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1.
Sci Total Environ ; 704: 135375, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-31806299

RESUMO

The sustainable development of agriculture depends on increasing N use efficiency (NUE) and consequently reducing N losses from different sources, such as NH3 volatilization, NO3- leaching, and N2O emissions. While the chemical and physical properties of biochar (BC) in fertilizers have been evaluated to increase NUE, a lack of information exists regarding the effects of BC amendments in tropical soils. We performed a one-year field experiment with tropical soil to evaluate the effects of BC-based N fertilizers (BN) on maize yield and on greenhouse gas (GHG) emissions. The treatments consisted of five fertilizers: ammonium nitrate (AN), urea (U), BN51/10 (51% BC, 10% N), BN40/17 (40% BC, 17% N), BN29/20 (29% BC, 20% N), and a control (without N fertilizer). The N fertilizers (80 kg N ha-1) were broadcast 20 days after sowing. Yield, grain N uptake, NUE, ammonia volatilization, and GHG emissions were measured. The results demonstrated the potential of BNs to enhance the efficiency of the fertilizers. BN51/10 and BN40/17 had an average maize yield that was 26% higher than that of U, and BN51/10 resulted in a NUE that was 12% higher than what was observed for U. Both the effects on yield and NUE were attributed to lower N release rates of the BN-amended fertilizers compared to that of the conventional soluble N sources. The BC-based fertilizers presented better environmental performance, and BN51/10 showed the lowest emission intensity when C sequestration by BC was not considered, with a value that was 14% lower than that of the U treatment. When considering C sequestration by BC, the emission intensity of the C equivalents demonstrated that all BNs presented C sequestration that differed from that of the mineral N sources. BC-based nitrogen fertilizers may have promising applications for sustainable agricultural development by mitigating N losses and increasing C stocks.


Assuntos
Agricultura/métodos , Carvão Vegetal/química , Fertilizantes , Gases de Efeito Estufa/análise , Nitrogênio/análise , Solo/química , Zea mays
2.
Sci Total Environ ; 704: 135420, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-31812389

RESUMO

Agricultural practices can reduce emissions of greenhouse gases (GHG). The definition of management practices toward mitigating GHG emissions could gain accuracy by integrating critical values of soil variables related to GHG fluxes. The aim of this study was to combine critical values of soil variables determining groups of GHG fluxes with similar and/or opposite direction of carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). We determined CO2, N2O, CH4 fluxes, soil temperature, gravimetric soil moisture (GSM), soil inorganic nitrogen (SIN), soil bulk density (SBD), soil porosity (P), and water-filled pore space (WFPS) monthly in three consecutive growing seasons in a sugarcane agroecosystem. The regression tree method defined groups of emission. Six terminal groups of CO2, N2O fluxes, and four for CH4 fluxes were determined. The critical values of soil variables that defined the terminal groups with the highest fluxes were soil temperature (>19 °C) and GSM (>35.2%) for CO2, GSM (>29.2%) and SIN (≤1.1 ppm) for N2O, and GSM (>24.9 °C), SBD (>0.98 g cm-3) and SIN (>1.82 ppm) for CH4. Trade-offs were found among GHGs: N2O emissions were high and CO2 emissions were low when GSM and soil temperature ranged from 29 to 35% and 14-19 °C, respectively (moderate values). CO2 emissions were high and N2O emissions were the lowest when GSM was equal or lower than 29.2% and soil temperature ranged from 19 to 21.3 °C. In this study, we highlight that management practices aimed to mitigate GHG fluxes should consider the integrated analysis of critical values of soil variables for GHGs together in order to avoid trade-offs.


Assuntos
Agricultura/métodos , Poluição do Ar/prevenção & controle , Gases de Efeito Estufa/análise , Saccharum , Solo
3.
Chemosphere ; 239: 124795, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31520977

RESUMO

Greenhouse gas (GHG) emissions from constructed wetlands (CWs) have raised environmental concern and thus offset their environmental and ecological benefits. This study evaluated the influence of plant species, i.e., Canna indica (C. indica), Cyperus alternifolius (C. alternifolius), Phragmites australis (P. australis) and unplanted control, on GHG emissions, pollutant removal and associated microbial abundance in subsurface flow constructed wetland (SSFCW) mesocosms. C. indica outperformed the other tested plant species in pollutant removal, and the presence of plants irrespective of species enhanced the removal efficiencies of nitrogen, phosphorus and organics in SSFCW mesocosms compared to unplanted control. The greatest carbon dioxide (CO2) flux (582.01 ±â€¯89.25 mg/m2/h), methane (CH4) flux (21.88 ±â€¯2.51 µg/m2/h) and nitrous oxide (N2O) flux (37.27 ±â€¯15.82 µg/m2/h) were observed in mesocosms planted with C. indica, P. australis and C.alternifolius, respectively. Unexpectedly, the mcrA and pmoA genes were not detected in any mesocosms. For denitrifiers, the N2O fluxes showed a significantly (p < 0.05) positive correlation with nirS and nirK genes abundance. The abundance of nosZ gene (ranged from 0.18 × 104 to 0.75 × 104 copies/mg gravel) and nosZ/(nirS + nirK) (ranged from 1.29 × 10-4 to 2.12 × 10-4 copies/mg gravel) in this study was lower than that in most reported studies. Regarding the global warming potential (GWP), the lowest value was observed in mesocosms planted with C. indica. In conclusion, C. indica is selected as the optimal plant species in this study due to its lower GWP and excellent pollutant removal performance.


Assuntos
Gases de Efeito Estufa/análise , Magnoliopsida/fisiologia , Eliminação de Resíduos Líquidos/métodos , Áreas Alagadas , Dióxido de Carbono/análise , Desnitrificação , Metano/análise , Nitrogênio/metabolismo , Óxido Nitroso/análise , Fósforo/metabolismo , Especificidade da Espécie , Águas Residuárias/análise
4.
Sci Total Environ ; 699: 134231, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31677472

RESUMO

The improvement of diets from a nutritional and health perspective has been a critical policy objective in developing nations for the past few decades. However, the current stress that human populations are exerting on the planet has made it important to assess diets using environmental indicators, such as greenhouse gas (GHG) emissions. Therefore, the main objective of the current study was to propose a methodology in which Life Cycle Assessment results linked to dietary patterns in Peru were combined with nutritional and economic data to optimize diets. For this, a linear programming model was built in which the environmental, nutritional and economic information on a set of 25 dietary patterns in Peru were optimized in order to achieve the environmentally best-performing diet that complies with economic and nutritional standards. The result of the proposed linear program allowed understanding the amount of each individual food product that should be consumed in each city that satisfies all the restrictions included in the model in order to attain the lowest GHG emissions possible. Results demonstrated that GHG reductions in food diets can be attained through optimization. For instance, in the case of Lima the obtained reduction was 6%, lowering the annual per capita footprint linked to food diets to 690 kg CO2eq, as compared to the current value of 736 kg CO2eq. From an economic perspective, results show that there are important disparities between cities in terms of increasing or decreasing prices of the market basket. Considering that in most areas of the country food purchase accounts for approximately 50% of household expenditure, it is plausible to assume that food choice is a main carrier to achieve GHG emission mitigations. In this context, the method constitutes a useful tool for policy-makers to push forward joint regulations to improve health-related issues linked to the food diet and food choice together with recommendations to lower the climatic impact of diets.


Assuntos
Poluição do Ar/prevenção & controle , Dieta/métodos , Alimentos , Abastecimento de Alimentos , Gases de Efeito Estufa/análise , Humanos , Peru , Programação Linear
5.
Sci Total Environ ; 699: 134042, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31689667

RESUMO

Despite only occupying 5% of the worldwide arable area, fruit tree crops are of vital economic importance in many regions. Intensive cropping practices can lead to greenhouse gas (GHG) emissions. In order to reduce these emissions, numerous studies have been made on lowering N inputs or applying nitrification inhibitors (NIs) which tend to maintain or even increase yield while reducing N leaching and nitrogenous emissions to the atmosphere. However, very few studies have been conducted on potential GHG emissions from the peach crop. In this work, a three-year study was carried out in a commercial peach orchard with a split-plot design with three replicates, in which the main factor was N dose (25, 50 and 100 kg N ha-1 year-1, and 50 kg N ha-1 year-1 applied during a shorter period of time in 2015 and 2016; and only 70 kg N ha-1 year-1 in 2017). Subplots in the study were used to analyse the effect of the application of a NI (3,4-dimethylpyrazole phosphate; DMPP). The aim was to qualitatively compare the effect of these factors on N2O, N2O + N2, CH4 and CO2 emissions from a peach orchard soil in order to recommend agricultural practices that minimise emissions without concurrent yield reductions. We show that N2O and N2O + N2 emissions were linked to fertilisation and increased with N dose. The N2O emissions were mitigated (up to 49%) by DMPP up to the 50 kg N ha-1 dose (not significantly). It seems that between 70 and 100 kg N ha-1 the application of DMPP loses effectiveness. Methane oxidation increased with N dose and decreased with DMPP application; CO2 emissions increased with DMPP and were unaffected by N dose. The intermediate N dose (50 kg N ha-1) applied during a shorter period of time increased yield (not significantly) and NUE without increasing GHG emissions.


Assuntos
Monitoramento Ambiental , Fertilizantes , Gases de Efeito Estufa/análise , Prunus persica , Agricultura , Produtos Agrícolas , Nitrificação , Nitrogênio/análise
6.
Environ Monit Assess ; 192(1): 63, 2019 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-31867682

RESUMO

This paper analyzes the building process of the main greenhouse gas (GHG) emissions (CO2, CH4 and N2O) inventory from the energy sector in Palestine. The paper includes determination tools, i.e., emission factors, to estimate the amounts of national GHG emissions from sub-sectors of energy including energy industries, manufacturing industries and construction, transport and other sectors (households, agriculture and commerce and public services). The results show that the total amount of national GHG emissions from the energy sector in 2016 was 4131 thousand metric tons of CO2-equivalent (TtCO2e), which represented 0.011% of the total global GHG emissions. The average value of GHG emissions per capita from the energy sector was 0.86 tCO2e in Palestine, and its gross domestic product was estimated at 3212 $/ton of CO2e. The estimated amounts of CO2, CH4 and N2O emission from the energy sector were 4022, 49 and 60 TtCO2e, respectively. The transport and household sub-sectors dominated the national GHG emissions from the entire energy sector by 58 and 32%, respectively. In general, fuels including diesel, gasoline, wood and charcoal and liquefied petroleum gas made most of the total amount of the national GHG emissions from the energy sector at 50, 18, 18 and 12%, respectively. Finally, the mitigation actions included in the first nationally determined contribution of Palestine and recommendations to help lower the national GHG emissions from the Palestinian energy sector are provided.


Assuntos
Fontes Geradoras de Energia/normas , Monitoramento Ambiental/métodos , Efeito Estufa/prevenção & controle , Gases de Efeito Estufa/análise , Agricultura , Carvão Vegetal/análise , Indústrias , Oriente Médio , Petróleo/análise , Madeira/química
8.
Sci Total Environ ; 694: 133699, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31756825

RESUMO

This paper investigates the full seasonal greenhouse gas (GHG) dynamics of fluxes from three green roof systems (lightweight clay aggregate-based green roof - LR; grass roof - GR; sod roof - SR) and natural control site on shallow Leptosol (NC), using closed static chambers in the period April 2014 to December 2015. CO2, CH4 and N2O fluxes are measured and their relationships to meteorological parameters and substrate physicochemical characteristics are quantified. Median CO2 flux values were 21 (LR), 38 (GR), 62 (SR), and 82 (NC) mg CO2-C m-2 h-1. The results show ecosystem respiration (Reco) clearly increased until July and then decreased until November. Net ecosystem CO2 exchange (NEE) was more variable than Reco, depending on plant growth phase and weather conditions. Median NEE values for study period (from April to November 2015) were -7 (LR), -17 (GR), -136 (SR), and -82 (NC) mg CO2-C m-2 h-1. The percentage of autotrophic respiration (Ra) in Reco showed clear rise from LR (35%) to NC (62%). CH4 consumption dominated resulting in median fluxes as follows: -2 (LR), -1 (GR), -15 (SR), and -23 (NC) µg CH4-C m-2 h-1. N2O flux was low and highly variable in time, with median values varying from -0.07 (GR) to 2.18 (NC) µg N2O-N m-2 h-1. During the maximum vegetation growth, NEE exceeded Reco value. Green roofs are effective CH4 sinks, but they do not significantly affect N2O flux. The main environmental factors determining GHG fluxes in linear models were parameters describing moisture regime, meteorological parameters and soil physical characteristics. These models can be used to predict GHG fluxes from similar green roof systems in analogous climatic conditions. We conclude that green roof technology may be used to mitigate excessive ambient GHG levels in urban areas.


Assuntos
Monitoramento Ambiental , Gases de Efeito Estufa/análise , Desenvolvimento Sustentável
9.
Environ Sci Pollut Res Int ; 26(36): 36845-36856, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31745796

RESUMO

This study investigated the impact of adding zeolite (F), superphosphate (G), and ferrous sulfate (L) in various combinations on reducing greenhouse gas (GHG) emission and improving nitrogen conservation during factory-scale chicken manure composting, aimed to identify the combination that optimizes the performance of the process. Chicken manure was mixed with F, G, FL, or FGL and subjected to windrow composting for 46 days. Results showed that global warming potential (GWP) was reduced by 21.9% (F), 22.8% (FL), 36.1% (G), and 39.3% (FGL). Further, the nitrogen content in the final composting product increased by 27.25%, 9.45%, and 21.86% in G, FL, and FGL amendments, respectively. The fertilizer efficiency of the compost product was assessed by measuring the biomass of plants grown in it, and it was consistent with the nitrogen content. N2O emission was negligible during composting, and 98% of the released GHGs comprised CO2 and CH4. Reduction in GHG emission was mainly achieved by reducing CH4 emission. The addition of FL, G, and FGL caused a clear shift in the abundance of dominant methanogens; particularly, the abundance of Methanobrevibacter decreased and that of Methanobacterium and Methanocella increased, which was correlated with CH4 emissions. Meanwhile, the changes in moisture content, NH4+-N content, and pH level also played an important role in the reduction of GHG emission. Based on the effects of nitrogen conservation, fertilizer efficiency improvement, and GHG emission reduction, we conclude that G and FGL are more beneficial than F or FL and suggest these additives for efficient chicken manure composting.


Assuntos
Compostagem , Difosfatos/química , Fertilizantes/análise , Gases de Efeito Estufa/análise , Esterco , Zeolitas/química , Animais , Galinhas , Aquecimento Global , Metano/análise , Nitrogênio/análise , Óxido Nitroso/análise , Solo
10.
Sci Total Environ ; 688: 1193-1204, 2019 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-31726550

RESUMO

Tropical peatlands are globally important source of greenhouse gases to the atmosphere, but data on carbon fluxes from these ecosystems is limited due to the logistical challenges of measuring gas fluxes in these ecosystems. Proposals to overcome the difficulties of measuring gas carbon fluxes in the tropics include remote sensing (top-down) approaches. However, these require information on the effect of vegetation communities on carbon dioxide (CO2) and methane (CH4) fluxes from the peat surface (bottom-up). Such information will help reducing the uncertainty in current carbon budgets and resolve inconsistencies between the top-down and bottom-up estimates of gas fluxes from tropical peatlands. We investigated temporal and spatial variability of CO2 and CH4 fluxes from tropical peatlands inhabited by two contrasting vegetation communities (i.e., mixed forest and palm swamp) in Panama. In addition, we explored the influence of peat chemistry and nutrient status (i.e., factorial nitrogen (N) and phosphorus (P) addition) on greenhouse gas fluxes from the peat surface. We found that: i) CO2 and CH4 fluxes were not significantly different between the two vegetation communities, but did vary temporally across an annual cycle; ii) precipitation rates and peat temperature were poor predictors of CO2 and CH4 fluxes; iii) nitrogen addition increased CH4 fluxes at the mixed forests when the water table was above the peat surface, but neither nitrogen nor phosphorus affected gas fluxes elsewhere; iv) gas fluxes varied significantly with the water table level, with CO2 flux being 80% greater at low water table, and CH4 fluxes being 81% higher with the water table above the surface. Taken together, our data suggested that water table is the most important control of greenhouse gas emissions from the peat surface in forested lowland tropical peatlands, and that neither the presence of distinct vegetation communities nor the addition of nutrients outweigh such control.


Assuntos
Ecossistema , Monitoramento Ambiental , Gases de Efeito Estufa/análise , Solo
11.
Environ Sci Pollut Res Int ; 26(32): 33702-33714, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31595410

RESUMO

In this study, we aimed at determining greenhouse gas (GHG) (CO2, CH4, and N2O) fluxes exchange between the soil collected from sites dominated by different vegetation types (Calamagrostis epigeios, Phragmites australis, and Carex schnimdtii) in nitrogenous loaded riparian wetland and the atmosphere. The intact soil columns collected from the wetland were incubated in laboratory and continuously treated with [Formula: see text]-enriched water simulating downward surface water percolating through the soil to become groundwater in a natural system. This study revealed that the soil collected from the site dominated by C. epigeios was net CO2 and N2O sources, whereas the soil from P. australis and C. schnimdtii were net sinks of CO2 and N2O, respectively. The soil from the site dominated by C. schnimdtii had the highest climate impact, as it had the highest global warming potential (GWP) compared with the other sites. Our study indicates that total organic carbon and [Formula: see text] concentration in the soil water has great influence on GHG fluxes. Carbon dioxide (CO2) and N2O fluxes were accelerated by the availability of higher [Formula: see text] concentration in soil water. On the other hand, higher [Formula: see text] concentration in soil water favors CH4 oxidation, hence the low CH4 production. Temporally, CO2 fluxes were relatively higher in the first 15 days and reduced gradually likely due to a decline in organic carbon. The finding of this study implies that higher [Formula: see text] concentration in wetland soil, caused by human activities, could increase N2O and CO2 emissions from the soil. This therefore stresses the importance of controls of [Formula: see text] leaching in the mitigation of anthropogenic N2O and CO2 emissions.


Assuntos
Monitoramento Ambiental , Gases de Efeito Estufa/análise , Nitratos/análise , Áreas Alagadas , Atmosfera , Dióxido de Carbono/análise , Clima , Aquecimento Global , Efeito Estufa , Água Subterrânea , Estudos Longitudinais , Metano/análise , Nitrogênio , Óxido Nitroso/análise , Poaceae , Solo
12.
Environ Monit Assess ; 191(10): 639, 2019 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-31529378

RESUMO

Although indispensable, significant uncertainty still exists in the underlying processes of the formation, dynamics, and emission of greenhouse gases (GHGs), the critical elements needed for the accurate estimation of greenhouse gas fluxes in inland lakes and reservoirs. Seasonal changes in water thermal stratification and turbulence strongly influence the concentration and emission of dissolved GHGs in water columns. Here, we studied the stratification and overturn processes of water column in the subtropical Lianhe Reservoir during different seasons and determined the dynamics of dissolved CO2, CH4, and N2O in the reservoir. Observation of temperature and analysis of chlorofluorocarbons (CFCs) clearly suggested that stratification of water column occurred in summer, but not in winter. The results showed that while dissolved oxygen (DO) was high in the top 5-m layer (the upper epilimnion layer), it dropped considerably especially below 10 m, resulting in an increase in concentration of CO2 and CH4. The high concentrations of dissolved N2O and CH4 were related to the decomposition of organic matter in the hypolimnion layer under anaerobic conditions after stratification. In winter overturn period, vertical circulants of water not only homogenized the concentration of DO in the water column, but also potentially moved CO2, CH4, and N2O from the bottom to the surface of the reservoir. The estimated GHG flux from the reservoir was - 7.13 mmol m-2 day-1 in summer and 2.14 mmol m-2 day-1 in winter. There was the potential that CO2 fluxes from subtropical lakes and reservoirs are overestimated by traditional geochemical models.


Assuntos
Monitoramento Ambiental/métodos , Gases de Efeito Estufa/análise , Oxigênio/análise , Água/análise , Dióxido de Carbono/análise , Lagos/análise , Estações do Ano
13.
Ying Yong Sheng Tai Xue Bao ; 30(9): 3126-3136, 2019 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-31529888

RESUMO

To understand the effects of different irrigation amounts on soil CO2, N2O, and CH4 emission characteristics and tomato yield, and further put forward effective reduction measures, we carried out an experiment with three irrigation levels: full irrigation (1.0W, W1.0; W meant irrigation amount needed to provide the adequate water), 20% deficit irrigation (0.8W, W0.8) and 40% deficit irrigation (0.6W, W0.6). We used static closed chamber and gas chromatography method to measure greenhouse gas emission in two consecutive greenhouse tomato rotation cycles from April to December, 2017. The results showed that cumulative soil CO2, N2O and CH4 emissions increased with increasing irrigation amounts in the two growing seasons (W1.0>W0.8>W0.6), and significant difference of N2O between W0.6 and W1.0 was observed, while other treatment effects on soil gas emissions were not obvious. Compared to W1.0, cumulative soil CO2 emissions were decreased by 12.2% and 8.3%, cumulative soil N2O emissions were decreased by 19.1% and 8.0%, and cumulative soil CH4 emissions were reduced by 11.0% and 6.2% for W0.6 and W0.8, respectively. Tomato yield and global warming potential of soil N2O and CH4 emissions (GWP) increased as irrigation amount increasing. Compared with W1.0, W0.6 significantly decreased tomato yield by 17.0% and GWP by 22.9%, while the difference between the effects of W0.8 and W1.0 on these two parameters was not significant. Global warming potential per tomato yield presented an increase then a decrease as irrigation amount increasing (W0.8>W1.0>W0.6), but without stanificance. Irrigation water use efficiency (IWUE) showed a decrease with increasing irrigation amount. Compared with W1.0, IWUE under W0.6 and W0.8 was increased by 38.3% and 9.4%, respectively. Soil CO2 flux was nega-tively and exponentially correlated with soil moisture. The dependence of soil CH4 flux on soil moisture showed a significantly positive correlation. An exponential negative correlation was observed between the soil N2O ux and soil temperature when soil temperature was below or above 18 ℃. Irrigation increased tomato yield and soil greenhouse gas emissions, but decreased IWUE. Therefore, W0.8 was the best mode of irrigation management when synthetically considering tomato yield, IWUE, and greenhouse effect.


Assuntos
Agricultura , Gases de Efeito Estufa/análise , Solo , Dióxido de Carbono/análise , Lycopersicon esculentum/crescimento & desenvolvimento , Metano/análise , Óxido Nitroso/análise
14.
Mar Pollut Bull ; 149: 110568, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31550579

RESUMO

This study used a self-developed a NDIR monitoring system to continuously monitor GHG emissions from a tidal constructed mangrove wetland at three typical habitats (mudflat, mangrove, and water surface) in four seasons. The NDIR monitoring system is able to explore the diurnal and seasonal variation of GHG emissions from the tidal constructed mangrove wetland and to estimate more precisely for the GHG emission based carbon budget of the wetland. The continuous monitoring technique is feasible and valuable for assessing the temporal variation of GHG uptake/emission to/from the wetland. Daytime CO2 emissions were always lower than those at nighttime due to photosynthesis process, while an opposite trend was observed for CH4 and N2O emissions. Seasonal variation of GHGs showed that the highest GHG emissions was observed in summer, and followed by fall, spring, and winter. For three typical habitats, mangrove emitted more amounts of GHGs than mudflat and water surface.


Assuntos
Sequestro de Carbono , Gases de Efeito Estufa/análise , Áreas Alagadas , Dióxido de Carbono/análise , Ecossistema , Metano/análise , Óxido Nitroso/análise , Estações do Ano , Taiwan
15.
Environ Sci Pollut Res Int ; 26(32): 32977-32992, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31512130

RESUMO

By employing China's provincial panel data covering period 2001-2016, the present study empirically investigates the impact of ICT on CO2 emission intensity. Specifically, this paper utilizes Internet penetration and mobile phone penetration as proxies to measure ICT respectively and employs quantile regression method to estimate the benchmark model at five quantiles (0.1, 0.25, 0.5, 0.75, and 0.9). It is demonstrated that Internet penetration at the national level has a significant negative effect on the CO2 emission intensity for all quantiles. In addition, Internet penetration has a significant negative effect on CO2 emission intensity at all quantiles except for 0.1 quantile for China's eastern provinces and has a significant negative effect on CO2 emission intensity at all quantiles for China's central provinces, whereas Internet penetration has no significant negative impact on CO2 emission intensity at all quantiles for China's western provinces. By comparison, the reduction effect of Internet penetration on CO2 emission intensity in China's eastern and central provinces is more obvious and in contrast with the reduction effect of Internet penetration on CO2 emission intensity in China's eastern provinces, it is greater in China's central provinces. Finally, the impact of mobile phone penetration on CO2 emission intensity is generally consistent with the impact of Internet penetration. This study provides further evidence that developing countries can simultaneously achieve economic development and reduce carbon emissions through ICT.


Assuntos
Dióxido de Carbono/análise , Tecnologia da Informação , Uso do Telefone Celular/estatística & dados numéricos , China , Desenvolvimento Econômico , Gases de Efeito Estufa/análise , Tecnologia da Informação/estatística & dados numéricos , Internet/estatística & dados numéricos , Análise de Regressão
16.
Environ Sci Pollut Res Int ; 26(32): 33416-33426, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31522393

RESUMO

Fluxes of methane (CH4) and nitrous oxide (N2O) from two rice varieties, Huayou 14 and Hanyou 8, were monitored using closed chamber/gas chromatography method. Huayou 14 is a commonly grown variety of rice whereas Hanyou 8 is a water-saving and drought-resistant rice (WDR) variety. Low soil volumetric water content (VWC) existed in the treatments on the slope (W5 < W4 < W3 < W2). On the slope, rice yields of Hanyou 8 decreased by 12-39%, and Huayou 14 by 11-46% as compared to the plots on the flat. The total compatible solutes in Hanyou 8 had a greater variational range than Huayou 14. Compared to W1, CH4 emissions from W2-W5 decreased by 58-86% in Hanyou 8 and 38-86% in Huayou 14, whereas those of N2O increased by 26-121% in Hanyou 8 and 49-189% in Huayou 14 across both two seasons, which was mainly because the VWC varied in W2-W5 treatment. Under the treatments in the slope (W2, W3, W4, and W5), the global warming potential (GWP) was dominated by N2O emissions, which accounted for 69-90% of the GWP. Hanyou 8 had greater tolerance for water stress than Huayou 14 did, as evident from the smaller reductions in rice yield and greater variational range of total compatible solutes content. Water stress could reduce CH4 emissions but decrease N2O emissions for both rice varieties. This results suggest that planting WDR varieties under water shortage irrigation (such as W4, W5) will be able to maintain rice yields and reduce the GWP with less water.


Assuntos
Agricultura/estatística & dados numéricos , Gases de Efeito Estufa/análise , Oryza , Agricultura/métodos , China , Secas , Aquecimento Global , Efeito Estufa , Metano/análise , Óxido Nitroso/análise , Estações do Ano , Solo/química
17.
Sci Total Environ ; 692: 1165-1174, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31539948

RESUMO

The management system of soils and nitrogen application can cause impacts on the N2O emissions produced by the agricultural sector. In the establishment of practices of greenhouse gas mitigation for this sector, the objective of this study was to evaluate the effect of soil tillage, with and without N fertilization, on N2O emissions from Oxisols under rainfed maize in the Brazilian Cerrado region. The managements were of monoculture maize under conventional tillage (CT) and no-tillage (NT), with (1) and without (0) application of N fertilizer (0 and 257 kg N ha-1). From November 2014 to October 2015, gas emissions were measured. The soil and climate variables were measured and related to the N2O fluxes. In the N-fertilized treatments, N2O fluxes were higher (P < 0.01), ranging from -21 µg m-2 h-1 to 548 µg m-2 h-1 N2O under conventional tillage and from -21 µg m-2 h-1 to 380 µg m-2 h-1 N2O under no-tillage, compared with -6 to 93 µg m-2 h-1 N2O from systems without N application. There was a combined effect of mineral N and water-filled pore space for most N2O fluxes. The emission factors of N2O during maize cultivation were lower than the standard factor (1%) established by the International Panel of Climate Change. During the plant crop cycle, 30% less N2O was emitted from the N-fertilized no-tillage than from the conventional tillage. For the total cumulative N2O (crop cycle + fallow), the N2O emissions from NT1 and CT1 were not different, but 10× higher than those from the respective crops without N fertilization. To the emissions per unit of grain yield, CT1 and NT1 emitted 769 and 391 mg N2O kg-1 grain produced, respectively, and NT1 was most efficient in fertilizer-into-product conversion. Under maize cultivation, the soil acted as N2O source, regardless of the management.


Assuntos
Agricultura/métodos , Poluição do Ar/prevenção & controle , Fertilizantes , Gases de Efeito Estufa/análise , Dióxido de Nitrogênio/análise , Zea mays/crescimento & desenvolvimento , Poluição do Ar/estatística & dados numéricos , Brasil , Solo
18.
Sci Total Environ ; 697: 133840, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31487598

RESUMO

The effects of different moisture contents on greenhouse gas (GHG) emissions from pig manure (PM) digested by black soldier fly larvae (BSFL) as well as the accompanying changes of nitrogen and carbon contents in gaseous emissions and residues were studied. A mixture of PM and corncob at the ratio of 2.2:1 was prepared with a moisture content of 45%. Then, distilled water was added to adjust the moisture contents of the mixture to 55%, 65%, 75% and 85%, respectively. The prepared mixtures were digested by BSFL for eight days. The results indicated that BSFL could reduce CH4, N2O and NH3 emissions respectively by 72.63-99.99%, 99.68%-99.91% and 82.30-89.92%, compared with conventional composting, while CO2 emissions increased potentially due to BSFL metabolism. With increasing moisture content, the cumulative CH4 emissions increased, while cumulative NH3 emissions peaked at 55% moisture content and then decreased. Interestingly, the tendency of total cumulative CO2 emissions was consistent with that of the total weight of BSFL. The total GHG emissions were about only 1% those from of traditional composting at the optimum moisture content (75%), which was the most favorable for the growth of BSFL. The nitrogen and carbon contents of BSFL content in all treatments accounted for 1.03%-12.67% and 0.25%-4.68% of the initial contents in the raw materials, respectively. Moreover, the residues retained 71.12%-90.58% carbon and 67.91%-80.39% nitrogen of the initial raw materials. Overall, our results suggest that BSFL treatment is an environment-friendly alternative for decreasing CH4, N2O and NH3 emissions as well as reducing global warming potential (GWP).


Assuntos
Compostagem , Gases de Efeito Estufa/análise , Esterco , Metano/análise , Simuliidae/fisiologia , Animais , Fertilizantes , Nitrogênio/análise
19.
Environ Sci Pollut Res Int ; 26(31): 31900-31912, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31489548

RESUMO

This study is among the first attempts to examine the effect of economic complexity as an indicator of sophisticated and knowledge-based production structures on CO2 emissions for 55 countries over the period of 1971-2014. The countries considered fall into three different income groups, namely high income, higher middle income, and lower middle income. The study employs the panel quantile regression methodology and tests the existence of the environmental Kuznets curve (EKC) hypothesis by including economic complexity and other control variables such as energy consumption, urbanization, and trade openness in its model. The results show that economic complexity has significant impacts on the environment. Based on the analysis, economic complexity has increased the environmental degradation in lower and higher middle-income countries, and has controlled CO2 emissions in high-income countries. Since economic complexity plays a significant role in environmental damage, it is crucial for low- and middle-income countries to adjust their current industrial and production policies to promote economic growth and at the same time protect the environment.


Assuntos
Dióxido de Carbono/análise , Desenvolvimento Econômico , Modelos Econométricos , Meio Ambiente , Gases de Efeito Estufa/análise , Renda , Políticas , Urbanização
20.
Environ Sci Pollut Res Int ; 26(28): 29246-29256, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31392620

RESUMO

To comprehend city-level driving mechanisms of carbon emissions, this paper utilizes spectral cluster and two-layer LMDI (logarithmic mean divisia index) method to systematically assess the contribution values of correlative factors from each cluster to Henan's carbon emissions increments, and accordingly comes up with more strategies about how to reduce carbon emissions for each cluster on the basis of driving forces of carbon emissions. The results of clustering and the decomposition are as follows: (1) the 18 prefecture-level cities in Henan were divided into five categories by spectral clustering, and there are similar development patterns within each category, so they can learn from each other to improve their own defects of development; (2) this paper utilizes the two-layer LMDI method to divide the factors affecting each cluster of carbon emissions into four types, which includes energy structure, energy intensity, per capita GDP, and population, and calculates the contribution value of each factor. It was concluded that the contribution value of per capita GDP dominantly drove up carbon emissions, while energy intensity played a significant role in offsetting them. Therefore, it is important for Henan's low-carbon development to control the expansion of economic activity and improve energy efficiency in the future.


Assuntos
Poluição do Ar/prevenção & controle , Carbono/análise , Gases de Efeito Estufa/análise , China , Cidades , Análise por Conglomerados , Fontes Geradoras de Energia , Produto Interno Bruto/estatística & dados numéricos , Modelos Teóricos
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