Louise C. V. Rewrie, B. Baschek, J. V. van Beusekom, A. Körtzinger, G. Ollesch, Y. Voynova
Abstract. Estuaries are an important contributor to the global carbon budget, facilitating carbon removal, transfer, and transformation between land and the coastal ocean. Estuaries are susceptible to global climate change and anthropogenic perturbations. We find that a long-term significant mid-estuary increase in dissolved inorganic carbon (DIC) of 6–21 µmol kg−1 yr−1 (1997–2020) in a temperate estuary in Germany (Elbe Estuary) was driven by an increase in upper-estuary particulate organic carbon (POC) content of 8–14 µmol kg−1 yr−1. The temporal POC increase was due to an overall improvement in water quality observed in the form of high rates of primary production and a significant drop in biological oxygen demand. The magnitude of mid-estuary DIC gain was equivalent to the increased POC production in the upper estuary, suggesting that POC is effectively remineralized and retained as DIC in the mid-estuary, with the estuary acting as an efficient natural filter for POC. In the context of this significant long-term DIC increase, a recent extended drought period (2014–2020) significantly lowered the annual mean river discharge (468 ± 234 m3 s−1) compared to the long-term mean (690 ± 441 m3 s−1, 1960–2020), while the late spring internal DIC load in the estuary doubled. The drought induced a longer dry season, starting in May (earlier than normal), increased the residence time in the estuary and allowed for a more complete remineralization period of POC. Annually, 77 %–94 % of the total DIC export was laterally transported to the coastal waters, reaching 89 ± 4.8 Gmol C yr−1, and thus, between 1997 and 2020, only an estimated maximum of 23 % (10 Gmol C yr−1) was released via carbon dioxide (CO2) evasion. Export of DIC to coastal waters decreased significantly during the drought, on average by 24 % (2014–2020: 38 ± 5.4 Gmol C yr−1), compared to the non-drought period. In contrast, there was no change in the water–air CO2 flux during the drought. We have identified that seasonal changes in DIC processing in an estuary require consideration when estimating both the long-term and future changes in water–air CO2 flux and DIC export to coastal waters. Regional and global carbon budgets should therefore take into account carbon cycling estimates in estuaries, as well as their changes over time in relation to impacts of water quality changes and extreme hydrological events.
{"title":"Recent inorganic carbon increase in a temperate estuary driven by water quality improvement and enhanced by droughts","authors":"Louise C. V. Rewrie, B. Baschek, J. V. van Beusekom, A. Körtzinger, G. Ollesch, Y. Voynova","doi":"10.5194/bg-20-4931-2023","DOIUrl":"https://doi.org/10.5194/bg-20-4931-2023","url":null,"abstract":"Abstract. Estuaries are an important contributor to the global carbon budget, facilitating carbon removal, transfer, and transformation between land and the coastal ocean. Estuaries are susceptible to global climate change and anthropogenic perturbations. We find that a long-term significant mid-estuary increase in dissolved inorganic carbon (DIC) of 6–21 µmol kg−1 yr−1 (1997–2020) in a temperate estuary in Germany (Elbe Estuary) was driven by an increase in upper-estuary particulate organic carbon (POC) content of 8–14 µmol kg−1 yr−1. The temporal POC increase was due to an overall improvement in water quality observed in the form of high rates of primary production and a significant drop in biological oxygen demand. The magnitude of mid-estuary DIC gain was equivalent to the increased POC production in the upper estuary, suggesting that POC is effectively remineralized and retained as DIC in the mid-estuary, with the estuary acting as an efficient natural filter for POC. In the context of this significant long-term DIC increase, a recent extended drought period (2014–2020) significantly lowered the annual mean river discharge (468 ± 234 m3 s−1) compared to the long-term mean (690 ± 441 m3 s−1, 1960–2020), while the late spring internal DIC load in the estuary doubled. The drought induced a longer dry season, starting in May (earlier than normal), increased the residence time in the estuary and allowed for a more complete remineralization period of POC. Annually, 77 %–94 % of the total DIC export was laterally transported to the coastal waters, reaching 89 ± 4.8 Gmol C yr−1, and thus, between 1997 and 2020, only an estimated maximum of 23 % (10 Gmol C yr−1) was released via carbon dioxide (CO2) evasion. Export of DIC to coastal waters decreased significantly during the drought, on average by 24 % (2014–2020: 38 ± 5.4 Gmol C yr−1), compared to the non-drought period. In contrast, there was no change in the water–air CO2 flux during the drought. We have identified that seasonal changes in DIC processing in an estuary require consideration when estimating both the long-term and future changes in water–air CO2 flux and DIC export to coastal waters. Regional and global carbon budgets should therefore take into account carbon cycling estimates in estuaries, as well as their changes over time in relation to impacts of water quality changes and extreme hydrological events.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":"92 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138975521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mutong Niu, Shu Huang, Wei Hu, Yajie Wang, Wanyun Xu, Wan Wei, Qian Zhang, Zihan, Wang, Donghuan Zhang, Rui Jin, Libin Wu, Junjun Deng, Fangxia Shen, P. Fu
Abstract. Bioaerosols play significant roles in causing health and climate effects. Sugar compounds in air have been widely used to trace the source of bioaerosols. However, knowledge about the association of sugar molecules and the microbial community at taxonomic levels in atmospheric aerosols remains limited. Here, microbial community compositions and sugar molecules in total suspended particles collected from a typical rural site, Gucheng, in the North China Plain were investigated by gas chromatography–mass spectrometry and high-throughput gene sequencing, respectively. Results show that fungal community structure exhibited distinct diurnal variation with largely enhanced contribution of Basidiomycota at night, while bacterial community structure showed no obvious difference between daytime and night. SourceTracker analysis revealed that fungi and bacteria were mainly from plant leaves and unresolved sources (presumably human-related emissions and/or long-distance transport). All the detected anhydrosugars and sugar alcohols and trehalose showed diurnal variations with lower concentrations in the daytime and higher concentrations at night, which may be affected by enhanced fungal emissions at night, while primary sugars (except trehalose) showed an opposite trend. Mantel's test showed that more sugar compounds exhibited significant associations with fungal community structure than bacterial community structure. Co-occurrence analysis revealed the strong associations between sugar compounds and a few saprophytic fungal genera with low relative abundances, e.g., Hannaella, Lectera, Peniophora, Hydnophlebia, Sporobolomyces and Cyphellophora. This study suggests that the entire fungal community, rather than specific fungal taxa, likely greatly contributes to sugar compounds in rural aerosols, while the contribution of bacteria is limited.
{"title":"Characteristics of bacterial and fungal communities and their associations with sugar compounds in atmospheric aerosols at a rural site in northern China","authors":"Mutong Niu, Shu Huang, Wei Hu, Yajie Wang, Wanyun Xu, Wan Wei, Qian Zhang, Zihan, Wang, Donghuan Zhang, Rui Jin, Libin Wu, Junjun Deng, Fangxia Shen, P. Fu","doi":"10.5194/bg-20-4915-2023","DOIUrl":"https://doi.org/10.5194/bg-20-4915-2023","url":null,"abstract":"Abstract. Bioaerosols play significant roles in causing health and climate effects. Sugar compounds in air have been widely used to trace the source of bioaerosols. However, knowledge about the association of sugar molecules and the microbial community at taxonomic levels in atmospheric aerosols remains limited. Here, microbial community compositions and sugar molecules in total suspended particles collected from a typical rural site, Gucheng, in the North China Plain were investigated by gas chromatography–mass spectrometry and high-throughput gene sequencing, respectively. Results show that fungal community structure exhibited distinct diurnal variation with largely enhanced contribution of Basidiomycota at night, while bacterial community structure showed no obvious difference between daytime and night. SourceTracker analysis revealed that fungi and bacteria were mainly from plant leaves and unresolved sources (presumably human-related emissions and/or long-distance transport). All the detected anhydrosugars and sugar alcohols and trehalose showed diurnal variations with lower concentrations in the daytime and higher concentrations at night, which may be affected by enhanced fungal emissions at night, while primary sugars (except trehalose) showed an opposite trend. Mantel's test showed that more sugar compounds exhibited significant associations with fungal community structure than bacterial community structure. Co-occurrence analysis revealed the strong associations between sugar compounds and a few saprophytic fungal genera with low relative abundances, e.g., Hannaella, Lectera, Peniophora, Hydnophlebia, Sporobolomyces and Cyphellophora. This study suggests that the entire fungal community, rather than specific fungal taxa, likely greatly contributes to sugar compounds in rural aerosols, while the contribution of bacteria is limited.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":"27 17","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138975061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carrie L. Thomas, B. Jansen, S. Czerwiński, M. Gałka, K. Knorr, E., E. V. Loon, M. Egli, G. Wiesenberg
Abstract. As peatlands are a major terrestrial sink in the global carbon cycle, gaining an understanding of their development and changes throughout time is essential in order to predict their future carbon budget and potentially mitigate the adverse outcomes of climate change. With this aim to understand peat development, many studies have investigated the paleoecological dynamics by analyzing various proxies, including pollen, macrofossil, elemental, and biomarker analyses. However, as each of these proxies is known to have its own benefits and limitations, examining them in parallel allows for a deeper understanding of these paleoecological dynamics at the peatland and a systematic comparison of the power of these individual proxies. In this study, we therefore analyzed peat cores from a peatland in Germany (Beerberg, Thuringia) to (a) characterize the vegetation dynamics over the course of the peatland development during the late Holocene and (b) evaluate to what extent the inclusion of multiple proxies, specifically pollen, plant macrofossils, and biomarkers, contributes to a deeper understanding of those dynamics and interaction among factors. We found that, despite a major shift in the regional forest composition from primarily beech to spruce as well as many indicators of human impact in the region, the local plant population in the Beerberg area remained stable over time following the initial phase of peatland development up until the last couple of centuries. Therefore, little variation could be derived from the paleobotanical data alone. The combination of pollen and macrofossil analyses with the elemental and biomarker analyses enabled further understanding of the site development as these proxies added valuable additional information, including the occurrence of climatic variations, such as the Little Ice Age, and more recent disturbances, such as drainage.
{"title":"Comparison of paleobotanical and biomarker records of mountain peatland and forest ecosystem dynamics over the last 2600 years in central Germany","authors":"Carrie L. Thomas, B. Jansen, S. Czerwiński, M. Gałka, K. Knorr, E., E. V. Loon, M. Egli, G. Wiesenberg","doi":"10.5194/bg-20-4893-2023","DOIUrl":"https://doi.org/10.5194/bg-20-4893-2023","url":null,"abstract":"Abstract. As peatlands are a major terrestrial sink in the global carbon cycle, gaining an understanding of their development and changes throughout time is essential in order to predict their future carbon budget and potentially mitigate the adverse outcomes of climate change. With this aim to understand peat development, many studies have investigated the paleoecological dynamics by analyzing various proxies, including pollen, macrofossil, elemental, and biomarker analyses. However, as each of these proxies is known to have its own benefits and limitations, examining them in parallel allows for a deeper understanding of these paleoecological dynamics at the peatland and a systematic comparison of the power of these individual proxies. In this study, we therefore analyzed peat cores from a peatland in Germany (Beerberg, Thuringia) to (a) characterize the vegetation dynamics over the course of the peatland development during the late Holocene and (b) evaluate to what extent the inclusion of multiple proxies, specifically pollen, plant macrofossils, and biomarkers, contributes to a deeper understanding of those dynamics and interaction among factors. We found that, despite a major shift in the regional forest composition from primarily beech to spruce as well as many indicators of human impact in the region, the local plant population in the Beerberg area remained stable over time following the initial phase of peatland development up until the last couple of centuries. Therefore, little variation could be derived from the paleobotanical data alone. The combination of pollen and macrofossil analyses with the elemental and biomarker analyses enabled further understanding of the site development as these proxies added valuable additional information, including the occurrence of climatic variations, such as the Little Ice Age, and more recent disturbances, such as drainage.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":"46 15","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139006987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Langlet, F. Mermillod‐Blondin, Noémie Deldicq, A. Bauville, Gwendoline Duong, L. Konecny, M. Hugoni, L. Denis, V. Bouchet
Abstract. Bioturbation processes influence particulate (sediment reworking) and dissolved (bioirrigation) fluxes at the sediment–water interface. Recent works showed that benthic foraminifera largely contribute to sediment reworking in intertidal mudflats, yet their role in bioirrigation processes remains unknown. In a laboratory experiment, we showed that foraminifera motion behaviour increased the oxygen penetration depth and decreased the total organic content. Their activity in the top 5 mm of the sediment also affected prokaryotic community structure. Indeed, in bioturbated sediment, bacterial richness was reduced, and sulfate-reducing taxa abundance in deeper layers was also reduced, probably inhibited by the larger oxygen penetration depth. Since foraminifera can modify both particulate and dissolved fluxes, their role as bioturbators can no longer be neglected. They are further able to mediate the prokaryotic community, suggesting that they play a major role in the benthic ecosystem functioning and may be the first described single-celled eukaryotic ecosystem engineers.
{"title":"Single-celled bioturbators: benthic foraminifera mediate oxygen penetration and prokaryotic diversity in intertidal sediment","authors":"D. Langlet, F. Mermillod‐Blondin, Noémie Deldicq, A. Bauville, Gwendoline Duong, L. Konecny, M. Hugoni, L. Denis, V. Bouchet","doi":"10.5194/bg-20-4875-2023","DOIUrl":"https://doi.org/10.5194/bg-20-4875-2023","url":null,"abstract":"Abstract. Bioturbation processes influence particulate (sediment reworking) and dissolved (bioirrigation) fluxes at the sediment–water interface. Recent works showed that benthic foraminifera largely contribute to sediment reworking in intertidal mudflats, yet their role in bioirrigation processes remains unknown. In a laboratory experiment, we showed that foraminifera motion behaviour increased the oxygen penetration depth and decreased the total organic content. Their activity in the top 5 mm of the sediment also affected prokaryotic community structure. Indeed, in bioturbated sediment, bacterial richness was reduced, and sulfate-reducing taxa abundance in deeper layers was also reduced, probably inhibited by the larger oxygen penetration depth. Since foraminifera can modify both particulate and dissolved fluxes, their role as bioturbators can no longer be neglected. They are further able to mediate the prokaryotic community, suggesting that they play a major role in the benthic ecosystem functioning and may be the first described single-celled eukaryotic ecosystem engineers.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":"59 18","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138587361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Jauhiainen, Juha Heikkinen, Nicholas Clarke, Hongxing He, Lise Dalsgaard, K. Minkkinen, P. Ojanen, L. Vesterdal, Jukka Alm, A. Butlers, I. Callesen, Sabine Jordan, A. Lohila, Ü. Mander, H. Óskarsson, B. Sigurdsson, Gunnhild Søgaard, K. Soosaar, Å. Kasimir, B. Bjarnadóttir, A. Lazdiņš, R. Laiho
Abstract. We compiled published peer-reviewed CO2, CH4, and N2O data on managed drained organic forest soils in boreal and temperate zones to revisit the current Tier 1 default emission factors (EFs) provided in the IPCC (2014) Wetlands Supplement: to see whether their uncertainty may be reduced; to evaluate possibilities for breaking the broad categories used for the IPCC EFs into more site-type-specific ones; and to inspect the potential relevance of a number of environmental variables for predicting the annual soil greenhouse gas (GHG) balances, on which the EFs are based. Despite a considerable number of publications applicable for compiling EFs being added, only modest changes were found compared to the Tier 1 default EFs. However, the more specific site type categories generated in this study showed narrower confidence intervals compared to the default categories. Overall, the highest CO2 EFs were found for temperate afforested agricultural lands and boreal forestry-drained sites with very low tree stand productivity. The highest CH4 EFs in turn prevailed in boreal nutrient-poor forests with very low tree stand productivity and temperate forests irrespective of nutrient status, while the EFs for afforested sites were low or showed a sink function. The highest N2O EFs were found for afforested agricultural lands and forestry-drained nutrient-rich sites. The occasional wide confidence intervals could be mainly explained by single or a few highly deviating estimates rather than the broadness of the categories applied. Our EFs for the novel categories were further supported by the statistical models connecting the annual soil GHG balances to site-specific soil nutrient status indicators, tree stand characteristics, and temperature-associated weather and climate variables. The results of this synthesis have important implications for EF revisions and national emission reporting, e.g. by the use of different categories for afforested sites and forestry-drained sites, and more specific site productivity categories based on timber production potential.
{"title":"Reviews and syntheses: Greenhouse gas emissions from drained organic forest soils – synthesizing data for site-specific emission factors for boreal and cool temperate regions","authors":"J. Jauhiainen, Juha Heikkinen, Nicholas Clarke, Hongxing He, Lise Dalsgaard, K. Minkkinen, P. Ojanen, L. Vesterdal, Jukka Alm, A. Butlers, I. Callesen, Sabine Jordan, A. Lohila, Ü. Mander, H. Óskarsson, B. Sigurdsson, Gunnhild Søgaard, K. Soosaar, Å. Kasimir, B. Bjarnadóttir, A. Lazdiņš, R. Laiho","doi":"10.5194/bg-20-4819-2023","DOIUrl":"https://doi.org/10.5194/bg-20-4819-2023","url":null,"abstract":"Abstract. We compiled published peer-reviewed CO2, CH4, and N2O data on managed drained organic forest soils in boreal and temperate zones to revisit the current Tier 1 default emission factors (EFs) provided in the IPCC (2014) Wetlands Supplement: to see whether their uncertainty may be reduced; to evaluate possibilities for breaking the broad categories used for the IPCC EFs into more site-type-specific ones; and to inspect the potential relevance of a number of environmental variables for predicting the annual soil greenhouse gas (GHG) balances, on which the EFs are based. Despite a considerable number of publications applicable for compiling EFs being added, only modest changes were found compared to the Tier 1 default EFs. However, the more specific site type categories generated in this study showed narrower confidence intervals compared to the default categories. Overall, the highest CO2 EFs were found for temperate afforested agricultural lands and boreal forestry-drained sites with very low tree stand productivity. The highest CH4 EFs in turn prevailed in boreal nutrient-poor forests with very low tree stand productivity and temperate forests irrespective of nutrient status, while the EFs for afforested sites were low or showed a sink function. The highest N2O EFs were found for afforested agricultural lands and forestry-drained nutrient-rich sites. The occasional wide confidence intervals could be mainly explained by single or a few highly deviating estimates rather than the broadness of the categories applied. Our EFs for the novel categories were further supported by the statistical models connecting the annual soil GHG balances to site-specific soil nutrient status indicators, tree stand characteristics, and temperature-associated weather and climate variables. The results of this synthesis have important implications for EF revisions and national emission reporting, e.g. by the use of different categories for afforested sites and forestry-drained sites, and more specific site productivity categories based on timber production potential.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":"16 10","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138591581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Using satellite sea surface temperature (SST) and chlorophyll a (Chl a) as well as observation-based reconstruction of dissolved inorganic carbon (DIC) and partial pressure of CO2 (pCO2) from 1996 to 2015, we investigate the modulation mechanisms of eddies on surface physical and biogeochemical parameters in the Southern Ocean (SO). About one-quarter of eddies are observed to be “abnormal” (cold anticyclonic and warm cyclonic eddies) in the SO, which show opposite SST signatures to “normal” eddies (warm anticyclonic and cold cyclonic eddies). The study finds that the modification of abnormal eddies on physical and biogeochemical parameters is significant and differs from normal eddies due to the combined effects of eddy pumping and eddy-induced Ekman pumping. Normal and abnormal eddies have opposite DIC anomalies, contrary to the SST anomalies. Moreover, the contributions of abnormal eddies to pCO2 are about 2.7 times higher than normal eddies in regions where abnormal eddies dominate. Although Chl a anomalies in normal and abnormal eddies show similar patterns and signals, eddy-induced Ekman pumping attenuates the magnitudes of Chl a anomalies within abnormal eddies. In addition to the variation of the same parameter within different eddies, the dominant eddy-driven mechanisms for different parameters within the same kind of eddies also vary. The strength of the eddy stirring effect on different parameters is the primary factor causing these differences, attributed to variations in the magnitudes of horizontal parameter gradients. Understanding the role of abnormal eddies and the complexity of eddy-driven processes is crucial for accurately estimating the influence of mesoscale eddies on physical and biogeochemical processes in the SO, which is essential for simulating and predicting biogeochemical dynamics and carbon cycling in the region.
{"title":"Characteristics of surface physical and biogeochemical parameters within mesoscale eddies in the Southern Ocean","authors":"Qian Liu, Yingjie Liu, Xiaofen Li","doi":"10.5194/bg-20-4857-2023","DOIUrl":"https://doi.org/10.5194/bg-20-4857-2023","url":null,"abstract":"Abstract. Using satellite sea surface temperature (SST) and chlorophyll a (Chl a) as well as observation-based reconstruction of dissolved inorganic carbon (DIC) and partial pressure of CO2 (pCO2) from 1996 to 2015, we investigate the modulation mechanisms of eddies on surface physical and biogeochemical parameters in the Southern Ocean (SO). About one-quarter of eddies are observed to be “abnormal” (cold anticyclonic and warm cyclonic eddies) in the SO, which show opposite SST signatures to “normal” eddies (warm anticyclonic and cold cyclonic eddies). The study finds that the modification of abnormal eddies on physical and biogeochemical parameters is significant and differs from normal eddies due to the combined effects of eddy pumping and eddy-induced Ekman pumping. Normal and abnormal eddies have opposite DIC anomalies, contrary to the SST anomalies. Moreover, the contributions of abnormal eddies to pCO2 are about 2.7 times higher than normal eddies in regions where abnormal eddies dominate. Although Chl a anomalies in normal and abnormal eddies show similar patterns and signals, eddy-induced Ekman pumping attenuates the magnitudes of Chl a anomalies within abnormal eddies. In addition to the variation of the same parameter within different eddies, the dominant eddy-driven mechanisms for different parameters within the same kind of eddies also vary. The strength of the eddy stirring effect on different parameters is the primary factor causing these differences, attributed to variations in the magnitudes of horizontal parameter gradients. Understanding the role of abnormal eddies and the complexity of eddy-driven processes is crucial for accurately estimating the influence of mesoscale eddies on physical and biogeochemical processes in the SO, which is essential for simulating and predicting biogeochemical dynamics and carbon cycling in the region.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":"52 3","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138591136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. A. Faelga, L. Cantelli, S. Silvestri, B. Giambastiani
Abstract. Unoccupied aerial vehicle (UAV) monitoring surveys are used to assess a dune restoration project in the protected natural area of the Bevano River mouth on the northern Adriatic coast (Ravenna, Italy). The impacts of the installed fences to aid dune development are quantified in terms of sand volume and vegetation cover changes over 5 years using a systematic data processing workflow based on structure-from-motion (SfM) photogrammetry and the Geomorphic Change Detection (GCD) toolset applied to two drone surveys in 2016 and 2021. Accuracy assessment is performed using statistical analysis between ground-truth and model elevation data. Results show that the fence proves to be effective in promoting recovery and growth since significant sand deposition was observed along the dune foot and front – a total area of 3799 m2, volume of 1109 m3, and average depositional depth of 0.29 m. Progradation of around 3–5 m of the foredune and embryo development were also evident. There was a decrease in blowout features of about 155 m2 due to increased deposition and vegetation colonization. There was also an average percent increase of 160 % on wave-induced driftwood and/or debris along the beach and of 9.6 % vegetation within the fence based on the cover analysis on selected transects. Erosion of around 1439 m2 is apparent mostly at the northern portion of the structure, which could be accounted for by the aerodynamic and morphodynamic conditions around the fence and its configuration to trap sediments and efficiency in doing so. Overall, dune fencing coupled with limiting debris cleaning along the protected coast was effective. The proposed workflow can aid in creating transferable guidelines to stakeholders in integrated coastal zone management (ICZM) implementation on Mediterranean low-lying sandy coasts.
{"title":"Dune belt restoration effectiveness assessed by UAV topographic surveys (northern Adriatic coast, Italy)","authors":"R. A. Faelga, L. Cantelli, S. Silvestri, B. Giambastiani","doi":"10.5194/bg-20-4841-2023","DOIUrl":"https://doi.org/10.5194/bg-20-4841-2023","url":null,"abstract":"Abstract. Unoccupied aerial vehicle (UAV) monitoring surveys are used to assess a dune restoration project in the protected natural area of the Bevano River mouth on the northern Adriatic coast (Ravenna, Italy). The impacts of the installed fences to aid dune development are quantified in terms of sand volume and vegetation cover changes over 5 years using a systematic data processing workflow based on structure-from-motion (SfM) photogrammetry and the Geomorphic Change Detection (GCD) toolset applied to two drone surveys in 2016 and 2021. Accuracy assessment is performed using statistical analysis between ground-truth and model elevation data. Results show that the fence proves to be effective in promoting recovery and growth since significant sand deposition was observed along the dune foot and front – a total area of 3799 m2, volume of 1109 m3, and average depositional depth of 0.29 m. Progradation of around 3–5 m of the foredune and embryo development were also evident. There was a decrease in blowout features of about 155 m2 due to increased deposition and vegetation colonization. There was also an average percent increase of 160 % on wave-induced driftwood and/or debris along the beach and of 9.6 % vegetation within the fence based on the cover analysis on selected transects. Erosion of around 1439 m2 is apparent mostly at the northern portion of the structure, which could be accounted for by the aerodynamic and morphodynamic conditions around the fence and its configuration to trap sediments and efficiency in doing so. Overall, dune fencing coupled with limiting debris cleaning along the protected coast was effective. The proposed workflow can aid in creating transferable guidelines to stakeholders in integrated coastal zone management (ICZM) implementation on Mediterranean low-lying sandy coasts.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":"48 5","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138592082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. De Pue, S. Wieneke, A. Bastos, J. Barrios, Liyang Liu, P. Ciais, A. Arboleda, R. Hamdi, M. Maleki, F. Maignan, F. Gellens-Meulenberghs, I. Janssens, M. Balzarolo
Abstract. The gross primary production (GPP) of the terrestrial biosphere is a key source of variability in the global carbon cycle. It is modulated by hydrometeorological drivers (i.e. short-wave radiation, air temperature, vapour pressure deficit and soil moisture) and the vegetation state (i.e. canopy greenness, leaf area index) at instantaneous to interannual timescales. In this study, we set out to evaluate the ability of GPP models to capture this variability. Eleven models were considered, which rely purely on remote sensing data (RS-driven), meteorological data (meteo-driven, e.g. dynamic global vegetation models; DGVMs) or a combination of both (hybrid, e.g. light-use efficiency, LUE, models). They were evaluated using in situ observations at 61 eddy covariance sites, covering a broad range of herbaceous and forest biomes. The results illustrated how the determinant of temporal variability shifts from meteorological variables at sub-seasonal timescales to biophysical variables at seasonal and interannual timescales. RS-driven models lacked the sensitivity to the dominant drivers at short timescales (i.e. short-wave radiation and vapour pressure deficit) and failed to capture the decoupling of photosynthesis and canopy greenness (e.g. in evergreen forests). Conversely, meteo-driven models accurately captured the variability across timescales, despite the challenges in the prognostic simulation of the vegetation state. The largest errors were found in water-limited sites, where the accuracy of the soil moisture dynamics determines the quality of the GPP estimates. In arid herbaceous sites, canopy greenness and photosynthesis were more tightly coupled, resulting in improved results with RS-driven models. Hybrid models capitalized on the combination of RS observations and meteorological information. LUE models were among the most accurate models to monitor GPP across all biomes, despite their simple architecture. Overall, we conclude that the combination of meteorological drivers and remote sensing observations is required to yield an accurate reproduction of the spatio-temporal variability of GPP. To further advance the performance of DGVMs, improvements in the soil moisture dynamics and vegetation evolution are needed.
{"title":"Temporal variability of observed and simulated gross primary productivity, modulated by vegetation state and hydrometeorological drivers","authors":"J. De Pue, S. Wieneke, A. Bastos, J. Barrios, Liyang Liu, P. Ciais, A. Arboleda, R. Hamdi, M. Maleki, F. Maignan, F. Gellens-Meulenberghs, I. Janssens, M. Balzarolo","doi":"10.5194/bg-20-4795-2023","DOIUrl":"https://doi.org/10.5194/bg-20-4795-2023","url":null,"abstract":"Abstract. The gross primary production (GPP) of the terrestrial biosphere is a key source of variability in the global carbon cycle. It is modulated by hydrometeorological drivers (i.e. short-wave radiation, air temperature, vapour pressure deficit and soil moisture) and the vegetation state (i.e. canopy greenness, leaf area index) at instantaneous to interannual timescales. In this study, we set out to evaluate the ability of GPP models to capture this variability. Eleven models were considered, which rely purely on remote sensing data (RS-driven), meteorological data (meteo-driven, e.g. dynamic global vegetation models; DGVMs) or a combination of both (hybrid, e.g. light-use efficiency, LUE, models). They were evaluated using in situ observations at 61 eddy covariance sites, covering a broad range of herbaceous and forest biomes. The results illustrated how the determinant of temporal variability shifts from meteorological variables at sub-seasonal timescales to biophysical variables at seasonal and interannual timescales. RS-driven models lacked the sensitivity to the dominant drivers at short timescales (i.e. short-wave radiation and vapour pressure deficit) and failed to capture the decoupling of photosynthesis and canopy greenness (e.g. in evergreen forests). Conversely, meteo-driven models accurately captured the variability across timescales, despite the challenges in the prognostic simulation of the vegetation state. The largest errors were found in water-limited sites, where the accuracy of the soil moisture dynamics determines the quality of the GPP estimates. In arid herbaceous sites, canopy greenness and photosynthesis were more tightly coupled, resulting in improved results with RS-driven models. Hybrid models capitalized on the combination of RS observations and meteorological information. LUE models were among the most accurate models to monitor GPP across all biomes, despite their simple architecture. Overall, we conclude that the combination of meteorological drivers and remote sensing observations is required to yield an accurate reproduction of the spatio-temporal variability of GPP. To further advance the performance of DGVMs, improvements in the soil moisture dynamics and vegetation evolution are needed.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":"39 21","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138597686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. We present previously unknown stacked bowl-shaped bioherms reaching a size of 45 cm in diameter and 40 cm in height from weakly solidified peloidal sand from the upper Sarmatian of the Paratethys Sea. The bioherms were mostly embedded in sediment, and the “growth stages” reflect a reaction on sediment accretion and sinking into the soft sediment. The bioherms are spirorbid–microclot–acicular cement boundstones with densely packed Janua tubes surrounded by microclots and acicular cement solidifying the bioherm. The surrounding sediment is a thrombolite made of peloids and polylobate particles (mesoclots) which are solidified synsedimentarily by micrite cement and dog-tooth cement in a later stage. The shape of the bioherms reflects a series of growth stages with an initial stage (“start-up stage”) followed by a more massive “keep-up stage” which grades into a structure with a collar-like outer rim and a central protrusion and finally by a termination of growth (“give-up stage”). The setting was a shallow subtidal environment with normal marine or elevated saline, probably oligotrophic, conditions with an elevated alkalinity. The stacked bowl-shaped microbialites are a unique feature that has so far been undescribed. Modern and Neogene microbialite occurrences are not direct analogues to the described structures, but the marine examples, like in The Bahamas, Shark Bay and the Persian Gulf, offer insight into their microbial composition and environmental parameters. The microbialites and the surrounding sediment document a predominance of microbial activity in the shallow marine environments of the Paratethys Sea during the late Middle Miocene, which was characterized by a warm, arid climate.
{"title":"Serpulid microbialitic bioherms from the upper Sarmatian (Middle Miocene) of the central Paratethys Sea (NW Hungary) – witnesses of a microbial sea","authors":"M. Harzhauser, O. Mandic, W. Piller","doi":"10.5194/bg-20-4775-2023","DOIUrl":"https://doi.org/10.5194/bg-20-4775-2023","url":null,"abstract":"Abstract. We present previously unknown stacked bowl-shaped bioherms reaching a size of 45 cm in diameter and 40 cm in height from weakly solidified peloidal sand from the upper Sarmatian of the Paratethys Sea. The bioherms were mostly embedded in sediment, and the “growth stages” reflect a reaction on sediment accretion and sinking into the soft sediment. The bioherms are spirorbid–microclot–acicular cement boundstones with densely packed Janua tubes surrounded by microclots and acicular cement solidifying the bioherm. The surrounding sediment is a thrombolite made of peloids and polylobate particles (mesoclots) which are solidified synsedimentarily by micrite cement and dog-tooth cement in a later stage. The shape of the bioherms reflects a series of growth stages with an initial stage (“start-up stage”) followed by a more massive “keep-up stage” which grades into a structure with a collar-like outer rim and a central protrusion and finally by a termination of growth (“give-up stage”). The setting was a shallow subtidal environment with normal marine or elevated saline, probably oligotrophic, conditions with an elevated alkalinity. The stacked bowl-shaped microbialites are a unique feature that has so far been undescribed. Modern and Neogene microbialite occurrences are not direct analogues to the described structures, but the marine examples, like in The Bahamas, Shark Bay and the Persian Gulf, offer insight into their microbial composition and environmental parameters. The microbialites and the surrounding sediment document a predominance of microbial activity in the shallow marine environments of the Paratethys Sea during the late Middle Miocene, which was characterized by a warm, arid climate.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":"3 10","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138603883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Zhao, Amin Dou, Zhiwei Zhang, Zhenyu Chen, Wenbo Sun, Yanli Feng, Xiaojuan Wang, Qiang Wang
Abstract. Reactive iron (Fe) oxides are vital for long-term soil or sediment organic carbon (SOC) storage. However, the patterns and drivers of Fe-associated organic carbon (Fe-OC) over global geographic scales under various ecosystem types remain controversial. Here, we provided a systematic assessment of the distribution patterns and determinants of Fe-OC content and its contribution to SOC (fFe-OC) by assembling a global dataset comprising 862 observations from 325 sites in distinct ecosystems. We found that Fe-OC content across global ecosystems ranged from 0 to 83.3 g kg−1 (fFe-OC ranged from 0 % to 82.4 %), reflecting the high variability of the Fe-OC pool. Fe-OC contents varied with ecosystem type being greater in wetlands with a high molar ratio of Fe-OC / dithionite-extractable Fe (Fed) compared with marine and terrestrial ecosystems. Furthermore, fFe-OC in wetlands was significantly lower than that in other ecosystems due to rich organic carbon (OC). In contrast with climate variables and soil pH, the random forest modeling and multivariate analysis showed that the Fe-OC : Fed and SOC were the predominant predictors of Fe-OC content and fFe-OC in wetlands and terrestrial ecosystems, whereas Fed content was a primary driver in marine ecosystems. Based on upper estimates of global SOC storage in various ecosystem types, we further estimated that 83.84 ± 3.8, 172.45 ± 8.74, and 24.48 ± 0.87 Pg of SOC were preserved by association with Fe oxides in wetland, terrestrial, and marine ecosystems, respectively. Taken together, our findings highlighted the importance of reactive Fe oxides in global SOC preservation, and their controlling factors were ecosystem specific.
摘要。活性铁(Fe)氧化物对土壤或沉积物有机碳(SOC)的长期储存至关重要。然而，不同生态系统类型下全球地理尺度上铁相关有机碳(Fe-OC)的分布格局和驱动因素仍存在争议。本文通过收集全球325个不同生态系统站点的862个观测数据，对Fe-OC含量的分布格局、决定因素及其对有机碳(Fe-OC)的贡献进行了系统评估。研究发现，全球生态系统的Fe-OC含量在0 ~ 83.3 g kg - 1之间(Fe-OC含量在0% ~ 82.4%之间)，反映了Fe-OC池的高变异性。Fe- oc含量随生态系统类型的不同而变化，与海洋和陆地生态系统相比，Fe- oc /二硫代盐可萃取铁(Fed)摩尔比高的湿地含量更高。此外，湿地由于富含有机碳(OC)， fe -OC显著低于其他生态系统。与气候变量和土壤pH值相比，随机森林模型和多变量分析表明，Fe-OC: Fed和SOC是湿地和陆地生态系统Fe-OC含量和Fe-OC含量的主要预测因子，而Fed含量是海洋生态系统Fe-OC含量的主要驱动因子。基于不同生态系统类型的全球有机碳储量上限，我们进一步估计湿地、陆地和海洋生态系统中与铁氧化物结合的有机碳储量分别为83.84±3.8、172.45±8.74和24.48±0.87 Pg。综上所述，我们的研究结果强调了活性铁氧化物在全球有机碳保存中的重要性，其控制因素是生态系统特有的。
{"title":"Ecosystem-specific patterns and drivers of global reactive iron mineral-associated organic carbon","authors":"B. Zhao, Amin Dou, Zhiwei Zhang, Zhenyu Chen, Wenbo Sun, Yanli Feng, Xiaojuan Wang, Qiang Wang","doi":"10.5194/bg-20-4761-2023","DOIUrl":"https://doi.org/10.5194/bg-20-4761-2023","url":null,"abstract":"Abstract. Reactive iron (Fe) oxides are vital for long-term soil or sediment organic carbon (SOC) storage. However, the patterns and drivers of Fe-associated organic carbon (Fe-OC) over global geographic scales under various ecosystem types remain controversial. Here, we provided a systematic assessment of the distribution patterns and determinants of Fe-OC content and its contribution to SOC (fFe-OC) by assembling a global dataset comprising 862 observations from 325 sites in distinct ecosystems. We found that Fe-OC content across global ecosystems ranged from 0 to 83.3 g kg−1 (fFe-OC ranged from 0 % to 82.4 %), reflecting the high variability of the Fe-OC pool. Fe-OC contents varied with ecosystem type being greater in wetlands with a high molar ratio of Fe-OC / dithionite-extractable Fe (Fed) compared with marine and terrestrial ecosystems. Furthermore, fFe-OC in wetlands was significantly lower than that in other ecosystems due to rich organic carbon (OC). In contrast with climate variables and soil pH, the random forest modeling and multivariate analysis showed that the Fe-OC : Fed and SOC were the predominant predictors of Fe-OC content and fFe-OC in wetlands and terrestrial ecosystems, whereas Fed content was a primary driver in marine ecosystems. Based on upper estimates of global SOC storage in various ecosystem types, we further estimated that 83.84 ± 3.8, 172.45 ± 8.74, and 24.48 ± 0.87 Pg of SOC were preserved by association with Fe oxides in wetland, terrestrial, and marine ecosystems, respectively. Taken together, our findings highlighted the importance of reactive Fe oxides in global SOC preservation, and their controlling factors were ecosystem specific.\u0000","PeriodicalId":8899,"journal":{"name":"Biogeosciences","volume":" 16","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138619718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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