Surface Acidification Research Articles

Indian Ocean Acidification and Its Driving Mechanisms Over the Last Four Decades (1980–2019)

AbstractThis paper aims to study the changes in the Indian Ocean seawater pH in response to the changes in sea‐surface temperature, sea‐surface salinity, dissolved inorganic carbon (DIC), and total alkalinity (ALK) over the period 1980–2019 and its driving mechanisms using a high‐resolution regional model outputs. The analysis indicates that the rate of change of declining pH in the Arabian Sea (AS), the Bay of Bengal (BoB), and the Equatorial Indian Ocean (EIO) is −0.014 0.002, −0.014 0.001, and −0.015 0.001 unit dec−1, respectively. Both in AS and BoB (EIO), the highest (lowest) decadal DIC trend is found during 2000–2009. The surface acidification rate has accelerated throughout the IO region during 2010–2019 compared to the previous decades. Further, our analysis indicates that El Ninõ and positive Indian Ocean Dipole events lead to an enhancement of the Indian Ocean acidification. The increasing anthropogenic CO2 uptake by the ocean dominantly controls 80% (94.5% and 85.7%) of the net pH trend (1980–2019) in AS (BoB and EIO), whereas ocean warming controls 14.4% (13.4% and 7.0%) of pH trends in AS (BoB and EIO). The changes in ALK contribute to enhancing the pH trend of AS by 5.0%. ALK dominates after DIC in the EIO and, similar to the AS, contributes to increasing the negative pH trend by 10.7%. In contrast, it has a buffering effect in the BoB, suppressing the pH trend by −5.4%.

Sea surface acidification events in the Andaman Sea associated with the last Toba volcanic activity

To date, little is known about the impact of super-eruptions on ocean biogeochemistry. Using boron isotopes ratios measured on planktonic foraminifera in the marine sediment core BAR94–25, we provide a high-resolution pH record in the Andaman Sea (North of Sumatra), spanning Marine Isotopic Stage 5 to 3. This transition encompasses the super-eruption of the Toba volcano, 74,000 years ago, making it possible to decipher the potential impact of the super-eruption emissions on the ocean pH for the first time. Our results show that inferred foraminiferal pH values generally follow those predicted by glacial-interglacial CO2 variations. However, several abrupt pH drops coincide with Toba ash deposition. This suggests the occurrence of acidification events possibly related to Toba volcanic sulphur emission episodes. These pH drops are followed by anomalous pH increases, possibly relating to localised increases in seawater alkalinity following the alteration of large ash deposits on land.

Distinctive Heterogeneous Reaction Mechanism of ClNO2 on the Air-Water Surface Containing Cl.

The heterogeneous reaction of nitryl chloride (ClNO2) on the air-water surface plays a significant role in the chloride lifecycle. The air-water surface is ubiquitous on ice surfaces under supercooled conditions, affecting the uptake and heterogeneous reaction processes of trace gases. Previous studies suggest that ClNO2 is formed on Cl-doped ice surfaces following the N2O5 uptake. Herein, a distinctive heterogeneous reaction mechanism of ClNO2 is suggested on an air-water surface containing Cl under supercooled conditions using combined classic molecular dynamics (MD) and Born-Oppenheimer MD simulations. It is found that N2O5 dissociates into a NO2+ and NO3- ionic pair on the top air-water surface. In the top layer of the surface containing barely any Cl-, NO2+ proceeds through hydrolysis and produces H3O+ and HNO3. Thus, surface acidification appears because of H3O+ yields. With NO2+ diffusion to the deep layer of the surface, NO2+ reacts with Cl- and forms ClNO2. Note that ClNO2 formation competes with NO2+ hydrolysis, and the rate of ClNO2 formation is 27.7[Cl-] larger than that of NO2+ hydrolysis. Afterward, the reaction of ClNO2 with Cl- becomes barrierless with the catalysis by H3O+, which is not feasible on a neutral surface. Cl2 is thus generated and escapes into the atmosphere (low solubility of Cl2), contributing to the Cl radical. The proposed mechanism bolsters the current understanding of ClNO2's fate and its role in Cl chemistry in extremely cold environments like the Arctic and other high-latitude regions in wintertime.

Heterogeneous photochemical conversion of chlorobenzene on γ-Al2O3: A chamber experiment study

Atmospheric photochemical conversion of chlorinated volatile organic compounds (CVOCs) is crucial for secondary aerosol formation and tropospheric chlorine chemistry. However, their corresponding conversion pathways and the reaction products are lack of sufficient exploration. Herein, the photochemical conversion of chlorobenzene (CB) on the mineral γ-Al2O3 particulates was chosen as a model reaction to unveil the atmospheric chemistry of CVOCs. Chamber experiments were performed to determine the decay rates of CB with/without SO2 or NH3 under light irradiation. Reaction products were evaluated, along with the in situ diffuse reflectance infrared Fourier transform spectroscopy measurements, to explore the CB conversion pathways under different conditions. We showed that the CB could be greatly degraded by γ-Al2O3 under light irradiation, and the added SO2 significantly inhibited this conversion owing to surface acidification. However, the presence of NH3 was shown to facilitate the CB conversion by immobilizing Cl− as NH4Cl, and recovering surface oxygen vacancies for oxygen activation. In particular, we found that polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) could be generated from the photochemical CB conversion over γ-Al2O3, regardless of SO2 or NH3 coexistence, indicating a potential origin of PCDD/Fs on the atmospheric particulates from the heterogeneous photochemical CVOC conversion.

Measurement of lime movement and dissolution in acidic soils using mid-infrared spectroscopy

Acidification of surface and sub-surface soils limits agricultural production globally. Conventional surface application of lime is the most common amelioration approach for surface acidity. However, amelioration of sub-surface acidity is challenging to achieve using this approach. Testing the efficacy of liming to treat acidity through the soil profile via the measurement of lime movement requires high throughput information about soil properties at a high spatial resolution, which can be time consuming and expensive using traditional laboratory analysis. Here, we investigated the potential of Mid Infrared (MIR) spectroscopy as a tool to monitor lime dissolution and vertical movement through soils at high spatial resolution. Soil samples were collected at 2.5 cm intervals to 20 cm depth at three trial sites in South Australia, with various lime treatments applied either 6 years or 1 year prior to sampling. MIR Partial least squares regression (PLSR) predictions were undertaken to measure lime dissolution and alkalinity movement via soil pH, and undissolved lime presence via soil carbonate concentrations. Lime balance calculations were then performed to determine the fate of applied lime and assess efficacy of various rates of lime products applied at the surface only or via incorporation. MIR-PLSR prediction model performance was strong for both soil pH (R2 = 0.923 and RMSE = 0.202) and carbonate (R2 =0.829 and RMSE=0.042 CO3%). Results indicated the movement of alkalinity at all sites was limited, and revealed increased movement at the longer-term (∼6 years) vs shorter-term (∼1 year) sites where lime was surface applied. Lime balance calculations indicated that residual lime remained in the top 7.5 cm of the soil profile while soils remained acidic below this depth. Findings suggest that incorporation of residual lime and additional lime applications may be necessary to remediate sub-surface acidity. A decision tree was developed to inform management of surface and sub-surface soil acidity. The study validates the potential of MIR spectroscopy to measure and monitor the effectiveness and movement of lime with improved resolution in acidic soils.

Surface Acidification of BiOI/TiO2 Composite Enhanced Efficient Photocatalytic Degradation of Benzene

A novel BiOI/TiO2 nano-heterojunction was prepared using hydrothermal and sol-gel methods. The composite material was characterized by X-ray diffraction, ultraviolet-visible diffuse reflection spectroscopy, scanning electron microscopy, and transmission electron microscopy. The crystallinity and response to light of BiOI/TiO2 were controlled by preparation conditions such as the optimal solvent condition and heat treatment temperature. The photocatalytic activity of the BiOI/TiO2 catalyst was examined using benzene as a test molecule. The benzene degradation rate of the composite catalyst under visible light was enhanced compared to pure TiO2, thus reaching 40% of the original benzene concentration, which increased further to >60% after surface acidification. The fluorescence spectra, light current, and electron paramagnetic resonance confirmed that the enhanced activity was attributed to carrier separation by the heterojunction. The acid sites and active chlorine of hydrochloric acidification offer a novel mechanism for photocatalytic reactions.

Effects of proton pumping on the structural rigidity of cristae in mitochondria

Mitochondria change their morphology and inner membrane structure depending on their activity. Since mitochondrial activity also depends on their structure, it is important to elucidate the interrelationship between the activity and structure of mitochondria. However, the mechanism by which mitochondrial activity affects the structure of cristae, the folded structure of the inner membrane, is not well understood. In this study, the effect of the mitochondrial activity on the cristae structure was investigated by examining the structural rigidity of cristae. Taking advantage of the fact that unfolding of cristae induces mitochondrial swelling, we investigated the relationship between mitochondrial activity and the susceptibility to swelling. The swelling of individual isolated mitochondria exposed to a hypotonic solution was observed with an optical microscope. The presence of respiratory substrates (malate and glutamate) increased the percentage of mitochondria that underwent swelling, and the further addition of rotenone or KCN (inhibitors of proton pumps) reversed the increase. In the absence of respiratory substrates, acidification of the buffer surrounding the mitochondria also increased the percentage of swollen mitochondria. These observations suggest that acidification of the outer surface of inner membranes, especially intracristal space, by proton translocation from the matrix to the intracristal space, decreases the structural rigidity of the cristae. This interpretation was verified by the observation that ADP or CCCP, which induces proton re-entry to the matrix, suppressed the mitochondrial swelling in the presence of respiratory substrates. The addition of CCCP to the cells induced a morphological change in mitochondria from an initial elongated structure to a largely curved structure at pH 7.4, but there were no morphological changes when the pH of the cytosol dropped to 6.2. These results suggest that a low pH in the intracristal space may be helpful in maintaining the elongated structure of mitochondria. The present study shows that proton pumping by the electron transfer chain is the mechanism underlying mitochondrial morphology and the flexibility of cristae structure.

Improve the Photo-Activity of TiO2 from a Dual Modification via Tungsten-Doping and Fluorination

Transition metal doping is a proven feasible and practical modification technique to extend the absorption range of TiO2 from ultraviolet to visible light while retard the recombination of photogenerated electron and hole and facilitate rapid interfacial charge transfer. Surface modification also greatly influence the adsorption and reaction rate. Fluorination has become one of the most effective methods for surface acidification due to the strong electronegativity of fluorine. The ≡Ti-F group transfers electrons to the O atoms on the surface of fluorinated TiO2 to capture photoelectrons. The general modification approaches utilizing insoluble tungstic acid or highly toxic hydrofluoric acid to improve charge separation and transfer in TiO2 result in considerable issues such as uneven doping, significant impact on morphology and size, as well as serious environmental hazards. In this work, we have developed an environmental benign simple one-pot dual-modification approach that using sodium tungstate of high solubility and trace-level sodium fluoride as replacements. The combined characteristic analyses and density functional calculation (DFT) suggest that the remarkable improvement of the photo-activity of TiO2 can be attributed to the rapid charge separation and transfer due to the bandgap narrowing from tungsten doping and localized spatial charge separation from fluorination.

A transcription factor STOP1-centered pathway coordinates ammonium and phosphate acquisition in Arabidopsis

Phosphorus (P) is an indispensable macronutrient required for plant growth and development. Natural phosphate (Pi) reserves are finite, and a better understanding of Pi utilization by crops is therefore vital for worldwide food security. Ammonium has long been known to enhance Pi acquisition efficiency in agriculture; however, the molecular mechanisms coordinating Pi nutrition and ammonium remains unclear. Here, we reveal that ammonium is a novel initiator that stimulates the accumulation of a key regulatory protein, STOP1, in the nuclei of Arabidopsis root cells under Pi deficiency. We show that Pi deficiency promotes ammonium uptake mediated by AMT1 transporters and causes rapid acidification of the root surface. Rhizosphere acidification-triggered STOP1 accumulation activates the excretion of organic acids, which help to solubilize Pi from insoluble iron or calcium phosphates. Ammonium uptake by AMT1 transporters is downregulated by a CIPK23 protein kinase whose expression is directly modulated by STOP1 when ammonium reaches toxic levels. Taken together, we have identified a STOP1-centered regulatory network that links external ammonium with efficient Pi acquisition from insoluble phosphate sources. These findings provide a framework for developing possible strategies to improve crop production by enhancing the utilization of non-bioavailable nutrients in soil.

Quality assessment of GaN epitaxial films: Acidification scenarios based on XPS-and-DFT combined study

X-ray photoelectron spectroscopy (XPS) of electronic structure and surface states of GaN epitaxial films grown on Al2O3 and SiC substrates established the presence of only traces of surface oxidation after three years storage in standard air media conditions. No additional treatment was applied during this storage process. The slight shift (~1 eV) of Valence Band (VB) spectra was found which occurs without any visible contribution of gallium oxide electronic states to the valence band area. Additionally, GaN-typical N 2s band is present in VB-spectra of studied epitaxial films what is confirming their high quality grade. First-principle modelling demonstrates favorability of GaN surface acidification because of humidity and much slower oxidation process in the dry-air conditions. Theoretical models of acidification scenarios also demonstrate that oxidation of defect-free and defective surfaces (N-vacancies) are a good leveler: electronic structures of all considered surfaces became almost identical that is in a perfect agreement with results of XPS measurements and analytics.

Mechanisms Driving Decadal Changes in the Carbonate System of a Coastal Plain Estuary

AbstractUnderstanding decadal changes in the coastal carbonate system is essential for predicting how the health of these waters responds to anthropogenic drivers, such as changing atmospheric conditions and riverine inputs. However, studies that quantify the relative impacts of these drivers are lacking. In this study, the primary drivers of decadal trends in the surface carbonate system, and the spatiotemporal variability in these trends, are identified for a large coastal plain estuary: the Chesapeake Bay. Experiments using a coupled three‐dimensional hydrodynamic‐biogeochemical model highlight that, over the past three decades, the changes in the surface carbonate system of Chesapeake Bay have strong seasonal and spatial variability. The greatest surface pH and aragonite saturation state (ΩAR) reductions have occurred in the summer in the middle (mesohaline) Bay: −0.24 and −0.9 per 30 years, respectively, with increases in atmospheric CO2 and reductions in nitrate loading both being primary drivers. Reductions in nitrate loading have a strong seasonal influence on the carbonate system, with the most pronounced decadal decreases in pH and ΩAR occurring during the summer when primary production is strongly dependent on nutrient availability. Increases in riverine total alkalinity and dissolved inorganic carbon have raised surface pH in the upper oligohaline Bay, while other drivers such as atmospheric warming and input of acidified ocean water through the Bay mouth have had comparatively minor impacts on the estuarine carbonate system. This work has significant implications for estuarine ecosystem services, which are typically most sensitive to surface acidification in the spring and summer seasons.

The Effects of Surface Modification of ATP on the Performance of CeO2–WO3/TiO2 Catalyst for the Selective Catalytic Reduction of NOx with NH3

A series of CeO2–WO3/20%ATP-TiO2 catalysts were synthesized, of which attapulgite (ATP) was modified by different methods. Notably, after ATP was dissociated and acidified, the catalyst synthesized by the impregnation method exhibited satisfactory performance for selective catalytic reduction (SCR) NOx with NH3. In more detail, the NO conversion could reach to 88% at 240 °C and maintain above 93% in the temperature range of 280–400 °C. Subsequently, the NO conversion of the best catalyst could keep above 80% after introducing H2O and SO2, so this catalyst also had strong tolerance to H2O and SO2 performance. Besides, the results of XRD, XPS, TEM characterizations suggested that the high dispersion of active species cerium and tungsten on the surface of ATP, which played an important role in improving the SCR performance of the catalyst. In short, the surface dissociation and surface acidification of a small amount of ATP carrier can improve the catalyst catalytic performance, so it will have a broad application prospect in SCR reaction.

Alkalinization Scenarios in the Mediterranean Sea for Efficient Removal of Atmospheric CO2 and the Mitigation of Ocean Acidification

It is now widely recognized that in order to reach the target of limiting global warming to well below 2°C above pre-industrial levels (as the objective of the Paris agreement), cutting the carbon emissions even at an unprecedented pace will not be sufficient, but there is the need for development and implementation of active Carbon Dioxide Removal (CDR) strategies. Among the CDR strategies that currently exist, relatively few studies have assessed the mitigation capacity of ocean-based Negative Emission Technologies (NET) and the feasibility of their implementation on a larger scale to support efficient implementation strategies of CDR. This study investigates the case of ocean alkalinization, which has the additional potential of contrasting the ongoing acidification resulting from increased uptake of atmospheric CO2 by the seas. More specifically, we present an analysis of marine alkalinization applied to the Mediterranean Sea taking into consideration the regional characteristics of the basin. Rather than using idealized spatially homogenous scenarios of alkalinization as done in previous studies, which are practically hard to implement, we use a set of numerical simulations of alkalinization based on current shipping routes to quantitatively assess the alkalinization efficiency via a coupled physical-biogeochemical model (NEMO-BFM) for the Mediterranean Sea at 1/16° horizontal resolution (~6 km) under an RCP4.5 scenario over the next decades. Simulations suggest the potential of nearly doubling the carbon-dioxide uptake rate of the Mediterranean Sea after 30 years of alkalinization, and of neutralizing the mean surface acidification trend of the baseline scenario without alkalinization over the same time span. These levels are achieved via two different alkalinization strategies that are technically feasible using the current network of cargo and tanker ships: a first approach applying annual discharge of 200 Mt Ca(OH)2 constant over the alkalinization period and a second approach with gradually increasing discharge proportional to the surface pH trend of the baseline scenario, reaching similar amounts of annual discharge by the end of the alkalinization period. We demonstrate that the latter approach allows to stabilize the mean surface pH at present day values and substantially increase the potential to counteract acidification relative to the alkalinity added, while the carbon uptake efficiency (mole of CO2 absorbed by the ocean per mole of alkalinity added) is only marginally reduced. Nevertheless, significant local alterations of the surface pH persist, calling for an investigation of the physiological and ecological implications of the extent of these alterations to the carbonate system in the short to medium term in order to support a safe, sustainable application of this CDR implementation.

Ongoing increases in dissolved organic carbon are sustained by decreases in ionic strength rather than decreased acidity in waters recovering from acidic deposition

Dissolved organic carbon (DOC) has received considerable attention in freshwater research, particularly since the early 2000s when increasing trends became apparent. However, remaining questions need to be resolved to address future effects of DOC on surface waters. This study was undertaken to determine (1) the relative importance of acidity and ionic strength in driving DOC increases in waters recovering from acidification and (2) the role played by long-term acid rain effects on soil. Data obtained from temporal and spatial monitoring of 142 headwater streams throughout the Adirondack region of New York (USA) were used to evaluate chemical relationships involving DOC. Year-round monitoring of three streams of differing acidification status were combined with intermittent stream surveys during spring snowmelt throughout this 24,243 km2 region that is recovering from acidification of soils and surface waters.Despite acidic deposition decreases reaching levels estimated for the early 1900s, DOC concentrations exhibited linear increases from the early 2000s through 2019. Ionic strength or conductivity showed consistent inverse relationships with DOC in all data comparisons from 2004‐05 to 2018‐19. In contrast, relationships between pH and DOC did not support increasing pH as an important factor in DOC increases. Inconsistent relationships between pH and DOC were due to strongly acidic organic acids that remain unprotonated throughout the pH range of these waters and limited weak-acid deprotonation below pH 6.2. Decreasing ionic strength increases DOC solubility by expanding the diffuse double layer, which fosters disaggregation of organic matter and dispersion of colloids. This affect controlled DOC solubilization below a pH of approximately 6.2. Distinguishing between ionic strength and pH effects is important because further large reductions in acidic deposition are not expected but continued soil-water dilution is likely from soil-Ca2+ depletion and the decreasing rate of Ca2+ leaching by SO42− and NO3−, which are still being released from soil organic matter.

Ammonia mitigation effects from the cow housing and manure storage chain on the nitrogen and carbon footprints of a typical dairy farm system on the North China Plain

Atmospheric ammonia is an important air pollutant, while dairy production is a significant source of ammonia emissions. The aim of the present dairy manure management study was to analyze: 1) the impacts of acidification of the manure surface and/or a vermiculite cover on ammonia, nitrous oxide and methane emissions from animal housing and manure storage stages, 2) the potential influence on the reactive nitrogen (N) and carbon (C) footprints of milk from cradle-to-farm-gate. It was based on a consecutive incubation trial and a life cycle assessment approach for a typical dairy farm system on the North China Plain. Trial results showed that surface-acidification of manure under a slatted floor could reduce ammonia emission by 98 and 22% from housing (one day) and storage stages (38 days), respectively, with small effects on nitrous oxide and methane emissions. The vermiculite cover (storage stage only) reduced ammonia emissions by 98% and methane by 58%, but increased nitrous oxide emissions from storage by almost six times with small absolute losses. The combination of the two mitigations retained 90% of the manure N post-storage relative to that at the start of the housing stage. Life cycle assessment indicated that the reactive-N footprint (NF, i.e. reactive N loss per kg fat- and protein-corrected milk) of milk production was dominated by ammonia emissions and was reduced by 10, 33 and 38% in the manure acidification, manure cover and combination treatments, respectively. Acidification of the manure surface, the vermiculite cover and combination treatments decreased the C footprint (CF, i.e. total greenhouse gas emissions per kg fat- and protein-corrected milk) by 1.0, 1.9 and 2.4%, respectively. This holistic analysis, combining incubation trials and life cycle assessment, indicates that surface-acidification of manure under the slatted floor and a vermiculite cover during manure storage can reduce ammonia emission from a dairy farm system, with an overall positive influence on reduction of NF and CF for dairy farm systems.

Twenty-first century ocean warming, acidification, deoxygenation, and upper-ocean nutrient and primary production decline from CMIP6 model projections

Abstract. Anthropogenic climate change is projected to lead to ocean warming, acidification, deoxygenation, reductions in near-surface nutrients, and changes to primary production, all of which are expected to affect marine ecosystems. Here we assess projections of these drivers of environmental change over the twenty-first century from Earth system models (ESMs) participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6) that were forced under the CMIP6 Shared Socioeconomic Pathways (SSPs). Projections are compared to those from the previous generation (CMIP5) forced under the Representative Concentration Pathways (RCPs). A total of 10 CMIP5 and 13 CMIP6 models are used in the two multi-model ensembles. Under the high-emission scenario SSP5-8.5, the multi-model global mean change (2080–2099 mean values relative to 1870–1899) ± the inter-model SD in sea surface temperature, surface pH, subsurface (100–600 m) oxygen concentration, euphotic (0–100 m) nitrate concentration, and depth-integrated primary production is +3.47±0.78 ∘C, -0.44±0.005, -13.27±5.28, -1.06±0.45 mmol m−3 and -2.99±9.11 %, respectively. Under the low-emission, high-mitigation scenario SSP1-2.6, the corresponding global changes are +1.42±0.32 ∘C, -0.16±0.002, -6.36±2.92, -0.52±0.23 mmol m−3, and -0.56±4.12 %. Projected exposure of the marine ecosystem to these drivers of ocean change depends largely on the extent of future emissions, consistent with previous studies. The ESMs in CMIP6 generally project greater warming, acidification, deoxygenation, and nitrate reductions but lesser primary production declines than those from CMIP5 under comparable radiative forcing. The increased projected ocean warming results from a general increase in the climate sensitivity of CMIP6 models relative to those of CMIP5. This enhanced warming increases upper-ocean stratification in CMIP6 projections, which contributes to greater reductions in upper-ocean nitrate and subsurface oxygen ventilation. The greater surface acidification in CMIP6 is primarily a consequence of the SSPs having higher associated atmospheric CO2 concentrations than their RCP analogues for the same radiative forcing. We find no consistent reduction in inter-model uncertainties, and even an increase in net primary production inter-model uncertainties in CMIP6, as compared to CMIP5.

FISH OTOLITHS FROM THE LATE MAASTRICHTIAN KEMP CLAY (TEXAS, USA) AND THE EARLY DANIAN CLAYTON FORMATION (ARKANSAS, USA) AND AN ASSESSMENT OF EXTINCTION AND SURVIVAL OF TELEOST LINEAGES ACROSS THE K-PG BOUNDARY BASED ON OTOLITHS

Otolith assemblages have rarely been studied across the K-Pg boundary. The late Maastrichtian Kemp Clay of northeastern Texas and the Fox Hills Formation of North Dakota, and the early Danian Clayton Formation of Arkansas therefore offer new insights into how teleost fishes managed across the K-Pg boundary as reconstructed from their otoliths. The Kemp Clay contains 25 species, with 6 new species and 2 in open nomenclature and the Fox Hills Formation contains 4 species including 1 new species. The two otolith associations constitute the Western Interior Seaway (WIS) community. It contains the earliest unambiguous representatives of the Gadiformes (cods and hakes) and the Heterenchelyidae (mud eels). The WIS community differs significantly from other Maastrichtian otolith assemblages previously studied from Mississippi and Maryland, which constitute the Appalachian community, with only 4 shared species (similarity percentage of 7.3%) between both communities. The difference is interpreted to be related to cold-water influence in the WIS community, which may have still been connected to the Arctic Basin, and to the depostional environment (muddy bottom) in the Kemp Clay. The Kemp Clay is unusually rich in taxa that survived the end-Cretaceous extinction event and are still present in the Danian of the Clayton Formation, or, as the case may be, in the Danian and Selandian of the boreal northern European community known from Denmark. Approximately 54% of all otolith-based teleost species identified from the Maastrichtian WIS community survived the K-Pg boundary event (versus 11-12% in other communities) and 73% of the genera (versus 40-50% in other communities). The early Danian Clayton Formation contains an impoverished inherited association with 14 species, of which 11 are survivors from late Maastrichtian times, 1 species is new, and 2 remain in open nomenclature. This compares to a significantly higher degree of newly evolved species in only slightly younger faunas from the middle to late Danian and Selandian of Europe indicating an initially slow pace of recovery. The observed differences in survival and the composition of survived and extinct taxa are discussed in the light of the ongoing discussions concerning the consequences and effects that led to the end-Cretaceous extinction event commonly thought to have been caused by a large meteorite impact. In our assessment, an ‘impact winter’ could have had a major influence on the live cycle of tropical to subtropical fishes while perturbations in the pelagic food web or ocean surface acidification might have had a minor and more selective effect. Overall, teleost fishes were significantly affected by the end-Cretaceous mass extinction, but to a much lesser extent than in many other biota. This study provides more evidence of the importance of Late Cretaceous otolith assemblages in the USA for interpreting teleostean evolution. The newly described taxa are: Elopothrissus carsonsloani n. sp., Pythonichthys arkansasensis n. sp., Congrophichthus transterminus n. gen., n. sp., Rhynchoconger brettwoodwardi n. sp., Palaeogadus weltoni n. sp., Dakotaichthys hogansoni n. gen., n. sp., and Ampheristus americanus n. sp.

The Magnitude of Surface Ocean Acidification and Carbon Release During Eocene Thermal Maximum 2 (ETM‐2) and the Paleocene‐Eocene Thermal Maximum (PETM)

AbstractEocene Thermal Maximum 2 (ETM‐2; 54.1 Ma) was the second largest Eocene hyperthermal. Like the Paleocene‐Eocene Thermal Maximum (PETM), ETM‐2 was characterized by massive carbon emissions and several degrees of global warming and thus can serve as a case study for assessing the impacts of rapid CO2 emissions on ocean carbonate chemistry, biota, and climate. Marine carbonate records of ETM‐2 are better preserved than those of the PETM due to more subdued carbonate dissolution. As yet, however, the magnitude of this carbon cycle perturbation has not been well constrained. Here, we present the first records of surface ocean acidification for ETM‐2, based on stable boron isotope records in mixed‐layer planktic foraminifera from two midlatitude ODP sites (1210 in the North Pacific and 1265 in the SE Atlantic), which indicate conservative minimum global sea surface acidification of −0.20 +0.12/−0.13 pH units. Using these estimates of pH and temperature as constraints on carbon cycle model simulations, we conclude that the total mass of C, released over a period of 15 to 25 kyr during ETM‐2, likely ranged from 2,600 to 3,800 Gt C, which is greater than previously estimated on the basis of other observations (i.e., stable carbon isotopes and carbonate compensation depth) alone.

POSTNATAL ADAPTATION OF THE SKIN IN NEWBORNS

The first days after birth is a very crucial period of active functional adjustment and physiological adaptation of the baby’s skin to the ectopic environment. The skin as an external organ has many functions, such as protection, secretion, absorption and thermoregulation. The birth of a child stimulates the maturation of the epidermal barrier and acidification of the skin surface, especially in prematurely born children. Full-term newborns are more morpho-functionally mature; they have a developed stratum corneum, which performs a competent barrier function, unlike premature infants. Full barrier maturation in premature babies is achieved after 2–4 weeks of postnatal life; in preterm babies with a gestational age of 23–25 weeks, this process takes longer.The skin of newborns quickly adapts to the difficult environmental conditions after childbirth. However, some functions, such as microcirculation, continue to develop even after the neonatal period, that is, until the age of 14-20 weeks. Various environmental factors (for example, dry and cold air, diapers and beauty treatments) affect the postnatal development of the skin’s functional parameters, such as the hydration of the stratum corneum and the permeability barrier, especially in premature babies.The purpose of this article is to analyze individual current knowledge of the physiology of the skin in newborns and infants with a practical approach and discussion of possible clinical consequences. High-quality and complete skin care for a newborn baby is very important for effective prevention of irritation and diaper dermatitis, and parents require validated information on measures of high-quality skin care for the baby and the algorithm for helping the child. It is JOHNSON'S® that provides a complete link of baby skin care products with proven quality and effectiveness.

Humic acids and Herbaspirillum seropedicae change the extracellular H+ flux and gene expression in maize roots seedlings

BackgroundThe use of plant-based biostimulants to increase crop yield and enhance protection has grown in popularity. We previously manufactured an inoculant combining humic acids with plant growth-promoting bacteria and observed a significant effect on crop yields. However, electrophysiology studies elucidating the mechanisms responsible for enhanced nutrient and water uptake are scarce and are generally restricted to in vitro models.Materials and methodsIn this study, a suspension of humic acids isolated from vermicompost along with Herbaspirillum seropedicae was applied to maize seedlings. We measured the root H+ flux with an ion-selective vibrating probe system. Furthermore, the transcription of plasma membrane H+ ATPase, aquaporin and high- or low-affinity nitrate transporters was measured.ResultsInoculation activated the extracellular H+ flux, thus changing the pH and membrane potential of maize root cells and altering the electrochemical potential generated by P–H+-ATPase at the biochemical and molecular level. The overexpression of aquaporins was also observed; however, nitrate transporters were repressed by the inoculants.ConclusionWe demonstrate an increase in the H+ efflux in maize root seedlings inoculated with H. seropedicae and concomitant changes in membrane voltage. The inoculation of H. seropedicae in the presence of humic acids decreased the H+ flux and surface acidification without changes in the aquaporin transcription level. However, the H+ flux in root seedlings in inoculated plants (with or without humic acids) was larger in respect to control plants. These results support the increased water and nitrogen efficiency in plants inoculated with humic acids and H. seropedicae.