Terrestrial Components Research Articles

Replenishment characteristics of riparian debris baits to rivers and the response to flow

The riparian zone is a crucial interface between the aquatic and terrestrial components of river ecosystems. Organic matter deposited here can serve as an important food source for aquatic organisms, earning it the name of detritus bait. The construction of hydrological facilities has altered the flow rhythms of rivers, reducing the inundated area of banks and the frequency of flow velocity changes, which in turn negatively affects the ecological stability of the river. Given these reasons, it is crucial to understand the distribution characteristics of debris bait on riparian and the recharge pattern to rivers under flow impacts. The physical properties intrinsic to the debris in question were examined in order to ascertain their influence on the dynamics of debris transport through natural sampling methods. The distribution patterns of debris on natural river banks were investigated using density separation. A quantitative experimental model was designed based on the results of natural investigations to analyze the response characteristics of debris in-stream recharge to hydrodynamic structures at different flow velocities. The results indicate that the debris distribution is influenced by the background soil situation and flow effect. The soil layer immediately adjacent to the surface of the bank has a higher recharge effect. The main period for riparian debris recharge occurs at the onset of changes in flow rate. Furthermore, there is a positive correlation between the flow velocity and the quantity of debris entering the river. The findings of this study offer valuable insights into the replenishment of river bank debris bait under the current conditions, with implications for the ecological management of rivers undergoing hydropower development.

Response of the bGeigie Nano and CzechRad Monitors to Secondary Cosmic Radiation.

Ambient dose rate surveying has the objective, in most cases, to quantify terrestrial radiation levels. This is true in particular for Citizen Monitoring projects. Readings of detectors, which do not provide spectrally resolved information, such as G-M counters, are the sum of contributions from different sources, including cosmic radiation. To estimate the terrestrial component, one has to subtract the remaining ones. In this paper, we investigate the cosmic response of two particular monitors, the bGeigie Nano, which has been used extensively in the Safecast Citizen Monitoring project, and its upgraded version, the new CzechRad, which uses the same G-M detector, and show how the local contribution of cosmic radiation can be estimated.

Accurate and Efficient Numerical Simulation of Land Models Using SUMMA With SUNDIALS.

Numerical simulation of land models without error control can be highly inaccurate. We present the incorporation of the Suite of Nonlinear and Differential-Algebraic Equation Solvers (SUNDIALS) package to solve the equations that simulate thermodynamics and hydrologic processes in the Structure for Unifying Multiple Modeling Alternatives (SUMMA) land model. The algorithmic features of SUNDIALS, such as error estimation and adaptive order and step-size control, result in a SUMMA-SUNDIALS model that delivers substantially improved accuracy and relative computational efficiency compared to integration with the previous SUMMA model, which uses the low-order backward Euler method with no rigorous error control. The results are demonstrated through simulations over the North American continent with more than 500,000 spatial elements. Compared to the previous SUMMA model, we find that the simulations produced by the SUMMA-SUNDIALS model are orders of magnitude closer to converged solutions for the same computational cost. Being able to efficiently perform more reliable simulations makes the SUMMA-SUNDIALS model a powerful tool for improving our understanding of the terrestrial component of the Earth System.

Morphological and Hydrogeological Controls of Groundwater Flows and Water Age Distribution in Mountain Aquifers and Streams

AbstractMountains are an essential source of the terrestrial component of the hydrological cycle, supplying high‐quality water to river networks and floodplain aquifers, especially during droughts. Traditionally, mountain hydrology has focused on shallow processes, overlooking the significance of deep‐seated rock formations due to characterization challenges. Recent field studies have revealed that fractured rock formations can host rich aquifers despite their low permeability. Nonetheless, it is unclear how deep flows interact with the overall hydrological functioning of mountain areas, how they contribute to the long‐term water budget, and how climate, morphology, and geology jointly control them. Through numerical simulations, we have gained new insights into mountain aquifers, addressing (a) the proportion of groundwater base flow and its age distribution, (b) water storage and its sensitivity to groundwater recharge, (c) the impact of long term mean recharge on the extent of the groundwater‐fed surface drainage network under various morphological and geological settings. We showed that subsurface travel times follow a Gamma distribution, whose parameters are modulated by recharge, hydraulic conductivity, and topography. High recharge and strong decay with depth of the hydraulic conductivity in a hilly topography lead to a shallow water table mimicking the surface topography and spatially distributed low‐intensity outflows that feed a dense drainage network. In rugged catchments, the groundwater contribution intensifies and concentrates in the downstream portion of the river network as recharge declines. These findings can help assess how a changing climate might impact hydrological regimes under various geomorphological conditions and identify sustainable water uses in mountain environments.

Estimating soil moisture from environmental gamma radiation monitoring data

AbstractSoil moisture (SM) information is invaluable for a wide range of applications, including weather forecasting, hydrological and land surface modeling, and agricultural production. However, there is still a lack of sensing information that adequately represents root‐zone SM for longer periods and larger spatial scales. One option for root‐zone SM observation is terrestrial gamma radiation (TGR), as it is inversely related to SM. Hence, the near real‐time data of more than 5000 environmental gamma radiation (EGR) monitoring stations archived by the EUropean Radiological Data Exchange Platform (EURDEP) is a potential source to develop a root‐zone SM product for Europe without extra investments in SM sensors. This study aims to investigate to what extent the EURDEP data can be used for SM estimation. For this, two EGR monitoring stations were equipped with in situ SM sensors to measure reference SM. The terrestrial component of EGR was extracted after eliminating the contributions of rain washout and secondary cosmic radiation, and used to obtain a functional relationship with SM. We predicted the weekly volumetric SM with a root mean square error of 7%–9% from TGR measurements. Nevertheless, we believe that this technique, due to its greater penetration depth and long data legacy, can provide useful data complementary to satellite‐based remote sensing techniques to estimate root‐zone SM at the continental scale.

Organic geochemistry and 1D-basin modeling in the Taranaki Basin, New Zealand: Implications for deltaic-source rocks of the cenozoic oil and condensate reservoirs

The Taranaki Basin in New Zealand is an area of active exploration for oil and condensate. This research focuses on integrating geochemical characteristics and 1-D basin modeling to Late Cretaceous to Miocene source rock systems, along with oil and condensate data from fifty-seven wells in the Taranaki Basin. The geochemical study reveals that the oil and condensate samples were generated from clay-rich source rocks, containing mixed organic matter, with large amounts of terrestrial organic matter input. These source rocks were deposited in fluvial to fluvio-deltaic environments under oxic conditions. The presence of oleanane in both oil and condensate samples suggests that the source rocks had a significant terrestrial component and deposited during the Late Cretaceous to Cenozoic. Using various biomarker proxies, oil-source rock correlation along with 1-D basin modeling revealed that the oil and condensate were mainly derived from the Late Cretaceous Rakopi and Paleocene Farewell formations at different maturity stages. The oils were generated within the peak-mature oil window, while the condensates primarily resulted from the secondary cracking of oil taking place in the source rock within the gas generation window. This finding is consistent with the 1-D basin modeling results. The model shows that the Paleocene Farewell source rock has achieved the primary stage of oil generation (0.55–0.95 Easy %Ro), contributing to most of the discovered oils in the Cenozoic reservoir rocks. Meanwhile, the Late Cretaceous Rakopi source rock reached the gas window with a higher vitrinite reflectance of more than 1.30 Easy %Ro, indicating greater gas generation potential.

A critical assessment of geological weighing lysimeters: Part 2—Modelling field scale soil moisture storage and hydrological fluxes

AbstractLand surface models (LSMs) are used to simulate the terrestrial component of water, energy, and biogeochemical cycles. These simulations are useful for water resources management, drought and flood prediction, and numerical climate/weather prediction. However, the usefulness of LSMs are dependent by their ability to reproduce states and fluxes realistically. Accurate measurements of water storage are useful to calibrate and validate LSMs outputs. Geological weighing lysimeters (GWLs) are instruments that can provide field‐scale estimates of integrated total water storage within a soil profile. We use field estimates of total water storage and subsurface storage to critically evaluate two different land surface models: the Modélisation Environnementale communautaire—Surface Hydrology (MESH) which uses the Canadian Land Surface Scheme (CLASS), and the Structure for Unifying Multiple Modeling Alternatives: (SUMMA). These models have differences in how the processes and properties of the land surface are represented. We attempted to parameterize each model in an equivalent manner, to minimize model differences. Both models were able to reproduce observations of total water storage and subsurface storage reasonably well. However, there were inconsistencies in the simulated timing of snowmelt; depth of soil freezing; total evapotranspiration; partitioning of evaporation between soil evaporation and evaporation of intercepted water; and soil drainage. No one model emerged as better overall, though each model had specific strengths and weaknesses that we describe. Insights from this study can be used to improve model physics and performance.

Recycling the rain: Exploring forest management practices in a western Mediterranean watershed to recouple the atmospheric and terrestrial water cycle

Current knowledge of the role that forests play in recycling rainwater has led to the proposal of forest management practices to mitigate desertification in the western Mediterranean basin. Building upon this hypothesis, we present the Mijares watershed in eastern Spain as a detailed case study. We then perform a scientific literature review in the context of the western Mediterranean basin to identify the physical and biophysical uncertainties associated with forest management practices that aim to strengthen the atmospheric and terrestrial components of the water cycle. The review identified eleven interconnected uncertainties that result from complex vegetation, climate, soil, and water relationships. We discuss the need to deepen our understanding of the atmospheric dynamics of the Mijares by accounting for the role of forests in recycling rainfall and by adopting an adaptive management approach to apply the lessons learned in the territory. Based on these considerations, we propose forest management practices to reinforce the water cycle of the watershed. Our work contributes to understanding the uncertainties arising from forest management practices aimed at mitigating desertification, thereby supporting decision-making. These insights apply to other western Mediterranean coastal watersheds.

The study of radionuclide activities in the sediments of deep areas of Skagerrak and Southern Baltic

This study investigates the activities of radionuclides (137Cs, 210Pb, 214Pb, 239,240Pu, and 40K), carbon isotopes (δ13C and 14C), and grain size compositions in surface bottom sediments across the southern Baltic and Skagerrak Strait. Our findings reveal significant connections between these parameters and their dependence on sediment transport dynamics. The distribution patterns of natural and artificial radionuclides were studied to understand the factors influencing their transport to the deep areas. The results show that 137Cs activity in surface bottom sediments (0–5 cm) ranges from 8 to 11 Bq/kg in the Skagerrak area and reaches 220 Bq/kg in the southern Baltic, closer to the vicinity of river discharges. The activity ranges of 239,240Pu are similar between the study areas, but the mean value at the Skagerrak site is higher at 1.6 Bq/kg. The transport of 210Pbex to the bottom is mainly dependent on the number of fine particles (0–20 μm) in the water column, while the transport of 137Cs primarily driven by scavenging by marine organics from the water column. In the southern Baltic, a strong correlation indicates that a significant share of 137Cs most likely originates from fluvial input. The particle size distribution reflects calm conditions in the deep waters, while in the Curonian Lagoon reference areas there are pronounced contrasts between stations with strong and calm hydrodynamic conditions. The δ13C values in the surface bottom sediments decrease towards river discharge areas, reflecting an increased terrestrial component of the organic fraction, and the number of coarse particles also increases.

The effects of kelp powder and fucoidan on the intestinal digestive capacity, immune response, and bacterial community structure composition of large yellow croakers (Larimichthys crocea)

Feed terrestrial components can induce intestinal stress in fish, affecting their overall health and growth. Recent studies suggest that seaweed products may improve fish intestinal health. In this experiment, three types of feed were prepared: a basic diet (C group), a diet with 0.2 % fucoidan (F group), and a diet with 3 % kelp powder (K group). These diets were fed to large yellow croaker (Larimichthys crocea) over an 8-week period. Each feed was randomly assigned to three seawater cages (4.0 m × 4.0 m × 5.0 m) containing 700 fish per cage. The study assessed changes in growth and intestinal health, including intestinal tissue morphology, digestive enzyme activities, expression of immune-related genes, and bacterial community structure. Results showed that incorporating seaweed products into the diet improved the growth and quality traits of large yellow croakers and significantly enhanced their intestinal digestive capacity (P < 0.05). Specifically, the 0.2 % fucoidan diet significantly increased the intestinal villus length and the activities of digestive enzymes such as trypsin, lipase, and α-amylase (P < 0.05). The 3 % kelp powder diet significantly enhanced the intestinal crypt depth and the activities of trypsin and lipase (P < 0.05). Both seaweed additives significantly enhanced intestinal health by mitigating inflammatory factors. Notably, the control group's biomarkers indicated a high presence of potential pathogenic bacteria, such as Streptococcus, Pseudomonas, Enterococcus, Herbaspirillum, Neisseria, Haemophilus, and Stenotrophomonas. After the addition of seaweed additives, these bacteria were no longer the indicator bacteria, while the abundance of beneficial bacteria like Ligilactobacillus and Lactobacillus increased. Significant reductions in the expression of inflammatory factors (e.g., il-6, tnf-α, ifn-γ in the fucoidan group and il-8 in the kelp powder group) further supported these findings. Our findings suggested that both seaweed additives helped balance intestinal microbial communities and reduce bacterial antigen load. Considering the effects, costs, manufacturing, and nutrition, adding 3 % kelp powder to the feed of large yellow croaker might be preferable. This study substantiated the beneficial effects of seaweed on the aquaculture of large yellow croaker, particularly in improving intestinal health. These findings advocated for its wider and more scientifically validated use in fish farming practices.

Anatomy of the late Famennian Dasberg event in a deep shelf of southern Euramerica: Oxygenation and productivity in a restricted basin during a progressive long-term cooling

The late Famennian Dasberg event is described as a series of global hypoxic and transgressive events associated with global faunal turnover. The event, recorded on a deep shelf of the Rhenohercynian basin from southern Euramerica, was investigated in the Holy Cross Mountains of Poland using integrated high-resolution geochemical, mineralogical, and palynological studies. The data revealed the progressive restriction of the intrashelf basin resulting from intense regional block tectonics likely connected with the Late Devonian Variscan tectonic activity. This led to weak chemocline ventilation, the development of anoxic conditions, and the deposition of two organic-rich Dasberg black shale (DBS) horizons. The DBS was deposited in an environment characterized by the constant contribution of detrital components from a common source area. A slight change in terrestrial input may have been driven by modest bathymetric changes associated with the tectonics and stronger winds delivering charcoal and terrestrial components (i.e., miospores and phytoclasts). A supply of nutrients from land and delivery of crucial biolimiting elements (i.e., nitrogen and phosphorus) from deeper waters stimulated primary productivity, as recorded in phytoplankton blooms. The δ13Corganic values in the DBS reflect the incorporation of primary biomass from mainly marine photoautotrophs into sedimentary organic matter. Episodic delivery of toxic sulphides to the photic zone was detected by small-sized framboids and biomarkers, which record the appearance of green sulphur bacteria that photosynthesized in euxinic water column. The activity of phototrophic sulphide-oxidizing bacteria could have led to hyper-enrichment of Zn (715–1002 ppm) in the Lower DBS. The diachronous appearance of the DBS horizons in Euramerica and Gondwana, and regionally marked extinction of benthic fauna, suggest that anoxia developed in restricted Black Sea–like basins formed by intensive tectonic activity and continental plate convergence.

Influence of large wood dynamics on flow and channel morphology in a forest stream

The riparian zone is a dynamic ecosystem formed by the interaction of aquatic and terrestrial components of rivers and serves as a source of the large wood (LW). We aimed to understand the LW dynamics and the LW influence on river morphology, sediment distribution, and flow velocity within three reaches of a low-order stream. The study was performed in a segment (770 m in length) of the Perdizes stream, located in Aparados da Serra National Park, southern Brazil. We framed the study by focusing three issues: i) the processes explaining the LW dynamics in the Araucaria Forest biome; ii) the effects of LW on the flow velocity along the study reaches, and iii) the presence of LW affecting the sediment longitudinal connectivity. The methodology consisted of: (i) collection of hydrological data (rainfall, discharge, and streamflow velocity), (ii) Perdizes stream characterization by topo-bathymetric survey and river-flow simulation with HEC-RAS 5.0.7 1D. and (iii) detailed field surveys of LW and bed sediments. The LW descriptions were performed at four moments (July 10, 2019; November 19, 2019; July 24, 2020; and December 18, 2020). Abundant LW, mainly from araucaria (Araucaria angustifolia (Bertol.) Kuntze), was observed before meanders. A notable reduction in LW volume and an increased proportion of araucaria, compared to deciduous trees, were observed within the channel. Mass balance analysis indicated fluctuations in riparian vegetation biomass, emphasizing the connectivity between vegetation and the river. Streamflow velocity decreased in LW presence, from occurrence to the margin. Bed sediment diameters were consistently smaller in cross-sections with LW presence. The accumulation of smaller sediments with LW indicated partial downstream sediment disconnectivity. HEC-RAS simulations confirmed increased LW deposition in lower velocity zones. This understanding of fluvial dynamics contributes to effective natural environment management, especially in the Araucaria Forest context.

Increased dominance of terrestrial component in dissolved organic matter in Chinese lakes

The source composition of chromophoric dissolved organic matter (CDOM) in lakes is closely related to regional environmental changes, human activities, and the carbon cycle. The spectral slope ratio (SR) is an important parameter of CDOM optical components, and combined with remote sensing technology, the source composition of CDOM can be tracked comprehensively and efficiently in large regions. Here, we proposed a CDOM source tracking remote sensing model (CDOM-SR) based on the hue angle (α) to assess the spatial pattern and long-term trend of the CDOM source composition in Chinese lakes (surface area ≥ 1 km2) from 1986 to 2021. Validation results show that the CDOM-SR model has a good SR estimation performance with a median absolute percentage difference, root mean square deviation, median ratio, and median deviation of 17.91 %, 0.23, 1.02, and 0.03, respectively. We found that the average SR of Chinese lakes presents an obvious spatial pattern of high in the west and low in the east due to the difference in human activity intensity and the natural geographical environment. Additionally, we found that the average SR of Chinese lakes from 1986 to 2021 decreased at a rate of - 0.06/10 years, of which 64.37 % of lakes decreased significantly, 15.42 % of lakes had no significant change, and only 20.20 % of lakes increased. The widespread decrease in the average SR indicates that the increasing human activity discharge of terrestrial organic matter has had an important impact on the source composition of the CDOM in Chinese lakes. Our results provide a new resource for remote sensing monitoring of CDOM sources and important insights into lake carbon cycling under the influence of ongoing human activities.

Systematic Review on Prediction and Monitoring of Climate Change

Climate change poses a severe and very bad threat to human society and global ecosystems, necessitating careful planning, monitoring, and forecasting. This paper reviews spread a range of monitoring techniques and predictive models to better understand, anticipate, and mitigate the effects of climate change. Predictive models combine a wide and large range of methods, from statistical and machine learning-based models to complex Earth system models that integrate atmospheric, oceanic, and terrestrial components. These models look at historical data of history, greenhouse gas emissions, and various climate drivers to anticipate future climatic scenarios. Tracking changes in temperature, precipitation patterns, sea level rise, and other climate change indicators over time also requires the use of monitoring tools that include satellite observations, ground-based sensors, and remote sensing technology.. Creating sustainable behaviors to counteract the negative consequences of climate change, educating politicians, and integrating reliable monitoring systems and predictive models all help in the development of adaptive systems. To address the complexities, difficulties, and breakthroughs in climate change prediction and monitoring, scientists, policymakers, and stakeholders should work together.

Don't take my trees: Re‐evaluating the importance of trees when it comes to managing green and golden bell frog, Litoria aurea, habitat

AbstractIt is vital to identify habitats used by each life stage of a species to formulate effective conservation management and restoration guidelines. For the threatened green and golden bell frog, Litoria aurea, it is currently recommended that, to prevent waterbody shading, managed or constructed habitat for the species should not include trees. Shading has been reported to prevent adults from sun basking, reduce breeding activity, and lower water temperatures, which may impede tadpole growth and development and provide optimum conditions for the amphibian chytrid pathogen, Batrachochytrium dendrobatidis. However, the complete exclusion of trees, which are naturally present in L. aurea habitat, warrants evidence that supports this recommendation. In the present study, we used a multi‐year dataset on an L. aurea population on Kooragang Island, NSW, Australia to determine the occurrence of tree use by post‐metamorphic individuals. These data included information on nearly 12 500 individuals captured from 86 waterbodies across 8 consecutive breeding seasons. We found that tree use by juveniles, adult males, and adult females was widespread and common, occurring both during the day and night, with more than one out of every 20 individuals captured in trees. Our findings suggest that trees are a potentially important attribute of the terrestrial component of wetland habitats occupied by L. aurea. We hypothesize that trees may (i) create microhabitat for foraging and/or increased diversity of prey species, (ii) provide refuge from predators, and (iii) allow sun basking off the ground, thereby offering protection against the chytrid fungus while removing them from chytrid‐prevalent environments such as water and moist soils. We call for the careful reconsideration of tree exclusion within L. aurea habitat and further research into the benefits of allowing trees to grow near waterbodies to accommodate the ecological needs of this threatened species.

A Review of the Publications on Carbon Isotopes in Groundwater and Rainwater

The terrestrial components of the hydrological cycle include rainwater, surface water, and groundwater. Carbon (C) isotopes allow hydrologists to pinpoint the age of groundwater, track its flow rate, and identify the sources and processes. This research summarizes previous investigations conducted on the isotopes of groundwater and precipitation. The Scopus database contains works from authors from fifty nations, who have conducted research integrating C isotopes in groundwater and precipitation. The review shows that there have been few C isotope investigations on carbon storage and sequestration, as well as on δ13C of precipitation in arid regions. An integrated e-DNA investigation on the process of C isotope fractionation in diverse environments, as well as research on 13C of precipitation in arid regions before and after dust storms, is required to elucidate the relative contributions of biogenic, geogenic, and anthropogenic sources. However, carbon isotope fingerprints that are unique to individual compounds, such as those of fugitive gases, need sophisticated analytical equipment in order to be investigated, limiting this type of study to nations with robust scientific infrastructures and well-trained manpower. The International Atomic Energy Agency (IAEA) has been instrumental in this effort by providing collaborative research and analytical support, resulting in the development of a network for isotope data generation.

Vegetation Greenness Sensitivity to Precipitation and Its Oceanic and Terrestrial Component in Selected Biomes and Ecoregions of the World

In this study, we conducted a global assessment of the sensitivity of vegetation greenness (VGS) to precipitation and to the estimated Lagrangian precipitation time series of oceanic (PLO) and terrestrial (PLT) origin. The study was carried out for terrestrial ecosystems consisting of 9 biomes and 139 ecoregions during the period of 2001–2018. This analysis aimed to diagnose the vegetative response of vegetation to the dominant component of precipitation, which is of particular interest considering the hydroclimatic characteristics of each ecoregion, climate variability, and changes in the origin of precipitation that may occur in the context of climate change. The enhanced vegetation index (EVI) was used as an indicator of vegetation greenness. Without consideration of semi-arid and arid regions and removing the role of temperature and radiation, the results show the maximum VGS to precipitation in boreal high-latitude ecoregions that belong to boreal forest/taiga: temperate grasslands, savannas, and shrublands. Few ecoregions, mainly in the Amazon basin, show a negative sensitivity. We also found that vegetation greenness is generally more sensitive to the component that contributes the least to precipitation and is less stable throughout the year. Therefore, most vegetation greenness in Europe is sensitive to changes in PLT and less to PLO. In contrast, the boreal forest/taiga in northeast Asia and North America is more sensitive to changes in PLO. Finally, in most South American and African ecoregions, where PLT is crucial, the vegetation is more sensitive to PLO, whereas the contrast occurs in the northern and eastern ecoregions of Australia.

The metabolic rate of the biosphere and its components

We assessed the relationship between rates of biological energy utilization and the biomass sustained by that energy utilization, at both the organism and biosphere level. We compiled a dataset comprising >10,000 basal, field, and maximum metabolic rate measurements made on >2,900 individual species, and, in parallel, we quantified rates of energy utilization, on a biomass-normalized basis, by the global biosphere and by its major marine and terrestrial components. The organism-level data, which are dominated by animal species, have a geometric mean among basal metabolic rates of 0.012 W (g C)-1 and an overall range of more than six orders of magnitude. The biosphere as a whole uses energy at an average rate of 0.005 W (g C)-1 but exhibits a five order of magnitude range among its components, from 0.00002 W (g C)-1 for global marine subsurface sediments to 2.3 W (g C)-1 for global marine primary producers. While the average is set primarily by plants and microorganisms, and by the impact of humanity upon those populations, the extremes reflect systems populated almost exclusively by microbes. Mass-normalized energy utilization rates correlate strongly with rates of biomass carbon turnover. Based on our estimates of energy utilization rates in the biosphere, this correlation predicts global mean biomass carbon turnover rates of ~2.3 y-1 for terrestrial soil biota, ~8.5y-1 for marine water column biota, and ~1.0y-1 and ~0.01y-1 for marine sediment biota in the 0 to 0.1m and >0.1m depth intervals, respectively.

Space-Time Causality Analysis of Regional Impacts of ENSO on Terrestrial and Oceanic Precipitation

Future changes are expected in precipitation under climate change, therefore, changes are projected in the oceanic and terrestrial components. However, it remains poorly elucidated how the El Niño–Southern Oscillation (ENSO) can influence these changes. Therefore, we aimed to perform a space-time causality analysis of regional ENSO impacts on terrestrial and oceanic precipitation by using the Granger causality method as a function of eight temporal lags (lags 1–8). The monthly values of total precipitation obtained using the Lagrangian approach and their respective terrestrial (PLT) and oceanic (PLO) components were used. The analysis was performed for the two regions of western North America (WNA) and eastern South America (ESA) with strong ENSO signals. For the WNA region in winter, the maximum Granger causality was observed in the component of oceanic origin for temporal lags 1 and 2 (3 and 6 months), with a predominance of both positive and negative ENSO conditions. For the ESA region, it was verified that the causality of the ENSO index was maximum for PLT. Temporal lags 2–5 (6–15 months) stood out in winter when there was a marked region of the Granger causality over the La Plata Basin. In autumn, for lags 1–4 (3–12 months), the Granger causality values were predominant in the southern and western areas of ESA and showed a tendency to move northward with an increased temporal lag. Finally, it was shown that high correlation values did not imply the causality of the relationship between the ENSO index and precipitation in the two regions.

Stages of palaeoenvironmental evolution, climate and sea level change of the Niger Delta, east Equatorial Atlantic: Novelty from elemental tracers, sedimentary facies and pollen records

This study used the comparative analysis of 3 gravity cores (GCs) obtained from the shallow offshore at ~40 m water depth to reconstruct the morphological evolution of the delta (East Equatorial Atlantic). The focus of this study is on the interpretation of elemental tracers and their justification between these tracers and microfossil data to understand the impact of climate-sea level controls on the evolution of the Niger Delta during the Late Quaternary. Key elemental tracers comprising Ti, Zr, Fe and S were explored to strengthen this concept. High Ti/Zr ratio values down-hole indicate fluvial transport of terrestrial components to the marine setting (20–11.7 ka), whereas high values of Fe/S ratio up-hole provide an extent of inherent marine shale of the Niger Delta (11.7–6.5 ka). In addition, the integrated multiple proxy (mangrove and hinterland pollen, planktonic foraminifera and sedimentary facies) with elemental tracer ratios provided robust and coherent information for delineating the late glacial (MIS2) prograding and interglacial (MIS1) retrograding deltaic transition, respectively. The overall trends of the two elemental tracer ratios (Lower and Mid-upper depths of the GCs) provide a new distinction on the depositional patterns (prograding and retrograding delta) to determine the proximal/upper (clay, silt and very fine sand) and distal offshore/lower shorefaces (coarse-medium sand), and gross palaeoenvironments based on planktonic foraminifera records. These sequential records provide a new clue as evidence of the morphological evolutionary stages (delta plain, delta front and prodelta) of the Niger Delta landscape, gross palaeoenvironments, and vegetation dynamics (pollen data) during two distinct time-bound intervals (20–6.5 ka), which potentially delineate the climate and sea level regime of the coastal offshore.