Sustainability assessment of coastal ecosystems: DPSIR analysis for beaches at the Northeast Coast of Vietnam

Environment, Development and Sustainability - The Northeastern coastal zone of Vietnam possesses high biodiversity and rich ecosystems like coral reefs, seagrasses, beaches and mangroves. It also...     

Water-induced erosion potentiality and vulnerability assessment in Kangsabati river basin,eastern India

Environment, Development and Sustainability - The large-scale water-induced erosion is one of the most determining elements on land degradation in subtropical monsoon-dominated region. From this...     

Barriers and enablers to climate change adaptation in hierarchical governance systems: the case of Vietnam

Governments fulfil important roles in increasing the adaptive capacity of local communities to respond to climate change impacts, particularly in developing countries. Existing studies on how governments enable and constrain the ways in which local level communities learn and build their adaptive capacity, however, generally adopt network or market-oriented types of governance. However, the most vulnerable regions to climate change impact in the world are generally governed through hierarchical policy systems. This research aims to understand how the hierarchical policy system in Vietnam creates enables and/or constrains the policy capacity of policy actors to contribute to effective climate change adaptation. We conducted interviews (n?=?26) with key actors at multiple levels of government. Our findings show the importance of clear legal institutions, available financing for implementing policies, and the training of governmental staff, particularly at district and commune levels where the policy capacities are generally too low to deal with climate change impacts. We conclude that any efforts to support local actors (i.e. smallholder farmers) should include investments in policy capacity to ensure uptake and upscaling of adaptation actions more broadly.     

Ecologically based management of rodents in the real world: applied to a mixed agroecosystem in Vietnam.

Rodents cause significant damage to lowland irrigated rice crops in the Red River Delta of Vietnam. A four-year study was conducted in 1999-2002 to examine the effectiveness of applying rodent control practices using the principles of ecologically based pest management. Four 100-150 ha study sites adjacent to villages were selected and farmers on two treated sites were asked to follow a set of rodent management practices, while farmers on the untreated sites were asked not to change their typical practices. Farmers on the treated sites were encouraged to use trap-barrier systems (TBS's; 0.065-ha early planted crop surrounded by a plastic fence with multiple capture traps; one TBS for every 10-15 ha), to work together over large areas by destroying burrows in refuge habitats soon after planting (before the rats reestablish in the fields and before the onset of breeding), synchronizing planting and harvesting of the their rice crops, cleaning up weeds and piles of straw, and keeping bund (embankment) size small (<30 cm) to prevent burrowing. A 75% reduction in the use of rodenticides and plastic barrier fences (without traps or an early crop) was achieved on treated sites. The abundance of rodents was low after implementation of the management practices across all sites. There was no evidence for an effect of treatment on the abundance of rodents captured each month using live-capture traps, and no difference in damage between treatments or in yields obtained from the rice crops. Therefore, ecologically based rodent management was equally effective as typical practices for rodent management. Farmers on the treated sites spent considerably less money applying rodent control practices, which was reflected in the comparative increase in the partial benefit:cost of applying ecologically based rodent management from 3:1 on treated sites and untreated sites prior to the implementation of treatments to 17:1 on treated sites in the final year of the project.     

Comparison of two photochemical modeling systems in a tropical urban area

Two photochemical smog modeling systems, UAM-V/ SAIMM (the Variable-Grid UAM/Systems Applications International Mesoscale Model) and CHIMERE/ECMWF (European Center for Medium Range Weather Forecast), are applied to the same tropical domain (Bangkok Metropolitan Region) and the same episode (January 13-14, 1997) to evaluate their relative performance using the same anthropogenic emission database (emission database available at the Pollution Control Department [PCD] 1997). Ozone (O3) produced by both models meets U.S. Environment Protection Agency (EPA) suggested prediction criteria of mean normalized bias error and mean normalized gross error on January 14 but none on January 13. Both models are tested with various modified databases of precursors emissions from the PCD original database. Performance of UAM-V is the best when using the modified emission data with volatile organic compound (VOC), NOx, and CO mobile source emission reduced by 50%, 50%, and 20% from the original database. CHIMERE suggests a similar emission database except for the VOC emission, which is a reduction by 40% from the original PCD mobile source emission. Spatial and temporal variations of O3, CO, NOy (total reactive nitrogen), and Ox (NO2+O3) predicted by both model systems using the modified     

Comparative study on water-soluble inorganic ions in PM2.5 from two distinct climate regions and air quality

Recently, air quality has significantly improved in developed country, but that issue is of concern in emerging megacity in developing country.In this study, aerosols and their precursor gas were collected by NILU filter pack at two distinct urban sites during the winter and summer in Osaka, Japan and dry and rainy seasons in Ho Chi Minh City(HCMC),Vietnam.The aims are to investigate the contribution of water-soluble inorganic ions(WSIIs) to PM_(2.5), thermodynamic characterization and possible formation pathway of secondary inorganic aerosol(SIA).The PM_(2.5) concentration in Osaka(15.8 μg/m~3) is lower than that in HCMC(23.0 μg/m~3), but the concentration of WSIIs in Osaka(9.0 μg/m~3) is two times higher than that in HCMC(4.1 μg/m~3).Moreover, SIA including NH_4~+, NO_3~-and SO_4~(2-)are major components in WSIIs accounting for 90% and 76%(in molar) in Osaka and HCMC,respectively.Thermodynamic models were used to understand the thermodynamic characterization of urban aerosols.Overall, statistical analysis results indicate that very good agreement(R~2 0.8) was found for all species, except for nitrate aerosol in HCMC.We found that when the crustal species present at high amount, those compositions should be included in model calculation(i.e.in the HCMC situation).Finally, we analyzed the characteristics of NH_4~+– NO_3~-– SO_4~(2-)system.A possible pathway to produce fine nitrate aerosol in Osaka is via the homogeneous reaction between NH_3 and HNO_3, while nonvolatile nitrate aerosols can be formed by the heterogeneous reactions in HCMC.     

Do Scaphoideus titanus (Hemiptera: Cicadellidae) nymphs use vibrational communication?

Small Auchenorrhyncha use substrate-borne vibrations to communicate. Although this behaviour is well known in adult leafhoppers, so far no studies have been published on nymphs. Here we checked the occurrence of vibrational communication in Scaphoideus titanus (Hemiptera: Cicadellidae) nymphs as a possible explanation of their aggregative distributions on host plants. We studied possible vibratory emissions of isolated and grouped nymphs, as well as their behavioural responses to vibration stimuli that simulated presence of conspecifics, to disturbance noise, white noise and predator spiders. None of our synthetic stimuli or pre-recorded substrate vibrations from nymphs elicited specific vibration responses and only those due to grooming or mechanical contacts of the insect with the leaf were recorded. Thus, S. titanus nymphs showed to not use species-specific vibrations neither for intra- nor interspecific communication and also did not produce alarm vibrations when facing potential predators. We conclude that their aggregative behaviour is independent from a vibrational communication.     

草酸促进双酚A在黏土矿物悬浮液中光降解研究

选择两种常见的天然黏土矿物高岭石和蒙脱石,研究了有机污染物双酚A(BPA)在其表面的吸附及草酸对黏土矿物悬浮液中BPA光降解的影响.结果表明,BPA在两种黏土矿物表面的吸附量较小,吸附符合Langmuir等温式.在250W金属卤化物灯(λ≥360nm)照射下,草酸可显著促进BPA在高岭石和蒙脱石悬浮液中的光降解,降解动力学符合Langmuir-Hinshelwood方程. 降解速率受pH值的影响较大,pH=4.0时速度最快,光降解速率同时受草酸浓度的影响.最后,通过分析矿物中铁的化学环境及反应过程中铁浓度变化,分析了草酸促进BPA在黏土矿物悬浮液中光降解的可能机制.