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Zheng S.,Zhejiang University | Zheng S.,Agro Environmental Protection Institute | Zheng S.,Key Laboratory of Production Environment and Agro Product Safety | Zheng S.,Tianjin Key Laboratory of Agro Environment and Agro Product Safety | Zhang M.,Zhejiang University
Journal of Environmental Sciences

Sequential extraction procedure was applied to assess the dynamics of solid-phase transformation of added Cu, Pb, Cd, and Hg in a typical Chinese paddy soil incubated under three moisture regimes (75% field capacity, wetting-drying cycle, and flooding). The heavy metals spiked in the soil were time-dependently transferred from the easily extractable fraction (the exchangeable fraction) into less labile fractions (Fe-Mn oxide- and organic matter-bound fractions), and thus reduced lability of the metals. No significant changes were found for the carbonate-bound and residual fractions of the heavy metals in the soil during the whole incubation. Change rate of the mobility factor (MF), a proportion of weakly bound fractions (exchangeable and carbonate-bound) in the total metal of soil, reflected the transformation rate of metal speciation from the labile fractions toward stable fractions. It was found that soil moisture regime did not change the direction and pathways of transformation of metal speciation, but it significantly affected the transformation rate. In general, the paddy soil under flooding regime had higher metal reactivity compared with 75% field capacity and wetting-drying cycle regimes, resulting in the more complete movement of metals toward stable fractions. This might be related to the increased pH, precipitation of the metals with sulfides and higher concentration of amorphous Fe oxides under submerged condition. © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Source

An Y.,Agro Environmental Protection Institute | Zhang K.,Key Laboratory of Production Environment and Agro Product Safety | Dong Q.,Tianjin Key Laboratory of Agro Environment and Agro Product Safety | Zhang L.,Tianjin University
Water Science and Technology

An integrated nitrate treatment using passivated iron powder (PIP) and Alcaligenes eutrophus, which is a kind of hydrogenotrophic denitrifying bacteria, was conducted to investigate the effect of iron oxide coating on final-product distribution in hydrogenotrophic denitrification. Based on the results, the autotrophic denitrification supported by PIP could completely remove about 50 mg·L1 of nitrate within 4 days, and almost 80% of nitrate was changed into N2O (under acetylene blocking) without residual nitrite or ammonium. While only 53% of the nitrate was removed using acid-washed iron (AWI) instead of PIP, about 70% was converted into ammonium. Furthermore, a layer of FeOOH converted from hematite (α-Fe2O3) and magnetite (Fe3O4), which may block direct chemical nitrate reduction, was observed on the iron surface when PIP was used to support hydrogenotrophic denitrification. In addition, increasing pH from 5 to 8 increased nitrite generation from 1.19 to 4.91%, and decreased ammonium formation from 4.23 to 0%. Copyright © IWA Publishing 2013 Water Science and Technology. Source

Li N.,CAS Tianjin Institute of Industrial Biotechnology | Zhao L.,Agro Environmental Protection Institute | Zhao L.,Tianjin Key Laboratory of Agro Environment and Agro Product Safety | Ng T.B.,Chinese University of Hong Kong | And 4 more authors.
Applied Microbiology and Biotechnology

A new molecularly imprinted polymer (MIP), prepared by hispidin as the template molecule, was synthesized and applied as an adsorbent phase for solid phase extraction (SPE) to isolate and enrich hispidin from eight species of mushrooms. The optimization of synthesis and the adsorption behaviors of the MIPs were investigated in detail. In comparison with C18-SPE, MIP-SPE displayed high selectivity and good affinity for hispidin for extract of Phellinus igniarius. The antioxidant activity of the extracts after using the MIPs was evaluated by free radical scavenging activity, and inhibition of erythrocyte hemolysis, and lipid peroxidation. This developed method provided a rapid, selective, and effective approach for separation and enrichment of active compounds from the natural products. © 2015, Springer-Verlag Berlin Heidelberg. Source

Zhang K.,Agro Environmental Protection Institute | Zhang K.,Key Laboratory of Production Environment and Agro Product Safety | Zhang K.,Tianjin Key Laboratory of Agro Environment and Agro Product Safety | An Y.,Agro Environmental Protection Institute | And 6 more authors.

Nano-MgO is a good bactericide but with strong alkalinity in water due to its rapid hydrolysis. To control its hydrolysis rate and keep its bactericidal properties, we synthesized nano-MgO microspheres using chitosan-alginate system in this study. The synthesized nano-MgO release-controlled microspheres (nMgO-RCM) were with 0.98-1.20mm of particle sizes. Also, their embedding ratio and loading percentage was 63.52% and 12.27%, respectively. Based on the characterization results, nano-MgO was only observed on surface of the nMgO-RCM. Its release rate from the nMgO-RCM could be controlled by the chitosan-alginate system, and the observed rate constant (kobs) increased from 0.0289h-1 to 0.0358h-1 with the increment of the dosage from 10mgL-1 to 80mgL-1. Furthermore, the nMgO-RCM could maintain pH value lower than 8.5 and colony counts less than 20CFUmL-1 for at least 120h. © 2012 Elsevier Ltd. Source

Zheng S.-A.,Agro Environmental Protection Institute | Zheng S.-A.,Key Laboratory of Production Environment and Agro Product Safety | Zheng S.-A.,Tianjin Key Laboratory of Agro Environment and Agro Product Safety | Zheng X.,Agro Environmental Protection Institute | And 9 more authors.
Fresenius Environmental Bulletin

Effect of wastewater irrigation on the changes of some soil properties, distribution and fractionation of heavy metals (Cu, Pb and Cd) in soil profiles was investigated by monitoring different plots from Pengzhou, China, which had been irrigated with wastewater for varying periods of time (5, 12 and 20 years, respectively). The non-wastewaterirrigated plot served as the control. Total concentrations of heavy metals at different soil depths were analyzed by acid digestion, and their fractions were partitioned by a sequential extraction procedure, where the speciation of metals was experimentally defined as exchangeable, carbonate-, Fe-Mn oxide-, organic matter-bound and residual fraction. Results showed that soil pH values were significantly (p < 0.05) lowered in plots with more than 12-year irrigation to a depth of 80 cm, while electrical conductivity was elevated for all three plots compared with control, and soil organic matter increased in top 40 cm layers in plots with 12- and 20-year wastewater irrigation. Longterm irrigation with wastewater (12 and 20 years) has led to significant increases in heavy metals' total amounts in surface layer (0-40 cm), in which it also resulted in a marked increase in heavy metal concentrations in the all non-residual fractions, and correspondingly affected the relative binding capacity of heavy metals (except for Pb in soil profile from plot with 20-year irrigation). It was also found that the amounts of heavy metals in residual fractions kept almost unchanged in all plots. The study concludes that long-term wastewater irrigation might give rise to the accumulation and mobilization of heavy metals in upper soil horizons, which may limit the use of wastewater for landscape and agriculture. © by PSP. Source

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