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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 | Year: 2011

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.

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 | Year: 2013

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.

Zhou Q.,Nankai University | Zhou Q.,CAS Shenyang Institute of Applied Ecology | Diao C.,Nankai University | Sun Y.,CAS Shenyang Institute of Applied Ecology | And 3 more authors.
Chemosphere | Year: 2012

The growth, photosynthesis rate, and ultrastructure of Mirabilis jalapa L. as a newly-found remediation species under stress of nitrobenzene (NB) and its uptake and removal of NB by the plants were investigated. The results showed that M. jalapa plants could endure contaminated soils by lower than 10.0mgNBkg -1 because there was no decrease in the total length of the plant roots, the maximum length of the hypocotyle, the length of the first seminal root, the height of the shoots and the dry biomass of the seedlings as well as the photosynthesis rate of the plants compared with those in the control. In particular, the growth of the plants could be significantly (P<0.01) enhanced by 0.1mgNBkg -1 under unautoclaved and autoclaved soils. Ultrastructural observations on leaf cells of the plants found that these cells had smooth, clean and continuous cell membranes and cell walls, indicating that there was no obvious damage by NB in comparison with those in the control. Although the absorption of NB in shoots and roots of M. jalapa was weak, plant-promoted biodegradation of NB was considerable and the dominant contribution in the removal of NB from contaminated soils, suggesting the feasibility of M. jalapa applied to phytoremediation of NB contaminated soils. © 2011 Elsevier Ltd.

Cai Y.,Agro Environmental Protection Institute | Cai Y.,Key Laboratory of Production Environment and Agro Product Safety | Lv J.,East China Institute of Technology | Feng J.,East China Institute of Technology | And 5 more authors.
Spectroscopy Letters | Year: 2012

The analysis of plastics and fibers is of importance to forensic scientists, especially in the investigation of trace evidence. In this study, we use Fourier transform infrared microscope and confocal Raman spectroscope to investigate two kinds of polymers: poly(butylenes adipate-co-terephthalate) and poly(ethylene terephthalate), which are very similar in structure and cannot be discriminated easily with other instruments. Infrared and Raman spectra were tentatively interpreted. The indicative peaks (937cm -1, 1121cm -1 in Infrared spectra; 996cm -1, 1396cm -1 in Raman spectra) to distinguish the two polymers were also summarized. The data in this study can help forensic scientists identify these two polymers accurately and avoid wrong certificate of authenticity. The data also offer the producer and researchers an effective and fast method to characterize and identify the poly(butylenes adipate-co-terephthalate). Copyright © Taylor & Francis Group, LLC.

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.
Chemosphere | Year: 2012

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.

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