Environmental distribution of uranium and other trace elements at selected Kosovo sites

This paper reports the results of a study using lichens as biomonitors to investigate the environmental distribution of uranium and other trace elements at selected Kosovo sites. The results suggested that the use of depleted uranium (DU) ammunitions in Kosovo did not cause a diffuse environmental contamination in such a way to have caused a detectable U enrichment in lichens. Also isotopic (235)U/(238)U measurements did not indicate the presence of DU particles in lichens. The present results also provided no indication of intense environmental contamination by the other trace elements analyzed, with the exception of Kosovska Mitrovica, where a diffuse environmental contamination by several heavy elements such as Pb, Zn, As and Cd was found.     

Depleted uranium mobility and fractionation in contaminated soil (Southern Serbia)

GOAL, SCOPE AND BACKGROUND: During the Balkan conflict in 1999, soil in contaminated areas was enriched in depleted uranium (DU) isotopic signature, relative to the in-situ natural uranium present. After the military activities, most of kinetic DU penetrators or their fragments remained buried in the ground in certain geomorphological and geochemical environments exposed to local weathering conditions. The contamination distribution, mobility and/or fixation of DU in the contaminated soil profile at one hot spot were the subject of our study. The results should disclose what happened with released DU corrosion products in three years elapsed, given the scope of their geochemical fractionation, and mark out the most probable host substrates in investigated soil type. METHODS: Gamma-spectrometric analysis of soil samples taken in the DU penetrator impact-zone was done to obtain present contamination levels. Set of samples is subjected to five-step and three-step sequential extraction procedures, specifically selective to different physical/chemical associations in soil. The stable elements are determined in extracts by the atomic absorption spectroscopy. After the ion-exchange based uranium separation procedure, alpha-spectrometric analysis of obtained fractions was done and DU distribution in five extraction phases found from 235U/238U and 234U/238U isotopic ratios. RESULTS: Depleted uranium concentration falls down to the 1% of the initial value, at approximately 150 mm distance to the source. Carbonates and iron/manganese hydrous oxides are indicated as the most probable substrates for depleted uranium in the characterized soil type. Therefore, in the highly contaminated soil samples, depleted uranium is still weakly bonded and easy exchangeable. The significant levels of organic-bonded depleted uranium are found in surface soil only. DISCUSSION: Dependence of the fractionation on the contamination levels is evident. Samples with higher DU contents have shown a longer maintenance in the exchangeable phases, probably because adsorption/desorption mass transfer through the medium was not very fast. Organic-bonded, depleted uranium is present in surface soil samples due to its higher humus content. Considering geochemical composition of investigated soil, the indicating chemical associations as substrates are in agreement with some considerations based on the results for low-level waste unsaturated zones. CONCLUSIONS: The soil contamination with depleted uranium in investigated area is still 'spot' type and not widespread. Dependence of the fractionation on the contamination levels and presence of weakly bonded, depleted uranium in the hot spots areas is evident. RECOMMENDATIONS AND PERSPECTIVES: A detailed study may be undertaken with suitable extractive reagents to define a bio-available fraction of depleted uranium in soil. The comparison of results for different soil types investigated by the same methodology may be useful. An applied combination of physical/chemical procedures and analysis may help in the decision making on the remediation strategy for sites contaminated with depleted uranium used in military operations.     

Sorption and bioreduction of hexavalent uranium at a military facility by the Chesapeake Bay

Directly adjacent to the Chesapeake Bay lies the Aberdeen Proving Ground, a U.S. Army facility where testing of armor-piercing ammunitions has resulted in the deposition of >70,000 kg of depleted uranium (DU) to local soils and sediments. Results of previous environmental monitoring suggested limited mobilization in the impact area and no transport of DU into the nation's largest estuary. To determine if physical and biological reactions constitute mechanisms involved in limiting contaminant transport, the sorption and biotransformation behavior of the radionuclide was studied using geochemical modeling and laboratory microcosms (500 ppb U(VI) initially). An immediate decline in dissolved U(VI) concentrations was observed under both sterile and non-sterile conditions due to rapid association of U(VI) with natural organic matter in the sediment. Reduction of U(VI) to U(IV) occurred only in non-sterile microcosms. In the non-sterile samples, intrinsic bioreduction of uranium involved bacteria of the order Clostridiales and was only moderately enhanced by the addition of acetate (41% vs. 56% in 121 days). Overall, this study demonstrates that the migration of depleted uranium from the APG site into the Chesapeake Bay may be limited by a combination of processes that include rapid sorption of U(VI) species to natural organic matter, followed by slow, intrinsic bioreduction to U(IV).     

Environmental distribution of mercury and other trace elements in the geothermal area of Bagnore (Mt. Amiata, Italy).

The environmental distribution of mercury and other trace elements in the geothermal area of Bagnore (Mt. Amiata, central Italy) and its surroundings was evaluated by means of lichens used as bioaccumulators. Adopting a 'before-after' strategy, the impact of a recently built power plant was also evaluated. Four sites were sampled: (1) S. Fiora, a town 2 km SE of Bagnore; (2) Bagnore, a village where geothermal power is generated; (3) Aiole, a locality 1.5 km NW of Bagnore with an abandoned Hg smelting plant and a waste pile of roasted cinnabar; (4) Arcidosso, a town 3.5 km NW of Bagnore. At S. Fiora and Arcidosso, where most of the population is concentrated, mercury levels in lichens were within the background range (0.1-0.2 microg/g dw). On the contrary, at Aiole, Hg concentrations (0.63-0.67 microg/g dw) were much higher than background. After the new geothermal power plant went into operation at Bagnore, lichen concentrations of Hg showed a 50% increase from 0.22 to 0.32 microg/g dw. This value, however, is in line with those found in lichens from natural areas with hot springs and fumaroles.     

The potential of lichens as long-term biomonitors of natural and artificial radionuclides

Lichens were used as biomonitors of Chernobyl fallout 137Cs, of cosmogenic 7Be and of radioactive members of the natural uranium and thorium decay chains. Samples were taken from two locations in France, including lichens sampled at different distances of a coal fired power plant and close to a uranium ore processing waste disposal site. All samples were analyzed gamma-spectrometrically after equilibrium concentrations of short-lived isotopes had been attained. Activity concentrations of the members of the uranium and thorium decay chains in Parmelia sulcata sampled 1994 decrease with distance from the plant, whereas in lichens taken at the waste disposal site a decrease with time was observed. Comparison of 7Be activity concentrations measured in lichens with atmospheric deposition rates confirms that P. sulcata can be used as a quantitative biomonitor of radioactive trace substances. Retention half-lives calculated with a simple one-compartment model are 2.6 +/- 1.2 years for cesium, which was detected in all samples even more than a decade after the Chernobyl accident, and of 0.7 (+/- 0.1) to 3.3 (+/- 0.7) years for lead. Consequences of our results for model identifiability and parameter estimation of a two-compartment model are discussed.     

Baseline concentrations of elements in the Antarctic macrolichen Umbilicaria decussata

Total concentrations of major and trace elements were determined in samples of the epilithic lichen Umbilicaria decussata from 24 ice-free areas in coastal Victoria Land (Antarctica). Overall average concentrations of trace elements except Cd were the lowest ever reported for lichens of the genus Umbilicaria. Specifically, the mean level of Pb in lichens from granitic rocks (0.46 +/- 0.18 microg g(-1) dry wt) was more than four times lower than the lowest record in Arctic lichens. No impact of local human activities was detected, but the elemental composition of U. decussata was affected by entrapment of soil or rock dust particles and probably by uptake of soluble elements from substrate. Relationships between elements and their distribution patterns in the study area indicated that the marine environment is the main source of major ions and perhaps of Cd in lichens. Accumulation of P was detected in samples from coastal sites frequented by seabirds. Although the present results can be taken as baseline levels of major and trace elements in Antarctic U. decussata from substrates with very different geochemical features, further research is necessary to evaluate the relative element contribution from each substrate with respect to those from snow, marine aerosol, salt encrustations and guano.     

Lichens as an integrating tool for monitoring PAH atmospheric deposition: A comparison with soil, air and pine needles

The aim of this study was to validate lichens as biomonitors of PAH atmospheric deposition; for that, an inter-comparison between the PAH profile and concentrations intercepted in lichens with those of air, soil and pine needles was performed. The study was conducted in a petro-industrial area and the results showed that PAH profiles in lichens were similar to those of the air and pine needles, but completely different from those of soils. Lichens accumulated higher PAH concentrations when compared to the other environmental compartments and its concentrations were significantly and linearly correlated with concentrations of PAHs in soil; we showed that a translation of the lichen PAHs concentrations into regulatory standards is possible, fulfilling one of the most important requirements of using lichens as biomonitors. With lichens we were then able to characterize the air PAHs profile of urban, petro-industrial and background areas.     

Radionuclides and heavy metals in Borovac,Southern Serbia

BACKGROUND, AIM, AND SCOPE: The paper presents the complex approach to the assessment of the state of the environment in Southern Serbia, surroundings of Bujanovac, the region which is of great concern as being exposed to contamination by depleted uranium (DU) ammunition during the North Atlantic Treaty Organization (NATO) attacks in 1999. It includes studies on concentrations of radionuclides and heavy metals in different environmental samples 5 years after the military actions. MATERIALS AND METHODS: In October 2004, samples of soil, grass, lichen, moss, honey, and water were collected at two sites, in the immediate vicinity of the targeted area and 5 km away from it. Radionuclide ((7)Be, (40)K, (137)Cs, (210)Pb, (226)Ra, (232)Th, (235)U, (238)U) activities in solid samples were determined by standard gamma spectrometry and total alpha and beta activity in water was determined by proportional alpha-beta counting. Concentrations of 35 elements were determined in the samples of soil, moss, grass, and lichen by instrumental neutron activation analysis (INAA). RESULTS: The results are discussed in the context of a possible contamination by DU that reached the environment during the attacks as well as in the context of an environmental pollution by radionuclides and heavy metals in Southern Serbia. The results are compared to the state of environment in the region and other parts of the country both prior to and following the attacks. DISCUSSION: This is the first comprehensive study of the contents of radionuclides and heavy metals in Southern Serbia and consequently highly important for the assessment of the state of environment in this part of the country concerning possible effects of DU ammunition on the environment, as well as anthropogenic source of pollution by radionuclides and heavy metals and other elements. Also, the highly sensitive method of INAA was used for the first time to analyze the environmental samples from this area. CONCLUSIONS: The results of the study of radionuclides in the samples of soils, leaves, grass, moss, lichen, honey, and water in Southern Serbia (Bujanovac) gave no evidence of the DU contamination of the environment 5 years after the military actions in 1999. Activities of radionuclides in soils were within the range of the values obtained in the other parts of the country and within the global average. The ratio of uranium isotopes confirmed the natural origin of uranium. In general, concentrations of heavy metals in the samples of soils, plant leaves, mosses, and lichen are found to be less or in the lower range of values found in other parts of the country, in spite of the differences in plant and moss species or soil characteristics. Possible sources of heavy metal contamination were identified as a power coal plant in the vicinity of the sampling sites and wood and waste burning processes. RECOMMENDATIONS AND PERSPECTIVES: The collected data should provide a base for the health risk assessments on animals and humans in the near future. It should be emphasized that the sampling was carried out 5 years after the military action and that the number of samples was limited; therefore, the conclusions should be accepted only as observed tendencies and a detailed study should be recommended in the future.     

Bioaccumulation behaviour of transplants of the lichen Flavoparmelia caperata in relation to total deposition at a polluted location in Portugal

This experiment compares the short and long time element accumulation behaviour of transplants of Flavoparmelia caperata lichen thalli and total deposition in an atmospheric polluted area. It was found that lichens exposed for a short time behaved differently from lichens in cumulative exposition suggesting the presence of acclimatization behaviour. The lichen transplant elemental content does not unequivocally represent the average or cumulative environmental availability of the exposure period. Reflection characteristics depend on the element and the lichen physiological conditions. Good correlations between lichen elemental contents and total deposition were obtained when a physiological lichen parameter was introduced in a mathematical model, suggesting that metabolically mediated accumulation is important.     

Biodiversity of epiphytic lichens and air pollution in the town of Siena (central Italy).

The results of a biomonitoring survey carried out in the town of Siena (central Italy) using the biodiversity of epiphytic lichens as indicator of air pollution are reported. The general picture was rather good, with more than 60% of the study area being in the categories "semi-natural" or "natural" according to a calibrated scale of environmental naturality/alteration. Compared with the situation of 1995, ameliorating conditions were found as a result of an improvement in air quality over time.     

Uranium bioaccumulation and biological disorders induced in zebrafish (Danio rerio) after a depleted uranium waterborne exposure

Because of its toxicity and its ubiquity within aquatic compartments, uranium (U) represents a significant hazard to aquatic species such as fish. In a previous study, we investigated some biological responses in zebrafish either exposed to depleted or to enriched U (i.e., to different radiological activities). However, results required further experiments to better understand biological responses. Moreover, we failed to clearly demonstrate a significant relationship between biological effects and U radiological activity. We therefore chose to herein examine U bioaccumulation and induced effects in zebrafish according to a chemical dose-response approach. Results showed that U is highly bioconcentrated in fish, according to a time- and concentration-dependent model. Additionally, hepatic antioxidant defenses, red blood cells DNA integrity and brain acetylcholinesterase activity were found to be significantly altered. Generally, the higher the U concentration, the sooner and/or the greater the effect, suggesting a close relationship between accumulation and effect.     

Can we predict uranium bioavailability based on soil parameters? Part 2: soil solution uranium concentration is not a good bioavailability index

The present study aimed to quantify the influence of soil parameters on uranium uptake by ryegrass. Ryegrass was established on eighteen distinct soils, spiked with (238)U. Uranium soil-to-plant transfer factors (TF) ranged from 0.0003 to 0.0340kgkg(-1). There was no significant relation between the U soil-to-plant transfer (or total U uptake or flux) and the uranium concentration in the soil solution or any other soil factor measured, nor with the U recovered following selective soil extractions. Multiple linear regression analysis resulted in a significant though complex model explaining up to 99% of variation in TF. The influence of uranium speciation on uranium uptake observed was featured: UO(2)(+2), uranyl carbonate complexes and UO(2)PO(4)(-) seem the U species being preferentially taken up by the roots and transferred to the shoots. Improved correlations were obtained when relating the uranium TF with the summed soil solution concentrations of mentioned uranium species.     

Lichens and mosses as biomonitors of trace elements in areas with thermal springs and fumarole activity (Mt. Amiata, central Italy)

The contribution of thermal springs and fumaroles to environmental levels of Al, As, B, Cd, Cu, Fe, Hg, Mo, Pb, S, Sb and Zn was evaluated by means of lichens (Parmelia sulcata) and mosses (Hypnum cupressiforme) used as bioaccumulators. Compared to the data reported for unpolluted areas, accumulation of Hg, S and Al was found, with values of Hg and S in the same range as in the vicinity of geothermal power plants. Furthermore, fumaroles turned out to be a significant source of atmospheric arsenic.     

Uranium contents in plants and mushrooms grown on a uranium-contaminated site near Ronneburg in Eastern Thuringia/Germany

Uranium concentrations in cultivated (sunflower, sunchoke, potato) and native plants, plant compartment specimens, and mushrooms, grown on a test site within a uranium-contaminated area in Eastern Thuringia, were analyzed and compared. This test site belongs to the Friedrich-Schiller University Jena and is situated on the ground of a former but now removed uranium mine waste leaching heap. For determination of the U concentrations in the biomaterials, the saps of the samples were squeezed out by using an ultracentrifuge, after that, the uranium concentrations in the saps and the remaining residue were measured, using ICP-MS. The study further showed that uranium concentrations observed in plant compartment and mushroom fruiting bodies sap samples were always higher than their associated solid residue sample. Also, it was found that the detected uranium concentration in the root samples were always higher than were observed in their associated above ground biomass, e.g., in shoots, leaves, blossoms etc. The highest uranium concentration was measured with almost 40 ppb U in a fruiting body of a mushroom and in roots of butterbur. However, the detected uranium concentrations in plants and mushrooms collected in this study were always lower than in the associated surface and soil water of the test site, indicating that under the encountered natural conditions, none of the studied plant and mushroom species turned out to be a hyperaccumulator for uranium, which could have extracted uranium in sufficient amounts out of the uranium-contaminated soil. In addition, it was found that the detected uranium concentrations in the sap samples, despite being above the sensitivity limit, proved to be too low—in combination with the presence of fluorescence quenching substances, e.g., iron and manganese ions, and/or organic quenchers—to extract a useful fluorescence signal, which could have helped to identify the uranium speciation in plants.     

Reduction of U(VI) by the deep subsurface bacterium, Thermus scotoductus SA-01, and the involvement of the ABC transporter protein

In this study we investigated the effect of uranium on the growth of the bacterium Thermus scotoductus strain SA-01 as well as the whole cell U(VI) reduction capabilities of the organism. Also, site-directed mutagenesis confirmed the identity of a protein capable of a possible alternative mechanism of U(VI) reduction. SA-01 can grow aerobically in up to 1.25 mM uranium and has the capability to reduce low levels of U(VI) in under 20 h. TEM analysis performed on cells exposed to uranium showed extracellular and membrane-bound accumulation of uranium. The reductase-like protein was surprisingly identified as a peptide ABC transporter, peptide-binding protein. This study showcases the concept of protein promiscuity, where this protein with a distinct function in situ can also have the unintended function of a reactant for the reduction of U(VI).     

Concentration of trace elements in blood and feed of homebred animals in Southern Serbia

Background, aim and scope  

The paper presents concentrations of trace elements in blood of homebred animals (cows and sheep) from Southern Serbia (Bujanovac) and the contents of natural and anthropogenic radionuclides and some heavy metals in feed. The region of Southern Serbia was exposed to contamination by depleted uranium ammunition during NATO attacks in 1999 and therefore, is of great concern to environmental pollution and human and animal health.     

Uptake and mobility of uranium in black oaks: implications for biomonitoring depleted uranium-contaminated groundwater

In a preliminary study, the uptake and the mobility of uranium (U) by black oak trees (Quercus velutina) were assessed by measuring the isotopic composition of tree rings in two mature oak trees in a heavy metal contaminated bog in Concord, MA. The bog is adjacent to a nuclear industrial facility that has been processing depleted uranium (DU) since 1959. Over the past 40 years, DU has been leaking from an onsite holding basin and cooling pond down gradient to the bog where the oaks are located. Because DU has no source outside the nuclear industry, contamination from the industrial facility is readily discernable from uptake of natural U by measuring isotopic compositions. Isotope ratio analysis confirms the occurrence of DU in bark, sapwood and heartwood tree rings dating back to 1937, pre-dating the introduction of DU at the site by at least 20 years. Isotope dilution analysis indicates high concentrations of U (>3 ppb) in sapwood that drop rapidly to relatively constant concentrations (0.3-0.4 ppb) in heartwood. These data indicate that once incorporated into tree cells, U is mobile, possibly by diffusion through the tree wood. Concentrations of U in sapwood are approximately equal to average U concentrations in groundwater onsite over the past 10 years, suggesting that oak trees can be used as present-day bioindicators of U-contaminated groundwater. We suggest that regional sampling of oak bark and sapwood is a reasonable, inexpensive alternative to drilling wells to monitor shallow groundwater U contamination.     

Lichens as integrating air pollution monitors

In this work an attempt to combine the results of lichen mapping with the quantitative levels of certain trace elements in Hypogymnia physodes (L.) Nyl. collected on a national scale is presented. An Index of Atmospheric Purity (IAP) was calculated using a simple method of mapping lichens based on the assessment of the cover and frequency of crustose, foliose and fruticose lichens on different tree species. For determination of trace elements in lichens k0-instrumental neutron activation analysis was used. From the IAP results it can be concluded that the epiphytic lichen flora look quite poor with more than 70% of the territory in the fourth and third classes, which represent highly polluted and moderately polluted air. By comparing IAP results with elemental levels in H. physodes using multivariate statistical methods it was found that the elemental levels do not have a direct negative effect on the diversity of lichens but can help in identification of the type of possible pollution sources and their origin.     

Exposure of Chironomus riparius larvae to uranium: effects on survival, development time, growth, and mouthpart deformities

Among non-biologically essential metals, data concerning uranium effects on freshwater benthic macroinvertebrates are scarce. The effects of uranium on survival, development time, growth and mouthpart deformities of midge Chironomus riparius were investigated. A 10-day static laboratory bioassay was performed exposing first instar larvae to artificial sediment spiked with four concentrations of uranium (2.97; 6.07; 11.44; 23.84 microg U g(-1) dry wt). As uranium was released from the sediment to the overlying water during this bioassay, both the sediment and the water column act as contamination pathways in giving rise to the observed effects. Significant negative effects on survival, development time, and growth were detected at 6.07, 6.07 and 2.97 microg U g(-1) dry wt, respectively. An LC20 of 2.49 microg U g(-1) dry wt (95% CI=1.48-4.27), and an LC50 of 5.30 microg U g(-1) dry wt (95% CI=3.94-7.25) were estimated. With respect to effects of uranium on larvae mouthpart deformities, we found that the lower the concentrations, the higher the deformity rates. These results highlight the potential impact of uranium at population level in environmentally realistic concentrations.     

Lichen colonization in the city of Turin (N Italy) based on current and historical data

The results of a study carried out to assess current environmental quality by the diversity of epiphytic lichens in the urban area of Turin (N Italy), and comparison with historical data spanning over a period of 200 years, are presented. Lichen assemblages over different time periods are related to changes in environmental conditions and the present situation is improving, as shown by increased numbers of both species and thalli in the city. Today, NO(x) and total suspended particles are the main air pollutants affecting lichen diversity.