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Ammonia mitigation campaign with smallholder farmers improves air quality while ensuring high cereal production. NATURE FOOD 2023; 4:751-761. [PMID: 37653045 DOI: 10.1038/s43016-023-00833-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 08/07/2023] [Indexed: 09/02/2023]
Abstract
Reducing cropland ammonia (NH3) emissions while improving air quality and food supply is a challenge, particularly in China where there are millions of smallholder farmers. We tested the effectiveness of a tailored nitrogen (N) management strategy applied to wheat-maize cropping systems in 'demonstration squares' across Quzhou County in the North China Plain. The N-management techniques included optimal N rates, deep fertilizer placement and application of urease inhibitors, implemented through cooperation between government, researchers, businesses and smallholders. Compared with conventional local smallholder practice, our NH3 mitigation campaign reduced NH3 volatilization from wheat and maize by 49% and 39%, and increased N-use efficiency by 28% and 40% and farmers' profitability by 25% and 19%, respectively, with no detriment to crop yields. County-wide atmospheric NH3 and fine particulate matter (with aerodynamic diameter <2.5 μm) concentrations decreased by 40% and 8%, respectively. County-wide net benefits were estimated at US$7.0 million. Our demonstration-square approach shows that cropland NH3 mitigation and improved air quality and farm profitability can be achieved simultaneously by coordinated actions at the county level.
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Crop-specific ammonia volatilization rates and key influencing factors in the upland of China - A data synthesis. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 336:117676. [PMID: 36967697 DOI: 10.1016/j.jenvman.2023.117676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 03/03/2023] [Accepted: 03/03/2023] [Indexed: 06/18/2023]
Abstract
Ammonia (NH3) is an important alkaline reactive nitrogen (Nr) species which is involved in global nitrogen (N) biogeochemical cycling, but which has negative impacts on the environment and human health. In order to better understand and control the NH3 loss potential in soil-upland crop systems in China, an integrated data analysis including 1302 observations from 236 published articles between 1980 and 2021 was conducted. The typical NH3 volatilization rate (AVR) and the main factors influencing AVR in the major Chinese upland crops (maize, wheat, openfield vegetables and greenhouse vegetables and others) were estimated and analyzed. The mean AVR for maize, wheat, openfield vegetables and greenhouse vegetables were 7.8%, 5.3%, 8.4% and 1.8%. The most important influencing factors were fertilizer placement, meteorological conditions (especially temperature and rainfall) and soil properties (especially SOM). Subsurface N application produced a significantly lower AVR compared to surface application. High N recovery efficiency and N agronomic efficiency were generally associated with low AVRs. In conclusion, high N application rates, inefficient application methods and the use of loss-prone N fertilizer types are the main factors responsible for high AVRs in major Chinese croplands.
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The application of machine learning to air pollution research: A bibliometric analysis. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 257:114911. [PMID: 37154080 DOI: 10.1016/j.ecoenv.2023.114911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 03/27/2023] [Accepted: 04/10/2023] [Indexed: 05/10/2023]
Abstract
Machine learning (ML) is an advanced computer algorithm that simulates the human learning process to solve problems. With an explosion of monitoring data and the increasing demand for fast and accurate prediction, ML models have been rapidly developed and applied in air pollution research. In order to explore the status of ML applications in air pollution research, a bibliometric analysis was made based on 2962 articles published from 1990 to 2021. The number of publications increased sharply after 2017, comprising approximately 75% of the total. Institutions in China and United States contributed half of all publications with most research being conducted by individual groups rather than global collaborations. Cluster analysis revealed four main research topics for the application of ML: chemical characterization of pollutants, short-term forecasting, detection improvement and optimizing emission control. The rapid development of ML algorithms has increased the capability to explore the chemical characteristics of multiple pollutants, analyze chemical reactions and their driving factors, and simulate scenarios. Combined with multi-field data, ML models are a powerful tool for analyzing atmospheric chemical processes and evaluating the management of air quality and deserve greater attention in future.
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Reactive N emissions from cropland and their mitigation in the North China Plain. ENVIRONMENTAL RESEARCH 2022; 214:114015. [PMID: 35944622 DOI: 10.1016/j.envres.2022.114015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 07/23/2022] [Accepted: 07/27/2022] [Indexed: 06/15/2023]
Abstract
Excessive application of chemical nitrogen (N) fertilizer and inefficient N management are still common in the North China Plain, leading to large reactive N (Nr) losses and pollution, threatening environmental security and public health. Three improved N management practices (33% reduction in N applied (OU), OU combined with partial organic fertilizer substitution (UOM) and the urea in UOM amended with a urease inhibitor (ULOM)) together with no N application (CK) and farmers' conventional practice (CU) were tested on a maize-wheat rotation at Quzhou, Hebei, North China Plain (NCP). Nr emissions were related to WFPS (Water Filled Pore Space), soil mineral N (NH4+-N and NO3--N) and soil temperature. Nr emissions and yield-scaled Nr emissions were significantly reduced by partial substitution of organic fertilizer for chemical fertilizer: NH3 emissions were reduced by 55.8-62.4%. Using a urease inhibitor (Limus®), further reduced NH3 emissions by 40.2-64.5%. Yield-scaled NH3 emissions were, on average, reduced by 60.0% and 55.2% in the maize and wheat growing season, respectively, relative to the UOM treatment. Long-term application of organic fertilizer had a significant positive effect on N use efficiency (NUE). Overall, the study shows that appropriated N management such as reducing the N application rate, partial substitution of chemical N by organic N and using a urease inhibitor can reduce Nr emissions and promote NUE in the North China Plain. The methods corresponding to the ULOM and UOM treatments were the most and second most effective, respectively, with high net economic benefits.
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Increasing importance of ammonia emission abatement in PM2.5 pollution control. Sci Bull (Beijing) 2022; 67:1745-1749. [PMID: 35945953 PMCID: PMC9353663 DOI: 10.1016/j.scib.2022.07.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 03/28/2022] [Accepted: 03/28/2022] [Indexed: 11/26/2022]
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Global maps of soil temperature. GLOBAL CHANGE BIOLOGY 2022; 28:3110-3144. [PMID: 34967074 PMCID: PMC9303923 DOI: 10.1111/gcb.16060] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/27/2021] [Indexed: 05/05/2023]
Abstract
Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications.
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Evolution of secondary inorganic aerosols amidst improving PM 2.5 air quality in the North China plain. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 281:117027. [PMID: 33857715 DOI: 10.1016/j.envpol.2021.117027] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 03/19/2021] [Accepted: 03/24/2021] [Indexed: 06/12/2023]
Abstract
The Clean Air Action implemented by the Chinese government in 2013 has greatly improved air quality in the North China Plain (NCP). In this work, we report changes in the chemical components of atmospheric fine particulate matter (PM2.5) at four NCP sampling sites from 2012/2013 to 2017 to investigate the impacts and drivers of the Clean Air Action on aerosol chemistry, especially for secondary inorganic aerosols (SIA). During the observation period, the concentrations of PM2.5 and its chemical components (especially SIA, organic carbon (OC), and elemental carbon (EC)) and the frequency of polluted days (daily PM2.5 concentration ≥ 75 μg m-3) in the NCP, declined significantly at all four sites. Asynchronized reduction in SIA components (large decreases in SO42- with stable or even increased NO3- and NH4+) was observed in urban Beijing, revealing a shift of the primary form of SIA, which suggested the fractions of NO3- increased more rapidly than SO42- during PM2.5 pollution episodes, especially in 2016 and 2017. In addition, unexpected increases in the sulfur oxidation ratio (SOR) and the nitrogen oxidation ratio (NOR) were observed among sites and across years in the substantially decreased PM2.5 levels. They were largely determined by secondary aerosol precursors (i.e. decreased SO2 and NO2), photochemical oxidants (e.g. increased O3), temperature, and relative humidity via gas-phase and heterogeneous reactions. Our results not only highlight the effectiveness of the Action Plan for improving air quality in the NCP, but also suggest an increasing importance of SIA in determining PM2.5 concentration and composition.
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Changes of nitrogen deposition in China from 1980 to 2018. ENVIRONMENT INTERNATIONAL 2020; 144:106022. [PMID: 32795750 DOI: 10.1016/j.envint.2020.106022] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/30/2020] [Accepted: 07/28/2020] [Indexed: 05/25/2023]
Abstract
China has experienced a dramatic change in atmospheric reactive nitrogen (Nr) emissions over the past four decades. However, it remains unclear how nitrogen (N) deposition has responded to increases and/or decreases in Nr emissions. This study quantitatively assesses temporal and spatial variations in measurements of bulk and calculated dry N deposition in China from 1980 to 2018. A long-term database (1980-2018) shows that bulk N deposition peaked in around 2000, and had declined by 45% by 2016-2018. Recent bulk and dry N deposition (based on monitoring from 2011 to 2018) decreased from 2011 to 2018, with current average values of 19.4 ± 0.8 and 20.6 ± 0.4 kg N ha-1 yr-1, respectively. Oxidized N deposition, especially dry deposition, decreased after 2010 due to NOx emission controls. In contrast, reduced N deposition was approximately constant, with reductions in bulk NH4+-N deposition offset by a continuous increase in dry NH3 deposition. Elevated NH3 concentrations were found at nationwide monitoring sites even at urban sites, suggesting a strong influence of both agricultural and non-agricultural sources. Current emission controls are reducing Nr emissions and deposition but further mitigation measures are needed, especially of NH3, built on broader regional emission control strategies.
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Environmental impacts of nitrogen emissions in China and the role of policies in emission reduction. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2020; 378:20190324. [PMID: 32981443 PMCID: PMC7536030 DOI: 10.1098/rsta.2019.0324] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Atmospheric reactive nitrogen (Nr) has been a cause of serious environmental pollution in China. Historically, China used too little Nr in its agriculture to feed its population. However, with the rapid increase in N fertilizer use for food production and fossil fuel consumption for energy supply over the last four decades, increasing gaseous Nr species (e.g. NH3 and NOx) have been emitted to the atmosphere and then deposited as wet and dry deposition, with adverse impacts on air, water and soil quality as well as plant biodiversity and human health. This paper reviews the issues associated with this in a holistic way. The emissions, deposition, impacts, actions and regulations for the mitigation of atmospheric Nr are discussed systematically. Both NH3 and NOx make major contributions to environmental pollution but especially to the formation of secondary fine particulate matter (PM2.5), which impacts human health and light scattering (haze). In addition, atmospheric deposition of NH3 and NOx causes adverse impacts on terrestrial and aquatic ecosystems due to acidification and eutrophication. Regulations and practices introduced by China that meet the urgent need to reduce Nr emissions are explained and resulting effects on emissions are discussed. Recommendations for improving future N management for achieving 'win-win' outcomes for Chinese agricultural production and food supply, and human and environmental health, are described. This article is part of a discussion meeting issue 'Air quality, past present and future'.
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Impact of 13-years of nitrogen addition on nitrous oxide and methane fluxes and ecosystem respiration in a temperate grassland. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 252:675-681. [PMID: 31185356 DOI: 10.1016/j.envpol.2019.03.069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Revised: 02/23/2019] [Accepted: 03/17/2019] [Indexed: 06/09/2023]
Abstract
Nitrogen (N) fertilizer application and atmospheric N deposition will profoundly affect greenhouse gas (GHGs) emissions, especially nitrous oxide (N2O) and methane (CH4) fluxes and ecosystem respiration (Re, i.e. CO2 emissions). However, the impacts of long-term N inputs and the often associated N-induced soil acidification on GHG fluxes in arid and semi-arid ecosystems, especially temperate grasslands, are still uncertain. An in situ experiment was conducted to investigate the effect of long-term (13-years) N addition on N2O and CH4 fluxes and Re from a temperate grassland in Inner Mongolia, northeast China, from April 2017 to October 2018. Soil pH values in the 0-5 cm layer receiving 120 (N120) and 240 (N240) kg N ha-1 decreased from 7.12 to 4.37 and 4.18, respectively, after 13 years of N inputs. Soil CH4 uptake was significantly reduced, but N2O emission was enhanced significantly by N addition. However, N addition had no impact on Re. Structural Equation Modeling indicated that soil NH4+-N content was the dominant control of N2O emissions, but with less effect of the decreasing pH. In contrast, CH4 uptake was generally controlled by soil pH and NO3--N content, and Re by forb biomass. The measured changes in N2O and CH4 fluxes and Re from temperate grassland will have a profoundly impact on climate change.
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The Growth and N Retention of Two Annual Desert Plants Varied Under Different Nitrogen Deposition Rates. FRONTIERS IN PLANT SCIENCE 2019; 10:356. [PMID: 30972090 PMCID: PMC6443888 DOI: 10.3389/fpls.2019.00356] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 03/07/2019] [Indexed: 06/09/2023]
Abstract
Nitrogen (N) partitioning between plant and soil pools is closely related to biomass accumulation and allocation, and is of great importance for quantifying the biomass dynamics and N fluxes of ecosystems, especially in low N-availability desert ecosystems. However, partitioning can differ among species even when growing in the same habitat. To better understand the variation of plant biomass allocation and N retention within ephemeral and annual species we studied the responses of Malcolmia Africana (an ephemeral) and Salsola affinis (an annual) to N addition, including plant growth, N retention by the plant and soil, and N lost to the environment using 15N (double-labeled 15NH4 15NO3 (5.16% abundance) added at 0, 0.8, 1.6, 3.2, and 6.4 g pot-1, equivalent to 0, 15, 30, 60, and 120 kg N ha-1) in a pot experiment. Higher N addition (N120) inhibited plant growth and biomass accumulation of the ephemeral but not the annual. In addition, the aboveground:belowground partitioning of N (the R:S ratio) of the ephemeral decreased with increasing N addition, but that of the annual increased. The N input corresponding to maximum biomass and 15N retention of the ephemeral was significantly less than that of the annual. The aboveground and belowground retention of N in the ephemeral were significantly less than those of the annual, except at low N rates. The average plant-soil system recovery of added 15N by the ephemeral was 70%, significantly higher than that of the annual with an average of 50%. Although the whole plant-soil 15N recovery of this desert ecosystem decreased with increasing N deposition, our results suggested that it may vary with species composition and community change under future climate and elevated N deposition.
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Cumulative and partially recoverable impacts of nitrogen addition on a temperate steppe. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2018; 28:237-248. [PMID: 29113017 DOI: 10.1002/eap.1647] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 09/20/2017] [Accepted: 10/19/2017] [Indexed: 06/07/2023]
Abstract
Atmospheric nitrogen (N) deposition has been shown to decrease biodiversity and change nutrient cycles in terrestrial ecosystems. However, our understanding of ecological responses to chronic N addition and ecological recovery of grassland from N enrichment is limited. Here we present evidence from an 11-year grassland experiment with a range of N addition rates (0, 30, 60, 120, 240, and 480 kg N·ha-1 ·yr-1 ) in Inner Mongolia, China. Chronic N addition led to a reduction in species richness, Shannon diversity index, and soil pH and an increase in aboveground biomass, foliar N, and soil mineral N. High N addition rates (240 and 480 kg N·ha-1 ·yr-1 ) showed significant effects in the first and second years, which stabilized over time. Nitrogen addition at low rates (30 and 60 kg N·ha-1 ·yr-1 ) took longer (e.g., three years or more) to achieve significant effects. The negative impacts of high N addition (480 kg N·ha-1 ·yr-1 ) were reduced and species richness, Shannon diversity index, and soil pH showed a limited but rapid recovery with the cessation of N addition. Our findings suggest serious and cumulative impacts of N addition on plant and soil communities but the potential for partial system recovery over time if N inputs decline or cease.
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Impacts of water and nitrogen addition on nitrogen recovery in Haloxylon ammodendron dominated desert ecosystems. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 601-602:1280-1288. [PMID: 28605846 DOI: 10.1016/j.scitotenv.2017.05.202] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 05/22/2017] [Accepted: 05/22/2017] [Indexed: 06/07/2023]
Abstract
Desert ecosystems are likely to change in response to global climate change and nitrogen (N) deposition. The effects of increased precipitation and N deposition on plant growth and the N cycle largely depend on N allocation and N recovery efficiency in the plant-soil ecosystem, but there is limited research on this in desert ecosystems. Here we report results using double-labeled 15NH415NO3 (30 and 60kgNha-1yr-1) as a tracer under ambient (no additional water addition) and enhanced precipitation (60mm water addition) in a Haloxylon ammodendron dominated ecosystem in the Gurbantunggut Desert of Northwest China. Herbaceous plants were a significantly larger sink for added 15N than the H. ammodendron trees, and N retention varied with water and N addition, relative to growing season precipitation. The retention of added 15N varied within the components of H. ammodendron, with the stems retaining most, followed by the assimilation branches. Soil was the dominant sink for added 15N, in which the topsoil and subsoil respond differently to water and N addition over the two-year period. Nitrogen relative recovery percentage in the whole ecosystem ranged from 43% to 61%, lower than average recovery rate in temperate forests; N tracer recovery percentage significantly increased with water addition but decreased with enhanced N deposition. Future N cycling in central Asian deserts will depend on changes in precipitation.
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Disaggregated N 2O emission factors in China based on cropping parameters create a robust approach to the IPCC Tier 2 methodology. ATMOSPHERIC ENVIRONMENT (OXFORD, ENGLAND : 1994) 2015; 122:272-281. [PMID: 26865831 PMCID: PMC4705909 DOI: 10.1016/j.atmosenv.2015.09.054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
China accounts for a third of global nitrogen fertilizer consumption. Under an International Panel on Climate Change (IPCC) Tier 2 assessment, emission factors (EFs) are developed for the major crop types using country-specific data. IPCC advises a separate calculation for the direct nitrous oxide (N2O) emissions of rice cultivation from that of cropland and the consideration of the water regime used for irrigation. In this paper we combine these requirements in two independent analyses, using different data quality acceptance thresholds, to determine the influential parameters on emissions with which to disaggregate and create N2O EFs. Across China, the N2O EF for lowland horticulture was slightly higher (between 0.74% and 1.26% of fertilizer applied) than that for upland crops (values ranging between 0.40% and 1.54%), and significantly higher than for rice (values ranging between 0.29% and 0.66% on temporarily drained soils, and between 0.15% and 0.37% on un-drained soils). Higher EFs for rice were associated with longer periods of drained soil and the use of compound fertilizer; lower emissions were associated with the use of urea or acid soils. Higher EFs for upland crops were associated with clay soil, compound fertilizer or maize crops; lower EFs were associated with sandy soil and the use of urea. Variation in emissions for lowland vegetable crops was closely associated with crop type. The two independent analyses in this study produced consistent disaggregated N2O EFs for rice and mixed crops, showing that the use of influential cropping parameters can produce robust EFs for China.
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Impacts of pollution controls on air quality in Beijing during the 2008 Olympic Games. JOURNAL OF ENVIRONMENTAL QUALITY 2011; 40:37-45. [PMID: 21488491 DOI: 10.2134/jeq2010.0360] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Air pollution has become one of the main environmental concerns in China since the 1980s due to China's rapid economic growth and resultant pollution. However, it is difficult to directly evaluate the anthropogenic contribution to air pollution in China. The 2008 Olympic Games in Beijing provided a unique opportunity for testing the contribution of anthropogenic pollution because of the clean-up controls on air quality in Beijing enforced over the period of the Games. In this case study, we monitored the concentrations of major air pollutants before, during, and after the Olympics at a suburban site in Beijing. Atmospheric concentrations of PM10, PM2.5, NH3, NO2, SO2, and the particulate ions NH4+, NO3-, SO4(2-) Ca2+, Mg2+, and K+ all decreased during the Olympic period because of strict emission controls, compared with the same period from 2005 to 2007. For example, the average PM10 concentration (61 microg m(-3)) during the Olympics was only 37% of that (166 microg m(-3)) in the same month (August) from 2005 to 2007. However, just 1 mo and 1 yr after the Games had ended, mean concentrations of these pollutants had increased significantly again. This rapid "recovery' of air pollutant concentrations after the Olympics suggests that China needs to implement long-lasting decreases in its air pollution in Beijing and other major cities.
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Abstract
Increasing the inputs of nutrients has played a major role in increasing the supply of food to a continually growing world population. However, focusing attention on the most important nutrients, such as nitrogen (N), has in some cases led to nutrient imbalances, some excess applications especially of N, inefficient use and large losses to the environment with impacts on air and water quality, biodiversity and human health. In contrast, food exports from the developing to the developed world are depleting soils of nutrients in some countries. Better management of all essential nutrients is required that delivers sustainable agriculture and maintains the necessary increases in food production while minimizing waste, economic loss and environmental impacts. More extensive production systems typified by 'organic farming' may prove to be sustainable. However, for most of the developed world, and in the developing world where an ever-growing population demands more food, it will be essential to increase the efficiency of nutrient use in conventional systems. Nutrient management on farms is under the control of the land manger, the most effective of whom will already use various decision supports for calculating rates of application to achieve various production targets. Increasingly, land managers will need to conform to good practice to achieve production targets and to conform to environmental targets as well.
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Changes in the heavy metal contents of soil from the Park Grass Experiment at Rothamsted Experimental Station. Anal Bioanal Chem 1996; 354:699-702. [PMID: 15067475 DOI: 10.1007/s0021663540699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/1995] [Accepted: 08/12/1995] [Indexed: 10/26/2022]
Abstract
The classical Rothamsted Experiments allow to contribute to current research. The heavy metal content of soil and hay samples have been measured with ICP-AES from a control and a fertilized plot of the Park Grass Experiment. Today a difference of 1.2 can be observed in the pH levels of the control and fertilized plots; the pH level of the control plot has decreased about 1.0, that of the fertilized plot about 2.2 as a result of 150 years of acid deposition and fertilization. The changes in the pH levels has caused many changes in the heavy metal content of the top layer of the soil. Using different extraction methods (e.g., ammonium acetate, EDTA, and sequential analysis), the heavy metal content of different fractions have been estimated. In the control plot, the Zn, Cd and Pb content increased. In the fertilized plot, the Pb and Cd contents have also increased because of atmospheric deposition and small amounts of lead in the fertilizer. The available form of Cd and Pb increased in both the control and the fertilized plots.
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Abstract
Phenoxybenzene (diphenyl
ether) has been converted into the 4-sulfonyl chloride (1) which on condensation
with various nucleophilic reagents gave a range of sulfonyl derivatives (2-11),
such as the azide, hydrazides, and hydrazones. The sulfonyl chloride (1), by
nitration, gave 4-(4'-nitrophenoxy)benzenesulfonyl chloride (12) which was
similarly converted into sulfonyl derivatives (13-18). Reaction of o-chlorophenol with p-chloronitrobenzene afforded 2-chlorophenyl 4-nitrophenyl ether;
with chlorosulfonic acid this gave the sulfonyl chloride (19) which was
converted into the sulfonyl derivatives (20)-(25). Condensation of
2,6-dichlorophenol with p-chloronitrobenzene
similarly gave the substituted diphenyl ether (26) which with chlorosulfonic
acid afforded 3,5- dichloro-4-(4'-nitrophenoxy)benzenesulfonyl chloride (27).
The phenoxybenzenesulfonyl derivatives are of interest as potential herbicides
and their algicidal and antibacterial properties are briefly discussed.
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