Na Yao

Chinese Research Academy of Environmental Sciences, Peping, Beijing, China

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Publications (4)6.68 Total impact

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    H Hou · N Yao · J N Li · Y Wei · L Zhao · J Zhang · F S Li
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    ABSTRACT: Antimony (Sb) distribution, solubility and mobility onto natural soils of China were studied in lysimeter and batch experiments as a function of physicochemical properties of the soil. An outdoor lysimeter experiment investigated the leaching and migration of Sb in the soils with Sb-polluted topsoil and unpolluted subsoil over a 5month period. Soil solutions were collected by suction cups installed at different depth of lysimeters, and leachates were regularly collected and analyzed for Sb concentrations. The majority of the added Sb was retained in the topsoil layers, but small portions were moved to the sub-layers. Sb concentrations in the soil solutions and leachates ranged from 0-755.5 (6.38±54 on average) μgl(-1) and 0-0.45 (smaller than the detection limit) μgl(-1) respectively, indicating the low solubility of Sb in the soils. Batch experiments were performed in order to determine the sorption capacity and the partition coefficient (Kd). Freundlich isotherm described properly the equilibrium experimental data and results show that the Kd values for Primosol, Isohumosol, Ferrosol equal to 22.5, 87.8, 704Lkg(-1), respectively. These results showed the strong capacity of the soils to retain Sb, and prevent it being leached down the profile. The mobilizable Sb was in the order: Primosol>Isohumosol>Ferrosol. Sb migration in the soils was mainly associated with the exchangeable, carbonate-bound, and metal-organic complex-bound fractions. Health risk assessment indicates that Sb leaching from Ferrosol will not harm to human health through groundwater under the test conditions, while it has certain health risks from the Isohumosol and Primosol.
    Full-text · Article · Aug 2013 · Chemosphere
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    ABSTRACT: A laboratory repacked soil-leaching column experiment was conducted to study the effects of simulated acid rain or EDTA by themselves or in combination, on migration and chemical speciation distribution of Pb and its alternative rare metals including Ag, Bi, In, Sb, and Sn. Experimental results demonstrate that leaching with simulated acid rain promoted the migration of Bi, In and Pb, and their migration reached down to 8cm in the soil profile, no enhancement of Sb, Ag or Sn migration was observed. Addition of EDTA significantly enhanced the migration of all six metals, especially Bi, In and Pb. The migration of metals was in the order Pb>Bi>In>Sb>Sn>Ag. The individual and combined effects of acid rain and EDTA increased the environmental risk of metals, by increasing the soluble content of metals in soil solutions and the relative distribution of the exchangeable fraction. Leaching risks of Bi, In and Pb were higher than other three metals.
    No preview · Article · Aug 2012 · Chemosphere
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    ABSTRACT: Soil profile samples of isohumosol, primosol, and ferrosol were obtained in relatively clean areas of China. Concentrations and chemical speciation of rare metals [e.g., Ag (Silver), Bi (Bismuth), In (Indium) and Sn (Tin)] were determined, in which sequential extraction was used to fraction metals. Vertical distributions of elemental enrichment ratios (ERs) were used to study the anthropogenic influence. The mobility of metals was characterized by the sum of exchangeable form and carbonate-bound form. Average concentrations of Ag, Bi, In and Sn in the A horizon were (0.14 +/- 0.01), (0.49 +/- 0.09), (0.050 +/- 0.01), and (2.8 +/- 0.9) mg x kg(-1), respectively. The ERs were close to 1. Average distributions of metal speciation were: Ag, residual (65.8%) > H202-extractable organically bound (H2O2-Org) (25.9%) > Amorphous metal oxide-bound (am-MeOx) (4.2%) > Metal-organic complex-bound (Me-Org) approximately Crystalline Fe oxide-bound (cr-FeOx) (2.0%); Bi, residual (29.2%) > H2O2-Org (27.1%) > cr-FeOx (22.7%) > am-MeOx (18.8%) > Me-Org (1.0%) > carbonate-bound (0.9%) > easily reducible metal oxide-bound (re-MeOx) (0.3%); In, residual (67.8%) > cr-FeOx (17.0%) > am-MeOx (6.8%) > H2O2-Org (6.0%) > carbonate-bound (1.4%) > Me-Org (1.0%); Sn, residual (58.1%) > am-MeOx (23.0%) > cr-FeOx (15.6%) > H2O2-Org (1.8%) > Me-Org (1.1%) > exchangeable approximately carbonate-bound (0.2%). the results indicated that the exogenous elements enrichment was deficiency to minimal, and the concentrations of the rare metals were close to background values of soil in studied areas. Rare metals were stable in soils. The mobility of metals was in the order In > Bi > Sn > Ag.
    No preview · Article · May 2011 · Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.]
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    ABSTRACT: The batch equilibration experiments were carried out to study the adsorption characteristics of Ag+ and the effect of pH on the adsorption process in two typical Chinese soils, which the phaeozem from Northeast China and the red soil from Hunan province. The species transformation of Ag+ was investigated in the experiments using the sequential extraction method. The results showed that an adsorption quantity of Ag+ for both soils increased with increasing solutions initial pH. Adsorption quantity of Ag+ in the two soils also increased with increasing of initial Ag+ concentration in the range from 0 to 100 mg x L(-1), specifically, going up quickly in the concentration range of 0-20 mg x L(-1), but increased gently when Ag+ concentration exceeded 20 mg x L(-1). The Ag+ adsorption data of both soils were adequately described by Langmuir isotherm occurred in Ag+ sorption processes, their maximum adsorption quantities were 250 mg x kg(-1) the phaeozem soil and 88.5 mg x kg(-1) in the red soil, indicating a much higher adsorption capacity in northeast phaeozem soil than that of Hunan red soil. The two soils had similar adsorption kinetic characteristics, with respect to quickly reaching equilibrium within 30 minutes, but the adsorption rate of phaeozem soil was significantly greater than that of the red soil. The species analysis of Ag showed that exchangeable Ag and residual Ag increased in red soil, and metal-organic complex-bound Ag, exchangeable Ag, carbonate-bound Ag and residual Ag increased in phaeozem, respectively.
    No preview · Article · Apr 2010 · Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.]