Carbon dioxide dynamics in Kelud volcanic lake

Measurements of CO2 flux emitted at the surface of volcanic lakes have been performed using the so-called floating accumulation chamber method. Two statistical methods are used to process data: the graphical statistical and stochastic simulation methods. The results of graphical statistical approach allow the quantification of two degassing processes acting at the lake surface: one corresponding to CO2 fluxes resulting from rising bubbles and the second corresponding to equilibrium diffusion of dissolved CO2 at the water-air surface. The sequential Gaussian simulation method has been used for mapping the CO2 flux and estimating the total CO2 emission rate at the surface of volcanic lakes. The study of two volcanic lakes is presented in this chapter: Kelud, Indonesia and El Chichon, Mexico. Before a lava dome appeared in the middle of Kelud Lake on the 4th November 2007, the lake contained near neutral waters with a pH of 6. The total CO2 emission rate estimated by stochastic simulation ranged from 105 t day−1 for 2001 to 35 t day−1 for 2006. In early July 2007, the total flux for the lake area was estimated at 307 t day−1, showing that CO2 flux monitoring at the surface of volcanic lakes is a powerful tool in the improvement of early warning systems of volcanic eruptions. A significant change in CO2 flux was not detected for El Chichon lake during the period of survey (2007–2008) but the mapping of the CO2 flux on the lake area highlighted lineaments reflecting structures controlled by the main local and regional tectonic patterns.

Tropical peatlands play an important role in the global storage and cycling of carbon (C) but information on carbon dioxide (CO2) and methane (CH4) fluxes from these systems is sparse, particularly in the Neotropics. We quantified short and long-term temporal and small scale spatial variation in CO2 and CH4 fluxes from three contrasting vegetation communities in a domed ombrotrophic peatland in Panama. There was significant variation in CO2 fluxes among vegetation communities in the order Campnosperma panamensis > Raphia taedigera > Cyperus. There was no consistent variation among sites and no discernible seasonal pattern of CH4 flux despite the considerable range of values recorded (e.g. -1.0 to 12.6 mg m(-2) h(-1) in 2007). CO2 fluxes varied seasonally in 2007, being greatest in drier periods (300-400 mg m(-2) h(-1)) and lowest during the wet period (60-132 mg m(-2) h(-1)) while very high emissions were found during the 2009 wet period, suggesting that peak CO2 fluxes may occur following both low and high rainfall. In contrast, only weak relationships between CH4 flux and rainfall (positive at the C. panamensis site) and solar radiation (negative at the C. panamensis and Cyperus sites) was found. CO2 fluxes showed a diurnal pattern across sites and at the Cyperus sp. site CO2 and CH4 fluxes were positively correlated. The amount of dissolved carbon and nutrients were strong predictors of small scale within-site variability in gas release but the effect was site-specific. We conclude that (i) temporal variability in CO2 was greater than variation among vegetation communities; (ii) rainfall may be a good predictor of CO2 emissions from tropical peatlands but temporal variation in CH4 does not follow seasonal rainfall patterns; and (iii) diurnal variation in CO2 fluxes across different vegetation communities can be described by a Fourier model.

Carbon and oxygen dynamics in the Laurentian Great Lakes: Implications for the CO2 flux from terrestrial aquatic systems to the atmosphere

Here, we present the first detailed study on diffuse CO2 degassing in the lakes in the Western Group (Corvo and Flores islands) of the Azores archipelago. This research is of interest in order to determine (1) the overall CO2 emission from such lakes, as volcanic lakes are often underrepresented in the databases of these water bodies, and (2) the diffuse CO2 degassing estimates in active volcanic areas such as the Azores. The lake waters on Corvo and Flores islands are mainly of the Na–Cl type, which is likely caused by the lakes’ sea salt signatures, arising from nearby seawater spraying; however, a few samples show evidence of slight alkali earth metal and bicarbonate enrichments in the lake waters, suggesting a contribution of water–rock interaction. In this study, diffuse CO2 flux measurements were taken using the accumulation chamber method, and statistical analyses utilizing the graphical statistical approach (GSA) and sequential Gaussian simulation (sGs) were conducted on the CO2 flux data, showing that the CO2 flux values measured in these lakes were relatively low (0.0–18.6 g m−2 d−1). The results seem to indicate that there is a single source of CO2 (a biogenic source), which is also supported by the waters’ δ13C isotopic signatures. Significant differences in the final CO2 output values were verified between surveys (e.g., 0.16 t d−1 in R1; 0.32 t d−1 in R2), and these differences are probably associated with the monomictic character of the lakes. CO2 emissions ranged between 0.18 t d−1 (CE1) and 0.50 t d−1 (CW1) for the Corvo lakes and between 0.03 t d−1 (P1) and 0.32 t d−1 (R2) for the seven lakes studied on Flores Island. The presence of a dense macrophyte mass in a few of the lakes appears to enhance the CO2 flux in these lakes.

PDF HTML阅读 XML下载 导出引用 引用提醒 不同水生植物对景观水体CO2与CH4排放通量的影响 DOI: 10.5846/stxb202206281837 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(41807321);重庆市教委科学技术研究项目(KJZD-K202000502);大学生创新创业训练项目(202110637003) Effects of aquatic plants on the spatio-temporal variations of CO2 and CH4 fluxes in urban landscape waters Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:城市景观水体是大气CO2与CH4的排放热源,而水生植物作为景观水体的重要组成要素,对水体温室气体排放动态的影响并不清楚。选择重庆市观音塘国家湿地公园为研究区,利用漂浮箱法与顶空平衡法对观音塘水域7种不同水生植物分布区进行水-气界面CO2与CH4排放通量及CO2、CH4溶存浓度进行季节性监测,估算了植物传输对气体通量的贡献。结果表明:1)观音塘水体CO2与CH4浓度范围分别为8.0-341.8 μmol/L和0.23-5.26 μmol/L,排放通量分别为26.5-869.1 mmol m-2 d-1和0.40-11.15 mmol m-2 d-1,是大气净CO2与CH4排放源;2)观音塘开敞水区CO2与CH4排放通量低于大部分城市湖泊或景观水体,但植物覆盖区气体通量显著高于开敞水区,表明水生植物增强了景观水体温室气体排放;初步估算植物传输作用(非扩散通量)对水体CO2与CH4排放通量的贡献约为7.3%-44.6%与52.1%-63.4%,狐尾藻对CH4传输作用最强,睡莲、水葫芦次之,菖蒲、再力花、梭鱼草等挺水植物略低,苦草最弱,植物传输作用并未表现出明显的生活型差异;3)水体CO2与CH4浓度及排放通量季节变化显著,温暖季高于寒冷季,植物生长期变化与温度波动是主导水体CO2与CH4排放季节模式及变异强度的主要因素;4)水生植物覆盖区水体营养盐浓度、pH值、DO等因素与CO2、CH4排放通量呈显著的相关性,表明不同植物覆盖导致水生境的分异是影响水体CO2与CH4排放动态及变异性的重要机制。水生植物对水体温室气体产生、输移、排放等具有多重复杂机制,但总体增强了景观水体的温室气体通量,在未来城市水生态管理中应予以更多的关注。 Abstract:Urban landscape water is a hotspot of carbon dioxide (CO2) and (CH4) emissions to atmosphere, while little is known about the effect of aquatic plants, which is an important component of landscape water ecosystem, on greenhouse gas emissions dynamics in such water. In this study, we selected the Guanyin Pond National Wetland Park in Chongqing as a typical urban landscape water to carry out seasonal investigations for the fluxes and dissolved concentrations of CO2 and CH4 using floating chamber method and headspace method. The aims of this study were to explore contribution of aquatic plants to the spatio-temporal variations in aquatic CO2 and CH4 fluxes in urban landscape waters. The results showed that the concentrations of CO2 and CH4 ranged from 8.0-341.8 μmol/L to 0.23-5.26 μmol/L in Guanyin Pond, and the fluxes of CO2 and CH4 were ranging from 26.5 to 869.1 mmol m-2 d-1 and from 0.40 to 11.15 mmol m-2 d-1, respectively. Guanyin Pond was a net source of atmospheric CO2 and CH4. CO2 and CH4 fluxes in the open water area of Guanyin Pond were much lower than most of the reported values from ponds and lakes in urban area, while those in water area with aquatic vegetations distribution were much higher, indicating the aquatic plants enhanced the greenhouse gas emission of landscape water bodies. It was estimated that the plant transport contributed about 7.3%-44.6% and 52.1%-63.4% of total CO2 and CH4 fluxes from water-air surface, respectively. The contribution of plant transmission was different for different species despite no "biotype effect". The seasonal variations of CO2 and CH4 concentrations and fluxes in Guanyin Pond were significant with higher values in warm season and lower ones in cold season. We highlighted that the seasonal periodicity growth and temperature were main drivers for the seasonal patterns and variation intensity of CO2 and CH4 fluxes. Nutrients concentrations, pH and dissolved oxygen (DO) were influenced by aquatic vegetations distribution in Guanyin Pond, and were significantly correlated with CO2 and CH4 fluxes, indicating that the differentiation of water habitats caused by different aquatic plant species were important mechanism affecting the spatial variability of CO2 and CH4 dynamics. Despite mechanisms of aquatic plant impact on water CO2 and CH4 dynamics are complicated and various, aquatic plant distribution indeed enhance greenhouse gases fluxes of urban landscape water. Therefore, more attentions should be paid to the CO2 and CH4 dynamics in such special aquatic system in the future. 参考文献 相似文献 引证文献

This work constitutes the first floristic and ecological analysis of the phytoplankton community of a volcanic freshwater lake in Deception Island (62°57′S, 60°38′W, South Shetland Islands, Antarctica). The main limnological features and phytoplankton size fractions were analyzed. Samples were taken during the austral summer of 2002 at two opposite sites. According to ANOVA results performed with abiotic variables, no significant differences between sites were found. The phytoplankton community showed low algal species richness, with an important contribution of the tychoplanktonic taxa. In terms of species number, Bacillariophyceae was the dominant class. Autotrophic picoplankton registered the highest densities from the second sampling date onwards. Nanophytoplankton was represented by unidentified chrysophycean organisms, which showed different distribution patterns between sites. The net phytoplankton abundance remained low during the sampling period and was strongly correlated with chlorophyll a concentration. Both nutrient concentrations and chlorophyll a values indicated oligotrophic conditions.

The impact of permafrost on carbon dioxide and methane fluxes in Siberia: A meta-analysis

Effect of water-level fluctuations on methane and carbon dioxide dynamics in a shallow lake of Northern China: Implications for wetland restoration

The summer heat wave in 2018 led to the highest recorded water temperatures since 1926 – up to 21 C – in bottom coastal waters of the Baltic Sea, with implications for the respiration patterns in these shallow coastal systems. We applied cavity ring-down spectrometer measurements to continuously monitor carbon dioxide (CO2) and methane (CH4) surface-water concentrations, covering the coastal archipelagos of Sweden and Finland and the open and deeper parts of the Northern Baltic Proper. This allowed us to i) follow an upwelling event near the Swedish coast leading to elevated CO2 and moderate CH4 outgassing, and ii) to estimate CH4 sources and fluxes along the coast by investigating water column inventories and air-sea fluxes during a storm and an associated downwelling event. At the end of the heat wave, before the storm event, we found elevated CO2 (1583 µatm) and CH4 (70 nmol/L) concentrations. During the storm, a massive CO2 sea-air flux of up to 274 mmol m-2 d-1 was observed. While water-column CO2 concentrations were depleted during several hours of the storm, CH4 concentrations remained elevated. Overall, we found a positive relationship between CO2 and CH4 wind-driven sea-air fluxes, however, the highest CH4 fluxes were observed at low winds whereas highest CO2 fluxes were during peak winds, suggesting different sources and processes controlling their fluxes besides wind. We applied a box-model approach to estimate the CH4 supply needed to sustain these elevated CH4 concentrations and the results suggest a large source flux of CH4 to the water column of 2.5 mmol m-2 d-1. These results are qualitatively supported by acoustic observations of vigorous and widespread outgassing from the sediments, with flares that could be traced throughout the water column penetrating the pycnocline and reaching the sea surface. The results suggest that the heat wave triggered CO2 and CH4 fluxes in the coastal zones that are comparable with maximum emission rates found in other hot spots, such as boreal and arctic lakes and wetlands. Further, the results suggest that heat waves are as important for CO2 and CH4 sea-air fluxes as the ice break up in spring.

This study conducted a comprehensive assessment of the response of wetland ecosystems in temperate and polar latitudes, located on different continents, to extreme weather events. These events included temperature anomalies (unusually high/low temperatures) and precipitation anomalies (droughts/intense precipitation). The analysis of the response net ecosystem exchange (NEE) of CO2 and latent heat (LE) fluxes to extreme temperature and precipitation events used ERA5 reanalysis data [Smith, 2011] and observations of CO2 and LE fluxes from the global FLUXNET database [https://fluxnet.org/data/]. Fifteen greenhouse gas flux monitoring stations were selected for the study, representing the longest and most continuous time series of observations. These stations are located on different continents, with eight stations in temperate latitudes and seven in polar regions. It should be noted that this study focused exclusively on the warm season. The beginning and end of the warm season were defined as the sustained crossing of the daily mean air temperature above 0°C for at least seven consecutive days. For each station, daily anomalies of CO2 and LE fluxes were calculated as the deviation from the long-term mean values for the corresponding day of the year. Extremely high/low values of flux anomalies were identified as exceeding one standard deviation from the overall time series for each calendar month individually. To identify periods with extreme air temperature values, ERA5 reanalysis data on two-meter air temperature every 3 hours with a spatial resolution of 0.25°×0.25° from 1991 to 2021 were used. To estimate extreme precipitation amounts, data from half-hourly station observations were used. Daily means were calculated from these data in a first step. Thresholds for defining extremely hot/cold periods were calculated as daily mean air temperature exceeding the 95th percentile (for anomalously hot periods) or not exceeding the 5th percentile (for anomalously cold periods) of a normal distribution with mean and standard deviation. The distribution was constructed for a specific month of the year and then averaged over the entire period considered. Two approaches were used to determine the extreme precipitation threshold. In the first approach, extreme precipitation days were defined as days with daily precipitation exceeding the 95th percentile of the probability density function (the Weibull distribution was used for precipitation). The second approach was based on the assessment of the Antecedent Precipitation Index (API), which determines the cumulative effect of precipitation on CO2 fluxes. For the quantitative assessment of the relationship between temperature and precipitation extremes and flux anomalies, the percentages of days on which both the NEE/LE anomaly exceeded the standard deviation and the temperature/precipitation exceeded the 95th percentile for the upper threshold or the temperature did not reach the 5th percentile for the lower threshold were calculated. The percentage was calculated based on the total number of days when one of the characteristics (air temperature, daily sum of precipitation) exceeded the threshold. The analysis showed that temperate and polar wetland ecosystems can respond differently to temperature and precipitation anomalies. These differences can be attributed to the geographic location of the ecosystem, regional climatic conditions, plant species composition, and the intensity of temperature and precipitation extremes. During the warm half of the year, periods of extremely high temperatures in temperate latitudes were associated with a positive CO2 flux anomaly, corresponding to an increased emission of CO2 into the atmosphere. In contrast, polar latitudes showed an opposite response - an increase in CO2 uptake by wetland ecosystems under anomalously high temperatures. This opposite response of CO2 fluxes may be related to the different soil moisture regimes in polar wetland ecosystems and the different plant species composition. Extremely high temperatures were accompanied by positive LE anomalies due to the intensification of evaporation processes with rising temperatures, a trend observed in all wetland ecosystems analyzed. The immediate response of wetland ecosystems to intense precipitation (above the 95th percentile) was manifested as an increase in CO2 flux to the atmosphere at almost all stations analyzed. This observed response could be related to the "Birch effect" [Birch, 1964], which is characterized by an intensification of soil respiration due to a sudden increase in soil moisture and, consequently, an increase in the rate of decomposition and mineralization of organic matter during heavy precipitation and rising groundwater levels. LE flux decreases during intense precipitation, indicating suppression of evaporation due to high humidity and reduced incoming solar radiation. The cumulative effect (API index) of extremely high precipitation is characterized by a predominance of extremely positive CO2 flux anomalies over negative ones in wetland ecosystems at both temperate and polar latitudes. It should also be noted that the percentage of days with increased CO2 uptake during the two weeks following intense precipitation is significantly higher than for the immediate response (10-25% of days in temperate latitudes and 5-20% of days in polar latitudes). The increase in CO2 uptake after heavy precipitation may be related to enhanced photosynthetic rates of the vegetation cover under sunny weather and optimal soil moisture conditions. A prolonged absence of precipitation, represented by extremely low API values, is accompanied by negative CO2 flux anomalies (enhanced uptake) at most of the studied wetland ecosystem stations, indicating a high adaptive potential of the studied wetland ecosystems to short-term (less than 14 days) dry periods. On the other hand, enhanced CO2 uptake could be facilitated by clear weather conditions, which prevail during dry periods and are accompanied by an increase in direct solar radiation and corresponding acceleration of photosynthetic processes. It is noteworthy that flux anomalies often did not coincide with temperature or precipitation extremes, indicating that the functioning of wetland ecosystems is strongly influenced by multiple abiotic and biotic factors, which vary among different plant communities.

The decomposition of thawing permafrost organic matter (OM) to the greenhouse gases (GHG) carbon dioxide (CO2) and methane forms a positive feedback to global climate change. Data on in situ GHG fluxes from thawing permafrost OM are scarce and OM degradability is largely unknown, causing high uncertainties in the permafrost‐carbon climate feedback. We combined in situ CO2 and methane flux measurements at an abrupt permafrost thaw feature with laboratory incubations and dynamic modeling to quantify annual CO2 release from thawing permafrost OM, estimate its in situ degradability and evaluate the explanatory power of incubation experiments. In July 2016 and 2019, CO2 fluxes ranged between 0.24 and 2.6 g CO2‐C m−2 d−1. Methane fluxes were low, which coincided with the absence of active methanogens in the Pleistocene permafrost. CO2 fluxes were lower three years after initial thaw after normalizing these fluxes to thawed carbon, indicating the depletion of labile carbon. Higher CO2 fluxes from thawing Pleistocene permafrost than from Holocene permafrost indicate OM preservation for millennia and give evidence that microbial activity in the permafrost was not substantial. Short‐term incubations overestimated in situ CO2 fluxes but underestimated methane fluxes. Two independent models simulated median annual CO2 fluxes of 160 and 184 g CO2‐C m−2 from the thaw slump, which include 25%–31% CO2 emissions during winter. Annual CO2 fluxes represent 0.8% of the carbon pool thawed in the surface soil. Our results demonstrate the potential of abrupt thaw processes to transform the tundra from carbon neutral into a substantial GHG source.

Sulfide is a crucial parameter in volcanic lakes, as its levels and fluctuations in the lake determine the origin of sulfide and the extent of its impact on the lake ecosystem. In stratified lakes, the sulfide produced tends to be retained beneath the oxic layer. The sulfides rise towards the surface as the oxic layer thins triggered by decreased water column thermal stratification. Meanwhile, the strength or weakness of thermal stratification is greatly influenced by weather conditions. Lake Maninjau is a volcanic lake with a relatively high sulfide content. Its vertical distribution in the water column is highly dependent on the stratification of the water column. When stratification disappears, sulfide rises to the surface (locally known as tubo belerang) and has a negative impact on surface biota. The objective of this study is to examine the distribution of sulfides in the water column of Lake Maninjau under two different weather conditions. We perform two surveys to measure physicochemical parameters and sulfide concentration on 26‒29 November 2022 and 25‒26 August 2023 considering the seasonal pattern. We found that air temperatures and sunshine duration combined with precipitation and wind speed drive the thermal stratification of the water column. The lower air temperature, shorter sunshine duration, higher precipitation, and stronger wind speed in the first survey (west monsoon) compared with the second survey (east monsoon) resulted in lower stratification and triggered the elevated sulfide to the surface. In the middle of the lake, the surface sulfide measured during the first survey was 4.16 µg/L. Meanwhile, in the second survey, it was only observed at 1.16 µg/L. The distribution of sulfides within the water column of Lake Maninjau is regulated by the stratification of the water column, a process directly impacted by weather conditions.

This study was conducted to evaluate the impacts of N fertilizer and landscape position on carbon dioxide (CO2) and methane (CH4) fluxes from a US Northern Great Plains landscape seeded to switchgrass (Panicum virgatum L.). The experimental design included three N levels (low, 0 kg N ha−1; medium, 56 kg N ha−1; and high, 112 kg N ha−1) replicated four times. The experiment was repeated at shoulder and footslope positions. Soil CO2 and CH4 fluxes were monitored once every 2 weeks from May 2010 to October 2012. The CO2 fluxes were 40% higher at the footslope than the shoulder landscape position, and CH4 fluxes were similar in both landscape positions. Soil CO2 and CH4 fluxes averaged over the sampling dates were not impacted by N rates. Seasonal variations showed highest CO2 release and CH4 uptake in summer and fall, likely due to warmer and moist soil conditions. Higher CH4 release was observed in winter possibly due to increased anaerobic conditions. However, year to year (2010–2012) variations in soil CO2 and CH4 fluxes were more pronounced than the variations due to the impact of landscape positions and N rates. Drought conditions reported in 2012, with higher annual temperature and lower soil moisture than long‐term average, resulted in higher summer and fall CO2 fluxes (between 1.3 and 3 times) than in 2011 and 2010. These conditions also promoted a net CH4 uptake in 2012 in comparison to 2010 when there was net CH4 release. Results from this study conclude that landscape positions, air temperature, and soil moisture content strongly influenced soil CO2 fluxes, whereas soil moisture impacted the direction of CH4 fluxes (uptake or release). However, a comprehensive life cycle analysis would be appropriate to evaluate environmental impacts associated with switchgrass production under local environmental conditions.

Context Conversion of grasslands to croplands can usually result in the degradation of soils and increased greenhouse gas (GHG) emissions such as carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4). However, little is known about the impacts of grassland conversion to recently tilled croplands on soils and GHG fluxes. Aims A field experiment was established in 2016 to evaluate the impacts of grassland conversion to tilled cropland under different landscape positions (upslope, backslope, and footslope) on select soil properties and soil GHG fluxes. Key results The findings showed that the grassland conversion significantly increased soil bulk density and electrical conductivity but reduced pH and total nitrogen (TN). The conversion impacted soil biome community grassland and tilled croplands. The landscape position significantly impacted soil pH (footslope < upslope) and TN (footslope > upslope). The grassland conversion significantly decreased soil CO2 fluxes, but increased soil CH4 and N2O fluxes. The landscape position significantly impacted soil CO2 (footslope > upslope and backslope) and CH4 (upslope > footslope and backslope) fluxes for some periods. Soil CO2 and N2O fluxes generally followed upward and downward trends over time, respectively. Conclusions These results indicate that grassland conversion was able to lose soil N, increase soil compaction, acidity, salts, and soil N2O and CH4 fluxes, and decrease the diversity of abundant genera and CO2 fluxes. Footslope increased TN, soil acidity, CO2, and CH4 fluxes, compared with upslope and backslope. CO2 fluxes under grassland and tilled cropland significantly increased over time, whereas N2O fluxes under grassland significantly reduced. Implications Conversion of grassland to tilled cropland significantly impacted on sol quality. It caused a loss in soil N and increased soil compaction, acidity and salts. Grassland conversion also decreased the abundance and diversity soil microbiome.

Seasonal changes in the spatial structures of N2O, CO2, and CH4 fluxes from Acacia mangium plantation soils in Indonesia