Assessing impact of surface ozone exposure on major crops production in Southern Vietnam and mitigation strategies | |
| Author | Ngo Thanh Danh |
| Call Number | AIT Diss. no.EV-17-02 |
| Subject(s) | Air--Pollution--Vietnam Air quality management--Vietnam |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. EV-17-02 |
| Abstract | An increasing trend of the surface ozone (O3) has been observed over the last two decades in many large urban areas of Asian developing countries. The current high levels of this phytotoxic pollutant may already cause adverse effects on agricultural crops. In the scenario of climate change and higher emission of its precursors in the future, higher O3may occur in Asia hence would result in more loss of crop yields in the region. This study aimed to test a hypothesis that it is possible to use suitable cropping systems to minimize O3effects in the future emission scenario. O3in the Eastern Region of Southern (ERS) of Vietnam were simulated using the WRF-CAMx model for the base year of 2010 (BY2010). The model evaluation was done using time series, scatter plots,spatial distribution as well as statistical criteria using available monitoring data in the domain and showed a moderate performance. The model was used to simulate O3in 2030 using the future emissionfollowing the RCP8.5 scenario. The simulated O3in 2010 and 2030 were used to assess the O3induced rice production loss (RPL) in the domain. Alternative cropping systemswere proposed to avoid excessive crop production loss in the future high O3scenario, considering both the sensitivity of substitute cropsfor rice and phenology of rice plant. CAMx model was run using the prepared emissioninput dataof both anthropogenic and biogenic sources in 2010 and 2030 and the 2010 WRF simulated meteorology. The initial and boundary conditions ofCAMxouter domain (Vietnam inland, resolution of 12x 12km2) for both 2010 and 2030 simulations were extracted from a previous Southeast Asia (SEA) simulation. O3in the inner domain of ERS (4 x 4km2)was simulated using the boundary conditions generated by the outer domain simulation. There are three rice crop cycles in the study domain. Simulated O3was higher in January˗February (largely overlaps the first rice crop) and September˗December (third crop), and lower in March˗June (second crop). Higher O3wassimulated in Tay Ninh (TN) province located downwind of Ho Chi Minh city (HCMC) with high emission intensity and the lowest O3was simulated for Ba Ria-Vung Tau (BR-VT) province. The rice yield loss (RYL) was assessed using the concentration-based metrics of AOT40 and M7, as well as the flux˗based metrics of POD10for each of six provinces in ERS. The highest RYL was produced by POD10followed by AOT40 and the lowest by M7. RPL in ERS due to O3exposure in 2010 were the highest for the first crop of 25,800 tonnes (~ 5.7%)of the total rice production), the second highest for the third crop of 21,500 tonnes (~ 3.8%) and the least for the second crop of up to 6,800 tonnes (~ 1.7%). The highest RPL was found to occur in TN province while the lowest RPL was in BR-VT consistent to the simulated O3levels. Due to higher simulated O3in 2030 under RCP8.5, the RPL of ERS was higher than that in 2010 with the highest RPL of 38,042 tonnes (~8.7%) for the first crop and 13,844 tonnes (~3.4%) for the second crop and 17,365 tonnes (~3.2%) for the third crop. The potential production loss of other crops in ERS, i.e. soybean and maize, was also assessed using AOT40 which showed higher loss in 2030 (41 and 4,578 tonnes, respectively) as compared to 2010 (27 tonnes and 1,063 tonnes, respectively). Based on the land-use planning of different provinces in ERS, this study recommended an alternative cropping system for the domain by substituting rice by maize in water shortage areas into the period of high O3in the third rice crop. This could bring in least economic loss due to vO3exposure in the future, i.e. 81,600 million VNĐ, as compared to the loss in 2030 using the existing copping system 145,800 million VNĐ). The loss estimated for 2010 with the current cropping system in 2010 was 101,400 million VNĐ. Thus, considering the impacts of future O3on crops would minimize the loss. Another approach was suggested that links to earlier sowing (by 15 days) to avoid the excessive exposure to O3by rice plant during the accumulation period in the third crop. A combination of both approaches may be considered in the future crop planning. Further studies of crop production loss should be based on multi-year simulated O3for future using future climate conditions. Different emission reduction scenarios as well as effects of other phytotoxic pollutants should also be considered. Relevant RYL functions should be developed for local cultivars of Vietnam using the experiment data. The alternative cropping systems could be developed for a large domain or the whole country to enhance a better land-use/crop planning process |
| Year | 2017 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. EV-17-02 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Nguyen Thi Kim Oanh |
| Examination Committee(s) | Shipin, Oleg ;Soni, Peeyush |
| Scholarship Donor(s) | People’s Committee of Ba Ria˗Vung Tau Province ;Department of Home Affairs, Vietnam |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2017 |