Trend analysis using nonhomogeneous stochastic diffusion processes. Emission of CO<Subscript>2</Subscript>; Kyoto protocol in Spain

In this study, we propose a methodology to analyse the gradual secular trends present in the time evolution of certain endogenous variables, which are of particular interest in environmental research. This methodology is based on modelling such variables by nonhomogeneous stochastic diffusion processes, the trend functions of which may be made to depend on other, exogenous, variables, which are controllable and which affect and model, in turn, the possible irregularities of such trends. The methodology is applied to analyse the evolution of the emission of CO₂ in Spain, and it is shown that the evolution of the Spanish GDP affects the trend component. These circumstances are considered in the context of Spain’s non-compliance with the Kyoto protocol on controlling the emission of greenhouse gases.     

Detection, modelling and estimation of non-linear trends by using a non-homogeneous Vasicek stochastic diffusion. Application to CO2 emissions in Morocco

This paper proposes a new stochastic model, based on a Vasicek non-homogeneous diffusion process, in which the non-linear trend coefficient (drift) depends on deterministic functions that describe the dynamic evolution of certain exogenous variables. After studying its probabilistic characteristics, and in particular the transition probability density and trend function, the associated stochastic inference based on discrete sampling in time is established using maximum likelihood methodology. This model is applied to detect, estimate and model the non-linear trend present in data corresponding to CO₂ emissions in Morocco. Energy and financial variables that affect the behaviour of this trend are also detected, and substantial improvement provided by this non-homogeneous model with respect to its corresponding homogeneous version, is confirmed.     

Analysis of Stock Market Development and CO2 Emissions on OECD Countries via an Empirical Model

Accompanying economic growth, CO₂ emissions have polluted the natural environment worldwide. This study highlights the special problems with stock market development and CO₂ emissions in 25 Organization for Economic Cooperation and Development (OECD) countries during 1971–2007 to trace the trend of CO₂ emissions while countries grow their economies. A panel‐data model is applied to analyze the relationships between stock market (SM) development, energy consumption, gross domestic product (GDP), and CO₂ emissions in 25 OECD countries. Low‐GDP countries show different results from high‐GDP countries in the trends of SM development and CO₂ emissions, and dynamic effects occur in SM development and CO₂ emissions under various GDP conditions. There is a negative relationship between SM development and CO₂ emissions if countries enjoy high economic growth, which means that these countries avoid CO₂ emissions through SM development. However, a positive relationship is found between SM development and CO₂ emissions if countries experience low economic growth, which means that SM development does not show the boycott‐effect relationship with CO₂ emissions when countries experience low levels of economic development. This study shows a correlation between SM development and CO₂ emissions among OECD countries.     

典型农业流域不同类型池塘水体CO2排放特征

内陆水体是大气CO₂收支估算的重要组成部分。农业流域分布着大量池塘景观水体,且具备蓄洪抗旱、消纳污染、水产养殖等多种功能。但是,农业流域不同功能的小型池塘CO₂排放特征尚不清楚。本研究以极具农业流域代表性的烔炀河流域为研究对象,选取流域中用于水产养殖(养殖塘)、生活污水承纳(村塘)、农业灌溉(农塘)、蓄水(水塘)的4个功能不同的景观池塘,基于为期1年的野外实地观测,以明确农业流域小型池塘CO₂排放特征。结果表明,不同功能池塘水体CO₂排放差异显著,受养殖活动、生活污水输入和农田灌溉等人类活动影响,养殖塘((80.37±100.39) mmol/(m²·d))、村塘((48.69±65.89) mmol/(m²·d))和农塘((13.50±15.81) mmol/(m²·d))是大气CO₂的热点排放源,其CO₂排放通量分别是自然蓄水塘((4.52±23.26) mmol/(m²·d))的18、11和3倍。统计分析也表明,该流域池塘CO₂排放变化总体上受溶解氧、营养盐等因素驱动。4个不同景观池塘CO₂排放通量全年均值为(37.31±67.47) mmol/(m²·d),是不容忽视的CO₂排放源,其中养殖塘和村塘具有较高的CO₂排放潜力,在未来研究中需要重点关注。     

Effects of soil compaction,rain exposure and their interaction on soil carbon dioxide emission

Soils release more carbon, primarily as carbon dioxide (CO₂), per annum than current global anthropogenic emissions. Soils emit CO₂ through mineralization and decomposition of organic matter and respiration of roots and soil organisms. Given this, the evaluation of the effects of abiotic factors on microbial activity is of major importance when considering the mitigation of greenhouse gases emissions. Previous studies demonstrate that soil CO₂ emission is significantly affected by temperature and soil water content. A limited number of studies have illustrated the importance of bulk density and soil surface characteristics as a result of exposure to rain on CO₂ emission, however, none examine their relative importance. Therefore, this study investigated the effects of soil compaction and exposure of the soil surface to rainfall and their interaction on CO₂ release. We conducted a factorial laboratory experiment with three soil types after sieving (clay, silt and sand soil), three different bulk densities (1·1 g cm^–3, 1·3 g cm^–3, 1·5 g cm^–3) and three different exposures to rainfall (no rain, 30 minutes and 90 minutes of rainfall). The results demonstrated CO₂ release varied significantly with bulk density, exposure to rain and time. The relationship between rain exposure and CO₂ is positive: CO₂ emission was 53% and 42% greater for the 90 minutes and 30 minutes rainfall exposure, respectively, compared to those not exposed to rain. Bulk density exhibited a negative relationship with CO₂ emission: soil compacted to a bulk density of 1·1 g cm^–3 emitted 32% more CO₂ than soil compacted to 1·5 g cm^–3. Furthermore we found that the magnitude of CO₂ effluxes depended on the interaction of these two abiotic factors. Given these results, understanding the influence of soil compaction and raindrop impact on CO₂ emission could lead to modified soil management practices which promote carbon sequestration. Copyright © 2012 John Wiley & Sons, Ltd.     

湖、库水体N2O排放研究进展

湖、库水体是重要的N₂O排放源,在全球氮素循环及全球气候变化中具有重要作用.本文综述了目前有关湖、库水体N₂O排放研究进展,重点介绍湖、库水体N₂O产生和排放的过程、不同时空尺度的排放特征、N₂O排放的影响因子框架及监测方法.湖、库水体N₂O不仅源于内部微生物硝化作用、反硝化作用、硝化-反硝化耦合作用、脱氮作用以及极少数底栖无脊椎动物代谢过程,同时流域上游河流汇入、地表径流输入、污水排放以及地下水排泄等构成湖、库水体N₂O的重要外源,但目前对内源/外源的相对贡献的定量化研究不足;湖、库水体N₂O排放方式包括扩散、植物传输及少量气泡排放,对水库而言,大坝下游水电涡轮机形成的脱气作用可能是N₂O排放的潜在途径.对文献综合分析表明,湖、库水体N₂O排放通常呈现明显的季节变化（夏季>冬季）和日变化,同时在全球（一般低纬度>高纬度）、区域及水体内部等不同尺度上表现出显著的空间变异性;这种时空变异特征主要受到湖、库自身理化因子（温度、营养盐、溶解氧、C/N、水文）、生物因子（水生植物、藻华）以及陆域人类活动（污水排放、农业活动以及城市化等）的影响;湖、库N₂O排放不同监测方法的差异也是潜在的影响因素,传统的漂浮箱法和薄边界层法均可能低估水体N₂O排放通量,未来需将传统的监测方法与新型的涡度相关法相结合,减小监测方法的不确定性.结合当前湖、库水体N₂O排放的研究不足,建议未来可以从湖、库N₂O产生的微生物机制,区域尺度上人类活动与湖、库群N₂O排放的耦合关系,水陆交错带的产、排过程,变化环境下的湖、库N₂O排放以及监测方法等方面深入研究.     

不同水文情景下洪泽湖二氧化碳排放通量特征及影响因素

内陆水域二氧化碳(CO₂)排放是全球碳平衡的重要组成部分,全球CO₂排放通量估算通常有很大不确定性,一方面源于CO₂排放数据观测的时空离散性,另一方面也是缺少水文情景与CO₂排放通量关联性的研究.本文观测了2018年洪泽湖不同水文情景表层水体CO₂排放通量特征,并探讨其影响因素.结果表明,洪泽湖CO₂排放通量为丰水期((106.9±73.4) mmol/(m²·d))>枯水期((18.7±13.6) mmol/(m²·d))>平水期((5.2±15.5) mmol/(m²·d)),且碳通量由丰(310.2~32.0 mmol/(m²·d))、枯(50.8~2.2 mmol/(m²·d))、平(-17.3~39.8 mmol/(m²·d))3种水文情景的交替表现出湖泊碳源到弱碳汇的转变,空间上CO₂排放通量总体呈现北部成子湖区低、南部过水湖区高的分布趋势.洪泽湖CO₂排放对水文情景响应敏感,特别是上游淮河流域来水量的改变,是主导该湖CO₂排放时空分异的重要因子.丰水期湖泊接纳了淮河更多有机和无机碳的输入,外源碳基质的降解和矿化显著促进了水体CO₂的生产与排放,同时氮、磷等营养物质的大量输入,加剧了水体营养化程度,进一步提高CO₂排放量,间接反映出人类活动对洪泽湖CO₂变化的深刻影响.平、枯水期随着上游淮河来水量的减少,驱动水体CO₂排放的因素逐渐由外源输入转变为水体有机质的呼吸降解.此外,上游河口区DOM中陆源类腐殖质的累积与矿化能够促进CO₂的排放,而内源有机质组分似乎并没有直接参与CO₂的排放过程.研究结果揭示了水文情景交替对湖库CO₂排放的重要影响,同时有必要进行高频观测以进一步明晰湖泊的碳通量变化及其控制因素.     

Summit CO2 emission rates by the CO2/SO2 ratio method at Kīlauea Volcano,Hawaiʻi,during a period of sustained inflation

The emission rate of carbon dioxide escaping from the summit of Kīlauea Volcano, Hawai?i, proved highly variable, averaging 4900 ± 2000 metric tons per day (t/d) in June–July 2003 during a period of summit inflation. These results were obtained by combining over 90 measurements of COSPEC-derived SO₂ emission rates with synchronous CO₂/SO₂ ratios of the volcanic gas plume along the summit COSPEC traverse. The results are lower than the CO₂ emission rate of 8500 ± 300 t/d measured by the same method in 1995–1999 during a period of long-term summit deflation [Gerlach, T.M., McGee, K.A., Elias, T., Sutton, A.J. and Doukas, M.P., 2002. Carbon dioxide emission rate of Kīlauea Volcano: Implications for primary magma and the summit reservoir. Journal of Geophysical Research-Solid Earth, 107(B9): art. no.-2189.]. Analysis of the data indicates that the emission rates of the present study likely reflect changes in the magma supply rate and residence time in the summit reservoir. It is also likely that emission rates during the inflation period were heavily influenced by SO₂ pulses emitted adjacent to the COSPEC traverse, which biased CO₂/SO₂ ratios towards low values that may be unrepresentative of the global summit gas plume. We conclude that the SO₂ pulses are consequences of summit re-inflation under way since 2003 and that CO₂ emission rates remain comparable to, but more variable than, those measured prior to re-inflation.     

Gas exchange between Baikal and the atmosphere during under-ice period

In the under-ice period, gas exchange between Baikal and the atmosphere is taking place through a system of coastal and perennial fractures and airholes in the ice, as well as through the surface of the ice-free part of the lake at the Angara source [24]. The total area of the open water never exceeds 0.03% of lake water area. The emission of CO₂ in the course of ice sublimation over the entire period is ≤0.02 g CO₂ from 1 m². The transport of dissolved gases from under-ice water into the atmosphere is limited by molecular diffusion in microfractions of ice cover. The narrow daily variations of CO₂ in the air in lake coastal zone is due to the effect of populated localities on its coast and large coniferous forests, which serve as diffuse sources of CO₂, as well as diurnal variations of the direction and velocity of air mass transport by local winds.     

On the accumulative contribution of CO2 emission from China to global climate change

A study of the contribution to global climate change from China’s CO₂ emission is conducted using the FIO-ESM v1.0 climate model. A series of sensitivity experiments are performed to identify two kinds of contributions to global climate change of China’s CO₂ emission due to fossil fuel combustion: one is the pure contribution which is the historical climate response from the sensitivity experiment forced only by China’s CO₂ emission, the other is the accumulative contribution which is proposed in this research and defined as the difference of historical climate responses between the experiments forced by all countries’ CO₂ emission and other countries’ CO₂ emission excluding China. The pure contribution approach considers the total CO₂ discharged by China, while the accumulative contribution approach considers not only the discharge amount of China but also the discharge order of China and other countries. The latter is a more realistic approach to quantify the contribution of CO₂ emission to the historical change of atmospheric CO₂ concentration, surface air temperature (SAT), sea surface temperature (SST) and sea ice coverage in the Arctic. Model results show that from the accumulative perspective, the ratio of the contribution of CO₂ emission from China for the increase of atmospheric CO₂ concentration, SAT and SST, and the decrease of the sea ice coverage in the Arctic to that from all other countries excluding China varies from 8% to 92%, 5% to 95%, 9% to 91% and 18% to 82%, respectively. Here we take the contribution of China’s CO₂ emission as an example, the contribution of CO₂ emission from any other country or area can be evaluated by the same approach.     

亚热带城市湖泊与河流CO2气体通量特征及其影响因素

湖泊、河流等内陆水体是连接陆地生态系统和海洋的“长程碳环路”的重要节点,也是温室气体二氧化碳(CO₂)排放源,在调节陆地、海洋间的碳迁移转换中发挥着重要作用。相对于自然水体,城市水体因面积小、水深浅且受监测方法限制,水-气界面碳通量经常被忽略。为探讨我国亚热带城市水体温室气体排放特征,本研究以湖南省长沙市典型城市水体,包括洋湖、西湖、松雅湖、月湖4个湖泊和湘江长沙段为研究对象,分别于2022年4和10月采用光化学反馈-腔增强吸收光谱法(OF-CEAS)和扩散模型法对水-气界面CO₂通量进行对比测定。结果表明,长沙城市湖泊与河流春季为CO₂排放源,秋季为吸收汇,河流水-气界面CO₂通量呈显著季节差异。河湖之间CO₂通量在春季表现为显著差异,秋季差异不显著。CO₂通量与水体溶解氧、水体总氮浓度等呈显著正相关。2种方法的CO₂通量对比测定在湖泊上显著相关,但对河流而言相关性不显著。研究揭示的城市湖泊与河流CO₂气体的排放特征有利于深入探究城市水体碳的迁移转化,可对全面了解全球气候变化过程和河湖湿地温室气体减排和调控提供科学支撑。     

藻型湖区氧化亚氮排放特征及其影响因素

湖泊等内陆水体是大气N₂O潜在的重要排放源,也是全球N₂O收支估算的重要组成部分。目前全球湖泊普遍面临富营养化和蓝藻暴发等问题,明晰藻型湖泊N₂O排放强度及其环境影响因子对准确估算湖泊N₂O排放和预测其未来变化至关重要。本研究选择太湖藻型湖区为研究对象,同时选取人为活动影响较小的湖心区作为对比区域,基于2011年8月至2013年8月为期2年的逐月连续观测,探讨藻型湖区N₂O排放特征及其影响因素。结果表明,藻型湖区呈现极强的N₂O排放,其排放通量为(4.88±3.05) mmol/(m²·d),是参考区域(湖心:(2.10±4.31) mmol/(m²·d))的2倍多。此外,在藻型湖区中不同点位N₂O排放差异显著,受河流外源输入影响,近岸区是N₂O的热点排放区,其年均排放通量高达10.93 mmol/(m²·d)。连续观测表明N₂     

Anomalous Diffuse CO2 Emissions at the Masaya Volcano (Nicaragua) Related to Seismic-Volcanic Unrest

Anomalous changes in the diffuse emission of carbon dioxide within the Masaya caldera have been observed before two seismic events that occurred at 10 and 30 km from the observation site. Their epicenters are located, respectively, south of Managua in Las Colinas (4.3 magnitude) and the Xiloa caldera (3.6 magnitude), in 2002 and 2003, recorded by the geochemical station located at El Comalito, Masaya volcano (Nicaragua). Anomalous increases were observed, which occurred around 50 and 8 days before the main seismic event that took place in Las Colinas, and 4 days before the seismic swarm at the Xiloa caldera, with a maximum CO₂ efflux of 9.3 and 10.7 kg m^?2 day^?1, respectively. The anomalous CO₂ efflux increases remained after filtering with multiple regression analysis was applied to the CO₂ efflux time series, which indicated that atmospheric variables, during the first 4 months, explained 23 % CO₂ variability, whereas, during the rest of the time series, CO₂ efflux values are poorly controlled with only 6 %. The observed anomalies of the diffuse CO₂ emission rate might be related to pressure changes within the volcanic–hydrothermal system and/or to geostructural changes in the crust due to stress/strain changes caused before and during the earthquakes’ formation, and seem not to be related to the activity of the main crater of Masaya volcano.     

三峡水库澎溪河水-气界面CO2、CH4扩散通量昼夜动态初探

三峡水库温室气体效应近年来备受关注.为揭示三峡水库典型支流澎溪河水-气界面CO₂和CH₄通量的昼夜动态规律,明晰短时间尺度下该水域温室气体释放的影响因素,在2010年6月至2011年5月的一个完整水文周年内,选择4个具有代表性的时段(2010年8、11月和2011年2、5月)对澎溪河高阳平湖水域开展昼夜跟踪观测.结果表明:2010年8、11月和2011年2、5月4次采样的CO₂日总通量值分别为-8.34、73.94、28.13和-20.12 mmol/(m²·d),相应的CH₄日总通量值分别为2.22、0.11、0.32和7.16 mmol/(m²·d),不同时期昼夜变化明显.研究水域CO₂和CH₄通量过程不具同步性:CO₂昼夜通量变化可能更显著地受到水柱光合/呼吸过程的影响,但瞬时气象过程(水汽温差、瞬时风速等)在高水位时期亦可对CO₂通量产生显著影响;CH₄昼夜通量变化与水温条件改变更为密切.     

CO2 and H2S concentrations in the atmosphere at the Solfatara of Pozzuoli

The CO₂ and H₂S concentration in the Solfatara atmosphere has been measured. The concentrations of both gases are higher neraby the more active areas and decrease away from them. A sharp horizontal and vertical gradient of the CO₂ content has been recognized.Such gradient is assumed to result from a diffusion of gas from the ground to the atmosphere.The total output of CO₂ has been computed based on a turbulent diffusion model. The obtained value is in good agreement with previously abserved values (Italiano et al., 1984).The feasibility of monitoring the atmosphere of Solfatara for either gas hazard and surveillance of volcanic activity has also been evaluated.     

过坝下泄水流中温室气体排放速率的数值模拟

当水流通过泄洪建筑物下泄时,水体中所溶解的温室气体(二氧化碳(CO2)、甲烷(CH4)等)会因为所受压力的瞬间改变而导致溶解度降低,从而造成气液之间传质的发生及水中温室气体的排放.然而,目前对于泄流条件下水中温室气体排放的研究还较为缺乏.鉴于原型观测与模型试验的局限性,本文建立了大坝泄流条件下温室气体排放速率的数学模型...     

Space-time precipitation reflecting climate change

Abstract

A methodology has been developed and applied to an eastern Nebraska, USA, case study to estimate the space-time distribution of daily precipitation under climate change. The approach is based on the analysis both of the type and of the Markov properties of atmospheric circulation patterns (CPs), and a stochastic linkage between daily (here 500 hPa) CP types and daily precipitation events. Historical data and General Circulation Model (GCM) output of daily CPs corresponding to 1 × CO₂ and 2 × CO₂ are considered. Time series of both local and regional precipitation corresponding to each of those cases were simulated and their statistical properties were compared. Under the dry continental climate of eastern Nebraska, a highly variable spatial response to climate change was obtained. Most of the local and the regional average precipitation values reflect, under 2 × CO₂, a somewhat wetter and a more variable precipitation regime in eastern Nebraska. The sensitivity of the results to the GCM utilized should be considered.     

Secular variations of carbon and helium isotopes at Izu-Oshima Volcano, Japan

Secular variations in ¹³C/¹²C ratios and chemical compositions of gas samples from October 1986 to July 1992 are reported from a 92–95 °C steam well located about 3 km north of Mt. Mihara, an active volcano on Izu-Oshima Island, Japan. The δ¹³C value steeply increased from −2.97‰ (relative to PDB carbonate) in December 1986 to −1.15‰ in March 1988 and then gradually decreased to −1.75‰ in July 1992. Over the same period, the CO₂ content changed similarly with time, even though the experimental error is relatively large. These variations are consistent with helium isotope changes. Initially rapid and then slow enhancements of ³He/⁴He ratio, δ¹³C value and CO₂ content are invoked by violent eruptions of Izu-Oshima volcano from 15 November to 18 December 1986. After the eruptive activity, depletion of magmatic gas emission and subsequent mixing with crustal fluids in the hydrothermal system may produce the gradual decreases of ³He/⁴He ratio, δ¹³C value and CO₂ content. Taking into account the rates of these decreases, we suggest that helium and carbon isotope ratios will return to the situation of before the magmatic eruption within 15 years.     

Seasonal variations and mechanism for environmental control of NEE of CO2 concerning the Potentilla fruticosa in alpine shrub meadow of Qinghai-Tibet Plateau

The study by the eddy covariance technique in the alpine shrub meadow of the Qinghai-Tibet Plateau in 2003 and 2004 showed that the net ecosystem carbon dioxide exchange (NEE) exhibited noticeable diurnal and annual variations, with more distinct daily changes during the warmer seasons. The CO₂ emission of the shrub ecosystem culminated in April and September while the CO₂ absorption capacity reached a maximum in July and August. The absorbed carbon dioxide during the two consecutive years was 231.4 and 274.8 g CO₂·m⁻² respectively, yielding an average of 253.1 gCO₂·m⁻² per year: that accounts for a large proportion of absorbed CO₂ in the region. Obviously, the diurnal carbon flux was negatively related to temperature, radiation and other atmospheric factors. Still, minute discrepancies in kurtosis and duration of carbon emission/absorption were detected between 2003 and 2004. It was found that the CO₂ flux in the daytime was similarly affected by photosynthetic photon flux density in both years. Temperature appears to be the most important determinant of CO₂ flux: specifically, the high temperature during the plant growing season inhibits the carbon absorption capacity. One potential explanation is that soil respiration is enhanced under such condition. Analysis of biomass revealed that the annual net carbon fixed capacity of aboveground and belowground biomass was 544.0 in 2003 and 559.4 g C·m⁻² in 2004, which coincided with the NEE absorption capacity (63.1 g C·m⁻² in 2003 and 74.9 g C·m⁻² in 2004) in the corresponding plant growing season.

     

fCO2 variability in the Bay of Biscay during ECO cruises

The Bay of Biscay is part of the North Atlantic Ocean, the most important sink of CO₂, and a subduction zone of mode waters that favours the entry of carbon to the ocean interior. To investigate the seasonal and interannual variability of CO₂ uptake, continuous underway measurements of the partial pressure of CO₂ at sea surface were performed along a commercial route between Vigo (Spain) and St. Nazaire (France). An unattended measuring system of CO₂ fugacity (fCO₂), with meteorological station, and temperature, salinity, oxygen and fluorescence sensors, was installed on board of ships of opportunity (RO-RO L’Audace and RO-RO Surprise).