Century-scale SOC deposition rates in terrestrial depositional environments under environmental change

… OC burial rates in 210 Pb-dated sediment cores from 116 … terrestrial C cycle, there has been little consideration of how … sediment focusing (the preferential deposition of fine-grained …

… This paper approaches the terrestrial sediment storage of … sedimentation rates from a relatively small number (<100) of impoundments, have calculated average sedimentation rates, …

… The first involves the loading to lakes of terrestrial organic C (… The sediment cores were sliced directly in field at each 0.5 … sedimentation rates and short-term C accumulation rates in the …

Lateral movements of soil organic C (SOC) influences Earth’s C budgets by transporting organic C across landscapes and by modifying soil-profile fluxes of CO2. We extended a previously presented model (Soil Organic C Erosion Replacement and Oxidation (SOrCERO)) and present SOrCERODe, a model with which we can project how erosion and subsequent deposition of eroded material can modify biosphere-atmosphere CO2 fluxes in watersheds. The model permits the user to quantify the degree to which eroding and depositional profiles experience a change in SOC oxidation and production as formerly deep horizons become increasingly shallow, and as depositional profiles are buried. To investigate the relative importance of erosion rate, evolving SOC depth distributions, and mineralization reactivity on modeled soil C fluxes, we examine two forests exhibiting distinct depth distributions of SOC content and reactivity, hydrologic regimes and land use. Model projections suggest that, at decadal to centennial timescales: 1) the quantity of SOC moving across a landscape depends on erosion rate and the degree to which SOC production and oxidation at the eroding profile are modified as deeper horizons become shallower, and determines the degree to which depositional profile SOC fluxes are modified; 2) erosional setting C sink strength increases with erosion rate, with some sink effects reaching more than 40% of original profile SOC content after 100 y of a relatively high erosion rate (i.e. 1 mm y-1); 3) even large amounts of deposited SOC may not promote a large depositional profile C sink in spite of large gains in autochthonous SOC post-deposition if oxidation of buried SOC is not limited; and 4) when modeled depositional settings receive a disproportionately large amount of SOC, simulations of strong C sink scenarios mimic observations of modest preservation of buried SOC and large SOC gains in surficial horizons, suggesting that C sink scenarios have merit in these forests. Our analyses illuminate the importance of cross-landscape linkages between upland and depositional environments for watershed-scale biosphere-atmosphere C fluxes, and emphasize the need for accurate representations and observations of time-varying depth distributions of SOC reactivity across evolving watersheds if we seek accurate projections of ecosystem C balances.

… fill of Lake Paringa was sampled with three 6 m sediment cores (Fig. 1). Deposits were … as a proxy for terrestrial sediment flux to the lake basin. Sedimentation rates were calculated by …

… deposition of fine-grained sediment. Proxy climate data from loess have the potential to improve our knowledge of Pleistocene climate change in terrestrial … based on sedimentation rate …

A sediment core (L2) from Larsemann Hills, Antarctica was analyzed for Biogenic Silica (BSi), Sand (%) and Total Organic Carbon (TOC). The 78 cm core length represents the time span of ~8.3 cal ka BP. The values of BSi from the core show prominent high productivity from ~8.3 to ~6 cal ka BP in comparison to less productivity in mid-late Holocene (~6 cal ka BP to recent). Moreover, high sand (%) infers the glacio-fluvial deposition from ~8.3 to ~5 cal ka BP TOC shows little variation through out the core, except in the upper ~10 cm (~4 cal ka BP) part wherein it is comparatively high. The increased TOC in the upper part of the core possibly indicates presence of algal mat due to exposure of the lake to the ice free (glacier free) conditions.

Abstract. Geogenic organic carbon (GOC) from sedimentary rocks is an overlooked fraction in soils that has not yet been quantified but influences the composition, age, and stability of total organic carbon (OC) in soils. In this context, GOC is the OC in bedrock deposited during sedimentation. The contribution of GOC to total soil OC may vary, depending on the type of bedrock. However, no studies have been carried out to investigate the contribution of GOC derived from different terrestrial sedimentary rocks to soil OC contents. In order to fill this knowledge gap, 10 m long sediment cores from three sites recovered from Pleistocene loess, Miocene sand, and Triassic Red Sandstone were analysed at 1 m depth intervals, and the amount of GOC was calculated based on 14C measurements. The 14C ages of bulk sedimentary OC revealed that OC is comprised of both biogenic and geogenic components. The biogenic component relates to OC that entered the sediments from plant sources since soil development started. Assuming an average age for this biogenic component ranging from 1000–4000 years BP (before present), we calculated average amounts of GOC in the sediments starting at 1.5 m depth, based on measured 14C ages. The median amount of GOC in the sediments was then taken, and its proportion of soil mass (g GOC per kg−1 fine soil) was calculated in the soil profile. All the sediments contained considerable amounts of GOC (median amounts of 0.10 g kg−1 in Miocene sand, 0.27 g kg−1 in Pleistocene loess, and 0.17 g kg−1 in Red Sandstone) compared with subsoil OC contents (between 0.53 and 15.21 g kg−1). Long-term incubation experiments revealed that the GOC appeared comparatively stable against biodegradation. Its possible contribution to subsoil OC stocks (0.3–1.5 m depth) ranged from 1 % to 26 % in soil developed in the Miocene sand, from 16 % to 21 % in the loess soil, and from 6 % to 36 % at the Red Sandstone site. Thus, GOC with no detectable 14C content influenced the 14C ages of subsoil OC and may partly explain the strong increase in 14C ages observed in many subsoils. This could be particularly important in young soils on terrestrial sediments with comparatively low amounts of OC, where GOC can make a large contribution to total OC stocks.

Perylene is a frequently abundant, and sometimes the only polycyclic aromatic hydrocarbon (PAH) in aquatic sediments, but its origin has been subject of a longstanding debate in geochemical research and pollutant forensics because its historical record differs markedly from typical anthropogenic PAHs. Here we investigate whether perylene serves as a source-specific molecular marker of fungal activity in forest soils. We use a well-characterized sedimentary record (1735-1999) from the anoxic-bottom waters of the Pettaquamscutt River basin, RI to examine mass accumulation rates and isotope records of perylene, and compare them with total organic carbon and the anthropogenic PAH fluoranthene. We support our arguments with radiocarbon (14C) data of higher plant leaf-wax n-alkanoic acids. Isotope-mass balance-calculations of perylene and n-alkanoic acids indicate that ∼40% of sedimentary organic matter is of terrestrial origin. Further, both terrestrial markers are pre-aged on millennial time-scales prior to burial in sediments and are insensitive to elevated 14C concentrations following nuclear weapons testing in the mid-20th Century. Instead, changes coincide with enhanced erosional flux during urban sprawl. These findings suggest that perylene is definitely a product of soil-derived fungi, and a powerful chemical tracer to study the spatial and temporal connectivity between terrestrial and aquatic environments.

Soil erosion and soil organic carbon (SOC) loss are not always linked linearly because SOC‐rich topsoil is eroded at the initial stages of degradation, while horizons with lower SOC content are eroded later, but often at higher rates. Small, silted‐up farm reservoirs potentially document this change during the period of sediment accumulation. This study tests the specific potential of small farm reservoir sediments from the South African Karoo to reconstruct 20th century SOC and total nitrogen (TN) change in rangeland soils. Five reservoir sediment profiles were sampled and texture, total organic carbon (TOC), TN and 137Cs of the samples were analyzed and compared. The results show that there clearly distinguishable flood couplets have been preserved in the sediment, illustrating their suitability for the chronological reconstruction of soil erosion and SOC. With one exception, the older sediments contain more TOC and TN than the younger ones. The TOC changed mostly in earlier than later stages of deposition, which is indicative of soil degradation early after the construction of the dams in the 1920s and 1930s. These distinct changes illustrate that the small reservoir sediments have the potential to reconstruct the impact of land‐use and associated soil erosion on SOC change in rangelands. Their analysis can therefore contribute to a better understanding of the land‐use associated changes of the global carbon cycle during the 20th century.

… sedimentation rate in Lone Pine Lake for the past century … The focus-corrected sediment SOC concentrations and fluxes … Lake catchment size does not explain the SOC sediment flux …

… deposition records of decadal to century scale (c. 0.5 cm a … Concentrations of suspended sediment in the river are minimal. … This study has identified variations in deposition rate for a …

… to be at the scale of the fluvial sediment load delivered to the … variation in the sediment load of rivers: across centuries fora few … Rivers that carry the requisite sediment concentration for …

The (137)Cs and (210)Pb dating of a 61-cm long sediment core retrieved from a drinking water reservoir (Lake Brêt) located in Switzerland revealed a linear and relatively high sedimentation rate (~1 cm year(-1)) over the last decades. The continuous centimeter scale measurement of physical (porewater and granulometry), organic (C(org), P, N, HI and OI indexes) and mineral (C(min) and lithogenic trace elements) parameters therefore enables reconstructing the environmental history of the lake and anthropogenic pollutant input (trace metals, DDT and PCBs) at high resolution. A major change in the physical properties of the lowermost sediments occurred following the artificial rise of the dam in 1922. After ca. 1940, there was a long-term up-core increase in organic matter deposition attributed to enhance primary production and anoxic bottom water conditions due to excessive nutrient input from a watershed predominantly used for agriculture that also received domestic effluents of two wastewater-treatment plants. This pattern contrasts with the terrigenous element input (Eu, Sc, Mg, Ti, Al, and Fe) which doubled after the rising of the dam but continuously decreased during the last 60 years. By comparison, the trace metals (Cu, Pb and Hg) presented a slight enrichment factor (EF) only during the second part of the 20th century. Although maximum EF Pb (>2) occurred synchronously with the use of leaded gasoline in Switzerland (between ca. 1947 and 1985) the Hg and Cu profiles exhibited a relatively similar trend than Pb during the 20th century, therefore excluding the alkyl-lead added to petrol as the dominant (atmospheric) source of lead input to Lake Brêt. Conversely, the Cu profile that did not follow the decrease registered in Pb and Hg during the last 10 years, suggests an additional source of Cu probably linked to the impact of agricultural activities in the area. In absence of heavy industries in the catchment, the atmospheric deposition of DDT and PCBs via surface runoff followed the historical emissions of POPs in Switzerland. Such result highlights the regional contamination of freshwater resources by the large-scale emission of toxic industrial chemicals in the 1960s and 1970s as well as the efficiency of the regulatory measures subsequently taken.

… organic matter have been used successfully in the past to reconstruct shifts in water column productivity and anthropogenic organic matter inputs to lake … sedimentary deposit at stations …

… Lake with the history of human activities, to examine the influence of the natural environment and human activities on the humification of organic carbon… environment in the lake over the …

… and stimulates the transport-deposition process of organic carbon-rich soil particles, which … erosion and carbon export due to ecological protection and reservoir management when …

The patterns of organic carbon sequestration in lakes, along with their temporal dynamics, have profound implications for assessing the strength of terrestrial carbon sinks and the global carbon budget. The complexity of fluctuations in organic carbon burial in freshwater lake basins, along with the intricate interactions among various controlling factors over time, remains challenging to comprehend. By utilizing data on the organic carbon burial of sedimentary cores from twelve plateau lakes in a gradient of urbanization, this study employed a rigorous methodology to quantify the factors and origins that contribute to lacustrine carbon sequestration. The findings indicate that the rate of Total Organic Carbon (TOC) accumulation in lakes in highly urbanized areas has significantly surpassed that in areas with minimal urbanization since 1985. This trend of divergence has persisted for more than four decades. During the period from 1958 to 2008, soil nutrient characteristics (29.576 %) and human impact (16.684 %) were the major factors regulating the organic carbon burial in plateau lakes. Human pressures indirectly impact carbon sequestration through earth-surface processes in the lake basin, causing carbon burial to lag behind environmental indicators (e.g., δ13C and C/N) by approximately 5 years. Meanwhile, the carbon sequestration efficiency of plateau lakes shows a positive feedback to climatic warming with intensified urbanization, primarily regulated through the impacts on lake basin environments. The results will further enhance our understanding of the response of the lake ecosystem carbon cycle to anthropogenic influences.

Abstract. Even though human-induced eutrophication has severely impacted temperate lake ecosystems over the last centuries, the effects on total organic carbon (TOC) burial and mineralization are not well understood. We study these effects based on sedimentary records from the last 180 years in five Swiss lakes that differ in trophic state. We compare changes in TOC content and modeled TOC accumulation rates through time to historical data on algae blooms, water column anoxia, wastewater treatment, artificial lake ventilation, and water column phosphorus (P) concentrations. We furthermore investigate the effects of eutrophication on rates of microbial TOC mineralization and vertical distributions of microbial respiration reactions in sediments. Our results indicate that the history of eutrophication is well recorded in the sedimentary record. Overall, eutrophic lakes have higher TOC burial and accumulation rates, and subsurface peaks in TOC coincide with past periods of elevated P concentrations in lake water. Sediments of eutrophic lakes, moreover, have higher rates of total respiration and higher contributions of methanogenesis to total respiration. However, we found strong overlaps in the distributions of respiration reactions involving different electron acceptors in all lakes regardless of lake trophic state. Moreover, even though water column P concentrations have been reduced by ∼ 50 %–90 % since the period of peak eutrophication in the 1970s, TOC burial and accumulation rates have only decreased significantly, by ∼ 20 % and 25 %, in two of the five lakes. Hereby there is no clear relationship between the magnitude of the P concentration decrease and the change in TOC burial and accumulation rate. Instead, data from one eutrophic lake suggest that artificial ventilation, which has been used to prevent water column anoxia in this lake for 35 years, may help sustain high rates of TOC burial and accumulation in sediments despite water column P concentrations being strongly reduced. Our study provides novel insights into the influence of human activities in lakes and lake watersheds on lake sediments as carbon sinks and habitats for diverse microbial respiration processes.

Artificial lakes (reservoirs) accumulate sediment and organic carbon (OC) over time. We investigated sedimentation processes in a dryland reservoir and informed OC burial and potential preservation. Our study site, Elephant Butte Reservoir on the Rio Grande, New Mexico, USA receives inflows from sediment‐laden, monsoon‐driven flash floods. Using field data, historical reservoir sedimentation survey and river flux (water, sediment, and OC) data, we estimated sedimentation and carbon burial volumes and rates within the delta, reservoir bottom, and whole reservoir during wet (1980–1988) and dry (2007–2017/2019) climate periods. During severe drought (2021–2022), we measured suspended sediment and OC concentrations for characteristic (seasonal) phases of the river hydrograph, monitored delta sedimentation patterns, and observed river outflow plume dynamics. Measured suspended sediment concentrations (mean = 8,818 mg/l, median = 1,769 mg/l) frequently surpassed the hyperpycnal plume threshold (1,000 mg/l), especially during flash floods (maximum = 46,718 mg/l). River total OC content averaged 5.2% ± 12.2%, increasing to 6.3% ± 10.3% in the summer. Whole reservoir linear sedimentation averaged 3.1 ± 1.4% (dry)–4.0 ± 4.2% (wet) cm/yr, with higher rates on the reservoir bottom (5.0 ± 0.3% cm/yr) than the delta (0.8 ± 1.1% cm/yr) during drought from hyperpycnal plume deposition, potentially preserving OC. Comparisons of OC content in suspension and deposited OC in the delta indicate partial OC preservation. Estimated whole reservoir OC burial is higher during dry than wet conditions (391 ± 43.6% vs. 82.4 ± 56.4% g C/m2yr), suggesting that dryland reservoirs may be efficient carbon sinks during these periods.

… Soil erosion or deposition rates (based on 137 Cs inventories) ranged from 34.8 (erosion) to … this study showed that soil redistribution can result in burial of eroded OC-rich surface soil in …

Abstract. Is anthropogenic soil erosion a sink or source of atmospheric carbon? The answer depends on factors beyond hillslope erosion alone because the probable fate of mobilized soil carbon evolves as it traverses the fluvial system. The transit path, residence times, and the resulting mechanisms of C-loss or gain change significantly down-basin and are currently difficult to predict as soils erode and floodplains evolve – this should be a key focus of future research.

Rewetting drained wetlands restores long-term carbon storage by reviving organic carbon burial in sediments and rebuilding carbon stocks, but the decades-long recovery pathway is uncertain. Sediment cores were dated using naturally occurring radioactive lead-210, verified with cesium-137 from past nuclear testing, to reconstruct organic carbon burial rates before drainage and for 4–40 years after rewetting across two restoration chronosequences in dry and wet climate zones; undisturbed wetlands provided benchmarks. Burial rates in undisturbed wetlands (median: 0.60 Mg C ha-1 yr-1) were comparable to pre-drainage rates in rewetted wetlands (median: 0.53), suggesting pre-drainage conditions can guide site-specific recovery targets. After ditch plugging, burial rates increased rapidly (net change: 0.28–1.01 Mg C ha-1 yr-1 within 14 years) but then declined and converged on the baseline by about 40 years. Meanwhile, total organic carbon stored in sediments rose steadily, reaching 24.6 Mg C ha-1 after four decades. Organic carbon sequestration rates in rewetted wetlands increase during early restoration and then stabilize within ~40 years, while organic carbon stocks accumulate steadily, according to radiometric dating and organic matter quantification in Canadian wetlands

… reconstruct the environment in the past, especially the global … cycling of carbon of each carbon pool from “cradle” to “grave”… while the soil carbon loss due to land use change is between …

… by reconstructed climate, land use, and CO 2 concentrations. Although land use change was the major control on the carbon … soil carbon storage and a positive net flux of carbon into the …

… soils and associated SOC and TSN were redistributed at the landscape scale, land use change and … to behave as soil C and N sinks within the soil erosion subsystem since the 1999s. …

… Land-use change The lithology of the sediment core in combination with pollen analysis allows the reconstruction of the landscape development around Frickenhauser See during the …

Abstract. Humans have substantially altered soil and landscape patterns and properties due to agricultural use, with severe impacts on biodiversity, carbon sequestration and food security. These impacts are difficult to quantify, because we lack data on long-term changes in soils in natural and agricultural settings and available simulation methods are not suitable to reliably predict future development of soils under projected changes in climate and land management. To help overcome these challenges, we developed the HydroLorica soil-landscape evolution model, that simulates soil development by explicitly modelling the spatial water balance as driver of soil and landscape forming processes. We simulated 14500 years of soil – formation under natural conditions for three scenarios of different rainfall inputs. For each scenario we added a 500-year period of intensive agricultural land use, where we introduced tillage erosion and changed vegetation type. Our results show substantial differences between natural soil patterns under different rainfall input. With higher rainfall, soil patterns become more heterogeneous due to increased tree throw and water erosion. Agricultural patterns differ substantially from the natural patterns, with higher variation of soil properties over larger distances and larger correlations with terrain position. In the natural system, rainfall is the dominant factor influencing soil variation, while for agricultural soil patterns landform explains most of the variation simulated. The cultivation of soils thus changed the dominant factors and processes influencing soil formation, and thereby also increased predictability of soil patterns. Our study highlights the potential of soil-landscape evolution modelling for simulating past and future developments of soil and landscape patterns. Our results confirm that humans have become the dominant soil forming factor in agricultural landscapes.

… , historical ecosystem transformations, and long-term variations in carbon storage dynamics (… tools for resolving complex organic carbon dynamics in lacustrine systems, overcoming the …

… representing about 5000 yrs of history. It combines a palynological approach with a geochemical and petrographic study of sedimentary organic matter. The palynological data allows to …

… oxidation and to biological utilization, it is an especially dynamic component of sediments. … can record the depositional history of organic matter sources in lake sediments. n-Alkane …

… sediment to serve as a sensitive recorder of terrestrial ecosystem variability. This study focuses on a lacustrine … We present a model of carbon dynamics of a lacustrine system (Fig. 5) …

… Lakes are dynamic response systems that integrate … The lacustrine sedimentology of Gaoyou Lake has been little … (MS), total organic carbon (TOC) and C/N results from sediment cores …

… record, rich in information about paleoenvironments and changing dynamic structures, … nous organic matter can be separated quantitatively from truly lacustrine organic sediments, the …

Stable organic carbon (OC) burial into lacustrine sediments was the important C fixation path for atmospheric C reduction. However, OC retention effect and stability mechanisms in sediments was still unclear at the molecular scale during the burial period. Chronology and OC fractions were measured for the sediments from two freshwater lakes. Three-dimensional fluorescence and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) were used to detect the change in the forms and molecular structure of soluble OC (SOC). Remarkably increasing TOC and total nitrogen (TN) concentrations along with the decreasing TOC/TN (C/N) values upwards occurred in the sediment columns indicated the weakened terrigenous OC and N inputs from about the 1980s. The OC mineralization contributed to the decrease of C burial in deeper sedimentary layers. However, higher SOC concentrations was found in deeper depths, suggesting that SOC facilitated the OC accumulation and fixation in the sediments and triggered the higher OCBR values over time. Additionally, obvious fluorescence intensity existence throughout the the whole sediment cores suggested the synchronous accumulation of both humic acid-like and fulvic acid-like materials over time as dominant SOC fractions. Higher fluorescence intensity at upper sediment layers indicated the SOC burial as humic acid-like materials with stronger sequestration potential. The persistence of fluorescence signal suggested that fulvic acid-like materials dominated the SOC immobilization and resistance to mineralization in the sediments. Finally, FT-ICR-MS analysis showed that remarkable accumulation of lipids with abundances from 31 to 44 % of organics was attributed to the decomposition of lignins and dominated CHO and CHON formulas and OC compounds. Lipids and lignins with higher abundances dominated the SOC burial and fixation over time even though mineralization occurred. Our work testified that lipids and lignins contributed to the majority of humic acid-like materials and subsequent OC retention in the lacustrine sediments at the geological time scale.

Varved lake sediments provide an invaluable archive of natural and human-induced environmental changes. We present results of sedimentological, geochemical and pollen analyses …

… climate and environmental history of Central Finland. … the amount of organic matter that accumulates in sediments. … catchment dynamics and the accumulating lacustrine sediments. …

… During periods of higher precipitation (“wetter” or “moister” conditions), we expect organic matter in the sediments to increase as productivity in the water column is enhanced by the …

Wigry Lake represents one of the most beautiful and valuable postglacial lakes that is located in the north-eastern part of Poland. It has been an object of scientific interest for over a century, but the most intense period of research started in 1997 and resulted in the production of numerous papers of a multidisciplinary range. The lake is especially well analyzed in terms of its sediments, which were studied using geophysical methods and using traditional lake cartography based on the sampling of sediments and their geochemical characterization. Nearly two decades of research has resulted in the extraction of over 1200 sediment samples, which facilitated the analysis and the description of five main sediment types that can be found at the bottom of Wigry Lake, i.e., carbonate gyttja, lacustrine chalk, clastic sediment, fluvial-lacustrine sediment, and organic gyttja. A very thorough vertical as well as spatial examination of Wigry Lake sediments, together with paleobiological research and isotopic dating, allowed researchers to analyze the history of environmental changes in the lake and its immediate vicinity, including anthropogenic changes. Wigry Lake had been preserved as a pristine lake for a long time, and, despite the significant growth of anthropopressure, which began in the 17th century and intensified in the 20th century, it retained its natural character to a large extent. This was possible mainly due to the favorable morphometry of the lake (large depth and capacity of the reservoir) and different forms of active and passive protection, introduced mainly after the establishment of the Wigry National Park in 1989.

… The larger nutrient enrichment observed at site OHT is most likely due to a preferential sedimentary dynamics, since site OH2 is more influenced by tides than OHT, which is currently …

Wetlands serve as vital carbon sinks; however, compared with the surface carbon pool, the relative stock and stability of organic carbon (OC) buried in deep sediment layers remain uncertain, particularly in alpine regions. Based on 42 sediment across seven wetlands on the Qinghai-Xizang Plateau, this study disentangled the OC accumulation process and its drivers since the Holocene. Our results highlighted that deep sediments ( >1 m) stored ~70% of the total OC in alpine wetlands, much of which was labile. Historical warming facilitated the accumulation of such labile OC. Moreover, an intercalated sedimentary structure, formed by silt and fine-grained clay both below and above the OC-rich layer, prevented them from rapid decomposition. Given that elevated groundwater temperatures and intensified hydrological processes in alpine regions may stimulate the decomposition of these massive labile OC pools, releasing carbon into surface water or the atmosphere, future climate change assessments should take this long-overlooked carbon pool into account. Deep sediments ( < 1 meter) in alpine wetlands on the Qinghai-Xizang Plateau store about 70% of total organic carbon, much of it labile; past warming and clay–silt–clay layering enhanced deep carbon burial, as shown for wetlands in this region.

Multi-centennial C budgets in forested watersheds require information on forest growth, detritus turnover, and disturbances, as well as the transfer to and fate of terrestrial C in aquatics systems. Here, a sediment gravity core was collected from a drinking water reservoir in Canada, and analyzed for temporal changes in charcoal, magnetic susceptibility, carbon, and nitrogen. These indicators were used to assess disturbance history and terrestrial C sequestration in sediments. During the reservoir development period from 1910 to 2012, charcoal flux and magnetic susceptibility increased ca. 10 years after nearby fire and forest-clearing events associated with reservoir expansion. Total C and δ13C gradually declined during the development period, likely due to increased inputs of mineral soil from human activity. Concurrently, total terrestrial C sequestered in sediments, estimated using three or eight marker compounds, ranged between 3557 and 5145 Mg C/100 yrs, accounting for 11%–17% of DOC exports to the reservoir (30,640 Mg C/100 yrs), as estimated from a previously developed terrestrial carbon budget model. In comparison, mixed-severity fires burned around the reservoir during the pre-development period (pre-1910), as evidenced by stand ages and/or increases in charcoal flux. In general, decreased terrestrial C flux was associated with higher-severity fires that burned between 1870 and 1890 and perhaps around 1790. Further, comparisons show that soil erosion was up to 3× greater in the development versus the pre-development period. Overall, this investigation revealed the impact of land use change and fire on watershed carbon budgets and advanced a previously developed pyGC-MS methodology that demonstrated the amount of terrestrial and aquatic C being buried in sediment. It also identified the fraction of terrestrial C that was exported from the forest to the reservoir and sequestered in the sediment, uncommon data that could inform current and future landscape C budget modelling studies in this region.

… Intertwined effects of climate and land use change on environmental dynamics and carbon accumulation in a mangrove-fringed coastal lagoon in Java, Indonesia. Global Change …

… on land can bury vast quantities of organic carbon, roughly … agriculture, water supplies, land reclamation, navigation, and … Much of the sediment derived from rapidly eroded uplands …

… sedimentary carbon during soil development and land-… carbon input with roots and dissolved organic matter and progressing mineralization of the old, sediment-derived organic carbon. …

… (MARs) of sediment derived from 210 Pb and 137 Cs along with total organic carbon content (TOC… of land reclamation, consequently resulting in the decrease in the potential capacity of …

Pre-industrial human impacts on the past environment are apparent in different proxy records at different times in different places. Recognizing environmentally transformative human impacts in palaeoenvironmental archives, as opposed to natural variability, is a key challenge in understanding the nature of the transition to the Earth’s current ‘Anthropocene’ condition. Here, we consider the palaeoenvironmental record for Iceland over the past 2.5 ka, both before and after the late ninth century human settlement (landnám). The Scandinavian colonization of the island was essentially abrupt, involving thousands of people over a short period. The colonization triggered extensive changes in Icelandic ecosystems and landscapes. A volcanic ash known as the Landnám tephra was deposited over most of Iceland immediately before the settlement began. The Landnám tephra layer thus provides a uniquely precise litho-chrono-stratigraphic marker of colonization. We utilize this marker horizon as an independent definition of the effective onset of the local palaeoanthropocene (which is conceptually related to, but distinct from, the global Anthropocene). This allows us to evaluate proxy records for human impact on the Icelandic environment and to assess how and when they show transformative impact. Based on this analysis, we consider the implications for understanding and defining the Anthropocene in those areas of the Earth where such a clear independent marker of the onset of significant human impacts is lacking.

… ment cores allows reconstructing the chronological record … distances from the Holocene centroid to Anthropocene living … HST) molluscan assemblages (deposited prior to the twentieth …

… Since catchment size can be assumed to have remained constant during the Holocene it follows that changes in floodplain deposition must reflect the sum of the input of sediment to …

The AWG (Anthropocene Working Group) proposed 1952 CE as the onset of the Anthropocene, marked by the detonation of the first hydrogen bomb, and designates Crawford Lake’s sediments in Canada as the potential stratotype. While the proposal for the Anthropocene as an epoch has been rejected by the SQS (Subcommision on Quaternary Stratigraphy), ongoing discussions regarding this debate remain unresolved. Here, we explore the possible biases and pitfalls of selecting the onset date from a singular site as the GSSP (Global boundary Stratotype Section and Point) for a chronostratigraphic boundary, using the potential Holocene-Anthropocene boundary as an example. We address the challenges of identifying changes in anthropogenic markers, along with the inherent measurement and age uncertainties, by employing a multilevel Bayesian change point analysis integrated with an errors-in-variables approach applied to proxy data. Our analysis utilizes plutonium isotopes ((239+240)Pu), SCPs (spheroidal carbonaceous fly-ash particles), and radiocarbon (F14C) records from multiple locations established to evidence global anthropogenic imprints. Key findings include the identification of a population-level change point for (239+240)Pu at 1953 CE (1951.5–1954.5). While the standard practice for defining the onset date of a stratigraphic boundary typically involves selecting the date from the stratotype, our results suggest that 1953 CE should be the preferred date to define the onset of a potential Anthropocene Epoch. However, 1952 CE, which coincides with the first H-bomb test, cannot be statistically rejected as an alternative. Geographical clustering of SCPs data highlights regional variations in proxy signatures, while F14C results emphasize a lag of 5.5–9 years corresponding to carbon residence time. Our research contributes to discussions surrounding the delineation of a potential boundary between the Holocene and Anthropocene Epochs. Additionally, it provides methodological insights into identifying change points in multiple datasets and temporal lags in the environmental impacts of human activities.