Taihang Mountains Research Articles

Evolution of habitat quality and association with land-use changes in mountainous areas: A case study of the Taihang Mountains in Hebei Province, China

Landscape patterns have a large impact on biodiversity in ecosystems. As a proxy for biodiversity research, assessing changes in habitat quality (HQ) induced by land-use/land-cover (LULC) changes will provide a scientific foundation for ecological protection and land resource management, especially in the ecologically fragile regions such as mountainous areas. Based on land-use data covering the period from 1990 to 2020 from the Taihang Mountains of Hebei Province, this paper selected 10 landscape metrics at the class and landscape levels to examine the dynamics of LULC. Then, this study evaluated HQ by employing the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model and quantitatively analyzed the impact of land use changes on HQ using a geographically weighted regression (GWR) model. The results showed that arable land, grassland and forestland were the main land categories in the study area, and the major changes were the conversion of arable land and grassland to construction land during 1990–2020. During the research period, landscape patches tended to fragment, shape complexity and varied and were evenly distributed. Overall, the region had a high HQ, but the average HQ has exhibited a declining trend in the past 30 years. In addition, changes in HQ were significantly related to land-use changes, and the areas dominated by construction land or arable land, which were closely related to anthropogenic activities, had a relatively low HQ. To balance the tradeoff between economic development and ecological integrity, a social-ecological systems perspective is needed in the design of political-economic policies. This research could improve our understanding of the effects of land-use pattern dynamics on HQ, which has important significance in preserving biodiversity, safeguarding ecological security, and achieving the sustainability of the ecological environment.

How to reconcile land use conflicts in mega urban agglomeration? A scenario-based study in the Beijing-Tianjin-Hebei region, China

With the development of global urbanization, land use conflicts have become one of the major issues hindering sustainable land use and human-environment coordination in urbanized areas. In this context, reconciliation of land use conflicts requires urgent attention. By taking the Beijing-Tianjin-Hebei (BTH) urban agglomeration as a case study area, the spatial comprehensive conflict index (SCCI) was constructed to identify and evaluate land use conflicts. Besides, the impacts of rapid urbanization and terrain restriction on land use conflicts were also explored using the coupling coordination degree (CCD) model and terrain index, respectively. Then, the Dyna-CLUE model was adopted to simulate land use conflicts under three adaptive scenarios in 2030. Results show that: (1) During 2000–2015, land use conflicts in the BTH region demonstrated an overall mitigating trend, and their spatial patterns remained relatively stable, characterized by significant cluster and belt agglomeration. (2) Land use conflicts were significantly intensified in areas experiencing rapid urban-rural transformation and terrain transition, and two typical conflict zones were identified, i.e. the urban-rural interface of the Beijing-Tianjin region and the terrain transition area located in the Taihang Mountains, Yan Mountains and Bashang Plateau. (3) In 2030, land use conflicts in the BTH region manifest overall mitigation under the ecological security (ES) scenario, while demonstrating an intensifying trend under the business as usual (BAU) scenario and cropland protection (CP) scenario. Based on simulation results, land use spatial optimization modes at county level for the BTH region were formulated. In face of increasingly prominent land use conflicts globally, this study will provide a scientific reference for policymaking in pursuit of sustainable land use management for the BTH region and urban agglomerations in other parts of the world.

Controlling factors of soil saturated hydraulic conductivity in Taihang Mountain Region, northern China

In this study, 152 undisturbed soil samples from the 0–10 cm and 10–20 cm soil depths along two transects across the Taihang Mountain Region in northern China were investigated. The effect of soil properties (bulk density (BD), capillary porosity (CP), non-capillary porosity (NCP), soil organic carbon (SOC), and sand, silt, and clay contents) and environmental properties (land use type, topographical location, and elevation) on the Ks was determined. Moreover, the direct and indirect effects of these factors on the Ks were determined using the structural equation modeling (SEM). The results show that the Ks of the 0–10 cm soil depth (4.48 m/d) is significantly (p < 0.05) higher than that of the 10–20 cm soil depth (3.31 m/d), suggesting more rapid infiltration in the surface soil depth. The coefficients of variance (CVs) are 0.75 and 1.03 for the surface and sub-surface depths, respectively, indicating moderate and strong variations in the Ks in the two depths. The SEM revealed that most of the effects of the environmental properties on the Ks are indirect, accounting for 80.5% and 90.9% of the total effect in the surface and sub-surface soil depths, respectively. This demonstrates that the composite soil property was the direct, but the composite environmental property was the indirect factors influencing the Ks. These results deepen our existing understanding of the factors controlling the Ks in mountainous regions.

Modern pollen-vegetation relationships in the Taihang Mountains: Towards the quantitative reconstruction of land-cover changes in the North China Plain

Pollen-based land cover reconstructions are important for understanding the history of regional environmental responses to natural and anthropogenic factors, and for managing the ecological environment. The vegetation in the mountain landscape of North China has been significantly influenced by human activities, and evaluating the pollen-vegetation relationship for the region is important for reconstructing anthropogenic land-cover changes in the North China Plain. In this study, 35 sampling sites were randomly selected in representative vegetation zones of the Taihang Mountains in North China. Based on a detailed vegetation survey (field work combined with the analysis of remote sensing images), we evaluated the pollen-vegetation relationships in the area. In addition, the relevant pollen source area (RSAP) of the sampling sites and the relative pollen productivity (RPP) of the major plant taxa were estimated using ERV (Extended R-Value) models. The results show that the pollen spectra in the Taihang Mountains reliably reflect the vegetation landscape of different altitudinal zones. The estimated RSAP in the Taihang Mountains is ~ 600 m. Using Poaceae as a reference taxon (RPP = 1), the RPPs of the dominant plant taxa in the Taihang Mountains can be ordered as follows: Pinus > Hippophae > Caryophyllaceae > Betula > Quercus > Rhododendron > Artemisia > Asteraceae > Cyperaceae. Our results suggest the importance and complexity of RPP estimates in the Taihang Mountains, and provide valuable implications for improving the accuracy of reconstructions of land-cover changes in the North China Plain.

Analysis of strength property and pore characteristics of Taihang limestone using X-ray computed tomography at high temperatures

Rising temperature will cause the changes of pore characteristics and strength property in rock. This research takes the limestone produced in Taihang Mountains as the research object, and performs high-temperature treatment within 25–1000 °C. The high-resolution X-ray computed tomography (CT) scanning test method is used to visually reconstruct the three-dimensional image of the sample, and obtain the spatial distribution status of the mesoscopic parameters of the bones, pores/cracks, etc. The results show that when the temperature exceeded 700 °C, the samples appeared milky white in appearance and as the temperature increased, the color gradually turned white, macroscopic cracks began to appear on the surface, while the meso-pores connected rapidly, reflecting a typical progressive destruction process from inside to outside. The change law of volume porosity with temperature has a consistent trend with that of the apparent morphology of the sample. Similarly, the mechanical test results suggest that 700 °C is also the turning temperature for strength deterioration and brittle-plastic transformation of sample. Based on the results of high-temperature test, CT test and mechanical test, there are enough evidences to show that, for the limestone sample, 700 °C is probably to be the mutation temperature of physical–mechanical behavior.

Spatial Distribution Pattern and Influencing Factors of Sports Tourism Resources in China

Sports tourism is an emerging tourism product. In the sports and tourism industry, resource mining is the foundation that provides positive significance for theoretical support. This study takes China’s sports tourism boutique projects as the study object, exploring its spatial distribution pattern through the average nearest neighbor index, kernel density, and spatial autocorrelation. On the strength of the wuli–shili–renli system approach, the entropy value method and geographic detector probe model are used to identify the driving factors affecting the spatial distribution pattern. Findings reveal the following: (1) From 2013 to 2014, the sports tourism resources in China present a distribution pattern with the Yangtze River Delta urban agglomeration as the high-density core area and the Guizhou–Guangxi border area and the western Hubei ecological circle as the sub-density core areas. (2) From 2014 to 2018, China’s sports tourism boutique projects increased by 381, and the regional differences among various provinces tended to converge. The high-density core area remained unchanged. The sub-density cores are now the Yunqian border area of the Karst Plateau, the Qinglong border area of the Qilian Mountains, and the Jinji border area of the Taihang Mountains, shaping the distribution trends of “depending on the city, near the scenery” and “large concentration, small dispersion”. (3) The proportion of provincial sports tourism development classified as being in the coordinated stage is 61.29%. (4) The explanatory power of the factors affecting the spatial layout in descending order is natural resource endowment, sports resource endowment, transportation capacity, industrial support and guidance, market cultivation and development, people’s living standards, software and hardware services, and economic benefit effects. The explanatory power of the interaction of two different factors is higher than that of the single factor.

Recent expansion of talus slopes in the northern Taihang Mountain Range, China: an example from the Xiaowutai Region

Recent expansion of talus slopes in the northern Taihang Mountain Range, China: an example from the Xiaowutai Region

Sensitivity of PM2.5 and O3 pollution episodes to meteorological factors over the North China Plain

The Comprehensive Air-quality Model with extensions (CAMx) was used to explore the sensitivity of PM2.5 and O3 concentrations to four selected meteorological factors: wind speed, temperature, water vapor mixing ratio (Q), and planetary boundary layer height (PBLH) during two pollution episodes over the North China Plain (NCP). We also investigated the impact pathways of different meteorological factors on the formation of PM2.5 and O3. It is found that PM2.5 was more sensitive to the selected meteorological factors in the southeastern NCP, where high anthropogenic emissions and severe air pollution occur. Large variations were observed along the Taihang Mountains, where the height of the terrain changes dramatically. The sensitivity of O3 to wind speed, PBLH, temperature, and Q was mainly determined by the inhibition effects of PM2.5 in winter, while in summer, the complex chemical reactions were dominant. Significant diurnal variations of process analysis (PA) results were observed under various meteorological conditions. Higher temperature generally enhance heterogeneous chemistry and transport of NO3− through the top boundary layer during night-time in winter, however, in summer, the heterogeneous chemistry of NO3− and NH4+ during daytime were the major pathways to the increased PM2.5 due to increased temperature. Moreover, temperature alter PM2.5 concentrations through affecting vertical diffusivity and relative humidity, and alter O3 concentrations by affecting the gas phase chemistry and mass fluxes through the top boundary layer. Q mainly affects the rate of chemical reactions of PM2.5 and O3. The different impact pathways suggest that it is essential to consider variations in meteorological factors, in addition to the direct impacts of wind speed and PBLH, more attention should be paid to the complex impacts of temperature and Q, when developing emission control strategies.

Adjoint traveltime tomography unravels a scenario of horizontal mantle flow beneath the North China craton

The North China craton (NCC) was dominated by tectonic extension from late Cretaceous to Cenozoic, yet seismic studies on the relationship between crust extension and lithospheric mantle deformation are scarce. Here we present a three dimensional radially anisotropic model of NCC derived from adjoint traveltime tomography to address this issue. We find a prominent low S-wave velocity anomaly at lithospheric mantle depths beneath the Taihang Mountains, which extends eastward with a gradually decreasing amplitude. The horizontally elongated low-velocity anomaly is also featured by a distinctive positive radial anisotropy (VSH > VSV). Combining geodetic and other seismic measurements, we speculate the presence of a horizontal mantle flow beneath central and eastern NCC, which led to the extension of the overlying crust. We suggest that the rollback of Western Pacific slab likely played a pivotal role in generating the horizontal mantle flow at lithospheric depth beneath the central and eastern NCC.

Boundary layer structure characteristics under objective classification of persistent pollution weather types in the Beijing area

Abstract. Different types of pollution boundary layer structures form via the coupling of different synoptic systems and local mesoscale circulation in the boundary layer; this coupling contributes toward the formation and continuation of haze pollution. In this study, we objectively classify the 32 heavy haze pollution events using integrated meteorological and environmental data and ERA-Interim analysis data based on the rotated empirical orthogonal function method. The thermodynamic and dynamic structures of the boundary layer for different pollution weather types are synthesized, and the corresponding three-dimensional boundary layer conceptual models for haze pollution are constructed. The results show that four weather types mainly influence haze pollution events in the Beijing area: (a) type 1 – southerly transport, (b) type 2 – easterly convergence, (c) type 3 – sinking compression, and (d) type 4 – local accumulation. The explained variances in the four pollution weather types are 43.69 % (type 1), 33.68 % (type 2), 16.51 % (type 3), and 3.92 % (type 4). In persistent haze pollution events, type 1 and type 2 surpass 80 % on the first and second days, while the other types are present alternately in later stages. The atmospheric structures of type 1, type 2, and type 3 have typical baroclinic characteristics at mid–high latitudes, indicating that the accumulation and transport of pollutants in the boundary layer are affected by coupled structures in synoptic-scale systems and local circulation. The atmospheric structure of type 4 has typical barotropic characteristics, indicating that the accumulation and transport of pollutants is primarily affected by local circulation. In type 1, southerly winds with a specific thickness and intensity prevail in the boundary layer, which is favorable for the accumulation of pollutants in plain areas along the Yan and Taihang Mountains, whereas haze pollution levels in other areas are relatively low. Due to the interaction between weak easterly winds and the western mountains, pollutants accumulate mainly in the plain areas along the Taihang Mountains in type 2. The atmospheric vertical structure is not conducive to upward pollutant diffusion. In type 3, the heights of the inversion and boundary layers are the lowest due to a weak sinking motion while relative humidity is the highest among the four types. The atmosphere has a small capacity for pollutant dispersion and is favorable to particulate matter hygroscopic growth; as a result, type 3 has the highest PM2.5 concentration. In type 4, the boundary layer is the highest among the four types, the relative humidity is the lowest, and the PM2.5 concentration is relatively lower under the influence of local mountain–plain winds. Different weather types will shape significantly different structures of the pollution boundary layer. The findings of this study allow us to understand the inherent difference among heavy pollution boundary layers; in addition, they reveal the formation mechanism of haze pollution from an integrated synoptic-scale and boundary layer structure perspective. We also provide scientific support for the scientific reduction of emissions and air quality prediction in the Beijing–Tianjin–Hebei region of China.

Chronological and geochemical variations of the late Mesozoic granitoids in the Taihang Mountains and middle-southern Tan-Lu Fault: Implications for lithosphere destruction of the North China Craton

In the Late Mesozoic, the North China Craton (NCC) underwent significant lithospheric thinning and destruction, especially in the eastern part, but the mechanism and timing related to this process are still contentious. The Taihang Mountains (TH) are located in the western part of the eastern NCC and the Tan-Lu Fault (TLF) is in the eastern part, which are two essential magmatic areas that reveal deep processes of magma origin. We investigated the spatial-temporal distribution of igneous rocks from these two areas to constrain the tectonic setting and magmatic sources. SHRIMP zircon U-Pb ages of the granitoids within the Fangshan pluton in northern TH area range from 136 to 128 Ma. Their <i>ε</i>_Hf(t) values and δ¹⁸O values show ranges of −27.7 to −18.5 and 6.68 to 7.26 permil, respectively. Hence, we conclude that the rocks were formed by mixing between underplating magma and the melts from the lower crust. The O-Hf isotopic compositions of six granitoid samples from the Yunmengshan complex in northern TH are also reported. In combination with previous studies, we propose that the geochemical characteristics of the magmatic rocks from the TH area had insignificant changes during late Mesozoic time, but the rocks from the TLF area varied greatly. The difference between those two areas may reflect the diverse impact of the Paleo-Pacific subduction process. The high Mg# adakitic rocks (HMA) from TLF area have higher Mg# values than the HMA rocks from TH area. Our conclusion is that the HMA rocks in the TLF area were mainly formed by delaminated lower crust interacting with mantle materials and that the Paleo-Pacific subduction had limited impact on TH magmas. Based on chronology and geochemical characteristics, we recognize three stages: 1) ∼166 to 140 Ma, multi-directional compression resulted in crustal shortening and thickening in the NCC, accompanied by regional partial melting of the crust and underplating of mafic magmas, 2) 140 to 125 Ma, the TLF underwent left-lateral strike-slip movement. Subsequent delamination of the lower crust around the fault and the NCC evolved into an extensional tectonic environment, 3) after 125 Ma, a large-scale extension of the NCC occurred likely due to stress relaxation after delamination. The TLF acted as a favorable channel for transporting mantle material and fluids, which implies that the large-scale fault zone was a key factor of the NCC lithosphere destruction.

Spatial and temporal variations of hydrogen and oxygen isotopes and sources of water vapour indicated from satellite precipitation products along the transection of 38°north latitude in North China

The variations of hydrogen and oxygen isotopes in rainfall are critical for understanding the sources of rainfall and the influence of local evaporation. Satellite precipitation products with high time resolution (for instance 1 h) could be helpful for testifying the accuracy of water sources, as it can clearly illustrate the route of cloud movement. In this study, we analyzed the composition of hydrogen and oxygen isotopes in different rainfall events in three stations from 2015 to 2018 along the transection of 38° N latitude from Taihang Mountains to the coastal region in North China, Taihang Mountain Station (mountainous area), Luancheng Station (pre-mountain plain) and Nanpi Station (coastal low plain). By selecting typical rainfall events, water vapor sources and its influence rainfall on hydrogen and oxygen isotopes were analyzed with hourly available CMORPH satellite precipitation products. Results showed that the hydrogen and oxygen isotopes of precipitation were cha-racterized by enrichment in the rainy season and depletion in the dry season. The hydrogen and oxygen isotopes in the rainy season showed a tendency of depletion with the increases of precipitation. The slope and intercept of the fitted relationship of hydrogen and oxygen isotopes in the piedmont region of the mountains were the lowest, indicating that precipitation in the piedmont plain was significantly affected by secondary evaporation fractionation. The effect of evaporation resulted in the largest variations of isotope ratio in the dry year. In the mountainous station, due to the heavy rainfall, large isotopic variation was found in rich precipitation year. Based on the route analysis of sate-llite precipitation products, dominant water vapor in the region was inland and northwest-oriented water vapor, while water vapor in the rainy season was from southwest and from the Pacific Ocean. There was a significant difference in the hydrogen and oxygen isotopes of precipitation in the mountainous and plain stations in 2016, owing to water vapor sources and effects of rainfall for the mountainous and evaporation for plain. The results from HYSPLIT model showed that during the rainstorm on 19th July in 2016, water vapor at the mountainous station was mainly from the southwest, while that in the coastal plain was a mixture of southwest and southeast sources. Overall, our results showed that spatial and temporal variations of hydrogen and oxygen isotopes were controlled by both water sources and evaporation processes along the transection of 38° north latitude in North China.

Study on Spatial Pattern of Regional Tourism under Influence of High-Speed Tourism Corridor: Case Study of Taihang Mountain Expressway

In order to study the influence of Taihang Mountain Expressway on the tourism industry pattern of Taihang Mountain area in Hebei Province, the vector data of Taihang Mountain Expressway, the data of 43 exit nodes along the Expressway and the data of 76 scenic spots above 3A level are collected and sorted out. The unique association of the scenic spot-expressway exit node is constructed, the sum of the fuzzy contact intensities of the scenic spot-expressway exit nodes and the sum of the fuzzy contact intensities of the associated scenic spot nodes of each expressway exit are calculated, the fuzzy agglomeration of each exit node is calculated, and the spatial tourist grouping scheme based on COP objective function is analyzed and adjusted by the using the improved F-AMST model (designed with twice-splitting and twice-clustering). The result shows that (1) under the influence of Taihang Mountain Expressway, the result of spatial tourist grouping in this area includes 4 primary groups and 8 secondary groups; (2) by comparing with the results of previous studies of the division of mountainous tourism agglomeration areas in Hebei Province, the result of spatial tourist grouping is basically consistent with those of mountainous tourism agglomeration areas, but the fuzzy clustering intensity of spatial tourist grouping is significantly better than that of agglomeration division, that is, the completion and opening of Taihang Mountain Expressway enhances the agglomeration among scenic spots; (3) under the influence of Taihang Mountain Expressway filtration effect, there are 18 'vacuum filtration' nodes without scenic area connection and 3 'secondary filtration' nodes with less fuzzy association intensity; (4) Taihang Mountain Expressway provides opportunities and possibilities for the formation of new tourist destination geospatial patterns, the grouping of cross-administrative region boundary, and the combination of 'fast-slow' combined transport network system.

Tracking the spatio-temporal change of planting area of winter wheat-summer maize cropping system in the North China Plain during 2001–2018

Discriminating winter wheat-summer maize distribution is fundamental for agricultural water resources management in the North China Plain (NCP) which confronts severe conflicts between food production and agricultural water scarcity. However, how the planting area changed since 2000 is still unclear. Therefore, the winter wheat-summer maize from 2001 to 2018 was identified by using the maximum likelihood algorithm of supervised classification based on the Moderate Resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index (NDVI) product. Three schemes with different temporal resolutions of MODIS data and sample categories were compared to obtain the most reasonable identification results. The results reveal that using 16-day 0.0025° MODIS NDVI data and six sample categories including winter wheat-summer maize, winter wheat-rice, spring maize, cotton, other one cropping systems and other double cropping systems is an effective way for tracking the variation of winter wheat-summer maize distribution. The winter wheat-summer maize planting area showed an insignificant increasing trend at a rate of 34.2 km2/year (p = 0.955, CV = 7.49%) during 2001–2018, while it decreased at the rate of −5065.2 km2/year (p = 0.074) after 2012. Spatially, the planting area shrunk in northern NCP, the piedmont plain of the Taihang Mountains, the west of dry sub-humid zone and the southwest part of the NCP, accounting for 58.6% of the counties during 2001–2018; while 17.3% of the counties significantly expanded winter wheat-summer maize in the irrigation district along the Yellow River in Shandong province, the southeast of Hebei Plain and the central humid zone. Our results provide fundamental information for quantifying the change of crop water consumption and optimizing crop water resource allocation.

Demographic history and local adaptation of Myripnois dioica (Asteraceae) provide insight on plant evolution in northern China flora.

The flora of northern China forms the main part of the Sino‐Japanese floristic region and is located in a south–north vegetative transect in East Asia. Phylogeographic studies have demonstrated that an arid belt in this region has promoted divergence of plants in East Asia. However, little is known about how plants that are restricted to the arid belt of flora in northern China respond to climatic oscillation and environmental change. Here, we used genomic‐level data of Myripnois dioica across its distribution as a representative of northern China flora to reconstruct plant demographic history, examine local adaptation related to environmental disequilibrium, and investigate the factors related to effective population size change. Our results indicate M. dioica originated from the northern area and expanded to the southern area, with the Taihang Mountains serving as a physical barrier promoting population divergence. Genome‐wide evidence found strong correlation between genomic variation and environmental factors, specifically signatures associated with local adaptation to drought stress in heterogeneous environments. Multiple linear regression analyses revealed joint effects of population age, mean temperature of coldest quarter, and precipitation of wettest month on effective population size (Ne). Our current study uses M. dioica as a case for providing new insights into the evolutionary history and local adaptation of northern China flora and provides qualitative strategies for plant conservation.

Measuring the Impact of the Multiple Cropping Index of Cultivated Land during Continuous and Rapid Rise of Urbanization in China: A Study from 2000 to 2015

With the continuous and rapid rise of urbanization in China, land use transition research has been carried out extensively. Multiple cropping is the content of land use recessive morphology research, and it is also a common agricultural system in China. Accordingly, further research on multiple cropping index (MCI) can enrich the land use transition research and help to evaluate China’s food security. In order to examine the spatiotemporal changes and factors influencing the MCI of cultivated land in China, we collected MODIS remote sensing image data and land use classification data and conducted a remote sensing inversion on China’s MCI from 2000, 2005, 2010, and 2015. The spatial distributions and evolution processes of the MCI were explored through spatial mapping, statistical analysis, and processing with the Geographic Information System; moreover, the influencing factors of MCI were explored quantitatively with principal component regression. The results were as follows: (1) at the provincial scale, the average MCI across Guangdong, Guangxi, Hainan, Henan, Anhui, and Jiangsu was high; meanwhile, the average MCI across Heilongjiang, Inner Mongolia, Ningxia, and Qinghai was low. Between 2000 and 2015, the number of provinces with low MCI increased gradually, and the average MCI decreased greatly in the southern provinces. (2) At the county scale, the Taihang Mountains, Qinling Mountains, and Hengduan Mountains formed the boundary of China’s single cropping and multiple cropping indices. Dynamic changes in China’s MCI were obvious, and the number of counties with MCI change values lower than 0 increased gradually. Last, (3) natural conditions, nonagricultural process, cultivated land quality, and agricultural intensification demonstrated different degrees of impact on the MCI; in particular, the influence of nonagricultural industries, pesticides, and agricultural plastic film on the MCI proved especially important. Future research should strengthen the existing work on related transformations in farmers’ livelihoods, especially in terms of the return of rural labor force, the body of agricultural production, agricultural ecological issues, and the balance between increased crop production and reduced environmental pollution. In addition, agricultural policy design should pay more attention to cultivated land quality, the farmer who cultivates the land, and the multiple cropping potential of cultivated land.

Localized environmental heterogeneity drives the population differentiation of two endangered and endemic Opisthopappus Shih species

BackgroundClimate heterogeneity not only indirectly shapes the genetic structures of plant populations, but also drives adaptive divergence by impacting demographic dynamics. The variable localized climates and topographic complexity of the Taihang Mountains make them a major natural boundary in Northern China that influences the divergence of organisms distributed across this region. Opisthopappus is an endemic genus of the Taihang Mountains that includes only two spatially partitioned species Opisthopappus longilobus and Opisthopappus taihangensis. For this study, the mechanisms behind the genetic variations in Opisthopappus populations were investigated.ResultsUsing SNP and InDel data coupled with geographic and climatic information, significant genetic differentiation was found to exist either between Opisthopappus populations or two species. All studied populations were divided into two genetic groups with the differentiation of haplotypes between the groups. At approximately 17.44 Ma of the early Miocene, O. taihangensis differentiated from O. longilobus under differing precipitation regimes due to the intensification of the Asian monsoon. Subsequently, intraspecific divergence might be induced by the dramatic climatic transformation from the mid- to late Miocene. During the Pleistocene period, the rapid uplift of the Taihang Mountains coupled with violent climatic oscillations would further promote the diversity of the two species. Following the development of the Taihang Mountains, its complex topography created geographical and ecological heterogeneity, which could lead to spatiotemporal isolation between the Opisthopappus populations. Thus the adaptive divergence might occur within these intraspecific populations in the localized heterogeneous environment of the Taihang Mountains.ConclusionsThe localized environmental events through the integration of small-scale spatial effects impacted the demographic history and differentiation mechanism of Opisthopappus species in the Taihang Mountains. The results provide useful information for us to understand the ecology and evolution of organisms in the mountainous environment from population and species perspective.

Hydrochemical characterization and quality assessment of groundwater in the hilly area of the Taihang Mountains in Henan Province, China.

This study evaluated the quality of groundwater and its suitability for drinking and irrigation in the hilly area of the Taihang Mountains in Henan Province, China. Groundwater samples were collected from 43 unconfined and 20 confined wells and analyzed. The pollution index of groundwater (PIG) was estimated based on the physicochemical parameters, and seven indices, including the sodium adsorption ratio (SAR), sodium percentage (%Na), residual sodium carbonate (RSC), permeability index (PI), magnesium ratio (MR), Kelley's ratio (KR), and corrosivity ratio (CR), were calculated to qualify the groundwater within the research area for irrigation activities. Multivariate statistical techniques were performed to better understand the hydrochemical processes. Chemical analysis showed that the dominant cation and anion were Ca2+ and HCO3-, respectively, and the principal hydrochemical facies was Ca-Mg-HCO3. In terms of pH, total dissolved solids, Na+, Cl-, F-, and SO42-, most samples were well within the limits prescribed by Chinese standards for drinking water quality, but more than half of the unconfined samples exceeded the specified limits for total hardness and nitrate. The PIG values suggested the pollution level was insignificant for all confined water samples and 72.09% of unconfined water samples, but the PIG distribution map showed that the water in the south central part of the study area had low to moderate pollution. According to the computed values of SAR, %Na, RSC, PI, KR, and MR and the results of a salinity diagram, the results further indicated that most of the studied samples were appropriate for irrigation usage. Only the CR values rendered 41.86% of the unconfined samples and 20% of the confined samples unfit for irrigation. Hence, proper measures are needed to resolve the corrosivity problem. Factor analysis resulted in the extraction of 3 factors that explained 81% of the data variability, and the extracted factors pointed towards geogenic factors governing the groundwater quality.

Hydrochemical Characteristics and Formation Mechanism of Strontium-Rich Groundwater in Shijiazhuang, North China Plain

Strontium is a kind of trace element. Groundwater containing strontium is called mineral water when its content reaches a level that is beneficial for human physiology. Some groundwater resources in Shijiazhuang are rich in strontium. In this study, groundwater samples collected from 103 sites were studied for the hydrochemical characteristics of strontium and its formation mechanism in the groundwater system in Shijiazhuang City. The methods of source provenance analysis, factor correlation analysis, and runoff condition analysis were carried out in the study. The results showed that the content of strontium in eastern Shijiazhuang is higher than 0.229 mg/L, with a maximum content of 1.942 mg/L. The source of strontium is the dissolution of strontium-containing minerals in carbonate rock, sheet hemp rock, clastic rock, and granite in the Taihang Mountain area of the Hutuo River Basin. Strontium is positively correlated with total dissolved solids, bicarbonate, calcium magnesium, and free carbon dioxide. The erosion ability of groundwater strengthens the dissolution of strontium, and the geochemical action is mainly due to the dissolution. The enrichment and distribution of strontium are related to the conditions of groundwater runoff. Areas with good runoff conditions and strong mining are low in strontium, while areas with poor runoff conditions have high strontium content.

Barium isotope evidence for recycled crustal materials in the mantle source of continental basalts

To investigate the potential of using Barium (Ba) isotopes to trace recycled crustal materials, we report high-precision Ba isotopic compositions for 22 well-characterized samples of Cenozoic basalts from the Taihang Mountains, North China Craton. The basalts have δ138/134Ba [= (138Ba/134Basample/138Ba/134BaSRM3104a – 1) × 1000] of −0.06‰ to +0.03‰(±0.05‰，2SD), lower than the depleted upper mantle (+0.03‰ to +0.15‰). Because Ba isotope fractionation during basaltic magmatic differentiation is negligible, the light Ba isotopic compositions likely reflect the involvement of isotopically light crustal materials in the mantle source. The Ba isotopic variations, combined with the data of elements and SrNd isotopes of the basalts, indicate that the light Ba isotopic compositions mainly resulted from marine sediments rather than altered oceanic crust. The quantitative modeling using Sr-Nd-Ba isotopic compositions suggests that about 0.5% to 3% of marine sediments were involved in generating the continental basalts. Our study here highlights the potential of using Ba isotopes to trace recycled materials in the mantle.