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The effectiveness of national policies for air pollution control has been demonstrated, but the relative effectiveness of short-term emission reduction measures in comparison with national policies has not. Here we show that short-term abatement measures during important international events substantially reduced PM2.5 concentrations, but air quality rebounded to pre-event levels after the measures ceased. Long-term adherence to strict emission reduction policies led to successful decreases of 54% in PM2.5 concentrations in Beijing, and 23% in atmospheric nitrogen deposition in China from 2012 to 2020. Incentivized by "blue skies" type campaigns, economic development and reactive nitrogen pollution are quickly decoupled, showing that a combination of inspiring but aggressive short-term measures and effective but durable long-term policies delivers sustainable air quality improvement. However, increased ammonia concentrations, transboundary pollutant flows, and the complexity to achieving reduction targets under climate change scenarios, underscore the need for the synergistic control of multiple pollutants and inter-regional action. In response to the rebound of air pollution during large events in China, the authors propose that a combination of ambitious short-term measures and enduring long-term pollution control policies is a sustainable solution for improving air quality. [ABSTRACT FROM AUTHOR]

Elevated atmospheric reactive nitrogen (Nr) emissions and the subsequent nitrogen (N) deposition have negatively impacted the global environment, particularly in China. In order to assess the long-term trends in atmospheric N deposition in the south of China, Taojiang County in Hunan Province was selected as a representative rural area for study. We analyzed interannual variation in atmospheric Nr, including gaseous ammonia (NH3), nitrogen dioxide (NO2), nitrate acid (HNO3) vapor, particulate ammonium (NH4+), and nitrate (NO3−) in air and NH4+-N and NO3−-N in precipitation from 2011 to 2020. The 10-year average atmospheric wet-plus-dry N deposition was 41.9 kg N ha−1 yr−1, which decreased by approximately 24% after 2012, indicating that NH3 and NOx emissions were effectively reduced by emission controls introduced in 2013. Wet deposition accounted for approximately 74% of the total N deposition and was significantly influenced by annual precipitation amount. Reduced N (NH3, pNH4+, and NH4+ in rainwater) was the dominant form, comprising approximately 58% of the total N deposition, while oxidized N (pNO3−, NO2, HNO3, and NO3− in rainwater) accounted for 42% of the total N deposition. Atmospheric HNO3, NO2, and NH3 concentrations and deposition declined by 30–80% over the decade, while particulate NH4+ and NO3− concentrations and deposition remained at relatively stable levels, which suggests that ongoing research and policy should focus on rural particulate pollution. Future strategies must concentrate on the integrated control of NH3 and NOx emissions to mitigate air pollution and protect human health, particularly in rural areas because current abatement efforts are primarily directed toward urban areas and the industrial sector, whereas non-point source NH3 pollution, influenced mainly by agricultural activities, dominates in rural regions. [ABSTRACT FROM AUTHOR]

Background: Blonanserin (BNS) had been undergoing post-market surveillance (PMS) since September 2018. Using the surveillance data, we did this analysis to assess the safety and effectiveness of different doses of BNS to explore a sufficient dose range of BNS in Chinese patients with schizophrenia (SZ). Methods: A 12-week, prospective, observational, single-arm, multicenter, open-label PMS was conducted. In this analysis, we divided the patients from PMS into low, medium to high, and high dose groups based on the dose of BNS they received, with medium to high dose group being the focus. The Brief Psychiatric Rating Scale (BPRS) scores at week 2 or 4, 6 or 8, and 12 were calculated to evaluate the effectiveness of BNS in improving psychiatric symptoms. The safety of BNS was reported as the incidence of adverse drug reactions. Results: 364 patients were included in the medium to high dose group, of which 321 completed the surveillance, with a dropout rate of 11.8%. The mean daily dose was 15.1 ± 1.92 mg. The BPRS total score was 50.1 ± 11.95 at baseline and decreased to 26.6 ± 7.43 at 12 weeks (P < 0.001). When compared with other groups, the median to high dose group achieved significantly more reduction in BPRS score at week 12 (P = 0.004 versus low dose and P = 0.033 versus higher dose). Extrapyramidal symptoms [EPS (46.4%)] were the most common adverse reactions in the medium to high group. The average weight gain during the surveillance was 0.5 ± 2.56 kg and prolactin elevation occurred in 2.2% patients. Most adverse reactions were mild. Conclusions: BNS at medium to high doses (mean 15.1 mg/d) significantly improved symptoms of SZ and was well-tolerated. Most ADRs were mild, and the likelihood of causing metabolic side effects and prolactin elevations was low. Medium to high dose of BNS is a more potent treatment choice for SZ. Trial registration number: ChiCTR2100048734. Date of registration: 2021/07/15 (retrospectively registered). [ABSTRACT FROM AUTHOR]

Due to the rapid development of industrialization and a substantial economy, China has become one of the global hotspots of nitrogen (N) and sulfur (S) deposition following Europe and the USA. Here, we developed a dataset with full coverage of N and S deposition from 2005 to 2020, with multiple statistical models that combine ground-level observations, chemistry transport simulations, satellite-derived vertical columns, and meteorological and geographic variables. Based on the newly developed random forest method, the multi-year averages of dry deposition of oxidized nitrogen (OXN), reduced nitrogen (RDN), and S in China were estimated at 10.4, 14.4, and 16.7 kg N/S ha -1 yr -1 , and the analogous numbers for total deposition were respectively 15.2, 20.2, and 25.9 kg N/S ha -1 yr -1 when wet deposition estimated previously with a generalized additive model (GAM) was included. The dry to wet deposition ratio (Rdry/wet) of N stabilized in earlier years and then gradually increased especially for RDN, while that of S declined for over 10 years and then slightly increased. The RDN to OXN deposition ratio (RRDN/OXN) was estimated to be larger than 1 for the whole research period and clearly larger than that of the USA and Europe, with a continuous decline from 2005 to 2011 and a more prominent rebound afterwards. Compared with the USA and Europe, a more prominent lagging response of OXN and S deposition to precursor emission abatement was found in China. The OXN dry deposition presented a descending gradient from east to west, while the S dry deposition a descending gradient from north to south. After 2012, the OXN and S deposition in eastern China declined faster than the west, attributable to stricter emission controls. Positive correlation was found between regional deposition and emissions, while smaller deposition to emission ratios (D/E) existed in developed eastern China, attributed to more intensive human activities and thereby anthropogenic emissions. [ABSTRACT FROM AUTHOR]

Due to the rapid development of industrialization and substantial economy, China has become one of the global hotspots of nitrogen (N) and sulfur (S) deposition following Europe and the USA. Here, we developed a dataset with full coverage of N and S deposition from 2005 to 2020, with multiple statistical models that combine ground-level observations, chemistry transport simulations, satellite-derived vertical columns, and meteorological and geographic variables. Based on the newly developed random forest method, the multi-year averages of dry deposition of OXN, RDN and S in China were estimated at 10.4, 14.4 and 16.7 kg N/S ha−1 yr−1, and the analogous numbers for total deposition were respectively 15.2, 20.2 and 25.9 kg N/S ha−1 yr−1 when wet deposition estimated previously with a GAM model was included. The Rdry/wet of N stabilized in earlier years and then gradually increased especially for RDN, while that of S declined for over ten years and then slightly increased. RRDN/OXN was estimated to be larger than 1 for the whole research period and clearly larger than that of the USA and Europe, with a continuous decline from 2005 to 2011 and a more prominent rebound afterwards. Compared with the USA and Europe, a more prominent lagging response of OXN and S deposition to precursor emission abatement was found in China. The OXN dry deposition presented a descending gradient from east to west, while the S dry deposition a descending gradient from north to south. After 2012, the OXN and S deposition in eastern China declined faster than the west, attributable to stricter emission controls. Positive correlation was found between regional deposition and emissions, while smaller deposition to emission ratios (D/E) existed in developed eastern China with more intensive human activities. [ABSTRACT FROM AUTHOR]

The volatilization of ammonia (NH 3) from fertilizer application and livestock wastes is an overwhelmingly important pathway of nitrogen losses in agricultural ecosystems and constitutes the largest source of atmospheric NH 3. The volatilization of NH 3 highly depends on environmental and meteorological conditions, however, this phenomenon is poorly described in current emission inventory and atmospheric models. Here, we develop a dynamic NH 3 emission model capable of calculating the NH 3 emission rate interactively with temporal- and spatial-varying meteorological and soil conditions. The NH 3 flux parameterization relies on several meteorological factors and anthropogenic activity including fertilizer application, livestock waste, traffic, residential, and industrial sectors. The model is then embedded into a regional WRF–Chem model and is evaluated against field measurements of NH 3 concentrations, emission flux, and satellite retrievals of column loading. The evaluation shows a substantial improvement in the model performance of NH 3 flux and ambient concentration in China. The model represents the spatial and temporal variations of ambient NH 3 concentration well, indicating the highest emission in the North China Plain (NCP) and Sichuan Basin, especially during summertime. Compared with normal simulations using fixed emission inventory input, this model features superior capability in simulating NH 3 emission flux and concentration during drastic weather changes like frontal activities and precipitation. Such advances in emission quantification also improve the model performance of secondary inorganic aerosol on synoptic scales. While more laboratory and field measurements are still needed for better parameterization of NH 3 volatilization, the seamless coupling of soil emission with meteorology provides a better understanding of NH 3 emission evolution and its contribution to atmospheric chemistry. [ABSTRACT FROM AUTHOR]

Based on the digital elevation data, snow depth and snow cover remote sensing data, this paper divides six snow evolution areas and geographical partitions, extracts the geographical partitions of each evolution area and obtains the geographical characteristics of the evolution area for analysis. The results show that: (1) From 2003 to 2017, the average snow area decreased at a rate of − 0.004, and the average snow depth increased at a rate of 0.03. (2) The snow in the middle altitude hill with shady gentle slope area is the most obvious in the seasonal evolution, and the percentage of this region in the seasonal snow evolution area is 5.46%, the snow depth in the middle altitude hill with sunny and gentle slopes area increased and decreased significantly in the past 15 years, and the percentage of this region in the SD significant changes evolution area was 6.32%. The snow in the low relief middle altitude mountain with shady and moderate slope area not only shows obvious seasonal evolution, but also increases and decreases significantly in snow depth. And the percentage of this region in the seasonal snow significant evolution area is 5.82%. (3) The geographical partitions with the largest area in all evolution areas is the middle altitude hill with sunny and gentle slopes area (4.75%). (4) The geographical partition with the largest variation of snow depth in Tianshan region is the low relief middle altitude mountain with shady and moderate slope area (12.02 cm). (5) The snow accumulation and melting are obvious in the range of 1000–3500 m above altitude, different geomorphology types lead to obvious differences in snow characteristics. The snow melting is most obvious in the gentle slope area of the low topographic relief geomorphology types, and the snow accumulation is most obvious in the steep slope area of the middle relief geomorphology types. [ABSTRACT FROM AUTHOR]

We present a model analysis that quantifies the influence of anthropogenic emission variations on the recent (2005–2015) and future (2030) changes in national scale nitrogen deposition in China and the interacting relationships between their emissions and depositions. We find that the 0.39 Tg N yr−1 increase in the dry deposition of reduced nitrogen (NHx) during 2007–2015 is dominated by the decrease in sulfur dioxides (SO2) emissions, which reduces the formation of ammonium (NH4+) aerosols from gas‐phase ammonia (NH3). Although the decrease in SO2 emissions led to conversion from wet to dry deposition of NHx, the NH4+ wet deposition increased by 0.75 Tg N yr−1 with large interannual variations driven by precipitation. Different from NHx, the oxidized nitrogen (NOy) deposition increased by 1.6 Tg N yr−1 from 2005 to 2011 and decreased by 1.1 Tg N yr−1 from 2011 to 2015, following the changes in nitrogen oxides (NOx) emissions. Based on the national scale emission‐deposition relationship estimated from model sensitivity experiments, we find that future emission control would reduce the NOy deposition by 2.4 ± 0.08 to 3.4 ± 0.12 Tg N yr−1 (49%–73%), but only lead to small decreases of 0.93 ± 0.05 to 1.2 ± 0.06 Tg N yr−1 (9%–14%) in NHx deposition in China from 2015 to 2030. The decrease in NOx and SO2 emissions under future scenarios would enhance the NHx dry deposition over domestic China, diminishing the effectiveness of the NH3 emission control. The results emphasize that stricter strategies for controlling agricultural NH3 emissions should be taken to alleviate the adverse environmental impacts from atmospheric nitrogen deposition. Plain Language Summary: China is a hotspot of atmospheric nitrogen deposition over the world due to rapid industrialization and intensified agricultural production. Based on the atmospheric chemistry model experiments, we quantify the response of nitrogen deposition in China to recent and future changes in anthropogenic emissions. We find that from 2007 to 2015, the increase in NHx dry deposition is dominated by the reduction in sulfur dioxides (SO2) emissions, while the increase in ammonium (NH4+) wet deposition is due to the increase in precipitation. Different from NHx, the NOy deposition peaked around 2011 and then decreased following the nitrogen oxide (NOx) emission reductions. Based on the future emission scenarios, we estimate that the future emission control in China can effectively reduce the NOy deposition by more than 49% but would only lead to a small decrease in NHx deposition in 2030 compared to 2015. This study highlights the importance of stricter strategies for controlling agricultural ammonia (NH3) emissions to alleviate the adverse environmental impacts from atmospheric nitrogen deposition in the future. Key Points: The decrease in SO2 emissions dominated the increase in NHx dry deposition flux from 2007 to 2015 in ChinaThe NOy deposition in China peaked around 2011 and then decreased following the NOx emission reductionsThe future emission control in China would effectively reduce the NOy deposition but only lead to small decrease in NHx deposition in 2030 [ABSTRACT FROM AUTHOR]

Substantial ammonia (NH3) losses from rice production result in poor nitrogen (N) use efficiency and environmental damage. A data synthesis using the published literature (127 studies with 700 paired observations), combined with an incubation experiment using 50 paddy soils from across China, were conducted to improve the current understanding of the NH3 loss from paddy rice and its drivers. The efficacy of the urease inhibitor Limus® for reducing NH3 losses was also evaluated. The mean loss of N, through NH3 volatilization, was 16.2% of the urea-N applied to paddy rice. The largest losses were from double rice cropping systems, and losses increased with the N application rate, surface application of N, unstable N types (ammonium bicarbonate and urea), and high floodwater pH. Under simulated flooded conditions, urea amended with Limus® reduced NH3 loss by 36.6%, compared to urea alone, but floodwater pH had a significant effect on inhibitor efficacy. Key driving factors were air temperature, N application rate, and floodwater pH. The effectiveness and limitations of the inhibitor in NH3 emission mitigation was examined, as well as its basis as one means of N pollution control in paddy rice cropping systems. [ABSTRACT FROM AUTHOR]

Lake Erhai is a potentially phosphorus (P)-limited lake and its water quality may have been affected by atmospheric P deposition. However, there have been few studies on atmospheric P deposition in this lake. In this study, we established five wet deposition monitoring sites and two dry deposition monitoring sites around Lake Erhai to quantify the wet and dry deposition of total phosphorus (TP), including dissolved inorganic phosphorus (DIP), dissolved organic phosphorus (DOP) and particulate phosphorus (PP) from July 2022 to June 2023. Wet deposition fluxes of P species were collected by automatic rainfall collection instrument, and dry deposition fluxes were estimated using airborne concentration measurements and inferential models. The results reveal that among the different P components, DOP had the highest contribution (50%) to wet TP deposition (average all sites 12.7 ± 0.7 mg P m2/yr), followed by PP (40%) and DIP (10%). Similarly, DOP (51%) was the major contributor to dry TP deposition (average two sites 2.4 ± 0.9 mg P m2/yr), followed by DIP (35%) and PP (14%). Wet deposition dominated the annual total TP deposition (wet plus dry), accounting for approximately 83%. The key seasons for dry deposition were spring and autumn, which accounted for 64% of the annual total dry TP deposition. In comparison, wet deposition was significantly higher in the summer, accounting for 73% of the annual total wet TP deposition. The results of the potential source contribution function and concentration-weighted trajectories analysis indicate that local source emission and long-range transport from surrounding cities jointly exerted a substantial influence on aerosol P concentrations, particularly in the eastern and northwestern regions of the lake. These findings provide a comprehensive understanding of the different P components in atmospheric deposition, which is beneficial for developing effective strategies to manage the P cycle in Lake Erhai. [Display omitted] • Wet and dry fluxes of P were 12.7 and 2.4 mg P/m2/yr in Lake Erhai, respectively. • DOP contributed 50% and 51% of total wet and dry P deposition fluxes, respectively. • Wet deposition peaked in summer, while dry deposition peaked in autumn or spring. • Total TDP deposition flux accounted for approximately 7% of the riverine TDP inputs. • Local emission sources and regional transport jointly affected P deposition. [ABSTRACT FROM AUTHOR]

Ammonia (NH 3) is the most important alkaline gas in the atmosphere, which has negative effects on biodiversity, ecosystems, soil acidification and human health. China has the largest NH 3 emissions globally, mainly associated with agricultural sources including nitrogen fertilizer and livestock. However, there is still a limited number of ground monitoring sites in China, hindering our understanding of both surface NH 3 concentrations and emissions. In this study, using the polar-orbiting satellite (Infrared Atmospheric Sounding Interferometer – IASI) and Fengyun-4A Geostationary Interferometric Infrared Sounder (GIIRS), we analyzed the changes in hourly NH 3 concentrations and estimated surface NH 3 concentrations and NH 3 emissions in China. GIIRS-derived NH 3 concentrations in the daytime were generally higher than those at night, with high values during 10:00–16:00 local time. Satellite-derived surface NH 3 concentrations were generally consistent with the ground observations, with R -square at 0.72 and slope equal to 1.03. Satellite-based NH 3 emissions ranged from 12.17 to 17.77 Tg N yr -1 during 2008–2019. Spatially, high values of NH 3 emissions mainly occurred in the North China Plain, Northeast China and the Sichuan Basin, while low values were mainly distributed in West China (Qinghai–Tibet Plateau). Our study shows a high predictive power of using satellite data to estimate surface NH 3 concentrations and NH 3 emissions over multiple temporal and spatial scales, which provides an important reference for understanding NH 3 changes over China. [ABSTRACT FROM AUTHOR]

Terrestrial ecosystems in China receive the world's largest amount of reactive nitrogen (N) deposition. Recent controls on nitrogen oxides (NOx = NO + NO2) emissions in China to tackle air pollution are expected to decrease N deposition, yet the observed N deposition fluxes remain almost stagnant. Here we show that the effectiveness of NOx emission controls for reducing oxidized N (NOy = NOx + its oxidation products) deposition is unforeseen in Eastern China, with one-unit reduction in NOx emission leading to only 55‒76% reductions in NOy-N deposition, as opposed to the high effectiveness (around 100%) in both Southern China and the United States. Using an atmospheric chemical transport model, we demonstrate that this unexpected weakened response of N deposition is attributable to the enhanced atmospheric oxidizing capacity by NOx emissions reductions. The decline in N deposition could bear a penalty on terrestrial carbon sinks and should be taken into account when developing pathways for China's carbon neutrality. Recent vigorous controls in anthropogenic nitrogen oxide emissions in China cannot result in proportionate decreases in regional atmospheric nitrogen deposition. Enhanced atmospheric oxidizing capacity offsets those reductions of precursor emissions. [ABSTRACT FROM AUTHOR]

The Chinese government recently proposed ammonia (NH 3) emission reductions (but without a specific national target) as a strategic option to mitigate fine particulate matter (PM 2.5) pollution. We combined a meta-analysis of nationwide measurements and air quality modeling to identify efficiency gains by striking a balance between controlling NH 3 and acid gas (SO 2 and NO x) emissions. We found that PM 2.5 concentrations decreased from 2000 to 2019, but annual mean PM 2.5 concentrations still exceeded 35 µ g m -3 at 74 % of 1498 monitoring sites during 2015–2019. The concentration of PM 2.5 and its components were significantly higher (16 %–195 %) on hazy days than on non-hazy days. Compared with mean values of other components, this difference was more significant for the secondary inorganic ions SO 42- , NO 3- , and NH 4+ (average increase 98 %). While sulfate concentrations significantly decreased over this period, no significant change was observed for nitrate and ammonium concentrations. Model simulations indicate that the effectiveness of a 50 % NH 3 emission reduction for controlling secondary inorganic aerosol (SIA) concentrations decreased from 2010 to 2017 in four megacity clusters of eastern China, simulated for the month of January under fixed meteorological conditions (2010). Although the effectiveness further declined in 2020 for simulations including the natural experiment of substantial reductions in acid gas emissions during the COVID-19 pandemic, the resulting reductions in SIA concentrations were on average 20.8 % lower than those in 2017. In addition, the reduction in SIA concentrations in 2017 was greater for 50 % acid gas reductions than for the 50 % NH 3 emission reductions. Our findings indicate that persistent secondary inorganic aerosol pollution in China is limited by emissions of acid gases, while an additional control of NH 3 emissions would become more important as reductions of SO 2 and NO x emissions progress. [ABSTRACT FROM AUTHOR]

In Southwestern China, there exists deep river valleys and abundant rainfall, which leads to a large number of reverse-dip rock slopes. In order to investigate the evolution characteristics of toppling deformation of reverse-dip slope under the influence of rainfall, and a typical reverse-dip slope was taken as an engineering case. Firstly, the temporal and spatial evolution nephogram of toppling displacement under different rainfall was obtained based on the discrete surface displacement monitoring data of bank slope. Then, taking bank slope, gully buffer zone, and development degree of bank slope as development characteristics based on geological field survey, afterward, the evolution characteristics in different strong deformation zones were analyzed by superimposing the development characteristic partition and the spatial and temporal displacement nephogram. The results showed that the horizontal displacement mainly occurred on the right front and middle rear of the bank slope while large vertical displacement occurred on the middle of the bank slope under the influence of rainfall. As the rainfall increased to the maximum, the toppling deformation reached the peak, and vertical displacement was more sensitive to the rainfall than horizontal displacement. After the superposition, the largest strong deformation zone was located in the middle and rear part of the bank slope, which is characterized by medium and high slope and mature stage and 50 m gully buffer zone. This paper explores the deformation and failure process of reverse-dip rock slope considering the change of rainfall through real displacement monitoring data and focuses on the real deformation evolution law of each characteristic zone combined with different development characteristics partition. [ABSTRACT FROM AUTHOR]

Aims Litter is frequently buried in the soil in alpine grasslands due to grassland degradation, serious rodent infestation and frequent strong winds. However, the effects of various litter positions on litter decomposition rates and nutrient dynamics under nitrogen (N) enrichment in such areas remain unknown. Methods A field experiment was performed in the alpine grasslands of northwest China to investigate the influence of litter position (surface, buried in the soil and standing) and N enrichment on litter decomposition, using data from two dominant grass species (Festuca ovina and Leymus tianschanicus) in control and N-enriched plots. Important Findings Litter decomposition rates were much faster in buried litter and slower in standing litter than in surface litter. N enrichment significantly affected litter quality and then influenced decomposition. But no significant differences in litter mass remaining were observed between control and N-enriched soil burial. These results indicated that N enrichment significantly affected litter decomposition by changes in litter quality. In addition, all litter exhibited net carbon (C) and phosphorus (P) release regardless of treatments. Litter exhibited net N accumulation for litter from the control plots but showed N release for litter from N enrichment plots. These suggested that litter decomposition can be limited by N and N enrichment influenced N cycling of litter. Current study presented direct evidence that soil buried litter exhibited faster mass loss and C release, and that soil burial can be a candidate explanation why litter decomposes faster than expected in dryland. [ABSTRACT FROM AUTHOR]

Background: The outbreak of Coronavirus Disease 2019(COVID-19) caused psychological stress in Chinese adults population. But we are unaware of whether the pandemic causes psychological stress on children. Methods: We used the Children's Impact of Event Scale questionnaire (CRIES-13) to investigate the degree of Post-traumatic Stress (PTSD) symptoms caused by the pandemic in students selected from schools in Sichuan, Jiangsu, Henan, Yunnan, and Chongqing provinces of China. Results: A total of 7769 students(3692 male and 4077 female), aged 8–18 years, were enrolled in the study, comprising 1214 in primary schools, 2799 in junior high schools and 3756 in senior high schools. A total of 1639 students (21.1%) had severe psychological stress reactions. A large proportion of senior high school students (23.3%) experienced severe psychological stress, and they had the highest median total CRIES-13 score. Female students were more likely to experience severe psychological stress and had higher median CRIES-13 total scores than males. Conclusion: COVID-19 has placed psychological stresses on primary and secondary school students in China. These stresses are more likely to reach severe levels among female students and senior high school students. [ABSTRACT FROM AUTHOR]

Atmospheric nitrogen (N) deposition in China has been the largest worldwide. Yet the impacts of atmospheric N deposition on soil N2O emissions were often ignored by previous studies. Thus, we investigated how N deposition affected N2O emissions over China using the process-based model (DNDC, DeNitrification-DeComposition). Total soil N inputs were 194 kg N ha−1 in agricultural systems over China in 2010, including chemical N fertilizer (78%), atmospheric N deposition (12%), and crop residues N (10%). Annual N2O emissions induced by N deposition were estimated at 97 Gg N, occupying 43% of total soil N2O emissions (228 Gg N) in agricultural systems over China. In particular, the largest N2O emissions caused by atmospheric N deposition were found in South China, followed by North China Plain and Southwest China. The efficiency of N deposition generating N2O emissions (3.0%) over China was 4 times than that of N fertilizer (0.7%). N2O emissions induced by N deposition increased from 81 Gg in 2000 to 93 Gg in 2014 (by 1% yr−1), which was consistent with the long-term trend of N deposition. This suggests N deposition accelerated soil N2O emissions largely contributing to global warming. Our results also indicated that 62% and 10% of soil N2O emissions were reduced by applying a nitrification inhibitor and N fertilizer with 20% decrease. We highlight the significance of considering N deposition in determining total soil N2O emissions over China. The results provide an important scientific basis for the prediction of greenhouse effect caused by N deposition over China. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) can significantly influence the soil carbon cycle, however, their impacts on desert soils are still unclear. Here, a field control experiment, using in‐growth mesocosms, was conducted to quantitatively assess the contribution of AMF and ephemeral plants to ecosystem respiration (Re) and methane (CH4) flux in the Gurbantunggut Desert in China, from April to May 2017. Ephemeral plant biomass was significantly increased by AMF infection. Re was significantly positively correlated with AMF infection rate, whereas CH4 flux was significantly negatively correlated. The contribution of AMF to Re was up to 24%, comparable to the contribution of non‐AMF microbial respiration, which accounted for up to 36%, whereas the respiration of ephemeral plants accounted for 40%. Variation in Re was most strongly associated with soil organic carbon and soil available potassium concentrations and soil temperature. Non‐AMF microorganisms accounted for most of the CH4 flux (up to 85%). In contrast, AMF only accounted for 15% of total CH4 flux. The CH4 flux was significantly influenced by soil NO3−‐N content, soil moisture, soil temperature and soil NH4+‐N content. Overall, AMF significantly influenced Re and CH4 flux, and also enhanced the growth of ephemeral plants, which have an important role in the carbon cycle in desert ecosystems. [ABSTRACT FROM AUTHOR]

Temperate desert soils are an important source of atmospheric nitrous oxide (N2O). However, it is uncertain how N2O emissions respond to warming, increased rainfall and nitrogen (N) addition in such soils. A multifactorial field manipulation study was carried out in the Gurbantunggut Desert, China's second largest desert, to investigate how these factors influence desert soil N2O emissions and to assess inter‐year variation. In our 3‐year study, under current climatic conditions, the annual flux of N2O in this temperate desert soil was 0.13 ± 0.02 kg N ha−1 yr−1, with the period of no plant growth contributing 43% of the annual emission. Surprisingly, there was no significant change in annual N2O flux under warming (+1°C) or increased precipitation (30%, +60 mm yr−1). In contrast, N2O emissions were significantly affected by extreme drought followed by precipitation. Additional N input, at 30 or 60 kg N ha−1 yr−1, greatly elevated annual N2O emission by 55–133%. The combined impact of N deposition and increasing rainfall on N2O emission was greater than that of any single factor, except for N deposition. This suggests that N2O emissions in this desert are driven primarily by soil available N content and are less sensitive to variations in soil temperature and moisture. [ABSTRACT FROM AUTHOR]

It is a puzzle as to why more severe haze formed during the New Year Holiday in 2020 (NYH‐20), when China was in an unprecedented state of shutdown to contain the coronavirus (COVID‐19) outbreak, than in 2019 (NYH‐19). We performed a comprehensive measurement and modeling analysis of the aerosol chemistry and physics at multiple sites in China (mainly in Shanghai) before, during, and after NYH‐19 and NYH‐20. Much higher secondary aerosol fraction in PM2.5 were observed during NYH‐20 (73%) than during NYH‐19 (59%). During NYH‐20, PM2.5 levels correlated significantly with the oxidation ratio of nitrogen (r2 = 0.77, p < 0.01), and aged particles from northern China were found to impede atmospheric new particle formation and growth in Shanghai. A markedly enhanced efficiency of nitrate aerosol formation was observed along the transport pathways during NYH‐20, despite the overall low atmospheric NO2 levels. Plain Language Summary: In China, there are multiple cases (e.g., the 2008 Summer Olympics in Beijing and the 2010 World Expo in Shanghai) when combustion‐related emissions (e.g., NOx) were actively, and successfully, reduced to transiently improve air quality. During the extended Chinese Lunar New Year holiday in 2020 (between 24 January and 10 February), whole China was in an unprecedented state of shutdown, because most people were contained in their homes to reduce the spread of the novel coronavirus disease (COVID‐19). Mobility, energy demand, and industrial output remained far below their normal levels. Nevertheless, widespread haze pollution still occurred over Eastern China. To elucidate haze formation mechanisms, we performed comprehensive and continuous measurements of aerosol chemistry and physics in and out of Shanghai before, during, and after the Chinese New Year Holiday in 2019 and 2020, respectively. We argue that the synergistic effects of long‐range transport and atmospheric chemistry leading to the efficient conversion of NOx to particulate nitrate were the key of haze formation during the Chinese New Year Holiday of the COVID‐19 outbreak in Shanghai. Key Points: Higher concentrations and distinct compositions of aerosol particles were observed during the COVID‐19 shutdownFast formation of secondary inorganic aerosol contributed to high aerosol mass loadingLonger‐range, regional transport facilitated and enhanced particulate nitrate formation [ABSTRACT FROM AUTHOR]

This case study was performed to determine whether the pollutants in water of urban park could bring health risk to human engaging in water-related activities such as swimming and provide evidence demonstrating the critical need for strengthened recreational water resources management of urban park. TN, NH4+-N, TP, Cu, Mn, Zn, Se, Pb, As, Cd and Cr(VI) contents were determined to describe the spatial distribution of contaminations; sources apportionment with the method of correlation analysis, factor analysis and cluster analysis were followed by health risk assessment for swimmers of different age groups. The results reveal that element contents in all sites do not exceed Chinese standard for swimming area and European Commission standard for surface water; all detected elements except Cr(VI) have a tendency to accumulate in the location of lake crossing bridge; Mn and Zn are considered to have the same pollution source including geogenic and anthropogenic sources by multivariable analysis. Carcinogenic risks of different age groups descend in the same order with non-carcinogenic risks. Among all elements, Zn and Mn contribute the lowest non-carcinogenic risk (5.1940E-06) and the highest non-carcinogenic risk (7.9921E-04) through skin contact pathway, respectively. The total average personal risk for swimmers in swimming area is 1.9693E-03, and this site is not suitable for swimming. Overall, it is possible that swimmers are exposed to risk via the dermal route when carrying out water-related activities, it is recommended that necessary precautions and management should be taken in other similar locations around the world. [ABSTRACT FROM AUTHOR]

Desert soils are a significant global sink for methane (CH4). However, it remains unclear how CH4 uptake in temperate deserts could respond to elevated precipitation, nitrogen (N) deposition and warming. An in situ field experiment was conducted to investigate these effects on CH4 uptake in the Gurbantunggut Desert, northwest China, from September 2014 to August 2017. This desert was a weak sink for CH4 (0.83 kg C ha−1 year−1) over this period, with the non-growing season (November–March) accounting for 30.5% of the annual CH4 uptake. Pulse CH4 uptake was found to result from increased water addition (by 30% or 60 mm year−1) and low N deposition (30 kg N ha−1 year−1) which enhanced annual CH4 uptake by 62.3 and 52.6%, respectively. However, no significant impact of high N deposition (60 kg N ha−1 year−1) was found. Warming in open topped chambers (OTCs) had a variable effect on CH4 uptake, which mainly depended on variation in soil moisture. The response in CH4 uptake to the interaction between water and N addition was less than that for the individual factors, except under conditions of warming. In addition, CH4 uptake was significantly positively correlated to water-filled pore space (WFPS), differing from observations in forest and grassland ecosystems. Structural equation modeling indicated that CH4 uptake was significantly enhanced by soil moisture and the underground biomass of ephemerals. Overall, the CH4 sink of this desert was significantly enhanced by increasing precipitation and low N deposition, rather than warming, which may become a feedback for future climate. [ABSTRACT FROM AUTHOR]

Surface water is the main source of water for human life and production. The quality of water affects living conditions and the overall health of people. Ecological protection and restoration engineering technology, combining ecological revetment and an ecological floating bed, is applied to a selected shallow beach experimentation area of a reservoir water source area in Northeast China. According to local conditions, the ecological revetment plants were identified as Goosegrass, sedges, and water grasses, and other local species of Polygonum hydropiper bagen, reeds, and bulrushes were identified as ecological floating bed plants. Regular monitoring of water quality in the experimentation area and a control area showed that the ecological protection and restoration technology can effectively reduce the concentrations of BOD5 (five day biochemical oxygen demand), COD (chemical oxygen demand), TN, NH3-N, NO3−-N, TP, TDP, Mn, Zn, Fe, Pb, total coliforms, and other indicators of surface water in the experimentation area. The BOD5, COD, Max TN, NH3-N, NO3−-N, TP, and TDP reduction rates were 84.76%, 57.14%, 86.76%, 83.78%, 89.26%, 94.02%, and 95.89%, respectively, with the implementation of water pollution prevention and the purifying shoal. [ABSTRACT FROM AUTHOR]

Ammonia (NH3), as an alkaline gas in the atmosphere, can cause direct or indirect effects on the air quality, soil acidification, climate change and human health. Estimating surface NH3 concentrations is critically important for modeling the dry deposition of NH3 and for modeling the formation of ammonium nitrate, which have important impacts on the natural environment. However, sparse monitoring sites make it challenging and difficult to understand the global distribution of surface NH3 concentrations in both time and space. We estimated the global surface NH3 concentrations for the years of 2008–2016 using satellite NH3 retrievals combining vertical profiles from GEOS-Chem. The accuracy assessment indicates that the satellite-based approach has achieved a high predictive power for annual surface NH3 concentrations compared with the measurements of all sites in China, the US and Europe (R2=0.76 and RMSE = 1.50 µ g N m -3). The satellite-derived surface NH3 concentrations had higher consistency with the ground-based measurements in China (R2=0.71 and RMSE = 2.6 µ g N m -3) than the US (R2=0.45 and RMSE = 0.76 µ g N m -3) and Europe (R2=0.45 and RMSE = 0.86 µ g N m -3) at a yearly scale. Annual surface NH3 concentrations higher than 6 µ g N m -3 are mainly concentrated in the North China Plain of China and northern India, followed by 2–6 µ g N m -3 mainly in southern and northeastern China, India, western Europe, and the eastern United States (US). High surface NH3 concentrations were found in the croplands in China, the US and Europe, and surface NH3 concentrations in the croplands in China were approximately double those in the croplands in the US and Europe. The linear trend analysis shows that an increase rate of surface NH3 concentrations (> 0.2 µ g N m -3 yr -1) appeared in eastern China during 2008–2016, and a middle increase rate (0.1–0.2 µ g N m -3 yr -1) occurred in northern Xinjiang over China. NH3 increase was also found in agricultural regions in the central and eastern US with an annual increase rate of lower than 0.10 µ g N m -3 yr -1. The satellite-derived surface NH3 concentrations help us to determine the NH3 pollution status in the areas without monitoring sites and to estimate the dry deposition of NH3 in the future. [ABSTRACT FROM AUTHOR]

Nitrogen (N) fertilizer application and atmospheric N deposition will profoundly affect greenhouse gas (GHGs) emissions, especially nitrous oxide (N 2 O) and methane (CH 4) fluxes and ecosystem respiration (R e , i.e. CO 2 emissions). However, the impacts of long-term N inputs and the often associated N-induced soil acidification on GHG fluxes in arid and semi-arid ecosystems, especially temperate grasslands, are still uncertain. An in situ experiment was conducted to investigate the effect of long-term (13-years) N addition on N 2 O and CH 4 fluxes and R e from a temperate grassland in Inner Mongolia, northeast China, from April 2017 to October 2018. Soil pH values in the 0–5 cm layer receiving 120 (N 120) and 240 (N 240) kg N ha−1 decreased from 7.12 to 4.37 and 4.18, respectively, after 13 years of N inputs. Soil CH 4 uptake was significantly reduced, but N 2 O emission was enhanced significantly by N addition. However, N addition had no impact on R e. Structural Equation Modeling indicated that soil NH 4 +-N content was the dominant control of N 2 O emissions, but with less effect of the decreasing pH. In contrast, CH 4 uptake was generally controlled by soil pH and NO 3 −-N content, and R e by forb biomass. The measured changes in N 2 O and CH 4 fluxes and R e from temperate grassland will have a profoundly impact on climate change. An in situ experiment was conducted to investigate the effect of long-term (13-years) increased N addition on N 2 O and CH 4 fluxes and R e from a temperate grassland in Inner Mongolia, northeast China, from April 2017 to October 2018. Soil pH values in the 0–5 cm layer receiving 120 (N 120) and 240 (N 240) kg N ha−1 decreased from 7.12 to 4.37 and 4.18, respectively, after 13 years of N inputs. Soil CH 4 uptake was significantly reduced, but N 2 O emission was enhanced significantly by N addition. However, N addition had no impact on R e. Structural Equation Modeling indicated that soil NH 4 +-N content was the dominant control of N 2 O emissions, but with less effect of the decreasing pH. In contrast, CH 4 uptake was generally controlled by soil pH and NO 3 −-N content, and R e by forb biomass. The measured changes in N 2 O and CH 4 fluxes and R e from temperate grassland will have a profoundly impact on climate change. Image 1 • We studied the impacts of long-term N addition on a temperate grassland. • CH 4 uptake was significantly reduced by long-term N addition. • N 2 O emission was controlled mainly by soil ammonium N rather than soil pH. • CH 4 uptake was affected mainly by soil pH and nitrate N content. • Ecosystem respiration was impacted mainly by production of forbs. Long-term increased N addition significantly reduced CH 4 uptake and enhanced N 2 O emissions, but had no significant impact on ecosystem respiration in temperate grassland. [ABSTRACT FROM AUTHOR]

The article analyzes whether China's Belt and Road Initiative (BRI) is a geopolitical strategy. Topics discussed are responsibility of China in reviving the ancient Silk Road and goal of BRI to promote inclusive development towards globalization, concept of Community of Shared Future as manifestation of Chinese Harmonious and Syncretic Culture that aims for geoeconomy and geocivilization, and misperceptions about the BRI.

Five-year (2011-2015) measurements of gaseous NH3, NO2, and HNO3 and particulate NH4+ and NO3- in air and/or precipitation were conducted at 27 sites in the Nationwide Nitrogen Deposition Monitoring Network (NNDMN) to better understand spatial and temporal (seasonal and annual) characteristics of reactive nitrogen (Nr) concentrations and deposition in eastern China. Our observations reveal annual average concentrations (16.4-32.6 µgN m-3), dry deposition fluxes (15.8-31.7 kg N ha-1 yr-1), and wet/bulk deposition fluxes (18.4-28.0 kg N ha-1 yr-1) based on land use, ranked as urban > rural > background sites. Annual concentrations and dry deposition fluxes of each Nr species in air were comparable at urban and background sites in northern and southern regions, but were significantly higher at northern rural sites. These results, together with good agreement between spatial distributions of NH3 and NO2 concentrations determined from ground measurements and satellite observations, demonstrate that atmospheric Nr pollution is heavier in the northern region than in the southern region. No significant inter-annual trends were found in the annual Nr dry and wet/bulk N deposition at almost all of the selected sites. A lack of significant changes in annual averages between the 2013-2015 and 2011-2012 periods for all land use types suggests that any effects of current emission controls are not yet apparent in Nr pollution and deposition in the region. Ambient concentrations of total Nr exhibited non-significant seasonal variation at all land use types, although significant seasonal variations were found for individual Nr species (e.g. NH3, NO2, and pNO3-) in most cases. In contrast, dry deposition of total Nr exhibited a consistent and significant seasonal variation at all land use types, with the highest fluxes in summer and the lowest in winter. Based on sensitivity tests by the GEOS-Chem model, we found that NH3 emissions from fertilizer use (including chemical and organic fertilizers) were the largest contributor (36 %) to total inorganic Nr deposition over eastern China. Our results not only improve the understanding of spatial--temporal variations of Nr concentrations and deposition in this pollution hotspot, but also provide useful information for policy-makers that mitigation of NH3 emissions should be a priority to tackle serious N deposition in eastern China. [ABSTRACT FROM AUTHOR]

We applied the adapted model VSD + to assess cropland acidification in four typical Chinese cropping systems (single Maize (M), Wheat-Maize (W-M), Wheat-Rice (W-R) and Rice-Rice (R-R)) on dominant soils in view of its potential threat to grain production. By considering the current situation and possible improvements in field (nutrient) management, five scenarios were designed: i) Business as usual (BAU); ii) No nitrogen (N) fertilizer increase after 2020 (N2020); iii) 100% crop residues return to cropland (100%RR); iv) manure N was applied to replace 30% of chemical N fertilizer (30%MR) and v) Integrated N2020 and 30%MR with 100%RR after 2020 (INMR). Results illustrated that in the investigated calcareous soils, the calcium carbonate buffering system can keep pH at a high level for > 150 years. In non-calcareous soils, a moderate to strong decline in both base saturation and pH is predicted for the coming decades in the BAU scenario. We predicted that approximately 13% of the considered croplands may suffer from Al toxicity in 2050 following the BAU scenario. The N2020, 100%RR and 30%MR scenarios reduce the acidification rates by 16%, 47% and 99%, respectively, compared to BAU. INMR is the most effective strategy on reducing acidification and leads to no Al toxicity in croplands in 2050. Both improved manure and field management are required to manage acidification in wheat-maize cropping system. [ABSTRACT FROM AUTHOR]

The fast economic development of southwest China has resulted in significant increases in the concentrations of reactive nitrogen (Nr) in the atmosphere. In this study, an urban (Chengdu, CD), suburban (Shifang, SF) and agriculture (Yanting, YT) – dominated location in the Sichuan Province, southwest China, were selected to investigate the atmospheric composition of Nr, their concentrations and deposition rates. We measured Nr concentrations in precipitation (NH 4 + , NO 3 − and organic N (DON)), the gas phase (NH 3 and NO 2 ), and the aerosol particles (PM 2.5 ), and calculated their fluxes over a two year period (2014–2016). Total annual N deposition rates were 49.2, 44.7 and 19.8 kg N ha −1 yr −1 at CD, SF and YT, respectively. Ammonia concentrations were larger at the urban and suburban sites than the agricultural site (12.2, 14.9, and 4.9 μg N m −3 at CD, SF and YT, respectively). This is consistent with the multitude of larger sources of NH 3 , including city garbage, livestock and traffic, in the urban and suburban areas. Monthly NO 2 concentrations were lower in warmer compared to the colder months, but seasonal differences were insignificant. Daily PM 2.5 concentrations ranged from 7.7 to 236.0, 5.0–210.4 and 4.2–128.4 μg m −3 at CD, SF and YT, respectively, and showed significant correlations with fine particulate NH 4 + and NO 3 − concentrations. Ratios of reduced to oxidized N were in the range of 1.6–2.7. This implies that the control of reduced Nr especially in urban environments is needed to improve local air quality. [ABSTRACT FROM AUTHOR]

Current estimates of agricultural ammonia (NH3) emissions in China differ by more than a factor of 2, hindering our understanding of their environmental consequences. Here we apply both bottom-up statistical and top-down inversion methods to quantify NH3 emissions from agriculture in China for the year 2008.We first assimilate satellite observations of NH3 column concentration from the Tropospheric Emission Spectrometer (TES) using the GEOS-Chem adjoint model to optimize Chinese anthropogenic NH3 emissions at the 1=2° ×2/3° horizontal resolution for March- October 2008. Optimized emissions show a strong summer peak, with emissions about 50% higher in summer than spring and fall, which is underestimated in current bottom-up NH3 emission estimates. To reconcile the latter with the topdown results, we revisit the processes of agricultural NH3 emissions and develop an improved bottom-up inventory of Chinese NH3 emissions from fertilizer application and livestock waste at the 1=2° ×2=3° resolution. Our bottom-up emission inventory includes more detailed information on crop-specific fertilizer application practices and better accounts for meteorological modulation of NH3 emission factors in China. We find that annual anthropogenic NH3 emissions are 11.7 Tg for 2008, with 5.05 Tg from fertilizer application and 5.31 Tg from livestock waste. The two sources together account for 88% of total anthropogenic NH3 emissions in China. Our bottom-up emission estimates also show a distinct seasonality peaking in summer, consistent with topdown results from the satellite-based inversion. Further evaluations using surface network measurements show that the model driven by our bottom-up emissions reproduces the observed spatial and seasonal variations of NH3 gas concentrations and ammonium (NH+ ) wet deposition fluxes over China well, providing additional credibility to the improvements we have made to our agricultural NH4 ) wet deposition fluxes over China well, providing additional credibility to the improvements we have made to our agricultural NH3 emission inventory. [ABSTRACT FROM AUTHOR]

Objective: Severe mental illness (SMI) represents major social and public health problem in China, especially in low- or middle-income regions. We aim to assess the prevalence and distribution of SMI in Hunan province in central China. Methods: Multistage stratified random sampling methods were used to select qualified subjects in 123 districts and counties in Hunan province. 89465 individuals were randomly identified, and 72999 (81.6%) completed the supplemental 12-Item General Health Questionnaire (GHQ-12) and Cue questionnaire of psychiatric abnormal behaviors. 6082 suspected individuals having high or moderate risk, or psychiatric cues, were administered the Structured Clinical Interview for DSM-IV Axis I disorders (SCID-I) by psychiatrists. Results: 720 respondents were definitely diagnosed as SMI. The 1-month and lifetime prevalence was 9.35‰ and 10.10‰, respectively. The most frequent SMI was schizophrenia, followed by bipolar disorder, intellectual disability, epileptic mental disorder, paranoid psychosis and schizoaffective disorders, with 1-month prevalence ranging from 0.11‰ to 6.50‰ and lifetime prevalence ranging from 0.24‰ to 6.86‰. Multivariate logistic regression analysis revealed that lower education, farmer occupation, retirees or jobless/unemployed, unmarried or divorced and age of 30–64 years old were major factors that associated with the increased risk of SMI. In addition, only 33.3% of 528 patients who completed questionnaire sought help in psychiatric institutions, and up to 51.7% of 720 patients were not referred to the SMI management system in Hunan province. Conclusions: These findings provided a large-scale prevalence data of SMI in a provincial sample of China. The psychiatric disorders brought economical and psychological burden for family and society, which may shed light on the significance of scaling up province-wide mental health service and strengthening the SMI management. [ABSTRACT FROM AUTHOR]

Machine learning (ML) is an advanced computer algorithm that simulates the human learning process to solve problems. With an explosion of monitoring data and the increasing demand for fast and accurate prediction, ML models have been rapidly developed and applied in air pollution research. In order to explore the status of ML applications in air pollution research, a bibliometric analysis was made based on 2962 articles published from 1990 to 2021. The number of publications increased sharply after 2017, comprising approximately 75% of the total. Institutions in China and United States contributed half of all publications with most research being conducted by individual groups rather than global collaborations. Cluster analysis revealed four main research topics for the application of ML: chemical characterization of pollutants, short-term forecasting, detection improvement and optimizing emission control. The rapid development of ML algorithms has increased the capability to explore the chemical characteristics of multiple pollutants, analyze chemical reactions and their driving factors, and simulate scenarios. Combined with multi-field data, ML models are a powerful tool for analyzing atmospheric chemical processes and evaluating the management of air quality and deserve greater attention in future. [Display omitted] • A bibliometric analysis of machine learning in atmospheric research was made. • The most influential research groups and journals were revealed. • Four main research focuses were revealed. • Developments of machine learning applications were proposed. [ABSTRACT FROM AUTHOR]

China is regarded as one of the nitrogen deposition hotspots in the world. Measurements to-date have focused mainly on the North China Plain, ignoring the fact that atmospheric chemical and physical properties vary across the country and that there may be other hotspots regions that should be investigated. For this reason we have conducted a six year study, measuring the bulk deposition of reduced (NH 4 -N), oxidized (NO 3 -N), and dissolved organic nitrogen (DON) at three contrasting sites in the Sichuan province, southwest China. The study sites were a high altitude forest in the Gongga Mountains (GG), an agriculture dominated region in Yanting (YT) and an urban site in the mega city Chengdu (CD). The annual average bulk deposition fluxes of total dissolved nitrogen (TDN) were 7.4, 23.1 and 36.6 kg N ha −1 yr −1 at GG, YT and CD sites, respectively, during the study period 2008 to 2013. The contributions of NH 4 -N, NO 3 -N and DON to the TDN were in the range of 48.4–57.8%, 28.8–43.7%, and 8.0–15.6%, respectively. DON bulk deposition was mainly dominated by agricultural activities. TDN bulk deposition fluxes showed increasing trends at the agricultural and urban sites from 2008 to 2013, but there was little change at the remote forest (GG) site. While reduced N dominated bulk N deposition at all the three sites, its contribution showed a decreasing trend, suggesting a gradual increase in the importance of oxidized N. These results reveal the value of long term monitoring in detecting changes in the atmospheric chemical composition of this rapidly changing region, and their inclusion in the policy debate regarding which sources should be controlled in order to reduce the long term impacts of N deposition, especially for southwest China, where there are few measurements of N deposition. [ABSTRACT FROM AUTHOR]

Paddy fields in China contributed to one third of the global cropland ammonia (NH 3) emission inventory, while rice accounted for half of cereal consumption, necessitating exhaustive considerations of the balance between NH 3 emissions abatement and food demand. The concept of yield-scaled emission intensity (emissions per unit crop production) has the potential to guide sustainable intensification strategies, yet its application to NH 3 emissions remains poorly understood. Here, by constructing novel crop-specific models for single rice production and NH 3 emissions in the Middle and Lower Yangtze River Basin (LYRB) as a case study, the relationships between fertilizer N application and yield-scaled NH 3 were estimated. Contrary to our hypothesis of a tipping point, our results showed that yield-scaled NH 3 curves could not directly identify optimal nitrogen (N) rates. However, the benefit of lower N fertilizer rate on NH 3 abatement consistently outweighed the risk of yield loss. The exponential relationships between yield-scaled NH 3 and N surplus allowed us to estimate the N surplus criterion as 15.6 kg N ha−1 (or 190 kg N ha−1 fertilizer N rate) for the LYRB. Under the N surplus criterion, NH 3 emissions can be reduced by 23–27% without severely impacting rice yield, compared to the N rate required for the highest yield. Moreover, five major controlling factors for yield-scaled NH 3 were estimated by random forest models, ranked in order of importance as N rate, total N, K rate, mean annual precipitation, and soil organic carbon. Among the agricultural practices (irrigation, tillage, and fertilizer management), deep placement was the most effective measure to reduce yield-scaled NH 3, showing 48% reduction potential, followed by proper N splitting frequency (43%). Overall, this study highlights the efficacy of N application optimization and targeted farm management in mitigating NH 3 emission while maintaining crop productivity. [Display omitted] • Yield-scaled NH 3 cannot directly guide N rate due to high abatement efficacy. • The Yield-scaled NH 3 –N surplus criterion reduces NH 3 emissions by 23–27%. • Five key factors contributing to spatial variations were unraveled. • Deep placement and optimal splitting frequency perform best in yield-scaled NH 3 mitigation. [ABSTRACT FROM AUTHOR]

• Environmental impacts of conventional and circular crop-poultry system were compared. • Mitigation measures for housing, manure processing and application were tested. • Reactive nitrogen losses and greenhouse gas emissions were assessed in both systems. • Losses were reduced by 35–52% with an economic benefit of 21% in the circular system. • These benefits can drive the transformation to more sustainable production. There is a global need to improve the environmental performances and circularity of livestock production systems. This relates also to poultry production systems in China, however, the benefits of optimized, more circular systems have not been quantified. Here, we applied a substance flow analysis to estimate the reactive nitrogen (Nr) losses and greenhouse gas (GHG) emissions from housing, manure processing and manure application to cropland in a conventional decoupled and an optimized coupled crop-poultry system. We hypothesized that an optimized coupled system has lower Nr losses and GHGs emissions, and a higher economic return for farmers. We used data from experimental measurements, a farm survey, literature and local market prices to estimate the farm performance for both systems. In the conventional system the manure was only partly (58%) utilized and the remaining 42% was wasted and discharged into the environment. In the optimized system a series of emission mitigation measures was adopted, including low-protein feeding, manure composting with additives and a partial replacement of synthetic fertilizers by manure. The optimized system produced 24% more products per 100 units of N input, leading to a whole-system nitrogen use efficiency (NUE) increase from 33% to 50%. The Nr losses per unit of product-N decreased by 55%, whereas the GHG emissions (N 2 O and CH 4) decreased by 35%. Moreover, the net economic benefit increased by 21%. Evidently, the optimized and more circular system had significant economic and environmental benefits compared to the conventional one. These benefits will be drivers for the transformation to more sustainable production systems, but governmental policy incentives will be needed to remove current cultural and institutional barriers. [Display omitted] [ABSTRACT FROM AUTHOR]

Reactive nitrogen (Nr) plays a key role in the atmospheric environment and its deposition has induced large negative impacts on ecosystem health and services. Five-year continuous in-situ monitoring of N deposition, including wet (total nitrogen ( W TN), total dissolved nitrogen ( W TDN), dissolved organic nitrogen ( W DON), ammonium nitrogen ( W AN) and nitrate nitrogen ( W NN)) and dry ( D NH 3 , D HNO 3 , D pNH 4 + , D pNO 3 − and D NO 2 ) deposition, had been conducted since August 2008 to December 2013 (wet) and May 2011 to December 2013 (dry) in Yan-ting, China, a typical agricultural area in the central Sichuan Basin. Mean annual total N deposition from 2011 to 2013 was 30.8 kg N ha −1 yr −1 , and speculated that of 2009 and 2010 was averaged 28.2 kg N ha −1 yr −1 , respectively. Wet and dry N deposition accounted for 76.3% and 23.7% of annual N deposition, respectively. Reduced N ( W AN, D NH 3 and D pNH 4 + ) was 1.7 times of oxidized N ( W NN, D HNO 3 , D NO 2 and D pNO 3 − ) which accounted for 50.9% and 30.3% of TN, respectively. Maximum loadings of all N forms of wet deposition, gaseous NH 3 , HNO 3 and particulate NH 4 + in dry deposition occurred in summer and minimum loadings in winter. Whether monthly, seasonal or annual averaged, dissolved N accounted for more than 70% of the total. N deposition in the central Sichuan Basin increased during the sampling period, especially that of ammonium compounds, and has become a serious threat to local aquatic ecosystems, the surrounding forest and other natural or semi-natural ecosystems in the upper reaches of the Yangtze River. [ABSTRACT FROM AUTHOR]

Air pollution is one of the most serious environmental problems in China due to its rapid economic development alongside a very large consumption of fossil fuel, particularly in the North China Plain (NCP). During the period 2011-2014, we integrated active and passive sampling methods to perform continuous measurements of NH, HNO, NO, and PM at two urban, one suburban, and two rural sites in the NCP. The annual average concentrations of NH, NO, and HNO across the five sites were in the ranges 8.5-23.0, 22.2-50.5, and 5.5-9.7 μg m, respectively, showing no significant spatial differences for NH and HNO but significantly higher NO concentration at the urban sites. At each site, annual average concentrations of NH and NO showed increasing and decreasing trends, respectively, while there was no obvious trend in annual HNO concentrations. Daily PM concentrations ranged from 11.8 to 621.0 μg m at the urban site, from 19.8 to 692.9 μg m at the suburban site, and from 23.9 to 754.5 μg m at the two rural sites, with more than 70 % of sampling days exceeding 75 μg m. Concentrations of water-soluble ions in PM ranked differently between the non-rural and rural sites. The three dominant ions were NH, NO, and SO and mainly existed as (NH)SO, NHHSO, and NHNO, and their concentrations averaged 48.6 ± 44.9, 41.2 ± 40.8, and 49.6 ± 35.9 μg m at the urban, suburban, and rural sites, respectively. Ion balance calculations indicated that PM was neutral at the non-rural sites but acidic at the rural sites. Seasonal variations of the gases and aerosols exhibited different patterns, depending on source emission strength and meteorological conditions. Our results suggest that a feasible pathway to control PM pollution in the NCP should target ammonia and acid gases together. [ABSTRACT FROM AUTHOR]

Ground-level ozone (O 3 ) pollution has become one of the top environmental issues in China, especially in those economically vibrant and densely populated regions. In this paper, we reviewed studies on the O 3 concentration observation and O 3 effects on food crops throughout China. Data from 118 O 3 monitoring sites reported in the literature show that the variability of O 3 concentration is a function of geographic location. The impacts of O 3 on food crops (wheat and rice) were studied at five sites, equipped with Open Top Chamber or O 3 -FACE (free-air O 3 concentration enrichment) system. Based on exposure concentration and stomatal O 3 flux–response relationships obtained from the O 3 -FACE experimental results in China, we found that throughout China current and future O 3 levels induce wheat yield loss by 6.4–14.9% and 14.8–23.0% respectively. Some policies to reduce ozone pollution and impacts are suggested. [ABSTRACT FROM AUTHOR]

Species composition and productivity are influenced by water and N availability in semi-arid grasslands. To assess the effects of increased N deposition and water supply on plant species composition and productivity, two field experiments with four N addition treatments, and three N and water combination treatments were conducted in alpine grassland in the mid Tianshan mountains, northwest China. When considering N addition alone, aboveground biomass (AGB) of forbs (F) responded less to N addition than AGB of grasses (G). G increased as an effect of N combined with water addition but F did not show such an effect, reflecting a stronger response of grasses to the interaction of water availability and N than forbs. Under all treatments, N allocation to the aboveground tissue did not change for either forbs or grasses. N deposition and water addition did not alter species richness in the present study. These results suggest that N addition generally promoted AGB but had little effect on species richness in wet years. Snowfall in winter combined with rainfall in the early growing season likely plays a critical role in regulating plant growth of the subsequent year in the alpine grassland. [ABSTRACT FROM AUTHOR]

China is experiencing intense air pollution caused in large part by anthropogenic emissions of reactive nitrogen. These emissions result in the deposition of atmospheric nitrogen (N) in terrestrial and aquatic ecosystems, with implications for human and ecosystem health, greenhouse gas balances and biological diversity. However, information on the magnitude and environmental impact of N deposition in China is limited. Here we use nationwide data sets on bulk N deposition, plant foliar N and crop N uptake (from long-term unfertilized soils) to evaluate N deposition dynamics and their effect on ecosystems across China between 1980 and 2010. We find that the average annual bulk deposition of N increased by approximately 8 kilograms of nitrogen per hectare (P < 0.001) between the 1980s (13.2 kilograms of nitrogen per hectare) and the 2000s (21.1 kilograms of nitrogen per hectare). Nitrogen deposition rates in the industrialized and agriculturally intensified regions of China are as high as the peak levels of deposition in northwestern Europe in the 1980s, before the introduction of mitigation measures. Nitrogen from ammonium (NH4+) is the dominant form of N in bulk deposition, but the rate of increase is largest for deposition of N from nitrate (NO3−), in agreement with decreased ratios of NH3 to NOx emissions since 1980. We also find that the impact of N deposition on Chinese ecosystems includes significantly increased plant foliar N concentrations in natural and semi-natural (that is, non-agricultural) ecosystems and increased crop N uptake from long-term-unfertilized croplands. China and other economies are facing a continuing challenge to reduce emissions of reactive nitrogen, N deposition and their negative effects on human health and the environment. [ABSTRACT FROM AUTHOR]

Nitrogen (N) deposition is an important component in the global N cycle that has induced large impacts on the health and services of terrestrial and aquatic ecosystems worldwide. Anthropogenic reactive N (Nr) emissions to the atmosphere have increased dramatically in China due to rapid agricultural, industrial and urban development. Therefore increasing N deposition in China and its ecological impacts are of great concern since the 1980s. This paper synthesizes the data from various published papers to assess the status of the anthropogenic Nr emissions and N deposition as well as their impacts on different ecosystems, including empirical critical loads for different ecosystems. Research challenges and policy implications on atmospheric N pollution and deposition are also discussed. China urgently needs to establish national networks for N deposition monitoring and cross-site N addition experiments in grasslands, forests and aquatic ecosystems. Critical loads and modeling tools will be further used in Nr regulation. [Copyright &y& Elsevier]

Abstract: Atmospheric ammonia (NH3) and particulate ammonium (NH4 +) were measured using passive samplers and particulate samplers at four rural and two suburban sites in the North China Plain (NCP) from August 2006 to September 2009. The annual mean concentrations of NH3 and NH4 + in PM10 across the sites were 15.6 and 12.4 μg m−3, respectively. Higher concentrations of NH3 and NH4 + were found at the rural sites compared with the suburban sites. NH3 concentrations were highest in summer and lowest in winter, showing positive correlations with N fertilizer application rates and temperature in each season. Particulate NH4 + showed significant positive correlations with particulate SO4 2− and NO3 − at the six sites. The annual mean concentrations of secondary inorganic particles (sum of NH4 +, SO4 2− and NO3 −) accounted for 26.1–41.3% of the PM10 concentration across all sites. The formation of inorganic NH4 + particles was limited mainly by the availability of H2SO4 and HNO3 and partly by NH3. The total NHx deposition in the NCP averaged 43.5 kg N ha−1 yr−1, accounting for 84.1% of the mean NH3 emission intensity. The serious particulate NH4 + pollution and high NHx deposition suggest the urgency of reducing NH3 emission from agricultural sources in the NCP. [Copyright &y& Elsevier]

Accurately determining methane emission factors of dairy herd in China is imperative because of China’s large population of dairy cattle. An inverse dispersion technique in conjunction with open-path lasers was used to quantify methane emissions from a dairy feedlot during the fall and winter seasons in 2009–2010. The methane emissions had a significant diurnal pattern during both periods with three emission peaks corresponding to the feeding schedule. A 10% greater emission rate in the fall season was obtained most likely by the higher methane emission from manure during that period. An annual methane emission rate of 109 ± 6.7 kg CH4 yr−1 characterized with a methane emission intensity of 32.3 ± 1.59 L CH4 L−1 of milk and a methane conversion factor (Y m) of 7.3 ± 0.38% for mature cattle was obtained, indicating the high methane emission intensity and low milk productivity in Northern China. [Copyright &y& Elsevier]

Many Chinese croplands are suffering from soil acidification, defined as a decrease in soil acid neutralizing capacity (ANC), due to over-application of nitrogen (N) fertilizer and removal of base cations (BCs) in crop harvest. The contribution of fertilization and harvesting on soil acidification rates for different cropping systems is, however, seldom quantified under field conditions. Here, field experiments were conducted on a moderately acid silty clay soil in southwest China to quantify proton (H+) production rates under three fertilization management regimes, including control (non-N), optimized fertilization and farmers' practices (i.e. over fertilization), by measuring the inputs and outputs of major element in three cropping systems, i.e. rice-fallow, rice-wheat and maize-wheat. The maize-wheat cropping system had the highest proton production rates (2.3–10.2 kmol c H+ ha−1 yr−1), followed by rice-fallow (3.2–4.6 kmol c H+ ha−1 yr−1) and rice-wheat (2.2–4.5 kmol c H+ ha−1 yr−1) systems. Crop removal, dominated by straw removal, was the main driver of proton production in all three cropping systems, contributing over 50% of the total H+ production. Compared to the control, N fertilizer application enhanced soil acidification rates among three cropping systems, but had no significant effects on H+ production per kg grain in the rice-fallow and rice-wheat systems. The same was true for the maize-wheat system in case of optimized fertilization, but over fertilization increased both soil acidification rate and H+ production per kg grain, while grain yield was comparable to that with optimized fertilization. The change in soil ANC was dominated by accumulation of SO 4 2− (leading to potential soil acidification) that was mainly added to the soil with superphosphate containing high concentrations of both Ca2+ and SO 4 2− sometimes even causing an increase in the base cation pool, despite BC crop removal. The low contribution of N transformation processes to the total H+ production (3–47%) was due to high denitrification in this specific soil. The soil pH and base saturation did not change significantly among the three fertilization management regimes, largely due to the large BCs pools in the soil. Although the common farmers' practice does not strongly increase proton production in rice-fallow and rice-wheat systems, it still implies a waste of N fertilizer as the excess N input is either enhancing straw production or lost to air in this silty clay soil. Hence, optimized fertilization and localized BCs-rich straw return are suggested to reduce costs of N fertilizer without yield losses and mitigate soil acidification in those systems. [Display omitted] • Soil acidification rates were quantified in three cropping systems in China. • Maize-wheat rotations had higher acidification rates than rice-wheat and rice-fallow. • Optimized N fertilization reduced soil acidification rates without yield loss. • Base cation removal by crop harvesting was the main driver of soil acidification. • Low contribution of N cycle to soil acidification was due to high denitrification. [ABSTRACT FROM AUTHOR]

The study of emissions and depositions of atmospheric reactive nitrogen species (N r s) in a region is important to uncover the sources and sinks of atmospheric N r s in the region. In this study, atmospheric total N r s depositions including both wet-only and dry deposition were monitored simultaneously across major land-use types in a 105 km2 catchment called Jinjing River Catchment (JRC) in subtropical central China from 2015 to 2016. Based on activity data and emission factors for the main N r s emission sources, ammonia (NH 3) and nitrogen oxides (NO x) emission inventories for the catchment were also compiled. The estimated total N r s deposition in JRC was 35.9 kg N ha−1 yr−1, with approximately 49.7 % attributed to reduced compounds (NH x), and 40.5 % attributed to oxidized (NO y). The total N r s emission rate in JRC was 80.4 kg N ha−1 yr−1, with 61.5 and 18.9 kg N ha−1 yr−1 from NH 3 and NO x emissions, respectively. Livestock excretion and fertilization were the two main contributing emission sources for NH 3 , while vehicle sources contributed the bulk of NO x emissions. The net atmospheric budgets of N r s in paddy field, forest, and tea field were +3.7, −36.1, and +23.8 kg N ha−1 yr−1, respectively. At the catchment scale, the net atmospheric budget of N r s was +47.7 kg N ha−1 yr−1, with +43.7 kg N ha−1 yr−1 of NH x and +4.0 kg N ha−1 yr−1 of NO y , indicating that the subtropical catchment was net sources of atmospheric N r s. Considering that excessive atmospheric N r emissions and deposition may cause adverse effects on the environment, effects should be conducted to mitigate the N r s emissions from agriculture and transportation, and increasing the area of forest is good for reducing the net positive budget of atmospheric N r s in the subtropical catchments in China. [Display omitted] • Mean atmospheric N r deposition was 36 kg N ha−1 yr−1 in a subtropical catchment in a 2-yr study. • Total N r emissions in catchment were 80 kg N ha−1 yr−1, with 62 kg N ha−1 yr−1 from NH 3 emissions. • The net N r budget showed high emissions due to NH 3 emissions from livestock and fertilization. • Paddy and tea fields were net sources of N r s, while forest was a net strong sink of N r s. Both atmospheric emissions and depositions of Nrs were high, and the net budget showed high emissions in a typical agricultural catchment in subtropical central China. [ABSTRACT FROM AUTHOR]

High ammonia (NH 3) emissions from fertilized soil in China have led to various concerns regarding environmental safety and public health. In response to China's blue skies protection campaign, effective NH 3 reduction measures need to consider both mitigation efficiency and food security. In this context, we conducted a meta-analysis (including 2980 observations from 447 studies) to select effective measures based on absolute (AV) and yield-scaled (YSAV) NH 3 volatilization reduction potential, with the aim of establishing a comprehensive NH 3 mitigation framework covering various crop production sectors, and offering a range of potential solutions. The results showed that manipulating crop density, using an intermittent irrigation regime for paddy field rice, applying N as split applications or partially substituting inorganic fertilizer N with organic N sources could achieve reductions in AV and YSAV reduction of 10–20 %; adopting drip irrigation regimes, adding water surface barrier films to paddy fields, or using double inhibitor (urease and nitrification), slow-release or biofertilizers could achieve 20–40 % mitigation; plastic film mulching, applying fertilizer by irrigation or using controlled-release fertilizers could yield 40–60 % reduction; use of a urease inhibitor, fully substituting fertilizer N with organic N, or applying fertilizer by deep placement could decrease AV and YSAV by over 60 %. In addition, use of soil amendments, applying suitable inorganic N sources, or adopting crop rotation, intercropping or a rice-fish production model all had significant benefits to control AV. The adoption of any particular strategy should consider local accessibility and affordability, direct intervention by local/government authorities and demonstration to encourage the uptake of technologies and practices, particularly in NH 3 pollution hotspot areas. Together, this could ensure food security and environmental sustainability. [Display omitted] • A comprehensive NH 3 mitigation framework for various crop production sectors was established. •Improved field and nutrient management reduces both NH 3 and yield-scaled NH 3 emissions. •Diversified cropping systems provide ecological options of controlling agricultural NH 3 loss. [ABSTRACT FROM AUTHOR]

Nitrogen (N) input from atmospheric deposition is a concern in the North China Plain (NCP). To quantify the magnitude of the problem, the total airborne N deposition to agroecosystems in the NCP was quantified using a manual ITNI (integrated total nitrogen input) system and a long-term experiment (LTE). Total estimated N deposition averaged 83. 3kgNha−1 across the sites Dongbeiwang (DBW) of Beijing, Wuqiao (WQ) and Quzhou (QZ) of Hebei, with atmospheric N input 14kgNha−1 in the period from flowering to maturity, when maize (Zea mays) was the monitoring crop. The 15N-supply level in the ITNI system seemed not to affect the estimation of N deposition significantly. However, the N deposition value was only 48. 6kgNha−1 on average when ryegrass (Lolium multiflorum) was cultivated during the same period of maize (May–September), suggesting that total airborne N input varies with the monitoring crop, largely because of the different surface areas. The total annual N deposition obtained from zero-N plots of LTE at Changping (82. 8kgNha−1) supported the N deposition results from the maize-based ITNI systems. [Copyright &y& Elsevier]

Chinese agriculture represents one of the most intensively managed agroecosystems in the world. Typical nitrogen fertilization rates are more than three times those of the world' s average, resulting in dramatically accelerated nitrogen cycling in China. In this study, we have examined NO and N2O exchange in the upland agricultural systems of Beijing area. Inorganic and organic fertilizer treatments were arranged in order to evaluate their impact on the magnitude and proportion of trace gas emissions. Increasing inorganic fertilization rates showed a highly significant impact upon emissions of both NO and N2O. Organic matter amendment did not have a statistically significant impact on the N-gas fluxes examined here. Overall losses of added nitrogen by NO and N2O emission averaged 1. 24% and 0. 22% respectively over the range of treatments in this study. Results from our field study indicate that compared with other studies done elsewhere, emissions of reactive nitrogen from agricultural systems in Beijing area are not so large as expected before. [ABSTRACT FROM AUTHOR]

The Clean Air Action implemented by the Chinese government in 2013 has greatly improved air quality in the North China Plain (NCP). In this work, we report changes in the chemical components of atmospheric fine particulate matter (PM 2.5) at four NCP sampling sites from 2012/2013 to 2017 to investigate the impacts and drivers of the Clean Air Action on aerosol chemistry, especially for secondary inorganic aerosols (SIA). During the observation period, the concentrations of PM 2.5 and its chemical components (especially SIA, organic carbon (OC), and elemental carbon (EC)) and the frequency of polluted days (daily PM 2.5 concentration ≥ 75 μg m−3) in the NCP, declined significantly at all four sites. Asynchronized reduction in SIA components (large decreases in SO 4 2− with stable or even increased NO 3 − and NH 4 +) was observed in urban Beijing, revealing a shift of the primary form of SIA, which suggested the fractions of NO 3 − increased more rapidly than SO 4 2− during PM 2.5 pollution episodes, especially in 2016 and 2017. In addition, unexpected increases in the sulfur oxidation ratio (SOR) and the nitrogen oxidation ratio (NOR) were observed among sites and across years in the substantially decreased PM 2.5 levels. They were largely determined by secondary aerosol precursors (i.e. decreased SO 2 and NO 2), photochemical oxidants (e.g. increased O 3), temperature, and relative humidity via gas-phase and heterogeneous reactions. Our results not only highlight the effectiveness of the Action Plan for improving air quality in the NCP, but also suggest an increasing importance of SIA in determining PM 2.5 concentration and composition. [Display omitted] • PM 2.5 and its chemical components were reduced in North China Plain during 2012–2017. • Reduced air pollutant emissions contributed more to PM 2.5 decline than meteorology. • NO 3 − became increasingly important in the formation of secondary inorganic aerosols. • Both sulfur oxidation ratio and nitrogen oxidation ratio increased unexpectedly. [ABSTRACT FROM AUTHOR]