The Heterogeneity and Its Influencing Factors of Soil Nutrients in Peak-Cluster Depression Areas of Karst Region

By selecting a typical peak-cluster depression area of karst region in Southwest China, we evaluated the effect of land use types and topographic factors on soil nutrients. Grid and line sampling methods were used to sample soil in depression and slope lands respectively, and classical statistical tools were applied to analyze the spatial variability character of soil organic carbon （SOC）, total nitrogen （TN）, total phosphorus （TP）, total potassium （TK）, available nitrogen （AN）, available phosphorus （AP）, available potassium （AK）, pH, and C/N. It was found that land use type was the dominant factor that effected the spatial heterogeneity of SOC, TN, TP, TK, AN, and AP. The content of SOC, TN, and AN decreased with the increase of land use intensity. Due to high fertilizer input, TP and AP in tillage fields were higher than those in the other land use types. TK had no obvious change trend among various land use types. Topographic factors had a significant effect on SOC, TN, TP, AN, AP, AK, and pH. Habitat factor was the dominant factor that effected AK. Altitude factor was the dominant factor for pH. However, all of these factors had no significant effect on C/N. Tillage practice had important effect on soil nutrients loss and soil degradation in the fragile karst ecosystem, and the input of organic manure should be increased in this region.

Evaluation and Quantitative Attribution Analysis of Water Yield Services in the Peak-cluster Depression Basins in Southwest of Guangxi,China

Karst environmental issues have become one of the hot spots in contemporary international geological research. The same problem of water shortage is one of the hot spots of global concern. The peak-cluster depression basins in southwest of Guangxi is an important water connotation and ecological barrier areas in the Pearl River Basin of China. Thus, studying the spatial and temporal variations and the influencing factors of its water yield services is critical to achieve the sustainable development of water resources and ecological environmental protection in this region. As such, this paper uses the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST) model to assess the spatial and temporal variabilities of water yield services and its trends in the peak-cluster depression basins in southwest of Guangxi from 2000 to 2020. This work also integrates precipitation(Pre), reference evapotranspiration(ET), temperature(Tem), digital elevation model(DEM), slope, normalized difference vegetation index(NDVI), land use/land cover(LULC) and soil type to reveal the main factors that influence water yield services with the help of Geodetector. Results show that: 1) in time scale,the total annual water yield in the study area show a fluctuating and increasing trend from 2000 to 2020, with a growth rate of 7.3753 × 10^(8)m^(3)/yr, and its multi-year average water yield was 538.07 mm;2) in spatial pattern, with high yield areas mainly distributed in the south of the study area(mainly including Shangsi County, Pingxiang City, Ningming County, Longzhou County and Jingxi County), and low yield areas mainly distributed in Baise City and Nanning City;3) the dominant factor of water yield within karst and non-karst landforms is not necessarily controlled by precipitation, and the explanation degree of DEM factors in karst areas is significantly higher than that in non-karst areas;4) amongst the climatic factors, Pre, ET and Tem are dominant in the spatial pattern of region water yield capacity. among which Pre has the highest explanatory power for the spatial heterogeneity of annual water production, with q values above0.8, and each driver showed a significant interaction on the spatial distribution of water yield, with Pre exhibiting the strongest interaction with LULC.

The features of soil erosion and soil leakage in karst peak-cluster areas of Southwest China

Through utilizing water flow monitoring, rock scratching, soil wood piles and radionuclide ^(137)Cs tracing in the Longhe karst ecological experimental site(hereinafter referred to"Longhe site"), Pingguo County, Guangxi Province, the features and values of soil erosion and soil leakage in different geomorphologic locations and land uses in the karst peak-cluster depressions are showed clearly. There are four kinds of geomorphologic locations in the karst peak-cluster depression, namely peaks, strip, slopes and depression. The soil leakage modulus in the peaks and strips respectively occupy 92.43% and 96.24% of the total mean soil erosion modulus at experimental sites. On the slope, soil leakage accounted for about 75%. At the bottom of depression, surface water was the main factor of soil erosion, and at last most soil leaked into underground rivers from sinkholes. The total soil erosion modulus and the contribution rates of relative surface soil erosion in regard of peaks, slopes and depressions gradually increased. There are also five major types of land use in the karst peak-cluster depressions, farmland, Kudingcha tea plantations, young Lignum Sappan fields, shrub-grassland and pastures. The soil erosion modulus of slope farmland has the highest value with an increasing trend year by year. But soil erosion modulus of other four land use types decreased by year, which shows the "grain for green" will result in better soil protection. By handling with rocky desertification and ecological rehabilitation in Longhe site, the mean soil erosion modulus of the karst peak-cluster depression has decreased about 80% from 2003 to 2015.

Brain region-specific roles of brain-derived neurotrophic factor in social stress-induced depressive-like behavior

Brain-derived neurotrophic factor is a key factor in stress adaptation and avoidance of a social stress behavioral response.Recent studies have shown that brain-derived neurotrophic factor expression in stressed mice is brain region–specific,particularly involving the corticolimbic system,including the ventral tegmental area,nucleus accumbens,prefrontal cortex,amygdala,and hippocampus.Determining how brain-derived neurotrophic factor participates in stress processing in different brain regions will deepen our understanding of social stress psychopathology.In this review,we discuss the expression and regulation of brain-derived neurotrophic factor in stress-sensitive brain regions closely related to the pathophysiology of depression.We focused on associated molecular pathways and neural circuits,with special attention to the brain-derived neurotrophic factor–tropomyosin receptor kinase B signaling pathway and the ventral tegmental area–nucleus accumbens dopamine circuit.We determined that stress-induced alterations in brain-derived neurotrophic factor levels are likely related to the nature,severity,and duration of stress,especially in the above-mentioned brain regions of the corticolimbic system.Therefore,BDNF might be a biological indicator regulating stress-related processes in various brain regions.

Reservoir controlling differences between consequent faults and antithetic faults in slope area outside of source: A case study of the south-central Wenan slope of Jizhong Depression, Bohai Bay Basin, East China

The control effects of different occurrence faults on oil and gas accumulation and distribution in the outer slope area of oil and gas reservoirs were studied taking the south-central Wen’an slope of the Jizhong depression in the Bohai Bay Basin as an example.Based on 3D seismic data and the distribution of oil and water,the controlling differences between consequent fault and antithetic fault were analyzed and compared from the formation and evolution rule of faults and the formation mechanism of fault traps,including development positions of the consequent fault traps and antithetic fault traps,oil and gas distribution horizon adjusted by fault and formation period of fault traps.The differences between consequent faults and antithetic faults in controlling reservoirs have three main aspects:(1)Consequent fault traps and antithetic fault traps are in different positions,the consequent fault traps are at the segmented growing point in the hanging wall of"hard-linkage"faults,while the antithetic fault traps are developed in the position with the largest throw in the footwall because of tilting action;(2)The two kinds of faults result in different oil and gas distribution vertically,oil and gas adjusted by consequent faults is distributed in a single layer or multi-layers,while oil and gas adjusted by antithetic faults occur in single layers;(3)The two kinds of fault traps are formed in different periods,the consequent fault traps are formed at the time when the related faults enter the stage of"hard-linkage",while the antithetic fault traps are formed at the beginning of the fault active period.

Evaluation of abundant hydrocarbon-generation depressions in the deepwater area of Qiongdongnan Basin,South China Sea

It has been confirmed that the key source rocks of Qiongdongnan Basin are associated with the Yacheng Formation, which was deposited in a transitional marine-continental environment. Because the distribution and evolution patterns of the source rocks in the major depressions are different, it is important to determine the most abundant hydrocarbon-generation depressions in terms of exploration effectiveness. Based on an analysis of organic matter characteristics of the source rocks, in combination with drilling data and seismic data, this paper establishes a model to evaluate the hydrocarbon-generation depressions in the deepwater area of Qiongdongnan Basin. First of all, by using the method of seismic-facies model analysis, the distribution of sedimentary facies was determined. Then, the sedimentary facies were correlated with the organic facies, and the distribution of organic facies was predicted. Meanwhile, the thickness of source rocks for all the depressions was calculated on the basis of a quantitative analysis of seismic velocity and lithology. The relationship between mudstone porosity and vitrinite reflectance（Ro） was used to predict the maturity of source rocks. Second, using the parameters such as thickness and maturity of source rocks, the quantity and intensity of gas generation for Yacheng and Lingshui Formations were calculated. Finally, in combination with the identified hydrocarbon resources, the quantity and intensity of gas generation were used as a guide to establish an evaluation standard for hydrocarbon-generation depressions, which was optimized for the main depressions in the Central Depression Belt. It is proposed that Lingshui, Ledong, Baodao and Changchang Depressions are the most abundant hydrocarbon depressions, whilst Songnan and Beijiao Depressions are rich hydrocarbon depressions. Such an evaluation procedure is beneficial to the next stage of exploration in the deep-water area of Qiongdongnan Basin.

The origin and distribution of natural gas in the frontal uplift area of the Kuqa depression,Tarim Basin

The frontal uplift of the Kuqa depression is an important oil and gas producing area. In this study, the distribution and origin of natural gas were discussed based on natural gas components and isotope data. The main components of natural gas were hydrocarbons with relatively high contents of C2+ component. Most gases were derived from terrestrial source rocks, and some came from marine rocks. The contents of non-hydrocarbon gases were high in the central part of the frontal uplift area and low in the two terminals. The distribution of oil composition was similar to that of natural gas, which was mainly controlled by the types of source rocks. Dry coefficient and maturity of natural gas in the frontal uplift were lower than those of gas in the Kelasu tectonic belt of the Kuqa depression, which was mainly affected by the difference of tectonic movements in both areas. In the frontal uplift, the traps were formed in the early stage and could capture the early formed oil and gas, and structural adjustment was slight in later stages, so the oil and gas could be effectively preserved. Multiperiodic oil and gas filling led to the complex distribution of natural gas.

Study on Depression Development Measures of Karst Rocky Desertification Area in Guizhou Province of China

In view of the current situation and environmental fragility of karst depression in Guizhou,the study proposed measures to utilize and explore it so as to promote economic development of Guizhou depression.

Formation Mechanism of "Drag Depressions" and Irregular Boundaries in Intraplate Deformation

Almost all intraplate caprocks experienced strong deformation during the convergence of microplates, and then disintegrated into many secondary geologic units with the special characters, such as irregular boundaries and particular structural assemblages. In order to understand the formation mechanism of these special phenomena, a rheological experiment on the structural scenery of the Tongling area is carried out. The result shows that the primary regular and uniform boundaries of the Tongling area becomes irregular because of the enclosing and confinement of surrounding geological units in the process of 'compression-shearing-rotation-drag'; simultaneously, two specific 'drag depressions' developed at two opposite corners of the block. The former and the later phenomena can be regarded as a typical regional-scale rheological effect and necessary outcome of intraplate deformation respectively.

Calculation of Depth to Detachment and Its Significance in the Kuqa Depression

The depth to detachment level is a critical factor affecting the quality of structural modeling in fold and thrust belts. There are several detachment levels developed in the Kuqa depression. Based on the excess-area diagram, this paper concerns mainly the calculation of the depth to detachment in the Kuqa depression. The result demonstrates that the detachment levels are situated in different strata in varying zones, such as the Paleogene Kugeliemu Formation, the Paleozoic and the crystalline basement. The calculated depth to detachment level is very helpful for testing whether a structural interpretation is reasonable and for defining the depth of deeper detachment levels which were not discerned in seismic profiles.

Calculation of depth to detachment and its significance in the Kuqa Depression:A discussion

We analyze the excess area and depth to detachment method developed by Epard and Groshong （1993）, and apply it to the sand box model of Ge et al （2004） to illustrate that inadequate consideration will affect the calculation of true depth to detachment. Using the data of Yu et al （2006） to fit linear regression lines, we obtain the depths to detachment of Kela-2, Misikantage anticline and Dongqiu-8 structures, 115.74km, 14.17km, and 75.48km below the reference level （Cretaceous bottom） respectively with the excess area intercept equal to zero. However, the calculation results of depth to detachment in Yu et al （2006） are based on excess area intercept unequal to zero.

Optimizing groundwater recharge plan in North China Plain to repair shallow groundwater depression zone, China

The North China Plain is one of the main grain producing areas in China. However, overexploitation has long been unsustainable since the water supply is mainly from groundwater. Since 2014,the South-to-North Water Diversion Project's central route has been charted to the integrated management of water supply and over-exploitation, which has alleviated the problem to a certain extent. Although the Ministry of Water Resources has made many efforts on groundwater recharge since 2018 most of which have been successful, the recharge has not yet been sufficiently focused on the repair of shallow groundwater depression zones. It still needs further optimization. This paper discusses this particular issue,proposes optimized recharge plan and provides the following recommendations:(1) Seven priority target areas are selected for groundwater recharge in alluvial and proluvial fans in the piedmont plain, and the storage capacity is estimated to be 181.00×10~8 m~3;(2) A recharge of 31.18×10~8 m~3/a is required by 2035 to achieve the repair target;(3) It is proposed to increase the recharge of Hutuo River, Dasha River and Tanghe River to 19.00×10~8 m~3/a and to rehabilitate Gaoliqing-Ningbailong Depression Zone;increase the recharge of Fuyang River, Zhanghe River and Anyang River to 7.05×10~8 m~3/a and rehabilitate Handan Feixiang-Guangping Depression Zone;increase the recharge of Luanhe River by 0.56×10~8 m~3/a and restore Tanghai Depression Zone and Luanan-Leting Depression Zone;moderately reduce the amount of water recharged to North Canal and Yongding River to prevent excessive rebound of groundwater;(4) Recharge through well is implemented on a pilot basis in areas of severe urban ground subsidence and coastal saltwater intrusion;(5) An early warning mechanism for groundwater quality risks in recharge areas is established to ensure the safety. The numerical groundwater flow model also proves reasonable groundwater level restoration in the depression zones by 2035.

Reply to ‘Calculation of depth to detachment and its significance in the Kuqa Depression:A discussion’

This paper mainly replies to the discussion by Li et al （2009） on the calculation of the detachment depths in the Kuqa Depression. We think that viscous material flowing into or out of the cross section can affect the validity of the calculation method, yet the number of detachment levels does not bring any drawbacks to the calculation. In the Kuqa Depression, the salt flow influenced the structural deformation to some extent, and affected slightly the accuracy of the calculated depths of the true detachment levels. However, it does not mean that the calculation method loses effectiveness in the study area. Therefore, the calculation results are still relatively believable.

Human disturbance exacerbated erosion and deposition in the karst peak-cluster depressions during the Ming and Qing dynasties

Under the background of large-scale ecological restoration, China's southwestern karst region has become a hotspot of global vegetation cover “greening” in the past 20 years. However, because of geological constraints, it is difficult to restore the forest landscapes in some areas. It is urgent to understand the impacts of human disturbances during the historical period on the difficult-to-forestation rocky-desertification areas of the karst region in order to guide future afforestation. In this study, we quantified the changes of specific sediment yield in typical karst depressions over the past 500 years by using ^(137)Cs,^(210)Pb, and ^(14)C dating methods in karst depressions, and identified the main human disturbances related to historical erosion and sedimentation by combining with historical data. The results showed that the erosion and sedimentation of the three depressions in 1921–1963 were significantly higher than that in 1963–2021, and the sedimentation rate(0.64–1.33 cm a^(-1)) and the specific sediment yield(2.51–13.11 t ha^(-1)a^(-1)) during Ming and Qing dynasties(1504–1812) were higher than the sedimentation rate(0.26–0.95 cm a^(-1)) and specific sediment yield(0.95–6.99 t ha^(-1)a^(-1)) in the recent century(1921–2021). Reconstruction data and literature from the Ming and Qing dynasties show an empirical link between changes in population, arable land, food, forest area,and deforestation events during the same period. It was found that the population and arable land in Guangxi increased more than three-fold and the forest area decreased significantly in the 17th century after the migration of the Yao ethnic group and the introduction of maize to the region, which may be the main reason for intensifying the erosion of depressions. This study is of great significance to understanding the evolution history of rocky desertification in this region and to answer the potential of afforestation.

Predictive value of intracranial high-density areas in neurological function

BACKGROUND Intracranial high-density areas(HDAs)have attracted considerable attention for predicting clinical outcomes;however,whether HDAs predict worse neurological function and mental health remains controversial and unclear,which requires further investigation.In this prospective study,96 patients with acute ischemic stroke(AIS)who accepted endovascular mechanical thrombectomy(EMT)were included.The enrolled patients underwent cranial computed tomography(CT)examination within 24 hours after EMT.Clinical data in terms of National Institutes of Health Stroke Scale(NIHSS),the 3-month modified Rankin Scale(mRS),self-rating depression scale(SDS),and self-rating anxiety scale(SAS)scores were collected and compared between patients with HDAs and non-HDAs and between patients with good and poor clinical prognosis.Compared to patients without HDAs,patients with HDAs presented severe neurological deficits(admission NIHSS score:18±3 vs 19±4),were more likely to have post-stroke disabilities(mRS<3:35%vs 62%),and suffered more severe depression(SDS score:58±16 vs 64±13)and anxiety disorder(SAS score:52±8 vs 59±10).Compared to patients with a good prognosis,patients with a poor prognosis presented severe neurological deficits(admission NIHSS score:17±4 vs 20±3),were more likely to have HDAs on CT images(64%vs 33%),and suffered more severe depression(SDS score:55±19 vs 65±11)and anxiety(SAS score:50±8 vs 58±12).Multivariate analysis revealed that HDAs were independent nega-tive prognostic factors.CONCLUSION In conclusion,HDAs on CT images predicted poor prognosis and severe depressive and anxiety symptoms in patients with AIS who underwent EMT.

Potentiation of the lateral habenula-ventral tegmental area pathway underlines the susceptibility to depression in mice with chronic pain

Chronic pain often develops severe mood changes such as depression.However,how chronic pain leads to depression remains elusive and the mechanisms determining individuals’responses to depression are largely unexplored.Here we found that depression-like behaviors could only be observed in 67.9%of mice with chronic neuropathic pain,leaving 32.1%of mice with depression resilience.We determined that the spike discharges of the ventral tegmental area(VTA)-projecting lateral habenula(LHb)glutamatergic(Glu)neurons were sequentially increased in sham,resilient and susceptible mice,which consequently inhibited VTA dopaminergic(DA)neurons through a LHbGlu-VTAGABA-VTADA circuit.Furthermore,the LHbGlu-VTADA excitatory inputs were dampened via GABAB receptors in a pre-synaptic manner.Regulation of LHb-VTA pathway largely affected the development of depressive symptoms caused by chronic pain.Our study thus identifies a pivotal role of the LHb-VTA pathway in coupling chronic pain with depression and highlights the activity-dependent contribution of LHbGlu-to-VTADA inhibition in depressive behavioral regulation.

Genesis and Accumulation of Paleo-Oil Reservoir in Dabei Area,Kuqa Depression,Northwest China:Implications for Tight-Gas Accumulation

Paleo-oil reservoir is of great importance to understand hydrocarbon enrichment mechanism and hydrocarbon exploration potential,but is yet poorly investigated in Kuqa Depression.The occurrence of the paleo-oil reservoir in Dabei area was proved by quantitative grain fluorescence(QGF)and fluid inclusion petrography.Development history of the paleo-oil reservoir was reconstructed through:(1)oil-source correlation;(2)time coupling of source rock maturation,porosity evolution and migration pathways.The impact of paleo-oil reservoir on tight-gas accumulation was consequently discussed.Results suggest that considerable oil was accumulated in the K_(1)bs reservoir with paleo oil-water contact in Dabei 2 Well and Dabei 201 Well at 5800 and 6040 m,respectively.Crude oil was primarily sourced from Triassic source rocks with Jurassic source rocks of secondary importance,which was at oil generation window(0.7%–1.1%Ro)during 9–6 and 7.5–5 Ma,respectively.The occurrence of K_(1)bs tight reservoir(porosity<12%)was about 25 Ma,while faults and associated fractures at Kelasue structural belt were developed approximately from 8 to 3.5 Ma.Therefore,the tight oil accumulation was formed during 8–5 Ma.The paleo-oil reservoir in Dabei 1 gas field was destroyed by the evaporation fractionation in later stage.

库车坳陷克深地区白垩系巴什基奇克组致密砂岩裂缝发育特征及地质意义

根据岩心、铸体薄片、激光共聚焦扫描电镜等资料,对库车坳陷克深地区白垩系巴什基奇克组裂缝发育特征及主控因素进行了详细研究,并探讨了其对储层物性和油气聚集效应的影响。研究结果表明:①库车坳陷克深地区白垩系巴什基奇克组为典型的致密砂岩储层,岩石类型以岩屑长石砂岩为主,主要发育剪切缝和张性裂缝,且以高角度缝和直立缝为主,未充填和半充填裂缝占比较大;克深A、克深B气藏裂缝的平面分布差异主要由构造位置和应力演化的不同所导致,其中克深A气藏裂缝有效性优于克深B气藏。②研究区不同构造部位的裂缝密度和有效性存在差异,背斜高点部位裂缝有效性最高,鞍部和翼部近断裂处虽裂缝密度大但有效性较低;砂岩中裂缝有效性高于泥岩;砂、泥岩厚度比与裂缝密度呈非线性关系,当砂岩厚度和泥岩厚度的比值达到6.1时,裂缝密度出现最大值,当比值大于6.1时,裂缝密度逐渐减小。③研究区裂缝的发育可提高致密砂岩储层的渗透率,裂缝网络系统可有效连接低渗透储层,提升了油气的成藏效率、运移能力和富集程度。

Petroleum geology controlled by extensive detachment thinning of continental margin crust: A case study of Baiyun sag in the deep-water area of northern South China Sea

The relationships between crustal stretching and thinning,basin structure and petroleum geology in Baiyun deep-water area were analyzed using large area 3D seismic,gravity,magnetic,ocean bottom seismic(OBS),deep-water exploration wells and integrated ocean drilling program(IODP).During the early syn-rifting period,deep-water area was a half-graben controlled by high angle faults influenced by the brittle extension of upper crust.In the mid syn-rifting period,this area was a broad-deep fault depression controlled by detachment faults undergone brittle-ductile deformation and differentiated extension in the crust.In the late syn-rifting period,this area experienced fault-sag transition due to saucer-shaped rheology change dominated by crustal ductile deformation.A broad-deep fault depression controlled by the large detachment faults penetrating through the crust is an important feature of deep-water basin.The study suggests that the broad-deep Baiyun sag provides great accommodation space for the development of massive deltaic-lacustrine deposition system and hydrocarbon source rocks.The differentiated lithospheric thinning also resulted in the different thermal subsidence during post-rifting period,and then controlled the development of continental shelf break and deep-water reservoir sedimentary environment.The high heat flow background caused by the strong thinning of lithosphere and the rise of mantle source resulted in particularities in the reservoir diagenesis,hydrocarbon generation process and accumulation of deep-water area in northern South China Sea.