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PubMed2026

Biomass burning contributions to Mexico City's atmospheric CO2 estimated using a multi-isotope approach.

Fossil fuel combustion dominates anthropogenic emissions worldwide; however, special attention should be addressed to biomass burning, since it is an increasingly important contributor under warmer, drier fire-weather conditions exacerbated by climate change. These emissions could impact the atmospheric composition of heavily urbanized environments. To assess the influence of biomass burning, along with fossil fuels combustion and soil and plant respiration on Mexico City's atmospheric composition, we conducted a year-long (December 2023-December 2024) isotopic monitoring of atmospheric CO2, combining radiocarbon (Δ14C), CO2 stable isotopes (δ13C, δ18O), and CO/CO2 ratios. Once defined the isotopic signatures and the characteristic CO/CO2 that describe the sources, we performed Monte Carlo simulations under two tracer modalities (Δ14C + CO/CO2 and Δ14C + CO2 stable isotopes) for source apportionment. Results show that during the dry season, particularly in March-April, atmospheric Δ14C values approached and overlapped background levels despite Mexico City's fossil-fuel dominance, indicating enhanced non-fossil inputs. Moreover, backward HYSPLIT trajectories supported that these elevated Δ14C values coincided with regional wildfire activity. Monte Carlo results attributed up to ∼34 %-60 % of local CO2 to biomass burning in April, followed by March with contributions of ∼31 %-49 %. Since these biomass burning figures contrast with the official emissions inventory of Mexico City metropolitan area, which assigns <1 % of total CO2 emissions to biomass burning, this study could exhibit the emissions inventory underestimation of this source, and thus, the need to reassess and incorporate top-down isotopic constraints in fire-affected urban regions.

Mexico↗

PubMed2005

Molecular characteristics of urban organic aerosols from Nanjing: a case study of A mega-city in China.

Over 90 organic species have been determined in fine aerosols (PM2.5) collected during the summer and winter in Nanjing, a typical mega-city in China, using gas chromatography-mass spectrometry. The organic compounds detected were apportioned to four emission sources (i.e., plant emission, fossil fuel combustion, biomass burning, and soil resuspension) and secondary oxidation products. The most abundant classes of compounds are fatty acids, followed by sugars, dicarboxylic acids excluding oxalic and malonic acids, and n-alkanes, while alcohols, polyols/polyacids and lignin/sterols are less abundant. Total amounts of the seven classes of compounds were on average 938 ng m(-3) in the summer and 1301 ng m(-3) in the winter, respectively, contributing 0.26-1.96% of particle mass (PM2.5). In the summer, n-alkanes were heavily enhanced by vegetation emissions with a maximum carbon number (Cmax) at C29, whereas they were dominated by emissions from fossil fuels combustion with a Cmax at C22/ C23 in the winter. Concentrations of unsaturated fatty acids were lower in the summer than in the winter, being consistent with enhanced photooxidation of unsaturated fatty acids in the summer. Concentrations of dicarboxylic acids for the summer aerosols were much higher in the daytime than in the nighttime, indicating increased photochemical production in the daytime. In the summer, plant emissions were the most significant source of organic aerosols, contributing more than 33% of total compound mass (TCM), followed by fossil fuel combustion or secondary oxidation. In contrast, fossil fuel combustion was the dominant source of winter organic aerosols, contributing more than 51% of TCM, followed by plant emissions and secondary oxidation products. The quantitative results on sugars and lignin pyrolysis products further suggested that biomass burning and soil resuspension are also significant sources of urban organic aerosols.

Aerosols↗

PubMed1979

Atmospheric CO2 consequences of heavy dependence on coal.

Accurate and regular measurements of the concentration of CO2 in the atmosphere during the past 20 years show an accelerating increase. Although clearing of tropical forests has released large amounts of carbon to the atmosphere, evidence is strong that a major contributor is the combustion of fossil fuels. Future energy demands of the world will require extensive further exploitation of fossil fuels, and projections show that without major development of nonfossil fuel alternatives, the atmospheric concentration will double within the next 75 years. Four issues require serious attention. The developing countries will require vastly increased amounts of energy. Major efforts to develop suitable (inexpensive) nonfossil energy sources to meet at least a portion of this demand are required. The distribution of carbon released from fossil fuels and from other anthropogenic sources among the reservoirs of the carbon cycle must be better defined. Uncertainties regarding the effect of the increased concentration of CO2 in the atmosphere on global climate must be reduced. Possible political and social responses to a substantial climate change must be studied in order to more fully understand all of the implication of increased atmospheric CO2.

Air Pollution↗

PubMed1977

Fertilizers for food production vs energy needs and environmental quality.

The world is experiencing an energy crisis that is restrictive to agricultural requisites production at the same time that food is becoming increasingly short on a global basis. Fertilizers are the most energy demanding of these inputs and have become very expensive and intermittently short in supply with the reduced availability of fossil fuels. They have been indicted, furthermore, as environmental pollutants due to their presumed role in eutrophication and in being a source of excessive NO3-N that may accumulate in some leaf crops and in drinking waters. Exponential growth in fossil fuel consumption cannot continue. Economies can be made in the agricultural sector, which does indeed consume substantial quantities of energy. The energy consumed in this very essential food-producing process, however, is almost insignificant compared with that involved in transport and processing of food beyond the farm and with other energy expenditures in modern society. A shift in priorities will certainly be required in adapting to the real world of the 1970s if man's first need is to be met. Economies in fertilizer use can be made by adherence to known agronomic principles. Savings in fossil fuel energy can probably be effected also in the production of N fertilizer, by far the most fossil-energy-demanding process in the realm of agriculture. Considerable research remains to be done, however, under varied climatic conditions for understanding and controlling processes by which residuals from fertilizers may become environmental pollutants. The various issues in this paper must be resolved promptly in consideration of the now-existing energy crisis and the imminent world food crisis.

Air Pollution↗

PubMed2002

Radiocarbon as a tool to apportion the sources of polycyclic aromatic hydrocarbons and black carbon in environmental samples.

To determine the relative inputs of polycyclic aromatic hydrocarbons (PAHs) and black carbon (BC) in environmental samples from the combustion of fossil fuels and biomass, we have developed two independent analytical methods for determining the 14C abundance of PAHs and BC. The 5730 yr half-life of 14C makes it an ideal tracer for identifying combustion products derived from fossil fuels (14C-free) versus those stemming from modern biomass (contemporary 14C). The 14C abundance of PAHs in several environmental Standard Reference Materials was measured by accelerator mass spectrometry after extraction and then purification by high-performance liquid chromatography and preparative capillary gas chromatography. This method yields pure compounds that allow for a high degree of confidence in the 14C results. The PAHs data were then used to compare and evaluate results from an operationally defined thermal oxidation method used to isolate a BC fraction. The 14C compositions of PAHs and BC were very similar and suggest that the thermal oxidation method employed for isolating BC is robust and free from interferences by non-BC components. In addition, these data indicate that both the PAHs and the BC species derive mostly from fossil fuels and/or their combustion products.

Biomass↗

PubMed1996

Assessing long-term impacts of increased crop productivity on atmospheric CO2.

A full assessment of the impacts of land clearance and crop production on atmospheric CO2 requires a systems approach. By considering long-term soil carbon changes and fossil fuel energy inputs, we show that increased crop productivity will alleviate CO2 release to the atmosphere primarily by preventing additional land cultivation. Each hectare of cropland undergoing a simulated threefold crop productivity increase here prevents a net release on the order of 150-200 Mg C to the atmosphere over 100 years by avoiding additional land cultivation which would otherwise be required. This effective carbon sink would slowly diminish with time due to fossil fuel energy input requirements. However, future self-containment of the energy needs of high-yield crop production may displace on the order of 1.0 Pg C per year of fossil fuel carbon, in addition to the carbon sink attributable to avoided land cultivation. By avoiding land cultivation, high yield crop systems also preserve natural ecosystems.

Agriculture↗

PubMed1993

Estimates of emissions of SO2, NOx, HCl and NH3 from a densely populated region of the UK.

Estimates of emissions of SO2, NOx, HCl and NH3 have been made for a densely populated region of the UK, the North-West of England, using data on power generation, incinerator plant capacity, fuel usage and animal and human population statistics. The spatial distributions of SO2 and NOx emissions are quite different, reflecting their different source strengths. The emissions from motor vehicles make up 52% of the NOx emissions from the North-West of England, whilst those from fossil-fuel-fired power stations make up 20%. The emissions of fossil-fuel-fired power stations make up 58% of SO2 emissions from the North-West. A large fossil-fuel-fired power station is the largest known point source for emissions of SO2, NOx and HCl. The largest contribution to NH3 emissions in the North-West is from cattle. Humans may contribute some NH3 to overall emissions but there is considerable uncertainty as to how much is emitted and what fraction of this is deposited within buildings. The uncertainties in the methodologies used are high-lighted and, where possible, recommendations are made as to how future emissions estimates might be improved. Potential reductions in emissions of SO2, NOx and HCl are discussed under basic scenarios of planned power station closures in the area and the compliance of the electricity generation industry with the European Community Directive on Large Combustion Plants.

Journal Article↗

PubMed2006

Comparing primary energy attributed to renewable energy with primary energy equivalent to determine carbon abatement in a national context.

The current conventional approach to determining the primary energy associated with non-combustible renewable energy (RE) sources such as wind energy and hydro power is to equate the electricity generated from these sources with the primary energy supply. This paper compares this with an approach that was formerly used by the IEA, in which the primary energy equivalent attributed to renewable energy was equated with the fossil fuel energy it displaces. Difficulties with implementing this approach in a meaningful way for international comparisons lead to most international organisations abandoning the primary energy equivalent methodology. It has recently re-emerged in prominence however, as efforts grow to develop baseline procedures for quantifying the greenhouse gas (GHG) emissions avoided by renewable energy within the context of the Kyoto Protocol credit trading mechanisms. This paper discusses the primary energy equivalent approach and in particular the distinctions between displacing fossil fuel energy in existing plant or in new plant. The approach is then extended provide insight into future primary energy displacement by renewable energy and to quantify the amount of CO2 emissions avoided by renewable energy. The usefulness of this approach in quantifying the benefits of renewable energy is also discussed in an energy policy context, with regard to increasing security of energy supply as well as reducing energy-related GHG (and other) emissions. The approach is applied in a national context and Ireland is case study country selected for this research. The choice of Ireland is interesting in two respects. The first relates to the high proportion of electricity only fossil fuel plants in Ireland resulting in a significant variation between primary energy and primary energy equivalent. The second concerns Ireland's poor performance to date in limiting GHG emissions in line with its Kyoto target and points to the need for techniques to quantify the potential contribution of renewable energy in achieving the target set.

Carbon↗

PubMed1982

Possible future trends of radiation exposure by carbon 14.

The possible future trends of the radiation exposure by carbon 14 have been assessed. The individual lifetime doses and the European and global dose commitments were calculated by a specific activity model. A non-linear compartment model was developed so simulate the global cycling of carbon dioxide from the combustion of fossil fuels and of radiocarbon released from nuclear energy facilities until the year 2200. The energy scenarios considered are: (I) logistic growth functions for energy supply with fossil fuels; (II) a high, low and moderate estimate for the extension of nuclear energy (light water reactors). In addition, the influence of the retention of C-14 in the fuel reprocessing plant effluents was tested. For most of the scenarios considered the increase of the specific activity by C-14 releases is more than compensated by the CO2 releases from fossil fuels. Up to 2200 individual lifetime dose commitments for 70 years were found between 0.85 and 0.45 mSv (pre-industrial value: 0.73 mSv). The anthropogenic contributions to the global collective dose commitments until the year 2100 were estimated (for the moderate scenario without retention) at 1.27 X 10(6) man-Sv (11%) from nuclear weapon tests, 3.5 X 10(5) man-Sv (3%) from nuclear power plants, and 6.5 X 10(5) man-Sv (5.6%) from fuel reprocessing facilities.

Carbon Radioisotopes↗

PubMed2003

Greenhouse gas production in wastewater treatment: process selection is the major factor.

Many practical design and operating decisions on wastewater treatment plants can have significant impacts on the overall environmental performance, in particular the greenhouse gas (GHG) emissions. The main factor in this regard is the use of aerobic or anaerobic treatment technology. This paper compares the GHG production of a number of case studies with aerobic or anaerobic main and sludge treatment of domestic wastewater and also looks at the energy balances and economics. This comparison demonstrates that major advantages can be gained by using primarily anaerobic processes as it is possible to largely eliminate any net energy input to the process, and therefore the production of GHG from fossil fuels. This is achieved by converting the energy of the incoming wastewater pollutants to methane which is then used to generate electricity. This is sufficient to power the aerobic processes as well as the mixing etc. of the anaerobic stages. In terms of GHG production, the total output (in CO2 equivalents) can be reduced from 2.4 kg CO2/kg COD(removed) for fully aerobic treatment to 1.0 kg CO2/kg COD(removed) for primarily anaerobic processes. All of the CO2 produced in the anaerobic processes comes from the wastewater pollutants and is therefore greenhouse gas neutral, whereas up to 1.4 kg CO2/kg COD(removed) originates from power generation for the fully aerobic process. This means that considerably more CO2 is produced in power generation than in the actual treatment process, and all of this is typically from fossil fuels, whereas the energy from the wastewater pollutants comes primarily from renewable energy sources, namely agricultural products. Even a change from anaerobic to aerobic sludge treatment processes (for the same aerobic main process) has a massive impact on the CO2 production from fossil fuels. An additional 0.8 kg CO2/kg COD(removed) is produced by changing to aerobic sludge digestion, which equates for a typical 100,000 EP plant to an additional production of over 10 t CO2 per day. Preliminary cost estimates confirm that the largely anaerobic process option is a fully competitive alternative to the mainly aerobic processes used, while achieving the same effluent quality.

Bacteria, Aerobic↗

PubMed1992

Chemical and radiological risk factors associated with waste from energy production.

We have tried to estimate the toxic potential of waste from nuclear power plants and from power plants burning fossil fuels. The potential risks have been expressed as 'risk potentials' or 'person equivalents.' These are purely theoretical units and represent only an attempt to quantify the potential impact of different sources and substances on human health. Existing concentration limits for effects on human health are used. The philosophy behind establishing limits for several carcinogenic chemicals is based on a linear dose-effect curve. That is, no lower concentration of no effect exists and one has to accept a certain small risk by accepting the concentration limit. This is in line with the establishment of limits for radiation. Waste products from coal combustion have the highest potential risk among the fossil fuel alternatives. The highest risk is caused by metals, and the fly ash represents the effluent stream giving the largest contribution to the potential risk. The waste from nuclear power production has a lower potential risk than coal if today's limit values re used. If one adjusts the limits for radiation dose and the concentration limit values so that a similar risk is accepted by the limits, nuclear waste seems to have a much higher potential risk than waste from fossil fuel. The possibility that such risk estimates may be used as arguments for safe storage of the different types of waste is discussed. In order to obtain the actual risk from the potential risk, the dispersion of the waste in the environment and its uptake and effects in man have to be taken into account.

Environmental Pollution↗

PubMed1996

Global increases in allergic respiratory disease: the possible role of diesel exhaust particles.

OBJECTIVE: Reading this article will enable the readers to recognize and evaluate i e potential relationship between allergic respiratory disease and polyaromatic hydrocarbons as air pollutants from industrial and automotive fuel sources. In this article we review the long-term trends in the prevalence of allergic airway diseases (rhinitis and asthma). We then examine the epidemiologic and other research data relating to the role that hydrocarbon fuel emissions may have had on allergic respiratory disease. DESIGN: Published literature on the relationship between specific air pollutants and trends in allergic respiratory disease were reviewed. Reports of research on pollutant effects on allergic antibody (IgE) were also studied. In both cases, the Melvyl-Medline database since 1975 was used for literature searches. Older references were identified from the bibliographies of relevant articles and books and with the help of the rare books collection at UCLA's Louis M. Darling Biomedical library. RESULTS: Examination of the historical record indicates that allergic rhinitis and allergic asthma have significantly increased in prevalence over the past two centuries. Although the reasons for this increase are not fully elucidated, epidemiologic data suggest that certain pollutants such as those produced from the burning of fossil fuels may have played an important role in the prevalence changes. Also important are studies showing that diesel exhaust, a prototypical fossil fuel, is able to enhance in vitro and in vivo IgE production. CONCLUSION: Increased levels of the compounds resulting from fossil fuel combustion may be partly responsible for the increased prevalence of allergic respiratory disease. If the nature of these compounds and the mechanisms by which they exacerbate allergic disease can be identified, steps can be taken to reduce the production or the impact of these allergy producing compounds.

Humans↗

PubMed1983

Community and occupational studies of lung cancer and polycyclic organic matter.

Finland is used as a model in attempts to study the possible association of the incidence of lung cancer and exposure of population to fossil fuel combustion products. Unfortunately because of great geographical variation of unknown origin in the incidence of lung cancer in Finland, detailed studies of the possible role of an individual exposure in the lung cancer risk are not possible. This background variation in the incidence is much greater than variation carried by any known etiological factor and does not clearly correlate with the degree of urbanization, industrialization, regional use of fossil fuels, number of motor vehicles or smoking habits. To get more precise information on the possible association of lung cancer incidence with exposure to fossil fuel combustion products, occupational studies serve as powerful tools. The definition of population is more reliable and the measurement of exposures can be done more precisely; moreover the management of confounding and modifying factors is more effective than in community studies. So far the studies carried out among the Finnish working population exposed to PAH compounds reveal an association between the lung cancer risk and exposure to PAHs.

Adult↗

PubMed2005

Contribution of biomass burning to atmospheric polycyclic aromatic hydrocarbons at three European background sites.

Radiocarbon analysis of atmospheric polycyclic aromatic hydrocarbons (PAHs) from three background areas in Sweden, Croatia, and Greece was performed to apportion their origin between fossil and biomass combustion. Diagnostic ratios of PAHs implied that wood and coal combustion was relatively more important in the northern European site, while combustion of fossil fuels was the dominant source of PAHs to the two central-southern European background sites. The radiocarbon content (delta14C) of atmospheric PAHs in Sweden ranged between -388 per thousand and -381 per thousand, while more depleted values were observed for Greece (-914 per thousand) and Croatia (-888 per thousand). Using a 14C isotopic mass balance model it was calculated that biomass burning contributes nearly 10% of the total PAH burden in the studied southern European atmosphere with fossil fuel combustion making up the 90% balance. In contrast, biomass burning contributes about 50% of total PAHs in the atmosphere at the Swedish site. Our results suggest that the relative contributions of biomass burning and fossil fuels to atmospheric PAHs may differ considerably between countries, and therefore, different national control strategies might be needed if a further reduction of these pollutants is to be achieved on a continental-global scale.

Air Pollutants↗

PubMed2000

The meaning of air quality and flue gas emission standards for public acceptance of new thermal power plants.

For the time being only 30-40% of the electric energy supply in Croatia comes from burning fossil fuel. New capacities of 800-1400 MW for the next decade will have to rely on the exclusive use of fossil fuels in thermal power plants (TPP). Public opinion will probably have a decisive influence on the issuing of construction permissions. The potential adverse effects on air seem to be the main argument against construction of TPPs. The priority is therefore to unambiguously state what air quality is warranted in the influenced area for the whole operation period of a TPP. It is important that the public should understand the real meaning of current air quality standards and emission limits. The only known way to do it today is through comparison with the corresponding standards and limits accepted worldwide. This paper discusses some important aspects of such comparison.

Air Pollutants↗

PubMed2006

Assessment of atmospheric deposition of heavy metals and other elements in Belgrade using the moss biomonitoring technique and neutron activation analysis.

This study aimed at assessing atmospheric deposition of heavy metals and other elements using the moss genera Brachythecium sp. (B. rutabulum and B. salebrosum) and Eurhynchium sp. (E. hians and E. striatum) collected in autumn 2004 in the urban area of Belgrade. The concentrations of 36 elements (Na, Mg, Al, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Br, Rb, Sr, Mo, Sb, I, Cs, Ba, La, Ce, Sm, Tb, Dy, Hf, Ta, W, Hg, Th, U) were determined in moss and local topsoil samples by instrumental neutron activation analysis. The concentration of elements in moss positively correlated to those obtained for topsoil. High enrichment factors for As, Zn, Mo, Br, Sb, Se, Hg and Cl, calculated to continental crust composition, gave an evidence for anthropogenic impact on urban area, mainly due to intensive vehicular traffic and fossil fuel combustion. The concentration of elements in moss, characteristic for fossil fuel combustion, obtained in this study were substantially lower than in the previous investigation (2000) conducted in the area of Belgrade. The level of concentrations for V, Cr, Ni, and As in moss from this study correlated to those measured for neighboring countries, and were several times higher than the base-level data from low polluted areas. The level of accumulated elements in both investigated moss genera were similar and all studied species could be combined for biomonitoring purposes in urban areas.

Air Pollutants↗

PubMed2005

A greenhouse gas emissions inventory for Pennsylvania.

The Pennsylvania greenhouse gas (GHG) emissions inventory presented in this paper provides detailed estimates of emissions and their sources for the six major categories of GHGs. The inventory was compiled using the current U.S. Environment Protection Agency methodology, which applies emissions factors to socioeconomic data, such as fossil energy use, vehicle miles traveled, and industrial production. The paper also contains an assessment of the methodology and suggestions for improving accounting with respect to process, sectoral, and geographic considerations. The study found that Pennsylvania emitted 77.4 million metric tons carbon equivalent of GHGs in 1990 and that this total increased by 3% to 79.8 million metric tons carbon equivalent by 1999. Despite this increase, however, the state's percentage contribution to the United States total declined during the decade. Pennsylvania's carbon dioxide (CO2) emissions from fossil fuels represented 92.4% of 1990 totals and declined to 90.5% in 1999. Electricity generation was the largest single source of CO2 emissions, being responsible for 38% of fossil fuel CO2 emissions in 1990 and 40% of the total in 1999. Transportation emissions accounted for the largest increases in emissions between 1990 and 1999, whereas industrial emissions accounted for the largest decrease. The overall trend indicates that Pennsylvania has been able to weaken the relationship between GHG emissions and economic growth.

Agriculture↗

PubMed2004

Energy intensity of computer manufacturing: hybrid assessment combining process and economic input-output methods.

The total energy and fossil fuels used in producing a desktop computer with 17-in. CRT monitor are estimated at 6400 megajoules (MJ) and 260 kg, respectively. This indicates that computer manufacturing is energy intensive: the ratio of fossil fuel use to product weight is 11, an order of magnitude larger than the factor of 1-2 for many other manufactured goods. This high energy intensity of manufacturing, combined with rapid turnover in computers, results in an annual life cycle energy burden that is surprisingly high: about 2600 MJ per year, 1.3 times that of a refrigerator. In contrast with many home appliances, life cycle energy use of a computer is dominated by production (81%) as opposed to operation (19%). Extension of usable lifespan (e.g. by reselling or upgrading) is thus a promising approach to mitigating energy impacts as well as other environmental burdens associated with manufacturing and disposal.

Computers↗