Strong Accumulators Research Articles

Environmental Impact of Cadmium in a Volcanic Archipelago: Research Challenges Related to a Natural Pollution Source

Cadmium (Cd) is a highly toxic heavy metal particularly susceptible to mobilization by anthropogenic and natural processes. The volcanic nature of oceanic islands in the Macaronesia geographical region such as the Azores archipelago, located near the Mid-Atlantic Ridge, is reflected in deep-sea and shallow-water hydrothermal activities that release heavy metals such as Cd to seawater, affecting marine organisms and integrating food webs. In this paper, a thorough systematic review of all studies performed on coastal marine species in Macaronesia focusing on Cd was conducted, specifically considering the Azorean geological setting and socioeconomic context. Present results are compared and discussed with data from the Mediterranean, a region with apparent strong anthropogenic pollution. The Azorean marine species seem to be particularly strong Cd accumulators, displaying high levels that should be closely monitored, reflecting an important local natural source that should not be underestimated; especially considering the high consumption rates of some of these organisms, which may lead to a potential seafood safety issue. In light of these findings, the potential effects, impacts, and future research challenges are discussed, from an ecological and public health perspective.

Performance of bees and beehive products as indicators of elemental tracers of atmospheric pollution in sites of the Rome province (Italy)

In this survey, we studied the levels of relevant atmospheric elements well known as tracers of vehicular traffic (i.e., Cu, Sb, Sn, Fe, Mn); biomass burning (i.e., K, Rb, Cs, Li, Tl); and soil resuspension (Si, Al, Ca, Ti) in bees and beehive products (honey, wax, pollen, propolis) in five selected sites in the Rome province (Italy). To attentively support the sustainable management of the involved ecosystems, we have enhanced the information variety endowment (fourteen elements, up to 454 samples, five sites, about thirteen thousand analytical determinations) by six sampling campaigns conducted in a one-year survey (2018–2019). The control charts of the considered elements were built for the first time, employing Johnson's probabilistic method in the Rome province area. Thus, we have measured the metal concentration overlap ranges in the selected biomonitor/indicators (as well as medians and distribution) and the overlap bioaccumulation index (OBI) with respect to the lowest (OBI-Lower) and the highest (OBI-Upper) extreme values of the overlap elements’ concentration ranges. The advantage of the OBI is that we can build the control charts by considering the extremes of the bioaccumulation curves of the elements in the matrices simultaneously, thus creating a ranking among the biomonitor/indicators. This study strongly confirms the selected biomonitor/indicators' ability (excluding honey) to reflect the atmospheric deposition of environmental tracers of traffic, biomass burning, and soil in the area of Rome province. Bees and wax resulted in being very strong accumulators of environmental tracers (i.e., Cu, Sn, Mn for traffic; K, Rb, Cs, and Li for biomass burning; and Al, a soil tracer), showing high OBI-U values. For instance, bees have high bioaccumulation surplus with OBI-U values of 68.6 and 92.7 for Cu and Mn, respectively. This confirms their ability as excellent biomonitors when assessing different environmental contamination cases becomes necessary. To a lesser extent, pollen and propolis showed high levels for several tracers for OBI-U and OBI-L values. Honey often showed a univocal bioaccumulation pattern with high OBI-L values (i.e., 53.7; 154.4; and 112.0 for Cu, Fe, and Mn, respectively), indicating the low transfer capability of contaminants from the environment to the final food product, and confirming its good quality. This further confirms that honey is not appropriate as an environmental indicator. Eventually, the OBI-L index can be applied as an early warning signal when the contamination process is in its initial stages. The OBI index boosts the observer's information variety about the performance of bees, wax, pollen, and propolis as element biomonitors in atmospheric ecosystems.

Halogens in Seaweeds: Biological and Environmental Significance

Many marine algae are strong accumulators of halogens. Commercial iodine production started by burning seaweeds in the 19th century. The high iodine content of certain seaweeds has potential pharmaceutical and nutritional applications. While the metabolism of iodine in brown algae is linked to oxidative metabolism, with iodide serving the function of an inorganic antioxidant protecting the cell and thallus surface against reactive oxygen species with implications for atmospheric and marine chemistry, rather little is known about the regulation and homoeostasis of other halogens in seaweeds in general and the ecological and biological role of marine algal halogenated metabolites (except for organohalogen secondary metabolites). The present review covers these areas, including the significance of seaweed-derived halogens and of halogens in general in the context of human diet and physiology. Furthermore, the understanding of interactions between halogenated compound production by algae and the environment, including anthropogenic impacts, effects on the ozone layer and global climate change, is reviewed together with the production of halogenated natural products by seaweeds and the potential of seaweeds as bioindicators for halogen radionuclides.

Evolution of dust in protoplanetary disks of eruptive stars

Aims. Luminosity bursts in young FU Orionis-type stars warm up the surrounding disks of gas and dust, thus inflicting changes on their morphological and chemical composition. In this work, we aim at studying the effects that such bursts may have on the spatial distribution of dust grain sizes and the corresponding spectral index in protoplanetary disks. Methods. We use the numerical hydrodynamics code FEOSAD, which simulates the co-evolution of gas, dust, and volatiles in a protoplanetary disk, taking dust growth and back reaction on gas into account. The dependence of the maximum dust size on the water ice mantles is explicitly considered. The burst is initialized by increasing the luminosity of the central star to 100–300 L⊙ for a time period of 100 yr. Results. The water snowline shifts during the burst to a larger distance, resulting in the drop of the maximum dust size interior to the snowline position because of more efficient fragmentation of bare grains. After the burst, the water snowline shifts quickly back to its preburst location followed by renewed dust growth. The timescale of dust regrowth after the burst depends on the radial distance so that the dust grains at smaller distances reach the preburst values faster than the dust grains at larger distances. As a result, a broad peak in the radial distribution of the spectral index in the millimeter dust emission develops at ≈10 au, which shifts further out as the disk evolves and dust grains regrow to preburst values at progressively larger distances. This feature is most pronounced in evolved axisymmetric disks rather than in young gravitationally unstable counterparts, although young disks may still be good candidates if gravitational instability is suppressed. We confirmed our earlier conclusion that spiral arms do not act as strong dust accumulators because of the Stokes number dropping below 0.01 within the arms, but this trend may change in low-turbulence disks. Conclusions. We argue that, depending on the burst strength and disk conditions, a broad peak in the radial distribution of the spectral index can last for up to several thousand years after the burst has ended and can be used to infer past bursts in otherwise quiescent protostars. The detection of a similar peak in the disk around V883 Ori, an FU Orionis-type star with an unknown eruption date, suggests that such features may be common in the post-outburst objects.

Manganese accumulation and tissue-level distribution in Australian Macadamia (Proteaceae) species

Background and aimsAustralian Macadamia species are known for their edible nuts as well as their ability to take up high concentrations of manganese (Mn) into their leaves. However, little is known about the ecophysiology of Mn in species of Macadamia. MethodsThis study investigated (i) Mn accumulation in wild Macadamia using handheld X-ray fluorescence spectroscopy (XRF) of herbarium collections, and (ii) Mn uptake in three out of four known Macadamia species (M. tetraphylla, M. integrifolia and M. ternifolia) in a pot experiment that delivered Mn treatments in both solid (as natural Mn-minerals mixed with quartz sand) and liquid form (as MnSO4 solution added to soil). Tissue samples were analysed for bulk elemental concentrations and for in vivo distribution of Mn and other elements using laboratory μXRF analysis. Key resultsThe results revealed that wild M. ternifolia and M. integrifolia are strong Mn accumulators with up to 9600 μg Mn g−1 and 8500 μg Mn g-1, respectively, followed by M. jansenii (6400 μg Mn g-1) and M. tetraphylla (5100 μg Mn g-1). Under the controlled conditions, high Mn accumulation was demonstrated for M. integrifolia and M. tetraphylla with greater than 7500 μg Mn g−1 in mature leaves in the highest Mn treatment level. Our results further showed that Mn was efficiently translocated from the roots to the shoots with translocation factor >1 in the studied species. The laboratory μXRF analysis revealed that Mn was absent from the vascular bundles and concentrated in the areas between veins. ConclusionsAll the four Macadamia species have high foliar Mn concentrations qualifying them as strong Mn accumulators in nature as determined by handheld XRF analysis of herbarium specimens. Under experimental conditions, M. integrifolia and M. tetraphylla were confirmed to be strong Mn accumulators. Manganese was shown by laboratory μXRF analysis to be concentrated in the inter-veinal areas of the leaf lamina.

Accumulation of Potentially Toxic Elements in Viola L. (Sect. Melanium Ging.) from the Ultramafic and Non-ultramafic Soils of the Balkan Peninsula

The aim of the present study was to assess the metal concentrations in five species of the genus Viola L. (section Melanium) from 12 ultramafic outcrops and two non-ultramafic (prolluvium and dolomite) soils from Serbia and Bosnia and Herzegovina. The concentrations of P2O5, K2O, Ca, Mg, Fe, Mn, Zn, Cu, Cr, Co, Cd and Pb in soils and plant samples, as well as their shoot-to-root ratio, biological concentration and accumulation factors were determined. Five investigated Viola species growing on 14 different localities displayed considerable differences in concentration of potentially toxic elements in their roots and its accumulation in their shoots. Viola kopaonikensis and V. beckiana from ultramafic soils could be classified as strong Ni accumulators, since moderately high level of Ni was measured in their shoots (up to 266 mg kg−1 and 337 mg kg−1, respectively), while in V. tricolor high amount of the same element was accumulated in the roots (up to 395 mg kg−1). Population of V. beckiana from dolomitic site in Bosnia and Herzegovina accumulated high concentrations of Pb in the shoots (67.1 mg kg−1), as well as of Cd in both roots and shoots (81.1 mg kg−1 and 60.5 mg kg−1). The results also suggest that V. kopaonikensis populations from the ultramafic soils of Serbia emerge as Cr accumulators, which is quite rare trait within the genus Viola. It seems that species from Melanium section apply quite different strategies against toxic elements. Future studies should strive to explain what adaptive mechanisms are hidden behind it.

Assessment of trace element accumulation potential of Noccaea kovatsii from ultramafics of Bosnia and Herzegovina and Serbia.

In this work, we present the results of the investigation of trace elements (Fe, Mg, Ni, Zn, Cu, Cr, Co, Cd, Pb) accumulation potential of Noccaea kovatsii (Heuff.) F. K. Mey., from the Balkan Peninsula. The study included eight populations from ultramafic soils, six from Bosnia and Herzegovina, and two from Serbia. Principal component analysis (PCA) was used to reveal relationships of elements in soil, and Pearson's correlation coefficients for analysing associations of available quantities of elements in soil and those in roots and shoots of N. kovatsii. Uptake and translocation efficiency was assessed by using bioconcentration (BCF) and translocation factors (TF). All the analysed populations of N. kovatsii emerged as strong Ni accumulators, with the highest shoot concentrations of 12,505 mg kg-1. Even thought contents of Zn in plant tissues of N. kovatsii were under the hyperaccumulation level (602 mg kg-1 and 1120 mg kg-1 respectively), BCF was up to 667, indicating that certain surveyed populations have strong accumulative potential for this element.

Assessment of trace elements pollution in the sea ports of New South Wales (NSW), Australia using oysters as bioindicators

In this study Sydney rock oysters (S. glomerata) from six major sea ports of NSW, Australia were used as bioindicators to assess the distribution and levels of trace element accumulation in the ports. Substantial enrichment of Cu, Pb and Zn in the oysters of the sea ports were detected when compared to their background samples and the US Environmental Protection Agency (USEPA) provisional tolerable intake standard. Enrichment of As, Al, Fe, Mn, Br, Sr were also found in the oysters at the port areas. The bioconcentration ratios of the trace elements illustrated significant Fe, Cu, Zn, As, Mn, Al, Pb and Cr accumulation in S. glomerate. The biota sediment accumulation factor suggested Cu, Mn and Zn accumulation at two of the ports (Port Yamba and Botany), indicating availability of these metals in the oysters as strong metal accumulators. In addition, integrated metal contamination illustrated notable Fe, Zn, Cu and Al contamination at port environment, whereas cluster analysis portrayed interconnection between the contaminants and the study sites.

Bioaccumulation of heavy metals in mesozooplankton from a human-impacted south western Atlantic estuary (Argentina)

The total metal concentrations (Cd, Cu, Pb, Zn, Mn, Ni, Cr, and Fe) in the mesozooplankton (200 μm–2 mm) were studied for a year in a human-impacted estuary strongly affected by urban and industrial discharges located in the South Atlantic. Over the last 25 years, this estuary has been the site of significant anthropogenic impacts including industrial activities, maritime traffic, and regular dredging. A quantitative and qualitative analysis was also carried out to identify the mesozooplanktonic community that was sampled for metal determinations. The mesozooplankton had high concentrations of toxic metals such as Cd, Pb, Cr, and Ni, which may indicate that these organisms are strong accumulators of these metals. Also, the analyzed metals had a wide temporal variation, the highest levels being in autumn and spring. The ranges were as follows: cadmium (Cd): 0.3–3.8; copper (Cu): 35.3–226.6; chromium (Cr): 1.4–57.9; iron (Fe): 1060–57370; manganese (Mn): 18–1102; nickel (Ni): 2.8–57.3; lead (Pb): 2.4–66.7; zinc (Zn): 97.6–1872.2 (μg g –1dry weight). Total zooplankton abundance also showed a significant temporal variation and the most important taxa were the copepods Acartia tonsa, Eurytemora americana, the barnacle Balanus spp. (in the nauplius larval stage), and the crab Cyrtograpsus altimanus (in the zoea larval stage).<br/> In zooplankton, all the metals were detected throughout the whole sampling year and at all sampling sites, which suggests the presence of continuous or quasi-continuous sources of these contaminants. Thus, the most abundant zooplankton species could be considered as potential biomonitors for trace metals in heavily impacted marine environments like estuaries.

Surviving Volcanic Environments—Interaction of Soil Mineral Content and Plant Element Composition

Different plant species were investigated from two Aeolian Islands located in close vicinity, one with fumarolic activity (Vulcano) and one without (Lipari). On Vulcano, elevated concentrations of SO2/H2S determined in ambient air indicated the need of plants to adapt to harmful sulphur concentrations by detoxification strategies. The current study was focused on evaluating the element composition of plant leaves in relation to soil mineral contents. The soil of Volcano was characterised by a significantly lower pH on all three sampling sites as well as very high amounts of sulphur and plant available sulphate due to volcanic activities, compared to Lipari. By contrast, a general difference in the composition of trace elements in the soil was not observed between the islands, apart from arsenic, which was increased at all three sampling sites on Vulcano. Element accumulation in the leaves differed between the two islands. The tested species showed a significant higher accumulation of numerous elements (Al, B, Fe, K, Mg, Mn, Ni, and Zn) on Vulcano compared to Lipari, while excluding Ca and Mo. These differences in element accumulation in the leaves between the islands may be caused by the lower soil pH on Vulcano. Extreme sulphur accumulation was found for all tested species on Vulcano, but was lower in woody species with higher dry matter content compared to herbaceous species with lower dry matter content. This caused a significantly negative correlation between plant sulphur and dry matter content. From these results, it is concluded that species with higher dry matter contents possess a more effective protection against extreme sulphur accumulation. Strategies to cope with other potentially toxic elements in the soil ranged from exclusion to hyper-accumulation. Hierarchical cluster analyses of the leaf element content revealed a clear separation between two groups: First, herbaceous perennial plants as strong accumulators; and second, woody perennial plants such as shrubs or trees as less strong accumulators, with the primordial species Fumaria capreolata representing an outside group.

Bioaccumulation of trace metals in farmed pacific oysters Crassostrea gigas from SW Gulf of California coast, Mexico

The aim of the study was to evaluate the bioavailability of trace metals (Chromium, Copper, Nickel, Lead, Zinc, Cadmium, Arsenic, and Mercury) in the commercially consumed Crassostrea gigas oysters collected over a 12-month growth period (2011–12) from an experimental cultivation farm in La Pitahaya, Sinaloa State, Mexico. Sediment and water samples were also collected from four different zones adjacent to the cultivation area to identify the concentration patterns of metals. The results revealed that sewage disposals, fertilizers used for agricultural practices and shrimp culture are the major sources for the enrichment of certain toxic metals. The metal concentrations in oysters presented a decreasing order of abundance (all values in mg Kg−1): Zn (278.91 ± 93.03) > Cu (63.13 ± 31.72) > Cr (22.29 ± 30.23) > Cd (14.54 ± 4.28) > Ni (9.41 ± 11.33) > Pb (2.22 ± 1.33) > As (0.58 ± 0.91) > Hg (0.04 ± 0.06). Bioconcentration Factor (BCF) and Biota Sediment Accumulation Factor (BSAF) exhibited that C. gigas in the region are strong accumulators for Zn and Cd respectively. Thus, the present study proves to fulfill the gap in understanding the rate of bioaccumulation of metals in C. gigas which is regarded as the most sought after oyster species globally.

Bioconcentration Factor (BCF) and Translocation Factor (TF) of Heavy Metals in Mangrove Trees of Blanakan Fish Farm

In the mangroves of Blanakan, Indonesia, silvofishery practices may play a role in maintaining the environmental quality of ponds. Mangroves are known as pollutant traps since their root systems absorb and accumulate materials. Heavy metals are pollutants that often contaminate aquatic environment like ponds. The bioconcentration factor can be used to evaluate the content of heavy metals in organisms, while the translocation factor can be used to measure the amount of heavy metals transferred form one organ to another. The aim of this study was to determine the bioconcentration factor and the translocation factor of heavy metals (Pb, Cu, and Zn) in mangrove trees ( Avicennia and Rhizopora ) at the Blanakan ponds. Samples of mangrove trees from 3 stations, were cut using a knife, and samples of sediments were collected using Ekman Bottom Grab sampler. Samples were then prepared for heavy metal content analysis using the Shimadzu 6300 atomic absorption spectrophotometer. The bioconcentration and translocation factors were calculated using formulas; the bioconcentration factor was calculated as the content of heavy metals in trees divided by the content of heavy metals in sediments. Results showed that the bioconcentration factor of Cu was higher than 1 in the roots, stems and leaves of Avicennia trees and of Zn was higher than 1 in the roots of Rhizopora trees at station 1. Translocation factors higher than 1 were mostly found in Avicennia (Cu) and Rhizopora (Pb) trees. Mangrove trees with translocation values of greater than 1 for one or more heavy metals can be considered as strong accumulators of the corresponding metals.

Natural variation in correlations between cadmium and micronutrients in potato tubers

Tuber cadmium (Cd) accumulation was evaluated in ten potato cultivars grown in the same field with an average soil Cd level of 0.06mgkg−1 dry weight (DW). Analysis of tuber metal levels revealed a significant difference in mean Cd concentrations among different cultivars, which varied from 0.05 to 0.21mgkg−1DW. No cultivars exceeded the maximum permissible concentration (MPC) for Cd in potato. Correlation analysis showed a strong positive relationship between bioaccumulation of Cd and zinc (Zn), copper (Cu) or manganese (Mn). There was also a negative correlation between Cd and iron (Fe) accumulation which was significant only within three cultivars including Summer Delight, Russet Burbank and Agria. Summer Delight, with the lowest Cd and highest Fe content, was identified as a low Cd accumulating cultivar as well as a Fe-enriched tuber vegetable making it of significant interest. Laura, Yukon Gold and Purple Passion were identified as strong Cd accumulators. One of the implications is that growing these three potato cultivars in soils with Cd levels greater than 0.06mgkg−1DW might be of human health concern.

Assessment of Trace Metal Contamination and Accumulation in Sediment and Plants of the Suoxu River, China

Trace metal contamination in aquatic ecosystems is a major environmental problem since their accumulation along the food chain poses a public health risk. In this study, we tried to find whether, and to what extent, native plant species along the Suoxu River, China, may be useful for phytostabilization. The concentration of several metal elements (Cd, Cr, Cu, Ni, Pb and Zn) in sediment and plant samples collected from different sections of the Suoxu River, China was investigated. Results show that the concentrations of trace metals in the sediment and plants are similar and are found in the order of Zn>Cr>Pb>Cu>Ni>Cd. Standing stock concentration varied between plants groups and metals. The bioconcentration factor (BCF) and translocation factor (TrF) values were <1 for most of the trace metals, suggesting that the investigated species are no strong accumulators of trace metals, and that translocation from roots to shoots is low. Our study shows that native plant species growing on contaminated sites may have the potential for phytostabilization but not for phytoremediation.

Differences in trace element profiles of three subspecies of Silene parnassica (Caryophyllaceae) growing on ophiolitic substrate

The aim of the present study was to compare trace element profiles and the differences in uptake and translocation of trace elements in plants from five populations (three from Greece and two from Serbia) belonging to three subspecies of Silene parnassica Boiss. &amp; Sprun. growing on ophiolitic substrates. For comparison of the subspecies, bioconcentration and translocation factors were used, as well as Spearman’s rank correlation coefficients for concentrations of elements in root and shoot samples. Chemical characteristics of the soil samples (pH, organic C, P2O5, K2O, Ca, Fe, Mg, Mn, Ni, Zn, Cu, Cr, Co, Cd and Pb) and plant samples (P2O5, K2O, Ca, Fe, Mg, Mn, Ni, Zn, Cu, Cr, Co, Cd and Pb) were determined, as well as bioconcentration and translocation factors and correlation matrices. All the three subspecies acted as strong Ni accumulators, with equal concentrations of Ni in roots and shoots, the values being several times higher than 100 mg kg–1, exceeding concentrations of available Ni in the soil. Concentrations of Cu and Cr in the aboveground plant tissues in samples from three localities were several times higher than expected, even for plants growing on metalliferous soils, exceeding, by multiple times, the available concentrations in the soil samples.

Different Selective Effects on Rhizosphere Bacteria Exerted by Genetically Modified versus Conventional Potato Lines

BackgroundIn this study, we assessed the actively metabolizing bacteria in the rhizosphere of potato using two potato cultivars, i.e. the genetically-modified (GM) cultivar Modena (having tubers with altered starch content) and the near-isogenic non-GM cultivar Karnico. To achieve our aims, we pulse-labelled plants at EC90 stage with 13C-CO2 and analysed their rhizosphere microbial communities 24 h, 5 and 12 days following the pulse. In the analyses, phospholipid fatty acid/stable isotope probing (PLFA-SIP) as well as RNA-SIP followed by reverse transcription and PCR-DGGE and clone library analysis, were used to determine the bacterial groups that actively respond to the root-released 13C labelled carbonaceous compounds.Methodology/Principal findingsThe PLFA-SIP data revealed major roles of bacteria in the uptake of root-released 13C carbon, which grossly increased with time. Gram-negative bacteria, including members of the genera Pseudomonas and Burkholderia, were strong accumulators of the 13C-labeled compounds at the two cultivars, whereas Gram-positive bacteria were lesser responders. PCR-DGGE analysis of cDNA produced from the two cultivar types showed that these had selected different bacterial, alpha- and betaproteobacterial communities at all time points. Moreover, an effect of time was observed, indicating dynamism in the structure of the active bacterial communities. PCR-DGGE as well as clone library analyses revealed that the main bacterial responders at cultivar Karnico were taxonomically affiliated with the genus Pseudomonas, next to Gluconacetobacter and Paracoccus. Cultivar Modena mainly attracted Burkholderia, next to Moraxella-like (Moraxellaceae family) and Sphingomonas types.Conclusions/SignificanceBased on the use of Pseudomonas and Burkholderia as proxies for differentially-selected bacterial genera, we conclude that the selective forces exerted by potato cultivar Modena on the active bacterial populations differed from those exerted by cultivar Karnico.

Strong accumulators from collision-resistant hashing

Accumulator schemes were introduced in order to represent a large set of values as one short value called the accumulator. These schemes allow one to generate membership proofs, that is, short witnesses that a certain value belongs to the set. In universal accumulator schemes, efficient proofs of non-membership can also be created. Li et al. (Proceedings of applied cryptography and network security--ACNS '07, LNCS, vol 4521, 2007), building on the work of Camenisch and Lysyanskaya (Advances in cryptology--proceedings of Crypto '02, LNCS, vol 2442. Springer, Berlin, pp 61---76, 2002), proposed an efficient accumulator scheme, which relies on a trusted accumulator manager. Specifically, a manager that correctly performs accumulator updates. In this work, we introduce the notion of strong universal accumulator schemes, which are similar in functionality to universal accumulator schemes, but do not assume the accumulator manager is trusted. We also formalize the security requirements for such schemes. We then give a simple construction of a strong universal accumulator scheme, which is provably secure under the assumption that collision-resistant hash functions exist. The weaker requirement on the accumulator manager comes at a price; our scheme is less efficient than known universal accumulator schemes--the size of (non)membership witnesses is logarithmic in the size of the accumulated set in contrast to constant in the scheme of Camenisch and Lysyanskaya. Finally, we show how to use strong universal accumulators to solve a problem of practical relevance, the so-called e-Invoice Factoring Problem.

Plants as bio-monitors for Cs-137, Pu-238, Pu-239,240 and K-40 at the Savannah River Site

The Savannah River Site was constructed in South Carolina to produce plutonium (Pu) in the 1950s. Discharges associated with these now-ceased operations have contaminated large areas within the site, particularly streams associated with reactor cooling basins. Evaluating the exposure risk of contamination to an ecosystem requires methodologies that can assess the bioavailability of contaminants. Plants, as primary producers, represent an important mode of transfer of contaminants from soils and sediments into the food chain. The objective of this study was to identify local area plants for their ability to act as bio-monitors of radionuclides. The concentrations of cesium-137 ((137)Cs), potassium-40 ((40)K), (238)Pu and (239,240)Pu in plants and their associated soils were determined using γ and α spectrometry. The ratio of contamination concentration found in the plant relative to the soil was calculated to assess a concentration ratio (CR). The highest CR for (137)Cs was found in Pinus palustris needles (CR of 2.18). The correlation of soil and plant (137)Cs concentration was strong (0.76) and the R(2) (0.58) from the regression was significant (p = 0.006). This suggests the ability to predict the degree of (137)Cs contamination of a soil through analysis of the pine needles. The (238)Pu and (239,240)Pu concentrations were most elevated within the plant roots. Extremely high CR values were found in Sparganium americanum (bur-reed) roots with a value of 5.86 for (238)Pu and 5.66 for (239,240)Pu. The concentration of (40)K was measured as a known congener of (137)C. Comparing (40)K and (137)C concentrations in each plant revealed an inverse relationship for these radioisotopes. Correlating (40)K and (137)Cs was most effective in identifying plants that have a high affinity for (137)Cs uptake. The P. palustris and S. americanum proved to be particularly strong accumulators of all K congeners from the soil. Some species that were measured, warrant further investigation, are the carnivorous plant Utricularia inflata (bladderwort) and the emergent macrophyte Juncus effusus. For U. inflata, the levels of (137)Cs, (238)Pu, and (239,240)Pu (which were 3922, 8399, and 803 Bq kg(-1), respectively) in the leaves were extremely high. The highest (137)Cs concentration from the study was measured in the J. effusus root (5721 Bq kg(-1)).

Characteristics of nickel accumulation in native plants growing in ultramafic rock areas in Hokkaido

Nickel accumulation in the native plants growing in ultramafic rock areas in Hokkaido, Japan was studied. The mean soil pH ranged from 6.1 to 8.0. The content of exchangeable Ni in the soil was only 3 to 13 mg kg−1. The lowest content of total Ni was 1.3 g kg−1, and the highest value was 2.6 g kg−1. Thlaspi japonicum was found to accumulate as much as 1,045 mg Ni (kg dry wt)−1, although this species is not an ultramafic plant. Five other species, Allium schoenoprasum var. sibutuense, Viola yubariana (endemic species on Mt. Yupari), Lagotis takedana (endemic species on Mt. Yupari), Viola sacchalinensis var. alpina, and Draba japonica were identified as strong Ni accumulators based on measurements using dried herbarium specimens. The Ni content in ultramafic plants exceeded 50 mg (kg dry wt)−1 in about half of the native plants growing in ultramafic rock areas. The Ni content of dried plants of Allium schoenoprasum var. sibutuense was 234 mg (kg dry wt)−1, while that of Allium maximowiczii was only 19 mg (kg dry wt)−1. Although Deschampsia caespitosa var. levis, Japonolirion osense var. saitoi, Betula apo iens is , and Primula hidakana are ultramafic plants, the Ni content in these plants was less than 10 mg (kg dry wt)−1. In all the examined ultramafic plant species, the Ni content in plants plotted against the exchangeable Ni content in soil was represented by a regression curve and not a straight line. The Ni content in plants increased markedly with increasing exchangeable Ni content in soil in a low content range, but slightly in a high content range. In common plants, a similar correlation was observed only in one species, a linear correlation in three species and no correlation in two species.

Mineral content of leaves from trees growing on serpentine soils under contrasting rainfall regimes in Puerto Rico

The interactions between water and soil nutrient availability in determining leaf nutritional composition and structural features were investigated in forests on serpentine in Maricao and Susua (Puerto Rico). These forests grow under contrasting rainfall regimes: Maricao is a wet forest located at altitudes above 500 m and receiving more than 2500 mm rainfall, while Susua is a humid forest located well below 500 m, with less than 1500 mm rainfall and a well defined dry season. Dominant tree species and soils were analysed for N, P, K, Ca, Mg and Ni. Soils can be differentiated according to their K content (higher in Maricao) and P contents (higher in Susua). Mature leaves of both forests have sclerophyllous characteristics as judged from the Specific Leaf Areas (<80 cm2 g-1) and low P contents. Leaf area development is strongly correlated with leaf N and P contents in both forests, but Maricao samples appear to be more limited by P availability. In concordance with soil values, the Susua leaf sample set has significantly higher contents of P, but lower contents of K when compared with the Maricao sample set. Analyses of soluble K, Ca, and Mg reveal strong physiological selectivity in the absorption of these cations. K/Ca and Ca/Mg ratios are markedly higher in the soluble leaf extracts than in the soil extracts. It seems that restriction to vegetation development in the serpentine areas investigated are more related to nutritional deficiencies and not to high contents of either Mg or Ni in the upper soil layers. Only two strong Ni accumulators were found, Cassine xylocarpa (1.2 μmol Ni g-1 dry mass or 70 μg g-1) from Susua, and Chionanthus domingensis (12.2 μmol g-1, or about 700 μg g-1) from Maricao. These species are not restricted to serpentine areas in Puerto Rico.