Dry Intervals Research Articles

Analyzing rain erosion using a Pulsating Jet Erosion Tester (PJET): Effect of droplet impact frequencies and dry intervals on incubation times

Accelerated laboratory testing is essential to understand the rain erosion behavior of coated samples applied to the leading edge surface of a wind turbine blade. This study investigates the impact of droplet impact frequencies and dry intervals on the incubation time for damage on polyurethane-coated samples using a Pulsating Jet Erosion Tester (PJET). A novel theoretical model for water slug volume is introduced, allowing for a more accurate comparison across different impact velocities and frequencies. The effect of dry intervals on coating performance is quantified, revealing that longer dry intervals and shorter pre-dry rain exposure can significantly increase the number of impacts a coating can withstand before damage. The study challenges the traditional continuous impingement testing by demonstrating that dry intervals can extend incubation time by a factor of three to five. Additionally, this paper proposes a recalibrated approach to PJET testing, which better mimics the cyclic nature of real-world rainfall, leading to improved predictive models for material degradation. The findings emphasize the importance of considering the visco-elastic behavior of coatings and the role of intermittent rain exposure in erosion testing, offering invaluable insights for designing future PJET test parameters.

High resolution stable isotope ratios in modern African land snails: Testing inferred environmental conditions

High-resolution sub-annual stable oxygen isotope data were measured in modern land snail shells collected from different climatic zones in Africa to search for patterns in seasonal δ18O cycles associated with specific hydroclimates, keyed to flora/biozones. Thirty-three recently dead shells were collected between 1995 and 2012, and collection localities were divided into five climate types: tropical forest, woodland savannah, bushland savannah, woodland monsoon, and arid/semi-arid. Thirteen genera are represented in the collection. Sampling covered at least one year in the life of the land snails, often multiple years. A comparison of measured data to predicted δ18O values, using local temperature and rain δ18O value, shows that predictions tend to be lower than measured values, suggesting that surface waters or snail body waters have undergone some evaporation. Predictions based on night-time temperatures (average monthly minimum T) are closer to, but still underestimate, measured values compared to day-time (maximum) temperatures in a majority of cases. The largest range in δ18O values for individual shells occurs in the bushland savannah and woodland monsoon biomes. Longer seasonal intervals of dry conditions lead to greater δ18O ranges in shells, although if the dry interval approaches 10 months in the year the amplitude is again reduced. This is in agreement with other oxygen isotope studies of high-resolution land snail shell samples, which show very high δ18O variance in strong monsoon climates.

Late Pleistocene–Holocene palynology and paleoceanography of İmralı Basin, Marmara Sea: Pollen-spore, dinoflagellate cyst and other NPP zonations

The Marmara Sea is the oceanographic gateway that links the hypersaline Eastern Mediterranean Sea with the hyposaline Black Sea via Straits of Dardanelles and Bosphorus, respectively, and also occupies a transitional vegetation and climatic regime between the Mediterranean and Euxinic phytogeographic ecosystems. Recent palynological studies of long cores from the shallow İmralı Basin perched on the southeastern slope of the Marmara Sea reveal that major paleoecological changes accompanied the isolation and reconnection of the Marmara Sea during the last two Pleistocene glacial–interglacial cycles. Here, we use data primarily from two İmralı Basin cores to determine new quantitative zonations for the pollen-spore, dinoflagellate cyst (dinocyst) and other non-pollen palynomorph (NPP) assemblages in sediments representing the last ∼30 cal ka. A gap in one core is closed using data from three short gravity cores. Twenty-four radiocarbon ages and 20 correlation-ties for sapropel and ash layers from these five cores provide an essentially complete record for the past 30 cal ka. Use of a full suite of palynomorph data (pollen and spores, fungal spores, dinocysts and other phytoplankton, aquatic parasites/saprophytes, zoo-planktonic and zoo-benthic NPPs) shows for the first time that fluctuations in aquatic palynoassemblages during the glacial periods are more complex than simple salinity or temperature responses. The changes involve food web-level turnovers in trait- and size-based food web components in which potential parasites/saprophytes appear critically important.Pollen stratigraphies reveal a significant loss of Euxinic tree taxa by MIS 3c, with only partial recovery in MIS 1. The Euxinic forest elements are replaced by cultivars and other indicators of anthropogenic influences during the MIS 1 that is also marked by a dry interval and corresponding in part with the 4.2 cal ka Eastern Mediterranean Drought Event. The dinocyst zones for the last ∼30 cal ka show a clear turnover from assemblages dominated by brackish Ponto–Caspian taxa to marine assemblages at ∼11.7 cal ka. This phytoplanktonic signal lags slightly behind (a) the vegetation and shift in the other NPP commencing ∼13.2 cal ka, the initial marine incursion at 13.8 cal ka, and the arrival of coccolithophores at ∼13 cal ka. Comparison to published MIS 6 and 5 data reveals higher MIS 2–1 species diversity, reappearance of the MIS 6 marker Impagidinium inaequalis, and the emergences of Pyxidinopsis psilata f. quadrata, cf. Boreadinium breve, and Peridinium spp. of Brenner 2005. The pre-reconnection microbiota is dominated by the unicellular alga Sigmopollis, spikes of colonial Pediastrum algae, the saprophytes/parasites cf. Multiplicisphaeridium and Chytridiomycota. This microbiota is displaced by the post-reconnection assemblage dominated by Botryococcus coenobia, various Platyhelminth egg capsules and ostracod lining-types that persist through the Holocene. A distinctive transitional microbiota with Discocotyle-type turbellarian egg capsules marks the Bølling–Allerød warming, followed at ∼13.3 ka by a marine assemblage with micro-foraminiferal linings and crustacean eggs. The interglacial marine phase of MIS 1 in İmralı Basin has much higher dinocyst species diversity than MIS 5e, reflecting Neolithic impacts (agriculture, land clearance) and expanded shipping trade. Initial marine flooding in the Marmara Sea during both interglacials are marked by sapropel deposition but variations of ravinement surface erosion, and marine deep water residence time in a stratified Marmara Sea are potentially important factors underlying hypoxia/anoxia and sapropel deposition.

Soil Bacterial and Archaeal Communities of the Periodic Flooding Zone of Three Main Reservoirs in the South Ural Region (Russia)

Studying the soils in the periodical flood zone of three reservoirs is of promising importance for their subsequent return to economic activities. Research on the bacterial and archaeal communities of soils that are periodically or continuously flooded by reservoirs is still insufficient. To evaluate the chemical status of soils and their microbiota, the study was conducted in the Yumaguzino, Nugush, and Slak reservoir sites in the South Ural area (Russian Federation). The bacterial and archaeal communities of periodically flooded and non-flooded soils were investigated after a comparative investigation of chemical, hydrological, and climatic factors. It was discovered that flooded soils had anoxic conditions during the whole of the year, with brief drying intervals of limited length and low levels of effective temperatures. In terms of chemistry, flooded soils are distinguished by increased acidity, a fall in organic matter, and an increase in alkali-hydrolysable nitrogen. Compared to their counterparts in non-flooded soils, bacterial and archaeal communities in flooded soils are significantly different. Generally speaking, the biodiversity of flooded soils rises with the duration and depth of floods. Significant variations at the phylum level are mostly caused by a decline in the relative presence of Thaumarchaeota and an increase in Proteobacteria and Chloroflexi representation. It was discovered that the Euryarchaeota phylum was either absent or had a significantly decreased relative prevalence at the sites of intermittently flooding soils.

Multi-Institutional Bladder Exstrophy Consortium After 8 Years: The Short- and Intermediate-Term Outcomes.

Bladder exstrophy (BE) poses challenges both during the surgical repair and throughout follow-up. In 2013, a multi-institutional BE consortium was initiated, which included utilization of unified surgical principles for the complete primary repair of exstrophy (CPRE), real-time coaching, ongoing video capture and review of video footage, prospective data collection, and routine patient data analysis, with the goal of optimizing the surgical procedure to minimize devastating complications such as glans ischemia and bladder dehiscence while maximizing the rate of volitional voiding with continence and long-term protection of the upper tracts. This study reports on our short-term complications and intermediate-term continence outcomes. A single prospective database for all patients undergoing surgery with a BE epispadias complex diagnosis at 3 institutions since February 2013 was used. For this study, data for children with a diagnosis of classic BE who underwent primary CPRE from February 2013 to February 2021 were collected. Data recorded included sex, age at CPRE, adjunct surgeries including ureteral reimplantations and hernia repairs at the time of CPRE, osteotomies, and immobilization techniques, and subsequent surgeries. Data on short-term postoperative outcomes, defined as those occurring within the first 90 days after surgery, were abstracted. In addition, intermediate-term outcomes were obtained for patients operated on between February 2013 and February 2017 to maintain a minimum follow-up of 4 years. Outcomes included upper tract dilation on renal and bladder ultrasound, presence of vesicoureteral reflux, cortical defects on nuclear scintigraphy, and continence status. Bladder emptying was assessed with respect to spontaneous voiding ability, need for clean intermittent catheterization, and duration of dry intervals. All operating room encounters that occurred subsequent to initial CPRE were recorded. CPRE was performed in 92 classic BE patients in the first 8 years of the collaboration (62 boys), including 46 (29 boys) during the first 4 years. In the complete cohort, the median (interquartile range) age at CPRE was 79 (50.3) days. Bilateral iliac osteotomies were performed in 89 (97%) patients (42 anterior and 47 posterior). Of those undergoing osteotomies 84 were immobilized in a spica cast (including the 3 patients who did not have an osteotomy), 6 in modified Bryant's traction, and 2 in external fixation with Buck's traction. Sixteen (17%) patients underwent bilateral ureteral reimplantations at the time of CPRE. Nineteen (21%) underwent hernia repair at the time of CPRE, 6 of which were associated with orchiopexy. Short-term complications within 90 days occurred in 31 (34%), and there were 13 subsequent surgeries within the first 90 days. Intermediate-term outcomes were available for 40 of the 46 patients, who have between 4 and 8 years of follow-up, at a median of 5.7 year old. Thirty-three patients void volitionally, with variable dry intervals. Cumulative efforts of prospective data collection have provided granular data for evaluation. Short-term outcomes demonstrate no devastating complications, that is, penile injury or bladder dehiscence, but there were other significant complications requiring further surgeries. Intermediate-term data show that boys in particular show encouraging spontaneous voiding and continence status post CPRE, while girls have required modification of the surgical technique over time to address concerns with urinary retention. Overall, 40% of children with at least 4 years of follow-up are voiding with dry intervals of > 1 hour.

Holocene hydroclimate in highland Costa Rica: new evidence from hydrogen and carbon isotopes in n‐alkanes of terrestrial leaf waxes in a 10 000‐year sediment profile

ABSTRACTWe conducted compound‐specific stable hydrogen (δD) and carbon (δ13C) isotope analysis on n‐alkanes from terrestrial leaf waxes preserved in a 10 000‐year sediment profile from Lago de las Morrenas 1 (9.4925° N, 83.4848° W, 3480 m), a glacial lake on the Chirripó massif of the Cordillera de Talamanca in Costa Rica. Our results demonstrate millennial‐scale variations in hydroclimate across the Holocene, with drier than average conditions in the highlands during the early Holocene, but with gradually increasing precipitation; mesic conditions during the middle Holocene with a gradual drying trend; and highly variable conditions during the late Holocene. This general pattern is punctuated by several centennial‐scale manifestations of global climate events, including dry conditions during the 8200, 5200 and 4200 cal a bp events and the Terminal Classic Drought (1200–850 cal a bp). Our δ13C analyses demonstrate that carbon isotope signals are responding to changes in hydroclimate at the site and reinforce prior interpretations of a stable páramo plant community that established following deglaciation and persisted throughout the Holocene. The shifts in hydroclimate inferred from analyses of n‐alkanes in Lago de las Morrenas 1 sediments show correspondence with charcoal records in multiple lakes, with fires most common during drier intervals.

Collateral benefits: River flow normalization for endangered fish enabled riparian rejuvenation

AbstractLike most rivers worldwide, the transboundary North American Kootenay/i River has experienced multiple impacts including watershed developments, river channelization, and floodplain clearing, draining, and diking. Construction of Libby Dam was authorized by the 1964 Columbia River Treaty (CRT) between the United States and Canada, and in 1975 began regulating downstream flows for flood risk management and hydropower generation. Following cumulative impacts, the endemic Kootenai River White Sturgeon population collapsed and was designated as endangered in 1994 (U.S. Endangered Species Act). Subsequent Biological Opinions from the U.S. Fish and Wildlife Service prescribed Libby Dam operations to provide springtime flow pulses for sturgeon spawning. These provided the unanticipated benefit of substantial seedling recruitment of native and introduced riparian cottonwoods and willows. The regulated flow regime was further adaptively managed to provide a more normative (natural) regime, to balance ecological functions with flood risk management and hydropower generation. The broadened ecological considerations would be consistent with the proposed priorities for the modernization of the international CRT. The observed responses revealed that (1) diverse aquatic and riparian organisms are dependent on common river flow characteristics; (2) a normalized flow regime provided substantial ecological benefits; and (3) due to multiple influences, hybrid ecosystems develop along regulated rivers, with a blending of natural and altered processes and communities. For other regulated rivers, we recommend that (1) high springtime flows be allowed, as feasible; (2) followed by the gradual post‐peak recession; and (3) the maintenance of sufficient flows through the warm and dry interval of mid to late summer.

Macedo ileal catheterizable reservoir adding the scissors maneuver of channel continence: Long term follow-up

The Macedo ileal catheterizable channel was published in 2000 and consists of an enterocystoplasty with a catheterizable channel that precludes the need of the appendix for the efferent channel. After 25 years of experience with this technique, we decided to review our experience in a select subgroup of cases performed and followed exclusively by the author in a non-teaching hospital facility after the latest modifications of the procedure. Since 2008, we have refined our technique with the following modifications: small skin transverse incision instead of longitudinal one, with a semicircular flap for further stoma creation in the midline and importantly the scissors maneuver. This maneuver consists of crossing two 2cm rectus abdominis muscle flaps in the midline to create a neosphincter over the catheterizable channel. Follow-up was defined as the interval between the date of surgery and last visit to the clinic. We defined stoma continence if the dry interval between catheterization was 4hs. Early and late complications were reported as well as the reintervention rate. Additional procedures in association with bladder augmentation were also appointed. We have treated 49 patients. Indications were spinal dysraphism (71.4%), mainly myelomeningocele (65.3%), and others (PUV, exstrophy, anorectal anomalies). Urodynamic evaluation showed bladder pressure of high risk for upper urinary tract involvement (66%), urinary incontinence (24.5%), conversion of incontinent urinary diversion (3.8%), one exstrophy patient not considered (1.9%). Mean age at surgery was 88 months (7.3 years), 21 patients had additional surgeries in addition to Macedo ileal catheterizable channel: Macedo-Malone LACE procedure in 21 patients and bladder neck surgery to improve continence in 5 patients. Urinary stoma continence was 93.9% (46/49) after first surgery, one patient had a serous line valve revised, two patients still leak after 2h and await revision. Overall enterocystoplasty complications rate was 12.24% and consisted of urinary leakage in 3 cases and channel/stoma stricture in 3 cases. All patients treated for sphincteric deficiency associated with bladder reconstruction are continent per urethra. Urinary stoma revision for stricture was done in 2 cases and consisted on suprafascial approach and reanastomosis, one patient resolved with dilatation of the channel to the stoma. Mean follow up is 100 months (8.3 years). We confirmed in a long term follow-up based on face-to-face visits with 8.3 years mean follow-up that the Macedo procedure associated with the scissors maneuver is associated with 93.9% continence of the stoma. Overall complications rate was 12.24%. The cosmetic aspect with a small transverse incision and a midline stoma is another strength of the technique.

Paleoclimatic and paleoenvironmental significance of late Pleistocene pedogenic carbonates (‘Caliche Cordão’) from the coastal Pampa of southern Brazil

The pedogenic carbonates found in Pleistocene units of the coastal Brazilian Pampa, informally designated as ‘Caliche Cordão', include rhizocretions, soft masses and isolated or coalescent nodules, either isolated within the sediment or forming discrete horizons, the most developed horizons (Ca-01 and Ca-02) stretching for hundreds of meters along the banks of Chuy Creek. Petrographic analyses show micritic (Alpha-type) matrix in most samples, with few signs of recrystallization as circumgranular spar rims or cracked sand grains. Stable carbon (δ13C) and oxygen (δ18O) isotope values in samples from the lower horizon Ca-01 exhibit small variation and indicate C3-dominated plant assemblages and carbonate precipitation from relatively 18O-enriched water, whereas the δ13C and δ18O in samples from the upper horizon (Ca-02) exhibit wider variation, higher proportion of C4 plants and precipitation from 18O-depleted water in some samples. The δ18O variations can be explained by variable degrees of evaporative enrichment, or to relative contributions of 18O-depleted (tropical) or 18O-enriched (subtropical) rainfall, based on the similarity with estimates from fossils of mastodons. Nodules from other sites are similar, but larger isotopic variations indicate carbonate precipitation at distinct times and environmental conditions, and a few exhibit partial recrystallization as larger spar calcite crystals. Luminescence ages of ∼74.7 and ∼71.3 ka of quartz grains in two nodules from Ca-01 indicate precipitation during MIS 4, whereas ages of ∼52 ka from Ca-02, and ≥30 ka in nodules from the shores of Mirim Lagoon indicate carbonate formation between MIS 3 and MIS 2. The probable source of carbonate was calcium released from eolian-sourced silty dust produced by Andean glaciers and transported from loess deposits in Argentina during cold and dry intervals of the last glacial, when arid/semiarid environments expanded from Patagonia across the Pampas up to southern Brazil. The variations of δ13C in calcretes formed between MIS 4 and 2 point to changes in plant assemblages that could have contributed for the local extinction of the mammalian megafauna.

Comment on “Five Decades of Observed Daily Precipitation Reveal Longer and More Variable Drought Events Across Much of the Western United States”

AbstractChanges in precipitation patterns with climate change could have important impacts on human and natural systems. Zhang et al. (2021, https://doi.org/10.1029/2020gl092293) report trends in daily precipitation patterns over the last five decades in the western United States, focusing on meteorological drought. They report that dry intervals (calculated at the annual or seasonal level) have increased across much of the southwestern U.S., with statistical assessment suggesting the results are statistically robust. However, Zhang et al. (2021, https://doi.org/10.1029/2020gl092293) preprocess their annual (or seasonal) averages to compute 5‐year moving window averages before using established statistical techniques for trend analysis that assume independence about some fixed trend. Here we show that the moving window preprocessing violates that independence assumption and inflates the statistical significance of their trend estimates. This raises questions about the robustness of their results. We conclude by discussing the difficulty of adjusting for spatial structure when assessing time trends in a regional context.

Millennial and suborbital-scale El Niño/Southern Oscillation control of climate variability in southern China over the past 70 ka

Hydroclimatic changes in East Asia on suborbital and millennial time scales have been shown to be highly uncertain. The El Niño-Southern Oscillation (ENSO) activity plays a key role in precipitation in low-latitude East Asia on interannual and interdecadal time scales. However, there remained some ambiguity about their connection on millennial and suborbital time scales. This study comprehensively explored the multifaceted relationships between ENSO activities, suborbital and millennial-scale drought events, and hydroclimatic variations within the Huguangyan Maar Lake (HML) region during the past 70 ka. Four suborbital-scale dry and wet hydroclimatic phases interspersed with ten millennial-scale extreme dry intervals were revealed by the ratio of hematite and goethite (Hem/Goe). These stages and intervals unexpectedly coupled with the zonal sea surface temperature (ΔSST) of the tropical Pacific Ocean, underscored the complex spatial and temporal dynamics of ENSO impacts. We propose the “glacial-El Niño-arid” and “interglacial-La Niña-humid” hydroclimate patterns on the suborbital scale. While on the millennial-scale, La Niña-like fluctuations during the persistent cold period (16–40 ka) increased the frequency and intensity of droughts in low-latitude East Asia, which was in stark contrast to the wet climate in northern China. The dynamic relationship underpins a millennia-spanning La Niña-drought pattern, elucidating the intertwined nature of ENSO dynamics and hydroclimatic variability on both sub-orbital and millennial scales. The above findings can be attributed to changes in the location and intensity of the Western Pacific subtropical high (WPSH) over southern China induced by persistent mean ENSO-like states in the tropical Pacific. This also indicates that the hydroclimate in low-latitude East Asia is more sensitive to variations in tropical ENSO compared to northern China.

Holocene and late Pleistocene bioclimatic change inferred from δ13C of organic carbon in buried alluvial soils in the tallgrass prairie, northeastern Kansas

The tallgrass prairie of the Central Plains is one of the largest North American biomes, yet little is known about the history of late-Quaternary bioclimatic change in the region because settings that are favorable for the preservation of traditional paleoenvironmental proxies, such as pollen and plant macrofossils, are rare. However, the valleys of large streams contain thick soil-stratigraphic sequences that span the Holocene and terminal Pleistocene and are archives of other paleoenvironmental proxies. To better understand late-Quaternary bioclimatic change in the tallgrass prairie, we analyzed the stable carbon isotope (δ13C) composition of soil organic matter (SOM) preserved in buried soils in floodplain, terrace, and alluvial fan deposits in the Big Blue River valley of northeast Kansas. A combination of eight cores and three outcrops at six localities were investigated, and 27 radiocarbon ages provide a robust numerical chronology. Based on our analysis, the tallgrass prairie has experienced significant bioclimatic changes over the past 27,000 years. From the LGM to the beginning of the late Holocene (ca. 25,000–4500 cal yr BP), there is an overall increase in C4 plant contributions to SOM, suggesting general warming for that period. However, warming and C4 grass expansion occurred in a non-linear fashion, with minor variations in the abundance of C4 vs C3 plants reflecting either small fluctuations in temperatures during general warming trends or other environmental factors, such as landscape disturbance, periods of drought, or the seasonal distribution of precipitation. The δ13C record also suggests that a major warming event occurred in the region between ca. 3000–1300 cal yr BP, when the contribution of C4 biomass to SOM exceeded 95 %. This climatic event does not appear to be an anomaly, as multiple paleoenvironmental proxies indicate a brief but exceedingly warm and dry interval occurred from 3300 to 2800 cal yr BP.

The influence of tropical Atlantic sea-surface temperatures and the North Atlantic Subtropical High during the Maya Droughts

The frequency and duration of Late-Holocene hydrologic extremes in northern Guatemala were investigated using multiple sedimentological and geochemical proxies preserved in a sediment core collected from Lake Petén Itzá. A general trend of increasing aridity in the Maya Lowlands during the past 2000 years was punctuated by several multidecadal- to centennial-scale drought events recorded in the Petén Itzá sediments. In particular, the period spanning the Maya Terminal Classic Period and the Medieval Climate Anomaly (MCA), between 800 and 1300 CE, was marked by several extreme droughts and included the driest conditions of the past 2000 years between 950 and 1100 CE. Similarities between our data and other existing regional paleoclimate records suggest regional drying events during this time may have been driven by a common mechanism. Specifically, comparisons between these records and tropical Atlantic sea surface temperatures (SSTs) suggest that the dry intervals may have been driven by a westward expansion of the North Atlantic Subtropical High pressure system. This period was unique in the general agreement between regional proxy records, which are otherwise notably heterogeneous during the Late-Holocene. During the Little Ice Age (LIA; 1400–1800 CE) mean precipitation at Petén Itzá was further reduced, and multidecadal drying events were recorded between 1500–1530, 1600–1640, and 1770–1800 CE. However, regional hydroclimatic coherency was weaker during the LIA, suggesting that additional climatic mechanisms played a more important role in local-scale hydrology during that time.

Comparing petrophysical properties and pore network characteristics of carbonate reservoir rocks using micro X-ray tomography imaging and microfacies analyses

Carbonate rocks have complex pore structures as a result of sedimentological and diagenetic processes. We investigated the pore network of four carbonate rock samples originating from an oil well in Hungary. Two samples were from the productive part of the Sarmatian limestone, and the other two were from the dry interval. We employed X-ray computed tomography (micro-XCT) in combination with lab measurements and microfacies analysis. To achieve accurate X-ray image segmentation we investigated and compared several segmentation techniques, including entropy and clustering. We then employed the Naïve Bayes classifier and tenfold cross-validation to assess the accuracy of our results. Our study achieved high accuracy with the type-2 fuzzy entropy technique on various metrics, including precision and recall. The comparison between the measured helium porosity and image-derived porosity showed a close match. Micro-XCT measurements revealed connected pore structure in the productive interval, compared to isolated pores in the dry interval. Microfacies analyses indicated that both the rocks of the productive and dry intervals were deposited in a marine environment, but different diagenetic processes altered the sediment into productive and dry rocks, respectively. The diagenesis of the productive rocks occurred in a meteoric phreatic environment, where secondary pores were created (porosity enhancement). In contrast, the dry rocks underwent meteoric vadose and marine diagenesis, where all previously created pores were filled with cement (porosity destruction). Our study highlights the importance of accurately characterizing the pore network of carbonate rocks, which can aid in understanding reservoir properties and predicting fluid flow behavior.

Holocene humid periods of the Levant – evidence from Dead Sea lake-levels

Water availability in the Levant is predicted to decline due to global warming in the upcoming decades and is expected to substantially impact the region. Determining the long-term natural rainfall variability in this region is essential for understanding the regional hydroclimatic response to external climate forcings and for contextualizing future hydroclimate changes. The Dead Sea (DS), located in the southern Levant, is a closed-basin lake whose size varies as a function of water availability. Reconstructing DS lake-level variations through time provides a quantitative measure of the natural hydroclimate variability and can inform on the local hydroclimate response to changes in global climate. Here, we constructed an updated lake-level history of the Holocene DS by: 1) studying lake high-stands derived from a series of new cores collected in the DS southern basin, 2) re-dating of the two major Holocene high-stand exposures, and 3) compiling all previously published ages of Holocene DS lake-level markers (n = 296 radiocarbon ages). The results show that the early (10–6.1 kyr cal BP) and late Holocene (3.6–0 kyr cal BP) in the DS were predominantly wet albeit punctuated by dry intervals, whereas the middle Holocene (6.1–3.6 kyr cal BP) was most likely relatively dry. This pattern of two Holocene humid intervals is also evident in distillation records derived from Levant speleothem caves (which represent the integrated magnitude of rainout from the vapor source to the caves), indicating that rainfall intensity and total water availability were correlated throughout the Holocene. These two humid intervals occurred during high and low summer insolation conditions, suggesting that they were modulated by different climatic mechanisms. The predicted future drying in the Levant is of similar magnitude to the natural hydroclimate variability and thus, it is crucial to assess whether the anthropogenic drying is in- or out-of phase with the natural climate variability.

Drought variations in the southeastern Tibetan Plateau region since 1704 and their link to the Atlantic Multidecadal Oscillation

Understanding the long-term history of drought in the Tibetan Plateau region is important to improve understanding of drought frequency in response to future global warming. Although the Tibetan Plateau has become generally wetter recently, the southeastern part of the Tibetan Plateau has become drier since the 2000s. To place this drying trend in a historical context, we conducted tree-ring studies for Abies spectabilis and Tsuga dumosa at three sites in the southeastern Tibetan Plateau, and developed tree-ring width (TRW), earlywood width (EWW), and latewood width (LWW) chronologies to permit local drought reconstruction. Based on correlation between these tree-ring parameters and instrumental meteorological data, the EWW chronologies were identified as suitable variables for reconstructing the average April–July self-calibrating Palmer Drought Index (scPDSI). The reconstruction accounted for 45.86% of the variance in the instrumental record and allowed us to extend the drought record back to 1704 CE. Based on this new dataset, the driest interval was from 1907 to 1919 CE during which time agricultural production fell by about 70% according to written historical records, leading to severe famine. Our findings suggest that this early twentieth century drought was in phase with the previously known drought over the northern Daxing'an Mountains. However, the southeastern Tibetan Plateau drought occurred one decade earlier than the known widespread drought event in North China during the 1920s–1930s. We show that this spatial drought pattern may have been modulated by the Atlantic Multidecadal Oscillation.

Paleofire dynamics in response to climate change during late Miocene derived from microcharcoal records in the Weihe Basin

The Weihe Basin, situated in the central part of Shaanxi Province between the Qinling and Weibei Mountains, falls under the influence of the Asian monsoon system. The basin's thick and continuous Cenozoic sedimentary layers offer a valuable repository for investigating environmental changes within a typical monsoon climate. Based on previous chronological research, our study delved into the microcharcoal concentration (MCC) of the samples extracted from Bahe Formation. This analysis aimed to reconstruct the paleo-fire and drought history during the late Miocene, shedding light on the region's evolutionary trajectory. Our findings unveil five distinct peaks in the microcharcoal record, occurring at approximately 9.9–9.7 million years ago (Ma), ∼9.5 Ma, ∼8.1 Ma, ∼7.6 Ma, and 7.4–7.2 Ma. These peaks signify high-frequency fire events, primarily taking place during periods of aridity. The combustion of broadleaved and coniferous trees was the predominant source of fuel for fires during 9.9–9.7 Ma, ∼9.5 Ma and ∼8.1 Ma, with elevated temperatures acting as the principal ignition catalyst. In contrast, the subsequent two fire events (∼7.6 Ma, and 7.4–7.2 Ma) coincided with drier climatic conditions, featuring xerophytic herbs s as the primary biomass. Drought emerged as the pivotal driving force behind these fire occurrences in this phase. The microcharcoal records of the Bahe Formation reveal a noteworthy pattern: the MCC during the latter two periods surpassed that of the initial three, indicating an escalated frequency of fires during dry intervals. This trend signifies a transition towards a dry and cold climate post ∼8.0 Ma. The expansion of grasslands and the occurrence of drought events since the late Miocene (∼8.0 Ma) can be attributed to the weakening of the Asian Monsoon. In summary, our investigation of microcharcoal concentration in the Bahe Formation provides valuable insights into the late Miocene paleo-fire and drought dynamics. By deciphering the interplay between vegetation, climate, and fire occurrences, our study contributes to a more comprehensive understanding of the environmental evolution within the Weihe Basin under the influence of the Asian monsoon system.

Long term evaluation of continence after complete primary bladder exstrophy repair

Continence after bladder exstrophy (BE) repair remains a major debatable challenge to pediatric urologists, together with the lack of standard definitions and long-term results in large series. We assessed the long-term urinary continence in 142 toilet-trained cases after one (1-) stage of complete primary repair of bladder exstrophy (CPRE) and consequent procedures to achieve this goal in a single tertiary referral center. The current retrospective study included 123 boys and 19 girls with BE that were repaired by (1-) stage CPRE. The Mean age at (BE) repair was 9.5±2.6 weeks. Complete penile disassembly (CPD) was used for epispadias repair in 42 (34.1%) and modified Cantwell-Ransley repair (MCR) was used in 81 (65.9%) boys. Bilateral anterior transverse innominate osteotomies (ATIO) were applied in all. Urinary continence was expressed in terms of the dry interval (DI). Continence procedures were afforded if CPRE failed to achieve DI≥3h (hrs.), those were in the form of endoscopic bladder neck injection (BNI), bladder neck reconstruction (BNR), and bladder neck closure (BNC) with catheterizable stoma. The mean age at follow up was 12.1±5.2 years. DI≥3h was gained in 23 (16.2%) after CPRE alone, while complementary post-CPRE continence procedures were required to reach this goal in the remaining patients. Deflux injection was reported in 10 (7%), CIC in 8 (5.6%), BNR in 32 (22.5), and BNC with catheterizable stoma alone in 37 (26.1%), or with Charleston pouch in 32 (22.5%). We think that ≥3h DI with voiding represents an appropriate definition of continence after BE repair. According to the results in the current series, we think that successful anatomical closure of BE is achievable, but the functional outcome in terms of continence and its evaluation is tricky. Results of continence were reported to change with age of the child, and it is difficult to evaluate both before toilet training age and long-term follow up. Long-term follow up of CPRE with bilateral ATIO alone or with BNI results in ≥3h DI in a few cases; BNR after CPRE can provide a good chance for continence; otherwise, BNC with catheterizable stoma is a valid option.

Extension of the Gardner exponential equation to represent the hydraulic conductivity curve: Inclusion of macropore flow effects

In soil hydraulics, it is crucial to establish an accurate representation of the relative hydraulic conductive curve (rHCC), K_r(h). This paper proposes a simple way to determine K_r(h), called the Modified Gardner Dual model (MGD), using a logarithmic extension of the classical Gardner exponential representation and including macropore flow effects. MGD has five parameters which are hydraulic constants clearly identified in the bilogarithmic representation of K_r(h). Two of them are related to the main inflection point coordinates of rHCC; from them, it is possible to determine the macroscopic capillary length of the infiltration theory. The model was tested in the suction interval 0 < h < 15,000 cm with a total of 249 soil samples from two databases, and employing a flexible representation of the Mualem-van Genuchten (MVG) equation as a reference. Using the RMSE statistics (with log base) to measure the fitting errors, we obtained a 31% reduction in errors (RMSE_MGD = 0.27, RMSE_MVG = 0.39). In 74% of the soils, including samples from the two databases, the reduction was 53% (RMSE_MGD = 0.19, RMSE_MVG = 0.40); the rHCC data fitting of this group was accurate over all the suction h intervals, with RMSE_MGD < 0.32 in each soil sample. In the remaining 26% of the samples, the quality of the MGD fitting degraded due mainly to the presence of multiple rHCC data inflection points. Therefore, in soils without this structural peculiarity, the proposed model revealed to be quite accurate in addition to being analytically simple. Another advantage of MGD is that its parameters depend mainly on the data with h around and lower than the main inflection suction value, which, in turn, never exceeded the 300-cm limit in this study. Hence, in soils that do not have multiple inflections, the extrapolations of the model in drier intervals (1000 cm < h < 15,000 cm) are reliable. The MGD parameter optimization software has been called KUNSAT. It is available in the Supplementary Material or from the corresponding author on request.

Effects of moderate drought extension on bacterial network structure in the rhizosphere soil of Leymus chinensis in semi-arid grasslands.

Grasslands are home to complex bacterial communities whose dynamic interactions play a crucial role in organic matter and nutrient cycling. However, there is limited understanding regarding the impact of changes in rainfall amount and the duration of dry intervals on bacterial interactions. To assess the impact of changes in precipitation volume and dry intervals on bacterial co-occurrence networks, we carried out precipitation manipulation experiments in the Eastern Eurasian Steppe of China. We found that alterations in precipitation and dry intervals did not significantly affect bacterial alpha and beta diversity. However, we observed significant changes in the co-occurrence network structure of bacteria in the rhizosphere ecosystem, with the 12-day dry interval showing the most notable reduction in the number of degrees, edges, and clustering coefficient. Additionally, the study identified putative keystone taxa and observed that the moderately prolonged dry intervals between precipitation events had a major effect on the robustness of bacterial networks. The complexity and stability of the network were found to be positively correlated, and were primarily influenced by soil water content, phosphorous, and aboveground biomass, followed by available phosphorus (AP) and total biomass. These findings have the potential to enhance our comprehension of how bacterial co-occurrence pattern react to variations in dry intervals, by regulating their interactions in water-limited ecosystems. This, in turn, could aid in predicting the impact of precipitation regime alterations on ecosystem nutrient cycling, as well as the feedback between ecosystem processes and global climate change.