bureau Communautaire de Reference) sequential extraction method. Results showed that, about the contents the four species (exchangeable and carbonate state, Fe-Mn oxides state, organic and sulfide state and residual state) in surface sediment, the average contents of Cu were 0.94 μg/g, 2.17 μg/g, 1.18 μg/g and 13.19 μg/g, respectively. the average contents of Pb were1.51 μg/g, 12.90 μg/g, 4.51 μg/g and 16.42 μg/g, respectively; the average contents of Zn were 1.82 μg/g, 13.00 μg/g, 4.20 μg/g and 48.97 μg/g, respectively; the average contents of Cd were 0.010 μg/g, 0.012 μg/g, 0.005 μg/g and 0.063 μg/g, respectively; the average contents of Cr were 0.32 μg/g, 2.98 μg/g, 4.22 μg/g and 13.19 μg/g, respectively. The predominant species of Cu, Zn, Pb, Cr, Cd is residual state. The relative abundance in residual state for these elements followed the order: Cr＞Cu＞Zn＞Cd＞Pb. The pollution degree was assessed with ratio of secondary phase to primary phase. Results showed that the sediments in the northern Beibu Gulf were uncontaminated with Cu, Zn and Cr. 12 % of the sites was slightly polluted with Cd. 47 % of the sites were polluted with Pb.

Electrokinetic remediation: The use of mercury speciation for feasibility studies applied to a contaminated soil from Almadén

We have chosen the BCR (Bureau Communautaire de Référence) sequential extraction procedure as a speciation analysis to determine the mobility of mercury in the contaminated soil of the Almadén (Spain) mining district. This soil has a high mercury concentration (1000 mg kg −1) in some areas. In previous works, the relationship between the weak-acid soluble fraction and the amount of contaminant recoverable by acid-enhanced electrokinetic remediation (EKR) was shown. In this study, after testing that this relationship is maintained, we test if similar relationships with chelating agents could be established. Recently, several chelating agents were tried and iodide was shown to be quite efficient for the removal of mercury. Thus we have carried out iodide-enhanced EKR experiments at the lab (16 g of soil) and semi-pilot (2 kg) scales. From these experiments it can be concluded that the amount of mercury recoverable by this technique is similar to the one recovered in the batch extraction experiments. Thus, this is another evidence that this kind of experiments can be used for the feasibility studies of the remediation technique. It is also shown that, although the removal efficiency is similar to the one obtained previously for in situ flushing, the time required to achieve this efficiency would be several orders of magnitude shorter for this soil. Nevertheless, the residual Hg present in the weak-acid soluble fraction of the speciation analysis of the soil after the EKR treatment increases with respect to the original contaminated soil, indicating a possible increase of the risks associated to the contaminated site. Therefore, a second EKR treatment is applied to the same soil, this time using acid-enhanced EKR. It is shown that, although almost no Hg was recovered with this technique for the original soil, an important amount can be recovered after the first treatment (iodide-enhanced EKR). Also it is shown that the design and operation of this second technique should be studied carefully due to the rather complex chemistry of the species involved.

The Desorption of Antimony(V) from Sediments, Hydrous Oxides, and Clay Minerals by Carbonate, Phosphate, Sulfate, Nitrate, and Chloride

The desorption of antimony, Sb(V), from two sediment samples by phosphate, carbonate, sulfate, chloride, and nitrate at pH 8 was examined. One highly contaminated sediment sample was taken from an Sb mine (Goesdorf, Luxembourg); the other sample was the certified reference material PACS-2 (marine sediment). Phosphate was found to have a strong mobilizing ability, whereas that of carbonate was in general weaker. For comparison, and to understand better the possible importance of individual components of the sediments, desorption experiments were performed on pure phases (i.e., hydrous oxides of Fe, Mn, and Al) and the clay minerals kaolinite and montmorillonite. In the cases of hydrous metal oxides, Sb(V) was most effectively desorbed by phosphate, followed by carbonate. Phosphate also desorbed Sb(V) from the clay minerals, whereas carbonate had no effect. The pH dependence of adsorption of Sb(V) in the absence and presence of carbonate revealed that adsorption densities were higher (except in the case of montmorillonite) in the absence of carbonate, suggesting a competition between carbonate and [Sb(OH)] for surface sites generally and a lowering of surface charge in the case of hydrous aluminum oxide. The observations are unlikely to be due to ionic strength effects because activity coefficients in the blank and spiked solutions differ by <4%. Desorption experiments on sediments with varying concentrations of phosphate and carbonate demonstrated that at environmentally relevant concentrations, desorption by phosphate is negligible, whereas the effect of carbonate is not. Sulfate, chloride, and nitrate generally had little effect. The proportion of Sb desorbed in blank experiments coincides with that mobilized in the first fraction of the Bureau Communautaire de Référence (BCR) sequential extraction (easily exchangeable and carbonate-bound fraction).

Urbanization impact on metals mobility in riverine suspended sediment: Role of metal oxides

Spatial and temporal fractionation of trace metals and major elements in suspended particulate matter in the Seine River was investigated to study the impact of the increasing urbanization in the Greater Paris Region. Suspended sediments in the Seine River were collected between December 2008 to August 2009 upstream and downstream of Paris. They were subjected to total digestion and sequential extraction procedure certified by the Bureau Communautaire de Reference and trace metals along with major elements were analyzed with inductively coupled plasma mass spectroscopy. Metal enrichment factors increased up to eight folds after the Seine River downstream of the Greater Paris Region showing a significant contribution of urbanization. Enrichment of copper, lead and zinc downstream of Paris are followed by the increase of their reducible fraction of at least 10% implicating an increase in metals associated with iron oxides. The exchangeable fraction, which includes the carbonate-associated metals, is only significant for cadmium, nickel and zinc (more than 2 %) while the oxidisable fraction accounts for less than 20 % for the anthropogenic metals downstream except for copper. The metals can be divided to (a) “reducible” group including cadmium, lead, and zinc, associated with more than 60 % of the total Bureau Communautaire de Reference extractable metals to the reducible fraction containing mostly iron oxide phases for the downstream sites. (b) A “distributed” group including chromium, copper, and nickel that are associated to at least 3 different phase-groups: (1) oxides, (2) organic matter and sulphides and (3) mineral phases.

Comparison of two sequential extraction protocols for fractionation of natural radionuclides in soil samples

Revised BCR (Bureau Communautaire de Référence) and the Schultz modification of Tessier´s sequential extraction protocols are compared for fractionation of uranium, thorium and radium in soil samples. Six soil samples were collected near to the uranium mill tailings waste pile and some of them had enhanced levels of natural radionuclides. The samples were processed by both protocols and the radionuclide content assayed by alpha spectrometric determination. The analysis revealed that results obtained by the two protocols are not fully comparable as data are mostly protocol- and element-dependent. Nevertheless, general conclusions about potential source of the particular radionuclide, which could be drawn from the specific study carried out, are mostly similar for both protocols.

Instrumental neutron activation analysis of mass fractions of toxic metals in plastic

It is very challenging to decompose a plastic product for the purpose of analysis of hazardous elements contained. To circumvent such technical problem, it is imperative that an analyst employ a nondestructive analytical method free of any pretreatments. The analytical results of the concentrations of toxic metals such as Cd and Cr in polypropylene for seven samples at two different levels were obtained using the instrumental neutron activation analysis. This work was intended ultimately to establish certified reference materials (CRMs) of these metals in the polypropylene, traceable to the SI. The uncertainties associated with the analytical procedures were estimated in accordance with the ISO guideline. The results were subsequently validated by a comparison with those for CRM-680 and −681 of the Bureau Communautaire de Reference (BCR), which demonstrated acceptable agreement within their uncertainty ranges.

Chemical Fractionation of Trace Elements in Biosolid‐Amended Soils and Correlation with Trace Elements in Crop Tissue

A previous study indicated that agricultural biosolid applications increased the concentration of EPA3050‐digestible trace elements in soils on Pennsylvania production farms but could not indicate potential trace‐element environmental availability. This study was conducted to determine if biosolid application had altered the distribution of trace‐elements among operationally defined soil fractions and the relationship of trace element concentrations in soil and crop tissues. Biosolid‐amended and unamended soils from production farms in Pennsylvania were extracted using a modified Bureau Communautaire de Référence (BCR) sequential fractionation technique and analyzed for chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn). Trace‐element concentrations in crop tissues (soybean silage, sudangrass, corn grain, alfalfa hay, and orchardgrass hay) from the same farms were also determined. Fractionation results indicated that the proportion of Cr, Cu, Ni, Pb, and Zn that is potentially bioavailable is quite small in unamended soils. Biosolid applications significantly (P≤0.1) increased concentrations of Cu in all soil fractions (average increase over unamended soil=1.14, 8.27, 6.04, and 5.84 mg kg−1 for the exchangeable, reducible, oxidizable, and residual fractions, respectively), Ni (0.41, 1.65 mg kg−1 for the reducible and residual fractions, respectively), Pb (5.12 and 1.49 mg kg−1 for the reducible and residual fractions, respectively), and Zn (8.28, 7.12, 4.44, and 8.98 mg kg−1 for the exchangeable, reducible, oxidizable, and residual fractions, respectively) but did not significantly increase Cr in any soil fraction. Concentrations of Cu in all soil fractions were significantly (P≤0.01) correlated with concentrations of Cu in orchardgrass tissue (r=0.70, 0.66, 0.76, and 0.69 for the exchangeable, reducible, oxidizable, and residual soil fractions, respectively). Concentrations of exchangeable and reducible Zn were significantly correlated with Zn in sudangrass tissue (r=0.81 and 0.67), and reducible Zn was significantly correlated with Zn concentrations in orchardgrass tissue (r=0.65). Application of biosolids had little effect on bioavailability of Cr, Ni, or Pb, whereas higher loadings of Cu and Zn led to a shift toward the more labile soil fractions. Loadings of Cu and Zn were much smaller than cumulative loadings permitted under U.S. Environmental Protection Agency (USEPA) Part 503 regulations. Chemical soil fractionation was able to detect increases in labile soil Cu and Zn that relate to increased phytoavailability.