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Geochemical fractions of rare earth elements in soil around a mine tailing in Baotou, China.

Wang L, Liang T - Sci Rep (2015)

Bottom Line: The total concentration of REEs in surface soils ranged from 156 to 5.65 × 10(4) mg·kg(-1) with an average value of 4.67 × 10(3) mg·kg(-1), which was significantly higher than the average value in China (181 mg·kg(-1)).We found obvious fractionation of both light and heavy REEs, which was supported by the North American Shale Composite (NASC) and the Post-Archean Average Australian Shale (PAAS) normalized concentration ratios calculated for selected elements (La(N)/Yb(N), La(N)/Sm(N) and Gd(N)/Yb(N)).A slightly positive Ce anomaly and a negative Eu anomaly were also found.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.

ABSTRACT
Rare earth mine tailing dumps are environmental hazards because tailing easily leaches and erodes by water and wind. To assess the influence of mine tailing on the geochemical behavior of rare earth elements (REEs) in soil, sixty-seven surface soil samples and three soil profile samples were collected from different locations near China's largest rare earth mine tailing. The total concentration of REEs in surface soils ranged from 156 to 5.65 × 10(4) mg·kg(-1) with an average value of 4.67 × 10(3) mg·kg(-1), which was significantly higher than the average value in China (181 mg·kg(-1)). We found obvious fractionation of both light and heavy REEs, which was supported by the North American Shale Composite (NASC) and the Post-Archean Average Australian Shale (PAAS) normalized concentration ratios calculated for selected elements (La(N)/Yb(N), La(N)/Sm(N) and Gd(N)/Yb(N)). A slightly positive Ce anomaly and a negative Eu anomaly were also found. For all 14 REEs in soils, enrichment was intensified by the mine tailing sources and influenced by the prevailing wind.

No MeSH data available.


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NASC and PAAS normalized patterns of average REE concentrations in surface soils.
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f6: NASC and PAAS normalized patterns of average REE concentrations in surface soils.

Mentions: To eliminate the Oddo-Harkins effect and characterize the REE signature of soil, the concentrations of individual REEs were normalized to the estimated average composition of REEs in the North American Shale Composite (NASC) and Post-Archean Average Australian Shale (PAAS)32, as shown in Fig. 6. The two shale-normalized REE distribution patterns for soil were generally identical, indicating the consistency of geochemical distribution of REEs in every shale. However, the REE patterns, the curves extending downward from left to right, were characterized by LREE enrichment and HREE depletion. The ratio of LaN/YbN quantifies the inclination of the shale-normalized curves. When the ratio of LaN/YbN is greater than or equal to 1, the curves of LREE incline to right side, meaning that the soil is rich in LREE and low in HREE. The ratio of LaN/YbN was 6.80NASC and 4.59PAAS, meaning that the soil samples around the rare earth mine tailing belong to a LREE soil type intensified by the pollution. Generally, higher concentrations of LREE are observed in soils that developed on phosphate and carbonate rocks, whereas the basalt-weathered soils show enrichment in HREE35. The normalized LREEN/HREEN ratio was 5.01NASC and 3.75PAAS. The ratios of LaN/SmN and GdN/YbN were used to measure the degree of LREE and HREE, respectively. The degree of LREE fractionation, LaN/SmN of 2.08NASC and 1.67PAAS, was slightly higher than that of HREE fractionation, (Gd/Yb)N of 1.48NASC and 1.30PAAS.


Geochemical fractions of rare earth elements in soil around a mine tailing in Baotou, China.

Wang L, Liang T - Sci Rep (2015)

NASC and PAAS normalized patterns of average REE concentrations in surface soils.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4510494&req=5

f6: NASC and PAAS normalized patterns of average REE concentrations in surface soils.
Mentions: To eliminate the Oddo-Harkins effect and characterize the REE signature of soil, the concentrations of individual REEs were normalized to the estimated average composition of REEs in the North American Shale Composite (NASC) and Post-Archean Average Australian Shale (PAAS)32, as shown in Fig. 6. The two shale-normalized REE distribution patterns for soil were generally identical, indicating the consistency of geochemical distribution of REEs in every shale. However, the REE patterns, the curves extending downward from left to right, were characterized by LREE enrichment and HREE depletion. The ratio of LaN/YbN quantifies the inclination of the shale-normalized curves. When the ratio of LaN/YbN is greater than or equal to 1, the curves of LREE incline to right side, meaning that the soil is rich in LREE and low in HREE. The ratio of LaN/YbN was 6.80NASC and 4.59PAAS, meaning that the soil samples around the rare earth mine tailing belong to a LREE soil type intensified by the pollution. Generally, higher concentrations of LREE are observed in soils that developed on phosphate and carbonate rocks, whereas the basalt-weathered soils show enrichment in HREE35. The normalized LREEN/HREEN ratio was 5.01NASC and 3.75PAAS. The ratios of LaN/SmN and GdN/YbN were used to measure the degree of LREE and HREE, respectively. The degree of LREE fractionation, LaN/SmN of 2.08NASC and 1.67PAAS, was slightly higher than that of HREE fractionation, (Gd/Yb)N of 1.48NASC and 1.30PAAS.

Bottom Line: The total concentration of REEs in surface soils ranged from 156 to 5.65 × 10(4) mg·kg(-1) with an average value of 4.67 × 10(3) mg·kg(-1), which was significantly higher than the average value in China (181 mg·kg(-1)).We found obvious fractionation of both light and heavy REEs, which was supported by the North American Shale Composite (NASC) and the Post-Archean Average Australian Shale (PAAS) normalized concentration ratios calculated for selected elements (La(N)/Yb(N), La(N)/Sm(N) and Gd(N)/Yb(N)).A slightly positive Ce anomaly and a negative Eu anomaly were also found.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.

ABSTRACT
Rare earth mine tailing dumps are environmental hazards because tailing easily leaches and erodes by water and wind. To assess the influence of mine tailing on the geochemical behavior of rare earth elements (REEs) in soil, sixty-seven surface soil samples and three soil profile samples were collected from different locations near China's largest rare earth mine tailing. The total concentration of REEs in surface soils ranged from 156 to 5.65 × 10(4) mg·kg(-1) with an average value of 4.67 × 10(3) mg·kg(-1), which was significantly higher than the average value in China (181 mg·kg(-1)). We found obvious fractionation of both light and heavy REEs, which was supported by the North American Shale Composite (NASC) and the Post-Archean Average Australian Shale (PAAS) normalized concentration ratios calculated for selected elements (La(N)/Yb(N), La(N)/Sm(N) and Gd(N)/Yb(N)). A slightly positive Ce anomaly and a negative Eu anomaly were also found. For all 14 REEs in soils, enrichment was intensified by the mine tailing sources and influenced by the prevailing wind.

No MeSH data available.


Related in: MedlinePlus