Air pollutant emissions and reduction potentials from municipal solid waste incineration in China.

China fully implemented the new emission standards in 2016 to further reduce the emissions of air pollutants from the municipal solid waste (MSW) incineration industry; however, the implementation effect of the new standards remains unknown. This study developed the first nationwide air pollutant emission inventory of MSW incineration plants in China based on the measured concentration data from China's continuous emissions monitoring systems (CEMS) network, and activity level data from the China Urban Construction Statistical Yearbook, to evaluate the effectiveness of implementing the new emission standards and estimate the future reduction potentials. Our results demonstrated that the overall standard-reaching proportions of particulate matter (PM), sulfur dioxide (SO2), nitrogen oxide (NOX), hydrogen chloride (HCl) and carbon monoxide (CO) were 98.8%, 99.3%, 99.4%, 99.4% and 97.6%, respectively, by comparing with the corresponding concentration limits of new emission standards. The total emissions of PM, SO2, NOX, HCl and CO from 412 MSW incineration plants in 2019 were 1.9, 6.2, 50.8, 4.3 and 6.6 kt yr-1, respectively, which is 33.6-75.8% lower than those in 2015, mainly due to the sharp decrease in emission factors. Pollutant emission hotspots were mainly concentrated in eastern and central and southern regions with large populations and well-developed economies. The analysis of future scenario results shows that despite the continuous increase of MSW incineration amount in the future, if the government strengthens pollutant emission standards and comprehensively implements waste sorting, total emissions and emission factors of air pollutants could be further reduced by 25.8-72.7% and 59.8-81.2%, respectively, by 2050. These findings provide helpful insights into future policymaking and technology selection for China and other countries seeking to reduce pollutant emissions from the MSW incineration industry.

Formation characteristics of long-term memory in Bactrocera dorsalis.

Studies on insects have contributed significantly to a better understanding of learning and memory, which is a necessary cognitive capability for all animals. Although the formation of memory has been studied in some model insects, more evidence is required to clarify the characteristics of memory formation, especially long-term memory (LTM), which is important for reliably storing information. Here, we explored this question by examining Bactrocera dorsalis, an agricultural pest with excellent learning abilities. Using the classical conditioning paradigm of the olfactory proboscis extension reflex (PER), we found that paired conditioning with multiple trials (>3) spaced with an intertrial interval (≥10 min) resulted in stable memory that lasted for at least 3 d. Furthermore, even a single conditioning trial was sufficient for the formation of a 2-d memory. With the injection of protein inhibitors, protein-synthesis-dependent memory was confirmed to start 4 h after training, and its dependence on translation and transcription differed. Moreover, the results revealed that the dependence of memory on protein translation exhibited a time-window effect (4-6 h). Our findings provide an integrated view of LTM in insects, suggesting common mechanisms in LTM formation that play a key role in the biological basis of memory.

Unveiling the spatial and sectoral characteristics of a high-resolution emission inventory of CO2 and air pollutants in China.

Under the target of carbon neutrality as well as stringent air quality guideline, understanding the spatial characteristics of both greenhouse gases and air pollutants emissions, in particular of their mutual sources, is crucial for assessing the feasibility of achieving their concomitant emission control, which, nevertheless, remains to be unclear yet. To this end, we construct a high-resolution (10 km × 10 km) emission inventory including both CO2 and air pollutants in China, which fosters us an opportunity to examine their spatial and sectoral characteristics. The primary sources for both CO2 and air pollutant emissions are power and industry. Among different subsectors in industry, detailed information indicates cement, iron and steel are the major subsectors for both CO2 and majority of air pollutants. Analysis of the high-resolution spatial distribution indicates that for CO2, 5 % of the grids account for 90 % of the total CO2 emissions, indicative of the existence of spatial heterogeneity. These grids are the major locations with air pollutant emissions as well, i.e., 73 % for SO2 emissions, and more than 50 % for volatile organic compounds (VOCs), CO, NOx, PM10 and PM2.5, stressing the spatial consistency between greenhouse gases and air pollutant emissions. A large portion of emissions concentrate in a relatively small number of grids further implies the possibility to achieve the mutual control of both greenhouse gas emissions and air pollutant emissions, which is useful for future policy in particular of achieving the carbon neutrality and air quality improvement.

Octopaminergic neurons function in appetitive but not aversive olfactory learning and memory in Bactrocera dorsalis.

The biogenic amine octopamine (OA, invertebrate counterpart of noradrenaline) plays critical roles in the regulation of olfactory behavior. Historically, OA has been thought to mediate appetitive but not aversive learning in honeybees, fruit flies (Drosophila), and crickets. However, this viewpoint has recently been challenged because OA activity through a ß-adrenergic-like receptor drives both appetitive and aversive learning. Here, we explored the roles of OA neurons in olfactory learning and memory retrieval in Bactrocera dorsalis. We trained flies to associate an orange odor with a sucrose reward or to associate methyl eugenol, a male lure, with N,N-diethyl-3-methyl benzoyl amide (DEET) punishment. We then treated flies with OA receptor antagonists before appetitive or aversive conditioning and a memory retention test. Injection of OA receptor antagonist mianserin or epinastine into the abdomen of flies led to impaired of appetitive learning and memory retention with a sucrose reward, while aversive learning and memory retention with DEET punishment remained intact. Our results suggest that the OA signaling participates in appetitive but not aversive learning and memory retrieval in B. dorsalis through OA receptors.

[Source Profiles and Impact of VOCs Based on Production Processes in Foundry Industries].

The characteristics of the VOCs species in foundry industries based on the production processes were analyzed through gas chromatography-mass spectrometry (GC-MS) after sampling the emissions of VOCs in 9 typical foundry enterprises using air packages and absorption tubes. The source profiles of the VOCs species in foundry industries based on production processes were established for the first time in China. In addition, the emission characteristics of VOCs and the contribution of VOCs emitted by various production processes to ozone generation were also studied. The results showed that the characteristic components of the VOCs in foundry industries were predominantly aromatic hydrocarbons, halogenated hydrocarbons, and oxygenated hydrocarbons. The average concentrations were 50.9%, 20.8%, and 12.6%, respectively. In general, aromatic hydrocarbons, such as toluene, benzene, and m/p-xylene; halogenated hydrocarbons, such as trichloroethylene and dichloromethane; oxygenated hydrocarbons, such as acetone, ethyl acetate, cyclopentanone, and some alkanes, were the primary VOCs species of the foundry industries. The emission characteristics of different production processes were related to the solvents and surface treating agents used by each process. The results also demonstrated that painting was the largest contributor of VOCs concentrations among all the production processes, followed by the modeling procedure and the silica sol and pouring processes. The OFP values for the different production processes ranged from 0.29-96.09 mg·m-3. Painting was the largest contributor to OFP, followed by the modeling procedure and the melting and pouring processes. Aromatic hydrocarbons and oxygenated hydrocarbons were the dominant contributors to OFP, and 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, toluene, and m/p-xylene were the main active components in the foundry industry, with a total contribution to the ozone generation potential of nearly 60%. It is suggested that the painting process should be prioritized regarding control measures to reduce its emissions and impact, while the waste gas from the modeling procedure and the melting and pouring processes should be collected efficiently and treated properly before being discharged to the environment.

Air pollution emissions from Chinese power plants based on the continuous emission monitoring systems network.

To meet the growing electricity demand, China's power generation sector has become an increasingly large source of air pollutants. Specific control policymaking needs an inventory reflecting the overall, heterogeneous, time-varying features of power plant emissions. Due to the lack of comprehensive real measurements, existing inventories rely on average emission factors that suffer from many assumptions and high uncertainty. This study is the first to develop an inventory of particulate matter (PM), SO2 and NOX emissions from power plants using systematic actual measurements monitored by China's continuous emission monitoring systems (CEMS) network over 96-98% of the total thermal power capacity. With nationwide, source-level, real-time CEMS-monitored data, this study directly estimates emission factors and absolute emissions, avoiding the use of indirect average emission factors, thereby reducing the level of uncertainty. This dataset provides plant-level information on absolute emissions, fuel uses, generating capacities, geographic locations, etc. The dataset facilitates power emission characterization and clean air policy-making, and the CEMS-based estimation method can be employed by other countries seeking to regulate their power emissions.

[Inventory and Distribution Characteristics of China's Thermal Power Emissions Under Ultra-Low Reconstruction].

This study updates a bottom-up high-resolution emission inventory and estimates the concentrations, emission factors, emissions, and performance values of China's power plants, based on the data from continuous emission monitoring systems and environmental statistics in 2018. The results show that the ultra-low emission policy has significant effects: the average concentrations of SO2, NOx, and PM in thermal power plants were 37.57, 56.71, and 7.41 mg ·m-3, respectively in 2018, which were 58.71%, 43.12%, and 60.79% lower than those in 2015. The average emission factors of SO2, NOx, and PM from coal-fired units in China were 0.3, 0.48, and 0.06 g ·kg-1, respectively, which were 55.2%, 36.84%, and 62.5% lower than those in 2015. The total emissions of SO2, NOx, PM, and PM2.5in thermal power plants were 721.4, 1183.8, 149.0, and 135.9 kt ·a-1, respectively, down by 41.32%, 19.29%, 48.12%, and 40.39% from 2015.

Characteristics of PCDD/Fs and metals in surface soil around an iron and steel plant in North China Plain.

In this study, the level of 18 species of metals and 17 species of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were monitored in surface soil samples around an iron and steel plant in the North China Plain. The concentration of PCDD/Fs and metals in the soil ranged from 0.16 to 4.5 ng I-TEQ/kg and 1.2 to 24,182.2 mg/kg, respectively. Furthermore, the prevailing winds were confirmed to influence the spatial distribution of PCDD/Fs and metals concentrations. The highest concentration of PCDD/Fs was located in downwind soil sample 4 (S4), which showed more than 50% of PCDFs in the total PCDD/Fs, and high levels of lower chlorinated PCDFs. Moreover, the highest Cd and Zn concentrations of 18.1 and 2647.8 mg/kg, respectively, were observed in soil collected from S4, which were significantly above the government guidelines for metals in farmland soil. Our results show that a group of metals (Mg, Al, K, Fe, Cu, Zn, Se, Cd, Sb and Pb) was well correlated with all PCDD/Fs except three (OCDD, 1,2,3,4,6,7,8-HpCDD and 1,2,3,7,8,9-HxCDD), which likely originated from iron and steel processes. Additionally, Pb, Zn, Cd and all polychlorinated dibenzofurans showed a good correlation and grouped in one cluster, suggesting anthropogenic sources from sintering process. Therefore, the metallic characteristics in soil, especially the Pb, Zn and Cd tracers, implied evidence of the accumulation of PCDD/Fs from sinter plants.