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Urban and Regional Nitrogen Cycle and Risk Management

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A special issue of Atmosphere (ISSN 2073-4433). This special issue belongs to the section "Air Quality".

Deadline for manuscript submissions: closed (14 June 2024) | Viewed by 16577

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Special Issue Editors

Dr. Chaofan Xian

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State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
Interests: ecosystem health; environmental management; urban and regional sustainability; society and environment; environmental footprint; pollution source apportionment; nitrogen cycling
Special Issues, Collections and Topics in MDPI journals

Dr. Yu-Sheng Shen

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Guest Editor

Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 China
Interests: urban science and sustainability; healthy city and public health; suicide and mental health; climate change and environmental management; quantitative methodology and artificial intelligence
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Dr. Cheng Gong

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Guest Editor

State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
Interests: ecosystem service; urban forest; stable isotope; air pollution; big data mining
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Atmosphere dedicates this Special Issue to the urban and regional nitrogen cycle with urbanzition, which should be addressed by risk management as anthropogenic interventions have globally alterded the multi-scale distributions of reactive nitrogen, resulting in the greenhouse effect, acid rain, eurtophication and reductions in biodiversity. Therefore, the ‘nitrogen cascade’ effect induced by nitrogen cycle disruption has been regonized as the third most important global environmental problem after biodiversity loss and global warming. In China, the world's largest anthropogenic reactive nitrogen producer, significant progress has been made in recent decades in nitrogen polltuion alleviation. Despite this, previous studies have revealed that insignificant reductions in national reactive nitrogen releasing, mainly contributed by agricultural production (62–69%), are still observed, and 55–59% reactive nitrogen was emitted to the atmosphere. However, based on most city-scale case studies, residental livelihood is supposed to be the main source of reactive nitrogen releases induced by a disrupted nitrogen cycle.

In agricultural, industrial and residential activites, maintaining well-ordered nitrogen cycles with fewer negative environmental impacts is linked to the correct and efficienct risk-management of reactive nitrogen. Possible actions to reduce reactive nitrogen being released to the environment include proper nitrogen management within the production and consumption cycles of essencial resources (e.g., food, energy, water), which could be supported by anthropogenic approachs (e.g., environmental pollution monitoring, environmentally friendly technology and residents’ behavior) and natural-based approaches including nitrogen retention by greenland, wetland, farmland and bare land. The experimental approaches and modeling techniques can help the research in this respect. Different study methods can be adopted to address this Special Issue, depending on the scale of the urban and regional nitrogen cycles.

Authors are welcome to submit their contributions concerning the analysis of sources, sinks and flows of nitrogen cycles and relevant risk management towards SDGs. Field and modeling studies concerning the nitrogen pollution and driving factors, as well as the relaionships between nitrogen cycle and other cycles of water, carbon, phosphorus, sulphur, etc., are also encouraged.

Dr. Chaofan Xian
Dr. Yu-Sheng Shen
Dr. Cheng Gong
Guest Editors

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Keywords

reactive nitrogen cycle
air pollution/air pollutants
environmental monitoring and assessment
ecosystem service
environmental footprint
material flow analysis
nitrogen source apportionment
nitrogen and carbon coupling
food, energy and water nexus
urban and regional sustainability

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Published Papers (12 papers)

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Research

17 pages, 3425 KiB

Open AccessArticle

Does Atmospheric Nitrogen Deposition Confer a Competitive Advantage to Invasive Bidens pilosa L. over Native Pterocypsela laciniata (Houtt.) Shih?

by Chuang Li, Yue Li, Yingsheng Liu, Shanshan Zhong, Huanshi Zhang, Zhelun Xu, Zhongyi Xu, Daolin Du and Congyan Wang

Atmosphere 2024, 15(7), 825; https://doi.org/10.3390/atmos15070825 - 10 Jul 2024

Viewed by 622

Abstract

One of the key reasons for the success of invasive plants is the functional differences between invasive plants and native plants. However, atmospheric nitrogen deposition may disrupt the level of available nitrogen in soil and the functional differences between invasive plants and native plants, which may alter the colonization of invasive plants. Thus, there is a pressing necessity to examine the effects of atmospheric nitrogen deposition containing different nitrogen components on the functional differences between invasive plants and native plants. However, the progress made thus far in this field is not sufficiently detailed. This study aimed to elucidate the effects of artificially simulated nitrogen deposition containing different nitrogen components (i.e., nitrate, ammonium, urea, and mixed nitrogen) on the functional differences between the Asteraceae invasive plant Bidens pilosa L. and the Asteraceae native plant Pterocypsela laciniata (Houtt.) Shih. The study was conducted over a four-month period using a pot-competitive co-culture experiment. The growth performance of P. laciniata, in particular with regard to the sunlight capture capacity (55.12% lower), plant supporting capacity (45.92% lower), leaf photosynthetic area (51.24% lower), and plant growth competitiveness (79.92% lower), may be significantly inhibited under co-cultivation condition in comparison to monoculture condition. Bidens pilosa exhibited a more pronounced competitive advantage over P. laciniata, particularly in terms of the sunlight capture capacity (129.43% higher), leaf photosynthetic capacity (40.06% higher), and enzymatic defense capacity under stress to oxidative stress (956.44% higher). The application of artificially simulated nitrogen deposition was found to facilitate the growth performance of monocultural P. laciniata, particularly in terms of the sunlight capture capacity and leaf photosynthetic area. Bidens pilosa exhibited a more pronounced competitive advantage (the average value of the relative dominance index of B. pilosa is ≈ 0.8995) than P. laciniata under artificially simulated nitrogen deposition containing different nitrogen components, especially when treated with ammonium (the relative dominance index of B. pilosa is ≈ 0.9363) and mixed nitrogen (the relative dominance index of B. pilosa is ≈ 0.9328). Consequently, atmospheric nitrogen deposition, especially the increased relative proportion of ammonium in atmospheric nitrogen deposition, may facilitate the colonization of B. pilosa via a stronger competitive advantage. Full article

(This article belongs to the Special Issue Urban and Regional Nitrogen Cycle and Risk Management)

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22 pages, 11038 KiB

Open AccessArticle

Study on Mapping and Identifying Risk Areas for Multiple Particulate Matter Pollution at the Block Scale Based on Local Climate Zones

by Wen Wu, Ruihan Liu and Yu Tang

Atmosphere 2024, 15(7), 794; https://doi.org/10.3390/atmos15070794 - 30 Jun 2024

Viewed by 904

Abstract

As China’s urbanization process accelerates, the issue of air pollution becomes increasingly prominent and urgently requires improvement, based on the fact that environmental conditions such as meteorology and topography are difficult to change. Therefore, relevant optimization studies from the perspective of architectural patterns are operable to mitigate pollution. This paper takes the Wenhua Road block in Shenyang, China, as the research object; obtains the concentration data of three kinds of particulate matter through fixed and mobile monitoring; and analyzes the spatial distribution characteristics of Local Climate Zones ( LCZ) and particulate matter in the block based on the ArcGIS platform, identifies high-risk areas, and excavates the influence of LCZ on the concentrations of three kinds of particulate matter. The results show that the spatial distribution characteristics of PM₁, PM_2.5, and PM₁₀ under the same pollution level are relatively similar, while the spatial heterogeneity of the distribution of the same particulate matter under different pollution levels is higher. The time-weighted results show that the PM₁ pollution level in the block ranges from 44 to 51 μg/m³, PM_2.5 ranges from 75 to 86 μg/m³, and PM₁₀ ranges from 87 to 99 μg/m³. The pollution hot spots throughout the year are located in the central, eastern and western parts of the study area. In terms of the relationship between the LCZ and particulate matter, with the increase in the particulate matter diameter, the correlation between the three kinds of particulate matter and LCZ are all enhanced. The built-up LCZ always has a larger average concentration of particulate matter than that of the natural LCZ, and building height and building density are the main factors causing the difference. In the optimal design of the risk area, the proportion of natural vegetation or water surface should be increased and the building height should be properly controlled and the building density should be reduced in the renewal of the urban building form. This study will largely improve the spatial refinement of the optimization of urban architectural patterns oriented to mitigate particulate matter pollution. Full article

(This article belongs to the Special Issue Urban and Regional Nitrogen Cycle and Risk Management)

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19 pages, 23022 KiB

Open AccessArticle

Investigation into Spatial and Temporal Differences in Carbon Emissions and Driving Factors in the Pearl River Delta: The Perspective of Urbanization

by Ziya Gao, Dafang Wu, Zhaojun Wu and Lechun Zeng

Atmosphere 2024, 15(7), 782; https://doi.org/10.3390/atmos15070782 - 29 Jun 2024

Viewed by 638

Abstract

Urbanization is a significant indicator of city progress, and as urbanization advances, carbon emissions exhibit an increasing trend that must not be disregarded. Therefore, it is imperative to thoroughly examine the spatial and temporal variations as well as the factors influencing carbon emissions during the urbanization process. In this paper, based on the 2009–2019 PRD region, carbon emissions are measured from energy consumption, industrial production process, solid waste, and wastewater according to the IPCC coefficients, and spatial and spatial differences in carbon emissions are combined with spatial analysis and the drivers analyzed using the gray correlation scale. The results show that: (1) The total carbon emissions in the PRD region have been increasing over the study period, and the distribution of total carbon emissions shows a pattern of “strong in the east and weak in the west”, with energy consumption accounting for the highest proportion of carbon emissions. (2) The global Moran Index of carbon emissions in the PRD has been decreasing, with low and low clustering concentrated in Shaoguan and Zhaoqing, high and high clustering concentrated in Dongguan and Shenzhen, and low and high clustering concentrated in Shenzhen and Guangzhou, with cold spots mainly concentrated in Zhaoqing and hot spots mainly distributed in Guangzhou, Shenzhen, and Dongguan. (3) The degree of economic growth has a substantial influence on carbon emissions in the PRD cities, and the influence of technical advancement has intensified. Guangzhou City is propelled by low-carbon regulations that have a more equitable influence on all elements. Zhuhai City has a more significant influence on energy intensity, while Foshan City has a more noticeable decrease in the effect of foreign investment. To address the issue of carbon emissions, the government should establish appropriate rules to regulate carbon emissions in areas with high emissions, foster collaborative efforts across cities, and encourage the growth of environmentally friendly enterprises. Full article

(This article belongs to the Special Issue Urban and Regional Nitrogen Cycle and Risk Management)

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16 pages, 6712 KiB

Open AccessArticle

Evaluating the Conservation Status and Effectiveness of Multi-Type Protected Areas for Carbon Sequestration in the Loess Plateau, China

by Sony Lama, Jingjing Zhang and Xiaofeng Luan

Atmosphere 2024, 15(7), 764; https://doi.org/10.3390/atmos15070764 - 27 Jun 2024

Viewed by 967

Abstract

Evaluating the conservation effectiveness of multiple types of protected areas (PAs) on carbon sequestration services can enhance the role of PAs in mitigating global warming. Here, we evaluated the conservation status and effectiveness of national parks, nature reserves, forest parks, geo-parks, and scenic spots on carbon sequestration within the Loess Plateau throughout 2000–2020. The results show that all existing PA types have good representation and conservation effectiveness on carbon sequestration. Nature reserves are the most representative of carbon sequestration but are the least effective in protecting carbon sequestration and are the only ones that are weekly effective in protecting critical carbon sequestration. The main factors influencing these results are PA size, 2000 precipitation, slope, change rate of evapotranspiration, PA rank, and 2000 evapotranspiration. We suggest upgrading the critical carbon sequestration distribution areas in scenic spots, forest parks and geo-parks to national parks or nature reserves in the future and implementing appropriate protection and restoration measures in low carbon sequestration areas within grassland and wild plant nature reserves to help achieve the goal of carbon neutrality early. Full article

(This article belongs to the Special Issue Urban and Regional Nitrogen Cycle and Risk Management)

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18 pages, 6916 KiB

Open AccessArticle

Litter Mass Loss of the Invasive Rhus typhina L. and Native Koelreuteria paniculata Laxm. Trees Alters Soil N-Fixing Bacterial Community Composition under Different N Forms

by Yue Li, Chuang Li, Huiyuan Cheng, Zhelun Xu, Shanshan Zhong, Mawei Zhu, Yuqing Wei, Zhongyi Xu, Daolin Du, Congyan Wang and Huanshi Zhang

Atmosphere 2024, 15(4), 424; https://doi.org/10.3390/atmos15040424 - 29 Mar 2024

Viewed by 1126

Abstract

Soil N-fixing bacterial (NFB) community may facilitate the successful establishment and invasion of exotic non-nitrogen (N) fixing plants. Invasive plants can negatively affect the NFB community by releasing N during litter decomposition, especially where N input from atmospheric N deposition is high. This study aimed to quantitatively compare the effects of the invasive Rhus typhina L. and native Koelreuteria paniculata Laxm. trees on the litter mass loss, soil physicochemical properties, soil enzyme activities, and the NFB. Following N supplementation at 5 g N m⁻² yr⁻¹ in four forms (including ammonium, nitrate, urea, and mixed N with an equal mixture of the three individual N forms), a litterbag-experiment was conducted indoors to simulate the litter decomposition of the two trees. After four months of decomposition, the litter cumulative mass losses of R. typhina under the control, ammonium chloride, potassium nitrate, urea, and mixed N were 57.93%, 57.38%, 58.69%, 63.66%, and 57.57%, respectively. The litter cumulative mass losses of K. paniculata under the control, ammonium chloride, potassium nitrate, urea, and mixed N were 54.98%, 57.99%, 48.14%, 49.02%, and 56.83%, respectively. The litter cumulative mass losses of equally mixed litter from both trees under the control, ammonium chloride, potassium nitrate, urea, and mixed N were 42.95%, 42.29%, 50.42%, 46.18%, and 43.71%, respectively. There were antagonistic responses to the co-decomposition of the two trees. The litter mass loss of the two trees was mainly associated with the taxonomic richness of NFB. The form of N was not significantly associated with the litter mass loss in either species, the mixing effect intensity of the litter co-decomposition of the two species, and NFB alpha diversity. Litter mass loss of R. typhina was significantly higher than that of K. paniculata under urea. The litter mass loss of the two trees under the control and N in four forms mainly affected the relative abundance of numerous NFB taxa, rather than NFB alpha diversity. Full article

(This article belongs to the Special Issue Urban and Regional Nitrogen Cycle and Risk Management)

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14 pages, 1956 KiB

Open AccessCommunication

Is the Invasive Plant Amaranthus spinosus L. More Competitive than the Native Plant A. tricolor L. When Exposed to Acid Deposition with Different Sulfur–Nitrogen Ratios?

by Yue Li, Chuang Li, Shanshan Zhong, Zhelun Xu, Jun Liu, Zhongyi Xu, Mawei Zhu, Congyan Wang and Daolin Du

Atmosphere 2024, 15(1), 29; https://doi.org/10.3390/atmos15010029 - 26 Dec 2023

Cited by 1 | Viewed by 1100

Abstract

The functional differences between invasive plants and coexisting native plants can affect the invasion process of the former because invasive plants and coexisting native plants are exposed to similar or even identical environmental pressures. Acid deposition is an important component of atmospheric pollution, and acid deposition with different sulfur–nitrogen ratios may affect the invasion process of invasive plants by shifting the functional differences and differences in the growth performance between the invasive and coexisting native plants. It is crucial to analyze the functional indices and growth performance of these plants when exposed to acid deposition with different chemical compositions to assess the ecological impacts of atmospheric pollution on the growth performance of invasive plants. This study aimed to evaluate the functional differences and growth performance between the invasive plant Amaranthus spinosus L. and the native plant A. tricolor L. in mono- and mixed culture when exposed to an acid deposition with different sulfur–nitrogen ratios, including sulfur-rich acid deposition (sulfur–nitrogen ratio = 5:1), nitrogen-rich acid deposition (sulfur–nitrogen ratio = 1:5), and mixed acid deposition (sulfur–nitrogen ratio = 1:1). The acidity of the three types of simulated acid deposition was set at pH = 5.6 and pH = 4.5, respectively, with distilled water as a control (pH = 7.0). The competition experiment between A. spinosus and A. tricolor was conducted in the greenhouse. Amaranthus spinosus exhibited a strong growth performance over A. tricolor in the mixed culture, mainly via the increased leaf photosynthetic capacity. The competitiveness for light acquisition, leaf photosynthetic capacity, and enzymatic defense capacity under stress of A. spinosus may be vital to its growth performance. The lower pH acid deposition had imposed a greater reduction in the growth performance of both Amaranthus species than the higher pH acid deposition. Sulfur-rich acid deposition was more toxic to the growth performance of both Amaranthus species than nitrogen-rich acid deposition. Amaranthus spinosus was more competitive than A. tricolor, especially when exposed to acid deposition, compared with just distilled water. Thus, acid deposition, regardless of the sulfur–nitrogen ratio, may facilitate the invasion process of A. spinosus via the stronger growth performance. Full article

(This article belongs to the Special Issue Urban and Regional Nitrogen Cycle and Risk Management)

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20 pages, 1662 KiB

Open AccessArticle

Analysis of Carbon Emission Characteristics and Influencing Factors of Herder Households: A County-Scale Investigation of the Sanjiangyuan Region on the Qinghai–Tibet Plateau

by Changsu Song, Lu Liu, Chaofan Xian, Fan Feng and Zhiyun Ouyang

Atmosphere 2023, 14(12), 1800; https://doi.org/10.3390/atmos14121800 - 8 Dec 2023

Cited by 1 | Viewed by 1205

Abstract

With further urbanization, household consumption firmly plays a key role in China’s national carbon emissions. However, current research concerning carbon issues has mainly focused on urban household consumption, and few studies have paid attention to herder households, leading to a research gap in the field of low-carbon shifting related to nomadic economies. In this study, we interviewed more than one-thousand herder households in the Sanjiangyuan region of the Qinghai–Tibet Plateau in China. The household carbon emissions and their influencing factors were investigated across the herder households of 15 counties. Our findings revealed the following: (1) There exist differences in the amounts of household carbon emissions and their compositions in the Sanjiangyuan region. From the perspective of spatial distribution, the emission hotspots are mainly concentrated in the eastern part of the Sanjiangyuan region. (2) At the prefecture level, average personal emissions were larger in the Hainan Prefecture (3.26 t ce/year), while they were approximately 1.36 times that of the Huangnan Prefecture (2.4 t ce/year), though with smaller personal emissions. The indirect carbon emissions of the four prefectures all occupied larger percentages of household carbon emissions that were mainly contributed by food consumption and housing. (3) Family type was the main diver influencing personal carbon emissions in the Huangnan Prefecture, Guoluo Prefecture, and Yushu Prefecture. The more people living in the household, the lower the per capita carbon emissions. However, the effect size of potential carbon reductions was weakened when the number of family members rose to over three. (4) We propose that grazing prohibitions and low-carbon dietary shifts would contribute to low-carbon herder livelihoods, especially for small-sized households that should be peer-to-peer targeted by regional government propaganda, which may help to strengthen the implementation of in-depth low-carbon promotions across the Sanjiangyuan region and even the overall Qinghai–Tibet Plateau. Full article

(This article belongs to the Special Issue Urban and Regional Nitrogen Cycle and Risk Management)

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16 pages, 6605 KiB

Open AccessArticle

Insight into Municipal Reactive Nitrogen Emissions and Their Influencing Factors: A Case Study of Xiamen City, China

by Yanmin Li, Xu Yang, Shihang Wang and Shenghui Cui

Atmosphere 2023, 14(10), 1549; https://doi.org/10.3390/atmos14101549 - 11 Oct 2023

Viewed by 1404

Abstract

Reactive nitrogen (Nr) has been confirmed as an indispensable nutrient for the city ecosystem, but high-intensity human activities have led to nitrogen pollution in cities, especially in coastal cities, jeopardizing ecosystem services and human health. Despite this, the characteristics and influencing factors of Nr remain unclear in coastal cities, particularly in the context of rapid urbanization. This study used the material flow analysis method to estimate Nr emissions in Xiamen from 1995 to 2018 and evaluated the characteristics of excessive Nr emissions. The STIRPAT model was used to identify and explore factors contributing to observed Nr levels in coastal cities. As indicated by the results, (1) the quantity of Nr generated by human activities increased 3.5 times from 1995 to 2018. Specifically, the total Nr entering the water environment showed a general increase with fluctuations, exhibiting an average annual growth rate of 3.1%, increasing from 17.2 Gg to 35.1 Gg. (2) Nr loads in the nearby sea increased notably from 8.1 Gg in 1995 to 25.4 Gg in 2018, suggesting a threefold augmentation compared with surface waters and groundwater. (3) NO_x was the gaseous Nr with the greatest effect on the atmosphere in Xiamen, which was primarily due to fossil fuel consumption. (4) Population and per capita GDP were major factors contributing to Nr load in the water environment, while Nr emission to the atmosphere was influenced by population and energy consumption. These findings provide valuable insights for tailored approaches to sustainable nitrogen management in coastal cities. Full article

(This article belongs to the Special Issue Urban and Regional Nitrogen Cycle and Risk Management)

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29 pages, 9555 KiB

Open AccessArticle

Comparative Study on the Influencing Factors of the Greenhouse Gas Budget in Typical Cities: Case Studies of Beijing and Shenzhen

by Kuo Liu, Shishuai Yang, Binbin Huang, Chaofan Xian, Baolong Han, Tian Xie, Chengji Shu, Zhiwen Chen, Haoqi Wang, Haijun Wang and Fei Lu

Atmosphere 2023, 14(7), 1158; https://doi.org/10.3390/atmos14071158 - 17 Jul 2023

Viewed by 1403

Abstract

Clarifying the pattern of the urban greenhouse gas (GHG) budget and its influencing factors is the basis of promoting urban low-carbon development. This paper takes Beijing and Shenzhen—the capital city and the most rapidly developing city in China, respectively—as case studies, comprehensively accounts their GHG budgets from 2005 to 2020, and investigates and compares the factors affecting their GHG budgets. The total GHG emissions in Beijing were lowest in 2005 (160.3 TgCO₂ equivalents) and peaked at 227.7 TgCO₂ equivalents in 2019, and then decreased to 209.1 TgCO₂ equivalents in 2020. Meanwhile, the total GHG emissions in Shenzhen gradually increased from 36.0 TgCO₂ equivalents in 2005 to 121.4 TgCO₂ equivalents in 2019, and then decreased to 119.1 TgCO₂ equivalents in 2020. The energy activity sector was the greatest contributor to GHG emissions in this period, accounting for 82.5% and 76.0% of the total GHG emissions in Beijing and Shenzhen, respectively. The carbon sink of the ecosystems of these two cities could absorb only small parts of their emissions, and the neutralization rates of sinks ranged from 1.7% to 2.3% in Beijing and from 0.3% to 1.5% in Shenzhen. The enhancement of population, economic product, and consumption increased the greenhouse gas emissions in both cities. A 1% increase in population size, per capita GD (gross domestic product), and residential consumption level would increase total GHG emissions by 0.181%, 0.019%, and 0.030% in Beijing, respectively. The corresponding increases in Shenzhen would be 0.180%, 0.243%, and 0.172%, respectively. The household size had opposite effects on the two cities, i.e., a 1% increase in household size would increase GHG emissions by 0.487% in Shenzhen but reduce them by 2.083% in Beijing. Each 1% increase in secondary industry and energy intensity would reduce GHG emissions by 0.553% and 0.110% in Shenzhen, respectively, which are more significant reductions than those in Beijing. Full article

(This article belongs to the Special Issue Urban and Regional Nitrogen Cycle and Risk Management)

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14 pages, 6097 KiB

Open AccessArticle

The Bibliometric Analysis of Low-Carbon Transition and Public Awareness

by Xialu Wu and Yu-Sheng Shen

Atmosphere 2023, 14(6), 970; https://doi.org/10.3390/atmos14060970 - 1 Jun 2023

Cited by 2 | Viewed by 1863

Abstract

After the agreements of the Conference of the Parties, more and more countries announced plans to achieve net zero emissions over the coming decades and published new policies in response to the agreements. Public awareness is a crucial factor in achieving the goals of the agreements. Therefore, the study of public awareness/behavior toward the low-carbon transition is important. However, this topic lacks a comprehensive and systematic review. Thus, this study used bibliometric analysis, including performance analysis and scientific mapping analysis, to reveal research trends and clarify the status of studies in low-carbon transition and public awareness. We found that 95% of the literature on this topic was published from 2011 to 2022. Judging from keywords, the hotspots of this topic are “Sustainability”, “Energy Transition”, “Low-carbon Economy”, and “Carbon Emission Reduction”. Regarding the research field transition for this topic, environmental sciences have always been a core subject. Furthermore, economics, management, political science, and sociology have focused on this topic in recent years. Additionally, there are gaps between low-carbon policy and public awareness/behavior. Therefore, the frontier directions of low-carbon transition and public awareness include “low-carbon education”, “policies with specific guidelines”, and “worldwide collaboration”. Full article

(This article belongs to the Special Issue Urban and Regional Nitrogen Cycle and Risk Management)

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19 pages, 7612 KiB

Open AccessArticle

Driving Forces on the Distribution of Urban Ecosystem’s Non-Point Pollution Reduction Service

by Chengji Shu, Kaiwei Du, Baolong Han, Zhiwen Chen, Haoqi Wang and Zhiyun Ouyang

Atmosphere 2023, 14(5), 873; https://doi.org/10.3390/atmos14050873 - 16 May 2023

Cited by 2 | Viewed by 1656

Abstract

In the context of increasing urbanization and worsening environmental pollution, nonpoint source pollution during high-frequency rainfall has become a major ecological problem that endangers residents in cities. This study takes Shenzhen as an example. On the basis of a large number of soil sample test data, and combined with relevant environmental variables, it has drawn the high-resolution, high-precision spatial distribution maps of soil attributes within the city. In addition, this paper combines the revised universal soil loss equation and the GeoDetector model to evaluate the supply capacity of nonpoint source reduction services in the city’s ecological space and the main driving factors of spatial distribution characteristics for different types of land. The study found that increasing soil point density and combining environmental variables can help improve the accuracy of spatial mapping for soil attributes. The ME, MSE, ASE, RMSE, and RMSSE of spatial mapping all meet the accuracy evaluation criteria and are better than many existing studies; the spatial distribution characteristics of soil attributes and nonpoint source reduction services show significant differences among the whole city, secondary administrative regions, and different types of land; the GeoDetector results show that among the three main types of land use (forested land, industrial land, and street town residential land), topographic factors, habitat-quality factors, and ecosystem types have the greatest impact on the spatial differentiation characteristics of nonpoint source reduction services. Among climate factors, only precipitation factors have the greatest impact on the spatial differentiation characteristics of services. Facing the above factors, the q-values calculated by the GeoDetector are all higher than 10%. The results of this study can provide information for making better decisions on regional ecological system management and soil protection and on restoration work aimed at improving nonpoint source reduction services. Full article

(This article belongs to the Special Issue Urban and Regional Nitrogen Cycle and Risk Management)

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22 pages, 5481 KiB

Open AccessArticle

Regional/Single Station Zenith Tropospheric Delay Combination Prediction Model Based on Radial Basis Function Neural Network and Improved Long Short-Term Memory

by Xu Yang, Yanmin Li, Xuexiang Yu, Hao Tan, Jiajia Yuan and Mingfei Zhu

Atmosphere 2023, 14(2), 303; https://doi.org/10.3390/atmos14020303 - 3 Feb 2023

Cited by 3 | Viewed by 1767

Abstract

Atmospheric water vapor is an essential source of information that predicts global climate change, rainfall, and disaster-natured weather. It is also a vital source of error for Earth observation systems, such as the global navigation satellite system (GNSS). The Zenith Tropospheric Delay (ZTD) plays a crucial role in applications, such as atmospheric water vapor inversion and GNSS precision positioning. ZTD has specific temporal and spatial variation characteristics. Real-time ZTD modeling is widely used in modern society. The conventional back propagation (BP) neural network model has issues, such as local, optimal, and long short-term memory (LSTM) model needs, which help by relying on long historical data. A regional/single station ZTD combination prediction model with high precision, efficiency, and suitability for online modeling was proposed. The model, called K-RBF, is based on the machine learning algorithms of radial basis function (RBF) neural network, assisted by the K-means cluster algorithm (K-RBF) and LSTM of real-time parameter updating (R-LSTM). An online updating mechanism is adopted to improve the modeling efficiency of the traditional LSTM. Taking the ZTD data (5 min sampling interval) of 13 international GNSS service stations in southern California in the United States for 90 consecutive days, K-RBF, R-LSTM, and K-RBF were used for regions, single stations, and a combination of ZTD prediction models regarding research, respectively. Real-time/near real-time prediction results show that the root-mean-square error (RMSE), mean absolute error (MAE), coefficient of determination (R2), and training time consumption (TTC) of the K-RBF model with 13 station data are 8.35 mm, 6.89 mm, 0.61, and 4.78 s, respectively. The accuracy and efficiency of the K-RBF model are improved compared with those of the conventional BP model. The RMSE, MAE, R2, and TTC of the R-LSTM model with WHC1 station data are 6.74 mm, 5.92 mm, 0.98, and 0.18 s, which improved by 67.43%, 66.42%, 63.33%, and 97.70% compared with those of the LSTM model. The comparison experiments of different historical observation data in 24 groups show that the real-time update model has strong applicability and accuracy for the time prediction of small sample data. The RMSE and MAE of K-RBF with 13 station data are 4.37 mm and 3.64 mm, which improved by 47.70% and 47.20% compared to K-RBF and by 28.48% and 31.29% compared to R-LSTM, respectively. The changes in the temporospatial features of ZTD are considered, as well, in the combination model. Full article

(This article belongs to the Special Issue Urban and Regional Nitrogen Cycle and Risk Management)

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