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Four thymol derivatives and two phenolic compounds were isolated from the aerial parts of Eupatorium fortunei. The new structures were elucidated to be 7,8,9-trihydroxythymol (1), and 8,10-didehydro-7,9-dihydroxythymol (2) by means of MS and NMR analysis. The known compounds were identified as 8,9,10-trihydroxythymol (3), 10-acetoxy-8,9-dihydroxythymol (4), o-coumaric acid (5) and 4-(2-hydroxyethyl)benzaldehyde (6). Compound 3 showed strongest inhibitory effect on the growth of Microcystis aeruginosa in comparison with CuSO4.

This study characterized the carbon and phosphorus composition of buffalo manure, its compost and vermicompost and investigated if presence of bamboo biochar has an effect on their chemical and biological reactivity. The four substrates were characterized for chemical and biochemical composition and P forms. The biological stability of the four substrates and their mixtures were determined during an incubation experiment. Their chemical reactivity was analyzed after acid dichromate oxidation. Biological reactivity of these substrates was related to their soluble organic matter content, which decreased in the order buffalo manure > compost > vermicompost. Phosphorus was labile in all organic substrates and composting transformed organic P into plant available P. The presence of biochar led to a protection of organic matter against chemical oxidation and changed their susceptibility to biological degradation, suggesting that biochar could increase the carbon sequestration potential of compost, vermicompost and manure, when applied in mixture.

This study aimed to evaluate the decomposition of three exogenous organic amendments (buffalo manure, its compost and vermicompost), mixed with biochar or not, under tropical climate conditions. Litterbags containing pure substrates or mixtures were exposed to soil under natural rainfall conditions during one year. Most of C and N of exogenous organic matters (EOMs) and biochar were removed rapidly in the first 16 weeks of incubation. After one year, in case of applying alone, only around 30% of C of EOMs and 40% of C of biochar remained. Our data highlighted that in mixture, the presence of biochar led to about 40% higher amounts of C remaining, most probably related to aggregate formation preventing physical disintegration and/or leaching losses. Consequently, this study demonstrated the interest of mixing organic substrates with biochar for preventing C removal from soil immediately after field exposure. (C) 2016 Published by Elsevier B.V.

In order to understand the environmental varia- bles which promote the proliferation of cyanobacteria and variation in microcystin concentrations in the Nui Coc res- ervoir, Vietnam, physicochemical parameters, the occur- rence, and abundance of phytoplankton, cyanobacteria, and microcystin concentration were monitored monthly through the year 2009-2010. The relationships between these parameters were explored using principal component analysis (PCA) and Pearson correlation analysis. The phy- toplankton community was mainly dominated by the cya- nobacterium Microcystis with higher cyanobacteria abundance during summer and autumn season. PCA and Pearson correlation results showed that water temperature and phosphate concentration were the most important vari- ables accounting for cyanobacteria, Microcystis, and micro- cystin occurrence. Analysis of the toxins by high- performance liquid chromatography demonstrated the pres- ence of two microcystin variants: microcystin-LR (MC-RR) and microcystin-ddRR (MC-ddRR) with total concentra- tions of the toxins in filtered samples from surface water ranging from 0.11 to 1.52 μg MC-LR equiv L �1 . The high concentrations of microcystin in the Nui Coc reservoir high- lighted the potential risk for human health in the basin. Our study underlined the need for regular monitoring of cyano- bacteria and toxins in lakes and reservoirs, which are used for drinking water supplies, not only in Vietnam but also in tropical countries.

Several Vietnamese freshwater cyanobacteria were collected and evaluated for their effects on the transcriptional nuclear factor κB (NF-κB) which are involving in the cancer and inflammatory diseases. Five extraction conditions were tested and a solution of 2% acetic acid in methanol provided highest yield of extract from bacterial biomass. The Microcystis aeruginosa TC-1 and TC-3 strains showed strong NF-κB inhibitory activity with IC50 values of 6.1 and 5.3 μg/ml, respectively. Moreover, all tested cyanobacteria exhibited cytotoxicity on human cervical cancer HeLa cells in a dose-dependent manner. Ergosterol (1) isolated from M. aeruginosa TC-3 strains strongly inhibited NF-κB activation with IC50 values of 0.91 μg/ml.

International audience; Background: Exogenous organic matter may be valuable amendments for degraded tropical soil in Northern Vietnam. Their effect on carbon storage and composition need to be evaluated. Method: The study investigates soil from mesocosms cultivated with maize and amended with four different kinds of amendments: only mineral fertilizers (control), buffalo manure, compost or vermiconnpost as well as biochar. Results: All organic amendments showed a positive effect on soil carbon storage and significantly influenced soil organic matter quality. The presence of biochar increased lignin-derived compounds abundance as well as both plant and microbial sugar content of soil amended with vermicompost but had no effect in the case of control soil. Conclusion: Synergistic effects between plants and different organic amendments influence carbon storage and soil organic matter composition.

International audience; The Nui Coc reservoir (water surface: 25.2 km(2); catchment area: 567 km(2)), typical of medium sized reservoirs in Vietnam and in South East Asia, was built in the 1970s to stimulate social and economic development in the surrounding area. The nitrogen and phosphorus budgets were established in this typical reservoir catchment to determine the degree of human-induced alteration of nitrogen and phosphorus cycles. The results showed that both nitrogen and phosphorus inputs are higher than their outputs in the agricultural soil system, indicating the excess of fertilizer utilization in the catchment. The budget of the hydrosystem revealed that the nitrogen and phosphorus fluxes from agricultural and forest soils accounted for 50% and 51% of the total inputs to the hydrosystem, respectively. About 66% of the annual total nitrogen and 79% of the annual total phosphorus inputs to the hydrosystem were deposited/eliminated in the reservoir.

Silver nanoparticle (AgNP) has a wide range antibacterial effect and is extensively used in different aspects of medicine, food storage, household products, disinfectants, biomonitoring and environmental remediation etc. In the present study, we examined the growth inhibition effect of engineered silver nanoparticles against bloom forming cyanobacterial M. aeruginosa strain. AgNPs were synthesized by a chemical reduction method at room temperature and UV–Vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscope (TEM) showed that they presented a maximum absorption at 410 nm and size range between 10 and 18 nm. M. aeruginosa cells exposed during 10 d to AgNPs to a range of concentrations from 0 to 1 mg l−1. The changes in cell density and morphology were used to measure the responses of the M. aeruginosa to AgNPs. The control and treatment units had a significant difference in terms of cell density and growth inhibition (p < 0.05). Increasing the concentration of AgNPs, a reduction of the cell growths in all treatment was observed. The inhibition efficiency was reached 98.7% at higher concentration of AgNPs nanoparticles. The term half maximal effective concentration (EC50) based on the cell growth measured by absorbance at 680 nm (A680) was 0.0075 mg l−1. The inhibition efficiency was 98.7% at high concentration of AgNPs (1 mg l−1). Image of SEM and TEM reflected a shrunk and damaged cell wall indicating toxicity of silver nanoparticles toward M. aeruginosa.