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21.
The usefulness of uranium concentration in soil solution or recovered by selective extraction as unequivocal bioavailability indices for uranium uptake by plants is still unclear. The aim of the present study was to test if the uranium concentration measured by the diffusive gradient in thin films (DGT) technique is a relevant substitute for plant uranium availability in comparison to uranium concentration in the soil solution or uranium recovered by ammonium acetate. Ryegrass (Lolium perenne L. var. Melvina) is grown in greenhouse on a range of uranium spiked soils. The DGT-recovered uranium concentration (CDGT) was correlated with uranium concentration in the soil solution or with uranium recovered by ammonium acetate extraction. Plant uptake was better predicted by the summed soil solution concentrations of UO22+, uranyl carbonate complexes and UO2PO4−. The DGT technique did not provide significant advantages over conventional methods to predict uranium uptake by plants. 相似文献
22.
Vink JP 《Environmental pollution (Barking, Essex : 1987)》2009,157(2):519-527
The speciation of heavy metals was measured over a variety of natural and undisturbed water/sediment interfaces. Simultaneously, two benthic species (oligochaete Limnodrilus spp. and the midge Chironomus riparius) were exposed to these sediments. Under occurring redox conditions, free ion activities of trace metals Cd, Cu, Ni, Pb, and Zn were measured with a chelating exchange technique, while geochemical conditions (i.e., redox) remained in tact. Free ion activities were compared with total dissolved concentrations in pore waters and surface waters in order to relate speciation to bioaccumulation. Limnodrilus spp. and C. riparius have accumulation patterns that could be linked to time-dependent exposure concentrations, expressed as chemical speciation, in the surface water and the sediment's pore water. Concentrations of free metal ions in the overlying surface water, rather than in sediment pore water, proved to be the best predictor for uptake. For the first time, measurements are obtained from sediments without disturbing physical-chemical conditions and thus bioavailability, a major restriction of other studies so far. 相似文献
23.
Ikem A Campbell M Nyirakabibi I Garth J 《Environmental monitoring and assessment》2008,140(1-3):69-81
Anthropogenic sources of pollution can significantly contribute to elevated concentrations of toxic elements in soils. A preliminary
survey of trace elements content and their availability in residential soils from New Madrid County, Missouri was undertaken.
Mean elemental concentrations (mg kg−1, dry wt) of sixty two soil samples were: As 6.6, Be 0.8, Cd 1.6, Co 9.7, Cr 24.5, Cu 18.1, Fe 9951, Mn 298, Ni 15.6, Pb 48.8,
V 42.1, Zn 95.5 and Hg 0.05. The US EPA preliminary remediation goals (PRGs) was only exceeded by As (7 % of samples) and
V (8% of samples). The Missouri average background values were exceeded by Pb (69%), Zn (31%), Cu (27%), As (23%), Be (19%),
Co (18%), Ni (16%), V (8%) and Mn (2%). Crustal enrichments (EFc) for As (97), Cr (6), Cu (10), Pb (121), V (7), and Hg (17) were highest for North Lilbourn soils. Fractionation experiment
revealed that Fe (54–79%) was in the residual phase while Zn (70–90%), Mn (88–92%), As (59–81%) and Pb (63–79%) were potentially
available in soils. Factor loadings of the element concentrations on principal components 1, 2 and 3 accounted for over 81%
variance of the data set. The factor loadings suggested that apart from natural contributions of trace elements to the soils,
human activities possibly accounted for other inputs in soils. 相似文献
24.
Jiyan Shi Yu Gao Xiaohan Jiang Hanxin Wu Jianhao Tong Xinyue Ren Jiayu Ren Qianhua Wu Jien Ye Chunhui Li 《环境科学学报(英文版)》2022,120(10):53-62
Penicillium oxalicum SL2 (SL2) is a previously screened Pb-tolerant fungus that can promote crops growth. The relationship between SL2 colonization and Pb immobilization was studied to provide a theoretical basis for microbial remediation of Pb-contaminated paddy soil. In this study, green fluorescent protein (GFP) labeled SL2 was inoculated into different Pb-contaminated paddy soils (S1-S6). The Pb extracted from the soil by HNO3, EDTA and CaCl2 were used to characterize the available Pb. The results showed that the colonization of SL2 was divided into lag phase (0-7 days), growth phase (7-30 days), and mortality phase (30-90 days). SL2 colonized well in sandy soils rich in clay and total phosphorus with initial pH of 4.5-7.0. In addition, SL2 increased soil pH and decreased soil Eh, which was beneficial to immobilize Pb. In different soils, the highest percentages of CaCl2-Pb, EDTA-Pb, and HNO3-Pb immobilized by SL2 were 34.34%-40.53%, 17.05%-20.11%, and 7.39%-15.62%, respectively. Pearson correlation analysis showed that the percentages of CaCl2-Pb and EDTA-Pb immobilized by SL2 were significantly positively correlated with the number of SL2 during the growth phase. SL2 mainly immobilized Pb in the growth phase and a higher peak number of SL2 was beneficial to the immobilization of Pb. 相似文献