Exchange Transport Research Articles

Molecular dynamics simulation of hydration and free energy of ions in nanochannels of polyelectrolyte threaded metal organic framework and the impacts on selective ion transport

Hierarchical porous materials constructed by threading polyelectrolyte in metal organic framework (MOF) display superior ion exchange behavior. To understand the ion exchange and ion transport mechanism, we conduct molecular dynamics simulations of ions inside the nanochannel of a MOF that is threaded with a polyelectrolyte (polyelectrolyte∼MOF), specifically the poly(sodium vinyl sulfonated-co-acrylic acid)∼MIL-53(Al). We compute the free energy change and hydration number for four representative ions, Na+, K+, Cl− and Mg2+ in the absence and presence of poly(sodium vinyl sulfonated-co-acrylic acid) in a channel of MIL-53(Al). The free energy barrier to ion entry, and the interaction between ion and polyelectrolyte help to understand the selectivity in ion transport. The negative charge of polyelectrolyte can exert a repulsion to anion and attract cation in the neighboring channel of MOF, as indicated by the lower energy valley for monovalent cations Na+ and K+, and higher energy barrier for Cl−. The second hydration shell explains size-selective prohibition of the transport of divalent Mg2+ in the nanochannel of MIL-53(Al). Our results demonstrate that the ion selectivity is attributed to the synergistic effect of charge and size-exclusion of the polyelectrolyte∼MOF structure.

Long-term evolution of ocean eddy activity in a warming world

Mesoscale ocean eddies, an important element of the climate system, impact ocean circulation, heat uptake, gas exchange, carbon sequestration and nutrient transport. Much of what is known about ongoing changes in ocean eddy activity is based on satellite altimetry; however, the length of the altimetry record is limited, making it difficult to distinguish anthropogenic change from natural variability. Using a climate model that exploits a variable-resolution unstructured mesh in the ocean component to enhance grid resolution in eddy-rich regions, we investigate the long-term response of ocean eddy activity to anthropogenic climate change. Eddy kinetic energy is projected to shift poleward in most eddy-rich regions, to intensify in the Kuroshio Current, Brazil and Malvinas currents and Antarctic Circumpolar Current and to decrease in the Gulf Stream. Modelled changes are linked to elements of the broader climate including Atlantic meridional overturning circulation decline, intensifying Agulhas leakage and shifting Southern Hemisphere westerlies.

A metabolic, phylogenomic and environmental atlas of diatom plastid transporters from the model species Phaeodactylum.

Diatoms are an important group of algae, contributing nearly 40% of total marine photosynthetic activity. However, the specific molecular agents and transporters underpinning the metabolic efficiency of the diatom plastid remain to be revealed. We performed in silico analyses of 70 predicted plastid transporters identified by genome-wide searches of Phaeodactylum tricornutum. We considered similarity with Arabidopsis thaliana plastid transporters, transcriptional co-regulation with genes encoding core plastid metabolic pathways and with genes encoded in the mitochondrial genomes, inferred evolutionary histories using single-gene phylogeny, and environmental expression trends using Tara Oceans meta-transcriptomics and meta-genomes data. Our data reveal diatoms conserve some of the ion, nucleotide and sugar plastid transporters associated with plants, such as non-specific triose phosphate transporters implicated in the transport of phosphorylated sugars, NTP/NDP and cation exchange transporters. However, our data also highlight the presence of diatom-specific transporter functions, such as carbon and amino acid transporters implicated in intricate plastid-mitochondria crosstalk events. These confirm previous observations that substrate non-specific triose phosphate transporters (TPT) may exist as principal transporters of phosphorylated sugars into and out of the diatom plastid, alongside suggesting probable agents of NTP exchange. Carbon and amino acid transport may be related to intricate metabolic plastid-mitochondria crosstalk. We additionally provide evidence from environmental meta-transcriptomic/meta- genomic data that plastid transporters may underpin diatom sensitivity to ocean warming, and identify a diatom plastid transporter (J43171) whose expression may be positively correlated with temperature.

The Physiological Function and Potential Role of the Ubiquitous Na+/H+ Exchanger Isoform 8 (NHE8): An Overview Data.

The Na+/H+ exchanger transporters (NHE) play an important role in various biologic processes including Na+ absorption, intracellular pH homeostasis, cell volume regulation, proliferation, and apoptosis. The wide expression pattern and cellular localization of NHEs make these proteins pivotal players in virtually all human tissues and organs. In addition, recent studies suggest that NHEs may be one of the primeval transport protein forms in the history of life. Among the different isoforms, the most well-characterized NHEs are the Na+/H+ exchanger isoform 1 (NHE1) and Na+/H+ exchanger isoform 3 (NHE3). However, Na+/H+ exchanger isoform 8 (NHE8) has been receiving attention based on its recent discoveries in the gastrointestinal tract. In this review, we will discuss what is known about the physiological function and potential role of NHE8 in the main organ systems, including useful overviews that could inspire new studies on this multifaceted protein.

Coupled modeling of peatlands carbon cycle and carbon dioxide emission from their peat deposits

COmplex Model of BOg LAndscapes (COMBOLA) is a set of dynamic models of carbon and nitrogen turnover, net ecosystem exchange, water balance, heat and water transport, generation and transfer of CO2 and CH4 in a peat deposit on a number of time scales. Combined modeling of carbon turnover and carbon dioxide emission from peat deposits on an annual time scale is carried out as part of COMBOLA for several bog landscapes in Western-Siberian south taiga. One-dimensional vertical reaction-diffusion model for carbon dioxide emission from peat deposit is combined with compartment carbon cycle model allowing estimate both bog type vegetation changes and greenhouse gases balance under probable climate change or perturbations initiated by human activities. Water table level (WTL) separating aerobic peat layer from the anaerobic one is calculated by means of the whole peat layer depth and its water balance relations. Minimal statistical information is used for calibrating temperature dependencies together with coefficients of heat and water transfer equations. The stationary states of carbon cycle are accompanied by steady average profiles of carbon dioxide concentration and can loose stability under human or climatic perturbations. The model dynamics is simulated with several climatic projections of the IPSL atmospheric circulation model for 21st century with anthropogenic scenarios RCP-2.6 and RCP-8.5.

Reduction of bundle sheath size boosts cyclic electron flow in C4Setaria viridis acclimated to low light

SUMMARYWhen C4 leaves are exposed to low light, the CO2 concentration in the bundle sheath (BS) cells decreases, causing an increase in photorespiration relative to assimilation, and a consequent reduction in biochemical efficiency. These effects can be mitigated by complex acclimation syndromes, which are of primary importance for crop productivity but are not well studied. We unveil an acclimation strategy involving the coordination of electron transport processes. First, we characterize the anatomy, gas exchange and electron transport of C4 Setaria viridis grown under low light. Through a purposely developed biochemical model, we resolve the photon fluxes and reaction rates to explain how the concerted acclimation strategies sustain photosynthetic efficiency. Our results show that a smaller BS in low‐light‐grown plants limited leakiness (the ratio of CO2 leak rate out of the BS over the rate of supply via C4 acid decarboxylation) but sacrificed light harvesting and ATP production. To counter ATP shortage and maintain high assimilation rates, plants facilitated light penetration through the mesophyll and upregulated cyclic electron flow in the BS. This shade tolerance mechanism, based on the optimization of light reactions, is possibly more efficient than the known mechanisms involving the rearrangement of carbon metabolism, and could potentially lead to innovative strategies for crop improvement.

Fe2O3-modified graphene oxide mitigates nanoplastic toxicity via regulating gas exchange, photosynthesis, and antioxidant system in Triticum aestivum

The ever-increasing plastic pollution in soil and water resources raises concerns about its effects on terrestrial plants and agroecosystems. Although there are many reports about the contamination with nanoplastics on plants, the presence of magneto-assisted nanomaterials enabling the removal of their adverse impacts still remains unclear. Therefore, the purpose of the current study is to evaluate the potential of nanomaterial Fe2O3-modified graphene oxide (FGO, 50–250 mg L−1) to eliminate the adverse effects of nanoplastics in plants. Wheat plants exposed to polystyrene nanoplastics concentrations (PS, 10, 50 and 100 mg L−1) showed decreased growth, water content and loss of photosynthetic efficiency. PS toxicity negatively altered gas exchange, antenna structure and electron transport in photosystems. Although the antioxidant system was partially activated (only superoxide dismutase (SOD), NADPH oxidase (NOX) and glutathione reductase (GR)) in plants treated with PS, it failed to prevent PS-triggered oxidative damage, as showing lipid peroxidation and hydrogen peroxide (H2O2) levels. FGOs eliminated the adverse impacts of PS pollution on growth, water status, gas exchange and oxidative stress markers. In addition, FGOs preserve the biochemical reactions of photosynthesis by actively increasing chlorophyll fluorescence parameters in the stressed-wheat leaves. The activities of all enzymatic antioxidants increased, and the H2O2 and TBARS contents decreased. GSH-mediated detoxifying antioxidants such as glutathione S-transferase (GST) and glutathione peroxidase (GPX) were stimulated by FGOs against PS pollution. FGOs also triggered the enzymes and non-enzymes related to the Asada-Halliwell cycle and protected the regeneration of ascorbate (AsA) and glutathione (GSH). Our findings indicated that FGO had the potential to mitigate nanoplastic-induced damage in wheat by regulating water relations, protecting photosynthesis reactions and providing efficient ROS scavenging with high antioxidant capacity. This is the first report on removing PS-induced damage by FGO applications in wheat leaves.

Preparation and comparative evaluation of PVC/PbO and PVC/PbO/graphite based conductive nanocomposites

Abstract Two series, A and B, of PVC based nanocomposite polymer membranes (nCPMs) were prepared using PbO only and PbO/graphite mixture as a filler by solution casting method. Seven samples with varying compositions (5–35%) of filler particles were prepared for each series and were compared by thickness measurements, porosity, water uptake, swelling degree, ionic conductivity, ion exchange capacity (IEC), membrane potential and transport number. The maximum values for these characteristics were observed as 0.402 mm, 0.77, 141.3%, 0.11, 0.0033 Scm−1, 8.6 milli-eq.g−1, 0.19 V and 0.01391 for series-A composites whereas that of 0.367 mm, 0.83, 63.4%, 0.019, 0.00981 Scm−1, 5.21 milli-eq.g−1, 0.13 V and 0.0108 for series-B nCPMs respectively. The SEM images of membranes showed greater voids produced in the series-B compared to series-A composites. The maximum Ionic conductivity, IEC, membrane potential and transport number were observed for membrane with 25% PbO/graphite, 20% PbO and 35% PbO particles respectively.

Anion Exchange Membranes for Alkaline Polymer Electrolyte Fuel Cells-A Concise Review.

Solid anion exchange membrane (AEM) electrolytes are an essential commodity considering their importance as separators in alkaline polymer electrolyte fuel cells (APEFC). Mechanical and thermal stability are distinguished by polymer matrix characteristics, whereas anion exchange capacity, transport number, and conductivities are governed by the anionic group. The physico-chemical stability is regulated mostly by the polymer matrix and, to a lesser extent, the cationic head framework. The quaternary ammonium (QA), phosphonium, guanidinium, benzimidazolium, pyrrolidinium, and spirocyclic cation-based AEMs are widely studied in the literature. In addition, ion solvating blends, hybrids, and interpenetrating networks still hold prominence in terms of membrane stability. To realize and enhance the performance of an alkaline polymer electrolyte fuel cell (APEFC), it is also necessary to understand the transport processes for the hydroxyl (OH−) ion in anion exchange membranes. In the present review, the radiation grafting of the monomer and chemical modification to introduce cationic charges/moiety are emphasized. In follow-up, the recent advances in the synthesis of anion exchange membranes from poly(phenylene oxide) via chloromethylation and quaternization, and from aliphatic polymers such as poly(vinyl alcohol) and chitosan via direct quaternization are highlighted. Overall, this review concisely provides an in-depth analysis of recent advances in anion exchange membrane (AEM) and its viability in APEFC.

Substrates of the Human Brain Proton-Organic Cation Antiporter and Comparison with Organic Cation Transporter 1 Activities.

Many organic cations (OCs) may be transported through membranes by a genetically still uncharacterized proton-organic cation (H + OC) antiporter. Here, we characterized an extended substrate spectrum of this antiporter. We studied the uptake of 72 drugs in hCMEC/D3 cells as a model of the human blood–brain barrier. All 72 drugs were tested with exchange transport assays and the transport of 26 of the drugs was studied in more detail concerning concentration-dependent uptake and susceptibility to specific inhibitors. According to exchange transport assays, 37 (51%) drugs were good substrates of the H + OC antiporter. From 26 drugs characterized in more detail, 23 were consistently identified as substrates of the H + OC antiporter in six different assays and transport kinetic constants could be identified with intrinsic clearances between 0.2 (ephedrine) and 201 (imipramine) mL × minute−1 × g protein−1. Excellent substrates of the H + OC antiporter were no substrates of organic cation transporter OCT1 and vice versa. Good substrates of the H + OC antiporter were more hydrophobic and had a lower topological polar surface area than non-substrates or OCT1 substrates. These data and further research on the H + OC antiporter may result in a better understanding of pharmacokinetics, drug–drug interactions and variations in pharmacokinetics.

Sensitivity of Material, Microstructure and Operational Parameters on the Performance of Asymmetric Oxygen Transport Membranes: Guidance from Modeling.

Oxygen transport membranes can enable a wide range of efficient energy and industrial applications. One goal of development is to maximize the performance by the improvement of the material, microstructural properties and operational conditions. However, the complexity of the transportation processes taking place in such commonly asymmetric membranes impedes the identification of the parameters to improve them. In this work, we present a sensitivity study that allows identification of these parameters. It is based on a 1D transport model that includes surface exchange, ionic and electronic transport inside the dense membrane, as well as binary diffusion, Knudsen diffusion and viscous flux inside the porous support. A support limitation factor is defined and its dependency on the membrane conductivity is shown. For materials with very high ambipolar conductivity the transport is limited by the porous support (in particular the pore tortuosity), whereas for materials with low ambipolar conductivity the transport is limited by the dense membrane. Moreover, the influence of total pressure and related oxygen partial pressures in the gas phase at the membrane’s surfaces was revealed to be significant, which has been neglected so far in permeation test setups reported in the literature. In addition, the accuracy of each parameter’s experimental determination is discussed. The model is well-suited to guiding experimentalists in developing high-performance gas separation membranes.

PENGARUH INFORMASI AKUNTANSI TERHADAP HARGA SAHAM PERUSAHAAN MANUFAKTUR SUB SEKTOR MAKANAN DAN MINUMAN DI BURSA EFEK INDONESIA

The purpose of this study was to determine the effect of accounting information on stock prices of food and beverage sub-sector manufacturing companies on the Indonesia Stock Exchange Transportation Companies Listed on the Indonesia Stock ExchangeThis research is located at the IDX Makassar (Indonesia Stock Exchange) office. The sample selection method in this research is purposive sampling method with a total sample of 5 companies. The data collection techniques collect data on the company's financial statements during the study period. The data analysis method used is multiple regression with the help of SPSS software for windows 25.00. The results showed that 1) Based on the results of data analysis, the coefficient value of ROA, ROE, NPM, and EBIT showed the effect on stock prices simultaneously. 2) Based on the results of data analysis of ROA, ROE, NPM partially significant effect on stock prices, while EBIT has no influence on the stock prices of manufacturing companies in the food and beverage sub-sector on the IDX. 3) The most dominant variable influencing ROA, ROE, NPM and EBIT on the share prices of food and beverage sub-sector manufacturing companies on the IDX is the ROA variable.

Hydrodynamics and water quality impacts of large-scale reclamation projects in the Pearl River Estuary

The mechanism that underlies the evolution of the seasonal environment and the effects of reclamation projects in the Pearl River Estuary (PRE) were studied by modeling the hydrodynamics, suspended sediment, and water quality. Due to the seasonal variation of the freshwater discharge, the residual currents in the estuary are generally larger during the summer than during the winter. Reclamation projects significantly affect the residual current fields and decrease tidal prisms across the PRE, resulting in the variation of water exchange and material transport process. During the summer, waters high in chlorophyll-a move downstream, with increased seaward residual currents, and they more widely range from the middle estuary to the estuarine mouth than during the winter; moreover, the chlorophyll-a value peaks in these areas. Reclamation projects significantly promote the expansion of waters high in chlorophyll-a towards the estuarine mouth. The distribution of suspended sediment, nitrate, ammonium, and silicate also obviously varies with altered water exchange and chlorophyll-a distribution. Average chlorophyll-a, suspended sediment, and silicate concentrations in the whole computational domain increase by 12.71%, 15.19%, and 1.91%, respectively, while the growth of algae consumes a large amount of nitrate and ammonium.

Salinity Tolerance of Halophytic Grass Puccinellia nuttalliana Is Associated with Enhancement of Aquaporin-Mediated Water Transport by Sodium.

In salt-sensitive plants, root hydraulic conductivity is severely inhibited by NaCl, rapidly leading to the loss of water balance. However, halophytic plants appear to effectively control plant water flow under salinity conditions. In this study, we tested the hypothesis that Na+ is the principal salt factor responsible for the enhancement of aquaporin-mediated water transport in the roots of halophytic grasses, and this enhancement plays a significant role in the maintenance of water balance, gas exchange, and the growth of halophytic plants exposed to salinity. We examined the effects of treatments with 150 mM of NaCl, KCl, and Na2SO4 to separate the factors that affect water relations and, consequently, physiological and growth responses in three related grass species varying in salt tolerance. The grasses included relatively salt-sensitive Poa pratensis, moderately salt-tolerant Poa juncifolia, and the salt-loving halophytic grass Puccinellia nuttalliana. Our study demonstrated that sustained growth, chlorophyll concentrations, gas exchange, and water transport in Puccinellia nuttalliana were associated with the presence of Na in the applied salt treatments. Contrary to the other examined grasses, the root cell hydraulic conductivity in Puccinellia nuttalliana was enhanced by the 150 mM NaCl and 150 mM Na2SO4 treatments. This enhancement was abolished by the 50 µM HgCl2 treatment, demonstrating that Na was the factor responsible for the increase in mercury-sensitive, aquaporin-mediated water transport. The observed increases in root Ca and K concentrations likely played a role in the transcriptional and (or) posttranslational regulation of aquaporins that enhanced root water transport capacity in Puccinellia nuttalliana. The study demonstrates that Na plays a key role in the aquaporin-mediated root water transport of the halophytic grass Puccinellia nuttalliana, contributing to its salinity tolerance.

SGK1 in Cancer: Biomarker and Drug Target.

Serum- and glucocorticoid-regulated kinases (SGKs) are members of the AGC family of serine/threonine kinases, consisting of three isoforms: SGK1, SGK2, and SGK3. SGK1 was initially cloned as a gene transcriptionally stimulated by serum and glucocorticoids in rat mammary tumor cells. It is upregulated in some cancers and downregulated in others. SGK1 increases tumor cell survival, adhesiveness, invasiveness, motility, and epithelial to mesenchymal transition. It stimulates tumor growth by mechanisms such as activation of K+ channels and Ca2+ channels, Na+/H+ exchanger, amino acid and glucose transporters, downregulation of Foxo3a and p53, and upregulation of β-catenin and NFκB. This chapter focuses on major aspects of SGK1 involvement in cancer, its use as biomarker as well as potential therapeutic target.

Influence of the In-Stream Structure on Solute Transport in the Hyporheic Zone.

The hyporheic zone (HZ) plays an important role in the river ecosystem, and hyporheic exchange and solute transport in the HZ are important ecological functions. However, the relationship between the design parameters of river structure and solute transport is still poorly understood. In this study, we combined flume experiments and numerical simulations to systematically evaluate how in-stream structures impact the solute transport depth (DP), hyporheic vertical exchange flux (Q), and solute flux (Qs). The results showed that the in-stream structure had a significant influence on solute transport in the HZ and could obviously increase the intensity of hyporheic exchange and promote solute transport. Model results indicated that DP, Q, and Qs increased with the ratio of ground height to underground height of structure (H/D) and structure number (N), while Q, DP, and Qs increased with the structural spacing (S) to begin with; then, Q remained constant, and DP and Qs decreased as S continued to increase. This study deepened our understanding of the influence of in-stream structural design parameters on HZ solute transport, which is helpful to provide a theoretical basis for ecological restoration projects in the river HZ.

Strategies of carbon use and photosynthetic performance of the two seaweeds Gracilaria chouae and Gracilariopsis lemaneiformis under different conditions of the carbonate system

The use of Gracilaria chouae and Gracilariopsis lemaneiformis in aquaculture has recently been rapidly expanding owing to their bio- and eco-functions on coastal areas. However, high density cultures of these commercial seaweeds can lead to rapid changes in carbonate system even on a very short-term basis, which, in turn, effectively affects the physiology of these commercial seaweeds. To explore the regulation of mechanism of carbon use of G. chouae and Gp. lemaneiformis in different carbonate systems, this study exposed two seaweeds to natural seawater (control), and treatments of high CO2 and normal HCO3− concentrations (HC-NB), and natural CO2 and low HCO3− concentrations (NC-LB) to determine the net photosynthetic rate, pH drift, rapid light curves and chlorophyll fluorescence measurements. The results showed that net photosynthetic rates, non-photochemical quenching (NPQ), potential mechanism of relative electron transfer (rETRm) and the ability of both seaweeds to tolerate high light (Ik) increased significantly in the HC-NB treatment. Gp. lemaneiformis had significantly higher rates of photosynthesis and more dramatic changes in pH in all the treatments. Thalli were treated with an inhibitor of extracellular carbonic ahhydrase acetazolamide (AZ) and an anion exchange protein inhibitor 4,4′-disocyanostilbene-2,2′-disulfonate (DIDS), AZ was the primary inhibitor of HCO3− used for both seaweeds during first 2 h. However, after 24 h, DIDS and AZ were the primary inhibitors of G. chouae in all the treatments, and DIDS was the main inhibitor of Gp. lemaneiformis in the control and HC-NB treatments. In conclusion, the photosynthetic ability of G. chouae is greater in carbonate system manipulated seawaters and is more effective at metabolizing HCO3− by extracellular carbonic anhydrase at high pH values. The direct HCO3− use by the anion exchange transporter could be induced at high pH values and low [HCO3−] for both seaweeds. This study will provide a theoretical basis for seaweed aquaculture.

Dermal Lymphatic Capillaries Do Not Obey Murray's Law.

Lymphatic vessels serve as a major conduit for the transport of interstitial fluid, immune cells, lipids and drugs. Therefore, increased knowledge about their development and function is relevant to clinical issues ranging from chronic inflammation and edema, to cancer metastasis to targeted drug delivery. Murray's Law is a widely-applied branching rule upheld in diverse circulatory systems including leaf venation, sponge canals, and various human organs for optimal fluid transport. Considering the unique and diverse functions of lymphatic fluid transport, we specifically address the branching of developing lymphatic capillaries, and the flow of lymph through these vessels. Using an empirically-generated dataset from wild type and genetic lymphatic insufficiency mouse models we confirmed that branching blood capillaries consistently follow Murray's Law. However surprisingly, we found that the optimization law for lymphatic vessels follows a different pattern, namely a Murray's Law exponent of ~1.45. In this case, the daughter vessels are smaller relative to the parent than would be predicted by the hypothesized radius-cubed law for impermeable vessels. By implementing a computational fluid dynamics model, we further examined the extent to which the assumptions of Murray's Law were violated. We found that the flow profiles were predominantly parabolic and reasonably followed the assumptions of Murray's Law. These data suggest an alternate hypothesis for optimization of the branching structure of the lymphatic system, which may have bearing on the unique physiological functions of lymphatics compared to the blood vascular system. Thus, it may be the case that the lymphatic branching structure is optimized to enhance lymph mixing, particle exchange, or immune cell transport, which are particularly germane to the use of lymphatics as drug delivery routes.

Hydrodynamic and dissolved oxygen transport characteristics of an upper and lower water exchange device with regular waves

Dissolved oxygen (DO) plays an important role in seawater environment and fish farming systems. Its vertical distribution is usually non-uniform with relatively high and low values in surface and bottom water, respectively, due to the effects of natural factors including wave, seawater stratification, and eutrophication. Based on our previous study (Zhang et al., 2020), an upgraded upper and lower water exchange device was presented for strengthening the vertical water exchange and DO transport performance. A series of experiments were conducted, and a 3-D mathematical model, comprising of hydrodynamics and DO transport, was developed to investigate the characteristics of the device effect under regular waves. It was observed that wave overtopping and pressure difference are dominant factors in the water movement inside the device. The relative wave height and net flow rate inside the device are significantly dependent on the wave parameters and geometrical parameters of the device. The relative wave height increases with increases in pipe diameter and length, but decreases as wave steepness increases. The oxygen transfer coefficient roughly increases as wave height increases, and it decreases with increasing wave period and the initial average temperature in the entire water body.

Bidecadal Temperature Anomalies Over the Tibetan Plateau and Arctic in Response to the 1450s Volcanic Eruptions

AbstractVolcanic eruptions have been the most dominant natural forcing of climate change over the past millennium, affecting temperature change at multiple timescales. However, how volcanic eruptions affect regional temperature variability on the decadal timescale remains unclear. We analyzed the bidecadal effects of volcanic eruptions in the mid‐fifteenth century on two representative regions (the Tibetan plateau [TP] and the Arctic) in the Northern Hemisphere by combining proxy reconstructions, model ensemble simulations, and model sensitive experiments. The results show that the TP experienced bidecadal cooling during the mid‐fifteenth century as a result of the long‐term heat uptake in the midlatitude ocean that reduced latent heat transfer to the atmosphere. A positive sea ice–albedo feedback led to a bidecadal summer temperature decrease in the Arctic comparable to that on the TP, whereas the Arctic winter experienced stronger bidecadal cooling caused by a reduced ocean–atmosphere energy exchange and atmospheric poleward energy transport. In addition, our results show that it took ∼20 years for the temperature in these two regions to return to the level that existed before the first eruption, and this was linked to the strengthening of the Atlantic Meridional Overturning Circulation and ocean heat transport.