Uncertainty in Regional-Scale Assessments of Non-Point Source Pollutants

2015 ◽  
pp. 131-152-3 ◽  
Author(s):  
K. Loague ◽  
Dennis L. Corwin
Keyword(s):  
Point Source ◽  
Regional Scale

scholarly journals Investigating the importance of sub-grid particle formation in point source plumes over eastern China using IAP-AACM v1.0 with a sub-grid parameterization

2021 ◽  
Vol 14 (7) ◽  
pp. 4411-4428
Author(s):  
Ying Wei ◽  
Xueshun Chen ◽  
Huansheng Chen ◽  
Yele Sun ◽  
Wenyi Yang ◽  
...  
Keyword(s):  
Point Source ◽  
Transport Model ◽  
Aerosol Particles ◽  
Eastern China ◽  
Regional Scale ◽  
Chemical Transport ◽  
Particle Formation ◽  
Point Sources ◽  
Formation Processes ◽  
New Particle Formation

Abstract. The influence of sub-grid particle formation (SGPF) in point source plumes on aerosol particles over eastern China was firstly illustrated by implementing an SGPF scheme into a global–regional nested chemical transport model with an aerosol microphysics module. The key parameter in the scheme was optimized based on the observations in eastern China. With the parameterization of SGPF, the spatial heterogeneity and diurnal variation in particle formation processes in sub-grid scale were well resolved. The SGPF scheme can significantly improve the model performance in simulating aerosol components and new particle formation processes at typical sites influenced by point sources. The comparison with observations at Beijing, Wuhan and Nanjing showed that the normal mean bias (NMB) of sulfate and ammonium could be reduced by 23 %–27 % and 12 %–14 %, respectively. When wind fields are well reproduced, the correlation of sulfate between simulation and observation can be increased by 0.13 in Nanjing. Considering the diurnal cycle of new particle formation, the SGPF scheme can greatly reduce the overestimation of particle number concentration in nucleation and Aitken mode at night caused by fixed-fraction parameterization of SGPF. On the regional scale, downwind areas of point source experienced an increase in sulfate concentration of 25 %–50 %. The results of this study indicate the significant effects of SGPF on aerosol particles over areas with the point source and the necessity of a reasonable representation of SGPF processes in chemical transport models.

scholarly journals On the conceptual complexity of non-point source management: impact of spatial variability

2020 ◽  
Vol 24 (3) ◽  
pp. 1189-1209 ◽  
Author(s):  
Christopher Vincent Henri ◽  
Thomas Harter ◽  
Efstathios Diamantopoulos
Keyword(s):  
Spatial Variability ◽  
Point Source ◽  
Travel Time ◽  
Numerical Models ◽  
Regional Scale ◽  
Capture Zone ◽  
Travel Times ◽  
Screen Length ◽  
Nps Pollution ◽  
The Impact

Abstract. Non-point source (NPS) pollution has degraded groundwater quality of unconsolidated sedimentary basins over many decades. Properly conceptualizing NPS pollution from the well scale to the regional scale leads to complex and expensive numerical models: key controlling factors of NPS pollution – recharge rate, leakage of pollutants, and soil and aquifer hydraulic properties – are spatially and, for recharge and pollutant leakage, temporally variable. This leads to high uncertainty in predicting well pollution. On the other hand, concentration levels of some key NPS contaminants (salinity, nitrate) vary within a limited range (< 2 orders of magnitude), and significant mixing occurs across the aquifer profile along the most critical compliance surface: drinking water wells with their extended vertical screen length. Given these two unique NPS contamination conditions, we here investigate the degree to which NPS travel time to wells and the NPS source area associated with an individual well can be appropriately captured, for practical applications, when spatiotemporally variable recharge, contaminant leakage rates, or hydraulic conductivity are represented through a sub-regionally homogenized parametrization. We employ a Monte Carlo-based stochastic framework to assess the impact of model homogenization on key management metrics for NPS contamination. Results indicate that travel time distributions are relatively insensitive to the spatial variability of recharge and contaminant loading, while capture zone and contaminant time series exhibit some sensitivity to source variability. In contrast, homogenization of aquifer heterogeneity significantly affects the uncertainty assessment of travel times and capture zone delineation. Surprisingly, the statistics of relevant NPS well concentrations (fast and intermediate travel times) are fairly well reproduced by a series of equivalent homogeneous aquifers, highlighting the dominant role of NPS solute mixing along well screens.

scholarly journals On the Conceptual Complexity of Non-Point Source Management: Impact of Spatial Variability

2019 ◽  
Author(s):  
Christopher Vincent Henri ◽  
Thomas Harter ◽  
Efstathios Diamantopoulos
Keyword(s):  
Point Source ◽  
Hydraulic Properties ◽  
Numerical Models ◽  
Regional Scale ◽  
Sedimentary Basins ◽  
Limited Range ◽  
Nps Pollution ◽  
Source Management ◽  
High Uncertainty

Abstract. Non-point source (NPS) pollution has degraded groundwater quality of unconsolidated sedimentary basins over many decades. Properly conceptualizing NPS pollution from the well scale to the regional scale leads to complex and expensive numerical models: Key controlling factors of NPS pollution – recharge rate, leakage of pollutants, and soil and aquifer hydraulic properties – are spatially and, for recharge and pollutant leakage, temporally variable. This leads to high uncertainty in predicting well pollution. On the other hand, concentration levels of some key NPS contaminants (salinity, nitrate) vary within a limited range (

scholarly journals Investigating the importance of sub-grid particle formation in point source plumes over eastern China using IAP-AACM with a sub-grid parameterization

2021 ◽  
Author(s):  
Ying Wei ◽  
Xueshun Chen ◽  
Huansheng Chen ◽  
Yele Sun ◽  
Wenyi Yang ◽  
...  
Keyword(s):  
Point Source ◽  
Transport Model ◽  
Aerosol Particles ◽  
Eastern China ◽  
Regional Scale ◽  
Chemical Transport ◽  
Particle Formation ◽  
Point Sources ◽  
Formation Processes ◽  
New Particle Formation

Abstract. The influence of sub-grid particle formation (SGPF) in point source plumes on aerosol particles over eastern China was firstly illustrated by implementing a SGPF scheme into a global-regional nested chemical transport model with aerosol microphysics module. The key parameter in the scheme was optimized based on the observations in eastern China. With the parameterization of SGPF, the spatial heterogeneity and diurnal variation of particle formation processes in sub-grid scale were well resolved. The SGPF scheme can significantly improve the model performance in simulating aerosol components and new particle formation processes at typical sites influenced by point sources. The comparison with observations at Beijing, Wuhan, and Nanjing showed that the normal mean bias (NMB) of sulfate and ammonium could be reduced by 23 %–27 % and 12 %–14 %, respectively. When wind fields were well reproduced, the correlation of sulfate between simulation and observation can be increased by 0.13 in Nanjing. Considering the diurnal cycle of new particle formation, the SGPF scheme can greatly reduce the overestimation of particle number concentration in nucleation and Aitken mode caused by fixed-fraction parameterization of SGPF. In the regional scale, downwind areas of point source got an increase of sulfate concentration by 25 %–50 %. The results of this study indicate the significant effects of SGPF on aerosol particles over areas with the point source and necessity of reasonable representation of SGPF processes in chemical transport models.

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