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Vu Q.D.,Vietnam Institute of Agricultural Sciences | Vu Q.D.,Copenhagen University | De Neergaard A.,Copenhagen University | Tran T.D.,Vietnamese Academy of Agriculture science | And 3 more authors.
Environmental Technology (United Kingdom) | Year: 2014

This study investigated the effects of different mixing ratios of crop residues and biochar with liquid digestate from anaerobically treated pig manure on CH4, CO2, and N2O emissions over 84 days in a system of passive aeration composting, resembling typical Vietnamese solid manure storage conditions. Two treatments with solid manure were included for comparison. The results showed that C losses through CH4 and CO2 emissions accounted for 0.06–0.28% and 1.9–26.7%, respectively, of initial total C. CH4 losses accounted for just 0.4–4.0% of total C losses. Total N losses accounted for 27.1–40% of initial total N in which N2O emissions corresponded to 0.01–0.57% of initial total N, and hence accounted for only 0.1–1.8% of total N losses. It is assumed that the remainder was either the result of denitrification losses to N2 or ammonia volatilization. The composting of biochar (B) or crop residue with digestate (D) showed significantly lower CH4 and N2O emissions compared with composting manure (M) (p < .05). The composting of digestate with biochar showed significantly lower CO2 and CH4 emissions and significantly higher N2O emissions compared to the composting of digestate with rice straw (RS) (p < .05). The combined composting of digestate with biochar and rice straw (D + B + RS5:0.3:1) showed significantly reduced N2O emissions compared with composting digestate with biochar with alone (p < .05). Composting sugar cane bagasse (SC) with digestate (D + SC) significantly reduced CH4 and N2O emissions compared with the composting of rice straw with digestate (D + RS3.5:1 and D + RS5:1) (p < .05). Source


Vu Q.D.,Copenhagen University | De Neergaard A.,Copenhagen University | Tran T.D.,Vietnamese Academy of Agriculture science | Hoang H.T.T.,Vietnamese Academy of Agriculture science | And 2 more authors.
Environmental Technology (United Kingdom) | Year: 2015

This study investigated the effects of different mixing ratios of crop residues and biochar with liquid digestate from anaerobically treated pig manure on CH4, CO2, and N2O emissions over 84 days in a system of passive aeration composting, resembling typical Vietnamese solid manure storage conditions. Two treatments with solid manure were included for comparison. The results showed that C losses through CH4 and CO2 emissions accounted for 0.06-0.28% and 1.9-26.7%, respectively, of initial total C. CH4 losses accounted for just 0.4-4.0% of total C losses. Total N losses accounted for 27.1-40% of initial total N in which N2O emissions corresponded to 0.01-0.57% of initial total N, and hence accounted for only 0.1-1.8% of total N losses. It is assumed that the remainder was either the result of denitrification losses to N2 or ammonia volatilization. The composting of biochar (B) or crop residue with digestate (D) showed significantly lower CH4 and N2O emissions compared with composting manure (M) (p <.05). The composting of digestate with biochar showed significantly lower CO2 and CH4 emissions and significantly higher N2O emissions compared to the composting of digestate with rice straw (RS) (p <.05). The combined composting of digestate with biochar and rice straw (D + B + RS5:0.3:1) showed significantly reduced N2O emissions compared with composting digestate with biochar with alone (p <.05). Composting sugar cane bagasse (SC) with digestate (D + SC) significantly reduced CH4 and N2O emissions compared with the composting of rice straw with digestate (D + RS3.5:1 and D + RS5:1) (p <.05). © 2014 Taylor & Francis. Source


Minh N.D.,Vietnamese Academy of Agriculture science | Hough R.L.,James Hutton Institute | Thuy L.T.,Vietnam Institute of Agricultural Sciences | Nyberg Y.,Swedish University of Agricultural Sciences | And 4 more authors.
Science of the Total Environment | Year: 2012

This study estimates the dietary exposure to cadmium (Cd), and associated potential health risks, for individuals living and working in a metal recycling community (n = 132) in Vietnam in comparison to an agricultural (reference) community (n = 130). Individual-level exposure to Cd was estimated through analysis of staple foodstuffs combined with information from a food frequency questionnaire. Individual-level exposure estimates were compared with published 'safe' doses to derive a Hazard Quotient (HQ) for each member of the study population. Looking at the populations as a whole, there were no significant differences in the diets of the two villages. However, significantly more rice was consumed by working age adults (18-60. years) in the recycling village compared to the reference village (p < 0.001). Rice was the main staple food with individuals consuming 461 ± 162. g/d, followed by water spinach (103 ± 51. kg/d). Concentrations of Cd in the studied foodstuffs were elevated in the metal recycling village. Values of HQ exceeded unity for 87% of adult participants of the metal recycling community (39% had a HQ > 3), while 20% of adult participants from the reference village had an HQ > 1. We found an elevated health risk from dietary exposure to Cd in the metal recycling village compared to the reference community. WHO standard of 0.4. mg Cd/kg rice may not be protective where people consume large amounts of rice/have relatively low body weight. © 2011 Elsevier B.V. Source

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