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Gert Dudel - One of the best experts on this subject based on the ideXlab platform.
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resource manipulation in uranium and arsenic attenuation by lemna gibba l duckweed in Tailing Water of a former uranium mine
Water Air and Soil Pollution, 2005Co-Authors: Martin Mkandawire, Barbara Taubert, Gert DudelAbstract:Influences of phosphorus and nitrogen on uranium and arsenic accumulation in Lemna gibba L. were investigated in the laboratory hydroponic cultures and in the field pot experiments. The initial uranium and arsenic concentrations in solutions for the hydroponic cultures were 1000 μ g l−1 each, while in situ trials used Tailing Water containing 198.7 ± 20.0 μ g U l−1 and 75.0 ± 0.4 μ g As l−1 at a former uranium mine in eastern Germany. A test of three PO43− concentrations (0.01, 13.6 and 40.0 mg l−1) in the hydroponic cultures, highest uranium accumulated in L. gibba under the culture with highest PO43−. Significant differences in uranium accumulation were between 0.01 mg l−1 and 13.6 mg l−1 PO43− cultures only (ANOVA p = 0.05). In the field, addition of 40.0 mg l−1 PO43− increased the bioaccumulation of uranium significantly. Contrary, high PO43− concentrations suppressed the bioaccumulation of arsenic in both the laboratory and the field. The bioaccumulation of both uranium and arsenic increased slightly with the increase of NH4+ concentration. However, high NH4+ concentrations reduced the yield in the control experiments. The concentration of uranium rose temporarily to 856.0 ± 294.0 μ g l−1, while the concentration of arsenic sunk slightly and temporarily immediately after amending the Tailing Waters with 40 mg l−1 PO43−. The speciation of uranium in the Tailing Water was modelled with geochemical code PhreeqC, which predicted that uranyl carbonate species dominated before addition of phosphates, but after increasing the PO43− concentrations, uranyl phosphates species became dominant. Addition of NH4+ to the Tailing Water had negligible influence on free available uranium and arsenic concentrations. Thus, manipulations to enhance uranium and arsenic attenuation by L. gibba has limitation when the amendments interact with other elements including the contaminants in the milieu, and when the target contaminants have antagonistic behaviour in the Tailing Water.
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assignment of lemna gibba l duckweed bioassay for in situ ecotoxicity assessment
Aquatic Ecology, 2005Co-Authors: Martin Mkandawire, Gert DudelAbstract:To narrow the differences between the results obtained from radionuclides and heavy metal ecotoxicity investigations in the laboratory and in the abandoned uranium mines, a few standardised plant bioassay procedures were selected from the literature for testing with Lemna gibba L. The bioassay procedures were tested in situ and ex situ. The laboratory culturing was performed in batch and semicontinuous modes. The results revealed that most of the standardised plant bioassay procedures require modification for the L. gibba bioassay to predict the actual effects under field conditions. L. gibba performed relatively better in the field than laboratory batch cultures despite that the batch cultures had many-fold higher nutrient concentrations than in the field. For instance, the phosphorus concentration of the mine Tailing Water was 0.13 ± 0.09 μg l−1 in the field, while the literature range for phosphorus in the laboratory culture media is 13.6–40 mg l−1. L. gibba growth in the laboratory batch culture was influenced by speciation changes due to consumption of nutrients, CO2 and O2 phase exchanges, and excretion of organic substances by the test plants. Semicontinuous culture modes performed significantly better than batch cultivation even after 10× dilution of the nutrient solution. The growth behaviour revealed that L. gibba exhibited intrapopulation and probiotic interaction for best performance. Growth performance of L. gibba was influenced by the anions that balanced essential cations despite equal cation concentration in the culture media; e.g., the best growth was observed in culture media that had more SO42− than Cl−. Water samples from the field had higher SO42− concentrations than Cl−. The test vessel material, sterilisation and axenic culturing procedures also influenced the sensitivity of the bioassay. These, for instance, and a few others are neither described nor reported in most standard Lemna tests or the literature. Thus, this work presents results of a series of tests conducted on the selected methods. Common and possible errors and corrective measures in assigning L. gibba bioassay from laboratory population levels to field community levels are discussed.
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accumulation of arsenic in lemna gibba l duckweed in Tailing Waters of two abandoned uranium mining sites in saxony germany
Science of The Total Environment, 2005Co-Authors: Martin Mkandawire, Gert DudelAbstract:Accumulation of arsenic in Lemna gibba L. was investigated in Tailing Waters of abandoned uranium mine sites, following the hypothesis that arsenic poses contamination risks in post uranium mining in Saxony, Germany. Consequently, macrophytes growing in mine Tailing Waters accumulate high amounts of arsenic, which might be advantageous for biomonitoring arsenic transfer to higher trophic levels, and for phytoremediation. Water and L. gibba sample collected from pond on Tailing dumps of abandoned mine sites at Lengenfeld and Neuensalz-Mechelgrun were analysed for arsenic. Laboratory cultures in nutrient solutions modified with six arsenic and three PO43− concentrations were conducted to gain insight into the arsenic–L. gibba interaction. Arsenic accumulation coefficients in L. gibba were 10 times as much as the background concentrations in both Tailing Waters and nutrient solutions. Arsenic accumulations in L. gibba increased with arsenic concentration in the milieu but they decreased with phosphorus concentration. Significant reductions in arsenic accumulation in L. gibba were observed with the addition of PO43− at all six arsenic test concentrations in laboratory experiments. Plant samples from laboratory trials had on average twofold higher bioaccumulation coefficients than Tailing Water at similar arsenic concentrations. This would be attributed to strong interaction among chemical components, and competition among ions in natural aquatic environment. The results of the study indicate that L. gibba can be a preliminary bioindicator for arsenic transfer from substrate to plants and might be used to monitor the transfer of arsenic from lower to higher trophic levels in the abandoned mine sites. There is also the potential of using L. gibba L. for arsenic phytoremediation of mine Tailing Waters because of its high accumulation capacity as demonstrated in this study. Transfer of arsenic contamination transported by accumulations in L. gibba carried with flowing Waters, remobilisation through decay, possible methylisation and volatilisation by L. gibba need to be considered.
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capacity of lemna gibba l duckweed for uranium and arsenic phytoremediation in mine Tailing Waters
International Journal of Phytoremediation, 2004Co-Authors: Martin Mkandawire, Barbara Taubert, Gert DudelAbstract:ABSTRACT The potential of Lemna gibba L. to clean uranium and arsenic contamination from mine surface Waters was investigated in wetlands of two former uranium mines in eastern Germany and in laboratory hydroponic culture. Water and plants were sampled and L. gibba growth and yield were monitored in Tailing ponds from the field study sites. Contaminant accumulation, growth and yield experiments were conducted in the laboratory using synthetic Tailing Water. Mean background concentrations of the surface Waters were 186.0 ± 81.2 μg l−1 uranium and 47.0 ± 21.3 μg l−1 arsenic in Site one and 293.7 ± 121.3 μg l−1 uranium and 41.37 ± 24.7 μg l−1 arsenic in Site two. The initial concentration of both uranium and arsenic in the culture solutions was 100 μg l−1. The plant samples were either not leached, leached with deionized H2O or ethylenediaminetetracetic (EDTA). The results revealed high bioaccumulation coefficients for both uranium and arsenic. Uranium and arsenic content of L. gibba dry biomass of the field...
Martin Mkandawire - One of the best experts on this subject based on the ideXlab platform.
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resource manipulation in uranium and arsenic attenuation by lemna gibba l duckweed in Tailing Water of a former uranium mine
Water Air and Soil Pollution, 2005Co-Authors: Martin Mkandawire, Barbara Taubert, Gert DudelAbstract:Influences of phosphorus and nitrogen on uranium and arsenic accumulation in Lemna gibba L. were investigated in the laboratory hydroponic cultures and in the field pot experiments. The initial uranium and arsenic concentrations in solutions for the hydroponic cultures were 1000 μ g l−1 each, while in situ trials used Tailing Water containing 198.7 ± 20.0 μ g U l−1 and 75.0 ± 0.4 μ g As l−1 at a former uranium mine in eastern Germany. A test of three PO43− concentrations (0.01, 13.6 and 40.0 mg l−1) in the hydroponic cultures, highest uranium accumulated in L. gibba under the culture with highest PO43−. Significant differences in uranium accumulation were between 0.01 mg l−1 and 13.6 mg l−1 PO43− cultures only (ANOVA p = 0.05). In the field, addition of 40.0 mg l−1 PO43− increased the bioaccumulation of uranium significantly. Contrary, high PO43− concentrations suppressed the bioaccumulation of arsenic in both the laboratory and the field. The bioaccumulation of both uranium and arsenic increased slightly with the increase of NH4+ concentration. However, high NH4+ concentrations reduced the yield in the control experiments. The concentration of uranium rose temporarily to 856.0 ± 294.0 μ g l−1, while the concentration of arsenic sunk slightly and temporarily immediately after amending the Tailing Waters with 40 mg l−1 PO43−. The speciation of uranium in the Tailing Water was modelled with geochemical code PhreeqC, which predicted that uranyl carbonate species dominated before addition of phosphates, but after increasing the PO43− concentrations, uranyl phosphates species became dominant. Addition of NH4+ to the Tailing Water had negligible influence on free available uranium and arsenic concentrations. Thus, manipulations to enhance uranium and arsenic attenuation by L. gibba has limitation when the amendments interact with other elements including the contaminants in the milieu, and when the target contaminants have antagonistic behaviour in the Tailing Water.
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assignment of lemna gibba l duckweed bioassay for in situ ecotoxicity assessment
Aquatic Ecology, 2005Co-Authors: Martin Mkandawire, Gert DudelAbstract:To narrow the differences between the results obtained from radionuclides and heavy metal ecotoxicity investigations in the laboratory and in the abandoned uranium mines, a few standardised plant bioassay procedures were selected from the literature for testing with Lemna gibba L. The bioassay procedures were tested in situ and ex situ. The laboratory culturing was performed in batch and semicontinuous modes. The results revealed that most of the standardised plant bioassay procedures require modification for the L. gibba bioassay to predict the actual effects under field conditions. L. gibba performed relatively better in the field than laboratory batch cultures despite that the batch cultures had many-fold higher nutrient concentrations than in the field. For instance, the phosphorus concentration of the mine Tailing Water was 0.13 ± 0.09 μg l−1 in the field, while the literature range for phosphorus in the laboratory culture media is 13.6–40 mg l−1. L. gibba growth in the laboratory batch culture was influenced by speciation changes due to consumption of nutrients, CO2 and O2 phase exchanges, and excretion of organic substances by the test plants. Semicontinuous culture modes performed significantly better than batch cultivation even after 10× dilution of the nutrient solution. The growth behaviour revealed that L. gibba exhibited intrapopulation and probiotic interaction for best performance. Growth performance of L. gibba was influenced by the anions that balanced essential cations despite equal cation concentration in the culture media; e.g., the best growth was observed in culture media that had more SO42− than Cl−. Water samples from the field had higher SO42− concentrations than Cl−. The test vessel material, sterilisation and axenic culturing procedures also influenced the sensitivity of the bioassay. These, for instance, and a few others are neither described nor reported in most standard Lemna tests or the literature. Thus, this work presents results of a series of tests conducted on the selected methods. Common and possible errors and corrective measures in assigning L. gibba bioassay from laboratory population levels to field community levels are discussed.
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accumulation of arsenic in lemna gibba l duckweed in Tailing Waters of two abandoned uranium mining sites in saxony germany
Science of The Total Environment, 2005Co-Authors: Martin Mkandawire, Gert DudelAbstract:Accumulation of arsenic in Lemna gibba L. was investigated in Tailing Waters of abandoned uranium mine sites, following the hypothesis that arsenic poses contamination risks in post uranium mining in Saxony, Germany. Consequently, macrophytes growing in mine Tailing Waters accumulate high amounts of arsenic, which might be advantageous for biomonitoring arsenic transfer to higher trophic levels, and for phytoremediation. Water and L. gibba sample collected from pond on Tailing dumps of abandoned mine sites at Lengenfeld and Neuensalz-Mechelgrun were analysed for arsenic. Laboratory cultures in nutrient solutions modified with six arsenic and three PO43− concentrations were conducted to gain insight into the arsenic–L. gibba interaction. Arsenic accumulation coefficients in L. gibba were 10 times as much as the background concentrations in both Tailing Waters and nutrient solutions. Arsenic accumulations in L. gibba increased with arsenic concentration in the milieu but they decreased with phosphorus concentration. Significant reductions in arsenic accumulation in L. gibba were observed with the addition of PO43− at all six arsenic test concentrations in laboratory experiments. Plant samples from laboratory trials had on average twofold higher bioaccumulation coefficients than Tailing Water at similar arsenic concentrations. This would be attributed to strong interaction among chemical components, and competition among ions in natural aquatic environment. The results of the study indicate that L. gibba can be a preliminary bioindicator for arsenic transfer from substrate to plants and might be used to monitor the transfer of arsenic from lower to higher trophic levels in the abandoned mine sites. There is also the potential of using L. gibba L. for arsenic phytoremediation of mine Tailing Waters because of its high accumulation capacity as demonstrated in this study. Transfer of arsenic contamination transported by accumulations in L. gibba carried with flowing Waters, remobilisation through decay, possible methylisation and volatilisation by L. gibba need to be considered.
-
capacity of lemna gibba l duckweed for uranium and arsenic phytoremediation in mine Tailing Waters
International Journal of Phytoremediation, 2004Co-Authors: Martin Mkandawire, Barbara Taubert, Gert DudelAbstract:ABSTRACT The potential of Lemna gibba L. to clean uranium and arsenic contamination from mine surface Waters was investigated in wetlands of two former uranium mines in eastern Germany and in laboratory hydroponic culture. Water and plants were sampled and L. gibba growth and yield were monitored in Tailing ponds from the field study sites. Contaminant accumulation, growth and yield experiments were conducted in the laboratory using synthetic Tailing Water. Mean background concentrations of the surface Waters were 186.0 ± 81.2 μg l−1 uranium and 47.0 ± 21.3 μg l−1 arsenic in Site one and 293.7 ± 121.3 μg l−1 uranium and 41.37 ± 24.7 μg l−1 arsenic in Site two. The initial concentration of both uranium and arsenic in the culture solutions was 100 μg l−1. The plant samples were either not leached, leached with deionized H2O or ethylenediaminetetracetic (EDTA). The results revealed high bioaccumulation coefficients for both uranium and arsenic. Uranium and arsenic content of L. gibba dry biomass of the field...
Shuming Wen - One of the best experts on this subject based on the ideXlab platform.
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effects of cations anions in recycled Tailing Water on cationic reverse flotation of iron oxides
Minerals, 2019Co-Authors: Min Tang, Shuming WenAbstract:It is well known that reverse flotation performance of iron oxides is affected by Water quality. Since many potential variations among Water sources recycling in a mineral processing plant bring unpredictable effects on the flotation system of iron oxides: disturbing ions/compounds, pH, hardness, residual reagents, etc. In this study, the recycled Tailing Water from a local plant, characteristically constituting of Ca2+, Mg2+, Na+, K+, Al3+, Fe3+, Cl−, SO42− etc., was introduced into the cationic reverse flotation process of an iron ore. A series of bench flotation tests using iron ores, micro-flotation tests using pure fine quartz, Water chemical analyses, and zeta potential measurement were conducted with the objective of identifying the possible influences of both cations and anions in the recycled Tailing Water on the flotation performance. The flotation results pointed out that the cation with higher valency had more severe influences on the recovery of iron oxides. The formation of the pH-dependent surface complexes on mineral surfaces, for example, Fe(OH)+, Fe(OH)2+, and Fe(OH)3 resulted from Fe3+ ions adsorption, contributed to the less negative zeta potentials of the quartz, and consequently weakened its interaction with the amine collector. It is worthy to note that SO42− ions seem to have a more positive effect on the recovery of iron oxides than Cl− ions. This is probably attributed to the formation of inner/outer- sphere surface complexes on the iron oxides, inhibiting the dissolution of the iron ions/species, and the coordination with these cations from the recycled Tailing Water, shielding their disturbances in the flotation.
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Effects of Cations/Anions in Recycled Tailing Water on Cationic Reverse Flotation of Iron Oxides
MDPI AG, 2019Co-Authors: Min Tang, Shuming WenAbstract:It is well known that reverse flotation performance of iron oxides is affected by Water quality. Since many potential variations among Water sources recycling in a mineral processing plant bring unpredictable effects on the flotation system of iron oxides: disturbing ions/compounds, pH, hardness, residual reagents, etc. In this study, the recycled Tailing Water from a local plant, characteristically constituting of Ca2+, Mg2+, Na+, K+, Al3+, Fe3+, Cl−, SO42− etc., was introduced into the cationic reverse flotation process of an iron ore. A series of bench flotation tests using iron ores, micro-flotation tests using pure fine quartz, Water chemical analyses, and zeta potential measurement were conducted with the objective of identifying the possible influences of both cations and anions in the recycled Tailing Water on the flotation performance. The flotation results pointed out that the cation with higher valency had more severe influences on the recovery of iron oxides. The formation of the pH-dependent surface complexes on mineral surfaces, for example, Fe(OH)+, Fe(OH)2+, and Fe(OH)3 resulted from Fe3+ ions adsorption, contributed to the less negative zeta potentials of the quartz, and consequently weakened its interaction with the amine collector. It is worthy to note that SO42− ions seem to have a more positive effect on the recovery of iron oxides than Cl− ions. This is probably attributed to the formation of inner/outer- sphere surface complexes on the iron oxides, inhibiting the dissolution of the iron ions/species, and the coordination with these cations from the recycled Tailing Water, shielding their disturbances in the flotation
Min Tang - One of the best experts on this subject based on the ideXlab platform.
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effects of cations anions in recycled Tailing Water on cationic reverse flotation of iron oxides
Minerals, 2019Co-Authors: Min Tang, Shuming WenAbstract:It is well known that reverse flotation performance of iron oxides is affected by Water quality. Since many potential variations among Water sources recycling in a mineral processing plant bring unpredictable effects on the flotation system of iron oxides: disturbing ions/compounds, pH, hardness, residual reagents, etc. In this study, the recycled Tailing Water from a local plant, characteristically constituting of Ca2+, Mg2+, Na+, K+, Al3+, Fe3+, Cl−, SO42− etc., was introduced into the cationic reverse flotation process of an iron ore. A series of bench flotation tests using iron ores, micro-flotation tests using pure fine quartz, Water chemical analyses, and zeta potential measurement were conducted with the objective of identifying the possible influences of both cations and anions in the recycled Tailing Water on the flotation performance. The flotation results pointed out that the cation with higher valency had more severe influences on the recovery of iron oxides. The formation of the pH-dependent surface complexes on mineral surfaces, for example, Fe(OH)+, Fe(OH)2+, and Fe(OH)3 resulted from Fe3+ ions adsorption, contributed to the less negative zeta potentials of the quartz, and consequently weakened its interaction with the amine collector. It is worthy to note that SO42− ions seem to have a more positive effect on the recovery of iron oxides than Cl− ions. This is probably attributed to the formation of inner/outer- sphere surface complexes on the iron oxides, inhibiting the dissolution of the iron ions/species, and the coordination with these cations from the recycled Tailing Water, shielding their disturbances in the flotation.
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Effects of Cations/Anions in Recycled Tailing Water on Cationic Reverse Flotation of Iron Oxides
MDPI AG, 2019Co-Authors: Min Tang, Shuming WenAbstract:It is well known that reverse flotation performance of iron oxides is affected by Water quality. Since many potential variations among Water sources recycling in a mineral processing plant bring unpredictable effects on the flotation system of iron oxides: disturbing ions/compounds, pH, hardness, residual reagents, etc. In this study, the recycled Tailing Water from a local plant, characteristically constituting of Ca2+, Mg2+, Na+, K+, Al3+, Fe3+, Cl−, SO42− etc., was introduced into the cationic reverse flotation process of an iron ore. A series of bench flotation tests using iron ores, micro-flotation tests using pure fine quartz, Water chemical analyses, and zeta potential measurement were conducted with the objective of identifying the possible influences of both cations and anions in the recycled Tailing Water on the flotation performance. The flotation results pointed out that the cation with higher valency had more severe influences on the recovery of iron oxides. The formation of the pH-dependent surface complexes on mineral surfaces, for example, Fe(OH)+, Fe(OH)2+, and Fe(OH)3 resulted from Fe3+ ions adsorption, contributed to the less negative zeta potentials of the quartz, and consequently weakened its interaction with the amine collector. It is worthy to note that SO42− ions seem to have a more positive effect on the recovery of iron oxides than Cl− ions. This is probably attributed to the formation of inner/outer- sphere surface complexes on the iron oxides, inhibiting the dissolution of the iron ions/species, and the coordination with these cations from the recycled Tailing Water, shielding their disturbances in the flotation
Barbara Taubert - One of the best experts on this subject based on the ideXlab platform.
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resource manipulation in uranium and arsenic attenuation by lemna gibba l duckweed in Tailing Water of a former uranium mine
Water Air and Soil Pollution, 2005Co-Authors: Martin Mkandawire, Barbara Taubert, Gert DudelAbstract:Influences of phosphorus and nitrogen on uranium and arsenic accumulation in Lemna gibba L. were investigated in the laboratory hydroponic cultures and in the field pot experiments. The initial uranium and arsenic concentrations in solutions for the hydroponic cultures were 1000 μ g l−1 each, while in situ trials used Tailing Water containing 198.7 ± 20.0 μ g U l−1 and 75.0 ± 0.4 μ g As l−1 at a former uranium mine in eastern Germany. A test of three PO43− concentrations (0.01, 13.6 and 40.0 mg l−1) in the hydroponic cultures, highest uranium accumulated in L. gibba under the culture with highest PO43−. Significant differences in uranium accumulation were between 0.01 mg l−1 and 13.6 mg l−1 PO43− cultures only (ANOVA p = 0.05). In the field, addition of 40.0 mg l−1 PO43− increased the bioaccumulation of uranium significantly. Contrary, high PO43− concentrations suppressed the bioaccumulation of arsenic in both the laboratory and the field. The bioaccumulation of both uranium and arsenic increased slightly with the increase of NH4+ concentration. However, high NH4+ concentrations reduced the yield in the control experiments. The concentration of uranium rose temporarily to 856.0 ± 294.0 μ g l−1, while the concentration of arsenic sunk slightly and temporarily immediately after amending the Tailing Waters with 40 mg l−1 PO43−. The speciation of uranium in the Tailing Water was modelled with geochemical code PhreeqC, which predicted that uranyl carbonate species dominated before addition of phosphates, but after increasing the PO43− concentrations, uranyl phosphates species became dominant. Addition of NH4+ to the Tailing Water had negligible influence on free available uranium and arsenic concentrations. Thus, manipulations to enhance uranium and arsenic attenuation by L. gibba has limitation when the amendments interact with other elements including the contaminants in the milieu, and when the target contaminants have antagonistic behaviour in the Tailing Water.
-
capacity of lemna gibba l duckweed for uranium and arsenic phytoremediation in mine Tailing Waters
International Journal of Phytoremediation, 2004Co-Authors: Martin Mkandawire, Barbara Taubert, Gert DudelAbstract:ABSTRACT The potential of Lemna gibba L. to clean uranium and arsenic contamination from mine surface Waters was investigated in wetlands of two former uranium mines in eastern Germany and in laboratory hydroponic culture. Water and plants were sampled and L. gibba growth and yield were monitored in Tailing ponds from the field study sites. Contaminant accumulation, growth and yield experiments were conducted in the laboratory using synthetic Tailing Water. Mean background concentrations of the surface Waters were 186.0 ± 81.2 μg l−1 uranium and 47.0 ± 21.3 μg l−1 arsenic in Site one and 293.7 ± 121.3 μg l−1 uranium and 41.37 ± 24.7 μg l−1 arsenic in Site two. The initial concentration of both uranium and arsenic in the culture solutions was 100 μg l−1. The plant samples were either not leached, leached with deionized H2O or ethylenediaminetetracetic (EDTA). The results revealed high bioaccumulation coefficients for both uranium and arsenic. Uranium and arsenic content of L. gibba dry biomass of the field...
