Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Transgenerational effects of cyanobacterial toxins on a tropical micro-crustacean Daphnia lumholtzi across three generations
Dao, Thanh-Son ; Vo, Thi-My-Chi ; Wiegand, Claudia ; Bui, Ba-Trung ; Dinh, Khuong V. - \ 2018
Environmental Pollution 243 (2018). - ISSN 0269-7491 - p. 791 - 799.
Adaptation - Life history traits - Microcystins - Tolerance - Zooplankton

Climate change and human activities induce an increased frequency and intensity of cyanobacterial blooms which could release toxins to aquatic ecosystems. Zooplankton communities belong to the first affected organisms, but in tropical freshwater ecosystems, this issue has yet been poorly investigated. We tested two questions (i) if the tropical Daphnia lumholtzi is capable to develop tolerance to an ecologically relevant concentration of purified microcystin-LR and microcystins from cyanobacterial extract transferable to F1 and F2 generations? And (ii) would F1 and F2 generations recover if reared in toxin-free medium? To answer these questions, we conducted two full factorial mutigenerational experiments, in which D. lumholtzi was exposed to MC-LR and cyanobacterial extract at the concentration of 1 μg L−1 microcystin continuously for three generations. After each generation, each treatment was spit into two: one reared in the control (toxin free) while the other continued in the respective exposure. Fitness-related traits including survival, maturity age, body length, and fecundity of each D. lumholtzi generation were quantified. Though there were only some weak negative effects of the toxins on the first generation (F0), we found strong direct, accumulated and carried-over impacts of the toxins on life history traits of D. lumholtzi on the F1 and F2, including reductions of survival, and reproduction. The maturity age and body length showed some inconsistent patterns between generations and need further investigations. The survival, maturity age (for extract), and body length (for MC-LR) were only recovered when offspring from toxin exposed mothers were raised in clean medium for two generations. Chronic exposure to long lasting blooms, even at low density, evidently reduces survival of D. lumholtzi in tropical lakes and reservoirs with ecological consequences. Exposure to environmentally relevant concentrations of cyanobacterial toxins for 3 generations tropical Daphnia lumholtzi developed no or marginal tolerance.

Warming affects growth rates and microcystin production in tropical bloom-forming microcystis strains
Bui, Trung ; Dao, Thanh Son ; Vo, Truong Giang ; Lürling, Miquel - \ 2018
Toxins 10 (2018)3. - ISSN 2072-6651
Cell quota - Climate change - Cyanobacterial blooms - Cyanotoxins - Mekong delta - Vietnam
Warming climate is predicted to promote cyanobacterial blooms but the toxicity of cyanobacteria under global warming is less well studied. We tested the hypothesis that raising temperature may lead to increased growth rates but to decreased microcystin (MC) production in tropical Microcystis strains. To this end, six Microcystis strains were isolated from different water bodies in Southern Vietnam. They were grown in triplicate at 27◦C (low), 31◦C (medium), 35◦C (high) and 37◦C (extreme). Chlorophyll-a-, particle- and MC concentrations as well as dry-weights were determined. All strains yielded higher biomass in terms of chlorophyll-a concentration and dry-weight at 31◦C compared to 27◦C and then either stabilised, slightly increased or declined with higher temperature. Five strains easily grew at 37◦C but one could not survive at 37◦C. When temperature was increased from 27◦C to 37◦C total MC concentration decreased by 35% in strains with MC-LR as the dominant variant and by 94% in strains with MC-RR. MC quota expressed per particle, per unit chlorophyll-a and per unit dry-weight significantly declined with higher temperatures. This study shows that warming can prompt the growth of some tropical Microcystis strains but that these strains become less toxic.
Zoonotic transmission of mcr-1 colistin resistance gene from small-scale poultry farms, Vietnam
Trung, Nguyen Vinh ; Matamoros, Sébastien ; Carrique-Mas, Juan J. ; Nghia, Nguyen Huu ; Nhung, Nguyen Thi ; Chieu, Tran Thi Bich ; Mai, Ho Huynh ; Rooijen, Willemien van; Campbell, James ; Wagenaar, Jaap A. ; Hardon, Anita ; Mai, Nguyen Thi Nhu ; Hieu, Thai Quoc ; Thwaites, Guy ; Jong, Menno D. de; Schultsz, Constance ; Hoa, Ngo Thi - \ 2017
Emerging Infectious Diseases 23 (2017)3. - ISSN 1080-6040 - p. 529 - 532.
We investigated the consequences of colistin use in backyard chicken farms in Vietnam by examining the prevalence of mcr-1 in fecal samples from chickens and humans. Detection of mcr-1-carrying bacteria in chicken samples was associated with colistin use and detection in human samples with exposure to mcr-1-positive chickens.
Non-Typhoidal Salmonella Colonization in Chickens and Humans in the Mekong Delta of Vietnam
Trung, N.V. ; Carrique-Mas, J.J. ; Nghia, N.H. ; Tu, L.T.P. ; Mai, H.H. ; Tuyen, H.T. ; Campbell, J. ; Nhung, N.T. ; Nhung, H.N. ; Minh, P.V. ; Chieu, T.T.B. ; Hieu, T.Q. ; Mai, N.T.N. ; Baker, S. ; Wagenaar, J.A. ; Hoa, N.T. ; Schultsz, C. - \ 2017
Zoonoses and Public Health 64 (2017)2. - ISSN 1863-1959 - p. 94 - 99.
antimicrobial resistance - chickens - colonization - humans - Non-typhoidal Salmonella - Vietnam
Salmonellosis is a public health concern in both the developed and developing countries. Although the majority of human non-typhoidal Salmonella enterica (NTS) cases are the result of foodborne infections or person-to-person transmission, NTS infections may also be acquired by environmental and occupational exposure to animals. While a considerable number of studies have investigated the presence of NTS in farm animals and meat/carcasses, very few studies have investigated the risk of NTS colonization in humans as a result of direct animal exposure. We investigated asymptomatic NTS colonization in 204 backyard chicken farms, 204 farmers and 306 matched individuals not exposed to chicken farming, in southern Vietnam. Pooled chicken faeces, collected using boot or handheld swabs on backyard chicken farms, and rectal swabs from human participants were tested. NTS colonization prevalence was 45.6%, 4.4% and 2.6% for chicken farms, farmers and unexposed individuals, respectively. Our study observed a higher prevalence of NTS colonization among chicken farmers (4.4%) compared with age-, sex- and location- matched rural and urban individuals not exposed to chickens (2.9% and 2.0%). A total of 164 chicken NTS strains and 17 human NTS strains were isolated, and 28 serovars were identified. Salmonella Weltevreden was the predominant serovar in both chickens and humans. NTS isolates showed resistance (20–40%) against tetracycline, chloramphenicol, sulfamethoxazole-trimethoprim and ampicillin. Our study reflects the epidemiology of NTS colonization in chickens and humans in the Mekong delta of Vietnam and emphasizes the need of larger, preferably longitudinal studies to study the transmission dynamics of NTS between and within animal and human host populations.
Climate Change Adaptation Strategies for Freshwater Agriculture in the Coastal Mekong Delta : Farm-scale Opportunities and Water Management Challenges
Nhan, D.K. ; Phuong, To Lan ; Son, Nguyen Ngoc ; Ha, Vo Van ; Tin, Nguyen Hong ; Pham Dang Tri, V. ; Trung, Nguyen Hieu ; Bosma, R.H. ; Halsema, G.E. van - \ 2016
Tropicultura 34 (2016)special. - ISSN 0771-3312 - p. 120 - 120.
Climate Change - Water productivity - Rice - Aquaculture - southern vietnam
Colonization of Enteroaggregative Escherichia coli and Shiga toxin-producing Escherichia coli in chickens and humans in southern Vietnam
Trung, Nguyen Vinh ; Nhung, Hoang Ngoc ; Carrique-Mas, Juan J. ; Mai, Ho Huynh ; Tuyen, Ha Thanh ; Campbell, James ; Nhung, Nguyen Thi ; Minh, Pham Van; Wagenaar, Jaap A. ; Mai, Nguyen Thi Nhu ; Hieu, Thai Quoc ; Schultsz, Constance ; Hoa, Ngo Thi - \ 2016
BMC Microbiology 16 (2016)1. - ISSN 1471-2180
Chicken - E. coli - EAEC - Humans - STEC - Vietnam

Background: Enteroaggregative (EAEC) and Shiga-toxin producing Escherichia coli (STEC) are a major cause of diarrhea worldwide. E. coli carrying both virulence factors characteristic for EAEC and STEC and producing extended-spectrum beta-lactamase caused severe and protracted disease during an outbreak of E. coli O104:H4 in Europe in 2011. We assessed the opportunities for E. coli carrying the aggR and stx genes to emerge in 'backyard' farms in south-east Asia. Results: Faecal samples collected from 204 chicken farms; 204 farmers and 306 age- and gender-matched individuals not exposed to poultry farming were plated on MacConkey agar plates with and without antimicrobials being supplemented. Sweep samples obtained from MacConkey agar plates without supplemented antimicrobials were screened by multiplex PCR for the detection of the stx1, stx2 and aggR genes. One chicken farm sample each (0.5 %) contained the stx1 and the aggR gene. Eleven (2.4 %) human faecal samples contained the stx1 gene, 2 samples (0.4 %) contained stx2 gene, and 31 (6.8 %) contained the aggR gene. From 46 PCR-positive samples, 205 E. coli isolates were tested for the presence of stx1, stx2, aggR, wzx O104 and fliC H4 genes. None of the isolates simultaneously contained the four genetic markers associated with E. coli O104:H4 epidemic strain (aggR, stx2, wzx O104 and fliC H4 ). Of 34 EAEC, 64.7 % were resistant to 3rd-generation cephalosporins. Conclusion: These results indicate that in southern Vietnam, the human population is a more likely reservoir of aggR and stx gene carrying E. coli than the chicken population. However, conditions for transmission of isolates and/or genes between human and animal reservoirs resulting in the emergence of highly virulent E. coli strains are still favorable, given the nature of'backyard' farms in Vietnam.

Value Chain Development of Avocado in Vietnam
Wertheim-Heck, S.C.O. ; Quaedackers, P. ; Nguyen Trung Anh, ; Wijk, S. van - \ 2010
Urban Agriculture Magazine 24 (2010)september 2010. - ISSN 1571-6244 - p. 35 - 37.
Rapid economic development, urbanisation and rising income levels, in Vietnam offer potential for pro-poor development, by creating new market opportunities for producers, traders and retailers. This article describes the process of value chain development, which involves all actors in the broad chain of avocado
Application of GIS in land-use planning: a case study in the Coastal Mekong Delta of Vietnam
Trung, N.H. ; Quang Tri, Le; Mensvoort, M.E.F. van; Bregt, A.K. - \ 2007
International Journal of Geoinformatics 3 (2007)4. - ISSN 1686-6576 - p. 1 - 8.
This paper presents the applications of Geographic Information System (GIS) in three different Land Use Planning (LUP) approaches: The participatory LUP (PLUP) which strongly considers the local people perceptions for land utilizations, the guidelines for LUP by FAO enhanced with multi-criteria evaluation (FAO-MCE), and the LUP and analysis system (LUPAS) using interactive multiple-goal linear programming. GIS plays an important role in the application of these approaches. In PLUP, GIS help to integrate the acquired spatial and attribute data from farmer discussions, and to analyzes the changes not only in biophysical, land cover but also in farmers' perception on land utilizations. In FAO-MCE, GIS was used to combine biophysical and socio-economic characteristics and to perform multi-criteria evaluation. In LUPAS, an optimization model was developed. The model is linked with a GIS for data input and results presentation. The land use planners can use the model to explore different land use scenarios with different objectives and constraints, both biophysically and socio-economically
Application of GIS in land-use planning, a case study in the coastal Mekong Delta of Vietnam
Trung, N.H. ; Quang Tri, Le; Mensvoort, M.E.F. van; Bregt, A.K. - \ 2006
- 6 p.
This paper presents the applications of Geoinformatics System (GIS) in three different land-use planning (LUP) approaches. The participatory LUP (PLUP) which strongly consider the local people perceptions for land utilizations, the guidelines for LUP by FAO enhanced with multi-criteria evaluation (FAO-MCE), and the land-use planning and analysis system (LUPAS) using interactive multiple-goal linear programming. The case study was two villages in the coastal area of the Mekong Delta (MD), Vietnam. The land use of the studied area is diverse, quickly shifting and strongly contrasting. The contrast is not only in terms of resources but also in economic profitability and environmental sustainability. GIS plays an important role in the successful of these three LUP approaches. In PLUP, GIS help to integrate the acquired spatial and attribute data from farmer discussions and cross-section walks, and to analyses the changes in not only biophysical, land cover changes but also farmers¿ perception changes in land utilizations. The conflicts in resources uses, mainly between agriculture and aquaculture, were also mapped and described. In FAO-MCE, a GIS was used to combine biophysical and socio-economic characteristics for land evaluation. A multi-criteria evaluation tool was developed to support the decision maker in trade-off among different stakeholders¿ interests. In LUPAS, an optimization model was developed. The model is linked with a GIS for data input and results presentation. With the optimization model, the land use planners can explore different land use scenarios with different objectives and constraints, both biophysically and socio-economically. The results of the model are sets of land use option maps with their resources requirements, e.g. labor or capital requirements, and their outputs, e.g. productions of shrimp, rice or total area of forest. This information is very important for the decision-maker to select the most suitable land use plan for the study area
Comparing land-use planning approaches in the coastal Mekong Delta of Vietnam
Trung, N.H. ; Quang Tri, Le; Mensvoort, M.E.F. van; Bregt, A.K. - \ 2006
In: Environment and Livelihoods in Tropical Coastal Zones: Managing Agriculture - Fishery - Aquaculture Conflicts / Hoanh, C.T., Tuong, T.P., Gowing, J.W., Hardy, B., Oxon (UK) : CAB International (Comprehensive Assessment of Water Management in Agriculture 2) - ISBN 1845931076 - p. 177 - 192.
Comparing land use planning approaches in the Mekong Delta, Vietnam
Trung, N.H. - \ 2006
University. Promotor(en): Arnold Bregt, co-promotor(en): M.E.F. van Mensvoort; [No Value] Le Quang Tri. - [S.l.] : S.n. - ISBN 9085044227 - 131
landgebruiksplanning - delta's - rivieren - kustgebieden - evaluatie - methodologie - vietnam - land use planning - deltas - rivers - coastal areas - evaluation - methodology
Application of GIS and Multi-criteria evaluation for land use planning in the coastal zone of the Mekong Delta, Vietnam
Trung, N.H. ; Kempen, B. ; Quang Tri, Le; Mensvoort, M.E.F. van; Bregt, A.K. - \ 2006
In: Colloque International: Application de la télédetection, des SIG et des GPS pour la réduction des risques naturels et le développement durable, 11-14 Mars, Hanoi, Vietnam. - Hanoi, Vietnam : - p. 29 - 29.
Participatory simulation of land-use changes in the northern mountains of Vietnam: the combined use of an agent-based model, a role-playing game, and a geographic information system
Castella, J.C. ; Trung, N.H. ; Boissau, S. - \ 2005
Ecology and Society 10 (2005)1. - ISSN 1708-3087 - p. 1 - 32.
natural-resource management - cover change - negotiation
In Vietnam, the remarkable economic growth that resulted from the doi moi (renovation) reforms was based largely on the rural households that had become the new basic unit of agricultural production in the early 1990s. The technical, economic, and social changes that accompanied the decollectivization process transformed agricultural production, resource management, land use, and the institutions that defined access to resources and their distribution. Combined with the extreme biophysical, technical, and social heterogeneity encountered in the northern mountains, these rapid changes led to the extreme complexity of the agrarian dynamics that today challenges traditional diagnostic approaches. Since 1999, a participatory simulation method has been developed to disentangle the cause-and-effect relationships between the different driving forces and changes in land use observed at different scales. Several tools were combined to understand the interactions between human and natural systems, including a narrative conceptual model, an agent-based spatial computational model (ABM), a role-playing game, and a multiscale geographic information system (GIS). We synthesized into an ABM named SAMBA-GIS the knowledge generated from the above tools applied to a representative sample of research sites. The model takes explicitly into account the dynamic interactions among: (1) farmers¿ strategies, i.e., the individual decision-making process as a function of the farm¿s resource profile; (2) the institutions that define resource access and usage; and (3) changes in the biophysical and socioeconomic environment. The next step consisted of coupling the ABM with the GIS to extrapolate the application of local management rules to a whole landscape. Simulations are initialized using the layers of the GIS, e.g., land use in 1990, accessibility, soil characteristics, etc., and statistics available at the village level, e.g., population, ethnicity, livestock, etc. At each annual time step, the agrarian landscape changes according to the decisions made by agent-farmers about how to allocate resources such as labor force, capital, and land to different productive activities, e.g., crops, livestock, gathering of forest products, off-farm activities. The participatory simulations based on SAMBA-GIS helped identify villages with similar land-use change trajectories to which the same types of technical and/or institutional innovations could be applied. Scenarios of land-use changes were developed with local stakeholders to assess the potential impact of these changes on the natural resource base and on agricultural development. This adaptive approach was gradually refined through interactions between researchers and the local population.
Drainage and Sanitation in unplanned Areas of Ho Chi Minh City, Vietnam
Buuren, J.C.L. van; Tran Van Thinh, ; Nguyen Trung Viet, ; Ly Khanh Tam Thao, - \ 2005
- 27 p.
GIS for participatory land use planning in the Mekong Delta, Vietnam
Trung, N.H. ; Quang Tri, Le; Mensvoort, M.E.F. van; Bregt, A.K. - \ 2004
GIS for participatory land use planning in the Mekong Delta, Vietnam
Trung, N.H. ; Quang Tri, Le; Mensvoort, M.E.F. van; Bregt, A.K. - \ 2004
The Environmental Technology and Management BSc and MSc at Van Lang University: Experiences of the REFINE project.
Buuren, J.C.L. van; Nguyen Trung Viet, - \ 2001
In: International Conference on Industry and Environment in Vietnam, Ho Chi Minh City, Vietnam, 2001. - [S.l.] : [s.n.], 2001 - p. 8 - 8.
The role of septic tanks in future sewer systems in Vietnamese cities
Buuren, J.C.L. van; Tran Van Thinh, ; Nguyen Trung Viet, ; Tran Thi My Dieu, ; Lettinga, G. - \ 2001
In: Technical papers of International Seminar on Urban Sewerage in Vietnam, Hanoi, Vietnam, 2001. - [S.l.] : [s.n.], 2001 - p. 279 - 292.
Status of industrial development in the south key economic regions of Vietnam and environmental implications
Tran Thi My Dieu, ; Nguyen Trung Viet, - \ 2001
In: Industry and Environment in Vietnam, HoChiMinh City, 2001 / P. Khanh, J. van Buuren, A.P.J. Mol et al.. - HoChiMinh City : CENTEMA/Wageningen Universiteit, 2001 - p. 132 - 144.
Sustainable treatment of rubber latex processing wastewater : the UASB-system combined with aerobic post-treatment
Viet Nguyen Trung, - \ 1999
Agricultural University. Promotor(en): G. Lettinga. - S.l. : S.n. - ISBN 9789058081032 - 218
afvalwaterbehandeling - anaërobe behandeling - latex - waste water treatment - anaerobic treatment
<p>The main objective of this PhD-thesis is to assess the applicability of UASB-process for treating RLP wastewater and the feasibility of some adequate post-treatment processes for the effluent of the anaerobic treatment process.<p>The studies were carried out in The Netherlands during November 1990-May 1991 and May 1993-October 1993, and in South Vietnam during 1991-1995.<p>The survey was carried out in six RLP factories to determine the quality and quantity of RLP wastewater. In the RLP factory, wastewater originates particularly from two main processing steps, viz. the coagulation step (serum) and the milling, cutting step. The serum wastewater is high in COD-content, viz. up to 5,015-9,962 mg/L, and its pH-values is low with values in the range of 4.95 to 5.24. The quantity of wastewater produced in crushing and milling contributes up to 80-90% of the total amount of wastewater. The COD-content of this wastewater is lower, viz. 1,800-2,400 mg/L, and the pH is higher with values in the range 6.12-6.43. The total quantity of RLP waste amounts to 25-35 m3/ton of dry rubber. The RLP wastewater contains mainly readily biodegradable organic matter (95%), such as volatile fatty acids (acetic/formic acid), and sugars, proteins and lipids, and in addition mineral salts. Considering the presence of these compounds the RLP-wastewater in principle is quite suitable for biological treatment. The raw wastewater also contains uncoagulated rubber particles at concentration up to 350 mg/L. These particles may affect an anaerobic biological process quite adversely.<p>Based on information available concerning the start-up procedure of the up-flow anaerobic sludge bed (UASB) process, four types of potentially attractive seed sludge available in South Vietnam were selected, viz. Fresh pig manure (FPM), digested pig manure sludge (DPMS), city polluted canal sludge (CS) and septic tank sludge (STS), for assessing the specific methanogenic activity (SMA).<p>The SMA of DPMS, CS, STS and FPM amount to 0.13-0.26 g COD/g VSS.d, 0.12-0.15 g COD/g VSS.d, 0.11-0.12 g COD/g VSS.d and negligible values, respectively. The DPMS are strongly recommended to use as seed sludge for full-scale UASB-reactor start-up.<p>Using a SMA test, which is simpler and therefore more adequate for use in developing countries like Vietnam, additional experiments were conducted with the aim to assess the effect of pH, oxygen and mixing conditions. In addition also the effect of the sludge storage time was investigated. The results obtained from these experiments are useful to establish the appropriate procedure for SMA test suitable for Vietnamese conditions.<p>In order to determine the design parameters for pilot and full-scale RLP wastewater treatment plants some lab-scale continuous flow experiments were carried out. From the results obtained in these experiments it appeared that the UASB-process can be applied for RLP wastewater at an organic loading rate up to 28.5 kg COD/m3.d., providing a COD removal efficiency in the range of 79.8-87.9%. The corresponding hydraulic loading rate are up to 7.3-9.1 m3/m3.d at a HRT as low as 3.3-2.6 h. and an upflow liquid velocity up to 0.4 m/h (9.6 m/d). Granular sludge formed in the UASB-reactor after 10-21 days operation. A quite adversely effect of low pH values of the RLP wastewater (i.e. as low as pH = 4.8) was found on the UASB-reactor performance. The period of time passing before the detrimental effect of low pH on the performance of the UASB-system will manifest depends, apart from the pH of the influent and the amount of non acidified organic matter present in the feed solution, particularly on the buffer capacity of sludge bed (i.e. on the accumulated amount of alkalinity in the sludge) and the loading rate imposed to the system. The sludge can recover quite well and sometimes even in a relatively short period of time from an acidic pH-upset, i.e. the UASB-system recovered completely within 2-3 days when using feed pH values in the range of 6.0-6.2.<p>The low influent pH, i.e. 4.5-4.8, and high effluent pH-value that can be reached, viz. in the range of 8.5 to 9.4, may represent true problems in the operation of a UASB-reactor for RLP wastewater, when acid formic is used in the plant for coagulation of latex. These problems can be overcome by using effluent recirculation.<p>Water hyacinth (WH) can accommodate COD concentrations in RLP wastewater up to 2,480 mg/L, and some cases up to 2,900 mg/L and the admissible concentration for algae (ALG) anyhow is lower than 2,280 mg/L, depending significantly on the adaptation procedure applied. Organic surface loads (OL) up to 100 and 120 kg COD/ha.d can be applied for design of WH and ALG ponds respectively. At influent COD concentrations below 300 mg/L effluent COD concentrations will be achieved below 100 mg/L. In order to have oxygen in the effluent, in ALG pond low OL should be used.<p>Laboratory experimental data were used to design a pilot and full scale wastewater treatment plant in Lai Khe (Binh Duong province) and Long Thanh (Dong Nai province) Rubber Latex Processing Factory. The full-scale wastewater treatment plant in Long Thanh has been operated for 4 months, starting in August 1995.<br/>
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