Geochemical Characteristics of Eolian Deposits in the Chengdu Plain of Sichuan Province and the Implications for Provenance

In this study Chengdu Red Earth （CRE） from the Chengdu Plain （CP）,Sichuan province,was analyzed for its elemental （major and trace elements） and isotopic （Sm-Nd） geochemistry and compared with Pleistocene loess and paleosol samples from the Chinese Loess Plateau （CLP） in Northern China.The geochemical composition of CRE is similar to north China loess,and also resembles the average UCC.This indicates that CRE,as loess deposits in Northern China,was derived from well-mixed sedimentary protoliths that have undergone numerous upper crustal recycling processes.However,obvious differences in the geochemical characteristics of CRE and the north China loess are also revealed in our results.For chemically stable elements,CRE has higher Ti,Zr,Hf and lower ΣREE,Ba contents in comparison with loess samples from the CLP.Further analysis shows that CRE has higher TiO2/Al2O3,SiO2/Al2O3,Ba/Rb and lower Ce/Yb,Eu/Yb,LaN/YbN and ΣLREE/ ΣHREE ratios.In Sm-Nd isotopic geochemistry,Sm and Nd content and the εNd（0） value in CRE are significantly higher than those in north China loess.The higher TiO2 content in CRE coincided with a high background concentration of Ti in the Sichuan Basin and the surrounding regions.The lower ΣREE and higher Sm,Nd,εNd（0） values are related to the wide distribution of basalt in the southwest Sichuan Basin.The elemental and isotopic geochemistry of CRE indicates that eolian materials in the CP predominantly come from the Sichuan Basin and the surrounding regions,which differs from loess deposits in the CLP.

Experiences and Research Perspectives on Sustainable Development of Rice-Wheat Cropping Systems in the Chengdu Plain, China

The rice and wheat cropping pattern is one of the main cropping systems in the world. A large number of research results showed that successive cropping of rice and wheat resulted in a series of problems such as hindering nutrition absorption, gradual degeneration of soil fertility, decline of soil organic matter, and increased incidence of diseases and pests. In China, especially in the Chengdu plain where rice-wheat cropping system is practiced, productivity and soil fertility was enhanced and sustained. This paper reviews the relevant data and experiences on rice-wheat cropping in the Chengdu Plain from 1977 to 2006. The principal sustainable strategies used for rice-wheat cropping systems in Chengdu Plain included： 1） creating a favorable environment and viable rotations; 2） balanced fertilization for maintenance of sustainable soil productivity; 3） improvement of crop management for higher efficiency; and 4） use the newest cultivars and cultivation techniques to upgrade the production level. Future research is also discussed in the paper as： 1） the constant topic： a highly productive and efficient rice-wheat cropping system for sustainable growth; 2） the future trend： simplified cultivation techniques for the rice-wheat cropping system; 3） the foundation： basic research for continuous innovation needed for intensive cropping. It is concluded that in the rice-wheat cropping system, a scientific and reasonable tillage/cultivation method can not only avoid the degradation of soil productivity, but also maintain sustainable growth in the long run.

Interpretation of the Spatial Form of Chengdu Plain's Traditional Towns from the Vernacular Perspective

In recent years,with the rapid development of urbanization in our country,academic circles have paid more attentions to and made fruitful achievements on the research of vernacular settlement. On this basis,this paper took Chengdu Plain's traditional town spatial morphology as the research object to interpret its spatial form through its composition elements and characteristics which are influenced by nature,history,culture and other factors. And then,it took Jiezi ancient town as an example to analyze the renewal of its spatial form so as to inherit the vernacular culture and promote the conservation of cultural heritage and sustainable development of traditional town in the course of constructing urban cities with Chinese characteristics.

Regional landscape transformation and sustainability of the rural homegarden agroforestry system in the Chengdu Plain,China

Traditional rural homegarden agroforestry system in the Chengdu Plain of China,called“Linpan”in Chinese,integrates the ecological functions of the landscape with human production activities.Studying the driving mechanisms of rural landscape changes in the Chengdu Plain is of great significance from stakeholders’perspective.Taking the Pidu Linpan Farming System(PLFS)in the suburban area of Chengdu(designated as one of China-Nationally Important Agricultural Heritage Systems in 2020)as a case,this study combined remote sensing image analysis,oral history interviews,and focus group interviews to elucidate the driving forces of landscape changes in the PLFS.The results show that tourism development,traffic accessibility,economic demand,and agricultural heritage protection measure are the main driving forces promoting the stability and maintenance of the traditional homegardens.In contrast,population ageing,land circulation,centralized residence,climate change,and living and recreational need are the forces leading to adverse changes in the traditional homegardens.In addition,these driving forces have led to the gradual abandonment of traditional agricultural activities and critical issues related to rural landscape planning and management.The current research indicates that infrastructure construction and increased traditional agricultural income are considered as the best practices of local stakeholders,promoting the development of the protected homegardens of heritage sites and tourist destinations.Finally,we put forward some suggestions to improve and maintain the traditional rural landscape:(1)establishing a benefit-sharing mechanism;(2)establishing a training system with traditional technology and culture;(3)strengthening infrastructure construction;(4)promoting the development of the agricultural industry;(5)improving the cultural quality of farmers;and(6)establishing a management system with legal effects.This research can provide a basis for the formulation of rural landscape planning and the orderly and healthy development of agricultural heritage in Chengdu Plain.

Spatial variability of soil bulk density and its controlling factors in an agricultural intensive area of Chengdu Plain,Southwest China

Soil bulk density is a basic but important physic soil property related to soil porosity,soil moisture and hydraulic conductivity,which is crucial to soil quality assessment and land use management.In this study,we evaluated the spatial variability of soil bulk density in the 0–20,20–40,40–60 and 60–100 cm layers as well as its affecting factors in Southwest China’s agricultural intensive area.Results indicated the mean value of surface soil bulk density(0–20 cm)was 1.26 g cm^(–3),significantly lower than that of subsoil(20–100 cm).No statistical difference existed among the subsoil with a mean soil bulk density of 1.54 g cm^(–3).Spatially,soil bulk density played a similar spatial pattern in soil profile,whereas obvious differences were found in details.The nugget effects for soil bulk density in the 0–20 and 20–40 cm layers were 27.22 and27.02%while 12.06 and 3.46%in the 40–60 and 60–100 cm layers,respectively,gradually decreasing in the soil profile,indicating that the spatial variability of soil bulk density above 40 cm was affected by structural and random factors while dominated by structural factors under 40 cm.Soil organic matter was the controlling factor on the spatial variability of soil bulk density in each layer.Land use and elevation were another two dominated factor controlling the spatial variability of soil bulk density in the 0–20 and 40–60 cm layers,respectively.Soil genus was one of the dominated factors controlling the spatial variability of soil bulk below 40 cm.

Space Image of Traditional Market-Towns in Chengdu Plain from Perspective of Vernacular Culture

Traditional market-towns in Chengdu Plain are blessed with rich vernacular cultural resources. In addition to summarizing characteristics of landscape image, image of downtown street and cultural symbiosis image of the traditional market-town space, this paper, based on the discussion of the renewal design of the Ancient Luodai Town, analyzes the physical elements that constitute the space image, such as the street, interface, area, node and identifiability of landmark building, so as to explore how to create the space image of the traditional market-town with distinctive vernacular cultural characteristics in the construction of the vernacular human settlements.

Analysis of Geological Background of Seismic Activity in the Chengdu Plain from Data of Seismic Prospecting for Oil

Summarizing the existing data of seismological and geological investigations and of strong and intermediate-strong earthquakes in the Sichuan basin and its adjacent areas accumulated by the seismological and petroleum organizations in Sichuan and of the results of seismic prospecting and detailed exploration in Chengdu depression during the last 20 years permitted us to study the types and distribution of hidden structures in Chengdu depression and its adjacent areas, in particular, to identify in detail the “hidden faults" in the Chenngdu-Deyang area on the one hand; The obtained data indicate that the NE-trending Xinjin fault runs northward and dies out in the south of Penzhen town of Shuangliu County. Meanwhile, we studied genetic relations of seismic activity to active faults and their corresponding movement characteristics on the other hand. Moreover, the surface faults and deep-seated faults are clearly defined and outlined, and 5 types of seismogenic faults suggested. The knowledge thus obtained enables us to delimit the focal zones for potential strong earthquakes in Chengdu depression. The study suggests that a zone of 40 km wide and more than 100 km long on sides along the Chengdu-Deyang line has a stable seismogeological background and good engineering-seismological conditions.

Magnetostratigraphic and paleoclimatic studies on the Red Earth Formation from the Chengdu Plain in Sichuan Province,China

Two red earth sections from the Chengdu Plain in Sichuan Province are dated using geomagnetic methods. The Brunhes/Matuyama (B/M) reversal boundary is recognized within the upper parts of the two sections,and the Jaramillo normal subzone occurs in the middle-lower parts of the vermiculated red soil (VRS),which indicate that the parent material for the VRS deposited in the middle Quaternary. Sedimentologic and geochemical studies suggest that the Chengdu Clay and part of the parent material for the VRS are of aeolian origin. Pollen analysis indicates that the Chengdu Plain was mainly covered by needle-leaved forest with a cool to cool temperate humid climate when the parent material for the VRS deposited. The relatively cool to cool temperate climatic condition in the Chengdu Plain in the middle Quaternary,which may be caused by the uplift of the Tibetan Plateau,was a response to the geo-environmental changes of global significance.

基于SBAS-InSAR的成都平原地面形变监测及影响因素分析

为研究成都平原区域地面形变现状并分析影响因素,利用差分干涉测量短基线集时序分析技术(SBAS-InSAR)监测成都平原地面形变情况,研究结果表明:成都平原区域地面形变量较小,多为点状形变,个别地区存在块状形变或线状分布;形变速率较快的地块多为建设工程扰动引起的,德阳市相对比成都市更易受到工程建设的影响;大部分人工建筑区域累计形变小于14 mm,地表形变速率大于10 mm/a图斑面积为115.83 km2,主要分布在成都市邛崃市、崇州市以及德阳市旌阳区、广汉市等地.从地下水开采和土地利用方面分析成都平原地面形变影响因素得出成都平原地下水开采与地面形变现状存在一定关系,不同土地利用类型中耕地与地表形变的契合度最高,而形变面积较大的地块主要位于建筑区域.根据现场核查,SBAS-InSAR结果与现场情况较为一致,证明了SBAS-InSAR技术在地面形变监测中具有较好适用性.本研究成果可为成都平原城市建设以及国土空间规划提供依据.

成都平原经济区城市空气质量时空变化特征

基于2016—2020年成都平原经济区城市空气质量监测数据,应用空气质量综合指数评价法、Pearson相关分析法,对成都平原经济区空气质量时空变化特征、成都市主要污染物变化特征进行了研究.结果表明:1)2016—2020年,成都平原经济区城市群中空气质量指数出现了2个高值和2个低值中心,高值中心分别位于成都市、德阳市,2个低值中心分别位于雅安市、遂宁市,即成都市和德阳市空气质量最差,雅安市和遂宁市的空气质量最优;对于不同季节,1—12月,成都平原经济区的空气质量综合指数呈U字型变化,即空气质量6—10月较好,11月—次年2月较差.2)2016—2020年,成都市PM_(2.5)质量浓度值皆超过了国家二级标准限值,并且以PM_(2.5)为首要污染物出现频率最高,而O_(3)、CO、SO_(2)年均质量浓度在研究时段内均低于国家二级标准质量浓度限值.3)2016—2020年,成都市PM_(2.5)质量浓度与能见度呈显著负相关;年尺度上,成都市PM_(2.5)质量浓度与平均气温呈低度负相关,与风速、降水量呈弱负相关;季尺度上,除气温在春、夏、冬季节与PM_(2.5)质量浓度呈弱正相关外,4个季节中PM_(2.5)质量浓度与风速、降水量皆呈弱负相关.4)影响成都市PM_(2.5)质量浓度的社会经济因子主要是汽车尾气、工业烟(粉)尘排放.PM_(2.5)与地区生产总值、工业增加值、机动车保有量呈高度负相关,与工业烟(粉)尘排放量呈高度正相关.

基于多时相Sentinel-2数据的成都平原主要农作物分类

针对成都平原落实最严格的耕地保护制度对耕地“非农化”“非粮化”快速、动态监测的需求,本文研究了基于多时相Sentinel-2数据的农作物分类方法,利用主成分分析,降低了冗余信息,提高了分类精度。以2021年成都平原崇州市的7景Sentinel-2多光谱影像为数据源,构建了时序多光谱、时序主成分波段、时序植被指数、典型时相多光谱+时序植被指数等4种分类数据集,开展基于支持向量机的主要农作物分类研究。研究表明:利用主成分分析,能有效提高主要农作物的用户精度,降低农作物分类的错分率;基于典型时相多光谱+时序植被指数的数据集取得了最高的总体精度。

西部城市群产业协同发展研究--以成渝和关中平原城市群为例

为探寻进一步推进西部城市群产业协同发展情况,并为制定差别化发展政策及策略提供依据,本研究将成渝城市群和关中平原城市群作为研究西部城市群产业协同发展的示范样本区域,通过构建复合系统协同度模型的方法,缕析二者产业协同发展现状及内在机理。研究结果表明:西部地区城市群产业协同发展尚处于低水平协同阶段,并存在宏观调控能力较差、城市群内部经济体量差距较大、中心城市辐射带动作用不足、城市群缺乏竞争力等问题,并提出打破行政壁垒、提升城市能级、培育副中心城市等宏观策略以及针对不同等级城市的优化建议,为实现区域产业协同发展、提升区域经济实力提供发展参考。

成都平原地区大直径盾构选型研究

为满足成都平原地区大直径盾构隧道建设需求,本文基于已建紫瑞隧道和锦绣隧道盾构选型经验,依托在建成渝中线铁路蜀安隧道工程,研究了大直径盾构选型问题,给出了盾构机适应性配置建议。研究结果表明:(1)土压平衡和泥水平衡均可适用于成都平原地区大直径盾构隧道修建;(2)当穿越地层以泥岩为主时建议优先选择土压平衡盾构;对于局部存在高水压或强透水地层地段,可辅以地表降水+注浆加固后采用土舱上部注浓泥浆保压掘进土压平衡模式;当泥岩和砂卵石地层长度相当时,建议优先选择泥水平衡盾构或土压-泥水双模盾构;当穿越地层以砂卵石为主时,建议优先选择泥水平衡盾构;(3)城区大直径盾构隧道对地层变形控制要求高,建议盾构机预留同步注双液浆和盾体外注克泥效等惰性浆液功能。

成都平原河流阶地的发育及其对古气候和新构造运动的指示

为了研究第四纪以来成都平原古气候变化规律和新构造运动特征,对成都平原岷江水系河流阶地序列,年代格架,不同地质时期的孢粉组合特征和T4剖面上网纹红土的地球化学特征等进行了深入研究。通过收集大量存量资料,辅以少量野外查证工作,结合地质、地貌和年代学资料,厘定了成都平原岷江水系5级河流阶地,T5至T1拔河分别为98~127 m、59~79 m、36~52 m、4~10 m、2~5 m,形成时代分别为925±92 ka、722±77 ka、462±46 ka、30.13±2.86 ka、9.0 ka,其中T5、T4、T3、T2为基座阶地,发育受构造运动和气候变化共同驱动,可作为第四纪以来成都平原东缘龙泉山背斜南段隆升的地貌标志,T1为堆积阶地,发育主要受气候变化驱动;孢粉组合特征反映第四纪以来成都平原以森林草原植被为主,气候整体具由偏暖偏湿向温干变化的趋势;阶地资料揭示第四纪以来龙泉山背斜南段经历了四次间歇性隆升,隆升高度达127 m,早更新世中期龙泉山背斜南段隆升速率为0.089~0.335 mm/a,早更新世晚期隆升速率急剧下降至0.027~0.165 mm/a,然后呈现出逐渐升高的趋势,到晚更新世—全新世隆升速率上升到0.133~0.322 mm/a;龙泉山背斜南北段存在差异隆升,北段的隆升速率和隆升幅度明显大于南段,在现代地貌上表现为龙泉山北段以低山为主,南段向低山丘陵过渡。

考古遗址所见成都平原史前洪水与治水

在系统梳理成都平原地区史前考古遗址中所见古洪水证据的基础上,对古洪水发生的规律及背景因素进行分析。现有证据表明:成都平原史前古洪水多发生在宝墩文化晚期及十二桥文化时期,且多集中在4.0 ka BP及3.0 ka BP两个时间节点前后,与长江、黄河流域古洪水记录具有同步性。一方面可能与成都平原地区的地理水文要素有关;另一方面,4.0 ka BP和3.0 ka BP前后古洪水记录增多可能与4.2 ka BP及2.8 ka BP全球性气候灾变事件有关。通过探讨古蜀先民治水思想及治水技术的发展,认为古蜀先民在与洪水作斗争的过程中治水技术和治水思想也在不断地发展和进步,古蜀文明不断发展的过程也是先民不断治水并总结经验的过程,其治水技术的进步和治水思想的提高最终成就了伟大的都江堰水利工程。

乡村振兴背景下职业院校服务川西林盘保护与建设路径研究

本文围绕乡村振兴背景下职业院校如何服务川西林盘保护与建设路径展开研究。文章首先介绍了乡村振兴的重要性,以及川西林盘的衰落萎缩的现状,当前急需面临的环境挑战、转型需要、保护需求。接着,探讨了职业院校在这一过程中的角色和优势,包括提供技术支持、人才培养、文化传承等方面的服务。文章还深入分析了职业院校如何结合本地资源和实际情况,制定具体的林盘保护策略和建设路径。最后,文章强调了实践应用与创新的重要性,提出通过多方合作和资源整合,推动川西林盘保护与建设工作的深入开展。本文对于指导职业院校参与乡村振兴战略、推动川西林盘保护具有积极意义。

“公园城市乡村表达”视角下成都平原经济区传统村落的保护与利用路径

成都平原经济区位居四川省五大经济区之首,是四川省区域发展的第一增长极,也是成渝地区双城经济圈建设的重点区域。国家赋予成都建设“践行新发展理念的公园城市示范区”的历史使命,将公园城市建设与乡村振兴战略结合,走独具特色的城乡融合发展之路。传统村落的保护与利用正是成都诠释公园城市乡村表达的创新,在此视角下重新认识传统村落资源的价值特征,探究成都平原经济区传统村落保护与利用的新目标、新思路和新方法,对成都平原经济区67个国家级传统村落开展实地调研,充分挖掘传统村落特色价值、全面梳理传统村落现状问题、深入剖析问题的成因,提出基于集中连片方法的传统村落保护与利用路径,以期为成都平原经济区传统村落的相关学术研究和政策实践提供参考与借鉴。

城市土地利用与生态文明建设协调发展研究——以成都平原经济区为例

目的:分析成都平原经济区城市土地集约利用与生态文明建设耦合协调时空演变特征,并预测发展趋势。方法:耦合度、耦合协调度、相对发展度模型与灰色预测模型。结论:(1)2009—2019年成都平原经济区城市土地集约利用水平呈上升趋势,呈“中部高两侧低”特征;(2)生态文明建设水平波动上升,呈“中间低两侧高”特征;(3)两系统耦合协调度依次经历了由濒临失调到勉强协调再到初级协调的演进过程,呈“中间高两侧低”特征;(4)2020—2024年两系统耦合协调度将一直处于初级协调阶段,区域一体化程度进一步提升。

岷江流域含石膏地层地下水水化学差异性研究

位于岷江流域的成都平原及其南部的牧马山台地区域的白垩纪地层广泛发育石膏。石膏的溶蚀可显著影响地下水质,明确该类型区域地下水水化学特征空间分布并揭示其空间差异性原因,对地下水开发利用具有重要意义。以牧马山台地中部区域天府国际生物城区域为例,通过野外实地调查、采样数据的主成分分析和聚类分析、水化学演化过程数值模拟,对地下水质的现状和水质形成原因进行了系统研究。结果表明:该区地下水在水平分布和垂向分布上都存在着显著的差异性,引起水质在空间上差异的原因具有多因性。垂向上:浅层地下水受碳酸盐溶解/沉淀作用控制,地下水类型以HCO3-Ca(Ca·Mg)型为主,矿化度多小于0.5 g/L;深层地下水受地层中石膏空间分布的影响显著。在无石膏分布区,地下水以HCO3-Ca(Ca·Mg)类型的低矿化度水(TDS<0.5 g/L)为主;有石膏分布区,形成SO4-Ca(Ca·Na)型高矿化度水(TDS可达2.5 g/L以上)。平面上:浅层地下水水化学特征受地形地势、人为污染、局部区域石膏层埋深变浅等因素影响,但总体上水质较好,可作为当地居民的生活饮用水;深层地下水主要受地层石膏埋藏深度变化的影响,地下水水化学类型和矿化度的空间差异较大。通过水文地球化学模拟定量分析了地下水平面和垂向上的差异,所得结果与实际情况基本吻合。研究成果可为岷江流域含石膏地层区地下水水化学特征分析提供科学依据。

成都平原农田蔬菜重金属含量及污染评价

为降低重金属污染风险,保证蔬菜生产安全,调查了成都平原部分污染地区蔬菜种植地土壤和5类18种蔬菜可食部位重金属含量,并对蔬菜中重金属污染状况进行了评价,同时运用富集系数分析和比较了不同蔬菜对Cd、Cr、Pb、Zn、Cu、Ni、Hg、As的富集能力。结果表明:试验区域土壤Cd含量超标率达31.91%,Cd是主要污染物,其余元素均符合国家标准。所有蔬菜可食部位主要受重金属Cr、Hg、Cd污染,轻微污染的有蒜苗和油菜,轻度污染的有菠菜和香菜;通过富集系数发现,18种蔬菜对8种重金属元素的富集系数平均值均从高到低依次为Cd>Zn>Hg>Cu>Ni>As>Cr>Pb,且不同蔬菜对同一种元素的富集系数也表现显著性差异。总体上,叶菜类蔬菜如香菜对Cd、Hg、Pb、Cr、Ni、Zn、Cu和菠菜对Cd、Hg、Zn、Pb、Cu以及红油菜对As、Pb富集能力相对较强,表明研究区域香菜和菠菜不宜在Cd、Hg、Pb、Cr、Ni、Zn、Cu污染土壤上栽培,及红油菜不宜在As、Pb污染土壤上栽培,而甘蓝类和根茎类如包心菜对Cd、Hg、Cr、Pb、As、Ni、Cu和白萝卜对Cd、Cr、Zn、Cu、Ni、Hg及红萝卜对Zn、Cr、Cu富集能力则相对较弱,可作为研究区域Cd、Hg、Cr、Pb、As、Ni、Cu、Zn污染土壤优先选种的蔬菜品种。