Search

Based on the one-year observational data of volatile organic compounds （VOCs） in an urban area of Yuncheng in 2021， the concentration， composition， sources， and ozone-sensitive species of VOCs in four seasons were analyzed. The results showed that the average annual concentration of VOCs was （32.1 ±24.2）×10 -9 ， i.e.， at the national middle level. The seasonal concentrations of VOCs were in the order of： winter （46.3×10 -9 ）> autumn （35.5×10 -9 ）> spring （25.6×10 -9 ）> summer （21.2×10 -9 ）. Alkanes and OVOCs were the most dominant VOCs compounds， accounting for 69.0%-80.4% of TVOCs in Yuncheng. Affected by changes in source emissions， the proportion of OVOCs was higher in spring and summer （41%-43%）， whereas the proportion of alkanes was higher in autumn and winter （42%-43%）. Vehicle exhaust， LPG/NG， industrial production， and combustion sources were identified as the main sources of VOCs in Yuncheng. The largest contributors in the four seasons were vehicle exhaust （28.5% in spring）， secondary + combustion sources （29.0% in summer）， LPG/NG sources （30.4% in autumn）， and coal combustion （27.3% in winter）. The ozone formation was located in the transitional regime in summer and in the VOC-limited regime in other seasons. Ozone production was more sensitive to alkenes （isoprene， ethylene， and propene）， OVOCs （acetaldehyde and propanal）， and aromatics （xylene， toluene， and benzene）. Winter was more sensitive to ethylene， and the other seasons were more sensitive to isoprene. The primary emission sources related to these sensitive species should be reduced to achieve the goal of air quality improvement.

To deal with problems such as the difficult treatment of low-concentration fluoride-containing water and water pollution caused by excessive fluoride (F - ) discharge, aluminum and zirconium-modified biochar (AZBC) was prepared and its adsorption characteristics and adsorption mechanism for low-concentration fluoride in water were studied. The results showed that AZBC was a mesoporous biochar with uniform pore structure. It could rapidly adsorb F - from water and reach adsorption equilibrium within 20 min. When the initial ρ (F - ) was 10 mg·L -1 and the AZBC dosage was 30 g·L -1 , the removal rate was 90.7%, and the effluent concentration was lower than 1 mg·L -1 . The pH pzc of AZBC was 8.9, and the recommended pH in practical application was 3.2-8.9. The adsorption kinetics accorded with pseudo-second order kinetics, and the adsorption process accorded with the Langmuir model. The maximum adsorption capacities at 25, 35, and 45℃ were 8.91, 11.40, and 13.76 mg·g -1 , respectively. Fluoride could be desorbed by 1 mol·L -1 NaOH. The adsorption capacity of AZBC decreased by approximately 15.9% after 5 cycles. The adsorption mechanisms of AZBC were the combination of electrostatic adsorption and ion exchange.Taking actual sewage as theexperimental object, when the AZBC dosage was 10 g·L -1 , the ρ (F - ) was reduced to below 1 mg·L -1 .

Intermediate volatility organic compounds (IVOCs) are important precursors of secondary organic aerosols (SOA) but are currently not included in the conventional emissions inventories. Biomass burning represents an important source of IVOCs that could contribute to SOA formation. This study estimated the IVOC emissions from biomass burning in the Yangtze River Delta (YRD) region from 2010 to 2018 based on the fire inventory from NCAR (FINN) and the IVOCs/primary organic aerosol (POA) ratio reported in literature. During this period, the total number of fire events over the YRD region presented a declining trend, with an average of 10 4 fire events detected per year. During 2016-2018, the average number of fire events was approximately 6000 per year, which was 60% less than that prior to 2016. In terms of the monthly variation, the period from May to August was the period with the most fires observed, which was followed by a small peak in October. The results calculated based on the IVOCs/POA ratio method showed that the IVOC emissions from biomass burning exhibited large differences with different combinations of POA/OC and IVOCs/POA ratios, ranging from a maximum of 305.7×10 4 t to as small as 10.5×10 4 t. Monte Carlo simulation revealed that the uncertainties associated with the IVOCs/POA ratio method range from -99% to 68%.

Atmospheric ammonia plays an important role in the formation of secondary inorganic composition of PM 2.5 , which has attracted a high level of attention from researchers both in China and abroad. Quantifying ammonia emissions is of great scientific significance regarding research on the formation of secondary aerosol, realizing better model performance, and control of ammonia emissions. Previous studies have shown that agricultural activities are the dominant source of atmospheric ammonia, of which livestock and poultry farming contribute the most. Existing studies on estimating ammonia emissions from livestock and poultry farming activities are mostly based on emission factors and activities. However, the choice of different emission activities could lead to large differences in estimated ammonia emissions. This study makes a variety of assumptions from the selection of activity levels (volume vs. inventory) and emission coefficients (monthly vs. annual average temperature), and establishes eight scenarios from which to calculate atmospheric ammonia emissions from livestock and poultry farming in the Yangtze River Delta region in 2017. The results show that selection of different activity levels has the greatest impact on estimated ammonia emissions; estimation based on volume is higher than that based on inventory by 27.6%-34.1%. Calculation based on a more detailed monthly average temperature is higher than using average annual temperature by 3000 to 4000 tons per year. In addition, the spatial and temporal distributions of the ammonia emissions are also closely related to the choice of volume vs. inventory and the choice of monthly average temperature vs. annual average temperature. When using inventory as the emission activity, Zhoushan (Zhejiang Province) has the lowest ammonia emissions, while Huainan (Anhui Province) has the highest. In contrast, when volume is used, Lishui (Zhejiang Province) has the lowest ammonia emissions and Nanjing (Jiangsu Province) has the highest. Emissions calculations based on monthly average temperature are supposed to be more representative than those based on annual average temperature, with the highest emissions from May to September and the lowest in the winter (December, January, and February).

Intermediate volatility organic compounds (IVOCs) have a significant contribution to the formation of secondary organic aerosols (SOA) in the atmosphere, but are not included in the current emission inventory. In this study, IVOC emissions from vehicles are estimated for the Yangtze River Delta region (YRD) for 2017 based on two methods:the emission factor method and the IVOCs/POA scaling factor method. Uncertainties in the estimated IVOCs emissions and the impact on their potential formation are discussed. The results based on the emission factor method showed that the total vehicular IVOCs emission in the YRD in 2017 was 35800 tons, and that the formation potential of SOA was an estimated 695 tons. IVOCs emissions from trucks accounted for>70% of total IVOCs emissions in most cities in the YRD region. In terms of fuel type, IVOCs emissions from diesel vehicles were much higher than of those from gasoline vehicles. Results based on the IVOCs/POA scaling factor method showed that the emissions calculated by different combinations of IVOCs/POA ratios and POA/PM 2.5 ratios that could vary significantly, with a maximum of 64.2×10 4 tons and a minimum of just 5.2×10 4 tons. The resultant SOA formation potential was 1.55×10 4 tons and 1032 tons for the maximum and minimum, respectively. This study shows that the results of IVOCs emissions based on different estimation methods are associated with large uncertainties, which could directly affect the simulation results of SOA in subsequent air quality models. Therefore, it is necessary to use different inventory results in air quality models and perform model evaluation of SOA in order to obtain more accurate IVOCs emission inventories of vehicles in the YRD region.

The spatial characteristic of non-point source pollution in the Liaohe River was studied. Coupling the remote sensing data and non-point source (NPS) models, a method of assessing NPS pollution by pixel unit was developed, aiming to analyse the NPS pollution characteristic of Liaohe River basin in 2010, in turn to identify the main polluted areas and prevention measures. The work will provide technical supports for pollution prevention in Liaohe River basin. The results showed that in 2010, the total discharge of total nitrogen (TN) was 1.03 x 10(5) t, the total phosphorus (TP) was 6.8 x 10(3) t, the chemical oxygen demand (COD) was 1.31 x 10(5) t and the ammonia nitrogen (NH+4 -N) was 1. 8 x 10(4) t. The main pollution source of NPS was from agriculture. The contributions of NPS pollution to water quality were 67.4% , 76.4% , 39.4% and 21.9% for TN, TP, COD and NH+4 -N, respectively. The south of Liaohe River basin was the most serious polluted area, followed by the northeast areas. In this research, a method was build to estimate the NPS loads based on remote sensing pixel and the spatial characteristic of non-point source pollution in Liaohe River in 2010 was analysed, which will provide support for pollution prevention in Liaohe River.