Arid Conditions Research Articles

Chemical degradation of agricultural soil under arid conditions by the accumulation of potentially toxic elements and salts

This study evaluates agricultural soil degradation by accumulation rates of chemical species and salinity/sodicity, their distribution, and the degree of contamination. Soil samples were collected from farmlands with intensive production system in the northern part of the Jiménez-Camargo aquifer, Chihuahua, Mexico. The physicochemical parameters and the chemical species were obtained based on Mexican regulations and UV–Vis spectrophotometry. The soil degradation was assessed using contamination-degree and soil-quality indices. A log-transformation (clr) of data facilitated cluster multivariate and related spatial distribution analysis. Chemical properties were found grouped within geogenic elements and salts. The results showed an alkaline pH with a wide range of ECe of 0.24 to 4.91 dS m−1. About 72% of the agricultural land showed a high sodicity/salinity degree, contributing to soil damage in the root zone of crops. Soil quality also is negatively affected by As, P, S, as well as salinity/sodicity, contributing to agri-environmental vulnerability of these farmlands. Hence, intensive agricultural land use contributes to severe ecological consequences such as groundwater depletion and water-quality degradation, as well as salinity/sodicity of soil, increased irrigation demand to flush salts from the soil zone, and enhancement of potentially toxic elements in soil-water-crops. In conclusion, monitoring these lands and source-water management are needed to mitigate soil-water degradation combined with agri-environmental policies through sustainability strategies that control supply and demand of land and water. The indices used here provide the metrics needed to help monitor and assess these changes for decision makers guiding sustainability and food security.

Dryland Endolithic Chroococcidiopsis andTemperate Fresh Water Synechocystis Have Distinct Membrane Lipid andPhotosynthesis Acclimation Strategies upon Desiccation andTemperature Increase.

An effect of climate change is the expansion of drylands in temperate regions, predicted to affect microbial biodiversity. Since photosynthetic organisms are at the base of ecosystem's trophic networks, we compared an endolithic desiccation-tolerant Chroococcidiopsis cyanobacteria isolated from gypsum rocks in the Atacama Desert with a freshwater desiccation-sensitive Synechocystis. We sought whether some acclimation traits in response to desiccation and temperature variations were shared, to evaluate the potential of temperate species to possibly become resilient to future arid conditions. When temperature varies, Synechocystis tunes the acyl composition of its lipids, via a homeoviscous acclimation mechanism known to adjust membrane fluidity, whereas no such change occurs in Chroococcidiopsis. Vice versa, a combined study of photosynthesis and pigment content shows that Chroococcidiopsis remodels its photosynthesis components and keeps an optimal photosynthetic capacity at all temperatures, whereas Synechocystis is unable to such adjustment. Upon desiccation on a gypsum surface, Synechocystis is rapidly unable to revive, whereas Chroococcidiopsis is capable to recover after three weeks. Using X-ray diffraction, we found no evidence that Chroococcidiopsis could use water extracted from gypsum crystals in such conditions as a surrogate for missing water. The sulfolipid sulfoquinovosyldiacylglycerol becomes the prominent membrane lipid in both dehydrated cyanobacteria, highlighting an overlooked function for this lipid. Chroococcidiopsis keeps a minimal level of monogalactosyldiacylglycerol, which may be essential for the recovery process. Results support that two independent adaptation strategies have evolved in these species to cope with temperature and desiccation increase and suggest some possible scenarios for microbial biodiversity change triggered by climate change.

Off-Season and Quality Production of Watermelon by Modifying Micro-Climate under Hot Arid Conditions

Off-Season and Quality Production of Watermelon by Modifying Micro-Climate under Hot Arid Conditions

Enhancement of Condenser Performance in Vapor Absorption Refrigeration Systems Operating in Arid Climatic Zones—Selection of Best Option

Generators and condensers are the two vital equipment items that determine the output of vapor absorption refrigeration systems. Arid weather conditions produce a significant reduction in the performance of the vapor absorption refrigeration cycle due to low condenser heat dissipation despite high generator temperatures. Although numerous studies on condenser cooling methods in vapor compression systems have been reported in the literature, solar-operated vapor absorption systems have not been studied. Limitations in generator temperatures of solar-operated vapor absorption systems necessitate a focused study in this area. This study makes the selection of the best choice for condenser cooling from among four different condenser cooling methods which have an impact on the performance of the vapor absorption refrigeration system for effective cooling using solar energy. A solar vapor absorption refrigeration system working with low-grade heat using a compound parabolic collector is considered in this study. Analysis of a vapor absorption refrigeration system for cooling in arid weather conditions is carried out using different condenser cooling methods with Engineering Equation Solver. Initially, the model used in the study is compared with a similar study reported in the literature. Techniques considered are air, water, evaporative, and hybrid cooling techniques. The performance of the vapor absorption cooling system was analyzed using experimental values of a solar compound parabolic collector obtained from real-time measurements for simulating the model. Results show that water cooling can provide suitable condenser cooling and improve the coefficient of performance of the solar vapor absorption refrigeration system using the solar collector. The water-cooled condenser has 1.9%, 3.3%, and 2.1% higher COP when compared to air-cooled condensers for spring, summer, and autumn seasons respectively, whereas the water-cooled condenser cooling recorded 6%, 14%, and 8% higher COP relative to the evaporative cooling method. Cost comparison showed maximum cost for water-cooled condensers and minimum cost for hybrid-cooled condensers. The effect of each cooling method on the environment is discussed.

Developing a sustainable water conservation strategy for Saudi Arabian cities

Water scarcity is a global issue posing significant challenges for sustainable water management. Saudi Arabia, due to its arid conditions, limited freshwater resources, and high evapotranspiration rates, faces water scarcity. Factors such as rapid population growth, urban expansion, industrial development, and unsustainable water management practices contribute to increased municipal water demand and per capita water consumption. This trend is evident in the Jubail Industrial City (JIC), the largest industrial city in the Middle East. Although JIC heavily relies on desalination and groundwater extraction to meet growing water needs, it lacks a strategic vision for water conservation. The objective of this paper is to identify the causes of water scarcity, assess the sustainability of current water management practices, and develop a sustainable water conservation strategy using JIC as a case study. The study adopts a mixed-method approach, involving a comprehensive review of literature and official documents, along with an analysis of successful case studies of water conservation practices in arid regions worldwide. The proposed strategy encompasses demand management, adoption of water-efficient technologies, water reuse and recycling, public awareness and education, and policy and governance frameworks. Strategic water conservation, optimization and reuse hold significant relevance to industry settings. The study’s findings can contribute to the enhancement of the municipal water supply sector and support decision-makers in achieving the sustainable water resource management goals outlined in Saudi Vision 2030.

AGROECONOMIC ASSESSMENT OF THE INFLUENCE OF SOWING METHODS AND SOWING RATES OF SAFLORO DYE SEEDS IN THE VOLGOGRAD REGION

Background. Safflower belongs to the category of insurance oilseeds, it is able to grow and form a seed crop for vegetable oils in extremely arid conditions. The production of safflower seeds is associated with extreme conditions, and therefore it is necessary to clarify in the arid climate of the Volgograd region in the zone of light chestnut soils the optimal seed sowing rate and an effective method of sowing it.
 Purpose. To study and determine the methods of sowing safflower seeds and the optimal sowing rates in agricultural landscapes in the zone of light-chestnut soils, the dry steppe of the Nizhnevolzhsky region to obtain high-quality seeds.
 Materials and methods. A single-factor field experiment was laid in 2022, in the steppe zone with a hydrothermal coefficient of 0.6-0.4. On the site for obtaining seeds, safflower was sown according to its predecessor - black fallow. Since autumn, the main tillage was carried out - disking, in the spring, spring harrowing in two tracks, followed by pre-sowing cultivation. The cultivars of dyeing safflower Aleksandrit, Volgogradsky 15 were sown, the originator of which is the Federal Scientific Center of Agroecology of the Russian Academy of Sciences. The repetition in the experiment is threefold, the variants are continuous. All repetitions in the experiment are placed in one field. The area of the experimental plot is 180 m2. The weather conditions during the period of formation of the safflower crop are characterized as dry, HTC 0.6, and the reserve of productive moisture during the sowing period in the meter layer was 12.72 mm. placement of options is systematic, sequential, in blocks in one tier
 Results. The conducted studies made it possible to determine that the highest yield of safflower was obtained from the Alexandrite variety of 1.22 t/ha in sowing with row spacing, a width of 15 cm and a seeding rate of 30 kg/ha and a profitability of producing high-quality seeds of 238.9%.
 Conclusion. Under the conditions of light chestnut soils in the dry steppe of the Volgograd region, it is advisable to sow safflower between rows, the width of which is 15 cm, and the optimal seeding rate is 30 kg/ha, while the economic benefit of seed production will be up to 238.9%.

COMPARATIVE ASSESSMENT OF PEARL MILLET GENOTYPES UNDER ARID CONDITIONS OF SOUTHEAST KAZAKHSTAN

A comparative assessment of 14 pearl millet genotypes transpired for growth and yield traits under arid conditions of Southeast Kazakhstan. In this study, the green and dry plant biomass and grain yield of 14 pearl millet genotypes’ assessment ensued under rainfed conditions in Southeast Kazakhstan. For green biomass yield, the three pearl millet genotypes Bair Bajsa, HHVBC tall, and J-6 performed better and were high yielders ranging from 39.07 to 39.94 t/ha. The accumulation of dry biomass (as hay) was different and varied widely from 3.17 to 17.36 t/ha; however, the maximum dry biomass appeared in the genotype HHVBC tall. Genotype HHVBC tall was leading for green and dry plant biomass formation and has the potential for grain yield under rainfed conditions of Southeast Kazakhstan. Drought always negatively impacted the production of fodder and grains; however, genotype HHVBC tall assures a stable plant biomass and seed production under arid conditions. In dry Southeast Kazakhstan, pearl millet, a drought-resistant crop, is a highly productive, valuable fodder and grain crop based on quality yields of biomass and grains. Subject to the cultivation technology and according to weather conditions, on average, the pearl millet genotypes form a green mass biomass yield of 40 t/ha and grain yield of 2.2 t/ha under rainfed conditions of Southeast Kazakhstan. For cultivation in the Republic, it is necessary to expand pearl millet as an annual crop, most adapted to extreme agroecological conditions.

Evaluation of safflower varieties for productivity and quality in the arid conditions of the Northern Caspian region

In a dry continental climate, safflower has an undeniable advantage over grains and oilseeds due to its morphological structure. The main advantage of this crop is that it is capable of extracting water from deep layers of soil with its developed root system, and due to the structural features of the vegetative mass, it can use it economically, while forming stable yields. Therefore, the search for promising varieties for the selection of new varieties, especially in the arid conditions of the Astrakhan region, continues to be relevant. Over the course of three years (2019-2021), there were studied 28 collection varieties of safflower of various ecological and geographical origin from the Federal Research Center N. I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR). During the study period, 12 varieties were identified from the collection under study based on the yield and a number of economically valuable traits for further use in breeding work. The productivity of the selected samples of the studied collection varied greatly, depending on the conditions of the year and on average exceeded the standard variety Astrakhansky 747 by 0.08...0.23 t/ha. At the same time, the highest yield of the selected samples was from Tajikistan (619 Tsam-buli, 618 Shahalli-260) and Kazakhstan (620 Shirkas, 622 Center 70) – 0.43...0.51 t/ha, that was 0.15…0.23 t/ha higher than the standard. According to the oil content in the seeds (0.5...1.9 % higher than the standard) the following varieties were identified: 621 Talan (Kazakhstan) – 30.3 %, 584 Sinaloa-90 (Mexico) – 30.3 %, 619 Tsambuli (Tajikistan) – 29.4 %, 609 Akmai (Kazakhstan) – 29.1 %. The development of new varieties based on selected samples will allow to obtain stable yields in extremely arid conditions of the region.

Modeling fuel moisture dynamics under climate change in Spain’s forests

BackgroundCurrent assessments of the effects of climate change on future wildfire risk are based on either empirical approaches or fire weather indices. No study has yet used process-based models over national scales to understand how and where will increases in climate aridity affect the likelihood of fire activity through changes in the moisture content of live (LFMC) and of dead (DFMC) fuels. Here, we used process-based models to forecast changes in LFMC and DFMC under the 21st century climatic conditions projected from moderate and high greenhouse gas emission scenarios (RCP4.5 and RCP8.5). Predictions were performed across broad productivity gradients in peninsular Spain to understand how productivity mediates the effects of climate change on fuel moisture dynamics.ResultsLFMC and DFMC were predicted to decline under the climatic conditions projected for the coming decades. Increases in the annual frequency of days with fuel moisture content below wildfire occurrence thresholds were predicted to extend fire season lengths by 20 days under RCP4.5 and by 50 days under RCP8.5. The effects of climate change on LFMC and DFMC varied linearly and negatively with productivity (stronger fuel moisture decreases in least productive environments). Although we observed a significant mitigation effect from rising CO2 (via increases in water-use efficiency), it was not enough to offset LFMC declining trends induced by increased temperature and aridity.ConclusionsWe predicted that the warmer and more arid climatic conditions projected for the 21st century will lead to generalized declines in fuel moisture, lengthening fire seasons, and increasing wildfire danger. The use of process-based models to forecast LFMC dynamics allowed the consideration of plant species capabilities to buffer climate change impacts. Significant increases in the fire season length predicted in the most productive environments, currently with large fire return intervals, would pose an increase of fire danger in major Spanish carbon sinks. Finally, the CO2 mitigation effect would not be enough to offset climate change-driven declines in seasonal LFMC levels.

Isolation and Identification of Bacteria from Three Geothermal Sites of the Atacama Desert and Their Plant-Beneficial Characteristics.

The Region of Arica and Parinacota (Atacama Desert) offers several unexplored remote sites with unique characteristics that would allow for the formulation of new bioproducts for agriculture. Among them, Jurasi Hot Springs, Polloquere Hot Springs, and Amuyo Lagoons represent a group of open pools fed by thermal water springing from the mountains. Their microbiomes remain unspecified, providing a unique opportunity to characterize the endemic community of these sites and develop new bioproducts for sustainable agriculture. Bacteria were isolated from the sediments of these geothermal sites and characterized by sequencing the 16S rRNA gene, microbiological characterization, and agricultural functional characterization. A total of 57 bacteria were isolated from three geothermal sites north of the Atacama Desert. The sequence analysis showed that the isolates belong to several bacterial genera, including Pantoea, Bacillus, and Pseudomonas, among others. The functional characterization revealed the presence of PGP traits, hydrolytic enzymes, and biocontrol activity against phytopathogenic fungi. These bacteria possess the potential to develop new biobased products for agriculture in arid conditions.

Aridity drives the variability of desert soil microbiomes across north-western China

Dryland covers >35 % of the terrestrial surface and the global extent of dryland increases due to the forecasted increase in aridity driven by climate change. Due to the climate change-driven aridity ecosystems, deserts provide one of the most hostile environments for microbial life and survival. Therefore, a detailed study was carried out to explore the deserts with different aridity levels (exposed to severe climate change) influence on microbial (bacteria, fungi, and protist) diversity patterns, assembly processes, and co-occurrence. The results revealed that the aridity (semi-arid, arid, and hyper-arid) patterns caused distinct changes in environmental heterogeneity in desert ecosystems. Similarly, microbial diversities were also reduced with increasing the aridity pattern, and it was found that environmental heterogeneity is highly involved in affecting microbial diversities under different ecological niches. Interestingly, it was found that certain microbes, including bacterial (Firmicutes), fungal (Sordariomycetes), and protistan (Ciliophora) abundance increased with increasing aridity levels, indicating that these microbes might possess the capability to tolerate the environmental stress conditions. Moreover, microbial community turnover analysis revealed that bacterial diversities followed homogenous selection, whereas fungi and protists were mostly driven by the dispersal limitation pattern. Co-occurrence network analysis showed that hyper-arid and arid conditions tightened the bacterial and fungal communities and had more positive associations compared to protistan. In conclusion, multiple lines of evidence were provided to shed light on the habitat specialization impact on microbial (bacteria, fungi, and protists) communities and composition under different desert ecosystems.

Impact of tillage and crop rotations on soil organic matter content in Northern Kazakhstan's chernozem soils: A 10-year study (2011-2021)

This extensive 10-year study conducted in Northern Kazakhstan investigates the intricate relationship between soil management techniques, crop rotations, and soil organic matter (SOM) content in Chernozem soils, an essential agricultural resource in the region. The experiments were established at the Karabalyk Agricultural Experimental Station, characterized by a arid continental climate. The study systematically examined the impact of two primary soil management techniques, conventional tillage (CT) and no-tillage (NT), in combination with various crop rotations. The crop rotations tested included grain-fallow rotations, fruit-exchange crop rotations, and an eight-field fruit-exchange crop rotation. The results provide valuable insights into the sustainable management of Chernozem soils in arid conditions, underscoring the role of crop rotation strategies in preserving SOM content. The findings reveal that among the crop rotations tested, the eight-field fruit-exchange crop rotation exhibited the most favorable outcomes for SOM preservation. This rotation helped maintain relatively stable SOM levels over the 10-year study period, contributing to soil health and fertility. In the context of the region's arid climate, the choice of soil management technique (CT or NT) had a limited impact on SOM content. The stability of SOM levels across diverse crop rotations and years highlights the dominant influence of crop management practices in this distinctive agricultural environment. This research serves as a valuable reference for tailored approaches to ensure soil health and organic matter preservation in the unique conditions of Northern Kazakhstan. It promotes the adoption of diversified crop rotations, with particular emphasis on the effectiveness of the eight-field fruit-exchange crop rotation, as a powerful strategy to mitigate organic matter loss, enhance soil quality, and optimize soil fertility in arid agricultural landscapes. The insights gained from this study are vital for sustainable land management in the region and underscore the importance of region-specific, holistic investigations to guide effective agricultural practices. The findings offer a solid foundation for the development of strategies that address soil health and safeguard the integrity of essential soil resources in these unique environments. The study conducted at the Karabalyk Agricultural Experimental Station in Northern Kazakhstan between 2011 and 2021 provides critical insights into the relationship between soil management techniques, crop rotations, and SOM content in Chernozem soils. The research suggests that diversified crop rotations, particularly the eight-field fruit-exchange crop rotation, represent a promising approach for mitigating organic matter loss and enhancing soil quality in arid regions.

Yield and grain quality of winter triticale varieties in the Volga region

Research on ordinary chernozem is presented to identify new promising varieties for modern technologies of growing winter triticale in arid conditions of the Volga region. In different weather conditions in the years (2019-2021), when testing 17 varieties of winter triticale, it was found out that the highest grain yield had the Krokha variety – 5.24 t/ha. The varieties Spika, Cornet, Consul, Valentine 90 were inferior to it by 0.23-0.34 t/ha (4.6-6.9%). According to the grain size, the 97-67T6P20 line stood out – 50.0 g, and the Zubr variety – 46.7 g, Capella – 46.3 g and Cornet – 46.0 g, respectively. The highest natural mass of 725-728 g/l had the varieties Capella and Consul, Lines 97-67T6 P 20. These varieties significantly exceeded Spika, Tornado and Valentine 90 by 23-43 g/l (3.3-6.3%). The protein content in the studied varieties varied from 12.7 to 15.5%, with the highest values in the Tornado feed direction variety – 15.5%. According to the complex of signs, the mass of 1000 grains (46-50 g), the nature of the grain (722-728 g/l) and the protein content (14.0-14.4%), the 97-67T6 P 20 line and the Capella variety were distinguished. Based on the data obtained on the yield and grain quality in the arid conditions of the Volga region, it is recommended to grow Krokha, Spika, Cornet, Consul, Valentine 90, and Gorka varieties.

Adaptive capabilities seedless grape varieties in a sharply continental climate

The article presents the results of the study of winter hardiness, drought resistance, heat resistance of seedless grape varieties at the initial stages of culture development in a sharply continental climate. The purpose of the research was to study and identify promising highly adaptive seedless grape varieties with a complex of economically valuable traits for cultivation in arid conditions of the North-Western Caspian Sea. The objectives of the research included: determination of the degree of winter hardiness of introduced grape varieties; assessment of drought resistance and heat resistance of the studied seedless varieties. The research was carried out in 2021...2022 at the vineyard of the Precaspian agrarian federal scientific center of the Russian academy of sciences, located in the Chernoyarsk district of the Astrakhan region. The object of research was 16 seedless grape varieties planted in 2020. The Radiant variety, zoned in the Lower Volga region, was adopted as the standard. It was found that, on average, over two years of research, the maximum degree of winter hardiness was characterized by varieties Golden, Lucia, Rose and Century with the safety of eyes after overwintering from 61.4 to 70.9 %. Varieties Radiant, Azak, Attica, Aphrodite, Ballet, Veles, Zolotce, Iskander, Nakhodka, Neptune, Tangra, Himrod, Jupiter they had an average degree of winter hardiness – from 43.1 to 58.1 %. The varieties Azak, Attica, Ballet, Zolotce, Iskander, Lucia, Neptune, Himrod, Jupiter were characterized by maximum resistance to stress factors of the summer period in the third year of vegetation. The most heat-resistant varieties were Zolotce, Century, Himrod, Jupiter, which lost the least amount of water during wilting (24.2...28.6 %) and, to a greater extent, restored hydration at saturation (60.2...87.9 %).

Pre-planting treatment of potato tubers with biopreparations in conditions of Central Yakutia

The results of the study of the influence of pre-planting treatment of tubers with biopreparations based on Bacillus subtilis bacterial strains on the growth, photosynthetic activity of plants, disease damage and yield of the Yakutyanka potato variety under the conditions of Central Yakutia are presented. The experiment scheme included control (tubers without treatment), treatment of the tubers before planting with the biofungicide Phytosporin-M and the suspension of an equal ratio of B. subtilis TNP-3 and B. subtilis TNP-5 bacterial strains isolated from permafrost soils of Yakutia. It was found that treatment of tubers before planting with biopreparations accelerated sprouting by 2-4 days, increased biomass and photosynthetic activity of the plants (by 6-19%), the number (11) and weight (48–57%) of tubers, reduced the damage of the plants by a complex of diseases by 1.8–2.9 times and increased the yield by 7.4–8.8 t/ha (54–64%). The share of biopreparation influence in the variability of economically valuable indicators and yield was shown to be 45–96%, weather conditions 1–38%, factor interaction 1–11%. Significant positive correlation of the yield, number and weight of the tubers with the height, number and weight of the plants, leaf area, photosynthetic potential (r = 0.81...0.98), and negative correlation with rhizoctonia disease, potato scab, and common mosaic (r = –0.80...–0.96) were revealed. There was an inverse relationship between disease prevalence and indices of plant growth and photosynthetic activity (r = –0.33...–0.96). Damage by potato scab and rhizoctonia disease increases 1.4–1.8 times in arid conditions, while blackleg, rugose and common mosaic damage decreases 1.6–2.5 times. Regression equations were calculated, which allow to predict leaf area, photosynthetic potential and yield by plant mass promptly and with high accuracy (R2 = 0.85...0.95). When the bush weight in the flowering phase increased by 100 g, the leaf area of the plants increased by 2.3 thousand m2/ha, photosynthetic potential during the growing season by 120 thousand m2 · day/ha, and the yield by 9.7 t/ha. The difference between actual and calculated values amounted to 2.7–4.7%.

A Continuous Centennial Late Glacial-Early Holocene (15-10 cal kyr BP) Palynological Record from the Iberian Pyrenees and Regional Comparisons.

This paper presents the first continuous (gap-free) Late Glacial-Early Holocene (LGEH) pollen record for the Iberian Pyrenees resolved at centennial resolution. The main aims are (i) to provide a standard chronostratigraphic correlation framework, (ii) to unravel the relationships between vegetation shifts, climatic changes and fire, and (iii) to obtain a regional picture of LGEH vegetation for the Pyrenees and the surrounding lowlands. Seven pollen assemblage zones were obtained and correlated with the stadial/interstadial phases of the Greenland ice cores that serve as a global reference. Several well-dated datums were also derived for keystone individual taxa that are useful for correlation purposes. Four vegetation types were identified, two of them corresponding to conifer and deciduous forests (Cf, Df) and two representing open vegetation types (O1, O2) with no modern analogs, dominated by Artemisia-Poaceae and Saxifraga-Cichorioideae, respectively. Forests dominated during interstadial phases (Bølling/Allerød and Early Holocene), whereas O1 dominated during stadials (Oldest Dryas and Younger Dryas), with O2 being important only in the first half of the Younger Dryas. The use of pollen-independent proxies for temperature and moisture allowed the reconstruction of paleoclimatic trends and the responses of the four vegetation types defined. The most relevant observation in this sense was the finding of wet climates during the Younger Dryas, which challenges the traditional view of arid conditions for this phase on the basis of former pollen records. Fire incidence was low until the Early Holocene, when regional fires were exacerbated, probably due to the combination of higher temperatures and forest biomass accumulation. These results are compared with the pollen records available for the whole Pyrenean range and the surrounding lowlands within the framework of elevational, climatic and biogeographical gradients. Some potential future developments are suggested on the basis of the obtained results, with an emphasis on the reconsideration of the LGEH spatiotemporal moisture patterns and the comparison of the Pyrenees with other European ranges from different climatic and biogeographical regions.

Fertilizer nitrogen use by cereal crops in arid conditions of Buryatia

The results of research in a long-term (1982–2021) stationary experiment to determine the coefficients of nitrogen use of mineral fertilizers by the crops of grain and fallow crop rotation in the conditions of the dry-steppe zone of Buryatia are presented. Chestnut loamy sand soil on the studied variants was characterized by very low content of humus, total nitrogen and nitrates before sowing of the crops. During the research period, the prevalence of dry years was noted. Nitrogen use coefficients of mineral fertilizers in the conditions of the dry-steppe zone of Buryatia on average for 39 years of research were 69% for wheat, 54% for oats and 90% for oats for grain haylage. The variation of the coefficients was significantly influenced by summer moistening conditions. They were 32% under extreme and severe drought, 57% under moderate and weak drought, and increased significantly (up to 124%) under favorable moisture conditions. The utilization of nitrogen of solid mineral fertilizers was maximum in the third crop (oats for grain haylage) and more responsive to the atmospheric moistening. The smallest consumption coefficients and the range of its changes were observed in oats for grain. The first crop of the rotation (fallow wheat) occupied an intermediate position in this assessment. The data on the influence of soil moisture and hydrothermal conditions of separate critical periods of vegetation on the variation of the coefficient of mineral fertilizer nitrogen utilization (N40) by wheat, oats, and oats for grain haylage were obtained. The correlation analysis showed that the most critical period for nitrogen consumption in wheat is June (r = 0.61), in oats – July (r = 0.51) and July–August for oats for grain haylage (r = 0.50–0.52). Multiple linear models of dependence of N fertilizer use coefficients on productive moisture content and hydrothermal conditions were made.

Lithofacies, stratigraphy and depositional history of Middle Muschelkalk evaporites (Zeglingen Formation) in northern Switzerland

In northern Switzerland, Middle Muschelkalk evaporites (Zeglingen Formation) were deposited under arid conditions in the southernmost part of the epicontinental Central European Basin during times of reduced inflow of sea water from the Tethyan realm. Because of their marginal position in the basin, direct and detailed correlation of Muschelkalk sediments of northern Switzerland with equivalent strata in interior parts of the basin is not straightforward. Based on detailed sedimentological logging of 640 m of drill cores from ten wells in northern Switzerland, 22 lithofacies and 10 lithofacies associations were distinguished for the Middle Muschelkalk evaporites. High-resolution regional correlations of gamma-ray logs record substantial thickness variation of the evaporites. Locally, dissolution was recognized by visual core examination that could be dated to Middle Triassic times and that was likely related to subsurface fluid flow along deeper seated faults. In combination with the regional thickness variation, the dissolution phenomena suggest a tectonically active depositional setting in the Middle Triassic. Middle Muschelkalk evaporites consist of nine types of mainly auto-cyclic shallowing- or brining-upward mini-cycles which form a correlatable succession of five distinct 4th order cycle-sets. Despite the tectonically active depositional environment, most lithofacies encountered appear to have nearly flat bounding surfaces. Thus, marine transgressions flooded wide areas nearly simultaneously. The corresponding deposits serve as reference levels to tie the peripheral facies of northern Switzerland into the supra-regional context.

Aridification alters the diversity of airborne bacteria in drylands of China

Dryland ecosystems, which vary sensitively to drought owing to climate change and human activities, frequently cause large-scale aeolian dispersal of terrestrial-mineral and biological particles. To date, very few studies have focused on the atmosphere-land exchange of bacteria in drylands. To understand the bacterial transport from the terrestrial environment to the atmosphere over drylands, soil and aerosol samples were collected at 19 sites in arid and semi-arid regions across drylands of China in the summer of 2017. The 16S rRNA gene sequencing revealed that the bacterial diversity in the atmosphere was significantly lower than that in terrestrial ecosystems for all the collected samples. Moreover, bacterial diversity in the atmosphere increases in arid regions compared to semi-arid regions, while those of the terrestrial environment were maintained regardless of the region. Additionally, the terrestrial bacterial sources contributed to the airborne bacteria more significantly in arid regions than those in semi-arid regions (accounting for 10.0 ± 1.1% and 3.5 ± 1.1%, respectively). The arid conditions tended to enhance the atmospheric emissions of Chloroflexi, while the members of Bacteroidetes were dominant in both the atmospheres of the semi-arid and arid regions. The differences in bacterial community structures between the terrestrial and atmospheric ecosystems are thought to depend on the ground surface characteristics such as vegetation and terrestrial substrates. Meteorological drought may alter terrestrial characteristics, which regulate airborne bacterial dispersal from dryland to its downwind regions, suggesting that more attention should be paid to the bacterial roles in the biology-health-climate process in the future.

Mineralogy and geochemistry of the Middle Jurassic coal from the Hexi Mine, Shenfu Mining Area, Ordos Basin: With an emphasis on genetic indications of siderite

Siderite is a common carbonate mineral in coal and usually contains geochemical indications (elemental associations and isotopic compositions) for sedimentary environments and regional geological history, but the origin and enrichment mechanism of geochemically-pure siderite in coal is not fully understood. A better understanding of siderite origin in coal can help to decipher the depositional environment of peat and related geological processes of rank advances and epigenesis. This paper analyzed the petrological, mineralogical, and geochemical characteristics, particularly the content, occurrence, and origins of siderite in the Middle Jurassic coal from the Hexi mine of the Shenfu mining area, Ordos Basin, using optical microscopy, field emission-scanning electron microscopy, X-ray fluorescence, X-ray diffraction, inductively coupled plasma mass spectrometry, and isotope ratio mass spectrometry. The results indicate that the No. 4 Coal is rich in inertinite and is defined as an ultra-low to low sulfur, high volatile bituminous coal. Siderite has contents varying from 5.8% to 54.4% (low temperature ash basis) and occurs in radial or concentric circle nodules in the coal and is mainly distributed within the clay matrix. Syngenetic siderite in the Hexi coals is relatively pure in chemical compositions, and was formed in a brackish water environment affected by salt lakes under arid conditions. The high content of inertinite, high Sr/Cu value, and positive Ce anomaly at the uppermost of the coal seam indicate that the escalating intensification of oxidation and evaporation. The Al2O3/TiO2 ratio and the diagrams of Al2O3/TiO2 vs. Zr/ TiO2 and Al2O3/TiO2 vs. Nb/Yb indicate that the sedimentary source rock in the study area is primarily intermediate-felsic. The δ13CPDB-δ18OSMOW diagram shows C and O for the siderite formation in this study were derived from marine carbonate rock alteration of the underlying Ordovician marine carbonate rock basement. The distribution patterns of rare earth elements and Y (Middle-type enrichment and Gd anomalies) in the coal further verify this hypothesis. Furthermore, siderite in the coal exhibits an enrichment in 13C suggest that bacterial fermentation of organic matter as another possible source of CO2. The iron of the siderite in the study coal was probably derived from the leaching of the magnetite-bearing granite.