Environmental Concern In China Research Articles

Uncovering the evolution of ozone pollution in China: A spatiotemporal characteristics reconstruction from 1980 to 2021

Ozone pollution emerged as a significant environmental concern in China in recent years. Given the enduring impact of anthropogenic activities on the atmosphere, understanding the long-term evolutionary patterns of ozone pollution is crucial for effective pollution mitigation strategies. However, there have been limited studies to reconstruct spatiotemporal continuity ozone concentrations in China since 1980. In this research, monthly MDA8 ozone concentrations from 1980 to 2021 were first estimated by reproducing the numerical relations between ozone pollution and the atmospheric environment based on a machine learning approach. The verification results from temporal, spatial, and sample-based cross-validation methods demonstrated the model performance in simulating MDA8 ozone concentration spatiotemporally, with correlation coefficients (R) ranging from 0.76 to 0.79, mean square error (RMSE) ranging from 22.72 μg·m−3 to 24.28 μg·m−3, and mean absolute error (MAE) ranging from 17.06 μg·m−3 to 18.25 μg·m−3. The evolution of ozone pollution in China can be delineated into two phases, characterized by an increasing trend since 2001, coinciding with significant rises in average annual temperature and hot weather frequency over the past four decades. The 90th percentile of ozone concentration from 2001 to 2021 increased by 1.79% compared to the period from 1980 to 2001. Notably, ozone episodes have expanded beyond summer months, partly due to global warming and frequent extreme climate events, contributing to an annual temperature increase of 0.03 °C. Despite several pollutant emission restrictions since 2013, the ozone pollution in China has persisted due to the increased emissions of VOCs. Spatially, severe ozone pollution hotspots are evident in Xinjiang province, the Jing-Jin-Ji urban agglomeration, and Northeast China, with notable increases observed in Tibet and the Guangdong-Hong Kong-Macao Greater Bay Area over the past six years. Moreover, the influence factors were identified by the average reduction of node impurity calculation. The evolution of ozone pollution was inextricably linked to solar radiation and atmospheric temperature, which played pivotal positive roles in ozone formation. Whilst, there is significant heterogeneity in the effect of meteorological conditions on ozone concentrations due to the disparity between land and oceanic climates.

Composition and Reactivity of Volatile Organic Compounds and the Implications for Ozone Formation in the North China Plain

Enhanced ozone (O3) pollution has emerged as a pressing environmental concern in China, particularly for densely populated megacities and major city clusters. However, volatile organic compounds (VOCs), the key precursors to O3 formation, have not been routinely measured. In this study, we characterize the spatial and temporal patterns of VOCs and examine the role of VOCs in O3 production in five cities (Dongying (DY), Rizhao (RZ), Yantai (YT), Weihai (WH), and Jinan (JN)) in the North China Plain (NCP) for two sampling periods (June and December) in 2021 through continuous field observations. Among various VOC categories, alkanes accounted for the largest proportion of VOCs in the cities. For VOCs, chemical reactivities, aromatic hydrocarbons, and alkenes were dominant contributors to O3 formation potential (OFP). Unlike inland regions, the contribution to OFP from OVOCs increased greatly at high O3 concentrations in coastal regions (especially YT). Model simulations during the O3 episode show that the net O3 production rates were 27.87, 10.24, and 10.37 ppbv/h in DY, RZ, and JN. The pathway of HO2 + NO contributed the most to O3 production in JN and RZ, while RO2 + NO was the largest contributor to O3 production in DY. The relative incremental reactivity (RIR) revealed that O3 formation in DY was the transitional regime, while it was markedly the VOC-limited regime in JN and RZ. The O3 production response is influenced by NOx concentration and has a clear daily variation pattern (the sensitivity is greater from 15:00 to 17:00). The most efficiencies in O3 reduction could be achieved by reducing NOx when the NOx concentration is low (less than 20 ppbv in this study). This study reveals the importance of ambient VOCs in O3 production over the NCP and demonstrates that a better grasp of VOC sources and profiles is critical for in-depth O3 regulation in the NCP.

Assessing heavy metal contamination in Amomum villosum Lour. fruits from plantations in Southern China: Soil-fungi-plant interactions

Amomum villosum Lour. fruit is a common healthy food widely cultivated in southern China. Heavy metal contamination of farmland soils has becomes a serious environmental concern in China. Heavy metals in soil can be introduced into the food chain and pose health risks to humans. However, microbial communities may play beneficial roles in plants grown in metal-polluted soils. This study aimed to assess the potential health risks of heavy metals in soils and A. villosum fruits from different production areas and to explore the soil-microbe-plant regulation pattern for heavy metals in A. villosum fruits. Soil and A. villosum fruit samples were collected from nine planting fields in four provinces of southern China. The results showed that soils from seven areas were polluted with heavy metals to different degrees. Cr and Mn were the most serious contaminating elements. However, the accumulation of heavy metals in A. villosum fruit was negligible with no expected human health risks. Partial least squares path analysis of structural equation modeling showed that the accumulation of heavy metals in A. villosum fruits was influenced by multiple factors. More importantly, the PLS-SEM revealed that the heavy metal content in A. villosum fruits was indirectly affected by soil heavy metals through the regulation of the microbial community. Furthermore, some fungal phyla (e.g., Ascomycota and Chytridiomycota) and genera (e.g., Mucor) were related to the heavy metal content in the soil and in A. villosum fruits. The results of this study verified that soil fungal community play an important role in the accumulation of heavy metals in A. villosum fruits. Using fungi provides a potential biological strategy for reducing the health risk posed by heavy metals in food.

Detection of Multi-dimensional Driving Forces of Public Environmental Concern in China: Based on Spatial Heterogeneity Perspectives

Detection of Multi-dimensional Driving Forces of Public Environmental Concern in China: Based on Spatial Heterogeneity Perspectives

Air pollution estimation under air stagnation—A case study of Beijing

Air pollution continues to be a major environmental concern in China. The wind‐driven transmission poses difficulties in understanding the air pollution patterns at the local level. The main objective of this study is to offer a straightforward approach for investigating the temporal trends and meteorological effects on the air pollutant concentrations during the generation process without being confounded by the complex wind‐driven transmission effect. We focus on the hourly data of the three most common air pollutants: PM2.5, NO, and CO under air stagnation in Beijing, China, during 2014–2017. We find that the local pollution levels under air stagnation in Beijing have decreased over the years; winter is the severest month of the year; Sunday is the clearest day of the week. Our model also interpolates the air pollutant concentrations at sites without monitoring stations and provides a map of air pollution concentrations under air stagnation. The results could be used to identify locations where air pollutants easily accumulate.

The Aggravation of Summertime Nocturnal Ozone Pollution in China and Its Potential Impact on the Trend of Nitrate Aerosols

AbstractTropospheric ozone (O3) concentration continued to increase over past years, thereby becoming a growing environmental concern in China. Most studies have focused on the analysis of daily maximum 8‐hr O3 concentration, while there is still a dearth of investigations of nocturnal O3. Here, by analyzing the data of 1,313 sites from the China National Environmental Monitoring Center, we show a remarkable increase in the nocturnal O3 concentration during summertime of 2015–2019 in most regions of China, revealing an aggravation of nocturnal O3 pollution. Combining with a GeoDetector model and statistical analysis, we clarify that the aggravation of nocturnal O3 pollution is mainly caused by reduction in both ambient nitrogen dioxide (NO2) concentration and wet scavenging in recent years. We further reveal that the increasing O3 may have enhanced the nocturnal particulate nitrate () formation through N2O5 heterogeneous hydrolysis, and thereby driving the variation and long‐term trend of nocturnal .

The effect of anthropogenic emission, meteorological factors, and carbon dioxide on the surface ozone increase in China from 2008 to 2018 during the East Asia summer monsoon season

Abstract. Despite the implementation of the Clean Air Action Plan by the Chinese government in 2013, the issue of increasing surface ozone (O3) concentrations remains a significant environmental concern in China. In this study, we used an improved regional climate–chemistry–ecology model (RegCM-Chem-YIBs) to investigate the impact of anthropogenic emissions, meteorological factors, and CO2 changes on summer surface O3 levels in China from 2008 to 2018. Compared to its predecessor, the model has been enhanced concerning the photolysis of O3 and the radiative impacts of CO2 and O3. The investigations showed anthropogenic emissions were the primary contributor to the O3 increase in China, responsible for 4.08–18.51 ppb in the North China Plain. However, changed meteorological conditions played a crucial role in decreasing O3 in China and may have a more significant impact than anthropogenic emissions in some regions. Changed CO2 played a critical role in the variability of O3 through radiative forcing and isoprene emissions, particularly in southern China, inducing an increase in O3 on the southeast coast of China (0.28–0.46 ppb) and a decrease in southwest and central China (−0.51 to −0.11 ppb). Our study comprehensively analyzed O3 variation across China from various perspectives and highlighted the importance of considering CO2 variations when designing long-term O3 control policies, especially in high-vegetation-coverage areas.

Risk assessment and source apportionment of heavy metalloids from typical farmlands provinces in China

Potentially toxic metals in farmland soil have recently become a significant environmental concern in China. In this study, the occurrence and distribution of eight (8) heavy metals (HMs) were investigated from 54 topsoil samples obtained across 18 provinces. Human health and ecological hazards associated with HMs were assessed through different risk characterization indices and their sources predicted. The statistically mean concentrations of HMs ranged from 0.08 to 70.05 mg kg−1, which were below the determined threshold values for agricultural lands according to the Chinese National Standard (GB 15618–2018). The respective ecological risk index (Eri) of HMs revealed that they posed a lower risk (Eri<40) but their potential cumulative ecological risk (RI) was determined as a considerable risk (300 ≤ RI < 600). Spatial distribution and heterogeneities of HMs were found to be highly concentrated in the southern parts (e.g., Yunnan, Guangdong) of China, particularly for Arsenic (As), Zinc (Zn), and Chromium (Cr). PMF model was found capable of efficiently elucidating respective sources of HMs across the studied provinces as most were impacted by geological/pedogenic and anthropogenic activities (e.g., agricultural, industrial discharge fallouts). Probabilistic health risk assessment indicated that the non-carcinogenic risk (NCR) and total carcinogenic risk (TCR) of HMs in both adults and children were low and acceptable.

Holocene dust storm variations over northern China: transition from a natural forcing to an anthropogenic forcing

Asian dust storms have long been a major environmental concern in China, affecting the lives of about one billion people. However, it is unclear whether the mechanisms responsible for Asian dust storms during the Holocene varied on different timescales, and thus it is unclear whether there was a shift from a natural forcing to an anthropogenic forcing of dust storms. We reconstructed a high-resolution Holocene record of dust storms from the sediments of an undisturbed alpine lake on the Chinese Loess Plateau. We found that Asian dust storm activity generally increased during the Holocene, with the largest fluctuations occurring during the past 2000 years. The increase in dust storm activity was in contrast to the decrease in East Asian winter monsoon (EAWM) intensity during the Holocene, indicating that the EAWM played a limited role in modulating dust storms. By contrast, the increase in dust storms corresponded to a decrease in EASM precipitation. This demonstrates that EASM precipitation was the dominant control of dust storm activity on a millennial timescale, because decreased EASM precipitation expanded the desert area and thus increased the dust storm activity. The increasing intensity of human activity in the region since the Bronze Age resulted in an acceleration of dust storm activity against the background of decreased EASM precipitation. As human disturbance continued to intensify, beginning at least at ~2 cal ka BP, increased dust storms were closely linked to increasing human populations in the dust source regions, and there is a strong temporal coherence between increased dust storms and higher EASM precipitation. This was completely different from when natural processes are dominant. During that period, fewer dust storms occurred during periods of a strengthened EASM. Therefore, there was a shift from a natural forcing to an anthropogenic forcing of dust storms on a multi-decadal to centennial timescale, and was a mode in which “human activity overtook the EASM as the dominant control of the Earth surface system”.

Evaluation of Livelihood Sustainability in the Context of Natural Forest Land Degradation Vulnerability: A Case Study of Five Counties in China

Land degradation, especially natural forest land degradation (NFLD), is a severe environmental concern in China. This natural disaster itself and its derivative control policies have caused some impacts on surrounding farmers’ livelihood level and strategies, but the literature on the sustainable livelihood of different households in NFLD vulnerability is limited, and there is an urgent need to bridge the gap and conduct studies on the sustainable livelihood of Changting, Libo, Lixian, Menghai and Wuxi, the typical NFLD-prone areas in China. A new livelihood sustainability index (LSI) including livelihood asset, livelihood strategy and sustainability engagement is constructed to assess the basic situation. The results showed that: (1) The overall LSI of five NFLD areas was not high, and the social, financial and natural assets, in particular, were relatively low. A disparity was found among the five areas, and the rank sequence of the LSI value was sorted in a descending order: Changting &gt; Menghai &gt; Libo &gt; Lixian &gt; Wuxi. (2) In detail, farmers in Changting had the relative highest LSI because of the inherent high value of livelihood assets, which constrain the scores of the livelihood strategy and sustainability engagement. (3) Households in Libo, Menghai and Lixian had middle level LSI scores. The relative low livelihood assets in Libo and Menghai drove parts of local farmers to carry out off-farm/forestry employment, leading to high scores of livelihood strategy, while farmers in Lixian had lower livelihood diversification scores and higher sustainability engagement due to their working content for the local forestry bureau. (4) The low scores of the livelihood asset and sustainability engagement restricted farmers in Wuxi. A discussion of LSI in the NFLD vulnerability was conducted to determine the characteristics and analyze the reasons. Accordingly, targeted policy recommendations were proposed to realize a sustainable livelihood in NFLD areas.

The effect of cultural and psychological characteristics on the purchase behavior and satisfaction of electric vehicles: A comparative study of US and China

AbstractThis is a viewpoint paper that compares the psychological and behavioral characteristics of electric vehicle (EV) owners in the United States and China. EV is viewed as the dominant next wave of automotive technology and this research is a cross‐cultural study of the two most important automotive markets in the world. In particular, this study surveyed actual EV users in the United States and China, and compared their psychological and behavioral characteristics. The study also shows that motivation for EV usage, reasons for purchase, and satisfaction are different across the two countries. US owners showed a higher propensity to innovate and greater knowledge of EVs than Chinese owners. Even though there was no difference between the two groups in terms of environmental concern, Chinese owners cited reputation and signaling social responsibility as being important considerations in their purchase of an EV, while US owners cited technological innovativeness, driving pleasure, and lower maintenance cost. Satisfaction with EV ownership was affected by economic benefit and environmental concern in China and innovation in the United States. This study shows how culture and stage of motorization are reflected in consumer behavior and satisfaction regarding EVs. EV manufacturers need to be aware of these differences when targeting the two markets.

Educational attainment and environmental concern in China: An instrumental variable approach

Formal education is theorised to be an essential vehicle to promote and trigger pro‐environmental attitudes and behavioural changes among citizens via the increase of public awareness and concern. However, robust estimations of its causal effect on individuals’ concern for the environment are scarce. This study aimed to estimate the effect of educational attainment on environmental concern in China, addressing the problem of endogeneity. China is the largest emitter of CO2 and faces severe environmental problems due to its rapid process of industrialisation and urbanisation. The findings show that educational attainment has a robust positive causal effect on environmental concern in China. After addressing potential endogeneity issues using an instrumental variable approach, the effect is stronger than a conventional ordinal least squares estimation. Thus, education is a crucial path of action to promote environmental concern and subsequent pro‐environmental behaviour in China.

Characteristics and Applications of Sewage Sludge Biochar Modified by Ferrous Sulfate for Remediating Cr(VI)-Contaminated Soils

Background. Soil contamination by hexavalent chromium is becoming a main environmental concern in China. This study developed a sewage sludge biochar modified by FeSO4 (CHBC) as a new reductant for Cr(VI)-contaminated soil. The effectiveness of CHBC-stabilized Cr(VI)-contaminated soil was investigated. Methods. Typical industrial Cr(VI)-contaminated soil in China was chosen as the medium. The total and Cr(VI) contents of the contaminated soil were 1014.6 and 973.5 mg/kg, respectively. The effectiveness of the Cr(VI)-contaminated soil stabilized by CHBC was investigated by the leaching test (US EPA method 1312), the simplified bioaccessibility extraction test (US EPA 2007 protocol and British Geological Survey), alkaline digestion (US EPA method 3060A), sequential extraction (BCR sequential extraction procedure), X-ray diffraction, and the risk assessment code test. Results. Results show that CHBC substantially reduced the leachability and Cr(VI) content of the contaminated soil. The leachability and content of Cr(VI) were lower than the thresholds of the Environmental Quality Standards of Soil in China for civil reuse and the China Environmental Quality Standards of surface water for civil use when the soil was stabilized with 10% dosage of CHBC. Conclusion. CHBC is highly efficient in stabilizing Cr(VI) and can effectively reduce the leachability and bioavailability of Cr in contaminated soil and thus feasible for stabilizing Cr(VI)-contaminated soil and shows potential for application in the field.

Carbon footprint of a typical pomelo production region in China based on farm survey data

Greenhouse gas emissions are a central environmental concern in China, and quantifying the carbon footprint of crop production can help identify key options for mitigating greenhouse gas emissions from agriculture. Using two-year farm survey data from a typical pomelo production area in China, the carbon footprint of a pomelo orchard was assessed by quantifying the greenhouse gas emissions from farming inputs and operations with a full life cycle assessment methodology. The carbon emission and carbon sequestration levels were 19.9 and 3.43 t CO2 eq ha−1, respectively. The farm carbon footprint and product carbon footprint were 16.5 t CO2 eq ha−1 and 0.33 t CO2 eq t−1, respectively, which were 3.8 and 1.5 times greater than the corresponding mean values for other fruit orchards in different areas of the world. Compared with farms with low yield and high carbon footprint, farms with high yield and low carbon footprint reduced nitrogen fertilizer input significantly, by 44.7%. Furthermore, the yield of farms which with high yield and low carbon footprint increased significantly by 69.4%, and the farm carbon footprint and product carbon footprint significantly decreased by 40.7% and 67.2%, respectively, compared to those of farms with low yield and high carbon footprint. The synthetic nitrogen fertilizer application rate was significantly linearly correlated with, and contributed 84.7% to the carbon footprint of pomelo production. The relationships between the carbon footprint and the nitrogen partial factor productivity also indicated that improving nitrogen utilization can effectively reduce greenhouse gas emissions. In addition, based on group analysis, the difference in carbon footprint among farm groups was also mainly due to nitrogen fertilization. Reducing costs can significantly improve carbon efficiency without affecting the economic benefit at similar yield levels. Therefore, the carbon intensity of pomelo production in China could be reduced primarily by reducing excessive nitrogen fertilizer application and potentially increasing nitrogen use efficiency. Apart from this, these differences could be implemented by modifying farming fertilization strategies and farm size. Overall, this study highlights the importance of strengthening nitrogen management in pomelo production based on agricultural practices as well as upscaling farm size, which could achieve higher yields with lower greenhouse gas emissions and thereby avoid tradeoffs between productivity and carbon costs.

Modeling of the Complex Modulus of Asphalt Mastic with Biochar Filler Based on the Homogenization and Random Aggregate Distribution Methods

The disposal of agricultural straw has been a severe environmental concern in China and many other countries. In this study, the complex modulus of using biochar converted from straw as an alternative mineral filler in asphalt mastic was investigated through both laboratory tests and modeling. The experimental results indicated that the biochar can provide asphalt mastic higher stiffness than the conventional granite mineral filler. It was believed that the special porous structure of biochar providing a thicker coating layer of mineral filler increases the stiffness modulus of asphalt mastic. To consider this factor into the micromechanical model, a modified generalized self-consistent model (MGSCM) with a coating layer was proposed. Besides, the finite element (FE) microstructural model with a coating layer generated by random aggregate distribution method was used to numerically evaluate the effect of the coating layer on the complex modulus of asphalt mastics. The predicted results indicated that the generalized self-consistent model (MGSCM) with a coating layer is an efficient and accurate model for predicting the complex modulus of asphalt mastics. Moreover, the FE modeling proved that the coating layer can significantly improve the complex modulus of asphalt mastics. Therefore, the experiments and modeling carried out in this study provided insight for biochar applications to improve the performance of asphalt mixtures.

Industrial disposal processes for treatment of polychlorinated dibenzo-p-dioxins and dibenzofurans in municipal solid waste incineration fly ash.

Hazardous waste disposal is a serious environmental concern in China. Therefore, in this study, industrial trials were conducted in a low-temperature thermal degradation facility, a tunnel kiln, and a shaft kiln to effectively treat dioxins in municipal solid waste incineration (MSWI) fly ash. The results indicated that the low-temperature thermal degradation facility efficiently decomposed polychlorinated dibenzo-p-dioxins and dibenzofurans in the MSWI fly ash. Additionally, the concentrations of dioxins in the treated fly ash and exhaust gas were lower than the suggested standard limits and the degradation ratio of dioxins was ∼99%. Therefore, treated fly ash characterized by acceptable dioxin risks could be utilized for the production of non-fired building materials. The results from the tunnel kiln indicated complete decomposition of the dioxins in the firing and insulating sections. However, the addition of fly ash in the tunnel kiln increased the concentration of dioxins in the flue gas. This can be primarily attributed to the heterogeneous catalytic synthesis reaction in the low-temperature section of the tunnel kiln. The results from the shaft kiln indicated degradation of at least 22% of the dioxins in the ash. The dioxin concentration in the flue gas was lower than the national standard while that in the clinker was within a reasonable limit. Furthermore, the environmental risks were significantly reduced at fly ash addition ratios lower than 3%.

Social Capital’s Influence on Environmental Concern in China: An Analysis of the 2010 Chinese General Social Survey

This study examines the ways in which social capital influences people’s environmental concern in China. Using data obtained from the 2010 Chinese General Social Survey, we measure social capital through social networks and trust. We find that the ways people think about and act toward others influence the ways they think about and act toward the environment. The structural equation modeling results suggest that one’s connections with others, including socializing with relatives and friends as well as general social networking, are significantly and positively related to various dimensions of environmental concern. Greater trust is positively related to one’s willingness to make sacrifices for the benefit of the environment but is also negatively related to perceived dangerousness of pollution. Our findings highlight the value of social capital in promoting environmental concern. We discuss these findings in the context of existing literature, and propose policy implications and suggest directions for future research.

Responses of greenhouse-gas emissions to land-use change from rice to jasmine production in subtropical China

We studied the impacts of an increasingly common change in land use from paddy field to jasmine fields on the emission of greenhouse gases (GHGs), which have supposed the transformation of more than 1200 ha only in the last decade in the surroundings of Fuzhou city in response to economic changes. The possible increases that this can suppose constitutes and environmental concern in China. We studied areas dedicated to rice crop that have been partially converted to jasmine cultivation with some parts still kept as rice fields. Emissions of CO2, CH4 and N2O varied significantly among the seasons. CO2 and CH4 cumulative emissions and the global-warming potential (GWP) of these emissions were significantly lower in the jasmine than the paddy field. N2O emission, N2O cumulative emission, however, were higher in the jasmine than the paddy field, despite in some concrete studied periods the differences were not statistically significant. The total decrease in GHG emissions from the conversion from rice to jasmine production was strongly influenced by the indirect effects of various changes in soil conditions. The expected changes due to the great differences in water and fertilization use and management and organic matter input to soil between these two crops were in great part due to modified soil traits. According to structural equation models, the strong direct effects of the change from rice to Jasmine crop reducing the emissions of CO2 and N2O were partially decreased by the indirect effects of crop type change decreasing soil pH and soil [Fe2+] for CO2 emissions and by decreasing soil salinity and soil [Fe3+] for N2O emissions. The negative effects of the crop conversion on CH4 emissions were mostly due to the globally negative indirect effects on soil conditions, by decreases in soil salinity, water content and [Fe2+]. Soil salinity, water content, pH, [Fe2+], [Fe3+] and [total Fe] were significantly lower in the jasmine than the paddy field, but temperature had the opposite pattern. CO2 emissions were generally correlated positively with salinity, temperature, and water content and negatively with [Fe3+] and [total Fe] in both fields. CH4 emissions were positively correlated with salinity, temperature, water content and pH in both fields. N2O emissions were positively correlated with temperature and were negatively correlated with water content, pH, [Fe2+], [Fe3+] and [total Fe] in both fields. CO2 was the most important GHG for the GWPs, and the total GWP was significantly lower for the jasmine than for the rice cropland field. The change in the land use in this area of paddy fields will decreased the global GHG emission, and the effect on the GWPs was mostly due to changes in soil properties.

Human activities and urban air pollution in Chinese mega city: An insight of ozone weekend effect in Beijing

Ozone pollution has become a major environmental concern in China, especially in mega cities with intensified human activities, which can impact air quality and human health. This study explores the different characteristics of ozone and ozone weekend effect (OWE) in different seasons in places (e.g. urban center, inner urban areas, suburban areas and natural background areas) with different degree of urbanization and intensity of human activities and the effect of urbanization on ozone at different scales in Beijing. The annual daily average ozone concentration in Beijing was 56μg/m3, with the maximum of 98.0 μg/m3 occurred in summer and the minimum of 27 μg/m3 in winter. Spatially, annual daily average ozone concentration increased along the urban-rural gradient. The annual ozone concentration was 6% higher at weekend than that on weekdays. Seasonally, the ozone concentration on weekend was 18% higher than that on workdays in summer, 4% in autumn, and 10% in winter, but was 10% lower in spring, indicating that the ozone production regime in different seasons could be different. Influence of urbanization on OWE varied by scale. At the city scale, OWE was more pronounced in urban centers than suburban areas, but at the local scale, OWE tended to decrease with the increase degree of urbanization.

Profiles and potential health risks of heavy metals in soil and crops from the watershed of Xi River in Northeast China

Heavy metal soil contamination is a major environmental concern in China and has drawn significant public attention in recent years. The present study assessed the human health risk of four heavy metals (cadmium, lead, mercury, and zinc) through soil exposure and dietary intake in the watershed of Xi River, west of Shenyang, Liaoning Province, northeast China. Concentrations of Cd, Pb, Hg, and Zn were determined in 411 soil samples and 59 crop samples collected from this area. The health risks of heavy metal exposure via soil ingestion, inhalation, dermal contact, and dietary intake of crops were further estimated; total hazard index values were 1.15, 1.33, and 2.03 for the adult male, adult female, and children, respectively, and the total cancer risk was 3.7 × 10−3 for the local residents. Among the four investigated heavy metals, Cd was the primary pollutant posing health risks. The estimated non-carcinogenic and carcinogenic risks posed by the studied heavy metals were above the acceptable levels proposed by the U.S. EPA. Dietary intake of contaminated crops was identified as the predominant pathway for human heavy metal exposure in this area, suggesting that soil heavy metals can cause more harm when transported to the food chain. Overall, our findings suggest that the Xi River watershed is unsuitable for growing agricultural products, and more effective controls should be taken to curb future heavy metal pollution in the area.