Average NO2 Research Articles

Short-term exposure to outdoor nitrogen dioxide and respiratory mortality, with high-risk populations: a nationwide time-stratified case-crossover study

Numerous existing studies reported the negative impacts of outdoor nitrogen dioxide (NO2) on respiratory mortality. However, the evidence of related high-risk populations was considerably limited, especially associated with ages, causes of death, and district-level characteristics. In addition, most earlier studies were based on monitored areas, thus previous risk estimates of NO2 could be biased to provide nationwide risk estimates and high-risk populations. Therefore, this study performed a nationwide time-stratified case-crossover study to evaluate the association between short-term ambient NO2 and respiratory mortality in South Korea (2015–2019). A machine learning-ensemble daily NO2 prediction model was used to cover unmonitored areas. To examine high-risk populations, we assessed NO2 risk estimates by age group, sex, cause of mortality, and district-level characteristics. In the total population, NO2 was weakly associated with increased mortality risk due to respiratory disease (OR [odds ratio]: 1.011, 95% CI [confidence interval]: 0.995–1.027), and the association became evident only in individuals aged 80 y or older (1.022, 1.000–1.044), especially related to pneumonia. Further, in people aged 60–69 years, NO2 was marginally associated with mortality for chronic lower respiratory diseases. Lower district-level socioeconomic status and medical services were marginally related to higher respiratory mortality risks related to NO2. The excess respiratory mortality fractions and YLL (year of life lost) attributable to NO2 were 4.13% and 93,851.63 years, and around 70% of the excess deaths were due to noncompliance with the World Health Organization air quality guidelines (daily average NO2 > 25 µg/m3). This study provides evidence for high-risk populations and the appropriateness of target-specific action plans against NO2. In addition, based on the excess death estimates, we suggest stricter NO2 standards are required.

Chemical characterization and source identification of PM2.5 in the Huaxi urban area of Guiyang

In 2020, 123 PM2.5 samples were collected across different seasons in Huaxi District, Guiyang. The primary chemical components of PM2.5, including water-soluble ions (WSIIs), metallic elements, organic carbon (OC), and elemental carbon (EC), were analyzed. During the sampling period, the average PM2.5 concentration was 39.7 ± 22.3 µg/m2. Chemical mass closure (CMC) was used to reconstruct PM2.5 mass, yielding a reconstructed concentration of 29.1 ± 16.5 µg/m2. The major components were organic matter (OM), sulfate + nitrate + ammonium (SNA), and mineral dust (MD), with mean concentrations of 12.2 ± 6.3 µg/m2, 8.2 ± 4.0 µg/m2, and 6.3 ± 4.6 µg/m2, respectively. From clean days (CD) to lightly-moderately polluted days (LMPD), nitrate oxidation ratio (NOR) increased from 0.09 to 0.16, while sulfate oxidation ratio (SOR) and OC/EC ratio rose by 21.7% and 13.5%, indicating stronger secondary reactions on polluted days. The study also examined changes in chemical components under different atmospheric oxidizing and humidity conditions, revealing that sulfate and nitrate concentrations increased with relative humidity (RH) between 60 and 80%, while other components, especially MD, showed a declining trend due to hygroscopic growth and subsequent gravitational settling and precipitation. The average NO3−/SO42− ratio was 0.67, indicating that fixed sources such as industrial and coal emissions were the main contributors to PM2.5. This study provides insights into the chemical composition, pollution processes, and formation mechanisms of PM2.5, which are crucial for developing effective air pollution control strategies. Furthermore, source apportionment was conducted with the positive matrix factorization (PMF) model. The Coal combustion, secondary, traffic, Industrial and dust source contributions to the PM2.5 mass were approximately 30.5%, 20.0%, 18.3%,16.7% and 14.5%, respectively.

Insights into the influence of organic and salinity on the two-stage partial nitritation/anammox process in treating food waste digestate

ABSTRACT Food waste digestate (FWD), which contains significant levels of ammonium, organic matter, and salinity, can interfere with treatment performance of the anammox process. In this study, a two-stage partial nitritation/anammox (PN/A) process was established to investigate nitrogen removal and microbial response in treating FWD at a nitrogen loading rate (NLR) of 0.27 ± 0.02 gN/L/d. High concentrations of free ammonia (58 mg/L) and free nitrous acid (0.3 mg/L) facilitated the initiation of the partial nitritation (PN) process, achieving an average NO2 −/NH4 + ratio of 1.28 ± 0.08. For the anammox process, a nitrogen removal rate (NRR) of 0.72 ± 0.13 gN/L/d was achieved. Free ammonia (NH3) stripping, Anammox pathway, and denitrification pathway contributed 4.1 ± 0.3%, 5.1 ± 0.2%, and 84.0 ± 1.5% of the total nitrogen removal, respectively. Nitrosomonas, a salt-tolerant ammonia-oxidizing bacteria (AOB), was enriched to 1.0%, while Nitrospira, a nitrite-oxidizing bacteria (NOB), was effectively suppressed to 0.003%. The salt-tolerant anammox genera unclassified_f__Brocadiaceae (13.9%) and Candidatus_Kuenenia (4.8%) dominated the nitrogen removal pathway. The high enrichment of unclassified_f__Brocadiaceae ensured stable operation of the anammox process at 0.62 ± 0.11% salinity, even with a high initial FA inhibition concentration of 40 mg/L. Additionally, norank_f_A4b (1.34%) and norank_f_norank_o_SBR1031 (52.1%) facilitated the hydrolysis of refractory organic matter. Denitrifying bacteria, including Hyphomicrobium, Truepera, and unclassified_c__Alphaproteobacteria, played significant roles in nitrate removal, with a CODconsumed/NO3 − removed ratio of 2.7 ± 0.2. This study highlights the application of a two-stage PN/A process for rapid startup and effective nitrogen removal from FWD.

Associations of long-term nitrogen dioxide exposure with a wide spectrum of diseases: a prospective cohort study of 0·5 million Chinese adults

Little evidence is available on the long-term health effects of nitrogen dioxide (NO2) in low-income and middle-income populations. We investigated the associations of long-term NO2 exposure with the incidence of a wide spectrum of disease outcomes, based on data from the China Kadoorie Biobank. This prospective cohort study involved 512 724 Chinese adults aged 30-79 years recruited from ten areas of China during 2004-08. Time-varying Cox regression models yielded adjusted hazard ratios (HRs) for the associations of long-term NO2 exposure with aggregated disease incidence endpoints classified by 14 ICD-10 chapters, and incidences of 12 specific diseases selected from three key ICD-10 chapters (cardiovascular, respiratory, and musculoskeletal diseases) found to be robustly associated with NO2 in the analyses of aggregated endpoints. All models were stratified by age-at-risk (in 1-year scale), study area, and sex, and were adjusted for education, household income, smoking status, alcohol intake, cooking fuel type, heating fuel type, self-reported health status, BMI, physical activity level, temperature, and relative humidity. The analysis of 512 709 participants (mean baseline age 52·0 years [SD 10·7]; 59·0% female and 41·0% male) included approximately 6·5 million person-years of follow-up. Between 5285 and 144 852 incident events were recorded for each of the 14 aggregated endpoints. Each 10 μg/m3 higher annual average NO2 exposure was associated with higher risks of chapter-specific endpoints, especially cardiovascular (n=144 852; HR 1·04 [95% CI 1·02-1·05]), respiratory (n=73 232; 1·03 [1·01-1·05]), musculoskeletal (n=54 409; 1·11 [1·09-1·14]), and mental and behavioural (n=5361; 1·12 [1·05-1·21]) disorders. Further in-depth analyses on specific diseases found significant positive supra-linear associations with hypertensive disease (1·08 [1·05-1·11]), lower respiratory tract infection (1·03 [1·01-1·06]), arthrosis (1·15 [1·09-1·21]), intervertebral disc disorders (1·13 [1·09-1·17]), and spondylopathies (1·05 [1·01-1·10]), and linear associations with ischaemic heart disease (1·03 [1·00-1·05]), ischaemic stroke (1·08 [1·06-1·11]), and asthma (1·15 [1·04-1·27]), whereas intracerebral haemorrhage (1·00 [0·95-1·06]), other cerebrovascular disease (0·98 [0·96-1·01]), acute upper respiratory infection (1·03 [0·96-1·09]), and chronic lower respiratory disease (0·98 [0·95-1·02]) showed no significant association. NO2 exposure showed robust null association with external causes (n=32 907; 0·98 [0·95-1·02]) as a negative control. In China, long-term NO2 exposure was associated with a range of diseases, particularly cardiovascular, respiratory, and musculoskeletal diseases. These associations underscore the pressing need to implement the recently tightened WHO air quality guidelines. Wellcome Trust, UK Medical Research Council, Cancer Research UK, British Heart Foundation, National Natural Science Foundation of China, National Key Research and Development Program of China, Sino-British Fellowship Trust, and Kadoorie Charitable Foundation.

Exploring fine-aerosol episodes in urban Seoul during the cold season of the 2021 SIJAQ campaign: Measurement evidences of heterogeneous reactions on black carbon particles

Significant PM2.5 pollution has been prevalent on a regional scale in East Asia including a megacity Seoul in South Korea. Here, we explore fine-aerosol episodes occurred in Seoul during the Satellite Integrated Joint monitoring of Air Quality (SIJAQ) campaign from October to November of the 2021, focusing on experimental evidences of heterogeneous reactions to form secondary aerosol under a highly oxidized atmospheric condition.At this urban site in Seoul, vehicle exhaust was the clear source of fresh emissions, leading to a high level of NO and small refractory black carbon (rBC) particles (mass median diameter of 162 nm ± 16 nm) in the morning time. The hourly mass concentration of PM2.5 ranged from 5.3 μg m−3 to 146.1 μg m−3, averaging at 24.5 ± 22.2 μg m−3. During the campaign, the most intense episode, EP3 (November 18–21), recorded an average PM2.5 concentration of 72.5 ± 38.2 μg m−3, peaking at 146.1 μg m−3, was characterized by relatively higher temperature (∼12 °C) and relative humidity (67 %) on average thoroughly governed by continental migratory high and westerly winds. While the average NO3− concentration was 27.7 μg m−3, four times the whole campaign's average, EP3 was highlighted by a high morning NO2/NOx ratio and significantly elevated daytime and nighttime Ox (O3+NO2) concentrations compared to non-episode days. Throughout the entire campaign, NOz surrogate (NO2(CL)-NO2(T)), Ox, and Fmoderate + thick (the combined number fractions of moderately and thickly coated-rBC particles) tended to increase with the PM2.5 concentration. During the daytime, as PM2.5 increased, Fmoderate + thick showed a monotonic increase, accompanied by RH rising from 54 ± 16% to 63 ± 11%. In contrast, at nighttime of humid condition with RH often exceeding 70% the enhancement of Fmoderate + thick was more sensitive to condensable gas levels than RH. Given that high levels of PM2.5 (>60 μg m−3) were observed only during EP3, enhanced levels of NOz surrogate, Ox, Fmoderate + thick, and RH were evident characteristics of EP3. Such chemical and meteorological conditions suggest that the chemically enhanced oxidation state was evident during EP3, which promoted the formation of secondary aerosols on primary particles including rBC, especially under conditions of elevated RH. Considering the recent trend of increasing number of vehicles and rising atmospheric O3 concentrations in East Asia, future studies should be well designed to investigate the detailed mechanisms involved in heterogeneous reactions that lead to the formation of secondary aerosols.

Estimation of Near-surface NO2 Concentration in Guangdong Province Based on Catboost Model

Nitrogen oxide （NOx） is an important air pollutant in the atmosphere, and nitrogen dioxide （NO2） is one of its main components. The monitoring and estimation of NO2 concentration is very important for environmental protection and public health. The near-real-time nitrogen dioxide concentration data （NRTI NO2）, ERA5 meteorological reanalysis data, and DEM data provided by Sentinel-5P atmospheric pollution monitoring satellite were used as estimation variables to estimate the near-surface NO2 concentration in Guangdong Province based on the Catboost model. The results showed that： ① The Catboost model estimated the near-surface NO2 concentration with the highest accuracy, with the coefficient of determination （R2）, root mean square error （RMSE）, and mean absolute error （MAE） of the model fit reaching 0.91, 4.89 μg·m-3, and 3.45 μg·m-3 and the cross-validated R2, RMSE, and MAE reaching 0.90, 4.91 μg·m-3, and 3.43 μg·m-3, with good stability on the monthly and quarterly scales. ② The monthly average NO2 concentration near the surface of Guangdong Province showed a U-shaped trend, with the highest value of 43.8 μg·m-3 in January and the lowest value of 14.37 μg·m-3 in July. The seasonal distribution of the near-surface NO2 concentration was characterized by "high during winter and low during summer and transitional during spring and autumn," and the NO2 concentration in each season was in the following order： winter （27.53 μg·m-3） > spring （20.77 μg·m-3） > autumn （18.77 μg·m-3） > summer （14.85 μg·m-3）. ③ From a spatial distribution perspective, areas with high near-surface NO2 values in Guangdong Province were mainly located in rapidly developing and densely populated areas, while areas with low values were mainly distributed in areas focusing on port economy, agriculture, and new energy sources.

A room-temperature NO2 gas sensor based on Zn2+ doped Cu2O/CuO composites with ultra-high response

Metal oxide semiconductors (MOS) have attracted increasing interest in gas sensors recently due to their exceptional design flexibility and superior gas sensing capabilities. However, the high operating temperatures and reliance on light activation in MOS-based gas sensors limit their potential applications. In this work, the Zn2+ doped Cu2O/CuO composites were successfully fabricated by one-step hydrothermal method for the detection of NO2 gas at room temperature. The experimental results show that the optimal Zn-Cu2O/CuO composite presents responses that are 2.9, 3.4, 3.1 times higher than those of the pure Cu2O/CuO composite to 10, 5 and 1 ppm NO2. Additionally, the response and recovery times are shortened by factors of 3.1 and 1.4, respectively. Notably, the detection limit of the Zn-Cu2O/CuO composite is 2 ppb at room temperature, significantly below China's annual average NO2 concentration limit of ∼18 ppm. Furthermore, the Zn-Cu2O/CuO based sensor demonstrates the great selectivity, repeatability and long-term stability for NO2 detection. The gas sensitivity enhancement mechanism is thoroughly discussed. This result provides a new approach for the effective detection of ppb-level NO2 by CuO-based gas sensing materials at room temperature.

Long-Term exposure to NO2 and Stroke Mortality in Portugal: an ecological study from 2001 to 2021

Abstract Background Air pollution is an important contributing factor for many pathologies, including stroke. Nitrogen dioxide (NO2), an air pollutant, has been associated in multiple studies with strokes’ mortality. Aim This study aims, for the first time, to estimate the number of deaths by stroke due to long-term, ambient exposure to nitrogen dioxide in Portugal for the years 2001-2021. Methods An ecological study was considered, including data for NO2 outdoor concentration from Portugal. Mortality data by stroke was obtained divided in 5-year groups. It was also obtained life expectancy for each year to calculate the years of life lost (YLL). The hazard ratio (HR) was obtained from literature (1.009, CI 1.003-1.016). The population attributable fraction (PAF) of YLL by stroke due to ambient NO2 long-term exposure was calculated. Results The annual average NO2 concentration in Portugal decreased from its peak in 2001 of 29.4 to 12.2 µg/m3 in 2021. The YLL by stroke decreased from an estimated 57452 to 31204 from 2001 to 2021. The PAF of YLL by stroke due to ambient NO2 long-term exposure reached its peak in 2001, when an estimated 5.2% of all the YLL by stroke, corresponding to 3029 YLL, were due to NO2 exposure and a bottom in 2021, when 2.2%, corresponding to 682 YLL, where due NO2 exposure. Conclusions The policies and legislation implemented to curb down NO2 seem to have had an effect in Portugal. A reduction in NO2 emissions was achieved, having a significant impact on YLL by stroke in Portugal, suggesting that curbing the NO2 emissions down had a positive effect on mortality by stroke in Portugal. To further enhance our knowledge on the real impacts of NO2, further studies must be conducted to estimate the morbidity associated with NO2 on stroke as well as in other diseases. Key messages • Pollution by nitrogen dioxide decreased significantly from 2001 to 2021. • Around 20000 years of life were lost just in Portugal due to nitrogen dioxide between 2001 and 2021.

Unveiling synergistic enhancement mechanism of nitrogen removal in surface flow constructed wetlands: Utilizing iron scraps and elemental sulfur as integrated electron donors

Lacking electron donors generally causes poor denitrification performance in constructed wetlands (CWs). In this study, iron scraps (ISs) and elemental sulfur (S0) were employed as electron donors in different surface flow constructed wetlands (SFCWs): control (C-SF), ISs added (Fe-SF), S0 added (S-SF), and ISs and S0 combined (Fe + S-SF) to investigate the performance and mechanism of nitrogen (N) removal through continuous flow and batch experiments. The impact of hydraulic retention times (HRTs) and temperatures on N removal was explored. The combined use of ISs and S0 significantly improved nitrate (NO3− -N) removal in Fe + S-SF compared to the other SFCWs. During the 3-d HRT at 25 °C, the average NO3− -N removal efficiency in Fe + S-SF reached the highest value of 71.66 ± 12.54%, reducing NO3− -N concentrations from 12.03 mg/L to 3.47 mg/L. The results of the batch experiments revealed an N removal pattern that aligned with the findings of the continuous flow experiment. The microbial community analysis revealed a selective enrichment of key functional genera (e.g., Ferritrophicum and Dechloromonas), contributing to enhanced N removal in Fe + S-SF. These findings suggest that the synergistic use of ISs and S0 can achieve better denitrification efficiency and potentially be utilized for enhanced N removal from low C/N wastewater.

A preliminary report of integrating sheep farming in combination with adopting biogas technology in organic rice farming systems in upland areas in Indonesia

This study aims to understand the preliminary results of integrating sheep farming in combination with adopting biogas technology in organic rice farming (ORF) systems in upland areas. The research was conducted in upland areas in Grabag Subdistrict Magelang Regency, Central Java Province (UPL1) and Kertasari Subdistrict, Tasikmalaya Regency, West Java Province (UPL2), Indonesia. At each upland area, a demo plot with a 17 m3 digester has been established, and 120 sheep were introduced. A combination of sheep and beef cattle manure was used as a biogas substrate. The soil sample of one and three-year conversion of ORF was collected, and macro and micro minerals were analyzed. The biogas quality was analyzed, including dry matter (DM), nitrogen (N), carbon (C) and nitrogen-ammonia (N-NH3). The greenhouse (GHG) emissions, including methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O), were measured. The results indicated that C-organic content at three-year conversions of ORF in UPL1 was much lower (P<0.05) than the one-year conversion. The average CH4, CO2, and N2O contents in UPL1 were 661, 477.3, and 0.16 mg/m2/day, respectively. The average CH4, CO2, and N2O contents in UPL2 were 3328, 3038 and 2.42 mg/m2/day, respectively. In UPL1, the proportion of CH4 was 52.5 %, CO2 was 47.4 %, and N2O was 0.01 % while the proportion of CH4 was 57.9 %, CO2 was 42.0 %, and N2O was 0.01 % in UPL2. To conclude, integrating sheep farming in combination with adopting biogas technology in the ORF system improves manure management and provides organic fertilizer, which subsequently reduces the use of artificial fertilizer and avoids GHG emissions.v

Impact of net zero policy scenarios on air pollution inequalities in England and Wales

BackgroundThe UK is committed to achieve net zero greenhouse gas emissions by 2050. The suite of policies needed to reach net zero will lead to improvements in air quality and, consequently, could lessen air pollution inequalities. We assessed air pollution inequalities across different sociodemographic groups in England and Wales and explored how these might be differentially impacted by future air pollution projections in 2030 and 2040 under net zero policies. MethodsWe employed a geodemographic classification approach to categorise neighbourhoods into five distinct clusters based on 2021 UK Census sociodemographic variables. We modelled fine particulate matter (PM2.5) and nitrogen dioxide (NO2) concentrations for the year 2019, and predicted concentrations in 2030 and 2040. We compared a business-as-usual (BAU) scenario and two policy pathways to achieve net zero currently considered by the UK government. We aggregated air pollution concentrations to the neighbourhood level and assessed differential neighbourhood-level concentrations across the geodemographic groups using descriptive statistics and box plots. ResultsThe Urban Central Professionals group experienced 14 µg/m3 higher average NO2 concentrations compared with the Rural Elderly group in 2019. Despite substantial improvements to air quality in 2030 and 2040 of up to 6.3 µg/m3 for NO2 based on BAU, and further reductions of up to 2.4 µg/m3 NO2 under net zero policies, the overall pattern of inequality persists, but is predicted to be less pronounced. ConclusionsOur findings demonstrate the effectiveness of targeted policies and innovations in reducing both air quality and greenhouse gas emissions and in bridging the environmental inequality gap. Our findings are essential to develop targeted communication campaigns to secure acceptance and willingness across the sociodemographic spectrum to support the significant behavioural changes needed to achieve net zero, by highlighting the wider co-benefits to the environment and health of such policies.

Relationship Between Greenhouse Gases Emissions with Some Meteorological Variables Over Baghdad City

When infrared radiation from the earth is emitted and back to it, the gases known as greenhouse gases can absorb this entire thermal energy, which is what causes global warming. In addition to other gases including those present on the surface of the ozone layer, nitrous oxides, and fluorinated gases, water vapour is one of the most significant greenhouse gases, albeit its impact is less. Although it is a straightforward type of atmospheric gas, greenhouse gases have a huge impact on the planet’s energy system and have been implicated in significant global climate change. The methods used in the study depend on the daily and monthly average CH4, H2O, N2O, CO2 and temperature (T) and Dewpoint temperature (Td) and relative humidity (RH) taken from the European Mediterranean Weather Forecast (ECMWF) during the year (2021) for the Baghdad region. As a result, in the Statistical analysis of air pollutants, carbon dioxide gas represents the highest correlation with heat, and this leads to high global warming, followed by ozone, methane, and water vapour.

Seasonal patterns of influenza incidence and the influence of meteorological and air pollution factors in Thailand during 2009–2019

Influenza, an acute respiratory illness, remains a significant public health challenge, contributing substantially to morbidity and mortality worldwide. Its seasonal prevalence exhibits diversity across regions with distinct climates. This study aimed to explore the seasonal patterns of influenza and their correlation with meteorological and air pollution factors across six regions of Thailand. We conducted an analysis of monthly average temperature, relative humidity, precipitation, PM10, NO2, O3 concentrations, and influenza incidence data from 2009 to 2019 using wavelet analysis. Our findings reveal inconsistent biannual influenza prevalence patterns throughout the study period. The biannual pattern emerged during 2010–2012 across all regions but disappeared during 2013–2016. However, post-2016, the biannual cycles resurfaced, with peaks occurring during the rainy and winter seasons in most regions, except for the southern region. Wavelet coherence reveals that relative humidity can be the main influencing factor for influenza incidence over a one-year period in the northern, northeastern, central, Bangkok-metropolitan, and eastern regions, not in the southern region during 2010–2012 and 2016–2018. Similarly, precipitation can drive the influenza incidence at the same period for the northeastern, central, Bangkok-metropolitan, and eastern regions. PM10 concentration can influence influenza incidence over a half-year period in the northeastern, central, Bangkok-metropolitan, and eastern regions of Thailand during certain years. These results enhance our understanding of the temporal dynamics of influenza seasonality influenced by weather conditions and air pollution over the past 11 years. Such knowledge is invaluable for resource allocation in clinical settings and informing public health strategies, particularly in navigating Thailand's climatic complexities.

Simulating air pollution at the province level: A case of Ba Ria – Vung Tau province, Vietnam

Abstract This study aimed to simulate air pollution in Ba Ria - Vung Tau province (BR-VT), a significant transportation hub in Vietnam and Southeast Asia. The FVM-TAPOM model system was employed to create a spatial distribution map of air pollution concentration including PM2.5, PM10, NO2, SO2, and CO. The model had sufficient capability for simulating air pollutant distribution (R2>0.6). For PM2.5, the average simulated 1-hour PM2.5 concentration is highest during the dry and rainy seasons, reaching 68 μg/m3 and 46 μg/m3, respectively. For PM10, the average 1-hour simulated PM10 dust concentration is highest during the dry and rainy seasons, reaching 90 μg/m3 and 62 μg/m3, respectively. For NO2, the average 1-hour simulated NO2 concentration is highest during the dry and rainy seasons, reaching 56 (μg/m3) and 46 μg/m3, respectively, which is lower than the permissible threshold of QCVN 05:2023/BTNMT (1-hour average 200 μg/m3). For SO2, the average 1-hour simulated SO2 concentration is highest during the dry and rainy seasons, reaching 140 μg/m3 and 88 μg/m3, respectively, which is lower than the permissible threshold of QCVN 05:2023/BTNMT (1-hour average 350 μg/m3). For CO, the average 1-hour simulated CO concentration is highest during the dry and rainy seasons, reaching 2.950 μg/m3 and 2.280 μg/m3, respectively, which is lower than the permissible threshold of QCVN 05:2023/BTNMT (1-hour average 30.000 μg/m3).

National, satellite-based land-use regression models for estimating long-term annual NO2 exposure across India

In India, scarcity of ground-based measurements of nitrogen dioxide (NO2) is a major challenge for estimating long-term exposure and associated health impacts. This study aimed to develop and validate a national-scale annual NO2 exposure model for India for 2019 and determine if model cross-validation predictive ability was improved by including non-continuous (manual) measurements along with reference-grade, continuous measurements.We used a supervised forward-addition linear regression method to fit land use regression (LUR) models developed with up to 804 Central Pollution Control Board ground monitoring stations (n = 157 continuous, n = 647 manual) and 209 spatial predictor variables, including satellite-based tropospheric NO2 columns. Two models were developed: one using continuous sites only and one using continuous and manual sites, with standard diagnostics and cross-validation (CV) methods. We also assessed if the kriging of final model residuals reduced spatial autocorrelation and improved model CV results. LUR coefficients for the best-performing model were applied to predictors for 2015–2021 and gridded at 100 m to estimate population-weighted exposure.The continuous sites-only model and combined continuous and manual sites models had CV-R2 values of 0.59 (root-mean-square error [RMSE]: 9.4 μg/m3) and 0.54 (RMSE: 8.3 μg/m3), respectively, and both included the satellite NO2 predictor. Kriging residuals increased the CV-R2 of the combined model to 0.70 (RMSE: 7.2 μg/m3) but offered no improvement for the continuous site model. National population-weighted average NO2 was 22.1 μg/m3 in 2019. We estimated over 92% of the Indian population was exposed to annual NO2 exceeding the WHO air quality guideline (10 μg/m3). In Delhi, Mumbai, and Kolkata, an estimated 45%, 100%, and 100% of the population, respectively, experienced annual NO2 levels that surpassed Indian standards (40 μg/m3). To our knowledge, this is the first such long-term NO2 LUR model specific to India, and predictions are available to interested researchers.

One–third substitution of nitrogen with cow manure or biochar greatly reduced N2O emission and carbon footprint in saline–alkali soils

The rapid expansion of farmland and long−term excessive nitrogen (N) application have caused huge environmental risks in fragile ecosystems facing global warming. Partially substituting N fertilizer with organic fertilizers offers an alternative field management strategy to alleviate the pressure of the ecological environment. To this end, the influence of one−third substitution of N fertilizer with cow manure or biochar field experiment was conducted under maize in Tarim River Basin since 2019. Five treatments with three replications were applied: CK (Fallow); no fertilization (0 N); conventional N fertilizer (N; N: 300 kg N ha−1, organic fertilizer: 0 kg N ha−1); one−third substitution of N with biochar (NB; N: 200 kg N ha−1, Biochar: 100 kg N ha−1) and one−third substitution of N with cow manure (NM; N: 200 kg N ha−1, Cow manure: 100 kg N ha−1) under maize season in saline−alkali soils. The greenhouse gas (GHG) emissions, net ecosystem carbon budget (NECB), soil organic carbon (SOC), maize yield, carbon footprint (CF), and yield carbon footprint (CFy) were analyzed from 2021 to 2022. The results showed that NB treatment decreased the average cumulative CO2 emissions by 21 %, while NM treatment showed no difference compared to N treatment. NB and NM treatments reduced the average cumulative N2O emissions (−61 %, −49 %), CF (−68 %, −10 %), CFy (−66 %, −19 %) and increased maize yield (+3 %, +2 %), SOC storage (+43 %, +6 %), NECB (+80 %, +24 %), and agronomic N use efficiency (ANUE) (+5 %, +3 %), compared to N treatment. NB treatment had the lowest emission factors (EF) (0.19 %) and the highest sustainability index (1.58) compared to NM treatment (0.26 %, 0.61) and N treatment (0.53 %, 0.84). To sum up, substituting one−third of N fertilizer with biochar or manure in saline−alkali soils was proved to be a multi−benefit strategy to increase yields and reduce GHG emissions and CF.

Significant diurnal variations in nitrous oxide (N2O) emissions from two contrasting habitats in a large eutrophic lake (Lake Taihu, China)

Algae and macrophytes in lake ecosystems regulate nitrous oxide (N2O) emissions from eutrophic lakes. However, knowledge of diurnal N2O emission patterns from different habitats remains limited. To understand the diurnal patterns and driving mechanisms of N2O emissions from contrasting habitats, continuous in situ observations (72 h) of N2O fluxes from an algae-dominated zone (ADZ) and reed-dominated zone (RDZ) in Lake Taihu were conducted using the Floating Chamber method. The results showed average N2O emission fluxes of 0.15 ± 0.06 and 0.02 ± 0.04 μmol m−2 h−1 in the ADZ and RDZ in autumn, respectively. The significantly higher (p < 0.05) N2O fluxes in the ADZ were mainly attributed to differences in nitrogen (N) levels. The results also showed significant diurnal differences (p < 0.05) in the N2O emission fluxes within the ADZ and RDZ, and daytime fluxes were significantly higher (p < 0.05) than nighttime fluxes. The statistical results indicated that N2O emissions from the ADZ were mainly driven by diurnal variations in N loading and the dissolved oxygen (DO) concentration, and those from the RDZ were more influenced by DO, redox potential, and pH. Finally, we determined the proper time for routine monitoring of N2O flux in the two habitats. Our results highlight the importance of considering diverse habitats and diurnal variations when estimating N2O budgets at a whole-lake scale.

Air pollution impacts from warehousing in the United States uncovered with satellite data

Regulators, environmental advocates, and community groups in the United States (U.S.) are concerned about air pollution associated with the proliferating e-commerce and warehousing industries. Nationwide datasets of warehouse locations, traffic, and satellite observations of the traffic-related pollutant nitrogen dioxide (NO2) provide a unique capability to evaluate the air quality and environmental equity impacts of these geographically-dispersed emission sources. Here, we show that the nearly 150,000 warehouses in the U.S. worsen local traffic-related air pollution with an average near-warehouse NO2 enhancement of nearly 20% and are disproportionately located in marginalized and minoritized communities. Near-warehouse truck traffic and NO2 significantly increase as warehouse density and the number of warehouse loading docks and parking spaces increase. Increased satellite-observed NO2 near warehouses underscores the need for indirect source rules, incentives for replacing old trucks, and corporate commitments towards electrification. Future ground-based monitoring campaigns may help track impacts of individual or small clusters of facilities.

Contribution of the postharvest period to soil N2O emissions from arable Mediterranean crops

Soil nitrous oxide (N2O) emissions are a relevant contributor to the global warming potential of Mediterranean agro-ecosystems and therefore should be accurately quantified. Here, we investigated the quantitative relevance of considering postharvest N2O measurements when calculating annual soil N2O emissions from herbaceous crops (excluding rice). Data from 25 studies conducted in Mediterranean climates were compiled from a variety of crops and cropping systems, soil types, tillage practices, and nitrogen (N) fertilizer management practices. The differences between cumulative N2O emissions in the cropping period (preharvest emissions) and in the postharvest period were evaluated through a meta-analysis, as were the maximum N2O peaks in both periods and the resultant N2O emission factors (EFs). The relative contribution of the postharvest period to total cumulative N2O emissions was a mean 26%, but showed high variability. The average N2O EFs in the field experiments included in this study were 0.21% and 0.27% when not considering and when considering the postharvest period, respectively. The relative and absolute contribution of postharvest emissions was significantly greater for winter cereals than for either horticultural crops or maize. The maximum preharvest fluxes were higher than the maximum postharvest fluxes in 72% of the observations, but notable postharvest N2O peaks after soil rewetting were obtained in some studies. On average, postharvest emissions in nonfertilized plots were similar to those in fertilized winter crops. Other factors such as N source (greater relevance for organic fertilizers, particularly in summer crops), N rate, tillage intensity and soil texture significantly affected the amount of postharvest emissions. Taking measurements during the postharvest period in Mediterranean cropping systems are encouraged in studies that include winter crops, use of organic fertilizers or have unbalanced N rates. Our results may contribute to improving N2O measurement protocols and to re-evaluating N2O EFs in Mediterranean and semiarid areas.

Carbon to Nitrogen Ratio in Forage Plants in South Kalimantan's Oil Palm-Cattle Integration Area

The main cause of climate change is confirmed to originate from greenhouse gas emissions from human activities. Human activities such as burning fossil fuels, land use changes, population growth, and the accumulation of greenhouse gases. This research aims to determine the species of plants, organic C/N content, and to compare N2O emissions in oil palm plantations integrated with cattle farming. The research method used a survey approach in two sampling areas: oil palm plantations integrated with cattle and oil palm plantations without cattle integration. In each location, 5 plots were created, with each plot consisting of 3 subplots as replications from the edge towards the oil palm plantation, resulting in a total of 30 subplots for both locations. Parameters collected included plant species, organic C/N content, and the amount of N2O emissions. The research results showed that there are 5 plant species growing in both integrated and non-integrated oil palm plantation areas: Ageratum conyzoides, Panicum brevifolium , Centotheca longilamina Ohwi, Brachiaria decumbens dan Athyrium filex femina. Integrated and non-integrated land areas significantly affect carbon storage in both leaves and stems. Integrated land has a C/N ratio in leaves of 30.15-40.86%, while in non-integrated areas, it is 27.95-34.15%, and in stems, it ranges from 38.07-55.25% and 32.15-48.46% of total dry biomass. The average N2O gas emissions in non-integrated land are 4.6 N m²/hour, while in integrated oil palm plantations with cattle, it is 5.6 N m²/hour. The difference in N2O values between the two locations is within reasonable limits. In conclusion, oil palm plantations can be integrated with cattle for sustainable agriculture