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Osteosarcoma is a bone tumor that often affects children, adolescents and young people. Non-coding RNA activated by DNA damage (NORAD) can promote the proliferation of cancer cells in multiple tumors. Thus, the current study set out to explore the role of NORAD derived from extracellular vesicles (EVs) of bone mesenchymal stem cells (BMSCs) in osteosarcoma. First, NORAD was highly expressed in osteosarcoma cells and tissues, which might be associated with the progression and metastasis of osteosarcoma. We isolated EVs from the characterized BMSCs, and found that NORAD was transferred from BMSCs to osteosarcoma cells via EVs in the co-culture system. Consequently, NORAD delivered by BMSC-derived EVs promoted the proliferation and invasion of osteosarcoma cells. Subsequently, bioinformatics analyses suggested potential binding relationship between NORAD and microRNA-30c-5p (miR-30c-5p) as well as between miR-30c-5p and Krueppel-like factor 10 (KLF10), and the results of which were further verified by dual luciferase reporter gene assay, RNA immunoprecipitation, and RNA pull-down assay. Mechanistically, NORAD acted as a sponge of miR-30c-5p and up-regulated the expression of KLF10 where miR-30-c-5p mimic declined the effect induced by NORAD on cancer cells. The osteosarcoma cells were injected into mice to develop tumor growth and metastasis models. In these two models, injection of BMSC-EVs elevated NORAD expression and KLF10 but reduced miR-30c-5p expression, whereby suppressing tumor growth and lung metastasis. To conclude, BMSC-EVs deliver NORAD to osteosarcoma cells to regulate the miR-30c-5p/KLF10 axis, thereby accelerating the progression and metastasis of osteosarcoma.

Based on correlation between geochemical characteristics of Sinian and Cambrian source rocks and discovered gas reservoirs, paleoand the analysis on geological conditions of reservoir formation, the sources of natural gas in the Sinian of Sichuan Basin have been discussed to sort out the contribution of Sinian source rocks to the gas reservoirs and effectiveness of Sinian primary gas-bearing system. Through the analysis of natural gas composition, carbon and hydrogen isotopes and effectiveness of Sinian accumulation assemblages, it is concluded that: (1) The natural gas derived from the Sinian source rock is characterized by low ethane content, heavy ethane carbon isotope and light methane hydrogen isotope, and obviously different from the gas generated by the Cambrian source rock. (2) The gas reservoirs discovered in Sinian Dengying Formation are sourced by Sinian and Cambrian source rocks, and the Sinian source rock contributes different proportions to the gas in the 4th member and the 2nd member of the Dengying Formation, specifically, 39% and 55% to the 4th member in marginal zone and intra-platform, 54% and 68% to the 2th member in the marginal zone and intra-platform respectively. (3) The effectiveness of the Sinian primary gas-bearing system depends on the gas generating effectiveness of the source kitchen, reservoir and combination of gas accumulation elements. For high-over mature marine source rocks at the Ro of less than 3.5%, besides gas generated from the thermal cracking of liquid hydrocarbon, the kerogen still has some gas generation potential by thermal degradation. In addition, the Sinian microbial dolomite still preserves relatively good-quality reservoirs despite large burial depths, which match well with other basic conditions for gas accumulation in central Sichuan paleo-uplift, increasing the possibility of Sinian primary gas-bearing system. The research results confirm that the Sinian primary gas-bearing system is likely to form large-scale accumulation.

Because of the differences of hydrocarbon accumulation between in-source and out-of-source oil pools, the demand for source kitchen is different. Based on the establishment of source-to-reservoir correlation in the known conventional accumulations, and the characteristics of shale oil source kitchens as well, this paper discusses the differences of source kitchens for the formation of both conventional and shale oils. The formation of conventional oil pools is a process of hydrocarbons enriching from disperse state under the action of buoyancy, which enables most of the oil pools to be formed outside the source kitchens. The source rock does not necessarily have high abundance of organic matter, but has to have high efficiency and enough amount of hydrocarbon expulsion. The TOC threshold of source rocks for conventional oil accumulations is 0.5%, with the best TOC window ranging from 1% to 3%. The oil pools formed inside the source kitchens, mainly shale oil, are the retention of oil and gas in the source rock and there is no large-scale hydrocarbon migration and enrichment process happened, which requires better quality and bigger scale of source rocks. The threshold of TOC for medium to high maturity of shale oil is 2%, with the best range falling in 3%–5%. Medium to low mature shale oil resource has a TOC threshold of 6%, and the higher the better in particular. The most favorable kerogen for both high and low-mature shale oils is oil-prone type of I–II1. Carrying out source rock quality and classification evaluation and looking for large-scale and high-quality source rock enrichment areas are a scientific issue that must be paid attention to when exploration activity changes from out-of-source regions to in-source kitchen areas. The purpose is to provide theoretical guidance for the upcoming shale oil enrichment area selection, economic discovery and objective evaluation of resource potential.

A new method for reconstructing the geological history of hydrocarbon accumulation is developed, which are constrained by U-Pb isotope age and clumped isotope (Δ47) temperature of host minerals of hydrocarbon-bearing inclusions. For constraining the time and depth of hydrocarbon accumulation by the laser in-situ U-Pb isotope age and clumped isotope temperature, there are two key steps: (1) Investigating feature, abundance and distribution patterns of liquid and gaseous hydrocarbon inclusions with optical microscopes. (2) Dating laser in-situ U-Pb isotope age and measuring clumped isotope temperature of the host minerals of hydrocarbon inclusions. These technologies have been applied for studying the stages of hydrocarbon accumulation in the Sinian Dengying gas reservoir in the paleo-uplift of the central Sichuan Basin. By dating the U-Pb isotope age and measuring the temperature of clumped isotope (Δ47) of the host minerals of hydrocarbon inclusions in dolomite, three stages of hydrocarbon accumulation were identified: (1) Late Silurian: the first stage of oil accumulation at (416±23) Ma. (2) Late Permian to Early Triassic: the second stage of oil accumulation between (248±27) Ma and (246.3±1.5) Ma. (3) Yanshan to Himalayan period: gas accumulation between (115±69) Ma and (41±10) Ma. The reconstructed hydrocarbon accumulation history of the Dengying gas reservoir in the paleo-uplift of the central Sichuan Basin is highly consistent with the tectonic-burial history, basin thermal history and hydrocarbon generation history, indicating that the new method is a reliable way for reconstructing the hydrocarbon accumulation history.

The late Cambrian extinction – Early Ordovician biodiversification represents one of the crucial lower Paleozoic biological changes. However, the mechanisms responsible for this transition remain poorly understood. Here, we reconstructed the paleoenvironmental changes based on a model that integrated the atmospheric-oceanic-biological inputs and provided the first detailed assessment of the Cambro-Ordovician biological turnover. The results show depositional environments evolved into extremely sulfidic conditions with lower nutrient inputs and more restricted water circulation from the Miaolingian to early Furongian, leading to the Steptoean Positive Carbon Isotope Excursion event. The intense volcanic activity in the early Jiangshanian appears to be responsible for the recurrent bio-calamity. Later in the mid-late Furongian (mid-Jiangshanian to Stage 10), enhanced terrestrial weathering contributed to the Earth's cooling and higher inputs of terrestrial nutrients, beneficial to the subsequent biological recovery. In the Early Ordovician and despite reduced terrestrial nutrient input, massive oceanic water upwelling alleviated sulfidic conditions and brought nutrients, laying the foundation for the Great Ordovician Biodiversification Event.

To construct a giant Sichuan gas province, it is in an urgent need of exploring new replacement areas with abundant natural gas resources and great exploration potential. In this paper, the formation conditions (e.g. source rock, reservoir and play) and the distribution laws of the deep-seated old giant marine carbonate oil/gas fields in China's Craton Basins were investigated systematically. Then, the accumulation and enrichment conditions of deep Sinian natural gas in the Sichuan Basin were analyzed. Finally, potential and favorable target zones of natural gas exploration in the Dengying Formation of Upper Sinian were evaluated. And the following research results were obtained. Firstly, the effectiveness and scale of source kitchens, reservoirs and reservoir–caprock assemblages and the proximity are the necessary conditions for the formation of deep-seated giant carbonate oil/gas fields, and paleo-uplifts, paleo-slopes and paleo-fault zones are the favorable areas of searching deep-seated giant carbonate oil/gas fields. Secondly, in the Sichuan Basin, three sets of high-quality source rocks are developed in the Neoproterozoic–Cambrian System, and their maturity of organic matter is still in the optimal window for cracking gas, so the gas generation scale is large. Thirdly, after the microbial carbonate rocks of Dengying Formation in the Sichuan Basin were reconstructed by constructive diagenesis, effective reservoirs are formed and distributed widely. Fourthly, owing to the integrated source rocks and cap rocks of Dengying Formation, the marginal platform and the intra platform have favorable conditions for proximal hydrocarbon accumulation. In conclusion, the deep Sinian in the Sichuan Basin has good conditions of hydrocarbon accumulation and it is an important replacement area of natural gas exploration. Paleo-uplifts and slopes in the central Sichuan Basin have been the favorable locations of natural gas accumulation for a long period. Large-scale exploration shall focus on four favorable areas, including the marginal platform zone in the fourth member of Dengying Formation, the marginal platform zone in the second member of Dengying Formation, the bioherm shoalbody of Dengying Formation intra platform in the paleo-uplifts and slopes of the central Sichuan Basin, and the bioherm shoalbody of Dengying Formation in the eastern Sichuan Basin.

Continental shale oil has two types, low-medium maturity and medium-high maturity, and they are different in terms of resource environment, potential, production methods and technologies, and industrial evaluation criteria. In addition, continental shale oil is different from the shale oil and tight oil in the United States. Scientific definition of connotations of these resource types is of great significance for promoting the exploration of continental shale oil from “outside source” into “inside source” and making it a strategic replacement resource in the future. The connotations of low-medium maturity and medium-high maturity continental shale oils are made clear in this study. The former refers to the liquid hydrocarbons and multiple organic matter buried in the continental organic-rich shale strata with a burial depth deeper than 300 m and a Ro value less than 1.0%. The latter refers to the liquid hydrocarbons present in organic-rich shale intervals with a burial depth that in the “liquid window” range of the Tissot model and a Ro value greater than 1.0%. The geological characteristics, resource potential and economic evaluation criteria of different types of continental shale oil are systematically summarized. According to evaluation, the recoverable resources of in-situ conversion technology for shale oil with low-medium maturity in China is about (700–900)×108 t, and the economic recoverable resources under medium oil price condition ($ 60–65/bbl) is (150–200)×108 t. Shale oil with low-medium maturity guarantees the occurrence of the continental shale oil revolution. Pilot target areas should be optimized and core technical equipment should be developed according to the key parameters such as the cumulative production scale of well groups, the production scale, the preservation conditions, and the economics of exploitation. The geological resources of medium-high maturity shale oil are about 100×108 t, and the recoverable resources can to be determined after the daily production and cumulative production of a single well reach the economic threshold. Continental shale oil and tight oil are different in lithological combinations, facies distribution, and productivity evaluation criteria. The two can be independently distinguished and coexist according to different resource types. The determination of China's continental shale oil types, resources potentials, and tight oil boundary systems can provide a reference for the upcoming shale oil exploration and development practices and help the development of China's continental shale oil. Key words: shale oil, medium-high maturity, low-medium maturity, resource potential, tight oil, boundary, shale oil revolution

The Junggar Basin is one of the major petroliferous basins with abundant oil and gas resources in onshore China. Around 2010 and thereafter, the hydrocarbon exploration for finding giant fields in the basin faced tough difficulties: in the northwestern margin area, no significant breakthrough has been made for long since seeking to “escape from the step-fault zone and extend to the slope area”; in the central part, the exploration for large lithologic-stratigraphic reservoirs stood still; since the discovery of the Kelameili gas field, no important achievement has been made in gas exploration. Under the guidance of “whole sag-oil-bearing” theory in the petroliferous basin, and based on the long-term study and thinking of the petroleum accumulation conditions and characteristics, the authors proposed several new concepts, i.e., a “thrust-induced second-order fault step” hiding under the northwestern slope area; six “hydrocarbon migrationward surfaces” favorable for hydrocarbon accumulation; promising natural gas resource. These concepts have played an important role in the discoveries of Wells Mahu1 and Yanbei1 as well as the confirmation and expansion of Permian-Triassic billion-ton-scale petroliferous areas in Mahu. The fairway of new discoveries has also appeared for natural gas exploration in Wells Fu26, Gaotan1 and Qianshao2, suggesting that the surrounding regions of the highly matured source kitchen are of high possibility to form gas accumulations. Key words: second-order fault step, hydrocarbon migrationward surface, favorable facies belt, lithologic-stratigraphic reservoir, whole sag-oil-bearing, natural gas, potential and direction, Junggar Basin

The top sandstone (S1) of the middle Triassic Karamay Formation (T2k) is one of the major pay zones in the Mahu field, Junggar Basin, northwestern China. Both spatial distribution and internal architecture of the reservoirs are important for resource evaluation and petroleum production in the field. Seismic sedimentology, an integrated study of seismic geomorphology and seismic lithology, was applied to well and three-dimensional (3-D) seismic data to analyze distribution of sedimentary facies and reservoirs. Lithologies in the study area consist of conglomerate, sandstone, and mudstone. Acoustic impedance (AI) of mudstone (6–9 × 106 kg/[s*m2]) is lower than the other two lithologies, which have similar AI values (9–14 × 106 kg/[s*m2]). Therefore, seismic amplitude can distinguish mudstone from conglomerate and sandstone, but fails to differentiate conglomerate from sandstone. Seismic geomorphology was employed to qualitatively predict distribution of sandstone and conglomerate respectively using frequency decomposition, seismic-attribute extraction, and red-green-blue (RGB) color-blending techniques. In the seismic lithologic study, principal component analysis (PCA) was utilized to transfer multiple seismic attributes into principal components. Selected principal components were then fit with cumulative reservoir thickness interpreted from porosity-log data, resulting in quantitative estimation of interwell thin (10 m or thinner) reservoir distribution. Meandering fluvial facies were recognized for the first time in the previously interpreted fan-delta facies zone. Meandering channels formed when the lake level rose in relatively humid climate during a time with few tectonic activities. The previously formed fan-delta was substituted by a later formed meandering channel, which flowed into the southwestern lake from the north. Sediment distribution was controlled by accumulation space or paleogeomorphology restored by cast method; sediment is thick in paleolow terrains and thin in paleohigh areas. Locality of reservoir rock is basically coincident with sandstone distribution. Thick reservoir rocks with high porosity (greater than 10%) are located mainly in areas with moderately thick sandstones formed in point-bar subfacies of fluvial systems and in lower-fan subfacies of the fan-delta system. Higher petroleum production in individual wells drilled in the fluvial system indicates superior physical properties there. As a result, locating point-bar subfacies is key to improving hydrocarbon exploration and development.

Demand for irrigation water has been steadily increasing in arid regions where intensification of crop production is supported by flood-irrigation. An assessment of irrigation performance, water productivity, and irrigation schedules is critical to water conservation in dry climates. In this study, we conducted a field experiment to compare soil water balance in a flood-irrigated wheat-maize rotation system during the growing season of 2015–2016. We then modeled the soil water balance and improved irrigation strategies by coupling Hydrus-1D with the CROPWAT model, and using evapotranspiration calculated from climatic data. The calibrated Hydrus-1D model was used to simulate the temporal and spatial variation of evapotranspiration and deep percolation based on measured soil water distribution of soil profiles in the unsaturated zone. Results showed that using soil hydraulic parameters from inversion modeling can simulate soil water flow in multi-layer soil during a crop growing season. Simulation results indicated that about 36.6 and 40.6% (478.6 and 680.1 mm) of total water input in 2015 and 2016, respectively, was consumed by evapotranspiration. Furthermore, simulated deep percolation amounted for approximately 32.3 and 42.9% (403.9 and 696.6 mm) of the total amount of irrigation water in 2015 and 2016, respectively. These results indicated that only a small proportion of irrigation water was used by crops for transpiration. In addition, irrigation performance indicators such as relative water supply, relative irrigation supply, depleted fraction, and overall consumed ratio values indicated poor performance of irrigation practices in the study area. Particularly, crop yields did not increase with increases in irrigation water in flood-irrigated fields during the last ten years. Results of the CROPWAT model indicated that combinations of a fixed irrigation depth and timing, of 40 mm every 10 days, and 50 mm every 10 days were reasonable for wheat and maize, respectively, given the sandy soil in the study area. The improved irrigation strategies will limit water irrigation loss to 20% without significant effects on crop yields. This study provides an alternative approach for estimating deep percolation and crop water requirements supporting management efforts in water conservation in dry climates.

Urban scenes refer to city blocks which are basic units of megacities, they play an important role in citizens’ welfare and city management. Remote sensing imagery with largescale coverage and accurate target descriptions, has been regarded as an ideal solution for monitoring the urban environment. However, due to the heterogeneity of remote sensing images, it is difficult to access their geographical content at the object level, let alone understanding urban scenes at the block level. Recently, deep learning-based strategies have been applied to interpret urban scenes with remarkable accuracies. However, the deep neural networks require a substantial number of training samples which are hard to satisfy, especially for high-resolution images. Meanwhile, the crowed-sourced Open Street Map (OSM) data provides rich annotation information about the urban targets but may encounter the problem of insufficient sampling (limited by the places where people can go). As a result, the combination of OSM and remote sensing images for efficient urban scene recognition is urgently needed. In this paper, we present a novel strategy to transfer existing OSM data to high-resolution images for semantic element determination and urban scene understanding. To be specific, the object-based convolutional neural network (OCNN) can be utilized for geographical object detection by feeding it rich semantic elements derived from OSM data. Then, geographical objects are further delineated into their functional labels by integrating points of interest (POIs), which contain rich semantic terms, such as commercial or educational labels. Lastly, the categories of urban scenes are easily acquired from the semantic objects inside. Experimental results indicate that the proposed method has an ability to classify complex urban scenes. The classification accuracies of the Beijing dataset are as high as 91% at the object-level and 88% at the scene level. Additionally, we are probably the first to investigate the object level semantic mapping by incorporating high-resolution images and OSM data of urban areas. Consequently, the method presented is effective in delineating urban scenes that could further boost urban environment monitoring and planning with high-resolution images.

Many studies have uncovered the essential role of ZBTB7A in regulating tumourigenesis. However, its functional significance in cell responses to endoplasmic reticulum stress (ER stress) remains poorly understood. Here we report that ZBTB7A functions as an important prosurvival factor in osteosarcoma cells undergoing pharmacological ER stress-induced by tunicamycin (TM) or thapsigargin (TG). The downregulation of ZBTB7A expression by ER stress promoted cell apoptosis in vitro and in vivo. ZBTB7A expression levels were increased in osteosarcoma tissues and elevated ZBTB7A was associated with osteosarcoma metastasis. Further mechanistic studies revealed that miR-663a induced by ER stress directly bound to the 3′UTR of ZBTB7A and contributed to ER stress-induced ZBTB7A downregulation in osteosarcoma cells. Additionally, our data revealed that ZBTB7A bound to the promoter of LncRNA GAS5 and transcriptionally suppressed LncRNA GAS5 expression, leading to a decline in ER stress-induced cell apoptosis. Collectively, our findings reveal the prosurvival role of ZBTB7A in osteosarcoma adaptation to ER stress and suggest that the miR-663a-ZBTB7A-LncRNAGAS5 pathway is essential for the survival of human osteosarcoma cells under ER stress.

Salt dissolved in soil water is transported upward to the soil surface through capillary rise from shallow groundwater, leading to salt accumulation near the surface and salinization of wetlands in arid regions. However, it is not clear how the mechanism and feedback for evapotranspiration induces salt accumulation and precipitation. Here, we developed a model to simulate the transport of water, solutes, and heat, and measured the meteorological, hydrological, and hydraulic parameters of soil using field experiments to calibrate the model for riparian and saltmarsh wetlands in northwestern China. The results showed that the annual atmospheric precipitation averaged 125.3 ± 10.2 mm in two types of wetlands, the evapotranspiration, depth to the groundwater and soil salinity averaged 587.7 mm yr−1, 85.4 ± 5.4 cm and 29.80 g kg−1 in the riparian wetland, while 637.2 mmyr−1, 129.7 ± 15.1 cm and 63.64 g kg−1 in the saltmarsh wetland, respectively. We found that the flux of liquid water, flux of water vapor, salinity, and efflorescence had maximum values of 1.23 mm day−1, 0.22 mm day−1, 104.16 g kg−1, and 2.10 cm in the riparian wetland, respectively, versus 1.28 mm day−1, 0.32 mm day−1, 202.02 g kg−1, and 3.70 cm in the saltmarsh wetland. Our simulations show that the salinity increases significantly with increasing evapotranspiration, soil temperature, saturated water content, and groundwater depth in the saltmarsh wetland, but that the effects of saturated water content and groundwater depth were small in the riparian wetland. As a result of these factors, the efflorescence pattern exhibited characteristic seasonal and inter-annual variability in which complex interactions among atmospheric precipitation, evapotranspiration, groundwater, and river water provided the long-term driving forces for water flow and salt transport. We found that the increasing efflorescence disrupted evaporation more than subflorescence, which reduced the soil porosity and possibly affected water vapor transport.

Selective phosphatidylinositol 3 kinase (PI3K) inhibitors are being actively tested in clinical trials for ERα-positive (ER+) breast cancer due to the presence of activating PIK3CA mutations. However, recent studies have revealed that increased ERα transcriptional activity limits the efficacy of PI3K inhibitor monotherapy for ER + breast cancers. Herein, we report the identification of BTF3 as an oncogenic transcription factor that regulates ERα expression in luminal breast cancers. Our TCGA analysis reveals high expression levels of BTF3 in luminal/ER + breast cancer and cell line models harboring ERα overexpression. Concordantly, BTF3 expression is highly and strongly associated with ESR1 expression in multiple breast cancer cohorts. We further show that BTF3 promotes the proliferation, survival and migration of ER + breast cancer cells by modulating ESR1 expression and ERα-dependent transcription. Moreover, BTF3 knockdown sensitizes ER + breast cancer cells to the PI3Kα inhibitor BYL-719 in both in vitro and in vivo models. Together, our findings highlight a novel role of BTF3 in modulation of ERα-dependent transcriptional activity and its potential as a predictive marker for the response to PI3K-targeted therapy in ER + breast cancer.

The dynamics of the alpine forest boundary and the mechanisms behind have long been the ecological research hotspots. Growing season temperature (Tgs) decreases along with altitude gradients limiting alpine treeline has become the widely accepted mechanism among various theories. However, the physiological process amid Tgs limitation of the alpine treeline is still not well understood. Here, we measured leaf hydraulic conductance (Kl), stem hydraulic conductance (Ks), leaf and stem anatomic structures, and leaf saturated photosynthetic rate (Asat) of 11 tree and shrub species naturally distributed along the altitude gradients towards the typical alpine treeline in the north face of Qilian Mountains. We found, irrespective of interspecies or intraspecies, Kl and Ks both significantly decreased along the altitude gradients, and the species distributed in the high altitude with rather low Kl and Ks. The decrease of leaf midvein and stem xylem vessel diameter were the anatomical cause of the decreases of Kl and Ks. Further analysis proved that the decreased Tgs, not growing season precipitation (Pgs), was closely coordinated with the decrease of Kl and Ks along altitude gradients. The path analysis showed that the decreased Tgs, Kl, and Ks along the altitude gradients negatively influenced Asat, and thereby limits the species survival in high altitudes. The findings proposed the physiological constraints of the alpine forest treeline and provided the physiological insights for alpine forest management and conservation.

To find out the origin of dolomite, the precipitation of primary dolomite, and the formation of pores in dolomite, petrologic and geochemical characteristics of typical samples from Sichuan and Tarim Basin were analyzed based on the previous understandings, and three aspects of results were achieved. (1) A classification of dolomite origins based on petrologic features, forming environment, and time sequence was proposed, which shows clear boundaries of diagenetic and characteristic realms and evolved clues between different types of dolomite. (2) Petrographic and geochemical identification marks for different types of dolomite were presented, revealing that the orderly geochemical variation of different types of dolomite is the response to the change of forming environment of dolomite during continuous time sequence. (3) The contribution of dolomitization to the formation of porosity was re-evaluated, revealing that the porosity in dolomite was mostly attributed to the primary pores and supergene dissolution and burial dissolution, and early dolomitization was conducive to the preservation of primary pores. These understandings are of great theoretical significance for identifying the origins and types of dolomite, and can guide the prediction of dolomite reservoirs. Key words: dolomite genetic types, dolomite distinguished characteristics, dolomite porosity origin, protodolomite, primary porosity

Changes in spatial patterns of vegetation and their underlying hydrological mechanisms has significant implications for landscape ecological researches. However, empirical studies which test the relationships between vegetation spatial pattern and hydrology are scarce. Based on an in situ investigation and on geostatistical analysis, we described spatio-temporal changes in population characteristics in two shrub populations in the transition zone between oasis and desert in the Heihe River Basin, northwestern China. Our results showed that the density and cover of two dominant species were significantly greater in 2016 than in 2002. Total species richness also increased with time. N. sphaerocarpa population was distributed in small strips in 2002 and in big strips in 2016. R. soongorica population exhibited uniform distribution in 2002, and big-strip distribution pattern in 2016. The results of a semi-variogram analysis showed that the nugget/sill ratio of the two populations was 0.077 to 0.116 in 2002, and 0.066 to 0.144 in 2016. This indicated that the random variance of spatial heterogeneity occupied 7.7–11.6% of total spatial heterogeneity in 2002, and 6.6–14.4% in 2016. In 2002, the range values (A0), respectively for density and cover, were 33.09 and 14.7 m for N. sphaerocarpa, and 24.9 and 25.2 m for R. sphaerocarpa. In 2016, these values increased to 37.2 and 30.3 m for N. sphaerocarpa, and 57.3 and 75 m R. sphaerocarpa. This indicated that the scale of spatial heterogeneity for density and cover of the two dominant species increased from 2002 to 2016. Correlation analysis showed that summer precipitation and soil water content significantly related to total species richness. We concluded that summer precipitation was a key factor which affected population characteristics and spatial patterns. The mechanism driving this was a rise in summer precipitation leading to an increase in soil water content and, eventually, to a change in the spatial patterns of plants.

In irrigation-maintained desert agroecosystems in northwestern China, cereal crop production occurs mainly as maize (Zea mays L.) monoculture (MM), along with wheat (Triticum aestivum L.) monoculture (WM) and maize/wheat intercropping (MWI). However, our understanding of the role of different cropping systems in regulating the abundance and diversity of ground- and soil-dwelling insect herbivores (pests) and arthropod predators (natural enemies of pests), and thus cascading effects on biological pest control services is still poor. To address this important issue, we measured ground- and soil-dwelling insect pests and associated arthropod natural enemies in fields of MM, WM, and MWI using pitfall traps and hand-sorting in spring and summer at six sites in a desert agroecosystem in northwestern China. Each site contained three cropping systems with cultivation for at least five years. We also calculated the abundance- and richness-based ratios of ground- and soil-dwelling arthropod predators to insect herbivores (P: H ratios) as indices for assessing pest biocontrol services. For ground-dwelling communities, we found that MM harbored more abundant and diverse insect herbivores and insect predators than the other systems, whereas MWI harbored more abundant and diverse non-insect predators and had higher P: H ratios compared with the other systems across seasons. For soil-dwelling communities, we found that MM harbored more abundant and diverse insect herbivores than MWI in spring, whereas WM harbored less abundant and diverse insect herbivores than the other systems in summer. However, MWI harbored more abundant and diverse insect predators than the other systems, whereas WM harbored less abundant and diverse non-insect predators than the other systems in either season. Moreover, MM harbored more abundant and diverse non-insect predators than MWI in summer. The P: H ratios were higher in MWI than in MM and WM in spring, but did not differ across cropping systems in summer. Our results demonstrate that the magnitude and direction of the effects of cropping systems are highly season specific and vary across groups of ground- and soil-dwelling herbivores and predators. Furthermore, intercropping delivers greater pest biocontrol services than monoculture systems. These findings provide key insights towards developing more effective intercropping systems for pest suppression.

This study applied seismic-sedimentological workflow to deeply buried marine carbonate sequences in western China. The workflow aimed at integrating core, wire line log and 3D seismic data to investigate the paleogeomorphology qualitatively and reservoir thickness quantitatively in the carbonate systems. In Gaoshiti-Moxi area of Sichuan Basin, the Longwangmiao Formation was formed in sedimentary environment of carbonate platform facies. Lithofacies vary from dolomitized grainstone to mudstone, which formed shoal, lagoon, and deep shelf sub-facies. The high-porosity (porosity > 4%) reservoir rocks are related to shoal sub-facies. Seismic geomorphology was employed to restore paleostructure of Longwangmiao Formation in the study area by methods of cast and isopach, which were calibrated by well data. It was found that the paleogeomorphology and depositional facies were largely controlled by a syndepositional, en echelon fault system. Following the strategy of seismic lithology, quantitative distribution of reservoir rocks and sedimentary facies was assessed by applying principle component analysis on amplitude attributes generated from multiple frequency panels. Seismic prediction of diagenetic facies (selective dissolution) was achieved by interpreting similarity variance, a seismic geometric attribute. In summary, the procedure, combining seismic geomorphology and seismic lithology, is effective and can be used as a reference for seismic-sedimentological study in other carbonate basins in China and elsewhere. Key words: seismic sedimentology, seismic geomorphology, seismic lithology, seismic diagenetic facies, carbonates, carbonate platform, Sichuan Basin, Gaoshiti-Moxi area, Cambrian Longwangmiao Formation

A severe water shortage in arid and semiarid regions in China has triggered regulations limiting the use of irrigation water in desert-oasis agricultural systems. To determine the actual water demand of agricultural systems and to develop standards for a rational use of water resources, maize evapotranspiration rates was simulated using meta-analysis of published data, determined land-use and soil properties in Zhangye oasis area and then estimated water consumption with MODIS for arid northwestern China for the 2014 growing season. Farmland in Zhangye oasis totaled 2189.88 km2 and accounted for 25.41% of the total oasis area; crop-protecting forestland totaled 8.56 km2 and accounted for 0.10% of the total oasis area, grassland and unutilized land accounted for 1.85%, 71.48% of the total oasis area, respectively. Soil moisture capacity at saturation ranged from 21.0 to 33.0% and at field capacity from 21.0 to 31.5%. Soil bulk density ranged from 1.36 to 1.58 g cm−3. Using meta-analysis, the simulated maize evapotranspiration rate was 655.91± 20.53 mm. During 2014 growing season, minimum, optimum and maximum water consumption used for agricultural yields and oasis stability was 1.14×109 m3, 1.46×109 m3 and 1.75×109 m3, respectively. In future research, increased big picture and high frequency data will allow operational monitoring of water use and requirements and irrigation at a regional scale.

High-quality three-dimensional (3D) seismic data acquired in the central Sichuan Basin, southwestern China, offer an opportunity to map complex lithologies in a mixed siliciclastic–carbonate–evaporite system in the Lower Triassic Jialingjiang (T1j) Formation. The formation consists of siliciclastics, limestone, dolostone, anhydrite, and salt. The lithologies consist several source-reservoir-cap assemblages in the area. Lithologies in the T1j Formation change rapidly in the vertical direction, forming different interbed patterns in thin layers. In the mean time, the lateral extend of each lithology is complex. This vertical and lateral distribution makes it difficult to predict lithology by single seismic attribute. Therefore, principle component analysis (PCA) was applied to tens of seismic attributes to extract useful information. The first three components contain most (83.02–99.85%) of the lithology information preserved in seismic attributes, which were used to correlate with lithology content calculated by core-calibrated wireline logs. Correlation coefficients of the three seismic components with lithologies are significantly higher (0.37–0.79) than those of individual seismic attributes (near zero to 0.58). Different assemblies of end-member lithologies were selected from anhydrite, siliciclastics, tight dolostone, limestone, and salt to perform PCA in different sequences. Lithologic content distribution of individual end members was shown by color-blending method to map the lithology mixture. Sedimentary history in the T1j Formation was reconstructed based on lithology-mixture maps and regional geology background in the study area. Eight 4th-order sequences were interpreted in the T1j Formation. Only the second sequence was influenced by siliciclastic input, forming a complete mixed siliciclastic–carbonate–evaporite system. Open platform and/or restricted evaporative environment dominated the other seven sequences, forming a mixed carbonate–evaporite system.

The discovery of the giant Anyue gas field in Sichuan Basin gives petroleum explorers confidence to find oil and gas in Proterozoic to Cambrian. Based on the reconstruction of tectonic setting and the analysis of major geological events in Mesoproterozoic-Neoproterozoic, the petroleum geological conditions of Proterozoic to Cambrian are discussed in this paper from three aspects, i.e. source rocks, reservoir conditions, and the type and efficiency of play. It is found that lower organisms boomed in the interglacial epoch from Mesoproterozoic-Neoproterozoic to Eopaleozoic when the organic matters concentrated and high quality source rocks formed. Sinian-Cambrian microbial rock and grain-stone banks overlapped with multiple-period constructive digenesis may form large-scale reservoir rocks. However, because of the anoxic event and weak weathering effect in Eopaleozoic-Mesoproterozoic, the reservoirs are generally poor in quality, and only the reservoirs that suffered weathering and leaching may have the opportunity to form dissolution-reconstructed reservoirs. There are large rifts formed during Mesoproterozoic-Neoproterozoic in Huabei Craton, Yangtze Craton, and Tarim Craton in China, and definitely source rocks in the rifts, while whether there are favorite source-reservoir plays depends on circumstance. The existence of Sinian-Cambrian effective play has been proved in Upper Yangtze area. The effectiveness of source-reservoir plays in Huabei area depends on two factors: (1) the effectiveness of secondary play formed by Proterozoic source rock and Paleozoic, Mesozoic, Cenozoic reservoir rocks; (2) the matching between reservoirs formed by reconstruction from Mesoproterozoic- Neoproterozoic to Eopaleozoic and the inner hydrocarbon kitchens with late hydrocarbon generation. As for Tarim Basin, the time of Proterozoic and the original basin should be analyzed before the evaluation of the effective play. To sum up, Proterozoic to Cambrian in the three craton basins in China is a potential exploration formation, which deserves further investigation and research. Key words: Proterozoic, Cambrian, tectonic setting, major geological events, interglacial epoch, source rock, microbial rock, intracratonic rift, play

Non-photosynthetic vegetation (NPV) is a vital component of terrestrial ecosystems and an important indicator of grassland degradation, therefore, it is of great significance to realize its accurate evaluation. Here, we analyzed spectral characteristics of NPV of different biomass types in undisturbed vegetation (herb, subshrub and shrub), and established relationship models among dead fuel index (DFI), cellulose absorption index (CAI) and fractional cover of NPV (fNPV) based on ground hyperspectral data; then, fNPV of four grassland types were evaluated based on the models. Our results showed that: (1) NPV reflectance exhibited similar change trends for herb, subshrub, shrub, and a mixed type, although there were significant differences among values, (2) DFI and CAI, CAI and fNPV, DFI and fNPV were significantly positively correlated (p

A growing body of literature emphasizes important roles of microbial community in driving a variety of soil processes including soil respiration (Rs). However, empirical evidence for microbial regulation of Rs is still lacking in field observations. Here, we used an in situ approach to explore microbial mechanisms for the variability in Rs across elevational gradients in an alpine forest of northwestern China. Our results revealed significant differences in abundance, diversity, and composition of both bacterial and fungal community, and the variability in microbial communities was mainly explained by climatic (mean annual precipitation) and soil (C:N ratios, available phosphorus, and nitrate nitrogen) variables. Elevation also had a significant effect on Rs, and the inclusion of microbial community composition rather than microbial abundance or diversity greatly improved the prediction of Rs dynamics along elevational gradients. Other soil properties such as C:N ratios and pH were also significantly correlated to Rs, however, they were not able to account for the variability in Rs explained by microbial community composition. Our study further identified Alphaproteobacteria and Acidobacteria as the major microbial taxa driving changes in Rs along elevational gradients, with important implications for the use of these taxa to predict soil C feedbacks under climate change scenarios in alpine forest ecosystems. Overall, our findings provided important empirical evidence for microbial regulation of Rs in field observations.

Dewfall may be a critical source of moisture in desert environments and may determine sustainability of sand-stabilizing planted vegetation. However, little is known about factors responsible for dew formation, the relative importance of dew as a source of water, and its variability in plantations. During June and October of 2013, the dew amounts and duration were estimated by using the Bowen ratio energy budget technique (BREB), and the dew variability on sand dunes planted with Haloxylon ammodendron 5, 20, and 40 years before were measured by microlysimeter. We quantified dew formation characteristics in a sand-stabilizing H. ammodendron plantation at the edge of a desert oasis, northwestern China. The results indicated that the average daily amount of dew in the H. ammodendron plantations during the observation period based on BREB was 0.13 mm, and the dew duration lasted from 1 to 9.5 h. Dew occurred on 77% of growing season days, the number of days with dew amounts of >0.03 mm comprised 95% of the total dewfall days, and the cumulative amount of dew for those days was 16.1 mm. Air temperature, relative humidity, the difference between air temperature and dew point, and wind speed had significant effects on dew formation. The thresholds of the dew formation were RH >50% and wind speed

Climate-induced changes in regional precipitation are projected to affect forest water yields, although the effects are expected to vary. Few studies, in fact, have examined the response of conifer forests to increases or decreases in precipitation, in arid regions. To answer the question posed above, we investigated the variability of forest canopy transpiration versus precipitation during the 2011–2013 growing seasons, and constructed a complete hydrological budget of an arid montane spruce forest by directly measuring its main component at the stand level, at long-term experimental catchments on Qilianshan Mountain, located in the upper Heihe River Basin, in the arid region of northwest China. It was found that total precipitation during the 2012 and 2013 growing seasons was 12.3% and 36.5% higher, respectively, than during the 2011 growing season, and total stand transpiration during the 2012 and 2013 growing season was 12.5% and 21.7% higher, respectively, than during the 2011 growing season. In the study period, transpiration, soil and moss evaportranspiration, canopy evaporation, and the drainage and change in soil water storage accounted for 71.1%, 19.9%, 5.3%, and 3.8% of the precipitation, respectively. Although the precipitation increased during this study period, the increase was not sufficient to increase the forest water yield. In the future, though, if the precipitation continues to increase in this forest, it may be sufficient to effect such an increase in forest water yield.

The interactive relationships between ecological and hydrological processes drive plant performance, community structure, and community succession in arid areas. Yet the nature of potential hydrologic thresholds for responses of vegetation remains poorly understood. In this paper, we report on hydrologic thresholds associated with aboveground net primary production (ANPP) of Haloxylon ammodendron (HA) and sand-fixation region (SFR) between 1987 and 2012 in the ecotone of desert and oasis in the northwest China. In particular, we focused on precipitation and soil moisture dynamics. Our results showed that 1) ANPP and soil moisture of both HA and SFR decreased from 1987 to 2005, and then reached a stable state; 2) nonlinear models provided a much better fit to the data than linear models, highlighting the presence of a discontinuity in vegetation ANPP changes along precipitation and soil moisture gradients; 3) precipitation, accumulated between preceding-year June to current-year August, of

The practical estimation of actual crop evapotranspiration ( ET a ) frequently involves calculating a reference crop evapotranspiration ( ET ref ), and then applying suitable crop coefficients ( K c ). Two standardized calculation procedures based on the Penman-Monteith equation are commonly used as ET ref estimations ( ET o for grass and ET r for alfalfa) across diverse environments. However, not much is known about the difference between ET o and ET r and their corresponding K c values for maize in the arid environment of Northwest China with maize being the dominant crop. Estimates from the two procedures were comprehensively compared at both hourly and daily time steps for 2013 and 2014 growing seasons. The sum-of-hourly ET r and ET o (summed from hourly values over 24 h periods) values were averagely lower than their corresponding daily ET r and ET o values (calculated from daily average meteorological data) by about 1% and 5% in 2013, and 2% and 7% in 2014, respectively. The ratios of ET r to ET o varied seasonally with a mean value slightly lower than the generalized value (1.35) for arid conditions, due primarily to the differences in responsiveness of both standardized PM equations to the trends and interations among input parameters. The K c curves of maize based on grass-reference ( K co ) and alfalfa-reference ( K cr ) were experimentally derived using daily ET o and ET r combined with ET a measured by eddy covariance method. Results suggest the benefit and potentially improved accuracy for ET a estimation when applying alfalfa reference equation combined with the timestep-specific K c curves under the arid conditions. These results provide an acceptable accuracy and precision for estimation of ET a of maize field use using the standardized Penman-Monteith equations, and offer the possibility of extrapolating new sets of K co and K cr to this region or other areas with similar climatic and crop management conditions.

Contextual information, revealing relationships and dependencies between image objects, is one of the most important information for the successful interpretation of very-high-resolution (VHR) remote sensing imagery. Over the last decade, geographic object-based image analysis (GEOBIA) technique has been widely used to first divide images into homogeneous parts, and then to assign semantic labels according to the properties of image segments. However, due to the complexity and heterogeneity of VHR images, segments without semantic labels (i.e., semantic-free segments) generated with low-level features often fail to represent geographic entities (such as building roofs usually be partitioned into chimney/antenna/shadow parts). As a result, it is hard to capture contextual information across geographic entities when using semantic-free segments. In contrast to low-level features, “deep” features can be used to build robust segments with accurate labels (i.e., semantic segments) in order to represent geographic entities at higher levels. Based on these semantic segments, semantic graphs can be constructed to capture contextual information in VHR images. In this paper, semantic segments were first explored with convolutional neural networks (CNN) and a conditional random field (CRF) model was then applied to model the contextual information between semantic segments. Experimental results on two challenging VHR datasets (i.e., the Vaihingen and Beijing scenes) indicate that the proposed method is an improvement over existing image classification techniques in classification performance (overall accuracy ranges from 82% to 96%).

Sustainable use of cultivated desert soils is important for agricultural productivity in desert-oasis ecosystems. However, how soil macropore characteristics may change as a result of agricultural exploitation remains unclear. The objective of this study was to quantify and compare soil properties and macropore characteristics in an old oasis field (>50 years of cultivation, OOF), young oasis field (20 years, YOF), and adjacent uncultivated sandy land (0 year, USL) in Northwest China. Three replicated soil samples were collected from each site to investigate soil properties. Meanwhile, twelve (four replicates by three sites) intact soil core columns, 15 cm in diameter and 30 cm in height, were taken to analyze soil structure. Each soil column was scanned with a helical medical X-ray computed tomography (CT) at a voxel resolution of 0.469 mm × 0.469 mm × 0.600 mm. The results indicated that soil properties and macropore features improved after cultivation. Silt and clay content and dry mean weight diameter (DMWD) of aggregates increased with cultivation time, whereas bulk density decreased. Soil organic carbon and total nitrogen were 7.3 times and 6.7 times greater in soils at the OOF site than USL site, respectively. The increase in silt and clay content and aggregates formation likely resulted from irrigation with silt-laden river water, which in turn impacted soil nutrient accumulation. Soils at the OOF and YOF sites had greater macroporosity compared with soil at USL, and macroporosity also increased with cultivation time. X-ray CT revealed that soil macroporosity was 8.7–18.9 times greater in irrigated croplands than native desert. Soil macropores were mainly distributed at soil depths of 0–200 mm at the OOF and YOF sites, while smaller and less continuous macropores were randomly distributed across soil depths at the USL site. The larger number of macropores at the cultivated sites can be attributed to greater soil organic carbon, tillage-induced soil horizons, and alternate wetting and drying processes. Few soil macropores at the USL site may be associated with wind erosion and soil fauna burrows. Conversion of native desert soils to irrigated croplands had a positive effect on soil pore development in the desert-oasis ecotone.

Groundwater strongly impacts ecosystem performance in arid regions by driving vegetation structure and species distribution. It is unknown how water use efficiency varies along a gradient of depth to groundwater (DWT). In this study, we developed a framework to estimate water use efficiency (WUE), groundwater use efficiency (GUE), and rain use efficiency (RUE), and to examine the contribution of rainfall to transpiration in groundwater-dependent ecosystems (GDEs). The method was applied to an arid region in northwest China with a gradient of groundwater depth from 0.5 to 12 m. The results indicate that the above-ground primary production, evapotranspiration, plant transpiration, WUE, and GUE decreased significantly from riparian forest, wetland, oasis edge, desert-oasis ecotone, and to sandy desert along a gradient of increasing DWT. RUE is found to be 0.26 g m−2 mm−1 at the sandy desert without groundwater contribution where 21% of rainfall is used for transpiration. Water use efficiency increases to 0.85 g m−2 mm−1 at the riparian site where groundwater is about 0.5 m depth. The fraction of rainfall consumed by plants increases with a decreasing DWT from a threshold of 6.3 m, suggesting groundwater enhances rain use efficiency in GDEs.

Critical nitrogen dilution curves (CNDC) can efficiently diagnose nitrogen (N) condition of crops. Unfortunately, no CNDC exits for mulched drip-irrigated crops. Here we determine the CNDCs of drip-irrigated maize (Zea mays L.) with and without plastic mulch and investigate effects of plastic mulch on soil NO3−-N concentration in root zone (Nsoil), maize morphology, and CNDC changes. Aboveground dry biomass (DM), crop N concentration, soil N concentration, and related morphological characteristics of maize were measured in Northwest China under five N application rates with and without plastic mulch to calculate critical N concentration (Nc) and develop CNDCs. Plastic film mulching decreased Nsoil by 16.5 % and increased DM by 25.9 %. Mulching increased DM more than root growth and resulted in a lower root to shoot ratio compared with that of no mulching. Plastic film mulching affected CNDC and grain yields by increasing DM, thus lowering root to shoot ratio. CNDCs were Nc = 3.58DM−0.36 [R2 = 0.98] for drip-irrigated maize and Nc = 4.17DM−0.35 [R2 = 0.94] for mulched drip-irrigated maize. Mulching lowered nitrogen nutrition index at silking stage and increased it at physiological maturity stage. These results indicate that CNDC can be used to correctly determine N application rates for mulched drip-irrigated maize production.