Wet Climatic Conditions Research Articles

Hydroclimate modulation of central-eastern Mexico by the North Atlantic subtropical high since the little ice age

We reconstructed the hydroclimate of central-eastern Mexico over the last 700 common era (CE) based on inferences from multi-proxies from a stalagmite (K-Inc) collected at Karmidas cave, eastern México. Projections on hydroclimate variability in Mexico raise concerns about possible future occurrences of severe droughts and seasonal water balance fluctuations related to increased global temperatures caused by anthropogenic climate change (Murray-Tortarolo, 2021). The eastern region influences the production and supply of food to Mexico. Simulations of past climates, validated by paleoclimate records, yield valuable perspectives on climate change and enhance our understanding of future projections. However, the paucity of paleoclimatic records hinders understanding past hydroclimatic variations and their climatic mechanisms in eastern Mexico. Our record covers the Little Ice Age (LIA) through the Historical Interval (HI), a crucial period for understanding the climate repercussions spanning the transition from Earth's climatic history to the post-industrial era. The reduced intensity of the North Atlantic Subtropical High (NASH) during the LIA enabled a prominent negative phase of NAO-like variability from 1600 CE until the end of LIA. Consequently, preferent meridional airflow within the continent fosters the encounter of moisture-laden intrusions with the increased frequency of cold surges as the occurrence of frontal rain in eastern Mexico, impairing the amount effect on the K-Inc δ18O record. However, after the artificial opening of the cave in 1910 CE, the δ18O records of K-Inc began to exhibit a ∼20-year oscillatory periodicity. In this context, the trace elements of K-Inc help elucidate the climatic conditions that governed the precipitation regime during the investigated period. The visual alignment between the zonal sea surface temperature (SST) variability in the eastern equatorial Pacific (EEP) and the trace elements (Sr/Ca and Ba/Ca) of K-Inc reveals their relationship. Warm zonal SST in the EEP appears to be associated with changes in the length of the winter and summer seasons in eastern Mexico during the LIA. In contrast, over the HI, the trace elements of K-Inc show an anti-phase response to Warm zonal SST in the EEP, denoting wetter climate conditions at the vicinities of Karmidas Cave. This configuration led to questioning the influence of SST zonal variability in the EEP during the HI, which was probably masked by more relevant climate forcing. Our findings enabled us to draw climate scenarios by addressing the main climate drivers in our records.

Drivers of carbon stabilization and sequestration in Brazil’s black soils

Climate and land use are recognized as two of the main drivers of changes in soil organic carbon (SOC) on a global scale. Both factors play an important role in understanding SOC sequestration and mitigation of climate change. Particularly important, black soils are mineral soils with high SOC contents and high natural fertility and play an important role in national and global food and climate security. Here, we used a database of 90 black soils in Brazil − under different climate and land use conditions across the country − to test the hypothesis that C stock is richer in wetter climate conditions and that agricultural land use reduces C stock and the percentage of carbon saturation (PCS%). Climate data were obtained from the National Oceanic Atmospheric Administration (NOAA) and used to classify Thornthwaite’s climate. The land use information was obtained in the MapBiomas platform and was grouped into three major types: cropland, pasture, and native vegetation. The nonparametric Kruskal-Wallis test showed no differences for C stock, C/N ratio, and PCS% for both land use and climate. The low C/N ratio and the strong correlation between Ca2+, CEC, clay, and SOC suggest that organo-mineral interactions − which are stronger in soils with high-activity clays (e.g., Chernozems, Kastanozems, and Phaeozems) − promotes greater stabilization of the SOC and its long-term persistence and, thus being less sensitive to variations in climate and land use. Considering the total area of approximately 3.7 × 106 ha and the average value of C stock of 93.2 Mg/ha, the total SOC stored in Brazil’s black soils is in the order of 0.35 Gt, and the carbon stock stabilization potential is 0.25 Gt. Our results highlight the potential of Brazil’s black soils to promote carbon sequestration and climate change mitigation.

Combining tree-ring growth and carbon isotope data enhances the understanding of climate sensitivity and physiological responses for Chinese fir in a common garden

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) is one of China's most important tree species, and possible adverse factors affecting its growth and physiology is of particular concern for climate change adaptation. In this context, growth performance (BAI: basal area increment and MAXD: maximum density), climate sensitivity, and the relative contributions of climatic and physiological determinants to growth were evaluated across the 30 Chinese fir provenances using a combination of dendroclimatology and carbon isotope analysis (δ13C). Over the past 27 years, intrinsic water-use efficiency (iWUE) increased significantly by 12.71–33.56 %, while radial growth decreased (−63.38 % to −88.93 %). Strong growth decreases reflected increasing water stress due to climate warming, which was not offset by greater iWUE. A similar trend was observed in the theoretical gas exchange scenario as a response to increasing Ca as stomata opened and Ci increased proportionally to Ca. This study identified temperature and relative humidity as determinants of growth and physiology. However, meteorological factors (temperature, relative humidity, and sunshine hours) contributed much less to growth than physiological factors (iWUE). Variation in performance and climate sensitivity among populations significantly correlated with the mean annual temperature of the seed source origin. In general, seed sources from warmer and more humid climates in the center region grew faster and had higher iWUE. Provenances from drier climates had slower growth, higher wood density, and higher carbon isotope discrimination (Δ13C) compared to those from wetter climate conditions. Compared to provenances from cooler regions, the seed sources from warmer climates were less sensitive to temperature but more sensitive to sunshine hours for BAI and MAXD. These results contribute to a better understanding of the climate sensitivity and physiological responses of the Chinese fir provenances to long-term changing climate.

Tree growth decline to warm-wet conditions in boreal forests is linked to stand density

Warm-wet climatic conditions are widely regarded as conducive to remarkable tree growth, alleviating climatic pressures. However, the notable decline in tree growth observed in the southern edge of boreal forests has heightened concerns over the spatial-temporal dynamics of forest decline. Currently, attaining a comprehensive grasp of the underlying patterns and their propelling factors remains a formidable challenge. We collected tree ring samples from a network of 50 sites across the Greater Xing’an Mountains. These samples were subsequently grouped into two distinct clusters, designated as Groups A and B. The percentage change of growth (GC, %) and the proportion of declining sites were utilized to assess forest decline. The decline in tree growth within Larix gmelinii forests exhibits significant regional variation, accompanied by temporal fluctuations even within a given region. Group A exhibited a pronounced increase in frequency (59.26%) of occurrences and encountered more severe declines (21.65%) in tree growth subsequent to the 1990s, contrasting sharply with Group B, which observed lower frequencies (20.00%) and relatively less severe declines (21.02%) prior to the 1980s. The primary impetus underlying the opposite radial growth increments observed in Larix gmelinii trees from the interplay between their differential response to temperatures and wetter climatic conditions, which is significantly influenced by varying stand densities. In cold-dry conditions, low-density forests may experience soil water freezing, exacerbating drought conditions and thereby inhibiting tree growth, in Group A. Trees growth in high-density stands is enhanced under warm-wet conditions, in Group B. These results provide new insights into the variability at the southern edge of the boreal forest biome with different responses to density and climate.

Historical vegetation shifts in southeastern Amazonia: Unraveling ecotone dynamics in the Carajás region over the last ∼14000 cal yr BP

This study investigates the Pleistocene–Holocene transition in Serra Leste, a highly endangered southeastern Amazonian ecotone, with a focus on the lake-filling process, climate changes, and potential consequences to forest and savanna dynamics. The lake's development began at approximately 14000 cal yr BP, resulting from the collapse of the fractured lateritic crust. Sedimentation patterns and geochemical, palynological and micro-charcoal proxies reveal shifts in detrital input and redox conditions, forest/savanna areas, and local and regional fire events, indicating a highly dynamic environmental history. The evolution of the lake is characterized by initial deltaic lobe deposition and forest dominance, followed in the Middle Holocene by sedimentary gaps or reduced detrital input; woody vegetation dominance, with a notable shift toward a more open landscape; and savanna and semideciduous dry forest, accompanied by a decrease in ombrophilous forests. A resurgence in arboreal elements recorded in the Late Holocene indicates an expansion of ombrophilous forests under wetter climate conditions and the establishment of a more continuous forest matrix, with the presence of likely “hyperdominant” taxa. Frequent local fire events and the occurrence of temporarily correlated archeological sites in the Serra Leste region suggest the influence of ancient indigenous communities on vegetation changes during the Late Holocene.

Annual and seasonal mean daily discharge in natural and regulated rivers in Northern Finland: variability, trends, and links to climate teleconnections

ABSTRACT This study aimed to investigate long-term (1969–2023) variability and trends in annual mean daily discharge (AMDD) and seasonal mean daily discharge (SMDD) in 10 rivers throughout Northern Finland in connection to climate teleconnections. The lowest AMDDs were mostly recorded during the first 12 years (1969–1980) of our study period, while the highest ones were during the last 12 years (2012–2023). Significant trends in AMDD were found only in three natural rivers of Tornionjoki, Simojoki, and Kuivajoki during 1969–2023. Such variations and trends in AMDD were most significantly associated with the Scandinavia (SCA) pattern, which is also an influential climate teleconnection for annual precipitation anomalies across Northern Finland. The highest (lowest) SMDDs were experienced in spring (winter). Only increasing trends in SMDD were statistically significant (p < 0.05). Such substantial increases in SMDDs were detected in winter, spring, and summer (autumn) in association with the Arctic Oscillation or AO and the North Atlantic Oscillation or NAO (East Atlantic/West Russia or EA/WR). Generally speaking, recent milder and wetter climatic conditions in association with strong positive AO and NAO (negative EA/WR) phases could increase SMDD for winter, spring, and summer (autumn) seasons. Hence, both AMDD and SMDD in rivers throughout Northern Finland were primarily influenced by precipitation.

Effect of Nixtamalization on Aflatoxins, Functional and Acceptability of Maize from Mulindi, Rwanda

Rwanda relies highly on maize for human food as well as for animal feed and industrial uses. However, high temperature and wet climate conditions in Rwanda favor the growth of fungi that may lead to mycotoxin contamination in maize and subsequent degradation of its quality. Therefore, this study aimed to assess the effect of nixtamalization on the aflatoxins, the functional and acceptability of maize grains from Mulindi, Rwanda. The maize samples were collected from the Mulindi market in Rwanda; representative samples were collected by the guidelines for sampling food for mycotoxin determination. Subsequently, the treated maize samples were dry-milled to produce fine flour, and the flour obtained was analyzed for swelling capacity, water absorption capacity, water solubility, acceptability, and aflatoxins, which were quantified by the HPLC method. The HPLC results showed that the highest total aflatoxin level in maize grains was 44.99 ppb. Cooking maize in water and calcium hydroxide of 1% resulted in a reduction of aflatoxin with degradation percentages of 25% and 88%, respectively. However, in all treatments, aflatoxins B1 and B2 were less reduced compared to aflatoxins G1 and G2. Cooking maize in pure water showed the lowest reduction of aflatoxin compared to the other treatments. However, cooking maize in water with 1% calcium hydroxide decreased aflatoxin to a higher percentage. Cooking maize in lime enhanced the swelling capacity, water absorption capacity, and water solubility of maize, as well as its acceptability. However, the nixtamalization process was observed to reduce aflatoxins levels in maize and improve the functional properties of maize, and therefore, its application could be encouraged for safe products in the market.

Coefficient Analysis of the Alluvial Fan Surface Geometry: A Methodological Approach to Applied Geomorphology

The alluvial fan is a depositional geomorphic surface at the foothills. Most of the alluvial fans in tropical regions are highly dynamic under wet climatic conditions and neotectonic environments. The fans of this region are covered with fertile top soils and deep forests. The soils attack people for agriculture in this region. Presently the continuously growing population pressure causes huge deforestation in these alluvial fan areas for cultivation which causes an accelerating rate of natural hazards like flash floods, landslides, and soil erosion that accelerate the dynamic nature of the fan surfaces. The coefficient analysis helps to understand the dynamic nature of the alluvial fan surface and thus helps to identify the hazard-prone area for planning purposes.

Lake level fluctuations and varve preservation – The sediment record from Lake Suminko (Poland) reflects European paleoclimatic changes

We present a reconstruction of Holocene lake-level fluctuations at Lake Suminko, a eutrophic hardwater lake in northern Poland. The lake contains annually laminated (varved) sediments, forming a unique archive of past hydroclimatic variability. Employing a combination of sedimentological and geochemical methods, we demonstrate that sediment core sections with well-preserved varves and lower Ca/Fe ratios correspond to periods of higher water levels associated with colder and wetter climatic conditions. We identify twelve periods of lake level high stands, consistent with other lake sediment records from western Poland and Europe, as well as with North Atlantic IRD events. Pollen data and geochemical proxies confirm negligible human impact on the lake during most of the Holocene, except for the last 500 years when accelerated soil erosion related to landscape opening and agricultural activities occurred. Therefore, we conclude that Holocene lake-level fluctuations at Lake Suminko are primarily controlled by climatic conditions regulating water availability and groundwater supplies to the lake. Our study also highlights the potential of varve preservation as a useful indicator of lake-level changes.

Relative decline in density of Northern Hemisphere tree species in warm and arid regions of their climate niches

Although climate change is expected to drive tree species toward colder and wetter regions of their distribution, broadscale empirical evidence is lacking. One possibility is that past and present human activities in forests obscure or alter the effects of climate. Here, using data from more than two million monitored trees from 73 widely distributed species, we quantify changes in tree species density within their climatic niches across Northern Hemisphere forests. We observe a reduction in mean density across species, coupled with a tendency toward increasing tree size. However, the direction and magnitude of changes in density exhibit considerable variability between species, influenced by stand development that results from previous stand-level disturbances. Remarkably, when accounting for stand development, our findings show a significant change in density toward cold and wet climatic conditions for 43% of the species, compared to only 14% of species significantly changing their density toward warm and arid conditions in both early- and late-development stands. The observed changes in climate-driven density showed no clear association with species traits related to drought tolerance, recruitment and dispersal capacity, or resource use, nor with the temperature or aridity affiliation of the species, leaving the underlying mechanism uncertain. Forest conservation policies and associated management strategies might want to consider anticipated long-term species range shifts alongside the integration of contemporary within-distribution density changes.

Caught in the Act: Incipient Speciation at the Southern Limit of Viburnum in the Central Andes.

A fundamental objective of evolutionary biology is to understand the origin of independently evolving species. Phylogenetic studies of species radiations rarely are able to document ongoing speciation; instead, modes of speciation, entailing geographic separation and/or ecological differentiation, are posited retrospectively. The Oreinotinus clade of Viburnum has radiated recently from north to south through the cloud forests of Mexico and Central America to the Central Andes. Our analyses support a hypothesis of incipient speciation in Oreinotinus at the southern edge of its geographic range, from central Peru to northern Argentina. Although several species and infraspecific taxa have been recognized in this area, multiple lines of evidence and analytical approaches (including analyses of phylogenetic relationships, genetic structure, leaf morphology, and climatic envelopes) favor the recognition of just a single species, V. seemenii. We show that what has previously been recognized as V. seemenii f. minor has recently occupied the drier Tucuman-Bolivian forest region from Samaipata in Bolivia to Salta in northern Argentina. Plants in these populations form a well-supported clade with a distinctive genetic signature and they have evolved smaller, narrower leaves. We interpret this as the beginning of a within-species divergence process that has elsewhere in the neotropics resulted repeatedly in Viburnum species with a particular set of leaf ecomorphs. Specifically, the southern populations are in the process of evolving the small, glabrous, and entire leaf ecomorph that has evolved in four other montane areas of endemism. As predicted based on our studies of leaf ecomorphs in Chiapas, Mexico, these southern populations experience generally drier conditions, with large diurnal temperature fluctuations. In a central portion of the range of V. seemenii, characterized by wetter climatic conditions, we also document what may be the initial differentiation of the leaf ecomorph with larger, pubescent, and toothy leaves. The emergence of these ecomorphs thus appears to be driven by adaptation to subtly different climatic conditions in separate geographic regions, as opposed to parapatric differentiation along elevational gradients as suggested by Viburnum species distributions in other parts of the neotropics.

Identification of the Campanian Ignimbrite in the Dead Sea and consequent time-transgressive hydroclimatic shifts in the Eastern Mediterranean.

Robust chronologies and time equivalent tephra markers are essential to better understand spatial palaeoenvironmental response to past abrupt climatic changes. Identification of well-dated and widely dispersed volcanic ash by tephra and cryptotephra (microscopic volcanic ash) provides time synchronous tie-points and strongly reduces chronological uncertainties. Here, we present the major, minor and trace element analyses of cryptotephra shards in the Dead Sea Deep Drilling sedimentary record (DSDDP 5017-1A) matching the Campanian Ignimbrite (CI). This geochemical identification expands the known dispersal range of the CI to the southeastern Mediterranean, over 2300km from the volcanic source. Due to the CI eruption occurring near-synchronous with North Atlantic ice surge of Heinrich Event 4 (HE4), this tephra provides insights into regional responses to large-scale climatic change in the Mediterranean. In the Dead Sea, the CI layer is associated with wetter climatic conditions. This contrasts with the contemporaneous occurrence of the CI deposition and dry conditions in the central and eastern Mediterranean suggesting a possible climate time-transgressive expansion of HE4. Our finding underscores the temporal and spatial complexity of regional climate responses and emphasises the importance of tephra as a time marker for studying large-scale climatic changes verses regional variations.

A 1 Ma sedimentary ancient DNA (sedaDNA) record of catchment vegetation changes and the developmental history of tropical Lake Towuti (Sulawesi, Indonesia).

Studying past ecosystems from ancient environmental DNA preserved in lake sediments (sedaDNA) is a rapidly expanding field. This research has mainly involved Holocene sediments from lakes in cool climates, with little known about the suitability of sedaDNA to reconstruct substantially older ecosystems in the warm tropics. Here, we report the successful recovery of chloroplast trnL (UAA) sequences (trnL-P6 loop) from the sedimentary record of Lake Towuti (Sulawesi, Indonesia) to elucidate changes in regional tropical vegetation assemblages during the lake's Late Quaternary paleodepositional history. After the stringent removal of contaminants and sequence artifacts, taxonomic assignment of the remaining genuine trnL-P6 reads showed that native nitrogen-fixing legumes, C3 grasses, and shallow wetland vegetation (Alocasia) were most strongly associated with >1-million-year-old (>1 Ma) peats and silts (114-98.8 m composite depth; mcd), which were deposited in a landscape of active river channels, shallow lakes, and peat-swamps. A statistically significant shift toward partly submerged shoreline vegetation that was likely rooted in anoxic muddy soils (i.e., peatland forest trees and wetland C3 grasses (Oryzaceae) and nutrient-demanding aquatic herbs (presumably Oenanthe javanica)) occurred at 76 mcd (~0.8 Ma), ~0.2 Ma after the transition into a permanent lake. This wetland vegetation was most strongly associated with diatom ooze (46-37 mcd), thought to be deposited during maximum nutrient availability and primary productivity. Herbs (Brassicaceae), trees/shrubs (Fabaceae and Theaceae), and C3 grasses correlated with inorganic parameters, indicating increased drainage of ultramafic sediments and laterite soils from the lakes' catchment, particularly at times of inferred drying. Downcore variability in trnL-P6 from tropical forest trees (Toona), shady ground cover herbs (Zingiberaceae), and tree orchids (Luisia) most strongly correlated with sediments of a predominantly felsic signature considered to be originating from the catchment of the Loeha River draining into Lake Towuti during wetter climate conditions. However, the co-correlation with dry climate-adapted trees (i.e., Castanopsis or Lithocarpus) plus C4 grasses suggests that increased precipitation seasonality also contributed to the increased drainage of felsic Loeha River sediments. This multiproxy approach shows that despite elevated insitu temperatures, tropical lake sediments potentially comprise long-term archives of ancient environmental DNA for reconstructing ecosystems, which warrants further exploration.

Towards evaluating the conditional probability of waterborne microbial risks associated with critical rainfall events following land application of animal waste — A focus on Irish pastures

ABSTRACT Modelling surface runoff and infiltration in an agricultural watershed is essential for understanding the nutrient cycle and water quality management. This research evaluates the critical rainfall events causing maximum surface runoff and infiltration. Empirical models such as Soil Conservation Service (SCS) curve number and Explicit Green-Ampt (EGA) were analysed for different soil hydraulic conditions and storm events with specific return periods. The present study forecasted the maximum daily rainfall and intensity as 113.6 mm and 19.9 cm h–1, respectively, considering a 100-year return period storm. The deterministic part of the model calculates the daily maximum surface runoff as 5.51 cm (from the SCS model). The EGA model revealed that the rainfall intensity of 0.143, 0.163, 0.175, 0.179, 0.181, 0.182, and 0.182 cm h−1 (duration of 24 h) was found critical for 1, 2, 5, 10, 25, 50, 100 year return period of the storm, respectively in different soil texture classes (sand, loamy sand, sandy loam, loam, silt loam, sandy clay loam, clay loam, silty clay soils). Exceptions imply for three occasions where the intensity of 0.407 cm h−1 and duration of 18 h produced maximum infiltration for silty clay loam, and intensity of 0.352 and 0.354 cm h−1 with 9 h rainfall (each) produced maximum infiltration for clay. The probabilistic model revealed that a daily storm event probability of 2.74 × 10–5 is associated with a simulated mean runoff depth of 0.69 cm and infiltration of 20.7 cm. Critical rainfall probabilities calculated in this study can be multiplied with the overall microbial/pollutant human health risk assessment framework to calculate conditional probability and better estimate microbial risk through the drinking water pathway. This study is very relevant for the wet climatic condition of Ireland, where most land use is pastures.

Fire–climate–human dynamics over the last 1800 years in the mesic Araucaria‐Nothofagus forests

AbstractAimFew palaeoenvironmental studies have been performed in Araucaria‐Nothofagus forests, which are highly vulnerable to ongoing threats from climate change and anthropogenic activities. The primary goal of this work is to reconstruct past environmental changes related to fire disturbances over the last 1800 years in Tolhuaca National Park (TNP), Chile.LocationTNP, Araucanian region (38.2°S; 71.8°W), Northwestern Patagonia, Chile.TaxaAraucaria araucana (Araucariaceae), Nothofagus spp. (Nothofagaceae).MethodsWe completed charcoal and pollen analyses to create two new palaeoecological records that span 1800 years. We compared the lake‐based reconstruction with the available local tree‐ring fire scar chronologies from the last 430 years. Using these data, we compute forest index changes, biomass burning trends and compare with estimates of archaeological radiocarbon density. We place our inferences with context of published regional palaeoclimatic proxies from the Patagonian‐Andean region.ResultsOur results showed that fire activity was higher than present between 200 and 1500 CE, with peaks around 200–400 CE and 1100–1500 CE. Periods with high fire activity are associated with reduced forest cover, as Araucaria declined when mixed‐severity fire regime occurred for extended periods. Pollen assemblages suggested a shift from dry to wet climate conditions at 1500 CE, and from 1750 CE onward, the arrival of exotic species reflected the land‐use changes related to forest clearance and transhumance practices.Main ConclusionsThe palaeoenvironmental reconstructions showed changes in vegetation, fire and climate over the past 1800 years in TNP. Wildfires have been the main disturbance process modifying the vegetation structure in the Araucaria and Nothofagus forests. Since 1750 CE intensive post‐Hispanic land‐use changes (forest clearances by fire and logging) took place in the study area, reducing the native vegetation cover. Climate variability, modulated by SAM‐like and ENSO‐like conditions, influenced the fire activity (availability and flammability of fuels), concomitantly with high archaeological density. The recent (after 2000 CE) increase of catastrophic wildfires may negatively affect the conservation strategies of Araucaria‐Nothofagus forests.

Life cycle assessment and pavement performance of recycled aggregates in road construction

Integrating environmental goals in the construction of infrastructure has attracted great attention over the past two decades. The use of construction and demolished waste materials (C&D) as a base layer for pavement structures gained popularity as a sustainable alternative to virgin aggregates (VA). An experimental testing program was designed to investigate several recycled materials as a potential replacement to VA in flexible pavements base layer. The testing program included routine tests, matric suction, static, and repeated load triaxial tests to measure the general engineering properties and evaluate the material performance under static and cyclic loading. The results of the laboratory testing program were employed to predict the pavement performance utilizing different combinations of C&D waste as a base layer for flexible pavement structures using the AASHTOWare Pavement ME Design at different climate conditions. The sustainability of using C&D material as a partial or full replacement of VA base material in pavement construction was evaluated by using the life cycle assessment (LCA) approach. The results showed that all the C&D materials yielded a much thinner base layer compared to the natural VA achieving the same pavement performance. Moreover, the reduction in the thickness is more significant in cold and wet climatic conditions rather than the hot and dry climatic conditions. LCA results revealed that the VA base layer had the highest environmental impact on all tested categories. VA materials, used as a base layer, show 65% higher global warming potential compared to C&D materials as a base layer in all climatic conditions.

Exploring the food-energy-water nexus in coupled natural-human systems under climate change with a fully integrated agent-based modeling framework

Managing water resources to meet increasing energy and food demands while maintaining environmental sustainability under climate change is a major challenge, especially when this nexus occurred in a coupled natural–human system (CNHS), where heterogeneous human activities affect the natural hydrologic cycle and vice versa. The relevant research has been limited by the lack of models that can effectively integrate human dynamics and hydrologic conditions with spatial details to examine co-evolutionary systems. To address this challenge, this paper develops a modeling framework that integrates an agent-based model (ABM; human behavior model) into a large-scale, process-based distributed hydrologic model to simulate human decisions endogenously in the hydrologic cycle. We then apply the Decision Scaling approach, an ex-post scenario analysis method, with our integrated model to study the bidirectional feedback of the CNHS under future changing climate conditions. With the Columbia River Basin (CRB) selected as the case study area, the calibration results show that the integrated model can simultaneously capture the historical irrigated water consumption and streamflow dynamics. Modeling results show that the trade-off between irrigated water consumption, hydropower generation, and streamflow will become more pronounced under hotter and wetter climate conditions at both the entire basin and regional (states and provinces) levels. Special attention should be given to “temperature thresholds” of different regions when the trade-off pattern started. The trade-off results can potentially inform the Columbia River Treaty renegotiation and provide insights for long-term water management policies.

Potential of a Charcoal Evaporative Cooling Chamber for Extending the Shelf Life of Vegetables


 
 
 There are wide varieties of vegetables in Sri Lanka. The ambient temperature and relative humidity have an impact on rate of vegetables deteriorate. Evaporative cooling is a well-known, cost- effective way to reduce postharvest lost in order to lower the temperature and increase the relative humidity. This research was done to create a charcoal cooling chamber for increase the shelf life of vegetables combining polythene packaging and active packaging additives. The study was carried out in wet zone, Sri Lanka with a sizable chamber made of coconut shell charcoal. A rectangular box made of chicken wire with a 1 m3 capacity serves as the evaporative cooling chamber. It made of chicken wire mesh with a hardwood frame. The walls filled with 50 mm thick coconut shell charcoal and a water outflow 8.33 ml/min for wetting the walls. Vegetable samples without any treatment were placed in the charcoal chamber along with vegetables wrapped in sealed polyethylene (gauge 300) with and without active packing components. With a control sample held in ambient settings, the treatments were put to the test four times over the course of nine days. Both unloading and loading situations were used to evaluate the performance of chamber. Temperature drops of 4° C on average and 2.07° C on average, respectively, were seen in dry and wet climate conditions. 92.49% on average was the cooling efficiency. Sealed polyethylene bags without active packaging components were found to be the best treatment when taking into account physiological weight loss and sensory tests. When compared to the control group on days 3, 6 and 9 physiological weight loss was considerably (P<0.05) less in the sealed polyethylene bags without active packing components. When compared to the control sample total soluble solid content less in sealed polythene bag. The sensory evaluation for the treatments inside the chamber was more acceptable than for the control. Vegetables can store fresh for up to three days in evaporative cooling chamber without packaging. These chambers can install vegetable stalls on the side of the roads in Sri Lanka for temporary purposes.
 Keywords: Charcoal, Evaporation, Shelf-life, Temperature, Vegetables
 
 

Goethite in the Red Clay sequences on the western Chinese Loess Plateau and its responses to the middle Miocene Climate Transition

The middle Miocene Climate Transition (MMCT, ca. 14 Ma), with a sharp drop in temperature, is a key transition period in the Earth’s climatic and biotic evolution. However, our knowledge of how arid-monsoon environments were coupled during the middle Miocene Climate transition remains limited, due to the lack of robust proxies from well-dated sedimentary sequences covering the MMCT in monsoon areas. Goethite is an abundant iron oxide in soils, which is sensitive to persistent wet and cold environments. However, aluminium (Al) substitution is ubiquitous in the pedogenic process, and the Al substitution for goethite in the Red Clay sequence is unclear. In this study, we combined the rock magnetic and DRS methods to assess the Al substitution level of goethite and quantify the goethite content in the Zhuanglang (ZL) Red Clay deposits from the western Chinese Loess Plateau. Our results show that Al substitution in the ZL Red Clay sequence is relatively stable, facilitating the quantification of goethite using this approach. Goethite content displays an increasing trend from approximately 0.2% at 18 Ma to 0.5% at 14 Ma, and then gradually decreased towards the late Miocene in the ZL Red Clay deposits. The maximum goethite production at around 14 Ma indicates a cold and wet climate condition during MMCO at this location. Together with other palaeoenvironmental proxies of this sequences and other sedimentary sequences in the Tianshui Basin, we suggest that climate conditions during the MMCT in the monsoonal western CLP were relatively cold and wet, which was different from the cold and dry climate in the central Asian. Global cooling and the uplift of the Tibetan Plateau might be predominantly responsible for the cold and wet climate during the MMCT.

Data‐driven modeling to enhance municipal water demand estimates in response to dynamic climate conditions

AbstractAltered precipitation and temperature patterns from a changing climate will affect supply, demand, and overall municipal water system operations throughout the arid western U.S. While supply forecasts leverage hydrological models to connect climate influences with surface water availability, demand forecasts typically estimate water use independent of climate and other externalities. Stemming from an increased focus on seasonal water demand management, we use the Salt Lake City, Utah municipal water system as a test bed to assess model accuracy versus complexity trade‐offs between simple climate‐independent econometric‐based models and complex climate‐sensitive data‐driven models to average to extreme wet and dry climate conditions—representative of a new climate normal. The climate‐independent model displayed low performance during extreme dry conditions with predictions exceeding 90% and 40% of the observed monthly and seasonal volumetric demands, respectively, which we attribute to insufficient model complexity. The climate‐sensitive models displayed greater accuracy in all conditions, with an ordinary least squares model demonstrating a measurable reduction in prediction bias (3.4% vs. −27.3%) and RMSE (74.0 lpcd vs. 294 lpcd) compared to the climate‐independent model. The climate‐sensitive workflow increased model accuracy and characterized climate‐demand interactions, demonstrating a novel tool to enhance water system management.