Identifying eco-functional zones on the Chinese Loess Plateau using ecosystem service bundles

Optimizing the function of ecosystem services(ESs)is vital for implementing regional ecological management strategies.In this study,we used multi-source data and integrated modelling methods to assess the spatiotemporal variations in eight typical ESs on the Chinese Loess Plateau from 2000 to 2015,including grain production,raw material provision,water conservation,carbon storage service,soil conservation,oxygen production,recreation,and net primary productivity(NPP)services.Then,we divided the ecosystem service bundles(ESBs)according to relationships among the eight ESs,obtaining four types of eco-functional areas at the county(city or banner or district)level based on the spatial clustering of similarities in different ES types.We also identified and assessed the contributions of influencing factors to these eco-functional areas using principal component analysis(PCA)across spatiotemporal scales.We found that the spatiotemporal variations in different ESs were noticeable,with an overall increase in grain production and soil conservation services,no significant change in carbon storage service,and overall decreases in raw material provision,water conservation,oxygen production,recreation,and NPP services.From 2000 to 2015,the number of significant synergistic ES pairs decreased,while that of significant trade-off pairs increased.To the changes of ESBs in the eco-functional areas,the results indicated that the indirect loss of these ESs from forest and grassland due to urban expansion should be reduced in ecological development area(ESB 2)and multi ecological functional area(ESB 3).Meanwhile,crop planting structures and planting densities should be adjusted to reduce ES trade-offs associated with water conservation service in grain-producing area(ESB 4).Lastly,ESB-based ecofunctional zoning can be used to improve ecological restoration management strategies and optimize ecological compensation schemes in ecologically fragile area(ESB 1).

Vegetation and environmental changes in western Chinese Loess Plateau since 13.0 ka BP

Pollen records from the Chinese Loess Plateau revealed a detailed history of vegetation variation and associated climate changes during the last 13.0 ka BP. Before 12.1 ka BP, steppe or desert-steppe vegetation dominated landscape then was replaced by a coniferous forest under a generally wet climate （12.1-11.0 ka BP）. The vegetation was deteriorated into steppe landscape and further into a desert-steppe landscape between 11.0 and 9.8 ka BP. After a brief episode of a cool and wet climate （9.8-9.6 ka BP）, a relatively mild and dry condition prevailed during the early Holocene （9.6-7.6 ka BP）. The most favourable climate of warm and humid period occurred during mid-Holocene （7.6-4.0 ka BP） marked by forest-steppe landscape and vegetation alternatively changed between steppe and desert-steppe from -4.0 to -1.0 ka BP.

Chronology of the Holocene loess-paleosol section and its deposition and pedogenesis on the south of Chinese Loess Plateau

Optically stimulated luminescence （OSL） dating for polymlneral fine-grained loess samples, collected in Laoguantai （LGT） section on the south of the Chinese Loess Plateau, was made by application of single-aliquot regenerative-dose （SAR） protocol. A ＇Double-SAW procedure in which aliquots are subjected to both infrared （IR） and blue stimulations was used and two sets of equivalent dose （De） determinations were produced and assumed to relate predominantly to feldspathic and quartz fine grain populations respectively, The OSL ages estimated from IRSL signals are smaller than those estimated from [post-IR] OSL signals due to the anomalous fading of feldspar IR signals, based on fading experiment, The young ages of the samples near ground surface may be originated from the post-depositional disturbance by the intensifying humanity＇s cultivation since 3.0 ka BP in the Guanzhong Basin, south of the Chinese Loess Plateau. Based on OSL dating, as well as field observations and stratigraphic correlation, we determine the chronology of the LGT Ioess-paleosol sequence. In combination with climate proxy records, it is indicated that aeolian loess deposition and pedogenesis underwent polyphase changes during the Holocene, likely to have been driven by shifts in the East Asian monsoon. This suggests that aeolian loess deposition is episodic and highly variable, with contributions from non-aeolian processes such as alluvial deposition found in the area.

Reliability of Relative Paleointensity Recorded in Chinese Loess-Paleosol Sediments

A detailed paleomagnetic and rock-magnetic investigation spanning loess L7 to paleosol S8 has been carried out at the Baoji and Xifeng sections. Results of anisotropy of magnetic susceptibility confirm that the studied loess-paleosol sediments retain primary sedimentary fabrics. Stepwise thermal demagnetization shows that two well-defined magnetization components can be isolated from both loess and paleosol specimens. A low-temperature component, isolated between 100°C and 200°C, is consistent with the present geomagnetic field direction, and a high-temperature component, isolated between 200-300°C and 620-680°C, includes clearly normal and reversed polarities. Isothermal remanent magnetization and thermomagnetic analyses indicate that characteristic remanent magnetization is mainly carried by magnetite and hematite. The Day plot, together with the stratigraphic variations of rock-magnetic parameters, shows that the uniformity of magnetic mineralogy and grain size fulfills the criteria for relative paleointensity （RPI） studies. RPI records have been constructed using natural remanent magnetization （NRM） intensity after thermal demagnetization at 300°C normalized by low-frequency magnetic susceptibility （NRM 300 /χ）. The results show that the RPI record from the Baoji section, where pedogenesis is quite weak, is compatible with the stacked PISO-1500 paleointensity record, suggesting that it might reflect the paleointensity variation of the geomagnetic field. The RPI record from the Xifeng section, where pedogenesis is rather strong, indicates a clear dissimilarity with the stacked PISO-1500 paleointensity record, implying that it does not reflect the paleointensity variation of the geomagnetic field. Our new results show that the NRM 300 /χ from the strongly pedogenetic paleosols does not completely eliminate the pedogenetic （climatic） influence, so it might be unsuitable for a reliable paleointensity study.

Dynamics of NDVI and its influencing factors in the Chinese Loess Plateau during 2002-2018

Understanding the spatio-temporal changes of vegetation and its climatic control factors can provide an important theoretical basis for the protection and restoration of eco-environments.In this study,we analyzed the normalized difference vegetation index(NDVI)in the Chinese Loess Plateau(CLP)from 2002 to 2018 via trend analysis,stability analysis,and Mann-Kendall mutation test to investigate the change of vegetation.In addition,we also used the skewness analysis and correlation analysis to explore the contribution of climate change and human activities on regional vegetation changes.The results indicated that the overall increasing trend of NDVI from 2002 to 2018 was significant The areas showing increased NDVI were mainly distributed in the south-eastern CLP and the irrigation districts of the Yellow River to the north and west of the CLP,while the areas showing decreased NDVl were concentrated in the desert of the westem Ordos Plateau,Longzhong Loess Plateau,and the built-up and adjacent areas.Precipitation was the dominant factor contributing to vegetation growth in the CLP,while vegetation was less dependent onprecipitation in the irigation districts.The increasement of NDVI has led to a prolonged responsetime of vegetation to water stress and a lag effect of less than two months in the CLP.The effect of temperature on NDVI was not significant;significant negative correlations between NDVI and temperature were found only in the desert,the Guanzhong Plain,the southem Liupan Mountains,and the southeastem Taihang Mountains,owing to high temperatures,urban heat islands,and large cloud cover in mountainous areas.Affected by the"Grain for Green Program"(GGP),NDVIin the CLP increased from 2002 to 2018;however,the increasing trends of NDNI for differentvegetation cover types were significantly different owing to the difference in background status.The increasing contribution rate of NDVI in the CLP mainly came from crops and steppes.Urban not only led to the destruction of vegetation but also had radiation effect causing negative impact of NDVI around the cities.This resulted in the aggravation of the negative bias of NDVI with time in the CLP.The results provide a long-term perspective for regional vegetation protection and utilization in the CLP.

Failure mechanisms and risk mitigation of check dams on the Chinese Loess Plateau: A case study at the Gutun Gully

Loess is long-term aeolian dust deposition, characterized by loose structure, concentrated participle distribution and unstable mineral composition, and thus easy to cause extensive collapsibility and have general water sensitivity. To reveal the difference in water sensitivity between naturally intact(NI) loess and mechanically compacted(MC) loess used for the check dam, the transient water release and imbibition method(TRIM) was used to acquire the suction stress–expanded hydraulic characteristic curves for the NI and MC loess and explore possible approaches for formulating the potential of loess water sensitivity. Based on the Local Field of Safety(LFS) associated with slope stability, we constructed a finite element model of a check dam to depict its failure processes under different rainfall scenarios. The results revealed the strong water sensitivity in NI loess, while the MC loess retained a certain water-sensitive potential. This capacity depends on the ‘water sensitivity coefficient’ obtained from the suction-stress characteristic curve,which better presented the deformation potential of the two loess samples at different water content levels. In the context of LFS, we identified two failure patterns in the dam body that were involved in loess water sensitivity under hydromechanical conditions: rainfall erosion-induced shallow mudflow failure, and preferential-infiltration progressive failure. These patterns may provide new insights into dam-breakage mechanisms and potential chain effects of check dams on the Chinese Loess Plateau from the perspective of soil–water interactions, which is vital for predicting the position and timing of check dam failure, and mitigating risks.

Spatial-temporal pattern and formation mechanism of county urbanization on the Chinese Loess Plateau

Urbanization is a comprehensive and complex socioeconomic phenomenon that plays an influential role in promoting global socioeconomic development.The Loess Plateau region is an important part of the China’s ecological security pattern,and occupies an important position in the implementation of China’s new-type urbanization strategy and the realization of the urban dream.The characteristics of the staged changes and regional differentiation of urbanization in the area from 1990 to 2018 were studied with focus on regions and subregions by selecting 341 county-level administrative units on the Chinese Loess Plateau as the research area,and employing partition analysis and geographic detector methods.This revealed the formation mechanism of the spatial differentiation pattern of urbanization on the Loess Plateau.We found that the urbanization of the Loess Plateau,previously in a slow growth phase,entered the accelerated development phase,presenting a macro pattern of high rates of urbanization in central and eastern areas and low rates in western areas.The formation of the regional differentiation patterns of urbanization on the Loess Plateau were the combined results of natural geographical and socioeconomic factors.Among these factors,the interaction of any two factors had a stronger impact on regional urbanization patterns than a single factor,which was specifically manifested as nonlinear or bi-factor enhancement effects.The findings of this paper may provide a theoretical reference and scientific basis for the scientific promotion of healthy urbanization on the Chinese Loess Plateau and the ecologically fragile areas of developing countries around the world.

A New Model for Correlation between the Marine Benthic Oxygen Isotope and Red Clay Magnetic Susceptibility on the Chinese Loess Plateau

Objective Aeolian sediments on the Chinese Loess Plateau contain some of the best continental archives of palaeoclimate change in the Late Cenozoic. The consensus that alternating MS in loess-paleosols in China was due to the strengthening and weakening of the East Asian palaeomonsoon provides an excellent climate record when correlated with global ice volume. Significantly, new basal dates from the red clay underlying the loess-paleosol sequence indicate that wind-blown dust began to accumulate on the Chinese Loess Plateau at least 22 million years ago. There are differences of opinion,

Paleoenvironmental Record from Wuqi Paleolake in Northern Chinese Loess Plateau

Jinding core(ZK04,36°47′35.36″N,108°19′05.24″E)is located in the northern area of Luohe river basin,northern Chinese loess plateau,lying to the southeast of Wuqi County about 20 km.The total depth of Core ZK04 is 92.20

Formation mechanisms and remediation techniques for low-efficiency artificial shelter forests on the Chinese Loess Plateau

The construction of artificial shelter forests(ASFs)has resulted in substantial ecological,economic,and societal benefits to the Chinese Loess Plateau(CLP).However,the health and benefits of ASFs are being increasingly threatened by the formation of low-efficiency artificial shelter forests(LEASFs).In this study,LEASFs are systematically analyzed in terms of their status,formation mechanisms,and developmental obstacles.The key restoration techniques and schemes were summarized to improve the quality and efficiency of LEASFs.LEASFs are formed by relatively complex mechanisms,but they arise mainly due to poor habitat conditions,improper tree species selections,mismatch between stands and habitat,extensive forest management measures,and human interferences.The restoration and improvement of LEASFs are hindered by water deficits,mismatch between stands and habitat,single management purpose,and low efficiency.LEASFs are becoming more complex due to their wide range,the challenges associated with their restoration,and insufficient technological measures for their restoration.The key techniques of the quality and efficiency improvement of LEASFs include basic forest tending methods,near-natural restoration,multifunction-oriented improvement,and systematic restoration.An understanding on the formation mechanisms of LEASFs and a scientific approach toward their restoration are urgently needed and critical for the ecological protection and high-quality development of LEASFs on the CLP.Based on these analyses,we recommend strengthening the monitoring and supervision of LEASFs,considering the bearing capacity of regional water resources,implementing multiple restoration techniques,promoting multifunction-oriented ecological development,and exploring new management concepts to achieve the sustainable development of ASFs on the CLP.

Spatial-temporal Characteristics of Holocene Paleosols in the Chinese Loess Plateau and Paleoclimatic Significance

The evolution of Holocene climate was investigated using grain size and magnetic susceptibility of the Holocene paleosols from Baicaoyuan(BCY),Xifeng(XF) and Linyou(LY) sections in the northwest,central and southern Chinese Loess Plateau(CLP).The results show that the Holocene in the B CY,XF and LY paleosol sections could be divided into three phases:during the early Holocene(11.8-10.5 kyr B.P.),increased magnetic susceptibility(χ) and frequency-dependent magnetic susceptibility(χ) and decreased median grain size(Md) indicate that the East Asian Summer Monsoon(EASM) has become more intense and the climate has changed from cold to warm.During the middle Holocene(10.5-5.0 kyr B.P.),the values of χ,χand 2-5 μm grain-size fraction(GT2/5) are higher and Md and 30-63 μm grain-size fraction(GT3 0/6 3) are the lowest,which reflect a warm and humid regional climate.At~8.0 kyr B.P.,there was a transient dry-cold climatic spike corresponding to a Heinrich Event,the cold event was likely due to the collapse of the Laurentide ice sheet.During the late Holocene(5.0-0 kyr B.P.),χ and χvalues are the lowest,while Md and GT30/63 are high,as proxies of a weakened EASM,when the dry-cold climate prevailed in the region.Decreased irradiance since 5.0 kyr B.P.may have caused climatic cooling and drying.Spatially,the increased main peak values and skewness from BCY,XF to LY sections show that the grain size became fine,the East Asian Winter Monsoon(EAWM) reduced,and climate was warmer and wetter from northwest to southeast.In addition,Md can be used as alternative proxy for EAWM,while χis positive with the intensity of EASM under semiarid climate conditions in CLP.

Large-scale extraction of check dams and silted fields on the Chinese loess plateau using ensemble learning models

Check dams have been widely constructed in the Chinese Loess Plateau and has played an important role in controlling soil loss during last 70 years.However,the large-scale and automatic mapping of the check dams and the resulting silted fields are lacking.In this study,we present a novel methodological framework to extract silted fields and to estimate the location of the check dams at a pixel level in the Wuding River catchment by remote sensing and ensemble learning models.The random under-sampling method and 23 features were used to train and validate three ensemble learning models,namely Random Forest,Extreme Gradient Boosting and EasyEnsemble,based on a large number of samples.The established optimal model was then applied to the whole study area to map check dams and silted fields.Our results indicate that the imbalance ratio of the samples has a significant impact on the performance of the models.Validation of the results on the testing set show that the F1-score of silted fields of three models is higher than 0.75 at the pixel level.Finally,we produced a map of silted fields and check dams at 10 m-spatial resolution by the optimal model with an accuracy of ca.90%at the object level.The proposed framework can be used for the large-scale and high-precision mapping of check dams and silted fields,which is of great significance for the monitoring and management of the dynamics of check dams and the quantitative evaluation of their eco-environmental benefits.

Climatic Fluctuation of Marine Isotope Stage 9: A Case Study in the Southern Margin of the Chinese Loess Plateau

Marine Isotope Stages(MIS) 9 has been proposed as an analog for the present warm period. However, detailed studies of this geological time period are rare in loess-paleosol sequence. In the Chinese Loess Plateau(CLP), the corresponding stratum is the third paleosol layer(S3). Here, we report the terrestrial reconstruction of climatic fluctuations during MIS 9 by analyzing the paleo-climate indexes of S3 with high sampling density. Our results showed that:(1) During the period of MIS 9, the main climatic sub-cycle was 29 ka;(2) MIS 9 could be divided into five sections, MIS 9a, 9b, 9c, 9d, and 9e. Among them, MIS 9a, 9c, and 9e were warm stages, while MIS 9b and 9d were cool intervals;and 3) There were also three swift warm-wet events and one cool-dry event, which occurred around 332 –331, 324–323, 311–310, and 331–329 ka BP, respectively. The overall trend of paleo-climate fluctuation correlated approximately with SPECMAP, LR04 stack and Iberian margin deep-sea cores. This study suggested that the paleosol records in the southern margin of the CLP have global significance and contain more detailed climatic signals than marine deposits.

New eolian red clay sequence on the western Chinese Loess Plateau linked to onset of Asian desertification about 25 Ma ago

The expansion of inland Asia deserts has considerably influenced the environmental, social and economic activities in Asia. Aridification of inland Asia, especially timing of the initiation of Asian desertification, is a contentious topic in paleoclimatology. Late Cenozoic eolian loess-red clay sequences on the Chinese Loess Plateau, which possess abundant paleoclimatic and paleo-environmental information, can be regarded as an indicator of inland Asia desertification. Here we present a detailed magnetostratigraphic investigation of a new red clay sequence about 654 m in Zhuanglang located at the western Chinese Loess Plateau. Sedimentological, geochemical, mineralogical, and quartz morphological lines of evidence show that the red clay is of eolian origin. Magnetostratigraphic correlations indicate that this core sequence spans from 25.6 to 4.8 Ma, and typical eolian red clay appears as early as 25 Ma. This extends the lower limit of the red clay on the Chinese Loess Plateau from the previously thought early Miocene back into the late Oligocene. This new red clay record further implies that the inland Asia desertification was initiated at least by the late Oligocene. This sequence provides a unique high-resolution geological record for understanding the inland Asia desertification process since the late Oligocene.

High-resolution anisotropy of magnetic susceptibility record in the central Chinese Loess Plateau and its paleoenvironment implications

We analyze high-resolution anisotropy of magnetic susceptibility (AMS) of the loess-paleosol successions at Luochuan, central Chinese Loess Plateau, in order to investigate the AMS characteristics and their climatic implications. Our results indicate a normal sedimentary magnetic fabric for almost of all samples, characterized by minimum susceptibility axes grouped in an almost vertical direction. Magnetic foliation and anisotropy degree show upwards decreasing trend due to decreasing post-depositional compaction. Magnetic lineations show no preferred directions and thus cannot indicate paleowind patterns. AMS parameters at Luochuan are controlled by particle size, pedogenesis, and sedimentary compaction. The high peaks of magnetic foliation and anisotropy degree of L2, L3, L6, L9, and L15 correspond to the coarse particle sizes of these loess beds, indicating the grain-size dependence of AMS.

Autumn Daily Characteristics of Land Surface Heat and Water Exchange over the Loess Plateau Mesa in China

The Loess Plateau, located in northern China, has a significant impact on the climate and ecosystem evolvement over the East Asian continent. In this paper, the preliminary autumn daily characteristics of land surface energy and water exchange over the Chinese Loess Plateau mesa region are evaluated by using data collected during the Loess Plateau land-atmosphere interaction pilot experiment （LOPEX04）, which was conducted from 25 August to 12 September 2004 near Pingliang city, Gansu Province of China. The experiment was carried out in a region with a typical landscape of the Chinese Loess Plateau, known as ＂loess mesa＂. The experiment＇s field land utilizations were cornfield and fallow farmland, with the fallow field later used for rotating winter wheat. The autumn daily characteristics of heat and water exchange evidently differed between the mesa cornfield and fallow, and the imbalance term of the surface energy was large. This is discussed in terms of sampling errors in the flux observations-footprint; energy storage terms of soil and vegetation layers; contribution from air advections; and low and high frequency loss of turbulent fluxes and instruments bias. Comparison of energy components between the mesa cornfield and the lowland cornfield did not reveal any obvious difference. Inadequacies of the field observation equipment and experimental design emerged during the study, and some new research topics have emerged from this pilot experiment for future investigation.

Distribution, failure risk and reinforcement necessity of check-dams on the Loess Plateau: a review

Check-dams are the most important measure to control the soil and water loss in highly erodible catchments on the Chinese Loess Plateau.Based on the data of check-dams from 1950 to 2014,our study roundly analyzed the regional distribution,function and the problems of check-dams on the Loess Plateau.A total of 17,094 check-dams with a storage capacity of over 100,000 m^(3) and an average density of 0.027 counts km^(-2) were installed on the Loess Plateau.Check-dams’densities varied greatly in the Qinghai Province,Gansu Province,Ningxia Hui Autonomous Region,Inner Mongolia Autonomous Region,Shaanxi Province,Shanxi Province and Henan Province.The highest density of check-dams reached 0.088 counts km^(-2) in Shaanxi Province,whereas the lowest density of check-dams was only 0.005 counts km^(-2) in Qinghai Province.However,after decades of operation,3025 large check-dams and 2257 medium check dams are dangerous and have security risks,which are seriously threatening downstream safety.The dangerous rate of checkdams is high.Specifically,the check-dams in Shanxi and Qinghai Province have the highest dangerous rates,with both exceeding 53%.Therefore,there is an urgent need for carrying out reinforcement of the dangerous check-dams.The results are helpful to policymakers to extend and develop check-dams.

Vertical Atmospheric Structure of the Late Summer Clear Days over the East Gansu Loess Plateau in China

In this paper, by using the sounding data collected in LOPEX05, we have analyzed the vertical atmospheric structure and boundary layer characteristics of temperature and humidity in the late summer over the east Gansu loess plateau. The results show that the bottom of the stratosphere is at about 16 500 m and varies between 14 000 m and 18 000 m above the ground. The center of the westerly jet is located between 8300 m and 14 300 m above the ground and its direction moves between 260~ and 305~. There is an inverse humidity layer at about 3000 m height above the ground. The maximum of the air temperature occurs at 1700 LST in the layer below 800 m above the ground. The inversion layer is relatively thick. The time that the maximum of the vapor occurs is not the same for different layers. The depth of the atmospheric boundary layer can reach about 1000 m and the depth of the stable boundary layer can be 650 m.

Progress of loess research in China

Progress in Chinese loess research made in recent 15 years was introduced in this paper, including mainly distribution and paleoenvironment significance of Chinese loess, new development of loess formation age, red-brown paleosol types and environmental change, loess-paleosol sequence and climate cycles, monsoon strength change during last interglacial and last glacial periods in the Loess Plateau, climate events, and source areas of loess and material.

Chemical weathering processes in the Chinese Loess Plateau

Covered by erodible loess and affected by significant seasonal climate variations,chemical weathering in the Chinese Loess Plateau(abbreviated as CLP)has important effects on the hydrochemistry of the Yellow River and the global carbon cycle.However,chemical weathering processes in the CLP are still unclear.Based on 296 river water samples in the CLP in the different seasons,hydrochemistry,weathering processes,and their controlling factors were revealed.River waters in the CLP exhibited slightly alkalinity(pH=8.4±0.5)with much high total dissolved solids(TDS)values(691±813 mg/L).The water types of river water in the CLP were primarily SO_(4)^(2-)-Cl^(-)-Na^(+),HCO_(3)^(-)-Ca^(2+)-Mg^(2+),and SO_(4)^(2-)-Cl^(-)-Ca^(2+)-Mg^(2+).According to the forward model,evaporite dissolution has the largest contribution(55.1%±0.2%)to riverine solutes in the CLP,then followed by carbonate weathering(35.6%±0.2%)and silicate weathering(6.5%±0.1%).For spatio-temporal variations,the contribution of evaporite dissolution in the CLP decreased from northwest to southeast with higher proportion in the dry season,carbonate weathering increased from northwest to southeast with a higher proportion in the wet season,and silicate weathering showed minor spatio-temporal variations.Ca^(2+)and Mg^(2+)were affected by carbonate precipitation and/or incongruent calcite dissolution,and about 50%of samples exhibited cation exchange reactions.The physical erosion rate in the CLP,which was 372±293 t·km^(-2)·yr^(-1),varied greatly and was greater than those of other worldwide rivers.Chemical weathering rates in the CLP showed an increasing trend southward.During the wet season,high runoff led to the release of evaporite and carbonate from loess,while the interfacial reaction kinetic limited the increase of the silicate weathering rates.The CO_(2)consumption budget by carbonate weathering(6.1×10^(10)mol/yr)and silicate weathering(1.6×10^(10)mol/yr)in the CLP accounted for 0.29%and 0.08%of the global carbon cycle,respectively.Meanwhile,the weathering proportion by sulfuric acids was relatively high with a CO_(2)release flux of 6.5×10^(9)mol/yr.By compiling the data,we propose that the interfacial reaction kinetic and runoff control CO_(2)consumption rate by silicate and carbonate weathering,respectively.These results contribute to the understanding of modern weathering processes of loess in the CLP,thus helping to deduce the environmental and climatic evolution of the basin.