The main objective of this paper is to study the impact of the Ambient Air Quality Standard (2012) on the green innovation of Chinese firms in polluting industries. The analysis features "leverage ...effect" of Porter Hypothesis imposed by environmental regulations and exploits exogenous variations caused by the promulgation of the new policy. Based on the exogenous variations, this paper uses the time varying PSM-DID method. The findings of this study suggest that the implementation of the new policy improves firms' green innovation. Increments in R&D investment and environmental protection investment are channels through which the new standard positively affects firms' green innovation. The cross-sectional heterogeneity analysis exhibits that the effect of this environmental regulation is stronger for firms with bigger size and lower financial constraints. The contribution and significance of this study are as follows: our study enriches understanding of the impact of environmental regulation on firms' green innovation by empirically confirming the influencing channels of the impact of environmental regulations on green innovation. In addition, this paper contributes to the firms' green innovation literature by empirically validating the role of corporate characteristics in moderating the effect of environmental regulations.
Thin-film lithium niobate (LN) photonic integrated circuits (PICs) could enable ultrahigh performance in electro-optic and nonlinear optical devices. To date, realizations have been limited to ...chip-scale proof-of-concepts. Here we demonstrate monolithic LN PICs fabricated on 4- and 6-inch wafers with deep ultraviolet lithography and show smooth and uniform etching, achieving 0.27 dB/cm optical propagation loss on wafer-scale. Our results show that LN PICs are fundamentally scalable and can be highly cost-effective.
China has been experiencing fine particle (i.e., aerodynamic diameters ≤ 2.5 μm; PM2.5) pollution and acid rain in recent decades, which exert adverse impacts on human health and the ecosystem. ...Recently, ammonia (i.e., NH₃) emission reduction has been proposed as a strategic option to mitigate haze pollution. However, atmospheric NH₃ is also closely bound to nitrogen deposition and acid rain, and comprehensive impacts of NH₃ emission control are still poorly understood in China. In this study, by integrating a chemical transport model with a high-resolution NH₃ emission inventory, we find that NH₃ emission abatement can mitigate PM2.5 pollution and nitrogen deposition but would worsen acid rain in China. Quantitatively, a 50% reduction in NH₃ emissions achievable by improving agricultural management, along with a targeted emission reduction (15%) for sulfur dioxide and nitrogen oxides, can alleviate PM2.5 pollution by 11−17% primarily by suppressing ammonium nitrate formation. Meanwhile, nitrogen deposition is estimated to decrease by 34%, with the area exceeding the critical load shrinking from 17% to 9% of China’s terrestrial land. Nevertheless, this NH₃ reduction would significantly aggravate precipitation acidification, with a decrease of as much as 1.0 unit in rainfall pH and a corresponding substantial increase in areas with heavy acid rain. An economic evaluation demonstrates that the worsened acid rain would partly offset the total economic benefit from improved air quality and less nitrogen deposition. After considering the costs of abatement options, we propose a region-specific strategy for multipollutant controls that will benefit human and ecosystem health.
Particle phase state plays a key role in gas-particle partitioning, heterogeneous and multiphase reactions, and secondary aerosol formation. In this work, the rebound fraction and chemical ...composition of submicron particles were simultaneously measured to investigate the particle phase state and its link to chemical composition in a subtropical coastal urban city (Shenzhen, China). Submicron particles were found to be in the liquid state for most of the measurement period in spring. During the sampling time, both high relative humidity (RH, ranged from 40% to 93%) and inorganic mass fraction in particles (62.6 ± 12.4% of dry particles, on average) resulted in abundant aerosol liquid water (43 ± 6% in the wet PM1, on average), which may liquefy the particles. Considering the high frequency of ambient RH > 60% and large inorganic mass fraction in aerosol particles, we deduced that particles were in the liquid state throughout the year in coastal urban areas, where this study was performed. The liquid phase particles may accelerate the mass transfer of reactive trace gases and multiphase reactions, thereby enhanced secondary aerosol formation, further resulting in a rapid growth in aerosol mass. Our work suggested that in regions heavily impacted by SO2 and NO x emissions, especially in developing countries, the presence of inorganics could significantly impact the phase state of ambient aerosol particles, and thus the mixing state of inorganic and organic matter should be taken into account for the investigation of the aerosol phase state in urban environments.
The high-performance electrode materials with great rate capability and long cycling life are partly attributed to the microstructure and morphology of the as-prepared electrode materials for ...lithium-ion batteries (LIBs). Here, we report a facile and efficient synthetic method utilizing quantitative filter papers with negligible impurity residues in the calcining process as a sacrificial template to prepare porous Co
3
O
4
nanosheet employed as anode for LIBs. In consequence, it presents extraordinary cycling performance, e.g., superior initial specific capacity of 1326mAh g
−1
and a high reversible specific capacity of 1000 mAh g
−1
after 50 cycles at a current density of 100 mAg
−1
. The excellent electrochemical performance is ascribed to the typical porous sheet-like structure facilitating Li-ion diffusion and electron transport and alleviating considerable volume expansion in the process of lithiation/delithiation. Herein, the low-cost and eco-friendly synthetic method of porous Co
3
O
4
nanosheet could provide some enlightenment in practical application for LIBs.
Graphic abstract
The molecular composition of humic-like substances (HULIS) in different aerosol samples was analyzed using an ultrahigh-resolution mass spectrometer to investigate the influence of biomass burning on ...ambient aerosol composition. HULIS in background aerosols were characterized with numerous molecular formulas similar to biogenic secondary organic aerosols. The abundance of nitrogen-containing organic compounds (NOC), including nitrogen-containing bases (N-bases) and nitroaromatics, increased dramatically in ambient aerosols affected by crop residue burning in the farm field. The molecular distribution of N-bases in these samples exhibited similar patterns to those observed in smoke particles freshly emitted from lab-controlled burning of straw residues but were significantly different with those observed from wood burning. Signal intensity of the major N-bases correlated well with the atmospheric concentrations of potassium and levoglucosan. These N-bases can serve as molecular markers distinguishing HULIS from crop residue burning with from wood burning. More nitroaromatics were detected in ambient aerosols affected by straw burning than in fresh smoke aerosols, indicating that many of them are formed in secondary oxidation processes as smoke plumes evolve in the atmosphere. This study highlights the significant contribution of crop residue burning to atmospheric NOC. Further study is warranted to evaluate the roles of NOC on climate and human health.
To elucidate the influence of long-range transported biomass burning organic aerosols (BBOA) on the Tibetan Plateau, the molecular compositions and light absorption of HUmic-Like Substances (HULIS), ...major fractions of brown carbon, were characterized during the premonsoon season. Under the significant influence of biomass burning, HULIS concentrations increased to as high as 26 times of the background levels, accounting for 54% of water-soluble organic carbon (WSOC) and 50% of organic carbon (OC). The light absorption of HULIS also enhanced up to 42 times of the background levels, contributing 61% of the WSOC absorption and 50% of OC absorption. Meanwhile, elevated nitrogen-containing compounds (NOCs) among HULIS were observed. The NOCs from fresh and aged BBOA were unambiguously identified on the molecular level, through comparing with the molecular compositions of NOCs from lab-controlled and field burning experiments. N-Heterocyclic bases represent major fractions in the reduced nitrogen compounds from fresh BBOA, and nitroaromatic compounds are important groups among the oxidized nitrogen compounds from aged BBOA. The nitrogen-containing compounds, including nitroaromatics and N-heterocyclic compounds, were also important chromophores, which contributed to the enhanced light absorption of extracted HULIS during biomass burning-influenced periods.
PM2.5 is the key pollutant in atmospheric pollution in China. With new national air quality standards taking effect, PM2.5 has become a major issue for future pollution control. To effectively ...prevent and control PM2.5, its emission sources must be precisely and thoroughly understood. However, there are few publications reporting comprehensive and systematic results of PM2.5 source apportionment in the country. Based on PM2.5 sampling during 2009 in Shenzhen and follow-up investigation, positive matrix factorization（PMF） analysis has been carried out to understand the major sources and their temporal and spatial variations. The results show that in urban Shenzhen（University Town site）, annual mean PM2.5 concentration was 42.2 μg m？3, with secondary sulfate, vehicular emission, biomass burning and secondary nitrate as major sources; these contributed 30.0%, 26.9%, 9.8% and 9.3% to total PM2.5, respectively. Other sources included high chloride, heavy oil combustion, sea salt, dust and the metallurgical industry, with contributions between 2%–4%. Spatiotemporal variations of various sources show that vehicular emission was mainly a local source, whereas secondary sulfate and biomass burning were mostly regional. Secondary nitrate had both local and regional sources. Identification of secondary organic aerosol（SOA） has always been difficult in aerosol source apportionment. In this study, the PMF model and organic carbon/elemental carbon（OC/EC） ratio method were combined to estimate SOA in PM2.5. The results show that in urban Shenzhen, annual SOA mass concentration was 7.5 μg m？3, accounting for 57% of total organic matter, with precursors emitted from vehicles as the major source. This work can serve as a case study for further in-depth research on PM2.5 pollution and source apportionment in China.
An in-depth analysis of the specific evolution of air pollution in a given city can provide a better understanding of the chronic effects of air pollution on human health. In this study, we reported ...trends in ambient concentrations of particulate matter (PM) and gaseous pollutants sulfur dioxide (SO
2
), nitrogen dioxide (NO
2
), and ozone (O
3
) from 1995 to 2017 and PM
2.5
composition for the period of 2000–2017 in Guangzhou, Wuhan, Chongqing, and Lanzhou. We provided socio-economic indicators to help explain the pollution trends. SO
2
and PM (including PM
10
and PM
2.5
) concentrations showed a downward trend in recent years with the most notable reduction in SO
2
in Chongqing and PM
2.5
in Guangzhou. There was an overall flat trend for NO
2
, while O
3
showed an upward trend in recent years except in Lanzhou. The majority of PM
2.5
mass was SO
4
2−
(6.0–30 µg/m
3
) and organic carbon (6.0–38 µg/m
3
), followed by NO
3
−
(2.0–12 µg/m
3
), elemental carbon (2.1–12 µg/m
3
), NH
4
+
(1.0–10 µg/m
3
), K
+
(0.2–2.0 µg/m
3
), and Cl
−
(0.2–1.9 µg/m
3
). Except for secondary inorganic aerosols in Wuhan, annual average concentrations of all PM
2.5
constituents showed a declining trend after 2013, corresponding to the trend of PM
2.5
. The secondary sources in PM
2.5
were found to be most prominent in Wuhan, while the most abundant EC and Cl
−
in Lanzhou was attributed to the use of coal. Despite temporal and spatial variabilities across the four cities, coal combustion, traffic emissions, and secondary pollution have been the major sources of PM
2.5
pollution. These trends in ambient air pollution levels and PM
2.5
composition may help understand changes in health outcomes measured at different times within the time period of 1995–2017 in the four cities.
Biomass burning is one of the major sources of carbonaceous aerosols, which affects air quality,
the radiation budget and human health. Field straw residue burning is a widespread type of biomass
...burning in Asia, while its emissions are poorly understood compared with wood burning
emissions. In this study, lab-controlled straw (wheat and corn) burning experiments were designed
to investigate the emission factors and light absorption properties of different biomass burning
organic aerosol (BBOA) fractions, including water-soluble organic carbon (WSOC), humic-like
substances (HULIS) and water-insoluble organic carbon (WISOC). The influences of biofuel moisture
content and combustion efficiency on emissions are comprehensively discussed. The emission factors
of PM2.5, organic carbon (OC) and elemental carbon (EC) were 9.3±3.4, 4.6±1.9 and
0.21±0.07 g kg−1 for corn burning and 8.7±5.0, 3.9±2.8 and
0.22±0.05 g kg−1 for wheat burning, generally lower than wood or forest burning
emissions. Though the mass contribution of WISOC to OC (32 %–43 %) was lower than
WSOC, the light absorption contribution of WISOC (57 %–84 % at 300–400 nm)
surpassed WSOC due to the higher mass absorption efficiency (MAE) of WISOC. The results suggested
that BBOA light absorption would be largely underestimated if only the water-soluble
fractions were considered. However, the light absorption of WSOC in the near-UV range, occupying
39 %–43 % of the total extracted OC absorption at 300 nm, cannot be negligible
due to the sharper increase of absorption towards shorter wavelengths compared with WISOC. HULIS
were the major light absorption contributors to WSOC, due to the higher MAE of HULIS than other
high-polarity WSOC components. The emission levels and light absorption of BBOA were largely
influenced by the burning conditions, indicated by modified combustion efficiency (MCE) calculated
by measured CO and CO2 in this study. The emission factors of PM2.5,
OC, WSOC, HULIS and organic acids were enhanced under lower MCE conditions or during
higher moisture straw burning experiments. Light absorption coefficients of BBOA at
365 nm were also higher under lower MCE conditions, which was mainly due to the elevated
mass emission factors. Our results suggested that the influence of varied combustion efficiency on
particle emissions could surpass the differences caused by different types of biofuels. Thus, the
burning efficiency or conditions should be taken into consideration when estimating the influence
of biomass burning. In addition, we observed that the ratios of K+/OC and
Cl-/OC increased under higher MCE conditions due to the enhancement of
potassium and chlorine released under higher fire temperatures during flaming combustion. This indicates
that the potassium ion, as a commonly used biomass burning tracer, may lead to estimation uncertainty
if the burning conditions are not considered.
PDF
