Estimates Of Sedimentation Rates Research Articles

Effect of Vitamin D deficiency and some hematological parameters in Iraqi female patients with Systemic Lupus Erythematosus

Background: Systemic Lupus Erythematosus (SLE) is a chronic inflammatory autoimmune disease that affects multiple organs. Vitamin D deficiency is considered potential environmental factor triggering some autoimmune disorders, including SLE. This study was performed for determination of effect of vitamin D deficiency in SLE infection or disease worsening, and the relationship of ESR, HB, and WBCs with level of vitamin D in SLE disease, in addition to determine which of the previous parameter may describe the disease case of patients. Methods: This study included fifty three (53) SLE female patients and twenty six (26) healthy females were included. White blood count (WBC) and Heamoglobin (Hb) were determined in complete blood count (CBC) device, traditional Westergren method was used for Erythrocyte sedimentation rate (ESR) estimation, vitamin D was measured by using enzyme link immune-sorbent assay (ELISA) Kit. Results: The results showed a significant decrease in the hemoglobin levels in the SLE patients; significant increase was noticed in the ESR of SLE patients and significant increase was noticed in the WBC counts compared to the control group’s samples. A significant decrease in serum levels of vitamin D in patients compared to apparently healthy controls. Conclusions: Photosensitivity to sun in SLE patients contributed in decrease of vitamin D blood-levels. According to the ROC results, each of Hb, WBC, ESR and vitamin D may describe the disease case of patients.

Continuous deposition of pre-aged organic carbon in the southern Mariana Trench since the last deglaciation

One of the key challenges in understanding the role of hadal trenches in the marine organic carbon (OC) cycle is the need to distinguish OC sources, assess accumulation rates, and identify controlling processes. To address this, sediment core samples from the southern Mariana Trench were analyzed for their contents and carbon isotopes (13C and 14C) of both total OC (TOC) and saturated long-chain fatty acid (n-LCFA). Our findings indicate that sedimentary OC in the southern Mariana Trench is primarily derived from marine sources, as indicated by TOC-δ13C values ranging from −19.9‰ to −17.0‰ and the ratios of TOC to total nitrogen (TOC/TN) of 5.5–8.4. The 14C ages of TOC and n-LCFA ranged from 7159 to 22,662 yr and 8713 to 22,819 yr, respectively, with both showing gradual down-core increasing trends. This allows for a conservative estimation of sedimentation rate of 17.5–18.7 cm kyr−1 in the southern Mariana Trench, leading to a sedimentary OC accumulation rate of 529–942 g C m−2 kyr−1, which is 1–2 orders of magnitude higher than that observed in the abyssal plain. We propose that the continuous lateral downslope transport played a significant role in focusing pre-aged OC into the southern Mariana Trench. Therefore, hadal trenches are likely to accumulate substantial amounts of sedimentary OC in the deep ocean.

Drivers of organic carbon distribution and accumulation in the northern Barents Sea

Sedimentary properties and accumulation rates on the continental shelf and in the deep sea reflect temporal oceanographic, biological and chemical processes occurring in the water column and the sediment surface. We used the radionuclides 210Pb, 226Ra, and 137Cs activities to estimate sedimentation rates during the last century at nine stations in the northern Barents Sea region. Elemental (C, N) and stable isotopic composition (δ13C, δ15N) were also analysed from the nine stations sampled in August 2018, and, for five other stations sampled in August and December 2019, and in March and May 2021. Sediment accumulation rates varied between 130 and 1 410 g m−2 y−1. The < 63 μm normalized total organic carbon (TOC63) and the total nitrogen from the sediment surface varied between 0.90–2.56 % and 0.13–0.33 %, respectively. Ice-free shelf stations had higher TOC63 and possibly fresher organic matter (high δ13C, low δ15N) than ice-covered more northern stations. The opposite trend was observed for total inorganic carbon. We found that these trends in biogeochemical parameters were spatially structured by the winter sea ice concentration and biological production differences, and exhibited a south-north separation of the Polar Front region. The low and stable organic carbon accumulation rate (1.7–13.4 g Corg m-2 y−1; ARtoc) is a function of slow sedimentation rates, and high degradation and residence time in the water column and at the sediment–water interface. Overall, the ARtoc has been stable for the past 100 years, with a slight increase from the early 1970s to the present at the shelf and slope stations. Our results highlight that spatial scales of variability of the studied sedimentary parameters are linked to spatial patterns of important environmental variables (e.g., chlorophyll-a, sea ice concentration) in the region. In contrast, no seasonal differences were observed in the sediment parameters of revisited stations, and the dated sediment geochemical profiles did not exhibit substantial longer-term variation. This means that climate-induced changes in variables that modify the sedimentary geochemistry of the environment may affect benthic community activity and structure before leaving a record in ARtoc.

Biostratigraphy and sedimentation rate estimation of Quaternary sediments of the Krishna-Godavari Basin, Bay of Bengal: Evidence from NGHP-01 Holes 10D, 5C and 3B

The deposition of a substantial amount of clastic sediments in the Krishna Godavari Basin formed a thick layer of nannofossil-rich clay known as the Godavari Clay Formation. This clayey sequence is a treasure trove for unveiling paleoclimatic and paleoceanographic information. Numerous radiometric dates from the topmost portion of this clay (top 27m) are available, covering the last 43 ka. However, the availability of data on age connotation with considerably high resolution for the deeper sediments is rare and is still awaited. In this study, we pursued nannoplankton and planktic foraminiferal investigations on the top 198 m (Hole 10D), 300 m (Hole 3B), and 198 m (Hole 5C) sediments of this basin to generate multiple age data with a relatively high resolution. First Occurrence (FO) and Last Occurrence (LO) of nannoplankton taxa Emiliania huxleyi, Helicosphaera inversa, Helicosphaera sellii, large Gephyrocapsa spp., Pseudoemiliania lacunosa, Reticulofenestra asanoi, and planktic foraminiferal taxa Globorotalia flexuosa and Globigerinella calida are considered as potential index taxa for establishing the bioevents as well as biostratigraphy.Based on these, we have identified nine events from Hole 10D, six events from Hole 3B, and seven events from Hole 5C, which are potential for assigning the relative ages.We also observed two-fold variations in sedimentation rates in all the holes and one hiatus at 110.73 mbsf in Hole 5C, indicating a shift in climate and basinal settings. A high sedimentation rate of greater than 20.59 cm/ka after approximately 0.4 Ma at all the holes is probably linked to the intensification of the Indian summer monsoon across the mid-Brunhes Epoch. The significantly low sedimentation rates (less than 14.62 cm/ka) in older sediment sequences before 0.4Ma is probably related to the relatively weak monsoonal activity. The generated age data, variations in sedimentation rates, and identified hiatus are considered to be potential for delineating paleoclimatic and paleoceanographic changes of this area since the Calabrian Stage.

Event-based soil erosion and sediment yield modelling for calculating long-term reservoir sedimentation in the Alps

ABSTRACT Among the most characteristic offsite effects of soil erosion, reservoir sedimentation is one of the longlasting problems pertaining to storage capacity and dam operations. In this work, sedimentation rates of the Fortezza reservoir in South Tyrol (Italian Alps) are analysed for nine erosive events over 14 months. Sediment rates are calculated through a modified Universal Soil Loss Equation (USLE) combined with a Sediment Delivery Ratio (SDR) module at 2.5 m resolution. The topographic factor is adjusted to the Alpine terrain, and an additional factor is included to consider the nonerodible parts of the basin. The results are validated against a 14-month sediment yield obtained by high-resolution (0.2 m) reservoir bathymetric analyses. The calculated sediment yield has an absolute deviation of 4.8% from the measured one. The results indicate that these methods can be successfully applied for the estimation of reservoir sedimentation rates in the Alps.

Impact of climate change and anthropogenic activities on lacustrine ecosystems of the Kashmir Valley, NW Himalaya, India

AbstractDue to the significant sedimentation and anthropogenic pressures, the Kashmir Himalaya lakes (Dal, Wular, Manasbal) located within and in the vicinity of urban settlements are experiencing massive degradation. The unique climate, geographic setting, and rock degradation owing to the tectonic uplift of the area, contribute to increased sedimentation in these lakes. The sewage and other anthropogenic pressures have also increased various minerals including nitrogen influx in these lakes. Total organic carbon levels in the Dal Lake are high and range from 2.72% to 25.12%, with nitrogen levels ranging from 0.92% to 9.81%. The total organic carbon of Wular and Manasbal Lakes ranges from 0.83% to 4.52%, and 3.11% to 13.74% with nitrogen ranging from 0.06% to 0.5% and 0.20% to 1.96%, respectively. The estimated sedimentation rates for the Wular, Manasbal, and Dal Lakes are 0.125 cm/yr, 0.44 cm/yr, and 0.93 cm/yr. Given these factors and the geographic setting of Kashmir Himalaya, it is believed that under the sustained threat of climate change and anthropogenic pressure, mitigation strategies to control sedimentation and pollution are unavoidable for the long‐term survival of these valuable ecosystems. This review examines contributing factors, explores potential consequences, and proposes mitigation measures, to save these important aquatic ecosystems from further deterioration.

Re‐investigation of the Bispingen palaeolake sediment succession (northern Germany) reveals that the Last Interglacial (Eemian) in northern‐central Europe lasted at least ~15 000 years

Investigating past interglacial climatic and environmental changes can enhance our understanding of the natural rates and ranges of climate variability under interglacial boundary conditions. However, comparing past interglacial palaeoclimate records from different regions and archives is often complicated by differing and uncertain chronologies. For instance, the duration of the Last Interglacial in Europe is still controversial as southern European palaeoclimate records suggest a duration of ~16 500–18 000 years, while a length of only ~11 000 years in northern‐central Europe was previously inferred from the analysis of partly annually laminated (varved) palaeolake sediments recovered at Bispingen, northern Germany. To resolve this discrepancy, we here present sediment microfacies, geochemistry and pollen data from a new sediment core from the Bispingen palaeolake sediment succession, covering the entire Last Interglacial (Eemian) and the earliest part of the Last Glacial (Weichselian). In particular, we provide evidence that the duration of the Last Interglacial at Bispingen must have been hitherto underestimated due to the investigation of an incomplete sediment core. Using microscopic varve counting and sedimentation rate estimates for non‐varved sections on the new sediment core, we show that the Eemian in northern‐central Europe probably lasted at least ~15 000 years, about 4000 years longer than previously thought. This new duration estimate is in much better agreement with results from southern European palaeoclimate records, clarifying the enigma of a steep trans‐European vegetation gradient for several millennia at the end of the Last Interglacial.

Magmatism at an ultra-slow spreading rift: high-resolution geomorphological studies of a Red Sea Rift segment in Hadarba Deep

The mid-ocean rift in the Red Sea is one of the youngest rifting systems on Earth. Only recently, state-of-the-art methods and modern deep-sea instruments have been used to explore this young and unique volcanic system. During the first autonomous underwater vehicle surveys of the Red Sea Rift in Spring 2022, we collected multibeam bathymetry, backscatter, sub-bottom profiler data, and water column data over a 9 km long ridge segment in the Hadarba Deep between 22.49°N and 22.56°N to investigate the volcano-tectonic processes of this ultra-slow spreading segment (12 mm/year spreading rate). The high-resolution hydroacoustic data was used to (1) delineate and quantify the geometry of tectonic structures and individual lava flows, (2) define lava flow morphology and eruption style, (3) estimate relative ages of flows and features, and (4) retrace the evolution of the volcanic activity. In addition, the geochemistry of several young lava flows provides information on the relation between the different magma that supply these eruptions. About 90 eruptive units with variable sedimentary cover have been identified within the 43 km2mapped region. The oldest lava flows are buried under 3 to 4.2 m of sediment, indicating ages of up to ~30 ka based on average sedimentation rate estimates (~14 cm/ka), while the youngest eruptions are covered by&amp;lt;10 cm of sediment, and are thus younger than 700 years. Three volcanic phases have been identified based on changes in flow morphology and distribution, and tectonic pattern. All three axial phases have an average eruptive frequency of ~100-250 years. The segment displays an overall low tectonic extension (&amp;lt;10% of the total extension) and low vertical offset. Our geomorphological maps, analyses, and statistics reveal a moderately faulted, ultra-slow spreading MOR segment in the Red Sea with a surprisingly large amount of magmatic extension, implying that the segment has been underlined by a large magma supply for at least 15 ka. All these observations provide valuable implications for the formation history of the Red Sea Rift and the formation of ultra-slow spreading crust.

Patterns and cyclicity of Quaternary sedimentation above a subducting seamount at Rock Garden (Central Hikurangi margin, New Zealand)

Rock Garden (RG), located east off the North Island of New Zealand, is part of an accretionary ridge that is influenced by seamount subduction. Two ∼37 m long sediment cores, drilled with the seafloor drill rig (MeBo200) from RG, provide a continuous sedimentary record of the period between 1.95 and 0.4 Ma. This period, the Early-Middle Pleistocene transition (EMPT), was marked by a progressive increase in the amplitude of climate oscillations, and a shift of Milanković cycles from 41 ka towards a quasi-100 ka frequency in the absence of any significant change in orbital forcing. From the recovered core material of cores GeoB 20824–4 and GeoB 20846–1, we determined sediment physical properties, oxygen isotope (δ18O) values, and element concentration based on X-ray fluorescence (XRF) measurements. The element ratios were used as proxies for sediment composition and as paleo-environmental indices. In sediment physical properties, δ18O values, and geochemical properties, evidence for glacial and interglacial cycles and spectral periods of 405, 100, 41 ka were found. A shift of the spectral period from 41 to 100 ka took place in sediment cores during (1.4 to 0.4 Ma). Numerical ages obtained from tephra layers included in the sedimentary record enabled to estimate sedimentation rates from both cores. Although both drill sites are only 1800 m away from each other, sedimentation rates of 2.15 to 2.96 cm ka−1 (GeoB 20824–4) and 5.49 to 6.77 cm ka−1 (GeoB 20846–1), respectively, differ by a factor of two. This may be the reason why two facies-units were identified in core GeoB 20824–4, whereas sediments of core GeoB 20846–1 all belong to the same facies. A change of lithofacies in core GeoB 20824–4 between Unit I and Unit II in ∼20 mbsf at 1.5 to 1.4 Ma marks the initiation of the EMPT.

USING RADIOISOTOPE METHODS TO DATE Cs INFLOW TO BOTTOM SEDIMENTS OF THE YENISEI RIVER

The long-term study of samples of bottom sediments (BS) of the Yenisei River revealed the presence of a unique set of artificial radionuclides (Co, Cs, Eu, Eu), which made it possible to combine different methods for calculating sedimentation rates for a retrospective assessment of river BS. Studies have been carried out to determine the sedimentation rates by various methods, using natural non-equilibrium Pb, the ratios of artificial isotopes Cs/Co and Eu/Eu, and marker Co, in several sections of the Yenisei River - downstream of the radioactive discharges of the Mining and Chemical Combine (MCC) of Rosatom near the villages of B. Balchug and Atamanovo, as well as upstream of the MCC discharges in the reference areas near the villages of Esaulovo and Shivera. Estimation of sedimentation rates using non-equilibrium Pb, Cs/Co and Eu/Eu isotope ratios, and marker Co for reference areas and the areas near villages located downstream of the MCC showed that their values lay in the range of 0.5-1.3 cm/year. A chronology of Cs influx into BS was constructed using different radioisotope methods, which demonstrated that the maximum Cs influx into BS in the reference regions of the villages of Esaulovo and Shivera and in areas of the village of B. Balchug was noted during the extreme flood of 1966. Cs maxima were also found in the BS layers whose dating coincided with the floods of 1988 and 1995-1997.

SEDIMENTARY DEPOSITION OF METALS IN SEDIMENTS FROM ILHA GRANDE BAY, RJ (BRAZIL)

The industrial development of coastal regions in recent decades and the lack of studies of these systems have led to the need to develop studies on metal contamination that distinguish impacted areas from conserved areas and which can be used to evaluate contamination processes through the study of historical records of deposited material. In the present study, geochemical sedimentary analysis predicts the evolution of the entry and behavior of metals in the Enseada do Abrão in Ilha Grande Bay. Sedimentary evidence was collected to assess concentrations of metals and organic matter and to correlate them with factors possibly controlling their deposition, identifying their respective sources. Furthermore, through 210Pb dating, the deposition of both metals and organic matter in recent decades can be monitored. To this end, analyses of basic compounds (total organic carbon and total nitrogen) and metals (Al, Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn) were performed. The data obtained were normalized using Al as the reference element, and average values for shale were used as a baseline for enrichment factors and to calculate the geoaccumulation index. It was possible to estimate sedimentation rates and metal fluxes through 210Pb dating. It could be observed that despite increasing development the analyzed sediments did not have increased concentrations of metals. Furthermore, the concentrations of the elements studied were found to be below the values ​​found in affected areas. Al did not show correlations with other metals, and the enrichment factor did not show increased concentrations of metals in the most recent layers, nor were there many values ​​that would suggest enrichment originating from anthropogenic contribution throughout the studied profile. Based on the values ​​of IGeo, it can be observed that the metals present are within their baseline levels and do not exhibit a significant anthropogenic contribution. The metal fluxes did not show increasing values. These evaluations suggest the absence of contamination in the studied area, and the area can thus still be considered to be one not impacted by metals of anthropogenic origin. This discovered record is useful as a basis for monitoring activities that have expanded in recent decades.

Paleo Environmental Pollution Assessment of Erdek and Bandırma Bays in the Sea of Marmara, Türkiye

ABSTRACT Geochemical and sedimentological analyses and C-14 dating of four cores from Erdek and Bandırma Bays were performed to evaluate the metal pollution, history and sources, and content in the southern Sea of Marmara (SoM) caused by industrial, agricultural and domestic activities during the sediment deposition. The selected elements’ pollution (Al, Fe, Mn, As, Co, Cr, Cu, Hg, Ni, Pb, V and Zn) data were evaluated using contamination factor (CF) and pollution load index (PLI). The sedimentary succession in all cores consists mainly of clay (9–96%), silt (1–78%) and sand (0.1–20%) with small amounts of gravel (0.1–7%). The results of CF and PLI reveal that the upper 20 cm core sediments in Erdek Bay were contaminated with Hg (0.07–1.1 mg/kg), Pb (4–72 mg/kg) and Zn (12–255 mg/kg) by both anthropogenic and lithogenic input via the Biga and Gönen streams. Furthermore, the upper 20 cm of MD72 and BK1 core sediments were moderately polluted with As, Cu, Hg, Pb and Zn caused by the discharge of untreated industrial wastewater and domestic sewage from the surrounding area of Bandırma Bay. Moreover, lithogenic Pb-Zn was transported to Erdek Bay by Biga and Gönen streams from the Pb-Zn mineralized zones in the southern SoM drainage area. C-14 dating reveals that As, Hg, Pb and Zn contamination in the study area was started about 400–500 years before the present based on preliminary sedimentation rate estimates and has increased intensely in the last century. Our work is a significant effort to help the environment protection agency or other stakeholders draw a framework to solve this emerging challenge from sewage and wastewater treatment plants.

Sedimentary Pyrite Formation in a Seasonally Oxygen‐Stressed Estuary: Potential Imprints of Microbial Ecology and Position‐Specific Isotope Fractionation

AbstractSedimentary pyrite records are essential for reconstructing paleoenvironmental conditions, but these records may be affected by seasonal fluctuations in oxygen concentration and temperature, which can impact bioturbation, sulfide fluxes, and distributions of sulfide oxidizing microbes (SOMs). To investigate how seasonal oxygen stress influences surficial (&lt;2 cm) pyrite formation, we measured time‐series concentrations and sulfur isotope (δ34S) compositions of pyrite sulfur along with those of potential precursor compounds at a bioturbated shoal site and an oxygen‐deficient channel site in Chesapeake Bay. We also measured radioisotope depth profiles to estimate sedimentation rates and bioturbation intensities. Results show that net pyrite precipitation was restricted to summer and early autumn at both sites. Pyrite concentration was higher and apparently more responsive to precursor compound concentration at the mildly bioturbated site than at the non‐bioturbated site. This disparity may be driven by differences in the dominant SOM communities between the two sites. Despite this, the sites' similar pyrite δ34S values imply that changes in SOM communities have limited effects on surficial pyrite δ34S values here. However, we found that pyrite δ34S values are consistently and anomalously lower than coeval precursor compounds at both sites. A steady‐state model demonstrates that equilibrium position‐specific isotope fractionation (PSIF) effects in the S8‐polysulfide pool can create a 4.3–7.3‰ gap between δ34S values of pyrite and zero‐valent sulfur. This study suggests that SOM communities may have distinct effects on pyrite accumulation in seasonally dynamic systems, and that PSIF in the polysulfide pool may leave an imprint in pyrite isotope records.

Reconstruction of Lake-Level Changes by Sedimentary Noise Modeling (Dongying Depression, Late Eocene, East China)

The late Eocene succession of the Dongying Depression forms a highly productive hydrocarbon source. However, due to lack of an unambiguous fine chronostratigraphic framework for the late Eocene stratigraphy, it is challenging to understand the paleolake’s evolution and the driven mechanism of lake-level variation, a limitation which hinders hydrocarbon exploration. In this work, high-resolution gamma-ray logging data were analyzed to carry out the cyclostratigraphic analysis of the third member (Es3) of the Shahejie Formation in the Dongying Depression. Significant 405-kyr eccentricity cycles were recognized based on time series analysis and statistical modeling of estimated sedimentation rates. We abstracted ~57 m cycles of the GR data in the Es3 member, which were comparable with the long eccentricity cycles (~405-kyr) of the La2004 astronomical solution, yielding a 6.43 Myr long astronomical time scale (ATS) for the whole Es3 member. The calibrated astronomical age of the third/fourth member of the Shahejie Formation boundary (41.21 Ma) was adopted as an anchor point for tuning our astrochronology, which provided an absolute ATS ranging from 34.78 ± 0.42 Ma to 41.21 ± 0.42 Ma in Es3. According to the ATS, sedimentary noise modeling for the reconstruction of lake-level changes was performed through the late Eocene Es3. The lake-level changes obtained based on sedimentary noise modeling and spectrum analysis reveal significant ~1.2 Myr cycles consistent with global sea level variations which were related to astronomical forcing. Potential driven mechanisms of marine incursion and/or groundwater table modulation were linked to explain the co-variation of global sea level changes and regional lake level changes. Our results suggest global sea level fluctuations may have played an important role in driving the hydroclimate and paleolake evolution of the late Eocene Dongying Depression.

Lower to Middle Miocene multiproxy biostratigraphy of the P-18 core-stratigraphic well in Sinú-San Jacinto Basin, Caribbean region of Colombia

A Lower-to-Middle Miocene core-stratigraphic section, P-18 well, was drilled in the Sinú-San Jacinto Basin (SSJB) in the Caribbean region of Colombia, showing exceptionally well-preserved planktonic foraminifera, calcareous nannofossils, and palynomorphs. We use these micropaleontological groups to perform integrated biostratigraphic analyzes and estimate the stratigraphic record's continuity and sedimentation rates for the early Neogene of the region. Two lithological intervals were defined, the first between 423.9 m and 345.8 m and the second between 345.8 m to the top of the core. Only palynomorphs were identified for the first interval of this section, assigned to the Ciénaga de Oro Formation. We proposed an age no older than 19.49 Ma (Early Miocene, Burdigalian) based on the occurrence of Rugutricolpites intensus at 381.5 m. Although for the second interval, correlated with the Porquera Formation, we found three well-calibrated bioevents of calcareous microfossils, top of Sphenolithus belemnos at 213.2 m, base of Sphenolithus heteromorphus at 187.9 m, and top of Catapsydrax dissimilis at 141.9 m. In addition, we identified the top of uncalibrated planktonic foraminifera Trilobatus primordius, Globigerinoides altiaperturus, Paragloborotalia semivera, Paragloborotalia acrostoma, and Globoturborotalita pseudopraebulloides. Our age model along the P-18 well indicates a time range from ≥19.01 Ma (Early Miocene, Burdigalian) to ∼14.70 Ma (Middle Miocene, Langhian) equivalent to the calcareous nannofossils biozones NN3 to NN4, or, M3 to M5? Of planktonic foraminifera or palynological zones from T12 to T14? Even though we do not observe standard Middle Miocene bioevents with well-calibrated ages, the occurrence of nannofossils taxa Helicosphaera ampliaperta, and planktonic foraminifera Paragloborotalia semivera, Paragloborotalia acrostoma, and Globoturborotalita pseudopraebulloides show a distinctive biostratigraphic pattern, suggesting an age of ∼14.70 Ma to the top of the core section. Estimated sedimentation rates display high values (∼120 m/Myr to ∼219 m/Myr) during the Burdigallian (Early Miocene). They coincide with the regional subsidence increase during the Early Neogene in SSJB and Lower Magdalena Valley and the Early Miocene marine flooding event recorded in the Eastern Llanos Basin (ELB). From 17.60 Ma onwards, sedimentation rates decrease considerably, and a hiatus between 17.54 Ma and 16.96 Ma is interpreted as being tied to an abrupt change in sedimentology from calcareous mudrocks (marls) to very fine sandstones and sandy limestones. Finally, our data suggest that sedimentation rates in the basin were higher than marine sedimentation for ODP 999 during the same period.

Use of 210Pb and 137Cs radionuclides as simple method of estimating sedimentation rates on reservoir

Use of 210Pb and 137Cs radionuclides as simple method of estimating sedimentation rates on reservoir

Present and Future Losses of Storage in Large Reservoirs Due to Sedimentation: A Country-Wise Global Assessment

Reservoir sedimentation is often seen as a site-specific process and is usually assessed at an individual reservoir level. At the same time, it takes place everywhere in the world. However, estimates of storage losses globally are largely lacking. In this study, earlier proposed estimates of sedimentation rates are applied, for the first time, to 47,403 large dams in 150 countries to estimate cumulative reservoir storage losses at country, regional, and global scales. These losses are estimated for the time horizons of 2022, 2030, and 2050. It is shown that 6316 billion m3 of initial global storage in these dams will decline to 4665 billion m3 causing a 26% storage loss by 2050. By now, major regions of the world have already lost 13–19% of their initially available water storage. Asia-Pacific and African regions will likely experience relatively smaller storage losses in the next 25+ years compared to the Americas or Europe. On a country level, Seychelles, Japan, Ireland, Panama, and the United Kingdom will experience the highest water storage losses by 2050, ranging between 35% and 50%. In contrast, Bhutan, Cambodia, Ethiopia, Guinea, and Niger will be the five least affected countries losing less than 15% of storage by 2050. The decrease in the available storage by 2050 in all countries and regions will challenge many aspects of national economies, including irrigation, power generation, and water supply. The newly built dams will not be able to offset storage losses to sedimentation. The paper is an alert to this creeping global water challenge with potentially significant development implications.

Increased levels of forestry best management practices reduce sediment delivery from Middle and Lower Coastal Plain clearcut harvests and access features, southeastern states, USA

Over 390,000 ha of forestland are clearcut annually (1–2%) across the Coastal Plain region of the southeastern U.S. where forestland occupies approximately 30 million hectares in the region. Extensive periods of high-water tables, wet-weather and harvesting, rutting, erodible soils, and drainage networks typical of the Coastal Plain increase the potential for erosion and stream sedimentation. To mitigate these impacts, water quality forestry Best Management Practices (BMPs) were developed for erosion and sediment control and are recommended and approved by all southeastern state forestry agencies for application during and after harvests. The goal of this study was to estimate erosion and sedimentation from silvicultural operations in the Coastal Plain under three different and previously recognized levels of BMP implementation including BMP– (<80%), BMP-standard (80%–90%), and BMP+ (>90%), where 90% represents average implementation. A total of 35 recent clearcut sites were evaluated in the Coastal Plain of 12 southeastern states. Erosion was estimated via the USLE-Forest model at five operational features, including decks, stream crossings, haul roads, skid trails, and harvest areas only, which were classified into one of three BMP levels. Sediment traps were utilized on a subset of Coastal Plain sites in Virginia and North Carolina so that sediment delivery ratios (unitless) could be calculated. Clearcut area estimates were obtained from the United States Forest Service (USFS), Forest Inventory and Analysis (FIA) Program. The percent areas comprised within each operational feature were multiplied by total clearcut areas in the Coastal Plain region so that erosion and sedimentation estimates could be expanded to a regional scale. Examination of the different levels of BMP implementation revealed estimated sedimentation rates of 0.5 Mg ha−1 yr−1 and 0.4 Mg ha−1 yr−1 at the BMP-standard and BMP+ levels, respectively. The range of overall estimated sediment masses at the BMP-standard and BMP+ levels most accurately reflects the current state of BMP application in the Coastal Plain. BMPs were most obviously effective at mitigating erosion and potential sediment delivery from Coastal Plain skid trails and haul roads. The highest level of BMP implementation (BMP+) at forest roads and skid trails mitigated approximately 95% of sediment compared to BMP–. Overall sediment removal efficiencies were 77% for BMP-standard and 83% for BMP+ respectively when compared to BMP–. Conclusively, this study demonstrates that forestry BMPs are highly effective at mitigating erosion and stream sedimentation when appropriately applied in the southeastern Coastal Plain.

&lt;i&gt;Corrigendum to&lt;/i&gt;: Constraining nitrogen sources to a seagrass-dominated coastal embayment by using an isotope mass balance approach

Nitrogen (N) is often the key nutrient limiting primary production in coastal waters. Quantifying sources and sinks of N is therefore critical to understanding the factors that underpin the productivity of coastal ecosystems. Constraining nitrogen inputs can be difficult for some terms such as N fixation and marine exchange as a consequence of uncertainties associated with scaling and stochasticity. To help overcome these issues, we undertook a N budget incorporating an isotope and mass balance to constrain N sources in a large oligotrophic coastal embayment (Western Port, Australia). The total N input to Western Port was calculated to be 1400Mg Nyear&lt;sup&gt;&amp;#x2212;1&lt;/sup&gt;, which is remarkably consistent with previous estimates of sedimentation rates within the system. Catchment inputs, N fixation, marine sources and atmospheric deposition comprised 44, 28, 28 and 13% of N inputs respectively. Retention of marine-derived N equated to ~3 and ~10% of total N and NO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; flushed through the system from the marine end-member. The relatively high contribution of N fixation compared with previous studies was most likely to be due to the high proportion of nutrient-limited intertidal sediments where N is mediated by seagrasses and sediment cyanobacteria.

Astronomically forced cycles in Middle Permian fluvial sediments from Karoo Basin (South Africa)

We report evidence for Milankovitch cycles discovered in Middle Permian strata of the fluvial Abrahamskraal formation, lower Beaufort Group, in Karoo Basin of the Northern Cape Province, South Africa. Statistical analyses of ranked lithologies and of major element oxides have been used to obtain clusters of elements that capture lithological variations and reflect changes of the sedimentary environment through time. Spectral analysis of these elemental statistical groups reveal significant meter-scale sedimentary cycles of 67 m, 17.5 m, 5.9 m and 3.5–2.8 m, which can be interpreted as the sedimentary expression of astronomical forcing, based on the available estimate of sedimentation rate. The identified periods of short-eccentricity, precession and obliquity show a good match with those predicted for Middle Permian times, providing a data-based validation of the astronomical theory. Cycle counting integrated with available UPb dating, provides a cyclochronological calibration for Wordian normal magnetozones and, combined with radiometric ages, indicates an age of 266.5 ± 0.26 Ma for the end of Kiaman superchron. Recognition of the orbitally driven sedimentation in Gondwana supercontinent suggest a global extension of astronomical influence of Permian climate and confirms empirical knowledge of Earth's astronomical parameters before 260 million years ago. The new data demonstrate a rare case of astronomically paced cyclicity in fluvial deposits and a unique cyclostratigraphic record of the Middle Permian Gondwana supercontinent whose sedimentation reflects orbitally-paced precipitation changes.