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1.
Rev Port Cir Cardiotorac Vasc ; 26(3): 205-208, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31734972

RESUMO

OBJECTIVE: To observe the impact of the use of capnography system adapted to cardiopulmonary bypass (CPB). To measure the concordance between values obtained from continuous monitoring of partial pressure of carbon dioxide in membrane oxygenator exhaustion (PeCO2) and the results observed on arterial blood gas test. METHODS: Participated in this study 40 patients submitted to elective cardiovascular surgery with CPB. They were divided into two groups: Group 1, with 20 patients submitted to the surgical procedure using blood gas analysis at intermittent intervals (20 - 30 minutes); Group 2, with 20 patients operated with a capnography system adapted applied to membrane oxygenator exhaustion and blood gas test. A test was used to compare arterial partial pressure of carbon dioxide (PaCO2) from group 1 and group 2. In group 2, the strength of the correlation between PeCO2 and PaCO2 was evaluated by a linear regression test. The Bland-Altman method was used to determine the degree of agreement between the two variables. RESULTS: Average and standard deviation of Group 1's PaCO2 (34.6 ± 7.44) and Group 2's PaCO2 / PeCO2 (36.5 ± 4.42) / (39.9 ± 3.98). There was no statistically significant difference in PaCO2 between the groups (P = 0.21). In group 2, PeCO2 and PaCO2 analyzed corrected for esophageal temperature obtained a positive linear correlation (r = 0.79, P < 0.001), the degree of agreement presented an average 3.47 ± 2.70 mmHg. CONCLUSION: The continuous PeCO2 monitoring from cardiopulmonary bypass circuit has a positive impact on the result of PaCO2. This instrument confirms and maintains the carbon dioxide (CO2) values into reference parameters.


Assuntos
Capnografia/métodos , Dióxido de Carbono/análise , Ponte Cardiopulmonar/instrumentação , Procedimentos Cirúrgicos Cardiovasculares/métodos , Gasometria , Humanos , Monitorização Intraoperatória , Oxigenadores de Membrana , Pressão Parcial
3.
Nature ; 574(7777): 237-241, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31578526

RESUMO

Earth is heading towards a climate that last existed more than three million years ago (Ma) during the 'mid-Pliocene warm period'1, when atmospheric carbon dioxide concentrations were about 400 parts per million, global sea level oscillated in response to orbital forcing2,3 and peak global-mean sea level (GMSL) may have reached about 20 metres above the present-day value4,5. For sea-level rise of this magnitude, extensive retreat or collapse of the Greenland, West Antarctic and marine-based sectors of the East Antarctic ice sheets is required. Yet the relative amplitude of sea-level variations within glacial-interglacial cycles remains poorly constrained. To address this, we calibrate a theoretical relationship between modern sediment transport by waves and water depth, and then apply the technique to grain size in a continuous 800-metre-thick Pliocene sequence of shallow-marine sediments from Whanganui Basin, New Zealand. Water-depth variations obtained in this way, after corrections for tectonic subsidence, yield cyclic relative sea-level (RSL) variations. Here we show that sea level varied on average by 13 ± 5 metres over glacial-interglacial cycles during the middle-to-late Pliocene (about 3.3-2.5 Ma). The resulting record is independent of the global ice volume proxy3 (as derived from the deep-ocean oxygen isotope record) and sea-level cycles are in phase with 20-thousand-year (kyr) periodic changes in insolation over Antarctica, paced by eccentricity-modulated orbital precession6 between 3.3 and 2.7 Ma. Thereafter, sea-level fluctuations are paced by the 41-kyr period of cycles in Earth's axial tilt as ice sheets stabilize on Antarctica and intensify in the Northern Hemisphere3,6. Strictly, we provide the amplitude of RSL change, rather than absolute GMSL change. However, simulations of RSL change based on glacio-isostatic adjustment show that our record approximates eustatic sea level, defined here as GMSL unregistered to the centre of the Earth. Nonetheless, under conservative assumptions, our estimates limit maximum Pliocene sea-level rise to less than 25 metres and provide new constraints on polar ice-volume variability under the climate conditions predicted for this century.


Assuntos
Água do Mar/análise , Dióxido de Carbono/análise , Foraminíferos/química , Sedimentos Geológicos/química , História Antiga , Camada de Gelo/química , Nova Zelândia , Oceanos e Mares , Isótopos de Oxigênio/análise , Pressão Parcial
5.
Microb Cell Fact ; 18(1): 161, 2019 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-31547820

RESUMO

BACKGROUND: Numerous studies have shown that stress induction and genetic engineering can effectively increase lipid accumulation, but lead to a decrease of growth in the majority of microalgae. We previously found that elevated CO2 concentration increased lipid productivity as well as growth in Phaeodactylum tricornutum, along with an enhancement of the oxidative pentose phosphate pathway (OPPP) activity. The purpose of this work directed toward the verification of the critical role of glucose-6-phosphate dehydrogenase (G6PDH), the rate-limiting enzyme in the OPPP, in lipid accumulation in P. tricornutum and its simultaneous rapid growth rate under high-CO2 (0.15%) cultivation. RESULTS: In this study, G6PDH was identified as a target for algal strain improvement, wherein G6PDH gene was successfully overexpressed and antisense knockdown in P. tricornutum, and systematic comparisons of the photosynthesis performance, algal growth, lipid content, fatty acid profiles, NADPH production, G6PDH activity and transcriptional abundance were performed. The results showed that, due to the enhanced G6PDH activity, transcriptional abundance and NAPDH production, overexpression of G6PDH accompanied by high-CO2 cultivation resulted in a much higher of both lipid content and growth in P. tricornutum, while knockdown of G6PDH greatly decreased algal growth as well as lipid accumulation. In addition, the total proportions of saturated and unsaturated fatty acid, especially the polyunsaturated fatty acid eicosapentaenoic acid (EPA; C20:5, n-3), were highly increased in high-CO2 cultivated G6PDH overexpressed strains. CONCLUSIONS: The successful of overexpression and antisense knockdown of G6PDH well demonstrated the positive influence of G6PDH on algal growth and lipid accumulation in P. tricornutum. The improvement of algal growth, lipid content as well as polyunsaturated fatty acids in high-CO2 cultivated G6PDH overexpressed P. tricornutum suggested this G6PDH overexpression-high CO2 cultivation pattern provides an efficient and economical route for algal strain improvement to develop algal-based biodiesel production.


Assuntos
Dióxido de Carbono/metabolismo , Diatomáceas/crescimento & desenvolvimento , Diatomáceas/genética , Ácidos Graxos/metabolismo , Glucosefosfato Desidrogenase/genética , Dióxido de Carbono/análise , Diatomáceas/metabolismo , Engenharia Genética , Glucosefosfato Desidrogenase/metabolismo , Microalgas/genética , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , NADP/metabolismo , Via de Pentose Fosfato , Fotossíntese
6.
Environ Monit Assess ; 191(10): 631, 2019 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-31520222

RESUMO

Gross primary productivity (GPP) is a vital ecosystem variable that is used as a proxy to study the functional behaviour of a terrestrial ecosystem and its ability to regulate atmospheric CO2 by working as a carbon pool. India, having the potential terrestrial ecosystem dynamics to absorb the atmospheric carbon dioxide to some extent, is one of the least-explored regions in terms of carbon monitoring studies. The current study evaluates the applicability of a newly developed, quantum yield-based, remote sensing data-driven diagnostic model called the Southampton Carbon Flux (SCARF). This model was used to estimate the annual and seasonal variability of the terrestrial GPP over the Indian region with a spatial resolution of 1 km during 2008. This modified version of the conventional production efficiency model successfully predicted GPP using meteorological variables (PAR, air temperature and dew point temperature), the fraction of photosynthetically active radiation and quantum yield of C3 and C4 plants as the key input parameters. The annual GPP values were in the range from 0 to 4147.55 g C m-2 year-1, with a mean value of 1507.32 g C m-2 year-1. The maximum and minimum GPP were during the summer monsoon and pre-monsoon, respectively. The seasonal and annual distributions of GPP over the study area obtained using the SCARF model, and the MODIS GPP product (MOD17A2H) were similar. However, MODIS was found to underestimate the GPP in all regions and an overestimation in eastern Himalaya region. The study reveals that environmental scalars, specifically water stress, are the pivotal controlling variables responsible for the variation of GPP in India. The estimates of the GPP in different regions of the study area were made using SCARF, and an eddy covariance technique was similar. The SCARF model can be used to estimate GPP on a global scale. SCARF appears to be a better model in terms of the simplicity of the algorithm, performance and resolution. Thus, it may give higher accuracy in carbon monitoring studies.


Assuntos
Atmosfera/química , Ciclo do Carbono/fisiologia , Dióxido de Carbono/análise , Produção Agrícola/estatística & dados numéricos , Monitoramento Ambiental/métodos , Fotossíntese/fisiologia , Carbono/análise , Ecossistema , Índia , Plantas , Tecnologia de Sensoriamento Remoto , Estações do Ano , Temperatura Ambiente
7.
Environ Pollut ; 254(Pt A): 112982, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31554143

RESUMO

Muzzle emissions from firing an M4 carbine rifle in a semi-enclosed chamber were characterized for an array of compounds to provide quantitative data for future studies on potential inhalation exposure and rangeland contamination. Air emissions were characterized for particulate matter (PM) size distribution, composition, and morphology; carbon monoxide (CO); carbon dioxide (CO2); energetics; metals; polycyclic aromatic hydrocarbons; and methane. Three types of ammunition were used: a "Legacy" (Vietnam-era) round, the common M855 round (no longer fielded), and its variant, an M855 round with added potassium (K)-based salts to reduce muzzle flash. Average CO concentrations up to 1500 ppm significantly exceeded CO2 concentrations. Emitted particles were in the respirable size range with mass median diameters between 0.33 and 0.58 µm. PM emissions were highest from the M855 salt-added ammunition, likely due to incomplete secondary combustion in the muzzle blast caused by scavenging of combustion radicals by the K salt. Copper (Cu) had the highest emitted metal concentration for all three round formulations, likely originating from the Cu jacket on the bullet. Based on a mass balance analysis of each round's formulation, lead (Pb) was completely emitted for all three round types. This work demonstrated methods for characterizing emissions from gun firing which can distinguish between round-specific effects and can be used to initiate studies of inhalation risk and environmental deposition.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Armas de Fogo/estatística & dados numéricos , Exposição por Inalação/análise , Material Particulado/análise , Dióxido de Carbono/análise , Monóxido de Carbono/análise , Chumbo/análise , Metano/análise , Niacinamida/análogos & derivados , Niacinamida/análise , Tamanho da Partícula , Hidrocarbonetos Policíclicos Aromáticos/análise , Vietnã
8.
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
9.
Nature ; 574(7777): 233-236, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31471591

RESUMO

Reconstructing the evolution of sea level during past warmer epochs such as the Pliocene provides insight into the response of sea level and ice sheets to prolonged warming1. Although estimates of the global mean sea level (GMSL) during this time do exist, they vary by several tens of metres2-4, hindering the assessment of past and future ice-sheet stability. Here we show that during the mid-Piacenzian Warm Period, which was on average two to three degrees Celsius warmer than the pre-industrial period5, the GMSL was about 16.2 metres higher than today owing to global ice-volume changes, and around 17.4 metres when thermal expansion of the oceans is included. During the even warmer Pliocene Climatic Optimum (about four degrees Celsius warmer than pre-industrial levels)6, our results show that the GMSL was 23.5 metres above the present level, with an additional 1.6 metres from thermal expansion. We provide six GMSL data points, ranging from 4.39 to 3.27 million years ago, that are based on phreatic overgrowths on speleothems from the western Mediterranean (Mallorca, Spain). This record is unique owing to its clear relationship to sea level, its reliable U-Pb ages and its long timespan, which allows us to quantify uncertainties on potential uplift. Our data indicate that ice sheets are very sensitive to warming and provide important calibration targets for future ice-sheet models7.


Assuntos
Mudança Climática/história , Água do Mar/análise , Calibragem , Dióxido de Carbono/análise , Foraminíferos/química , História Antiga , Camada de Gelo/química , Ilhas , Mar Mediterrâneo , Isótopos de Oxigênio/análise , Espanha , Incerteza
10.
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
11.
Microbiol Res ; 228: 126327, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31499402

RESUMO

The aim of this work was to investigate the early detection of anthracnose and soft rot diseases in cold stored strawberry fruit by evaluating the CO2 and volatile organic compounds (VOCs) released by the fungi Colletotrichum fragariae and Rhizopus stolonifer. Strawberries were stored at 5, 10 and 21 °C (control group) and the VOCs and CO2 production of inoculated and non-inoculated strawberries were followed by gas chromatography. To evaluate and estimate the growth of both fungi, the CO2 data were fitted to the Gompertz model. Data of the VOCs released at the end of the fungal growth were analyzed using principal components analysis (PCA) to discriminate between infected and non-infected strawberries. The results showed that fungal growth was affected by temperature and C. fragariae had a maximum growth after 14.6 h at 5 °C and R. stolonifer at 21 °C after 45.2 h. On the other hand, through VOCs released by C. fragariae and R. stolonifer and PCA, four groups were obtained: a) strawberry infected with C. fragariae, stored at 10 °C, b) strawberry infected with R. stolonifer, stored at 21 °C, c) control group kept at 10 °C and, d) strawberry infected with C. fragariae and control group (5 and 21 °C), and strawberry infected with R. stolonifer at 5 and 10 °C. In conclusion, CO2 and VOCs released by C. fragariae and R. stolonifer on strawberries could infer the presence of anthracnose and soft rot during storage of the fruit at low temperature.


Assuntos
Dióxido de Carbono/metabolismo , Temperatura Baixa , Colletotrichum/metabolismo , Fragaria/microbiologia , Frutas/microbiologia , Rhizopus/metabolismo , Compostos Orgânicos Voláteis/metabolismo , Dióxido de Carbono/análise , Armazenamento de Alimentos , Análise Multivariada , Doenças das Plantas/microbiologia , Rhizopus/crescimento & desenvolvimento , Compostos Orgânicos Voláteis/antagonistas & inibidores
12.
Sci Total Environ ; 691: 1144-1154, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31466196

RESUMO

Rising atmospheric carbon dioxide (CO2) may stimulate the proliferation of cyanobacteria. To investigate the possible physiological responses of cyanobacteria to elevated CO2 at different nutrient levels, Microcystis aeruginosa were exposed to different concentrations of CO2 (400, 1100, and 2200 ppm) under two nutrient regimes (i.e., in nutrient-rich and nutrient-poor media). The results indicated that M. aeruginosa differed in its responses to elevated atmospheric CO2 at different nutrient levels. The light utilization efficiency and photoprotection of photosystem II were improved by elevated CO2, particularly when cells were supplied with abundant nutrients. In nutrient-poor media, both total organic carbon and the polysaccharide/protein ratio of the extracellular polymeric substance increased with elevated CO2, accompanied by high cellular carbon/nitrogen ratios. Besides, cells growing with fewer nutrients were more prone to suffer intracellular acidification with elevated CO2 than those growing with abundant nutrients. Nonetheless, alkaline phosphate activity of cyanobacteria was improved by high CO2, provided that reduced pH was in the optimum range for alkaline phosphate activity. Nitrate reductase activity was inhibited by elevated CO2 regardless of nutrient levels, leading to a reduced nitrate uptake. These changes indicate that the biogeochemical cycling of nutrients would be affected by higher atmospheric CO2 conditions. Overall, cyanobacteria in eutrophic waters may benefit more than in oligotrophic waters from rising atmospheric CO2 concentrations, and evaluations of the influence of rising atmospheric CO2 on algae should account for the nutrient level of the ecosystem.


Assuntos
Atmosfera/química , Dióxido de Carbono/análise , Cianobactérias/fisiologia , Eutrofização
13.
Environ Monit Assess ; 191(9): 550, 2019 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-31396767

RESUMO

A field experiment was conducted at Indian Council of Agricultural Research-National Rice Research Institute, Cuttack, Odisha, India in the dry seasons of 2015 and 2016 to assess the water vapor flux (FH2O) and its relationship with other climatic variables. The FH2O and climatic variables were measured by an eddy covariance system and a micrometeorological observatory. Daily mean FH2O during the dry seasons of 2015 and 2016 were 0.009-0.092 g m-2 s-1 and 0.014-0.101 g m-2 s-1, respectively. Seasonal average FH2O was 14.6% higher in 2016 than that in 2015. Diurnal variation for FH2O showed a bell-shaped curve with its peak at 13:30-14:00 Indian Standard Time (IST) in both the years. Carbon dioxide flux was found higher with rise in FH2O. This relationship was stronger at higher vapor pressure deficit (VPD) (20 ≤ VPD ≤ 40 and VPD > 40 hPa). The FH2O showed significant positive correlation with latent heat flux, net radiation flux, photosynthatically active radiation, air, water and soil temperatures, shortwave down and upwell radiations, maximum and minimum temperatures, evaporation, and relative humidity in both the years. Principal component analysis showed that FH2O was very close to latent heat flux in both the years (Pearson correlation coefficient close to 1). The two-dimensional observation map of the principal component F1 and F2 showed the observations taken during the vegetative stage and panicle initiation stage, and flowering stage and maturity stage were closer to each other. It can be concluded that the most important climatic variables controlling the FH2O were latent heat of vaporization, net radiation, air temperature, soil temperatures, and water temperature.


Assuntos
Ciclo do Carbono/fisiologia , Monitoramento Ambiental/métodos , Oryza/química , Vapor/análise , Agricultura , Dióxido de Carbono/análise , Ecossistema , Índia , Análise de Componente Principal , Estações do Ano , Solo/química , Temperatura Ambiente , Água/química
14.
Environ Monit Assess ; 191(9): 563, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31410642

RESUMO

This study aims to determine a baseline for natural soil carbon dioxide (CO2) flux at the surface based on long-term field measurements, with the ultimate purpose to detect the gas leakage at CO2 geological storage sites. CO2 surface monitoring is a tool that measures the safety and effectiveness of CO2 capture and storage (CCS), a technology which is believed to be a reliable approach to mitigate the CO2 emission. However, the fluctuations of naturally occurring CO2 in soil layers complicate the leakage detection as the soil connects both the underground layers and the atmosphere. In this regard, this study not only investigates the natural surface CO2 flux behavior but also develops an equation to estimate the surface CO2 flux with respect to the soil moisture content and temperature. To meet this end, two values within the CO2 flux equation were defined and calculated based on the field measurements; a, representing a water saturation-dependent value, and b, representing the temperature sensitivity (independent of the water saturation). The results show a good agreement between estimated and measured data. Upon which, the maximum baseline for surface CO2 flux was derived and used as a threshold to detect the potential CO2 leakage in the candidate field (INAS, Japan).


Assuntos
Dióxido de Carbono/análise , Monitoramento Ambiental/métodos , Solo/química , Atmosfera/química , Geologia , Japão , Temperatura Ambiente , Água/química
15.
Mar Pollut Bull ; 146: 767-778, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31426219

RESUMO

Various biogeochemical processes complicate carbon dioxide (CO2) behaviour in coastal oceans. Through eight summer surveys, detailed variations in CO2 mechanisms in the urbanized Jiaozhou Bay, China, were analysed. During the rainless period, respiration and dissolved inorganic carbon input from treated wastewater made the northeastern region a strong CO2 source, while the western region with cleaner seawater was a weak source because calcium carbonate (CaCO3) precipitation exceeded primary production. Rainfall events with different intensities and locations caused significantly different effects. When rainfall occurred over the sea, enhanced primary production caused a CO2 sink; when rainfall induced little terrestrial pollutant input, CaCO3 precipitation exceeded net primary production, leading to a CO2 source. When heavy rain caused bulk runoff, the northeastern region was a strong CO2 source because rivers flowing through downtown regions inputted considerable organic matter, while in the western region, runoff through suburbs and wetlands led to a strong sink.


Assuntos
Dióxido de Carbono/análise , Água do Mar/análise , Baías , Carbonato de Cálcio , Carbono/análise , Sequestro de Carbono , China , Clorofila , Monitoramento Ambiental , Concentração de Íons de Hidrogênio , Oceanos e Mares , Chuva , Rios , Salinidade , Estações do Ano , Temperatura Ambiente , Urbanização , Águas Residuárias/análise , Áreas Alagadas
16.
Sci Total Environ ; 686: 1164-1172, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31412512

RESUMO

Storm surges can substantially alter the water level and salinity in tidal salt marshes. Little is known about how changes experienced during storm surges affect greenhouse gas emissions (GHG; CO2, CH4, N2O) from tidal salt marsh soils. Understanding how storm surges influence ecosystem processes is critical for evaluating the ecosystem's sensitivity to sea level rise. To explore how hurricane-induced changes in salinity affect GHG emissions, we exposed intact soil mesocosms (0-9 cm depth) from a Mid-Atlantic temperate salt marsh to pulse changes in salinity experienced at the site before, during, and after Hurricane Joaquin in 2015. Soil temperature, oxygen, and water level were kept constant to avoid confounding effects throughout the experiment. Automated measurements (hourly resolution) of soil GHG emissions were recorded in control (i.e., no salinity changes) and treatment mesocosms, and combined with soil pore water chemistry (i.e., SO42-, S2-, Fe2+, TNb, redox potential, pH) to characterize the biogeochemical responses. Using mixed effects models, we found that the role of different biogeochemical processes, such as sulfur cycling, changed throughout the experiment, underscoring the complex nature of GHG emissions in tidal salt marsh soils. Overall, soils subjected to a salinity decrease had greater GHG emissions than control soils, which were maintained at 17 ppt. The treatment soils had a 24% and 23% increase in global warming potential (20- and 100-year scenarios, respectively) indicating that storm surges can produce pulses of GHG emissions. However, both CH4 and N2O emissions returned to baseline values (following hysteresis responses) when initial conditions were reestablished. The results support the fact that tidal salt marshes are resilient ecosystems, as soil GHG emissions recovered relatively quickly from the pulse event.


Assuntos
Dióxido de Carbono/análise , Gases de Efeito Estufa/análise , Metano/análise , Óxido Nitroso/análise , Salinidade , Solo/química , Delaware , Movimentos da Água , Tempo (Meteorologia) , Áreas Alagadas
17.
Nat Commun ; 10(1): 3344, 2019 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-31409792

RESUMO

Tropical ecosystems are large carbon stores that are vulnerable to climate change. The sparseness of ground-based measurements has precluded verification of these ecosystems being a net annual source (+ve) or sink (-ve) of atmospheric carbon. We show that two independent satellite data sets of atmospheric carbon dioxide (CO2), interpreted using independent models, are consistent with the land tropics being a net annual carbon emission of [Formula: see text] [Formula: see text] and [Formula: see text] petagrams (PgC) in 2015 and 2016, respectively. These pan-tropical estimates reflect unexpectedly large net emissions from tropical Africa of [Formula: see text] PgC in 2015 and [Formula: see text] PgC in 2016. The largest carbon uptake is over the Congo basin, and the two loci of carbon emissions are over western Ethiopia and western tropical Africa, where there are large soil organic carbon stores and where there has been substantial land use change. These signals are present in the space-borne CO2 record from 2009 onwards.


Assuntos
Atmosfera/química , Ciclo do Carbono , Dióxido de Carbono/análise , Mudança Climática , África , Conjuntos de Dados como Assunto , Florestas , Solo/química , Clima Tropical
18.
Environ Monit Assess ; 191(9): 587, 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31440847

RESUMO

The international community is more than ever before worrying about the unremitting global warming and climate change and the responsibility of extensive energy use for that situation. This article contributes to the existing literature by examining whether energy consumption predicts CO2 emissions during the past 50 years in the five most polluting nations in the world. To do this, we have been using the recently developed predictability test of Westerlund and Narayan (Journal of Banking and Finance, 36, 2632-2640, 2012, Journal of Financial Econometrics, 13, 342-375, 2015). We take thereby into account the problem of endogeneity and persistence in the explanatory variable. Likewise, this test has the advantage of treating the problem of heteroscedasticity. Using several predictive evaluation measures and assuming the historical average as a benchmark, we find that the basic model of the predictability test of Westerlund and Narayan (2012, 2015) surpasses the benchmark model. These findings reveal that primary energy consumption predicts CO2 emissions in the world and all countries, for different forecast horizons. Further, the in-sample evidence of predictability has been supported by the out-of-sample analysis.


Assuntos
Dióxido de Carbono/análise , Mudança Climática/estatística & dados numéricos , Fontes Geradoras de Energia/estatística & dados numéricos , Monitoramento Ambiental/métodos , Poluição Ambiental/análise
19.
Ying Yong Sheng Tai Xue Bao ; 30(7): 2447-2456, 2019 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-31418248

RESUMO

The static chamber-gas chromatography method was applied to observe CO2 fluxes across the water-air interface from different aquaculture systems, including four groups of mesocosms, i.e., blank control system (CK), monoculture system of Sebastes schlegelii (F), monoculture system of Chlamys farreri (B) and polyculture system of S. schlegelii and C. farreri (FB). Meanwhile, the physical, chemical and biological indices of the water were measured. The results showed that the group CK was a stable CO2 source, with the mean flux of 12.42 mg·m-2·h-1. The group B was a CO2 source during the early and middle periods of the experiment and a CO2 sink at the end of the experiment, with the mean flux during the experiment being 10.95 mg·m-2·h-1. The change trends of CO2 flux in the group F and FB were generally consistent, acting as CO2 sources in the early period and as CO2 sinks subsequently. The mean fluxes of those two groups during the expe-riment were -3.53 and -10.49 mg·m-2·h-1, respectively. Water pH was a good predictor for CO2 flux across the water-air interface according to the result of regression analysis, with pH value of 8.25 as the critical threshold between efflux and influx. The net primary production of water column was the main factor influencing the CO2 flux, indicating that phytoplankton might be the main internal force regulating the CO2 flux across the water-air interface. Our results indicated that C. farreri at present stocking density in the polyculture system could promote phytoplankton biomass as well as primary production and therefore enhance the CO2 sink function.


Assuntos
Poluentes Atmosféricos/análise , Aquicultura , Dióxido de Carbono/análise , Pectinidae , Animais , Metano , Água
20.
Ying Yong Sheng Tai Xue Bao ; 30(8): 2717-2724, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31418197

RESUMO

Rice straw is a potential material for bioenergy production. Elevated atmospheric carbon dioxide (CO2) concentration changed the quantity and quality of rice straw, thus changing its bioenergy production potential. In this experiment, we collected rice straw from China Free Air CO2 Enrichment Platform (FACE). Three rice varieties, Wuyunjing 27, Y Liangyou 900 and Nipponbare N16, were selected from the FACE platform (the CO2 concentration in the experimental group was controlled at 570 µmol ·mol-1, which was 200 µmol ·mol-1 higher than the control group), the chemical composition of which was analyzed. The results showed that elevated CO2 concentration significantly increased C content, C/N, and the content of non-structural carbohydrates in straw. Elevated CO2 concentration significantly increased total sugar release by 8.8%, 6.7% and 9.9% in Wuyunjing 27, Y liangyou 900 and N16, respectively. Elevated CO2 concentration significantly enhanced the biomass of N16 straw, but had no effect on the straw biomass of the other two rice varieties. The total sugar yield of N16 increased most significantly with elevated CO2 concentration, reaching 19.2%. Our results indicated that elevated CO2 concentration could improve the quality and quantity of rice straw, thereby increasing the utilization potential of biofuel.


Assuntos
Dióxido de Carbono/análise , Oryza/química , Atmosfera/química , Biomassa , China
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