Reflections on the “Green Development Mode in Southwest China” and Implementation Path——A Case Study on PetroChina Southwest Oil and Gasfield Company

Introduction As the world’s largest developing country, China will maintain a rigid growth in energy consumption for a long time to come [1-3]. Natural gas, the cleanest and low-carbon fossil energy source, plays an essential role in the country’s achieving its strategic goals of “carbon peak and carbon neutrality”(hereinafter referred to as the “dual carbon” goals).

Study on Soil Erosion Model Under Different Slopes in Southwest Karst Mountain Area

The aim was to further research soil erosion characteristics and accurately predict soil erosion amount in karst areas. Based on field surveys and research achievements available, yellow soils, which are widely distributed, were chosen as test soil samples and slope, rain intensity, vegetation coverage and bare-rock ratio were taken as soil erosion factors. Artificial rain simulation instruments （needle-type） were made use of to simulate correlation of rain intensity, vegetation coverage, and bare-rock ratio with soil erosion quantity. Furthermore, multiple-factor linear regression analysis, stepwise regression analysis and multiple-factor non-linear regression analy- sis were made to establish a multiple-factor formula of soil erosion modulus with dif- ferent slopes and select regression models with high correlation coefficients. The re- sults show that a non-linear regression model reached extremely significant level or significant level （0.692〈FF〈0.988） and linear regression model achieved significant lev- el （0.523〈FF〈0.634）. The effects of erosion modulus changed from decreasing to in- creasing and the erosion factors from high to low were rain intensity, vegetation cov- erage and bare-rock ratio when slope gradient was at 6~, 16~, 26~ and 36~. The mod- el is of high accuracy for predicting gentle slope and abtupt slope, which reveals correlation of erosion modulus with erosion factors in karst areas.

Surface Morphology of Soil Cracks in Yuanmou Dry-hot Valley Region,Southwest China

Surface morphology of soil cracks is one of the important factors influencing the water evaporation rate in cracked soil in Yuanmou Dry-hot Valley Region,Southwest China. Quantitative study of the complicated surface morphology of soil cracks is a prerequisite for further studies of soil-cracking mechanisms. The present paper establishes a quantitative indicator system by application of concepts and methods originating from Fractal Geometry and Network Analysis. These indicators can effectively express the complicated features of soil-crack network structure. Furthermore,a series of values related to soil-crack morphology was obtained by image processing on field photos of soil-crack quads,and gradation criteria for the degree of development of soil cracks were determined. Finally,the changes in values of the morphological indicators under different degrees of development were analyzed in detail. Our results indicate that (1) the degree of development of soil cracks can be divided into five grades,i.e.,feeble development,slight development,medium development,intensive development and extremely intensive development; (2) the values of the indicators change predictably with increasing degree of development of soil cracks. The area density (Dc) increases,and both the area-weighted mean ratio of crack area to perimeter (AWMARP),which reflects the intensity of cracking,and the index r,which is related to the connectivity of a soil crack,grow uniformly (albeit with different forms). AWMRAP increases at a geometric rate while r shows logarithm-mic growth,indicating a gradual increase in theconnectivity of a soil crack. Nevertheless,the area-weighted mean of soil-crack fractal dimension (AWMFRAC) shows a decreasing trend,indicating a gradual decline in the complexity of cracks as area density increases.

Simulation of Morphological Development of Soil Cracks in Yuanmou Dry-hot Valley Region, Southwest China

Soil cracking is an important process influencing water and solutes transport in the Yuanmou Dry-hot Valley region of Southwest China. Studying the morphological development of soil cracks helps to further reveal the close relationship between the soil cracking process and water movement in such semi-arid regions. Here we report regular changes on surface morphology of soil cracks with decreasing water in four different soils (Typ-Ustic Ferrisols,Ver-Ustic Ferrisols,Tru-Ustic Vertisols and Typ-Ustic Vertisols) through simulation experiments. Our results indicate the following: 1) Different soils ultimately have different development degrees of soil cracks,according to their various values of crack area density. Soil cracks in Typ-Ustic Ferrisols can only develop to the feeble degree,while those in the other three soils are capable of developing into the intensive degree,and even into the extremely intensive degree. 2) Soil crack complexity,as expressed by the value of the area-weighted mean of crack fractal dimension (AWMFRAC),is found to continuously decrease as a whole through the whole cracking process in all the studied soils. 3) Soil crack connectivity shows a uniform trend in the studied soils,that is to say,connectivity gradually increases with soil crack development.

Characteristics of heavy metals in soils under different land use in a typical karst area, Southwest China

This study investigated the distribution of six pollutant elements(Cr, Cu, Pb, Zn, Cd, and As), and their relationship to soil organic carbon(SOC) in five soil profiles in the Puding area. Results show SOC content decreased exponentially to the depth of soil profiles; the vertical distribution patterns of SOC in soil profiles were partially controlled by land use. The concentrations of these pollutant elements in most soils were lower than background values, indicating that the local soil was less likely to be contaminated by foreign inputs. Geo-accumulation index values of these elements in most soil samples were less than 1, suggesting that the soil of this area may not be polluted. The concentrations of Cr, Cu, As, and Zn in soils from all land use types were significantly negatively correlated with SOC contents. Geochemical approaches confirmed that the soil of this area was less influenced by pollutant elements.

Genetic mechanism and development of the unsteady Sarvak play of the Azadegan oil field,southwest of Iran

The upper Cretaceous Sarvak reservoir in the Azadegan oil field of southwest Iran has its oil–water contact nearly horizontal from the north to the center and dips steeply from the center to the south.The purpose of this paper is to interpret this abnormal reservoir feature by examining the accumulation elements,characteristics,and evolution based on the 3D seismic,coring,and well logging data.Generally,in the field,the Sarvak reservoir is massive and vertically heterogeneous,and impermeable interlayers are rare.The distribution of petrophysical properties is mainly dominated by the depositional paleogeomorphology and degrades from north to south laterally.The source is the lower Cretaceous Kazhdumi Formation of the eastern Dezful sag,and the seal is the muddy dense limestone of the Cenozoic Gurpi and Pebdeh Formations.Combined with the trap evolution,the accumulation evolution can be summarized as follows： the Sarvak play became a paleo-anticlinal trap in the Alpine tectonic activity after the late Cretaceous（96 Ma） and then was relatively peaceful in the later long geologic period.The Kazhdumi Formation entered in the oil window at the early Miocene（12–10 Ma） and charged the Sarvak bed,thus forming the paleo-reservoir.Impacted by the ZagrosOrogeny,the paleo-reservoir trap experienced a strong secondary deformation in the late Pliocene（4 Ma）,which shows as the paleo-trap shrank dramatically and the prelow southern area uplifted and formed a new secondary anticline trap,hence evolving to the current two structural highs with the south point（secondary trap） higher than the north（paleo-trap）.The trap deformation broke the paleoreservoir kinetic equilibrium and caused the secondary reservoir adjustment.The upper seal prevented vertical oil dissipation,and thus,the migration is mainly in interior Sarvak bed from northern paleo-reservoir to the southern secondary trap.The strong reservoir heterogeneity and the degradation trend of reservoir properties along migration path（north to south） made the reservoir readjustment extremely slow,plus the short and insufficient re-balance time,making the Sarvak form an ‘‘unsteady reservoir＇＇which is still in the readjustment process and has not reached a new balance state.The current abnormal oil–water contact versus the trap evolutionary trend indicates the secondary readjustment is still in its early stage and has only impacted part of paleo-reservoir.Consequently,not all of the reservoir is dominated by the current structure,and some parts still stay at the paleo-reservoir form.From the overview above,we suggest the following for the future development： In the northern structural high,the field development should be focused on the original paleoreservoir zone.In the southern structural high,compared with the secondary reservoir of the Sarvak with the tilted oil–water contact and huge geologic uncertainty,the lower sandstone reservoirs are more reliable and could be developed first,and then the deployment optimized of the upper Sarvak after obtaining sufficient geological data.By the hints of the similar reservoir characteristics and tectonic inheritance with Sarvak,the lower Cretaceous Fahliyancarbonate reservoir is also proved to be an unsteady reservoir with a tilted oil–water contact.

Characteristics and distributions of humic acids in two soil profiles of the southwest China Karst area

Characteristics and distributions of humic acid(HA) and soil organic matter(SOM) in a yellow soil profile and a limestone soil profile of the southwest China Karst area were systematically investigated to reveal their evolutions in different soils of the study area. The results showed that characteristics and distribution of SOM along the two soil profiles were notably different. Total organic carbon(TOC) contents of soil samples decreased just slightly along the limestone soil profile but sharply along the yellow soil profile. TOCs of the limestone soils were significantly higher than those of the corresponding yellow soils, and C/N ratios of SOMs showed a similar variation trend to that of TOCs, indicating that SOM can be better conserved in the limestone soil than in the yellow soil. The soil humic acids were exhaustively extracted and further fractionated according to their apparent molecular weights using ultrafiltration techniques to explore underlying conservation mechanisms. The result showed that C/N ratios of HAs from different limestone soil layers were relatively stable and that large molecular HA fractions predominated the bulk HA of the top soil, indicating that HA in the limestone profile was protected while bio and chemical degradations were retarded. Combined with organic elements contents and mineral contents of two soils, weconcluded that high calcium contents in limestone soils may play a key role in SOM conservation by forming complexation compounds with HAs or/and enclosing SOMs with hypergene CaCO_3 precipitation.

Chemical constituents in the essential oil of the endemic plant Cotula cinerea (Del.) from the southwest of Algeria

Objective: To extract and identify the main constituents of the essential oil of Cotula cinerea(Del.)(Asteraceae family) from southwest of Algeria.Methods: The essential oils obtained by hydrodistillation, from the aerial parts of the endemic plant Cotula cinerea which was collected in the region of Sahara from southwest of Algeria, were analyzed by gas chromatography-mass spectrometry.Results: A total of 33 compounds were identified representing 98.66% of the oil. The main compounds were(E)-citral(24.01%), limonene epoxide cis-(18.26%), thymol methyl ether(15.04%), carvacrol(15.03%), trans-carveol(13.79%), carvone(3.06%) and trans-piperitol(2.54%).Conclusions: The main constituents in essential oil of the aerial part of the plant from southwest of Algeria were different from that collected from southeast of Algeria or in Morocco.

Boehmeria nivea var. strigosa (Urticaceae), a new variety from Southwest China

Boehmeria nivea var.strigosa Zeng Y.Wu&Y.Zhao,a new variety of B.nivea(Urticaceae)from Southwest China,is here described based on evidence from morphology and molecular phylogeny.This new variety is mainly characterized by its green abaxial leaf blade,partly connate stipules,and densely patent strigose hairs on stems and potioles.The phylogenetic analysis based on rbc L,nrDNA and rbc L+nrDNA datasets,revealed that all individuals of B.nivea var.strigosa formed a monophyletic group.The conservation status of B.nivea var.strigosa is assessed as“Near Threatened”(NT)according to IUCN evaluation criteria.The discovery of this new variety is not only crucial for the taxonomy of ramie,but also provides reference for the exploration and utilization of ramie.

Comparative Analysis of Energy Characteristics of Two Southwest Vortices in Sichuan Under Similar Circulation Backgrounds

Based on ERA5 reanalysis data,the present study analyzed the thermal energy development mechanism and kinetic energy conversion characteristics of two extreme rainstorm processes in relation to the shallow southwest vortex in the warm-sector during a“rain-generated vortex”process and the deep southwest vortex in a“vortex-generated rain”process.The findings were as follows:(1)During the extreme rainstorm on August 11,2020(hereinafter referred to as the“8·11”process),intense surface heating and a high-energy unstable environment were observed.The mesoscale convergence system triggered convection to produce heavy rainfall,and the release of latent condensation heat generated by the rainfall promoted the formation of a southwest vortex.The significant increase(decrease)in atmospheric diabatic heating and kinetic energy preceded the increase(decrease)in vorticity.By contrast,the extreme rainstorm on August 16,2020(hereinafter referred to as the“8·16”process)involved the generation of southwest vortex in a low-energy and highhumidity environment.The dynamic uplift of the southwest vortex triggered rainfall,and the release of condensation latent heat from rainfall further strengthened the development of the southwest vortex.The significant increase(decrease)in atmospheric diabatic heating and kinetic energy exhibited a delayed progression compared to the increase(decrease)in vorticity.(2)The heating effect around the southwest vortex region was non-uniform,and the heating intensity varied in different stages.In the“8·11”process,the heating effect was the strongest in the initial stage,but weakened during the vortex's development.On the contrary,the heating effect was initially weak in the“8·16”process,and intensified during the development stage.(3)The available potential energy of the“8·11”process significantly increased in kinetic energy converted from rotational and divergent winds through baroclinic action,and the divergent wind energy continued to convert into rotational wind energy.By contrast,the“8·16”process involved the conversion of rotational wind energy into divergent wind energy,which in turn converted kinetic energy back into available potential energy,thereby impeding the further development and maintenance of the southwest vortex.

The Spatial-Temporal Characteristics of Meteorological Disasters in the Southwest Region of Zhejiang Province during 1953-2022

Meteorological disasters are some of the most serious and costly natural disasters, which have larger effects on economic and social activity. Liuchun Lake is an ecotourism area in the southwest region of Zhejiang province, where also has experienced meteorological disasters including rainstorm and cold wave. Understanding the temporal-spatial characteristics of meteorological disasters is important for the local tourism and economic development. Based on the daily temperature and precipitation from 18 meteorological stations in the southwest of Zhejiang province during 1953-2022 and some statistical approaches, the temporal and spatial characteristics of meteorological disasters (Freezing, Rainstorm, Cold wave) are analyzed. The results indicate that 1) Rainstorm occurred frequently around the Liuchun lake, the frequency was about 8 times/a, it can also reach about 3 times/a in the other region. Freezing and cold wave (including strong cold wave and extremely cold wave) had the same spatial distribution as rainstorm, however, except for Liuchun lake, they occurred less than one time in the other regions;2) The trend of rainstorm had larger spatial difference, it increased in all the study area, but it increased more significantly around the study area than around Liuchun lake. Freezing was on the downtrend in the whole region, with 93.3% of the stations passed the 95% significant level. Cold wave also showed a declined trend, but it was insignificantly at most of the stations, only 33% of the stations passed the 90% significant level. Compared with cold wave, strong cold wave and extremely strong cold wave had weaker decline in all the regions. In general, from 1953 to 2022 rainstorm showed an increasing trend, it was the main meteorological disaster in the study area, cold wave displayed a decreasing trend, but it still occurred about 2 - 3 times/a in most regions.

The Impact of Arid Climate Change on Agriculture of Dry Valley in Southwest China and Its Adaptive Countermeasures

The eco-environmental vulnerability and underdevelopment of the agriculture in Southwest China would strengthen its disadvantage conditions further on the condition of arid climate change.It is necessary to deal with the relations between resource utilization and eco-environment finely and ascertain the adaptive principles on the dry valley agriculture to the arid climate change in order to change the extensive utilization of the special agricultural resources.The paper gave some adaptive countermeasures that develop modern rangeland husbandry,strengthening the special agriculture and agricultural industrialization,emphasis on the ecological agriculture development,constructing the extension system of water-saving modern agriculture,encouraging the service industry related to ＂agriculture,peasants and the countryside＂,constructing water utilization facilities,and exploiting the renewable energies.

Drought in Southwest China: A Review

The clustering of severe and sustained droughts in Southwest China(SWC)during the last decade has resulted in tremendous losses,including crop failure,a lack of drinking water,ecosystem destruction,health problems,and even deaths.Various attempts have been made to explore the variability and causes of drought in SWC.Here,the authors summarize and integrate this accumulated but fragmented knowledge.On the whole,general agreement has been reached on the evolution of drought in SWC,which has become more frequent and intense during the past 50 years and is projected to continue throughout the 21st century.However,it is unclear and even disputable as to what and how sea surface temperatures and circulation oscillation patterns affect the drought condition.Meanwhile,the presence of strong nonlinearity places considerable challenges in both understanding and predicting drought in SWC.Therefore,much remains to be learned concerning the mechanisms responsible for drought disasters in SWC and accurate forecast practice.In addition to pursuing research on factors and processes involved in drought formation,above all,there is an urgent need to develop appropriate strategies and plans for mitigating the threats of drought.

Observational Facts Regarding the Joint Activities of the Southwest Vortex and Plateau Vortex after Its Departure from the Tibetan Plateau

Using atmospheric observational data from 1998 to 2013,station rainfall data,TRMM（Tropical Rainfall Measuring Mission） data,as well as annual statistics for the plateau vortex and shear line,the joint activity features of sustained departure plateau vortexes（SDPVs） and southwest vortexes（SWVs） are analyzed.Some new and useful observational facts and understanding are obtained about the joint activities of the two types of vortex.The results show that：（1） The joint active period of the two vortexes is from May to August,and mostly in June and July.（2） The SDPVs of the partnership mainly originate near Zaduo,while the SWVs come from Jiulong.（3） Most of the two vortexes move in almost the same direction,moving eastward together with the low trough.The SDPVs mainly act in the area to the north of the Yangtze River,while the SWVs are situated across the Yangtze River valley.（4） The joint activity of the two vortexes often produces sustained regional heavy rainfall to the south of the Yellow River,influencing wide areas of China,and even as far as the Korean Peninsula,Japan and Vietnam.（5） Most of the two vortexes are baroclinic or cold vortexes,and they both become strengthened in terms of their joint activity.（6） When the two vortexes move over the sea,their central pressure descends and their rainfall increases,especially for SWVs.（7） The two vortexes might spin over the same area simultaneously when there are tropical cyclones in the eastern and southern seas of China,or move southward together if a tropical cyclone appears near Hainan Island.

Assessment of Future Drought in Southwest China Based on CMIP5 Multimodel Projections

In the last decade, a series of severe and extensive droughts have swept across Southwest China, resulting in tremendous economic losses, deaths, and disruption to society. Consequently, this study is motivated by the paramount importance of as- sessing future changes in drought in Southwest China. Precipitation is likely to decrease over most parts of Southwest China around the beginning of the century, followed by widespread precipitation increases; the increase in potential evapotran- spiration （PET）, due to the joint effects of increased temperature and surface net radiation and decreased relative humidity, will overwhelm the whole region throughout the entire 21st century. In comparative terms, the enhancement of PET will outweigh that of precipitation, particularly under Representative Concentration Pathway （RCP） 8.5, resulting in intensified drought. Generally, the drying tendency will be in the southeast portion, whereas the mountainous region in the northwest will become increasingly wetter owing to abundant precipitation increases. Droughts classified as moderate/severe according to historical standards will become the norm in the 2080s under RCP4.5/RCP8.5. Future drought changes will manifest different characteristics depending on the time scale： the magnitude of change at a time scale of 48 months is nearly twice as great as that at 3 months. Furthermore, we will see that not only will incidences of severe and extreme drought increase dramatically in the future, but extremely wet events will also become more probable.

Geochemistry and SHRIMP Zircon U-Pb Age of Post-Collisional Granites in the Southwest Tianshan Orogenic Belt of China:Examples from the Heiyingshan and Laohutai Plutons

The Heiyingshan granite and the Laohutai granite plutons exposed in the Southwest Tianshan resemble A-type granites geochemically. Analysis shows that the both are ferron calc-alkalic peraluminous or ferron alkali-calcic peraluminous with a relatively high concentration of SiO2 （〉70%）, high alkali contents （Na20 ＋ K20 = 7.14%-8.56%; K20〉N20; A/CNK = 0.99-1.20）, and pronounced negative anomales in Eu, Ba, St, P and Ti. A SHRIMP zircon U-Pb age of 285±4 Ma was obtained for the Heiyingshan hornblende biotite granite intrusion. The geochemical and age dating data reported in this paper indicate that these granites were formed during the post-collisional crustal extension of the Southwest Tianshan orogenic belt, in agreement with the published data for the granites in the South Tianshan.

Late Silurian to Early Devonian Palynomorphs from Qujing,Yunnan,Southwest China

Well-preserved and diversified spores,cryptospores,and acritarchs have been recorded from a relatively continuous sequence that encompasses the Silurian-Devonian boundary in Qujing, Yunnan,southwest China.Four spore assemblage zones from Late Silurian to Early Devonian in age are proposed based on the first appearance datum（FAD）of characteristic spore species.In ascending stratigraphic order,they are Ambitisporites dilutus-Apiculiretusispora synorea（DS;Late Ludfordian to Early Pridoli）,Synorisporites verrucatus-Apiculiretusispora plicata（VP;Pridoli）,Apiculiretusispora minuta-Leiotriletes ornatus（MO;Lochkovian）,and Verrucosisporites polygonalis-Dibolisporites wetteldorfensis（PW;Pragian）.The acritarch assemblage from the upper part of the Yulongsi Formation,the Xiaxishancun Formation,and the lower-middle parts of the Xitun Formation indicates an age of Late Silurian.Based on palynological evidence,the upper part of the Yulongsi Formation is considered Late Ludfordian to Early Pridoli in age;the Xiaxishancun Formation is believed to be Pridoli in age;the Xitun Formation is considered Late Pridoli to Early Lochkovian in age;the Guijiatun Formation is considered Lochkovian in age;and the Xujiachong Formation is Late Lochkovian to Pragian in age.The Silurian-Devonian boundary is recognized between the VP and the MO spore biozones,and occurs within the middle part of the Xitun Formation.

The Energy Budget of a Southwest Vortex With Heavy Rainfall over South China

Energy budgets were analyzed to study the development of an eastward propagating southwest vortex (SWV) associated with heavy rainfall over southern China(11-13 June 2008).The results show that kinetic energy(KE) generation and advection were the most important KE sources,while friction and sub-grid processes were the main KE sinks.There was downward conversion from divergent to rotational wind KE consistent with the downward stretching of SWVs.The Coriolis force was important for the formation and maintenance of the SWV.Convergence was also an important factor for maintenance,as was vertical motion during the mature stage of the SWV and the formation stage of a newly formed vortex(vortex B).The conversion from available potential energy(APE) to KE of divergent wind can lead to strong convection.Vertical motion influenced APE by dynamical and thermal processes which had opposite effects. The variation of APE was related to the heavy rainfall and convection;in this case,vertical motion with direct thermal circulation was the most important way in which APE was released,while latent heat release and vertical temperature advection were important for APE generation.

Biostratigraphy of Triassic Marine Reptiles in Southwest Guizhou and Its Adjacent Area

This paper briefly reviews the Triassic marine reptile fossils in Guizhou Province, especially the fossils that have been recently found in the Guanling area. Based on three sections at Guanling and Xingyi, Guizhou Province and Luoping, Yunnan Province, four horizons with vertebrate fossils are recognized in the Middle and Upper Triassic of this area; They are from bottom to top: Member I and Member II of the Guanling Formation, and the Zhuganpo Member and the Wayao Member of the Falang Formation.