Methane(CH_(4))is the second greenhouse gas and has a profound impact on global climate change due to its high global warming potential and *** 2022,the CH_(4)concentration was approximately 1.9 ppm,which was 264%of t...
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Methane(CH_(4))is the second greenhouse gas and has a profound impact on global climate change due to its high global warming potential and *** 2022,the CH_(4)concentration was approximately 1.9 ppm,which was 264%of the pre-industrial *** spatiotemporal distribution of CH_(4)was investigated by a portable CH_(4)detector on an unmanned aerial vehicle and electric bicycles in Shaoxing,a city situated in the Yangtze River Delta,*** vertical distribution revealed CH_(4)concentration generally decreased slowly with ***,the inversion condition and low atmospheric boundary layer height(ABLH)leaded to the enhancement of CH_(4)with *** highest CH_(4)concentration(2.2±0.1 ppm,n=1428)was observed in winter and the lowest(2.0±0.2 ppm,n=1530)in *** the daily variation,CH_(4)concentration peaked at 5:00 local time(LT)and reached its lowest level at 14:00 LT,which was attributed to the daily variation of ABLH,lowest in the early morning and highest in the *** urban areas,CH_(4)concentrations showed higher levels near restaurants,natural gas stations and sewerage well,with a maximum value of 13.1 ppm,which was caused by CH_(4)emission and natural gas leakage from these *** annual CH_(4)emission in Shaoxing were estimated to be approximately 69 ton/(km^(2)·year)by the mass balance *** with other cities in the world,the CH_(4)emission is in higher level which imply some control measures should be conducted to reduce CH_(4)emission in Shaoxing.
Improving the accuracy of anthropogenic volatile organic compounds(VOCs)emission inventory is crucial for reducing atmospheric pollution and formulating control policy of air *** this study,an anthropogenic speciated ...
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Improving the accuracy of anthropogenic volatile organic compounds(VOCs)emission inventory is crucial for reducing atmospheric pollution and formulating control policy of air *** this study,an anthropogenic speciated VOCs emission inventory was established for Central China represented by Henan province at a 3 km×3 km spatial resolution based on the emission *** 2019 VOCs emission in Henan provincewas 1003.5 Gg,while industrial process source(33.7%)was the highest emission source,Zhengzhou(17.9%)was the city with highest emission and April and August were the months with the more *** VOCs emission regions were concentrated in downtown areas and industrial *** and aromatic hydrocarbons were the main VOCs contribution *** species composition,source contribution and spatial distribution were verified and evaluated through tracer ratio method(TR),Positive Matrix Factorization Model(PMF)and remote sensing inversion(RSI).Results show that both the emission results by emission inventory(EI)(15.7 Gg)and by TRmethod(13.6 Gg)and source contribution by EI and PMF are *** spatial distribution of HCHO primary emission based on RSI is basically consistent with that of HCHO emission based on EI with a R-value of *** verification results show that the VOCs emission inventory and speciated emission inventory established in this study are relatively reliable.
HONO is a critical precursor of•OH,but its sources are controversial due to its complex formation *** study conducted comprehensive observations in Zhengzhou from April 26 to May 11,*** NO_(x)concentrations were obser...
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HONO is a critical precursor of•OH,but its sources are controversial due to its complex formation *** study conducted comprehensive observations in Zhengzhou from April 26 to May 11,*** NO_(x)concentrations were observed during the Covid epidemic period(EP)(10.4±3.0 ppb),compared to the pre-epidemic period(PEP)(12.5±3.8 ppb).The mean HONO concentration during EP(0.53±0.34 ppb)was 0.09 ppb lower than that during PEP(0.62±0.53 ppb).The decrease in HONO concentration during EP came mainly at night due to the reduction in the direct emission(P_(emi))(0.03 ppb/hr),the homogeneous reaction between•OHandNO(P_(OH+NO))(0.02 ppb/hr),and the heterogeneous conversion of NO_(2)on the ground(0.01 ppb/hr).Notably,there was no significant change in daytime HONO *** daytime HONO budget indicated that the primary HONO sources during PEP were the nitrate photolysis(P_(nitrate)),followed by the P_(OH+NO),Pemi,the photo-enhanced reaction of NO_(2)on the ground(P_(ground+hv))and aerosol surface(Paerosol+hv).The primary HONO sources were Pnitrate,POH+NO,P_(emi),and_(Paerosol+hv)during EP,*** missing source has a high correlation with solar radiation,there might be other photo-related HONO sources or the contributions of photosensitized reactions were *** the extremely underestimated cases,HONO production rates fromthe P_(nitrate),P_(ground+hv),and Paerosol+hv increased by 0.17,0.10,and 0.10 ppb/hr during PEP,0.23,0.13,and 0.16 ppb/hr during EP,and P_(nitrate)was still the primary source during both PEP and EP.
To identify the root causes of heavy metal contamination in soils as well as prevent and control such contamination from its sources,this study explored the accumulation patterns and ecological risks of heavy metals l...
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To identify the root causes of heavy metal contamination in soils as well as prevent and control such contamination from its sources,this study explored the accumulation patterns and ecological risks of heavy metals like Cd and Pb in solid waste in mining areas and across the water body,sediment,soil and agricultural product ecosystem surrounding the mining *** on the residual solid waste samples in lead-zinc deposits in a certain area of Guizhou province,along with samples of topsoils,irrigation water,river sediments,and crops from surrounding *** study analyzed the distributions of eight heavy metals,i.e.,Cd,As,Cr,Hg,Pb,Zn,Cu,and Ni,in the samples through field surveys and sample ***,this study assessed the contamination levels and ecological risks of heavy metals in soils,sediments,and agricultural products using methods such as the single-factor index,Nemerow composite index,and potential ecological risk *** results indicate that heavy metals in the solid waste samples all exhibited concentrations exceeding their risk screening values,with 60%greater than their risk intervention *** soils and sediments demonstrate slight and moderate comprehensive ecological risks of heavy *** single-factor potential ecological risks of heavy metals in both the soil and sediment samples decreased in the order of Hg,Cd,Pb,As,Cu,Zn,Cr,and Ni,suggesting the same sources of heavy metals in the soils and *** of the agricultural product samples exhibited over-limit concentrations of heavy metals dominated by Cd,Pb,Ni,and Cr,excluding Hg and *** agricultural product assessment using the Nemerow composite index reveals that 35%of the agricultural product samples reached the heavy metal contamination level,implying that the agricultural products from farmland around the solid waste dumps have been contaminated with heavy *** eight heavy metals in the soil,sediment,and agricultural product samples manifested hig
Generally speaking,the precursors of ozone(O_(3)),nitrogen oxides and volatile organic compounds are very low in desert areas due to the lack of anthropogenic emissions and natural emissions,and thus O_(3)concentratio...
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Generally speaking,the precursors of ozone(O_(3)),nitrogen oxides and volatile organic compounds are very low in desert areas due to the lack of anthropogenic emissions and natural emissions,and thus O_(3)concentrations are relatively ***,high summer background concentrations of about 100μg/m^(3)or 60 ppb were found in the Alxa Desert in the highland of northwest China based on continuous summer observations from 2019 to 2021,which was higher than the most of natural background areas or clean areas in world for summer O_(3)background *** high O_(3)background concentrations were related to surface features and ***-intensity anthropogenic activity areas in desert areas can cause increased O_(3)concentrations or pollution,but also generated O_(3)depleting substances such as nitrous oxide,which eventually reduced the regional O_(3)baseline *** dioxide(NO2)also had a dual effect on O_(3)generation,showing promotion at low concentrations and inhibition at high *** addition,sand-dust weather reduced O_(3)clearly,but O_(3)eventually stabilized around the background concentration values and did not vary with sand-dust particulate matter.
Scientific knowledge on the chemical compositions of fine particulate matter(PM_(2.5)) is essential for properly assessing its health and climate effects,and for decisionmakers to develop efficient mitigation strategi...
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Scientific knowledge on the chemical compositions of fine particulate matter(PM_(2.5)) is essential for properly assessing its health and climate effects,and for decisionmakers to develop efficient mitigation strategies.A high-resolution PM_(2.5) chemical composition dataset(CAQRA-aerosol)is developed in this study,which provides hourly maps of organic carbon,black carbon,ammonium,nitrate,and sulfate in China from 2013 to 2020 with a horizontal resolution of 15 *** paper describes the method,access,and validation results of this *** shows that CAQRA-aerosol has good consistency with observations and achieves higher or comparable accuracy with previous PM_(2.5) composition *** on CAQRA-aerosol,spatiotemporal changes of different PM_(2.5) compositions were investigated from a national viewpoint,which emphasizes different changes of nitrate from other *** estimated annual rate of population-weighted concentrations of nitrate is 0.23μg m^(−3)yr^(−1) from 2015 to 2020,compared with−0.19 to−1.1μg m^(−3)yr^(−1) for other *** whole dataset is freely available from the China Air Pollution Data center(https://***/10.12423/capdb_***).
In the context of global change, ensuring national food security and achieving sustainable development of agricultural production systems have become major challenges worldwide. To address these issues, regional-scale...
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In the context of global change, ensuring national food security and achieving sustainable development of agricultural production systems have become major challenges worldwide. To address these issues, regional-scale crop growth and associated process(CROP-AP) models, with their robust simulation and predictive capabilities, have emerged as important tools for studying a wide range of issues relating to agricultural production at river basin, national, and even global scales. Here, we provide a systematic review of the advances of regional-scale CROP-AP models. First, regional-scale CROP-AP models are categorized based on model characteristics: statistical models, crop growth models, hydrology-crop coupling models, and ecosystem models. The origin, development, principle, structure, and application of each model type are introduced. Then, the main functions of regional-scale CROP-AP models are critically reviewed from five aspects: crop yield prediction, crop water consumption, agricultural non-point source pollution, greenhouse gas emissions, and climate change impact and ***, the future development trends and research priorities of regional-scale CROP-AP models are explored from six key perspectives: model validation and calibration, the ability to simulate the coupling of crop physiology and human activities,enhancing model scalability, multi-model ensembles, data and code sharing, and the integration of artificial intelligence. This review aims to provide comprehensive references and insights for the further development and application of large-scale, high-precision CROP-AP models.
Based on observed meteorological elements,photolysis rates(J-values)and pollutant concentrations,an automated J-values predicting system by machine learning(J-ML)has been developed to reproduce and predict the J-value...
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Based on observed meteorological elements,photolysis rates(J-values)and pollutant concentrations,an automated J-values predicting system by machine learning(J-ML)has been developed to reproduce and predict the J-values of O^(1)D,NO_(2),HONO,H_(2)O_(2),HCHO,and NO_(3),which are the crucial values for the prediction of the atmospheric oxidation capacity(AOC)and secondary pollutant concentrations such as ozone(O_(3)),secondary organic aerosols(SOA).The J-ML can self-select the optimal“Model+Hyperparameters”without human *** evaluated results showed that the J-ML had a good performance to reproduce the J-values wheremost of the correlation(R)coefficients exceed 0.93 and the accuracy(P)values are in the range of 0.68-0.83,comparing with the J-values from observations and from the tropospheric ultraviolet and visible(TUV)radiation model in Beijing,Chengdu,Guangzhou and Shanghai,*** hourly prediction was also well performed with R from 0.78 to 0.81 for next 3-days and from 0.69 to 0.71 for next 7-days,*** with O_(3)concentrations by using J-values from the TUV model,an emission-driven observation-based model(e-OBM)by using the J-values from the J-ML showed a 4%-12%increase in R and 4%-30%decrease in ME,indicating that the J-ML could be used as an excellent supplement to traditional numerical *** feature importance analysis concluded that the key influential parameter was the surface solar downwards radiation for all J-values,and the other dominant factors for all J-values were 2-m mean temperature,O_(3),total cloud cover,boundary layer height,relative humidity and surface pressure.
VOCs(Volatile organic compounds)exert a vital role in ozone and secondary organic aerosol production,necessitating investigations into their concentration,chemical characteristics,and source apportionment for the effe...
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VOCs(Volatile organic compounds)exert a vital role in ozone and secondary organic aerosol production,necessitating investigations into their concentration,chemical characteristics,and source apportionment for the effective implementation of measures aimed at preventing and controlling atmospheric *** to October 2020,onlinemonitoringwas conducted in the main urban area of Shijiazhuang to collect data on VOCs and analyze their concentrations and ***,the PMF(positive matrix factorization)method was utilized to identify the VOCs *** indicated that the TVOCs(total VOCs)concentration was(96.7±63.4μg/m^3),with alkanes exhibiting the highest concentration of(36.1±26.4μg/m^3),followed by OVOCs(16.4±14.4μg/m^3).The key active components were alkenes and aromatics,among which xylene,propylene,toluene,propionaldehyde,acetaldehyde,ethylene,and styrene played crucial roles as reactive *** sources derived from PMF analysis encompassed vehicle emissions,solvent and coating sources,combustion sources,industrial emissions sources,as well as plant sources,the contribution of which were 37.80%,27.93%,16.57%,15.24%,and 2.46%,***,reducing vehicular exhaust emissions and encouraging neighboring industries to adopt low-volatile organic solvents and coatings should be prioritized to mitigate VOCs levels.
Nitrogen-containing organic compounds(NOCs)may potentially contribute to aqueous secondary organic aerosols,yet the different formation of NOCs in aerosol particles and cloud droplets remains *** the in-situ measureme...
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Nitrogen-containing organic compounds(NOCs)may potentially contribute to aqueous secondary organic aerosols,yet the different formation of NOCs in aerosol particles and cloud droplets remains *** the in-situ measurements performed at a mountain site(1690 m a.s.l.)in southern China,we investigated the formation of NOCs in the cloud droplets and the cloud-free particles,based on their mixing state information of NOCscontaining particles by single particle mass *** relative abundance of NOCs in the cloud-free particles was significantly higher than those in cloud residual(cloud RES)*** were highly correlated with carbonyl compounds(including glyoxalate and methylglyoxal)in the cloud-free particles,however,limited correlation was observed for cloud RES *** of their mixing state and temporal variations highlights that NOCs was mainly formed from the carbonyl compounds and ammonium in the cloud-free particles,rather than in the cloud RES *** results support that the formation of NOCs from carbonyl compounds is facilitated in concentrated solutions in wet aerosols,rather than cloud *** addition,we have identified the transport of biomass burning particles that facilitate the formation of NOCs,and that the observed NOCs is most likely contributed to the light *** findings have implications for the evaluation of NOCs formation and their contribution to light absorption.
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