Dominant Control Research Articles

Research on the Renewal of Multi-Story High-Density Urban Landscape Based on Property Rights Land—A Case Study of the Self-Built Liu Houses in Zherong, Fujian Province

Unlike in Western countries, land ownership in China is overwhelmingly vested in the state, and individuals cannot directly own private lands and build houses. Therefore, developers will contract the land to the government and build it into collective apartments. Against this backdrop, a different kind of multi-story, high-density self-built residential buildings is widespread in small towns along the southeast coast of China. These buildings were built between 1980 and 2000 by residents who acquired land-use rights from the government for compensation. The uniqueness of these buildings is what makes them incompatible with the most mainstream, government-led urban renewal model in China, resulting in a large area of dilapidated and aging areas. Zherong County, Ningde, Fujian Province, is a typical example town, with a large number of such self-built houses, known locally as Liu Houses. In this study, these residential areas were selected as typical research objects of “characteristics of residential small towns”. Combined with the property rights of the sample cases, the methods of diagram and quantitative analysis are used to summarize the causes of the three types of residential areas from the aspects of regional planning, land division, building construction, and renovation. In the early days, the planning of the Liu House was greatly influenced by the residents, and the construction and renovation of the building was led by the residents, which strengthened the diversity of the style. In the middle period, the government had relatively dominant control over the planning of Liu Houses, and supervision was conducted during the construction and renovation process, resulting in a relatively balanced power between residents and the government. In the later period, the houses were built and operated by the developer, and the residents no longer directly participated in the construction and renovation, so the unity of style was strengthened. At the same time, the study finds that, in the process of the formation of the style of the residential area, on the one hand, the property rights directly affect the style through its own physical land attributes, and on the other hand, it becomes the basis of the game between the government, residents, and the county environment through its own property rights, thus indirectly affecting the style. In conclusion, this paper may provide theoretical support and design reference for the renewal of the characteristic features of residential small towns.

A high-strength laminate made of small-diameter plantation wood: Flatwise bending mechanical properties

The aim of this study was to explore the feasibility of manufacturing high-strength laminates from small-diameter plantation wood. A Chinese fir (Cunninghamia lanceolata) plantation comprising trees with a diameter at breast height of less than 30 cm was selected as the material in this study. The flatwise bending mechanical properties of the Chinese fir laminates with both non-finger-jointed (NFJ) and finger-jointed (FJ) were investigated. The results indicated that finger jointing did not affect the bending elastic modulus (MOE) of the laminates, but it could reduce the bending strength index and the coefficient of variation of the bending strength (MOR). Notably, an optimal correlation existed between the MOE and MOR for both NFJ and FJ laminates, indicating that the MOE could serve as the dominant control variable for the machine grading of laminates. The failure mode significantly influenced the bending mechanical properties of both the NFJ and FJ laminates, whose dominant failure modes were fiber failure near the knot and whole fractures of the finger jointing teeth roots, respectively. For both the NFJ and FJ laminates, the overall macroscopic morphology of the high-strength specimen was relatively flat, but the microscopic morphology was uneven owing to fiber pull out, while the low-strength specimen was the opposite. Compared to the traditional visual grading method, the proposed machine grading method could more scientifically and effectively identify the quality, reduce the coefficient of variation of the bending mechanical properties, and significantly improve the strength index of laminates. This study provides basic support for manufacturing high-strength laminates from small-diameter plantation wood.

Primary to post-depositional microbial controls on the stable and clumped isotope record of shoreline sediments at Fayetteville Green Lake.

Lacustrine carbonates are a powerful archive of paleoenvironmental information but are susceptible to post-depositional alteration. Microbial metabolisms can drive such alteration by changing carbonate saturation insitu, thereby driving dissolution or precipitation. The net impact these microbial processes have on the primary δ18O, δ13C, and Δ47 values of lacustrine carbonate is not fully known. We studied the evolution of microbial community structure and the porewater and sediment geochemistry in the upper ~30 cm of sediment from two shoreline sites at Green Lake, Fayetteville, NY over 2 years of seasonal sampling. We linked seasonal and depth-based changes of porewater carbonate chemistry to microbial community composition, insitu carbon cycling (using δ13C values of carbonate, dissolved inorganic carbon (DIC), and organic matter), and dominant allochems and facies. We interpret that microbial processes are a dominant control on carbon cycling within the sediment, affecting porewater DIC, aqueous carbon chemistry, and carbonate carbon and clumped isotope geochemistry. Across all seasons and sites, microbial organic matter remineralization lowers the δ13C of the porewater DIC. Elevated carbonate saturation states in the sediment porewaters (Ω > 3) were attributed to microbes from groups capable of sulfate reduction, which were abundant in the sediment below 5 cm depth. The nearshore carbonate sediments at Green Lake are mainly composed of microbialite intraclasts/oncoids, charophytes, larger calcite crystals, and authigenic micrite-each with a different origin. Authigenic micrite is interpreted to have precipitated insitu from the supersaturated porewaters from microbial metabolism. The stable carbon isotope values (δ13Ccarb) and clumped isotope values (Δ47) of bulk carbonate sediments from the same depth horizons and site varied depending on both the sampling season and the specific location within a site, indicating localized (μm to mm) controls on carbon and clumped isotope values. Our results suggest that biological processes are a dominant control on carbon chemistry within the sedimentary subsurface of the shorelines of Green Lake, from actively forming microbialites to pore space organic matter remineralization and micrite authigenesis. A combination of biological activity, hydrologic balance, and allochem composition of the sediments set the stable carbon, oxygen, and clumped isotope signals preserved by the Green Lake carbonate sediments.

Changing climatic controls on the greenhouse gas balance of thermokarst bogs during succession after permafrost thaw.

Permafrost thaw in northern peatlands causes collapse of permafrost peat plateaus and thermokarst bog development, with potential impacts on atmospheric greenhouse gas exchange. Here, we measured methane and carbon dioxide fluxes over 3 years (including winters) using static chambers along two permafrost thaw transects in northwestern Canada, spanning young (~30 years since thaw), intermediate and mature thermokarst bogs (~200 years since thaw). Young bogs were wetter, warmer and had more hydrophilic vegetation than mature bogs. Methane emissions increased with wetness and soil temperature (40 cm depth) and modelled annual estimates were greatest in the young bog during the warmest year and lowest in the mature bog during the coolest year (21 and 7 g C-CH4 m-2 year-1, respectively). The dominant control on net ecosystem exchange (NEE) in the mature bog (between +20 and -54 g C-CO2 m-2 year-1) was soil temperature (5 cm), causing net CO2 loss due to higher ecosystem respiration (ER) in warmer years. In contrast, wetness controlled NEE in the young and intermediate bogs (between +55 and -95 g C-CO2 m-2 year-1), where years with periodic inundation at the beginning of the growing season caused greater reduction in gross primary productivity than in ER leading to CO2 loss. Winter fluxes (November-April) represented 16% of annual ER and 38% of annual CH4 emissions. Our study found NEE of thermokarst bogs to be close to neutral and rules out large CO2 losses under current conditions. However, high CH4 emissions after thaw caused a positive net radiative forcing effect. While wet conditions favouring high CH4 emissions only persist for the initial young bog period, we showed that continued climate warming with increased ER, and thus, CO2 losses from the mature bog can cause net positive radiative forcing which would last for centuries after permafrost thaw.

Deciphering spatial variability and dominant controls of soil quality under four types of grassland along a southeast-northwest transect in Tibet, southwestern China

Grasslands on the Qinghai-Tibetan Plateau are under threat from ongoing degradation due to natural and anthropogenic perturbations, resulting in widespread decline in the soil quality of grassland. However, the variations, distributions and dominant drivers of soil quality under different grassland types on the plateau have not been studied due to great difficulty in large-scale sampling at high altitudes. We quantitatively assessed soil quality under alpine meadow (AM), alpine steppe (AS), alpine desert steppe (ADS), and alpine desert (AD) along a 900-km southeast-northwest transect in Tibet, southwestern Qinghai-Tibetan Plateau using an improved soil quality index (SQI) approach. Results showed that there was a high spatial variability of SQI across the transect, with an overall increase of SQI from northwest to southeast (P < 0.01). The average SQI of AM (0.51 ± 0.12) and AS (0.47 ± 0.13) was significantly higher than that of ADS (0.33 ± 0.10) and AD (0.30 ± 0.10) (P < 0.05). Random forest analysis demonstrated that soil property, vegetation factors, environmental conditions and human activity exhibited a decreasing order of the relative importance on SQI. Interactions of soil property and vegetation factors significantly influenced SQI as indicated by the structural equation modeling (P < 0.05). Pedotransfer function (PTF) was applied to adequately predict the soil quality of grassland in Tibet (RMSE = 0.087, R2 = 0.647, P < 0.01), but an extrapolation of the established PTF for estimating grassland soil quality in another alpine region in northeastern Qinghai-Tibetan Plateau requires the nonlinear least squares correction to improve the prediction accuracy. This study unravelled the spatial variability and dominant controls of the soil quality of grassland in Tibet and established a high-precision forecasting model of SQI by considering the grassland type, providing a basis for accurately predicting and sustainably managing grassland soil quality in the alpine region. Reducing grazing intensity and vegetation restoration are needed to improve the soil quality of grassland on the Qinghai-Tibetan Plateau.

The Fate of Bars in Braided Rivers

Ancient river deposits are important archives of past landscape conditions on planetary surfaces. On Earth, they host valuable groundwater, energy resources, and carbon-storage potential. Reconstructing details of paleochannel forms and movements refines our understanding of the controls on river behavior under different climate, landcover, and tectonic conditions, and improves predictions and models of subsurface reservoirs. While studies have shown detailed connections between channel kinematics and bar-deposit architecture in meandering river systems, similar connections between braided river movements and preserved braided river deposits have not been established. Here we explore the potential for connecting braided river deposits to paleochannel movements, form, and flow conditions, and we evaluate the controls on bar preservation using synthetic stratigraphy generated with a numerical morphodynamic model. We investigate how attributes of channel morphodynamics, like channel widening or braiding intensity, impact bar deposits’ preservation, scale, geometry, and architecture. We then assess how the scale, preservation, and facies composition of bar deposits reflect formative flow conditions of the channel. Our results demonstrate that no diagnostic signature of braided channel morphodynamics is recorded in bar-deposit geometry, facies, or preservation patterns. Rather, the unique local history of thread movements combines stochastically to preserve or rework bar deposits, and the timing of channel avulsion is the dominant control on bar preservation. Our results also show that representative paleochannel flow conditions will likely be accurately reflected in aggregate observations of braid bar deposits within channel-belt sandbodies at a regional or member/formation scale. These results demonstrate the need for broad sampling and statistical approaches to subsurface prediction and paleo-flow reconstruction in ancient, braided river deposits.

Enhanced Removal of River‐Borne Nitrate in Bioturbated Hyporheic Zone

AbstractThe influence of bioturbation induced by bottom‐dwelling macrozoobenthos on nitrogen dynamics in lotic stream sediments remains unclear. In this work, we advance the understanding of faunal bioturbation in lotic environments by developing a fully‐coupled flow and multicomponent reactive transport model and investigate the influence of sediment reworking and burrow ventilation processes on nitrogenous transformations. The model results indicate that sediment reworking and burrow ventilation significantly increase nitrate (NO3−) influx, penetration depth, and reaction rates in the streambed. Denitrification rates were observed up to three times higher in beds with U‐shaped burrows compared to flatbeds. The ratio of mound height to stream water depth ratio (h/H0) is a dominant control on determining the relative importance of the sediment reworking and burrow ventilation processes in modulating nitrogenous reactions. A power‐law scaling framework is ultimately proposed to predict NO3− removal efficiency based on the Damköhler number in bioturbated lotic streambeds.

Dehydration of goethite during vacuum step-heating and implications for he retentivity characterization

Uncertainty exists over what environmental conditions and mineralogical/chemical properties are required to ensure retention of helium such that (UTh)/He dates record the time of goethite crystallization. We undertook vacuum step heating experiments to determine He diffusion parameters for extrapolation to Earth surface conditions on 10 goethite specimens in which we had created a uniform distribution of 3He. Arrhenius plots of apparent diffusion coefficients on all samples follow the same pattern. At temperatures <200 °C the data define arrays consistent with progressive degassing of increasingly large crystallites. However, above 200 °C the computed diffusivities increase dramatically until about 80% of the helium is extracted, after which they suddenly decline. The sudden increase in diffusivity at 200 °C coincides with the onset of dehydration of the goethite structure, a process which continues throughout the remainder of the step heat. There is a strong correlation between evolved water and 3He amounts. These observations likely reflect previously reported processes of formation, growth, and coalescence of pores as the phase transition to hematite proceeds. While significantly higher dehydration temperatures of ∼270 °C are observed using techniques such as thermogravimetric analysis in air, the long step durations, and vacuum conditions of our experiments destabilize goethite. Orders of magnitude differences in the computed diffusivities among our samples may reflect crystallite-size-distribution control on dehydration kinetics, and the qualitative size distributions we infer from the step heats are consistent with SEM observations of crystallite lengths. Vacuum step-heating experiments in which goethite is decomposing cannot be used to determine He diffusion behavior in nature, but the inferred crystallite size distribution provides some useful indirect evidence. A strong relationship exists between metrics of the crystallite size distribution from step heating results and the degree of He retention in nature inferred from the 4He/3He method. This observation provides evidence supporting the validity of the 4He/3He technique for estimating retention, and further suggests that the dominant control on He retention in nature is the crystallite size distribution. Experiments under hydrothermal conditions in which goethite remains stable may be an alternative approach to address the question of He diffusion behavior in nature.

Seasonal variations in lithium and magnesium isotopic composition of the Nujiang River water at the Daojieba Hydrological Station: Implications for chemical weathering

The response of chemical weathering to climate could be examined in a way by investigating seasonal changes in river geochemistry. Here, we determined the major elements, δ13C of DIC, 87Sr/86Sr, δ7Li, and δ26Mg of monthly time-series water samples at the Daojieba Hydrological Station in lower reach of the Nujiang River over a hydrological year. During high-flow seasons, the dissolved 87Sr/86Sr, δ7Li, and δ26Mg exhibit comparatively high values. 87Sr/86Sr ratio, together with δ13C of DIC, Si/Ca ratio, and pH value of river water, indicate an enhanced silicate weathering contribution to river dissolved load, and river δ7Li is impacted by secondary mineral formation-related fractionation during these periods. Similar to the 87Sr/86Sr ratio, δ26Mg of river water is indicative of a dominant source control. The positive relationship between Mg/Na ratio and δ26Mg value suggests that the prior weathering of Mg-rich silicate minerals could be important for elevated δ26Mg and Mg/Na molar ratio during high-flow seasons, while the Mg isotope fractionation signal can be seen when runoff increases dramatically. During low-flow seasons, river 87Sr/86Sr and δ26Mg values evolve to a carbonate weathering signal, whereas river δ7Li reflects a more congruent silicate weathering, and these changes point to the obvious influence of geothermal water in these periods. The covariations of δ7Li, δ26Mg, and discharge are observed. Changes in runoff can significantly impact the isotopic composition of Li and Mg by changing the hydrological flow path, in which dominant reactions of mineral dissolution and secondary mineral formation vary. This study highlights the hydrological control on Li and Mg isotopic compositions of the Nujiang River water, which could be considered the dominant control of monsoon climate on weathering processes in high-relief river basins at a short-term scale.

Colonial Sustainability: Tracing the Sustainability Industry’s Ecocidal Lineage from the Doctrine of Discovery

The concept of “sustainable development” fuelling today’s sustainability industry may be traced back to the turn of the 14th century. The Holy Roman Empire’s imperialistic expansions into Africa and the Canary Islands eventually morphed into a burgeoning capitalist European colonial project, which then sought to undo the very environmental harms it had wrought through colonial extraction from further colonial domination and social control. Post-World War II “peace” efforts birthed supranational entities that continue to impose white supremacist epistemological systems, frames, and standards on the neocolonised Global South. These impositions led to the creation of the contemporary sustainability industry, enabling the obfuscation of Global North expansionism through the application of white supremacist, Western-centric sustainability rhetoric. The cultural evolution of “sustainability” moves steadily apace as decolonial counternarratives struggle to materialise amid active silencing and stamping out by the mechanisms of coloniality.

New strain configuration of convergence in the Arabia-Eurasia collisional zone: A comprehensive analysis of large shear zones inferred from geodetic and seismic observations

A new strain configuration is presented concerning the ongoing convergence deformation field in the Turkish-Iranian High Plateau (TIHP), E Anatolia-NW Iran. The strain configuration is derived from the contribution of geodetic strain-rate fields using GPS velocity data to reveal new constraints not documented previously in the region. This provides good evidence for novel “highland shear strain zones” by analysis of the combination of interpolated GPS velocity fields and seismological observations with maximum principal strain axes. Both the strain-rate fields and rotational elements of the estimated geodetic deformation exhibit juxtaposed, patchy strain rate partitioning in E Anatolia-NW Iran. These comprise both compressional strain lobes combined with local extensional areas and large shear strain fields in the core of the collision where the rotation rate fields present an unexpected propagation zone of continuous, counterclockwise rotation towards the W. The main results define approximately N-S- and W-E-trending, large, continuous, diagonal shear strain patterns with high total strain rate and maximum shear strain rate, consistent with right-lateral strike-slip and normal focal mechanisms. These are the Longitudinal Shear Zone (LSZ) extending from S to N and dividing the TIHP into the E Anatolia and NW Iran blocks, and the right-lateral Transcurrent Shear Zone (TSZ) extending from E (NW Iran) to W (E Anatolia). These differential movements of the inconsistent LSZ and TSZ shape both the highly buoyant plateau topography and the area, which undergoes migration to the W with respect to stable Eurasia by means of plateau push. Geodetic deformation compatible with fault focal data indicates that the LSZ and TSZ, in the framework of thermal and mechanical changes in the structure of the lithospheric thickness beneath the TIHP, are invaded and shaped by flowing mantle material that triggers and drives lateral escape of convergent crustal blocks, and configures the convergence with a shear-dominated deformation regime. The shear regime is primarily driven by NE- and NW-directed mantle flow fields and associated buoyancy forces due to slab fragmentation and tears in the region, exerting dominant control over the differential evolution of the LSZ and TSZ patterns. The new strain configuration for this convergence illuminates “the highland tectonics of large shear zones” resulting from slab thinning or its absence, and challenges conventional tectonic strain models in the TIHP.

Two-stage many-objective evolutionary algorithm: enhanced dominance relations and control mechanisms for separated balance

Although the multiobjective evolutionary algorithms (MOEAs) have been proved to bring promising prospects for solving multiobjective optimization problems (MOPs), the performance of the algorithm deteriorates sharply in high-dimensional objective space due to the weak selection pressure and the unregulated balance, which is caused by the increase of objective space dimension. Some current MOEAs with two-stage strategy (TS) strive to address above issues by dividing the evolutionary process into two independent stages, in which convergence and diversity are handled separately within successive generations of different stages. However, TS-MOEAs have some weaknesses, such as sensitivity to stage division, and incomplete separation of convergence and diversity. In this paper, TS/KW-MaOEA is proposed for solving many-objective optimization problems (MaOPs), which keeps TS as the central and equips a perfect control mechanism for separated balance. More specifically, TS/KW-MaOEA can automatically adjust the balance trend and provide appropriate selection pressure for MaOPs according to the Kondratiev wave (KW) search model and the objective space dimension. To verify the effectiveness of the proposed algorithm, a series of experiments are carried out against seven state-of-the-art many-objective optimization algorithms on 15 benchmark problems with up to 30 objectives. Experimental results indicate that the proposed algorithm is highly competitive against peer competitors.

Do lower limb kinetic and kinematic differences in drop jump landings persist when players have returned to sport following knee ligamentous injuries?

Knee injuries (KI) are identified as one of the most burdensome lower limb injuries in football with long and complicated rehabilitation and high re-injury risk. Current research often describes technique deficits being present upon RTS, often being a result of poor return to sport (RTS) testing procedures. More recently, research has advocated the use of single leg vertical jump assessments, due to the specificity of the movement to injury mechanisms and the ability to consider different phases of the task to inform practitioners of joint contributions to the propulsion and landing phases. The aim of this research is to identify whether these functional deficits exist 12-24 months post RTS authorisation, to help inform future RTS in applied practice. Twenty-four semi-professional male footballers (mean ± SD: age 25 ± 4 years; stature 182 ± 7 cm; body mass 80 ± 8 kg) were recruited into a previously injured and a control group. Participants completed 5 repetitions of single leg drop jump (SLDJ). Jump height, ground contact time, reactive strength index, peak moments, angles and power contributions for the hip, knee and ankle were measured using Qualisys Track Manager then exported to Visual 3D. This study was approved by the Edge Hill University Ethics Committee. No significant findings were identified for landing one however, during the propulsion phase there was a difference between groups (P = 0.026, d=1.14) for knee flexion at take-off. Most differences were identified during landing two bilaterally in both groups. Within the injured group, differences were identified for peak hip (P = 0.011, d = 0.028) and knee powers (P &lt; 0.001, d = 1.269), hip (P &lt; 0.001, d = 1.924) and knee power contribution % (P &lt; 0.001, d = 1.269). No differences were identified for the performance measures or through performing statistical parametric mapping for hip and knee powers for all three phases. Joint coupling analysis was conducted for the total ground contact time amalgamating the landing and propulsion phase, this was analysed as Hip-Knee, Hip-Ankle and Knee-Ankle, with significant findings in Hip-Knee and Hip-ankle. Both groups elicited bilateral differences however, no differences between the injured limb and dominant control limb were identified. To better apply this form of analysis to RTS testing, functional movements such should be undertaken when athletes are injury free to provide baseline measurements to refer to if undertaking rehabilitation from KI. Likewise, the current study identified that joint contributions could be identified in a more applied setting using the range of motion data from each joint.

The magma plumbing system of the Northern Carnarvon Basin, offshore Australia: multiscale controls on basin-wide magma emplacement, and implications for petroleum exploration

Abstract The Northern Carnarvon Basin (NCB) located on Australia's North West Shelf hosts an extensive (∼40 000 km 2 ) intrusive igneous complex related to Mesozoic rifting and break-up. Using an extensive suite of modern 3D seismic reflection surveys, we have mapped this intrusive system across the NCB. We identify three predominant intrusion morphologies: stacked sheets of large interconnected sill intrusions (up to ∼170 km long) and smaller (8–30 km long) isolated, strata concordant intrusions, which often interact with normal faults emplaced into deltaic sedimentary rocks, and variably sized (10–40 km long) saucer-shaped intrusions emplaced into marine shales, spread across seven zones (geographically constrained groups of intrusions of a specific morphology). We consider the zones’ margin-parallel orientation, suggesting control by subcrustal extensional processes during rifting, and the variation in intrusion morphology between these zones, suggesting a dominant control by host rock mechanical properties. We integrate previous work with our observations, constraining emplacement to between the Kimmeridgian and Valanginian, coinciding with key phases of margin evolution. Finally, we assess the impact of this intrusive complex on local petroleum systems. There is likely little to no adverse impact on source rock maturation or reservoir contamination by CO 2 , but there is a spatial dissociation between the location of groups of intrusions and the gas fields, particularly in the Exmouth Plateau. This suggests that migrating hydrocarbons may be blocked, baffled and/or redirected by emplaced igneous rocks.

Predicting the temporal-spatial distribution of chlorophyll-a in the Yellow River estuary using explainable machine learning

The water quality in estuaries is influenced by both physical and biochemical processes, making it difficult to identify and quantify the main controlling factors of chlorophyll-a (Chl-a) concentration. This study introduces an interpretable machine learning approach to identify and quantify the dominant control factors determining Chl-a concentration in the Yellow River Estuary (YRE). The model utilizes in situ data and MODIS data in the Yellow River Estuary, incorporating five key variables: salinity, water depth, turbidity, dissolved inorganic nitrogen (DIN), and soluble reactive phosphorus (SRP). Three types of inputs are used to predict Chl-a, including physical, biogeochemical, and physical-biogeochemical factors. The model further uses feature importance ranking and partial dependence plot to identify and quantify key control factors. The results reveal that (1) Chl-a variation is influenced by multiple factors, especially salinity and turbidity; (2) Chl-a concentration is inhibited when salinity is below 26, turbidity is lower than 16 NTU and above 30 NTU, DIN is lower than 0.314 mg/L and SRP is below 0.01 mg/L; (3) riverine inputs change turbidity and salinity in the Yellow River Estuary and Laizhou Bay, in response to temporal-spatial distributions of phytoplankton. This research can provide a valuable reference for water quality management in the Yellow River Estuary.

Factors controlling spatiotemporal variability of soil carbon accumulation and stock estimates in a tidal salt marsh

Abstract. Tidal salt marshes are important contributors to soil carbon (C) stocks despite their relatively small land surface area. Although it is well understood that salt marshes have soil C burial rates orders of magnitude greater than those of terrestrial ecosystems, there is a wide range in accrual rates among spatially distributed marshes. In addition, wide ranges in C accrual rates also exist within a single marsh ecosystem. Tidal marshes often contain multiple species of cordgrass due to variations in hydrology and soil biogeochemistry caused by microtopography and distance from tidal creeks, creating distinct subsites. Our overarching objective was to observe how soil C concentration and dissolved organic carbon (DOC) vary across four plant phenophases and across three subsites categorized by unique vegetation and hydrology. We also investigated the dominant biogeochemical controls on the spatiotemporal variability of soil C and DOC concentrations. We hypothesized that subsite biogeochemistry drives spatial heterogeneity in soil C concentration, and this causes variability in total soil C and DOC concentrations at the marsh scale. In addition, we hypothesized that soil C concentration and porewater biogeochemistry vary temporally across the four plant phenophases (i.e., senescence, dormancy, green-up, maturity). To test these interrelated hypotheses, we quantified soil C and DOC concentrations in 12 cm sections of soil cores (0–48 cm depth) across time (i.e., phenophase) and space (i.e., subsite), alongside several other porewater biogeochemical variables. Soil C concentration varied significantly (p &lt; 0.05) among the three subsites and was significantly greater during plant dormancy. Soil S, porewater sulfide, redox potential, and depth predicted 44 % of the variability in soil C concentration. There were also significant spatial differences in the optical characterization properties of DOC across subsites. Our results show that soil C varied spatially across a marsh ecosystem by up to 63 % and across plant phenophase by 26 %, causing variability in soil C accrual rates and stocks depending on where and when samples are taken. This shows that hydrology, biogeochemistry, and plant phenology are major controls on salt marsh C content. It is critical to consider spatiotemporal heterogeneity in soil C concentration and porewater biogeochemistry to account for these sources of uncertainty in C stock estimates. We recommend that multiple locations and sampling time points are sampled when conducting blue C assessments to account for ecosystem-scale variability.

Precessional forcing of biogeochemical and nutrient cycling in the tropical western Pacific during the late Pleistocene

Unravelling the biogenic material export production and its relationship to surface ocean nutrient conditions, along with their external forcing, will provide insights into the ocean carbon biogeochemical cycle. In this study, we present data on coccolith particulate inorganic carbon (PIC) export production, coccolith carbon isotopic vital effects, and planktonic foraminifer cadmium to calcium ratio in the tropical western Pacific over the past 250 kiloyears (kyr). These proxies indicate the strength of the coccolith-based carbonate counter pump or coccolithophore productivity, and phosphate concentration in the surface ocean. Our results show that low phosphate concentration correlates with enhanced coccolith-based carbonate counter pump in the precessional band (a cyclicity of 19–23 kyr). Additionally, low phosphate concentration, which indicates high degree of phosphorus utilization, is coupled with enhanced nitrogen fixation, as shown by a nitrogen isotope record in the tropical western Pacific. Greater precipitation in Papua New Guinea (PNG) can occur during local insolation maxima, suggesting a dominant control of precession. This will in turn drive the biogeochemical and nutrient cycling in the tropical western Pacific. We propose that higher amounts of the PNG riverine input caused by greater precipitation can provide additional nutrients and trace element iron (Fe) for phytoplankton. An increased bioavailable Fe in the surface ocean can promote the growth of nitrogen-fixing diazotrophs, which results in a high degree of phosphorus utilization and relieves a potential nitrogen limitation. This may ultimately lead to increased biological productivity, e.g., the coccolith PIC.

Future projection of tropical cyclone genesis in the Western North pacific using high-resolution GCMs and genesis potential indices

The study employed high-resolution atmospheric general circulation models (AGCM) to simulate tropical cyclones (TCs) and evaluated two TC genesis potential indices in reflecting projected TC changes in the western North Pacific (WNP) under a warming scenario. Both indices accurately represented the seasonal variation of TC genesis frequency (TCGF) and its spatial distribution in historical simulations and observation data. The widely-used TC genesis potential index (χGPI) projected a significant increase in TCGF in response to a warmer ocean surface. However, this projection conflicted with the significant reduction in the model projection due to the dominant control of SST on the χGPI. Higher SST in remote ocean basins often over dominated the destabilization effect of in-situ warmer SST and caused more stable atmospheric conditions in the WNP, resulting in fewer TC occurrences. By contrast, the revised index (χMqGPI), which considers gross moisture condensation, projected a TCGF decrease that more accurately reflected the decreasing trend of TCGF in the warming simulations by AGCM, although the degree of reduction was smaller than that derived directly from TC detection scheme. The results suggest the plausibility of using χMqGPI, based on the results of multimodel coarse-resolution CMIP6 climate models, to project future changes in TCGF in the WNP.

Lithology and subsurface structures related to gold mineralisation in the Kibati prospect, Mozambique belt in eastern Tanzania, with implications for gold exploration

This paper provides an insight into the structures, lithologies, and potential zones and their relationships to gold mineralisation that were investigated to decipher the controls of gold mineralisation at the Kibati Gold Prospect within the Mozambique Belt. Although the Kibati area is located within the gold mineralised zone, lithology and subsurface geological structures associated with gold mineralisation are not well studied. The available high-resolution aeromagnetic data have not yet also been analysed and interpreted to derive geological features that are useful in mineral exploration. The investigation of the structures and lithologies was accomplished through integrated interpretation of high-resolution aeromagnetic data, ground magnetic data, geological mapping, and rock sampling. Aeromagnetic and ground magnetic results reveal the presence of two structural systems, which were previously not identified that trend in NW–SE and NE–SW, with the NW–SE being the dominant control of gold mineralisation. The subsurface structure with NW–SE trending controls the mineralised fluids as a consequence of gold mineralisation in the surface lithologies. Petrography and geological mapping show that granitic gneiss, garnet-biotite quartzo-feldspathic gneiss, dolerite, and amphibolite are the main exposed outcrops where the first two identified types of gneisses, based on their protolith, were previously not specified. Based on the gold assay results, which are persistent and collinear to the structural trend of NW–SE picked out by magnetic data, two (2) potential blocks (A and B) were identified. The trend of the structure in blocks A and B when overlaid with gold anomalies indicates that most of the gold concentrations are located in block B and the highest value of gold concentrations is located in block A where gold values range from 10.19 to 19.680 g/t in block A and 0.0623 to 4.419 g/t in block B. The difference in gold values between blocks A and B is due to the variation in the degree of alteration. The integration of the results indicates that the gold mineralisation in the Kibati area is structurally controlled and concentrated in shear zones. The findings therefore, indicate that the Mozambique Belt is potential for gold mineralisation and provide a warrant for future plan for gold exploration.

Manganese exposure from spring and well waters in the Shenandoah Valley: interplay of aquifer lithology, soil composition, and redox conditions

Manganese (Mn) is of particular concern in groundwater, as low-level chronic exposure to aqueous Mn concentrations in drinking water can result in a variety of health and neurodevelopmental effects. Much of the global population relies on drinking water sourced from karst aquifers. Thus, we seek to assess the relative risk of Mn contamination in karst by investigating the Shenandoah Valley, VA region, as it is underlain by both karst and non-karst aquifers and much of the population relies on water wells and spring water. Water and soil samples were collected throughout the Shenandoah Valley, to supplement pre-existing well water and spring data from the National Water Information System and the Virginia Household Water Quality Program, totaling 1815 wells and 119 springs. Soils were analyzed using X-ray fluorescence and Mn K-Edge X-ray absorption near-edge structure spectroscopy. Factors such as soil type, soil geochemistry, and aquifer lithology were linked with each location to determine if correlations exist with aqueous Mn concentrations. Analyzing the distribution of Mn in drinking water sources suggests that water wells and springs within karst aquifers are preferable with respect to chronic Mn exposure, with < 4.9% of wells and springs in dolostone and limestone aquifers exceeding 100 ppb Mn, while sandstone and shale aquifers have a heightened risk, with > 20% of wells exceeding 100 ppb Mn. The geochemistry of associated soils and spatial relationships to various hydrologic and geologic features indicates that water interactions with aquifer lithology and soils contribute to aqueous Mn concentrations. Relationships between aqueous Mn in spring waters and Mn in soils indicate that increasing aqueous Mn is correlated with decreasing soil Mn(IV). These results point to redox conditions exerting a dominant control on Mn in this region.