74 results on '"Zhaofu Li"'
Search Results
52. A meta-analysis of fertilizer-induced soil NO and combined NO+N2O emissions
- Author
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Feng Lin, Jianwen Zou, Shuang Wu, Cheng Ji, Yaguo Jin, Yi Sun, Shuqing Li, Shuwei Liu, and Zhaofu Li
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Global and Planetary Change ,Crop residue ,Irrigation ,Ecology ,Ammonium nitrate ,chemistry.chemical_element ,04 agricultural and veterinary sciences ,010501 environmental sciences ,engineering.material ,01 natural sciences ,Nitrogen ,Tillage ,chemistry.chemical_compound ,chemistry ,Agronomy ,Soil water ,040103 agronomy & agriculture ,engineering ,0401 agriculture, forestry, and fisheries ,Environmental Chemistry ,Environmental science ,Nitrification ,Fertilizer ,0105 earth and related environmental sciences ,General Environmental Science - Abstract
Soils are among the important sources of atmospheric nitric oxide (NO) and nitrous oxide (N2O), acting as a critical role in atmospheric chemistry. Updated data derived from 114 peer-reviewed publications with 520 field measurements were synthesized using meta-analysis procedure to examine the N fertilizer-induced soil NO and the combined with N2O (NO+N2O) emissions across global soils. Besides factors identified in earlier reviews, additional factors responsible for NO fluxes were fertilizer type, soil C/N ratio, crop residue incorporation, tillage, atmospheric carbon dioxide concentration, drought and biomass burning. When averaged across all measurements, soil NO-N fluxes were estimated to be 4.06 kg ha−1 yr−1, with the greatest (9.75 kg ha−1 yr−1) in vegetable croplands and the lowest (0.11 kg ha−1 yr−1) in rice paddies. Soil NO emissions were more enhanced by synthetic N fertilizer (+38%), relative to organic (+20%) or mixed N (+18%) sources. Compared with synthetic N fertilizer alone, synthetic N fertilizer combined with nitrification inhibitors substantially reduced soil NO emissions by 81%. The global mean direct emission factors of N fertilizer for NO (EFNO) and combined NO+N2O (EFc) were estimated to be 1.16% and 2.58%, with 95% confidence intervals of 0.71–1.61% and 1.81–3.35%, respectively. Forests had the greatest EFNO (2.39%). Within the croplands, the EFNO (1.71%) and EFc (4.13%) were the greatest in vegetable cropping fields. Among different chemical N fertilizer varieties, ammonium nitrate had the greatest EFNO (2.93%) and EFc (5.97%). Some options such as organic instead of synthetic N fertilizer, decreasing N fertilizer input rate, nitrification inhibitor, and low irrigation frequency could be adopted to mitigate soil NO emissions. More field measurements over multi-years are highly needed to minimize the estimate uncertainties and mitigate soil NO emissions, particularly in forests and vegetable croplands. This article is protected by copyright. All rights reserved.
- Published
- 2016
53. Methane and Nitrous Oxide Emissions Reduced Following Conversion of Rice Paddies to Inland Crab–Fish Aquaculture in Southeast China
- Author
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Zhiqiang Hu, Shuang Wu, Shuwei Liu, Shuqing Li, Jianwen Zou, and Zhaofu Li
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China ,Geologic Sediments ,010504 meteorology & atmospheric sciences ,Brachyura ,Nitrous Oxide ,Fresh Water ,Wetland ,Aquaculture ,010501 environmental sciences ,01 natural sciences ,Methane ,Soil ,chemistry.chemical_compound ,Dissolved organic carbon ,Animals ,Environmental Chemistry ,0105 earth and related environmental sciences ,Air Pollutants ,geography ,geography.geographical_feature_category ,business.industry ,Atmospheric methane ,Chemical oxygen demand ,Fishes ,Environmental engineering ,Sediment ,Agriculture ,Oryza ,General Chemistry ,chemistry ,Wetlands ,Paddy field ,Environmental science ,Seasons ,business ,Environmental Monitoring - Abstract
Aquaculture is an important source of atmospheric methane (CH4) and nitrous oxide (N2O), while few direct flux measurements are available for their regional and global source strength estimates. A parallel field experiment was performed to measure annual CH4 and N2O fluxes from rice paddies and rice paddy-converted inland crab-fish aquaculture wetlands in southeast China. Besides N2O fluxes dependent on water/sediment mineral N and CH4 fluxes related to water chemical oxygen demand, both CH4 and N2O fluxes from aquaculture were related to water/sediment temperature, sediment dissolved organic carbon, and water dissolved oxygen concentration. Annual CH4 and N2O fluxes from inland aquaculture averaged 0.37 mg m(-2) h(-1) and 48.1 μg m(-2) h(-1), yielding 32.57 kg ha(-1) and 2.69 kg N2O-N ha(-1), respectively. The conversion of rice paddies to aquaculture significantly reduced CH4 and N2O emissions by 48% and 56%, respectively. The emission factor for N2O was estimated to be 0.66% of total N input in the feed or 1.64 g N2O-N kg(-1) aquaculture production in aquaculture. The conversion of rice paddies to inland aquaculture would benefit for reconciling greenhouse gas mitigation and agricultural income increase as far as global warming potentials and net ecosystem economic profits are of concomitant concern. Some agricultural practices such as better aeration and feeding, and fallow season dredging would help to lower CH4 and N2O emissions from inland aquaculture. More field measurements from inland aquaculture are highly needed to gain an insight into national and global accounting of CH4 and N2O emissions.
- Published
- 2015
54. Assessment of the AnnAGNPS model in simulating runoff and nutrients in a typical small watershed in the Taihu Lake basin, China
- Author
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Qing Xi, Chuan Luo, Quansuo Zhou, Zhaofu Li, Hengpeng Li, Zhengqin Xiong, and Jianjun Pan
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Pollution ,Hydrology ,Nutrient ,Watershed ,Coefficient of determination ,media_common.quotation_subject ,Environmental science ,Sediment ,STREAMS ,Drainage ,Surface runoff ,Earth-Surface Processes ,media_common - Abstract
The Annualized Agricultural Non-Point Source Pollution (AnnAGNPS) model is a distributed-parameter continuous-simulation watershed-scale model used to simulate runoff, sediment, nutrient, and pesticide loads exiting from agricultural areas through drainage streams. The aim of this study was to evaluate the performance and suitability of the AnnAGNPS model in predicting runoff and nitrogen and phosphorus loading in a typical small drinking water source watershed located in the region of Taihu Lake (China) using estimated yearly runoff data and monthly observed nutrient data. The estimated runoff data for the years 2005–2009 and 2010–2013 were used to calibrate and validate the annual runoff. The data for the monthly observed nutrients from July 2008 to September 2009 and December 2012 to December 2013 were used to calibrate and validate the monthly nutrient load. The results showed that the model provided satisfactory simulations of annual surface runoff, and for the calibration and validation, the coefficient of determination (R2) values were 0.96 and 0.97, respectively, and Nash–Sutcliffe efficiency coefficient (Ens) values were 0.96 and 0.97, respectively. The model was also capable of simulating the monthly nitrogen and phosphorus load, with the nitrogen load simulation yielding moderate calibration and validation results of R2 = 0.86 and 0.88, respectively, and Ens = 0.82 and 0.87, respectively, and the phosphorus load yielding slightly poorer calibration and validation results of R2 = 0.60 and 0.83, respectively, and Ens = 0.61 and − 3.86, respectively. The results obtained from applying the AnnAGNPS to this typical small watershed in the Taihu Lake basin demonstrate that the model has considerable potential as a research and management tool for comparative assessments and runoff and nutrient yield estimations in similar watersheds.
- Published
- 2015
55. Mapping Winter Wheat with Combinations of Temporally Aggregated Sentinel-2 and Landsat-8 Data in Shandong Province, China
- Author
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Xiaojun Liu, Wenmin Zhang, Feng Xu, Naitao Huang, Shuyu Zhang, Alexander V. Prishchepov, Jianjun Pan, Zongyao Quan, Xiaosan Jiang, and Zhaofu Li
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Multi-temporal ,010504 meteorology & atmospheric sciences ,Science ,Winter wheat ,0211 other engineering and technologies ,02 engineering and technology ,Spatial distribution ,01 natural sciences ,Satellite data ,temporal aggregation ,crop development phase ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences ,multi-temporal ,winter wheat ,Google earth engine ,Phenology ,fungi ,digestive, oral, and skin physiology ,food and beverages ,Sowing ,Reflectivity ,Random forest ,Temporal aggregation ,Crop development phase ,General Earth and Planetary Sciences ,Environmental science ,Physical geography - Abstract
Winter wheat is one of the major cereal crops in China. The spatial distribution of winter wheat planting areas is closely related to food security; however, mapping winter wheat with time-series finer spatial resolution satellite images across large areas is challenging. This paper explores the potential of combining temporally aggregated Landsat-8 OLI and Sentinel-2 MSI data available via the Google Earth Engine (GEE) platform for mapping winter wheat in Shandong Province, China. First, six phenological median composites of Landsat-8 OLI and Sentinel-2 MSI reflectance measures were generated by a temporal aggregation technique according to the winter wheat phenological calendar, which covered seedling, tillering, over-wintering, reviving, jointing-heading and maturing phases, respectively. Then, Random Forest (RF) classifier was used to classify multi-temporal composites but also mono-temporal winter wheat development phases and mono-sensor data. The results showed that winter wheat could be classified with an overall accuracy of 93.4% and F1 measure (the harmonic mean of producer’s and user’s accuracy) of 0.97 with temporally aggregated Landsat-8 and Sentinel-2 data were combined. As our results also revealed, it was always good to classify multi-temporal images compared to mono-temporal imagery (the overall accuracy dropped from 93.4% to as low as 76.4%). It was also good to classify Landsat-8 OLI and Sentinel-2 MSI imagery combined instead of classifying them individually. The analysis showed among the mono-temporal winter wheat development phases that the maturing phase’s and reviving phase’s data were more important than the data for other mono-temporal winter wheat development phases. In sum, this study confirmed the importance of using temporally aggregated Landsat-8 OLI and Sentinel-2 MSI data combined and identified key winter wheat development phases for accurate winter wheat classification. These results can be useful to benefit on freely available optical satellite data (Landsat-8 OLI and Sentinel-2 MSI) and prioritize key winter wheat development phases for accurate mapping winter wheat planting areas across China and elsewhere.
- Published
- 2020
56. Differences in the responses of flow and nutrient load to isolated and coupled future climate and land use changes
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Zhaofu Li, Hengpeng Li, Jianjun Pan, Hongyu Liu, Chuan Luo, Xiaomin Chen, and Rongrong Wan
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Hydrology ,China ,Environmental Engineering ,Watershed ,Land use ,Climate Change ,Hydrological modelling ,Climate change ,Representative Concentration Pathways ,Nutrients ,General Medicine ,Models, Theoretical ,Management, Monitoring, Policy and Law ,Water resources ,Hydrology (agriculture) ,Rivers ,Water Movements ,Environmental science ,Land use, land-use change and forestry ,sense organs ,skin and connective tissue diseases ,Waste Management and Disposal - Abstract
Understanding the differences in the responses of river hydrology and water quality to climate and land use changes is particularly crucial for the development and management of water resources in the future. This study was carried out to assess the isolated and coupled effects of future climate change and land use change on the flow and nutrient load of the Xitiaoxi watershed in southeast China by applying the calibrated Hydrological Simulation Program Fortran model. Four representative concentration pathways released by the Intergovernmental Panel on Climate Change and two projected land use change scenarios were used to simulate future conditions. The results indicate that climate change would result in flow increased with an average variation of 25.2% in the future, and the increased flow would be mainly concentrated on the high flow part of the total flow duration curve. Climate change would also induce seasonal shifts to nutrient load. The effects of land use change showed that nutrient load was more sensitive than flow, made Orthophosphate load increase by 2.8%-154.7%, and flow increase by 7.2%-15.1%. The results for coupled climate and land use changes indicate that flow and nutrient load would be more affected by climate change than by land use change. Climate and land use changes may amplify or weaken each other's effects on flow and nutrient load, which suggests that both should be incorporated into hydrologic models when studying the future conditions. The results of this study can help decision-makers guide management practices that aim to minimize flow and nutrient load.
- Published
- 2020
57. The reduction effects of riparian reforestation on runoff and nutrient export based on AnnAGNPS model in a small typical watershed, China
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Chuan Luo, Quansuo Zhou, Kaixia Jiang, Haiyan Zhao, Ling Chao, Min Wu, and Zhaofu Li
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China ,Watershed ,Riparian buffer ,Nitrogen ,Health, Toxicology and Mutagenesis ,010501 environmental sciences ,Forests ,01 natural sciences ,Rivers ,Environmental Chemistry ,Riparian forest ,Nonpoint source pollution ,0105 earth and related environmental sciences ,Riparian zone ,Hydrology ,geography ,geography.geographical_feature_category ,Water Pollution ,Reforestation ,Agriculture ,Forestry ,Phosphorus ,General Medicine ,Pollution ,Environmental science ,Surface runoff ,Eutrophication ,Environmental Monitoring - Abstract
The continuous deterioration of the aquatic environment in rivers and streams is increasingly causing social and political tensions. To alleviate aquatic environmental problems, especially for the nonpoint source pollution, establishment of riparian forest buffers has been demonstrated as an effective control measure. However, few comprehensive studies of the reduction effects of riparian reforestation on the aquatic environment have been performed, particularly in identifying the suitable widths of reforestation projects. In this paper, the Annualized Agricultural Non-Point Source (AnnAGNPS) model was used to simulate the reduction effects of riparian reforestation on runoff and nutrient loads in Wucun watershed, China. The results showed that 20-m, 40-m, and 60-m widths of riparian buffer reforestation had significant effects on the yearly loads of total nitrogen (TN) and total phosphorus (TP), with reduced rates of 23.21 to 56.2% and 18.16 to 52.14%, respectively. The reduction effect on annual runoff varied from 2.8 to 5.4%. Furthermore, the reduction effect of nutrients performed best during the transition period, while the best runoff reduction was found during the dry period. These distinct reductions indicated that the implementation of riparian forest buffers was capable of reducing the risk and frequency of flooding and eutrophication, especially during the wet and transition periods. Additionally, the 20-m width of riparian buffer reforestation achieved the highest reduction efficiency for runoff, and the 40-m width was the most suitable reforested riparian buffer width for TN and TP. Therefore, 40 m may be the optimum buffer width for the implementation of riparian reforestation in the Wucun watershed. These research results provided scientific information on selecting the optimum buffer width for aquatic environmental regulators and managers as the reduction effects of different widths of riparian buffers on runoff and nutrients were different when considering buffer reforestation.
- Published
- 2018
58. Comprehensive Performance Evaluation for Hydrological and Nutrients Simulation Using the Hydrological Simulation Program–Fortran in a Mesoscale Monsoon Watershed, China
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Chuan Luo, Rongrong Wan, Hengpeng Li, Kaixia Jiang, and Zhaofu Li
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China ,HSPF ,Watershed ,Health, Toxicology and Mutagenesis ,0208 environmental biotechnology ,lcsh:Medicine ,02 engineering and technology ,010501 environmental sciences ,01 natural sciences ,Article ,Phosphates ,streamflow ,nonpoint source pollution ,Taihu Lake region ,Rivers ,Water Quality ,Streamflow ,Ammonium Compounds ,East Asian Monsoon ,Computer Simulation ,Nonpoint source pollution ,0105 earth and related environmental sciences ,Hydrology ,Nitrates ,lcsh:R ,Public Health, Environmental and Occupational Health ,Models, Theoretical ,020801 environmental engineering ,Data quality ,Environmental science ,Water quality ,Nash–Sutcliffe model efficiency coefficient ,Water Pollutants, Chemical - Abstract
The Hydrological Simulation Program–Fortran (HSPF) is a hydrological and water quality computer model that was developed by the United States Environmental Protection Agency. Comprehensive performance evaluations were carried out for hydrological and nutrient simulation using the HSPF model in the Xitiaoxi watershed in China. Streamflow simulation was calibrated from 1 January 2002 to 31 December 2007 and then validated from 1 January 2008 to 31 December 2010 using daily observed data, and nutrient simulation was calibrated and validated using monthly observed data during the period from July 2009 to July 2010. These results of model performance evaluation showed that the streamflows were well simulated over the study period. The determination coefficient (R2) was 0.87, 0.77 and 0.63, and the Nash-Sutcliffe coefficient of efficiency (Ens) was 0.82, 0.76 and 0.65 for the streamflow simulation in annual, monthly and daily time-steps, respectively. Although limited to monthly observed data, satisfactory performance was still achieved during the quantitative evaluation for nutrients. The R2 was 0.73, 0.82 and 0.92, and the Ens was 0.67, 0.74 and 0.86 for nitrate, ammonium and orthophosphate simulation, respectively. Some issues may affect the application of HSPF were also discussed, such as input data quality, parameter values, etc. Overall, the HSPF model can be successfully used to describe streamflow and nutrients transport in the mesoscale watershed located in the East Asian monsoon climate area. This study is expected to serve as a comprehensive and systematic documentation of understanding the HSPF model for wide application and avoiding possible misuses.
- Published
- 2017
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59. Evaluation of the AnnAGNPS Model for Predicting Runoff and Nutrient Export in a Typical Small Watershed in the Hilly Region of Taihu Lake
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Hengpeng Li, Chuan Luo, Xiaomin Chen, and Zhaofu Li
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Canopy ,China ,Watershed ,AnnAGNPS model ,Health, Toxicology and Mutagenesis ,lcsh:Medicine ,runoff ,engineering.material ,Article ,nitrogen ,Hydrology (agriculture) ,Nutrient ,Water Quality ,Environmental monitoring ,Water Movements ,phosphorus ,Fertilizers ,parameter sensitivity analysis ,Hydrology ,lcsh:R ,Public Health, Environmental and Occupational Health ,Agriculture ,Models, Theoretical ,Lakes ,Agronomy ,Calibration ,engineering ,Environmental science ,Water quality ,Fertilizer ,Surface runoff ,Environmental Monitoring - Abstract
The application of hydrological and water quality models is an efficient approach to better understand the processes of environmental deterioration. This study evaluated the ability of the Annualized Agricultural Non-Point Source (AnnAGNPS) model to predict runoff, total nitrogen (TN) and total phosphorus (TP) loading in a typical small watershed of a hilly region near Taihu Lake, China. Runoff was calibrated and validated at both an annual and monthly scale, and parameter sensitivity analysis was performed for TN and TP before the two water quality components were calibrated. The results showed that the model satisfactorily simulated runoff at annual and monthly scales, both during calibration and validation processes. Additionally, results of parameter sensitivity analysis showed that the parameters Fertilizer rate, Fertilizer organic, Canopy cover and Fertilizer inorganic were more sensitive to TN output. In terms of TP, the parameters Residue mass ratio, Fertilizer rate, Fertilizer inorganic and Canopy cover were the most sensitive. Based on these sensitive parameters, calibration was performed. TN loading produced satisfactory results for both the calibration and validation processes, whereas the performance of TP loading was slightly poor. The simulation results showed that AnnAGNPS has the potential to be used as a valuable tool for the planning and management of watersheds.
- Published
- 2015
60. Simulation of runoff and nutrient export from a typical small watershed in China using the Hydrological Simulation Program–Fortran
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Yan Li, Hengpeng Li, Hongyu Liu, Zhengqin Xiong, Xiaosan Jiang, Quansuo Zhou, Chuan Luo, Zhaofu Li, and Jianjun Pan
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Hydrology ,China ,HSPF ,Watershed ,Nitrogen ,Calibration (statistics) ,Drinking Water ,Health, Toxicology and Mutagenesis ,Fresh Water ,Phosphorus ,General Medicine ,Land cover ,Models, Theoretical ,Pollution ,Water Movements ,Water Pollution, Chemical ,Environmental Chemistry ,Environmental science ,Computer Simulation ,Precipitation ,Water pollution ,Surface runoff ,Water content ,Water Pollutants, Chemical ,Environmental Monitoring - Abstract
The Hydrological Simulation Program-Fortran (HSPF), which is a hydrological and water-quality computer model that was developed by the United States Environmental Protection Agency, was employed to simulate runoff and nutrient export from a typical small watershed in a hilly eastern monsoon region of China. First, a parameter sensitivity analysis was performed to assess how changes in the model parameters affect runoff and nutrient export. Next, the model was calibrated and validated using measured runoff and nutrient concentration data. The Nash-Sutcliffe efficiency (E NS ) values of the yearly runoff were 0.87 and 0.69 for the calibration and validation periods, respectively. For storms runoff events, the E NS values were 0.93 for the calibration period and 0.47 for the validation period. Antecedent precipitation and soil moisture conditions can affect the simulation accuracy of storm event flow. The E NS values for the total nitrogen (TN) export were 0.58 for the calibration period and 0.51 for the validation period. In addition, the correlation coefficients between the observed and simulated TN concentrations were 0.84 for the calibration period and 0.74 for the validation period. For phosphorus export, the E NS values were 0.89 for the calibration period and 0.88 for the validation period. In addition, the correlation coefficients between the observed and simulated orthophosphate concentrations were 0.96 and 0.94 for the calibration and validation periods, respectively. The nutrient simulation results are generally satisfactory even though the parameter-lumped HSPF model cannot represent the effects of the spatial pattern of land cover on nutrient export. The model parameters obtained in this study could serve as reference values for applying the model to similar regions. In addition, HSPF can properly describe the characteristics of water quantity and quality processes in this area. After adjustment, calibration, and validation of the parameters, the HSPF model is suitable for hydrological and water-quality simulations in watershed planning and management and for designing best management practices.
- Published
- 2014
61. Comprehensive study on parameter sensitivity for flow and nutrient modeling in the Hydrological Simulation Program Fortran model
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Chuan Luo, Zhaofu Li, Kaixia Jiang, Xiaomin Chen, Hengpeng Li, and Min Wu
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HSPF ,China ,Health, Toxicology and Mutagenesis ,0208 environmental biotechnology ,02 engineering and technology ,010501 environmental sciences ,01 natural sciences ,Phosphates ,Interflow ,Hydrology (agriculture) ,Rivers ,Evapotranspiration ,Water Quality ,Water Movements ,Environmental Chemistry ,Computer Simulation ,Sensitivity (control systems) ,Groundwater ,0105 earth and related environmental sciences ,Hydrology ,General Medicine ,Groundwater recharge ,Models, Theoretical ,Pollution ,020801 environmental engineering ,Calibration ,Environmental science ,Surface runoff - Abstract
Numerous parameters are used to construct the HSPF (Hydrological Simulation Program Fortran) model, which results in significant difficulty in calibrating the model. Parameter sensitivity analysis is an efficient method to identify important model parameters. Through this method, a model’s calibration process can be simplified on the basis of understanding the model’s structure. This study investigated the sensitivity of the flow and nutrient parameters of HSPF using the DSA (differential sensitivity analysis) method in the Xitiaoxi watershed, China. The results showed that flow was mostly affected by parameters related to groundwater and evapotranspiration, including DEEPFR (fraction of groundwater inflow to deep recharge), LZETP (lower-zone evapotranspiration parameter), and AGWRC (base groundwater recession), and most of the sensitive parameters had negative and nonlinear effects on flow. Additionally, nutrient components were commonly affected by parameters from land processes, including MON-SQOLIM (monthly values limiting storage of water quality in overland flow), MON-ACCUM (monthly values of accumulation), MON-IFLW-CONC (monthly concentration of water quality in interflow), and MON-GRND-CONC (monthly concentration of water quality in active groundwater). Besides, parameters from river systems, KATM20 (unit oxidation rate of total ammonia at 20 °C) had a negative and almost linear effect on ammonia concentration and MALGR (maximal unit algal growth rate for phytoplankton) had a negative and nonlinear effect on ammonia and orthophosphate concentrations. After calibrating these sensitive parameters, our model performed well for simulating flow and nutrient outputs, with R 2 and ENS (Nash–Sutcliffe efficiency) both greater than 0.75 for flow and greater than 0.5 for nutrient components. This study is expected to serve as a valuable complement to the documentation of the HSPF model to help users identify key parameters and provide a reference for performing sensitivity analyses on other models.
- Published
- 2017
62. Inferring land use and land cover impact on stream water quality using a Bayesian hierarchical modeling approach in the Xitiaoxi River Watershed, China
- Author
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Xiaofei Nie, Rongrong Wan, Guishan Yang, Hengpeng Li, Shanshan Cai, and Zhaofu Li
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Hydrology ,China ,Conservation of Natural Resources ,Environmental Engineering ,Watershed ,Land use ,Bayes Theorem ,General Medicine ,Land cover ,Models, Theoretical ,Management, Monitoring, Policy and Law ,Agricultural land ,Water Quality ,Environmental science ,Bayesian hierarchical modeling ,Water quality ,Water pollution ,Eutrophication ,Waste Management and Disposal - Abstract
Lake eutrophication has become a very serious environmental problem in China. If water pollution is to be controlled and ultimately eliminated, it is essential to understand how human activities affect surface water quality. A recently developed technique using the Bayesian hierarchical linear regression model revealed the effects of land use and land cover (LULC) on stream water quality at a watershed scale. Six LULC categories combined with watershed characteristics, including size, slope, and permeability were the variables that were studied. The pollutants of concern were nutrient concentrations of total nitrogen (TN) and total phosphorus (TP), common pollutants found in eutrophication. The monthly monitoring data at 41 sites in the Xitiaoxi Watershed, China during 2009–2010 were used for model demonstration. The results showed that the relationships between LULC and stream water quality are so complicated that the effects are varied over large areas. The models suggested that urban and agricultural land are important sources of TN and TP concentrations, while rural residential land is one of the major sources of TN. Certain agricultural practices (excessive fertilizer application) result in greater concentrations of nutrients in paddy fields, artificial grasslands, and artificial woodlands. This study suggests that Bayesian hierarchical modeling is a powerful tool for examining the complicated relationships between land use and water quality on different scales, and for developing land use and water management policies.
- Published
- 2014
63. Study of residual stresses in A7N01 aluminum alloy with X-ray diffraction Debye ring analysis
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Zhu Pengfei, Guoqing Gou, Minhao Zhu, Wei Gao, Zhaofu Li, C.P. Ma, and Zhongyin Zhu
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Materials science ,Alloy ,chemistry.chemical_element ,02 engineering and technology ,Welding ,engineering.material ,Ring (chemistry) ,01 natural sciences ,law.invention ,symbols.namesake ,law ,Aluminium ,Residual stress ,0103 physical sciences ,Stress corrosion cracking ,Composite material ,010306 general physics ,Debye ,Statistical and Nonlinear Physics ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Fatigue limit ,chemistry ,symbols ,engineering ,0210 nano-technology - Abstract
The welding residual stress has different effects on the mechanical properties of aluminum alloy welded joints, such as size stability, fatigue strength and stress corrosion cracking. Therefore, it is very important to evaluate the welding residual stress accurately. In this paper, the residual stress of A7N01 aluminum alloy welded joints was measured by X-ray diffraction. In contrast to the traditional method, the cos[Formula: see text] method was used in this paper, the results were compared with those obtained by the conventional [Formula: see text] method. In addition, the influence of oscillation unit on the test results of the cos[Formula: see text] method was studied.
- Published
- 2019
64. Increasing summer river discharge in southern California, USA, linked to urbanization
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Hongxing Liu, Qiusheng Wu, Benjamin Thomas, Diane E. Pataki, Zhaofu Li, and Amy Townsend-Small
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Hydrology ,Irrigation ,Geophysics ,Hydrology (agriculture) ,Discharge ,Urbanization ,General Earth and Planetary Sciences ,Environmental science ,STREAMS ,Land cover ,Groundwater recharge ,Surface runoff - Abstract
[1] Semi-arid southern California relies heavily on imported water for domestic use. A synthesis of river discharge data in this region reveals that summer (June, July, and August) river discharge in watersheds that have at least 50% urban, suburban, and/or commercial land cover has increased by 250% or more over the past half-century, without any substantial precipitation during these months. Total annual discharge in the Los Angeles River has also increased at levels up to several hundred percent. Three factors likely contribute to our observations: (1) increased groundwater recharge rates from leaking water pipelines, (2) inputs of treated wastewater into streams and rivers, and (3) increased runoff or recharge due to over-irrigation of ornamental landscaping. In the southwestern United States, water importation consumes large amounts of energy and contributes to decline of river flows in source regions. Here we show that water importation also increases river flows in urban areas.
- Published
- 2013
65. A meta-analysis of fertilizer-induced soil NO and combined NO+N
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Shuwei, Liu, Feng, Lin, Shuang, Wu, Cheng, Ji, Yi, Sun, Yaguo, Jin, Shuqing, Li, Zhaofu, Li, and Jianwen, Zou
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Crops, Agricultural ,Soil ,Nitrous Oxide ,Forests ,Fertilizers ,Nitric Oxide - Abstract
Soils are among the important sources of atmospheric nitric oxide (NO) and nitrous oxide (N
- Published
- 2016
66. Impacts on wetlands of large-scale land use changes by agricultural development: the small Sanjiang plain, China
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Hongyu Liu, Shikui Zhang, Zhaofu Li, Xianguo Lu, and Qing Yang
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Wetlands -- Protection and preservation ,Environmental issues - Abstract
An attempt is made to focus on degraded wetlands in the small Sanjiang plain in China, where waterfowls, fish and plants are found in abundance. The loss of these wetlands due to agricultural development has caused a loss of a number of habitats.
- Published
- 2004
67. Impacts on Wetlands of Large-scale Land-use Changes by Agricultural Development: The Small Sanjiang Plain, China
- Author
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Xianguo Lu, Hong-Yu Liu, Qing Yang, Shikui Zhang, and Zhaofu Li
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China ,Conservation of Natural Resources ,Floodplain ,Population Dynamics ,Geography, Planning and Development ,Biodiversity ,Wetland ,Sanjiang Plain ,Birds ,Rivers ,Water Supply ,Environmental protection ,Waterfowl ,Animals ,Environmental Chemistry ,Ecosystem ,geography ,geography.geographical_feature_category ,Ecology ,biology ,Land use ,Flooding (psychology) ,Agriculture ,General Medicine ,Plants ,biology.organism_classification ,Geographic Information Systems ,Environmental science ,Surface runoff ,Environmental Monitoring - Abstract
The Small Sanjiang Plain (SSP), was formerly the largest wetland complex in China, located in the Northeastern part of Heilongjiang Province, China. Home to vast numbers of waterfowls, fish, and plants, the SSP is globally significant for biodiversity conservation. The loss and fragmentation of wetlands as a result agricultural development over 50 years has impacted wetland communities and their biodiversity. We used GIS to inventory large-scale land-use changes from 1950 to 2000, together with other statistical data. We found that 73.6% of the wetlands were lost due to agricultural development. Consequences of these land-use changes included: i) a rapid decline in waterfowl and plant species with the loss and fragmentation of natural wetlands and wetland ecosystem degradation; ii) greater variation in wetland water levels as the result of land-use changes over the years; iii) disruption of the dynamic river-floodplain connection by construction of drainage ditches and levees; and iv) a decrease in floodplain area that caused increased flooding peak flows and runoff. Here we show how these changes affect wetland biodiversity and impact important wetland species.
- Published
- 2004
68. Engineering a sensitive visual-tracking reporter system for real-time monitoring phosphorus deficiency in tobacco
- Author
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Jun Zhang, Yiting Li, Mian Gu, Guohua Xu, Panpan Li, Hongmei Fan, Xiao Zhang, and Zhaofu Li
- Subjects
Time Factors ,Transgene ,Nicotiana tabacum ,chemistry.chemical_element ,Plant Science ,Genetically modified crops ,Biology ,Genes, Plant ,Anthocyanins ,chemistry.chemical_compound ,Computer Systems ,Gene Expression Regulation, Plant ,Genes, Reporter ,Botany ,Tobacco ,Phosphorus deficiency ,RNA, Messenger ,Promoter Regions, Genetic ,Glucuronidase ,Oryza sativa ,Phosphorus ,fungi ,food and beverages ,Oryza ,biology.organism_classification ,Plants, Genetically Modified ,Genetically modified organism ,Biosynthetic Pathways ,Plant Leaves ,Horticulture ,chemistry ,Anthocyanin ,Genetic Engineering ,Agronomy and Crop Science ,Biotechnology - Abstract
Plant phosphorus (P) diagnosis is widely used for monitoring P status and guiding P fertilizer application in field conditions. The common methods for predicting plant response to P are time- and labour-consuming chemical measurements of the extractable soil P and plant P concentrations. In this study, we successfully generated a visual reporter system in tobacco (Nicotiana tabacum L.) to monitor plant P status by expressing of a Purple gene (Pr) isolated from cauliflower (Brassica oleracea var botrytis) driven by the promoter (Pro) of OsPT6, a P-starvation-induced rice gene. The leaves of OsPT6pro::Pr (PT6pro::Pr) transgenic tobacco continuously turned into dark purple with the increase of duration and severity of P deficiency, and recovered rapidly to basal green colour upon resupply of P. The expression of several anthocyanin biosynthesis involving genes was strongly activated in the transgenic tobacco in comparison to wild type under P-deficient condition. Such additive purple colour was not detected by deficiencies of other major- and micronutrients or stresses of salt, drought and cold. There was an extremely high correlation between P concentration and anthocyanin accumulation in the transgenic tobacco leaves. Using a hyperspectral sensing technology, P concentration in the leaves of transgenic plants could be predicted by the reflectance spectra at 554 nm wavelength with approximately 0.16 as the threshold value of the P deficiency. Taken together, the colour-based visual reporter system could be specifically and readily used for monitoring the plant P status by naked eyes and accurately assessed by spectral reflectance.
- Published
- 2014
69. Comprehensive Performance Evaluation for Hydrological and Nutrients Simulation Using the Hydrological Simulation Program-Fortran in a Mesoscale Monsoon Watershed, China.
- Author
-
Zhaofu Li, Chuan Luo, Kaixia Jiang, Rongrong Wan, and Hengpeng Li
- Published
- 2017
- Full Text
- View/download PDF
70. Hyperspectral remote sensing of chlorophyll-a in the Xuanwu Lake
- Author
-
Zhaofu Li and Yan Li
- Subjects
Chlorophyll a ,chemistry.chemical_compound ,Coefficient of determination ,Spectrometer ,chemistry ,Hyperspectral imaging ,Environmental science ,Spectral bands ,Spectral data ,Reflectivity ,Spectral line ,Remote sensing - Abstract
The concentration of chlorophyll-a can reflect water quality to some extent. An approach for the determination of chlorophyll-a from field reflectance spectra was presented in the Xuanwu Lake. The reflectance spectra was measured from April to May in 2009 with FieldSpec 3 portable spectrometer, and water samples were collected directly from the lake to be analyzed in lab. Using correlations between the ground-truth data and combinations of spectral bands from the field spectral data, spectral indices including single band, band ratios, and the first-derivative models were developed which could be used to estimate chlorophyll-a. The results show that single band, band ratios and the first-derivative models have a better correlation with chlorophyll-a. But the model validation results show that coefficient of determination of the band ratios and the first-derivative models are higher (R2=0.7835 and R2=0.5913 with significance level P
- Published
- 2011
71. Methane and Nitrous Oxide Emissions Reduced Following Conversion of Rice Paddies to Inland Crab -Fish Aquaculture in Southeast China.
- Author
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Shuwei Liu, Zhiqiang Hu, Shuang Wu, Shuqing Li, Zhaofu Li, and Jianwen Zou
- Published
- 2016
- Full Text
- View/download PDF
72. Evaluation of the AnnAGNPS Model for Predicting Runoff and Nutrient Export in a Typical Small Watershed in the Hilly Region of Taihu Lake.
- Author
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Chuan Luo, Zhaofu Li, Hengpeng Li, and Xiaomin Chen
- Published
- 2015
- Full Text
- View/download PDF
73. Hyperspectral remote sensing of chlorophyll-a in the Xuanwu Lake.
- Author
-
Yan Li and Zhaofu Li
- Published
- 2011
- Full Text
- View/download PDF
74. Basic theory and technical framework of coastal wetland landscape process model
- Author
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Liu, H. -Y and Zhaofu Li
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