Search Results (1,738)

Yunnan Province, a global biodiversity hotspot, hosts a diverse array of Acrididae grasshoppers essential for ecosystem dynamics and agriculture. To elucidate the phylogenetic relationships and evolutionary history of this group, we sequenced and analyzed complete mitochondrial genomes from 17 Acrididae species endemic to Yunnan, with genome lengths ranging from 15,403 to 15,943 base pairs. These data were integrated with mitochondrial sequences from 46 additional species to construct comprehensive phylogenetic trees. The maximum-likelihood tree identified four major clades with robust support (bootstrap values > 90%), revealing significant lineage diversification during the Early Eocene (51.94 million years ago, Mya) and subsequent radiations in the Miocene (~20 Mya) and Pliocene (~5 Mya). These divergence times correlate with major geological events and climatic shifts in the region, such as the uplift of the Tibetan Plateau and the intensification of the Asian monsoon. Notably, several species within the Coptacrinae and Oxyinae subfamilies, particularly Pseudodotraulia cornuata and Spathosternum prasiniferum, were found to be polyphyletic, indicating the necessity for taxonomic revisions. Further cluster analyses of codon usage bias and genetic distance support these taxonomic revisions within Acrididae. This robust phylogenetic framework underpins conservation strategies aimed at preserving Yunnan’s rich grasshopper biodiversity and informs updates to their phylogeny. Full article

Over the past decade, China has enacted forward-looking environmental policies that have significantly reduced air pollution. However, while there appears to be a synergy between economic development and improvements in air quality, regional imbalances in development and disparities in health risks underscore systemic challenges in environmental governance. This study employed a population-weighted exposure index to evaluate disparities in PM_2.5 exposure and its temporal and spatial trends, considering multidimensional socio-economic factors such as education, age, gender, occupation, and urban/rural backgrounds across 32 provinces and regions in China. The findings reveal that despite a notable decline in overall PM_2.5 concentrations between 2013 and 2020, improvements in air quality are uneven across regions, with less developed areas bearing a disproportionate burden of emission reductions. Urban centers exhibit lower exposure levels due to resource and industrial advantages, whereas towns experience higher risks of air pollution. Socio-economic disparities are evident, with increased exposure observed in high-pollution industries and among groups with lower educational attainment. Women are more likely to be exposed than men, and both the elderly and children face higher risks. To address these challenges, policies should focus on the economic development of underdeveloped regions, balance environmental protection with growth, prioritize heavily polluted areas and vulnerable populations, and promote the adoption of clean energy to mitigate pollution inequality. Full article

Using satellite-observed data and reanalysis data, we studied the spatiotemporal variation characteristics and dynamic mechanisms of thermal fronts in the Beibu Gulf (TFIBG). TFIBG occur in December, reach their strongest point in January in the following year, and then gradually weaken until they completely disappear in May. Their formation is related to the bathymetry of the Beibu Gulf. In winter, the seawater in shallow-water areas (deep-water areas) cools down more (less), and Ekman currents concurrently transport warm water from the central basin of the Beibu Gulf to the west coast, which results in the formation of a thermal front at the junction of cold and warm water. The interannual variation in TFIBG intensity is related to the northeast monsoon. The strengthened (weakened) Ekman current caused by the northeast monsoon transports more (less) warm water from the central basin of the Beibu Gulf to the west coast, forming a strong (weak) thermal front at the junction of cold and warm water on an interannual scale. The upward trend of TFIBG intensity may be related to the regional heterogeneity of climate warming. This research systematically studied TFIBG, which will help improve people’s understanding of the thermal front in the South China Sea (SCS). Full article

This study presents a high-resolution palaeoclimate reconstruction based on a radiocarbon-dated 240 cm deep trench profile from Renuka Lake, Northwestern Himalaya, India. The palynological analysis provides insight into the palaeovegetation and palaeoclimatic dynamics of a subtropical, dense, mixed deciduous forest, predominantly characterized by Sal (Shorea robusta). The fossil pollen reveals the presence of tropical Sal mixed deciduous taxa, including Shorea robusta, Emblica officinalis, Murraya koenigii, Toona ciliata, Syzygium cumini, and Terminalia spp., which indicate that the region experiences a warm and humid climate with the strong Indian Summer Monsoon (ISM) during ~7500–4460 cal yr BP. Subsequently, Sal-mixed deciduous forests were replaced by highland taxa, viz., Pinus roxburghii and Abies pindrow, suggesting dry and cold conditions during ~4460–3480 cal yr BP. Additionally, warm and humid (~3480–3240, ~3060–2680, ~2480–2270 cal yr BP) and cold and dry conditions (~3240–3060, ~2680–2480, ~2270–1965 cal yr BP) recorded alternatively in this region. Improved ISM prevailed ~1965–940 cal yr BP, followed by cold and dry conditions ~940–540 cal yr BP. From ~540 cal yr BP to present, the appearance of moist deciduous taxa alongside dry deciduous and highland taxa in similar proportions suggests moderate climate conditions in the region. Full article

Atmospheric water vapor is a critical factor influencing rainfall, snowfall, and avalanche occurrences, with its diurnal variations providing key insights into such phenomena. However, in high-altitude mountainous areas, the spatial and temporal resolution of water vapor products is insufficient to depict their diurnal variation characteristics. This study aimed to refine the understanding of diurnal Precipitable Water Vapor (PWV) variations using the ANUSPLIN to obtain a two-dimensional water vapor field with a resolution of 0.1° × 0.1° during the monsoon period from 2007 to 2015, which was verified based on ground-based GPS water vapor observations. The findings reveal that incorporating China Meteorological Forcing Data (CMFD) greatly enhances the diurnal variation patterns of PWV, resulting in the appearance of extreme values of PWV daily variation about three hours later than the MERRA reanalysis. In the southern Tibetan Plateau (TP), the diurnal variation of PWV is closer to GPS PWV in terms of amplitude and phase. Spatially, PWV variations are weaker in the central TP but stronger in other regions, particularly during the mid-monsoon period (July–August). Temporally, the central TP experiences maximum PWV from nighttime to early morning (18:00–4:00 UTC), while the surrounding southern and northern areas peak from afternoon to evening (8:00–12:00 UTC), approximately three hours earlier than precipitation peaks. Temporally, the central Tibetan Plateau experiences maximum PWV from nighttime to early morning (18:00–4:00 UTC), while the surrounding southern and northern areas peak from afternoon to evening (8:00–12:00 UTC), approximately three hours earlier than precipitation peaks. Full article

The response of trees to climate is crucial for the health assessment and protection of forests in alpine regions. Based on samples of Pinus tabuliformis and Abies fargesii, two typical evergreen coniferous species with distinct elevation differences in the vertical vegetation zones of the Qinling Mountains, we have developed two tree-ring width chronologies for the southern slope of the central Qinling Mountains in central China. The correlation analysis results showed that the radial growth of P. tabuliformis and A. fargesii responded to different climatic factors. Water stress caused by temperature in May of the current year was the main limiting factor for radial growth of P. tabuliformis, while precipitation in September of the previous year and the current year had a negative impact on A. fargesii, with lag effects of temperature and precipitation during the previous growing season. Spatial correlation and comparative analysis indicated that the P. tabuliformis chronology responded to extreme dry and wet events on a regional scale. Interannual and multidecadal periodic signals recorded by tree rings suggested that the hydrological and climatic changes on the southern slope of the central Qinling Mountains were teleconnected with the Pacific and Atlantic Oceans, including El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and North Atlantic Oscillation (NAO). Our results provide new evidence for a hydroclimatical response study inferred from tree rings on the southern slope of the central Qinling Mountains. Full article

This study investigated the impacts of reclaimed water (RW) irrigation on soil properties and landscape plant growth in a coastal monsoon city over a 13-month period. Soil properties in plots irrigated with RW and tap water (TW) were monitored monthly, including electrical conductivity, total nitrogen, total phosphorus, soil organic matter, and overall variations of soil enzyme activities. The results show that RW irrigation led to increased fluctuations in soil salinity indicators, with higher peaks during periods of low rainfall. Rainfall can efficiently mitigate the salinity increase associated with RW irrigation, highlighting the influence of monsoon climate variability on salinity dynamics. RW application increased soil total nitrogen and organic matter and decreased soil total phosphorus. This suggests that RW irrigation induces complex nutrient interactions within the soil–plant system. Furthermore, RW irrigation promoted the activities of soil enzymes related to carbon, nitrogen, and phosphorus cycling, indicating potential alterations in nutrient bioavailability. Plant growth responses varied among species, with Nephrolepis cordifolia and Cordyline fruticose exhibiting signs of salt stress, especially in the initial months of planting in RW plot. Other species demonstrated greater tolerance to RW irrigation, suggesting the importance of species selection for sustainable landscape management with RW. This study demonstrates the challenges and opportunities associated with RW utilization for urban greening. Full article

Hopea chinensis is a representative tree species in evergreen monsoon forests in the northern tropics, but it is currently in a critically endangered state due to destruction by human activities and habitat loss. In this study, we measured and analyzed the number of regenerating seedlings and habitat factors in wild populations of H. chinensis by combining field surveys with laboratory analysis. The aim of this study was to clarify the spatial distribution of H. chinensis seedlings and related factors to provide a scientific basis for conserving its germplasm resources and population restoration. In six populations, most size-class seedlings had aggregated distributions at three scales, and the intensity of aggregation decreased as the sample plot scale increased for most size-class seedlings. In the northern foothills of the Shiwandashan Mountains, size class I seedlings tended to be distributed in habitats with a higher rock bareness rate, whereas size class II and III seedlings tended to be distributed in habitats with a higher canopy density, thicker humus layers, and higher soil moisture content. In the southern foothills of the Shiwandashan Mountains, size class I and II seedlings tended to be distributed in habitats with higher available nitrogen contents, and size class III seedlings tended to be distributed in habitats with higher available nitrogen and soil moisture contents. Therefore, in the southern foothills of the Shiwandashan Mountains, the survival rate of H. chinensis seedlings can be improved by artificially adding soil to increase the thickness of the soil layer in stone crevices and grooves, regularly watering the seedlings during the dry season, and appropriately reducing the coverage of the shrub layer. In the northern foothills, the survival rate of H. chinensis seedlings can be enhanced by regularly applying nitrogen fertilizer and watering to increase the available nitrogen and soil moisture contents. Full article

Different scenarios have been established and simulated based on the Delft3D model to compare and assess the impact of human activities (increased pollutants as oxygen demand, BOD, COD, nutrients, and land reclamation), climate change (rising temperatures, sea level rise), and a combined scenario of human activities and climate change on water quality in the Cat Ba–Ha Long coastal area. The findings quantify the impacts of anthropogenic activities and climate change on the water quality in the study area in 2030 and 2050. During the northeast monsoon and the two transitional seasons, the impact of humans and climate change adversely affects water quality. The impact of climate change is less significant than that of human activities and their combination, which result in a reduction in DO levels of 0.02–0.13 mg/L, 0.07–0.44 mg/L, and 0.09–0.48 mg/L, respectively. Meanwhile, during the southwest monsoon, climate change significantly reduces water quality (0.25–0.31 mg/L), more so than human activities (0.14–0.16 mg/L) and their combined effects (0.13–0.17 mg/L). This may elucidate the fact that the increase in nutrient supply from the river during the southwest monsoon in this region can result in an increase in nutrient levels and biological activity, which, in turn, causes an increase in DO. Additionally, the augmented quantity of DO may partially offset the decrease in DO resulting from climate change. Under the influence of human activities and climate change, the nutrient levels in the area increase, with average values of 0.002–0.033 g/m³ (NO₃⁻), 0.0003–0.034 g/m³ (NH₄⁺), and 0.0005–0.014 g/m³ (PO₄³⁻). Full article

The impacts of climate change on snowfall have received great interest in cold regions for water resource and flood risk management. This study investigated the effects of rises in air and sea surface temperatures and sea ice on snowfall in Hokkaido, northern Japan, over the period from 1961 to 2020 (60 years). Climate data observed at the 22 weather stations operated by the Japan Meteorological Agency (JMA) were analyzed. Statistics describing the effects of climate change on snowfall were computed. The trend in these quantities was obtained using Sen’s slope estimator, and their statistical significance was evaluated by the Mann–Kendall test. The warming trends obtained at these stations were all positive and statistically significant. Annual snowfall increased at seven stations but decreased at two stations. The snowfall period decreased mainly on the southern coast. This is attributed to the fact that these sites are on the leeward side of the Eurasian monsoon, and that air temperatures on the coast and the surface temperature of the sea off Kushiro have risen sufficiently. The results suggest that the flood risk may increase in response to the acceleration of the increase in the level of a river due to early melting snow in spring (March and April). Although the weather stations on the east coast are also on the leeward side, the snowfall period has not shortened. The warming trends in April are very weak on the east coast. The correlation between the air temperature in March and April and the period of sea ice accumulation suggests that melting sea ice in spring plays an important role in preventing the winter period from shortening. Decrease in sea ice due to a rise in both air and sea surface temperatures may increase flood risk in early spring, and thus, some measures may need to be taken in the future. Full article

This study investigated the source, trajectory, and precipitation of the Southwest (SW) vortex, which was linked with the Plateau (P) vortex. Based on the statistical study of a number of cases, this study showed the following results. The SW vortex tended to originate at the northeastern and western peripheries of the Sichuan Basin, normally coinciding with the presence of the P vortices in the eastern region of the Tibetan Plateau. Most of the aforementioned vortices exhibited a longer life span, and resulted in severe storms averaging approximately 50 mm of rainfall per day, especially in the cases of more than 100 mm of rainfall per day in eastern and southern China. Furthermore, new findings were obtained: (1) The SW vortex and the P vortex were attributed from an ‘Ω’ circulation pattern from blocking high in middle to high latitudes region. The SW vortex was notably influenced by the convergence of two air currents. In the lower troposphere, the southwesterly jet of the South Asian monsoon flowed over and around the Yungui Plateau, and cold–dry air from the north flowed into the Basin. (2) Both the SW vortex and the P vortex displayed a shallow synoptic system characterized below 500 hPa, and wet–cold cores formed around the sources at low altitudes. (3) The analysis on atmospheric instability and dynamics suggested that the vortices’ eddies generated significant convective instability at lower levels. The circulation pattern and instability conditions facilitated the heavy precipitation associated with the SW vortex, and the ample water vapor and subsequent latent heat intensified the precipitation. Full article

Influenced by factors such as the freeze–thaw cycle and water–salt migration, road construction in Uzbekistan’s highway project areas is prone to dissolution and subsidence, salt swelling, corrosion, and other engineering diseases. To investigate how various factors impact saline soils in Uzbekistan’s monsoon freezing zone, we conducted analyses of stress–strain curves, failure strength, and shear strength parameters of these soils through freeze–thaw (F-T) cycle tests and unconsolidated and undrained (UU) triaxial shear tests. The findings indicate that with the increase of salt content, the average reduction in the failure strength of saline soil was 15.8%, 6.3%, and 5.7%; with the increase of water content, the average reduction in cohesion was 10.8%, 44.1%, and 32.6%; and the internal friction angle increased with the increase of the number of F-T cycles and decreased with the increase of freezing temperature. Ultimately, we defined the rates of failure strength deterioration and cohesion damage in saline soil due to various factors, analyzing the destructive impacts of these factors. The results demonstrate a strong correlation between the curves of failure strength deterioration and cohesion damage ratios, indicating that the significant degradation of saline soil due to salt is primarily influenced by F-T cycles, with the extent of damage closely linked to water content. Full article

The transplanting of over-aged seedlings is an important adaptive strategy for rice cultivation during the monsoon season in the coastal areas of Bangladesh. This study aimed to identify promising hybrid rice varieties that can be transplanted as over-aged seedlings in the south-central tidal coastal ecosystem of Bangladesh. Three elite hybrid varieties, namely, AZ7006, Dhani Gold, and INH-16019, along with a popular local cultivar, Moulata (as the control), were used in this field study, and seedlings at two different ages (e.g., 50- and 60-day-old) were transplanted. The results showed that Dhani Gold had the highest grain yield (5.47 t/ha) with the maximum number of tillers (17) and effective tillers (15) per hill for the 50-day-old seedlings as compared with the 60-day-old seedlings. In addition, the hybrid variety INH-16019 also yielded 5.20 t/ha grain with the highest number of spikelets/panicle (191), filled grains/panicle (174), and unfilled grains/panicle (17) for 50-day-old seedlings. However, the local cultivar, Moulata, had the highest plant height (149 cm), required the maximum time for 50% flowering (75 days after transplanting, DAT) and harvesting (104 DAT), and also produced the lowest number of spikelets/panicle (114) and filled grains/panicle (108), leading to the lowest grain yield (3.57 t/ha) considering both ages of the seedlings. Our data further revealed the significant influence of seedling age (50- and 60-day-old seedlings) on the straw yield. Interestingly, this study revealed that the hybrid variety Dhani Gold showed a remarkable decrease in straw yield (by 36%) but obtained the highest (56.3%) harvest index when transplanted as very over-aged (e.g., 60-day-old) seedlings. Moreover, we recorded a higher grain nitrogen content in the hybrid varieties than in the local cultivar, Moulata. Among the hybrids, AZ7006 showed the highest nitrogen content (1.72%), which was statistically similar to INH-16019 (1.67%) and Dhani Gold (1.57%) for 50-day-old seedlings. Importantly, the grain yield of Dhani Gold was 50% higher than Moulata for 50-day-old seedlings, and the benefit–cost ratio of Dhani Gold was also the highest (1.34) for the same seedling age. Hence, the over-aged Dhani Gold hybrid rice seedlings would be a good choice for increasing Aman rice productivity during the monsoon season in the south-central coastal ecosystem of Bangladesh. Full article

Lakes are vital freshwater ecosystems that sustain biodiversity, support livelihoods, and drive socio-economic growth globally. However, they face escalating threats from anthropogenic activities, including urbanization, agricultural runoff, and pollution, which are exacerbated by climate change. Phewa Lake in Nepal was selected for this study due to its increasing rates of nutrient enrichment, sedimentation, and pollution. This study evaluated seasonal and spatial water quality variations within the lake by analyzing water samples from 30 sites during the pre-monsoon and post-monsoon seasons. Twenty physicochemical parameters, including the potential of hydrogen (pH), dissolved oxygen (DO), electrical conductivity (EC), and major ions, e.g., calcium (Ca²⁺), magnesium (Mg²⁺), sodium (Na⁺), potassium (K⁺), bicarbonate (HCO₃⁻), chloride (Cl⁻), sulfate (SO₄²⁻), nitrate (NO₃⁻), phosphate (PO₄³⁻), and ammonium (NH₄⁺), were measured. The average pH ranged from 8.06 (pre-monsoon) to 8.24 (post-monsoon), reflecting dilution from monsoon rains and increased carbonate runoff. Furthermore, the DO levels in Phewa Lake averaged 7.46 mg/L (pre-monsoon) and 8.62 mg/L (post-monsoon), with higher values observed post-monsoon due to rainfall-driven oxygenation. Nutrient concentrations were shown to be elevated, with the nitrate concentration reaching 2.31 mg/L during the pre-monsoon period, and the phosphate concentration peaking at 0.15 mg/L in the post-monsoon period, particularly near agricultural runoff zones. The dominant cations in the lake’s hydrochemistry were Ca²⁺ and Mg²⁺, while HCO₃⁻ was the primary anion, reflecting the influence of carbonate weathering. Cluster analysis identified the lake outlet as a high-pollution zone, with the total dissolved solids (TDS) reaching 108–135 mg/L. Additionally, Principal component analysis revealed agricultural runoff and sewage effluents as the main pollution sources. Seasonal dynamics highlighted monsoon-induced dilution and pre-monsoon pollution peaks. These findings underscore the need for targeted pollution control and eutrophication management. By aligning with the sustainable development goals (SDGs) relevant to clean water and climate action, this research provides a replicable framework for sustainable lake management that is applicable to freshwater ecosystems worldwide. Full article

This study aimed to explore the contamination of aflatoxins by investigating the spatial distribution of aflatoxin B1 (AFB1) in cow feedstuff and aflatoxin M1 (AFM1) in raw milk, and the potential health risks of AFM1 in milk and dairy products. Feedstuff and raw milk were collected from 160 pastures in three climate zones of China from October to November 2020. The results indicated the level of AFB1 and AFM1 ranged from 51.1 to 74.1 ng/kg and 3.0 to 7.0 ng/kg, respectively. Spatial analysis indicated the contamination was mostly concentrated in the temperate monsoon climate zone. On average, the estimated dietary exposure to AFM1 from milk and dairy products for Chinese consumers ranged from 0.0138 to 0.0281 ng/kg bw/day, with the MOE values below 10,000, and liver cancer risk of 0.00004–0.00009 cases/100,000 persons/year. For different groups, the average exposure to AFM1 was highest in the temperate monsoon climate zone and for toddlers. Full article