This study analyzes the potential to reduce air pollutants while achieving the 2 °C global temperature change limit target above pre-industrial levels, by using the bottom-up optimization model, AIM/Enduse[Global]. This study focuses on; 1) estimating mitigation potentials and costs for achieving 2 °C, 2.5 °C, and 3 °C target scenarios, 2) assessing co-benefits of reducing air pollutants such as NOx, SO2, BC, PM, and 3) analyzing features of sectoral attributions in Annex I and Non-Annex I groups of countries. The carbon tax scenario at 50 US$/tCO2-eq in 2050 can reduce GHG emissions more than the 3 °C target scenario, but a higher carbon price around 400 US$/tCO2-eq in 2050 is required to achieve the 2 °C target scenario. However, there is also a co-benefit of large reduction potential of air pollutants, in the range of 60–80% reductions in 2050 from the reference scenario while achieving the 2 °C target.

Metro rail has been introduced in Delhi in 2002 to provide alternative mode of public transportation. The introduction of metro rail has resulted in passenger ridership shift from road based transport to metro rail. In order to estimate the emissions (CO, HC, NOx, PM and CO2), metro rail ridership has been converted to equivalent number of on–road vehicles which otherwise would have been playing in the absence of mass rapid transit system. The emission estimation for the year 2006 and 2011 corresponding to the completion of phase I and phase II of Delhi metro rail has been made using emission and deterioration factor(s) for different category and vintage of vehicles. The sensitivity analysis has been carried out to assess the influence of different combination of input parameters such as modal shift, engine technology, and fuel type on emissions. In addition, CO2 emissions saved due to shifting of motor vehicle ridership to metro rail has been estimated and compared with the CO2 produced (off–site) due to electricity consumption by Delhi metro rail for its various operations. The findings indicate that present modal shift scenario does not yield CO2 benefits. However, it is expected that with the increase in metro ridership, changes in modal shift and energy conservation initiatives by Delhi metro, CO2 emission saving could be possible.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy).This article has been retracted at the request of the Editor-in-Chief and the Authors.This paper has to be retracted as the authors have noticed a procedural error with regards to their data which affects the results and discussion of the paper. It is important to note that this is not considered to be the result of scientific misconduct, but rather honest errors by the authors.

Fugitive greenhouse gas emissions from unconventional gas extraction processes (e.g. shale gas, tight gas and coal bed methane/coal seam gas) are poorly understood due in part to the extensive area over which these emissions may occur. We apply a rapid qualitative approach for source assessment at the scale of a large gas field. A mobile cavity ring down spectrometer (Picarro G2201-i) was used to provide real-time, high-precision methane and carbon dioxide concentration and carbon isotope ratios (δ¹³C), allowing for “on the fly” decision making and therefore an efficient and dynamic surveying approach. The system was used to map the atmosphere of a production coal seam gas (CSG) field (Tara region, Australia), an area containing pre-production “exploration” CSG wells (Casino, Australia), and various other potential CO₂and CH₄sources (i.e. wetlands, sewage treatment plants, landfills, urban areas and bushfires). Results showed a widespread enrichment of both CH₄(up to 6.89 ppm) and CO₂(up to 541 ppm) within the production gas field, compared to outside. The CH₄and CO₂δ¹³C source values showed distinct differences within and outside the production field, indicating a CH₄source within the production field that has a δ¹³C signature comparable to the regional CSG. While this study demonstrates how the method can be used to qualitatively assess the location and source of emissions, integration with atmospheric models may allow for quantitative assessment of emissions. The distinct patterns observed within the CSG field demonstrates the need to fully quantify the atmospheric flux of natural and anthropogenic, point and diffuse sources of greenhouse gases from individual Australian gas fields before and after production commences.

In order to assess correctly the gases emissions from oil/gas field water and its contributions to the source of greenhouse gases (GHG) at the atmospheric temperature and pressure, a simulation experiment was first developed to study the natural emissions of GHG into the atmosphere in the southern gas field, Sichuan Basin, China. The result showed that methane (CH₄) and carbon dioxide (CO₂) were the two gases that released from the gas field water. Time and temperature played important roles in GHG emissions, and the higher temperature was found to enhance carbon emissions. Under the lower/intermediate temperature conditions (5 and 15 °C), majority of gases were released from the gas field water during the first 2 h, whereas under the higher temperature conditions (30 °C), the majority of gas released from the gas field water continued for 12 h. By dividing the whole emission duration into six time durations (one time duration was 12 h), we calculated the fluxes of CH₄and CO₂. The substantial variation in the gas fluxes reflected that the cumulation of time also played a crucial role in the process of GHG emissions. In the first emission duration (0–12 h) at 30 °C, the maximum fluxes of CH₄and CO₂were 1.47 and 1.87 g/m³·h, respectively. The values were obviously higher than those in other durations, so were the fluxes shift in different durations at 5 and 15 °C. Additionally, we found that the emissions released from the gas field water which came from overpressure formation formed higher carbon emissions.

Methane (CH₄) formation in wastewater treatment is linked to long residence times under anaerobic conditions such as those in sewers and primary treatment units. Emissions of this methane to the atmosphere can occur under turbulent flows and, potentially, during aeration in an activated sludge plant. An online, 8-week monitoring campaign of CH₄emissions and operational conditions was conducted to study emissions from a full-scale nitrifying activated sludge plant (ASP). Significant emissions were found throughout the aerated lane, with the highest values observed two thirds down the lane. Emissions had high diurnal and spatial variability, with values ranging from 0.3 to 24 g CH₄/h. No significant correlations were found between dissolved oxygen, aeration or influent loads. The results suggest that emissions are linked to upstream process conditions, with potential for methane generation in-lane due periods of limited oxygen availability. The dynamic oxygen profile observed suggests that aerobic and anoxic conditions coexist in the lane, leading to limited oxygen diffusion from the bulk liquid to the inner regions of the floc where anoxic/anaerobic layers may allow methanogenic microorganisms to survive. The average emission factor was 0.07 % of removed chemical oxygen demand, giving a total of 668 kg CH₄/year and 14,000 CO₂equivalents/year. The operational carbon associated with the energy requirements of the ASP increased by 5 %. With emerging legislation requiring the reporting of greenhouse gas emissions, the carbon impact may be significant, particularly as the industry moves towards a carbon-reducing future. Therefore, an adequate profiling of full-scale emissions is critical for future proofing existing treatment technologies.

A 3-year study was conducted to determine the effects of anaerobic digestion (AD), large particle solids, and manure additive (More Than Manure, MTM™) on ammonia (NH₃) and greenhouse gas (GHG; carbon dioxide, nitrous oxide, and methane) emissions when raw and treated manure were surface-applied. The presence of large particle solids resulted in greater NH₃ emissions, probably, due to reduced infiltration of liquid manure into soil (P < 0.05). Anaerobic digestion did not have a consistent effect on NH₃ emission. Manure with greater ammoniacal nitrogen (AN) concentrations had significantly greater NH₃ loss after manure application (P < 0.05). Anaerobic digestion of manure also did not have a significant effect on GHG flux (P > 0.05). Raw manure with large particle solids had significantly greater CO₂ flux than the other raw manure treatments on the day of manure application (P < 0.05). There was no significant manure treatment effects (P > 0.2) on methane flux over the 3-day period after manure application. The manure additive MTM™ did not have significant effects (P > 0.05) on NH₃ and GHG fluxes. The results of this study suggest that solids and AN concentrations in manure are the most important factors affecting NH₃ emissions after surface application.

The objective of the study is to empirically examine the air pollution, greenhouse gas (GHG) emissions and low birth weight in Pakistan through the cointegration and error correction model over a 36-year time period, i.e., between 1975 and 2012. The study employed the Johansen cointegration technique to estimate the long-run relationship between the variables, while an error correction model was used to determine the short-run dynamics of the system. The study was limited to the following variables, including carbon dioxide emissions, methane emissions, nitrous oxide emissions, GHG emissions, and low birth weight in order to manage robust data analysis. The results reveal that air pollution and GHG emissions significantly affects the low birth weight in Pakistan. In the long run, carbon dioxide emissions act as a strong contributor for low birth weight, as the coefficient value indicates there is a more elastic relationship (i.e., −1.214, p < 0.000) between them, whereas in the short run, this results has been evaporated. Subsequently, in the short run, GHG emissions have a one-to-one corresponding relationship with the low birth weight in Pakistan. Nitrous oxide emissions, both in the short and long run, have a significant and less elastic relationship (i.e., −0.517 with p < 0.001 and −0.335 with p < 0.090). Methane emissions have no significant relationship with the low birth weight in Pakistan.

In this study, an environmental assessment on an electrokinetic (EK) system for the remediation of a multimetal-contaminated real site was conducted using a green and sustainable remediation (GSR) tool. The entire EK process was classified into major four phases consisting of remedial investigations (RIs), remedial action construction (RAC), remedial action operation (RAO), and long-term monitoring (LTM) for environmental assessment. The environmental footprints, including greenhouse gas (GHG) emissions, total energy used, air emissions of criteria pollutants, such as NOₓ, SOₓ, and PM₁₀, and water consumption, were calculated, and the relative contribution in each phase was analyzed in the environmental assessment. In the RAC phase, the relative contribution of the GHG emissions, total energy used, and PM₁₀emissions were 77.3, 67.6, and 70.4 %, respectively, which were higher than those of the other phases because the material consumption and equipment used for system construction were high. In the RAO phase, the relative contributions of water consumption and NOₓand SOₓemissions were 94.7, 85.2, and 91.0 %, respectively, which were higher than those of the other phases, because the water and electricity consumption required for system operation was high. In the RIs and LTM phases, the environmental footprints were negligible because the material and energy consumption was less. In conclusion, the consumable materials and electrical energy consumption might be very important for GSR in the EK remediation process, because the production of consumable materials and electrical energy consumption highly affects the GHG emissions, total energy used, and air emissions such as NOₓand SOₓ.

The objective of the study is to examine the long-run and causal relationship between climate change (i.e., greenhouse gas emissions, hydrofluorocarbons, per fluorocarbons, and sulfur hexafluoride), air pollution (i.e., methane emissions, nitrous oxide emissions, and carbon dioxide emissions), and tourism development indicators (i.e., international tourism receipts, international tourism expenditures, natural resource depletion, and net forest depletion) in the World’s largest regions. The aggregate data is used for robust analysis in the South Asia, the Middle East and North Africa, sub-Saharan Africa, and East Asia and the Pacific regions, over a period of 1975–2012. The results show that climatic factors and air pollution have a negative impact on tourism indicators in the form of deforestation and natural resource depletion. The impact is evident, as we have seen the systematic eroding of tourism industry, due to severe changes in climate and increasing strain of air pollution. There are several channels of cause–effect relationship between the climatic factors, air pollution, and tourism indicators in the World’s region. The study confirms the unidirectional, bidirectional, and causality independent relationship between climatic factors, air pollution, and tourism indicators in the World. It is conclusive that tourism industry is facing all time bigger challenges of reduce investment, less resources, and minor importance from the government agencies because of the two broad challenges, i.e., climate change and air pollution, putting them in a dismal state.