Intensive agricultural activities in the North China Plain (NCP) lead to substantial emissions of nitrogen oxides (NOx) from soil, while the role of this source on local severe ozone pollution is unknown. Here we use a mechanistic parameterization of soil NOx emissions combined with two atmospheric chemistry models to investigate the issue. We find that the presence of soil NOx emissions in the NCP significantly reduces the sensitivity of ozone to anthropogenic emissions. The maximum ozone air quality improvements in July 2017, as can be achieved by controlling all domestic anthropogenic emissions of air pollutants, decrease by 30% due to the presence of soil NOx. This effect causes an emission control penalty such that large additional emission reductions are required to achieve ozone regulation targets. As NOx emissions from fuel combustion are being controlled, the soil emission penalty would become increasingly prominent and shall be considered in emission control strategies.
Abstract. Urban air pollution has tremendous spatial variability at scales
ranging from kilometers to meters due to unevenly distributed emission
sources, complex flow patterns, and photochemical reactions. However,
high-resolution air quality information is not available through traditional
approaches such as ground-based measurements and regional air quality models
(with typical resolution > 1 km). Here we develop a 10 m
resolution air quality model for traffic-related CO pollution based on the
Parallelized Large-Eddy Simulation Model (PALM). The model performance is
evaluated with measurements obtained from sensors deployed on a taxi
platform, which collects data with a comparable spatial resolution to our
model. The very high resolution of the model reveals a detailed geographical
dispersion pattern of air pollution in and out of the road network. The
model results (0.92 ± 0.40 mg m−3) agree well with the
measurements (0.90 ± 0.58 mg m−3, n=114 502). The model has
similar spatial patterns to those of the measurements, and the r2 value
of a linear regression between model and measurement data is 0.50 ± 0.07 during non-rush hours with middle and low wind speeds. A non-linear
relationship is found between average modeled concentrations and wind speed
with higher concentrations under calm wind speeds. The modeled
concentrations are also 20 %–30 % higher in streets that align with the wind
direction within ∼ 20∘. We find that streets with
higher buildings downwind have lower modeled concentrations at the
pedestrian level, and similar effects are found for the variability in
building heights (including gaps between buildings). The modeled
concentrations also decay fast in the first ∼ 50 m from the
nearest highway and arterial road but change slower further away. This study
demonstrates the potential of large-eddy simulation in urban air quality
modeling, which is a vigorous part of the smart city system and could inform
urban planning and air quality management.
Abstract.A series of N(4)-substituted thiosemicarbazones (TSCs) bearing pyrrole unit (1a-1e) were synthesized and fully characterized by elemental analyses, infrared spectra, 1 H nuclear magnetic resonance and single crystal X-ray diffraction. The compounds were assessed as potential chemotherapeutic agents. All newly synthesized compounds were screened for their anticancer activity against lung cancer PC-9, esophageal cancer Eca-109 and gastric cancer SGC-7901 cell lines. The results of MTT, Terminal deoxynucleotidyl transferase dUTP nick end labeling and fluorescence-activated cell sorting assays indicated that all the prepared compounds exhibited cytotoxicity against PC-9, Eca-109 and SGC-7901 cells in vitro. All the compounds significantly induced cancer cell apoptosis accompanied by increasing the Bax/Bcl-2 ratio and activation of caspase-3. The structure-activity association was discussed and the potential pre-clinical trials may be conducted. The present findings have a great potential in biomedical applications of novel N(4)-substituted TSCs.
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