6 results on '"Chong-Li DI"'
Search Results
2. Nitrate sources and formation of rainwater constrained by dual isotopes in Southeast Asia: Example from Singapore
- Author
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Cong-Qiang Liu, Si-Liang Li, Fu-Jun Yue, Zongbo Shi, Cai Li, Shao-Neng He, Chong-Li Di, and Earth Observatory of Singapore
- Subjects
Water Pollutants, Radioactive ,Environmental Engineering ,Meteorological Concepts ,δ18O ,Health, Toxicology and Mutagenesis ,Rain ,0208 environmental biotechnology ,02 engineering and technology ,010501 environmental sciences ,Geology [Science] ,Oxygen Isotopes ,Atmospheric sciences ,Monsoon ,01 natural sciences ,Rainwater harvesting ,Nitrate Formation ,Atmosphere ,chemistry.chemical_compound ,Isotope fractionation ,Nitrate ,Environmental Chemistry ,Ecosystem ,0105 earth and related environmental sciences ,Singapore ,Nitrates ,Nitrogen Isotopes ,Stable isotope ratio ,Stable Isotopes ,Public Health, Environmental and Occupational Health ,General Medicine ,General Chemistry ,Pollution ,020801 environmental engineering ,chemistry ,Atmospheric chemistry ,Environmental science ,Nitrogen Oxides ,Water Pollutants, Chemical ,Environmental Monitoring - Abstract
Emission of reactive nitrogen species has a major impact on atmospheric chemistry, ecosystem and human health. The origin and formation mechanisms of wet-deposited nitrate are not well understood in Southeast Asia (SEA). In this study, we measured stable isotopes of nitrate (δ15N and δ18O) and chemical compositions of daily rainwater from May 2015 to July 2017 in Singapore. Our results showed that δ15N-NO3- and δ18O-NO3- varied seasonally with higher values during the Inter-monsoon period (April-May and October-November) than during Northeast (December-March) and Southwest monsoon (June-September). Bayesian mixing modeling, which took account of the isotope fractionation, indicated that traffic emission (47 ± 32%) and lightning (19 ± 20%) contributed the most to NO3- with increased traffic contribution (55 ± 37%) in the Northeast monsoon and lightning (24 ± 23%) during the Inter-monsoon period. Biomass burning and coal combustion, likely from transboundary transport, contributed ∼25% of nitrate in the rainwater. Monte Carlo simulation of δ18O-NO3- indicated that oxidation process by hydroxyl radical contributed 65 ± 14% of NO3-, with the rest from hydrolysis of N2O5. Wind speed had large effect on δ18O-NO3- variations in the atmosphere with more involvement of hydroxyl radical reactions when wind speed increased. Our study highlights the key role of isotopic fractionation in nitrate source apportionment, and the influence of meteorological conditions on nitrate formation processes in SEA. Ministry of Education (MOE) National Research Foundation (NRF) This work is financially supported by National Natural Science Foundation of China (Grant Nos. 41571130072 and 41861144026), National Key R&D Program of China (Grant No. 2016YFA0601002) and also the IAEA Coordinated Research Project (No. 2279/R0) as well as the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centres of Excellence initiative, which comprises Earth Observatory of Singapore contribution No.231.
- Published
- 2019
3. MULTI-SCALE MODELING OF THE RESPONSE OF RUNOFF TO CLIMATE CHANGE.
- Author
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Chong-Li DI, Xiao-Hua YANG, Xing-Hui XIA, Xiao-Juan CHEN, and Jian-Qiang LI
- Subjects
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RUNOFF , *MATHEMATICAL models of hydrodynamics , *CLIMATE change , *METEOROLOGICAL precipitation , *WAVELETS (Mathematics) , *CYCLES - Abstract
With global warming, climate change has tremendously changed the hydrological processes. To discover the non-linear trend of the natural runoff and its response to precipitation and temperature in the Yellow River Basin, the non-linear relationships among the runoff, precipitation and temperature are analyzed by the wavelet decomposition and reconstruction methods, partial correlation analysis and multiple linear regression analysis. The main findings of this study are: (1) The annual natural runoff, precipitation and temperature have the similar periods (27-year, 12-year), which indicates that the periodicity of the natural annual runoff has closely relationship with the regional climate change. (2) The annual runoff, precipitation and temperature exhibit five patterns non-linear variations at five time scales (1, 2, 4, 8, 16 years), that is to say, their non-linear trends are scale-dependent with time. (3) The annual natural runoff has a significant positive correlation with the precipitation and has a negative correlation with temperature. In addition, the runoff variation is more sensitive to change in precipitation than the change in temperature at all the five time scales. (4) Although the runoff and the climate change factors have non-linear trends at different time scales, the runoff has linear correlation with the temperature and the precipitation, especially at a large time scale. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
4. AIR TEMPERATURE AND PRECIPITATION VARIATION TRENDS OF THE LANCANG RIVER UPSTREAM FROM 1957 TO 2011.
- Author
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Ya-Nan GUO, Xiao-Hua YANG, Xiao-Juan CHEN, Ying MEI, and Chong-Li DI
- Subjects
ATMOSPHERIC temperature ,PRECIPITATION (Chemistry) ,CLIMATE change ,WATER supply - Abstract
Air temperature and precipitation variation trends of the upstream of Lancang river using the time series from 1957 to 2011 are evaluated. The Mann-Kendall method is applied to study the trend and climatic jump of the air temperature and precipitation time series. It shows that the temperature has an obvious uptrend with an increase of 0.023 °C per year. The annual precipitation of the upstream of Lancang river is 954.96 mm without any change, however, the precipitation is gradually increased from upstream to downstream. This paper is significant for understanding the climate change over the years, and it has practical significance for water resources allocation and management in the future. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
5. STUDY ON SOIL MOISTURE BY THERMAL INFRARED DATA.
- Author
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Jun HE, Xiao-Hua YANG, Shi-Feng HUANG, Chong-Li DI, and Ying MEI
- Subjects
SOIL moisture ,LAND surface temperature ,DROUGHTS ,ENVIRONMENTAL management ,NORMALIZED difference vegetation index - Abstract
Information on soil moisture is important for environment management. This study bases on the daily observation to study the normalized difference vegetation index and to classify the index data. The results indicate that: (1) the index is able to adequately reflect the changes of soil moisture content in 10 cm and 20 cm thickness of soil layer during the vegetation growth period and (2) Information on soil moisture can be used for regional drought monitoring. The method can be extended for long-term monitoring of droughts over large-scale regions. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
6. PHOSPHORUS ISOTHERMAL ADSORPTION CHARACTERISTICS OF MULCH OF BIORETENTION.
- Author
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Ying MEI, Xiao-Hua YANG, Rong JIANG, Chong-Li DI, and Xue-Jun ZHANG
- Subjects
PHOSPHORUS ,ADSORPTION (Chemistry) ,GIBBS' free energy ,NONMETALS ,ATMOSPHERIC temperature - Abstract
This study aims to identify mulch of bioretention which has high phosphorus sorption capacity. The phosphorus adsorption characteristics of five types of mulch of bioretention are studied by three isothermal adsorption experiments. Results show that the Langmuir eqution is suitable for describing absorption characteristics of five types of mulch. The positive values of Gibbs free energy for phosphorus indicate that the phosphorus biosorption by five mulches is a non- -spontaneous process, and the values of mean sorption free energy of mulch are less than 8 kJ/mol, which proves that the adsorption process can be dominated by physical forces. The vermiculite is the better mulch of bioretention based on high phosphorus removal capacity. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
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