珠江三角洲陈村钻孔剖面沉积特征及有机碳同位素古环境意义

陈村剖面位于佛山市陈村镇。AMS14C及OSL测年结果显示,剖面自晚更新世中晚期以来开始沉积,结束于全新世晚期,由老至新经历了河流相—河口湾相—三角洲相沉积环境。根据有机碳同位素曲线变化特征,结合孢粉、有孔虫等鉴定结果及沉积环境综合分析,将剖面划分为4个演化阶段:1晚更新世,34.15~24.5ka BP,属河流相沉积环境,δ13Corg平均值为-28.13‰,对应MIS 3期冷—稍湿气候,期间小幅波动;2晚更新世—全新世早期,24.5~9ka BP,属河流相沉积环境,δ13Corg平均值为-29.8‰,对应MIS 2期干冷气候及全新世早期温—干气候,YD事件得以记录;3全新世早—中期,9~6.7ka BP,属于河口湾—三角洲相沉积环境,δ13Corg平均值为-27.97‰,变化幅度小,对应暖—湿气候;4全新世中—晚期,6.7~0.44ka BP,属于三角洲相沉积环境,δ13Corg平均值为-26.94‰,变化幅度大,冷暖变化显著,气候特征为热湿—偏凉—暖干。     

Piezomagnetic In-situ Stress Monitoring and its Application in the Longmenshan Fault Zone

The relative change of in-situ stress is an inevitable outcome of differential movement among the crust plates. Conversely, changes of in-situ stress can also lead to deformation and instability of crustal rock mass, trigger activity of faults, and induce earthquakes. Hence, monitoring real-time change of in-situ stress is of great significance. Piezomagnetic in-situ stress monitoring has good and longtime applications in large engineering constructions and geoscience study fields in China. In this paper, the new piezomagnetic in-situ stress monitoring system is introduced and it not only has overall improvements in measuring cell＇s structure and property, stressing and orienting way, but also enhances integration and intelligence of control and data transmission system, in general, which greatly promotes installing efficiency of measuring probe and quality of monitoring data. This paper also discusses the responses of new piezomagnetic system in large earthquake events of in-situ stress monitoring station at Qiaoqi of Baoxing and Wenxian of Gansu. The monitoring data reflect adjustments and changes of tectonic stress field at the southwestern segment of and the northern area near the Longmenshan fault zone, which shows that the new system has a good performance and application prospect in the geoscience field. Data of the Qiaoqi stress-monitoring station manifest that the Lushan Earthquake did not release stress of the southwestern segment of the Longmenshan fault zone adequately and there still probably exists seismic risk in this region in the future. Combined with absolute in-situ stress measurement, carrying out long-term in-situ stress monitoring in typical tectonic position of important regions is of great importance for researchers to assess and study regional crust stability.     

Deep incision in an Aptian carbonate succession indicates major sea‐level fall in the Cretaceous

Long‐term relative sea‐level cycles (0·5 to 6 Myr) have yet to be fully understood for the Cretaceous. During the Aptian, in the northern Maestrat Basin (Eastern Iberian Peninsula), fault‐controlled subsidence created depositional space, but eustasy governed changes in depositional trends. Relative sea‐level history was reconstructed by sequence stratigraphic analysis. Two forced regressive stages of relative sea‐level were recognized within three depositional sequences. The first stage is late Early Aptian age (intra Dufrenoyia furcata Zone) and is characterized by foreshore to upper shoreface sedimentary wedges, which occur detached from a highstand carbonate platform, and were deposited above basin marls. The amplitude of relative sea‐level drop was in the order of tens of metres, with a duration of <1 Myr. The second stage of relative sea‐level fall occurred within the Late Aptian and is recorded by an incised valley that, when restored to its pre‐contractional attitude, was >2 km wide and cut ≥115 m down into the underlying Aptian succession. With the subsequent transgression, the incision was backfilled with peritidal to shallow subtidal deposits. The changes in depositional trends, lithofacies evolution and geometric relation of the stratigraphic units characterized are similar to those observed in coeval rocks within the Maestrat Basin, as well as in other correlative basins elsewhere. The pace and magnitude of the two relative sea‐level drops identified fall within the glacio‐eustatic domain. In the Maestrat Basin, terrestrial palynological studies provide evidence that the late Early and Late Aptian climate was cooler than the earliest part of the Early Aptian and the Albian Stage, which were characterized by warmer environmental conditions. The outcrops documented here are significant because they preserve the results of Aptian long‐term sea‐level trends that are often only recognizable on larger scales (i.e. seismic), such as for the Arabian Plate.     

Stable C and N isotope record of short term changes in water level in lakes of different morphometry: Lake Anastazewo and Lake Skulskie,central Poland

We present the stable C isotope record of the changes within the past 20 yr in water level of two morphologically different lakes in central Poland. The aim was to explain the relationship between lake water level and the δ¹³C signature of bulk sedimentary organic matter (δ¹³C_TOC) and to assess the potential of δ¹³C_TOC as a paleolimnological proxy of lake level change. This was done by comparison of the fossil δ¹³C_TOC record with instrumental data for lake level change in a shallow and small lake as well as in one large and deep basin. In both lakes the water table varied greatly between 1980 and 2000 AD. The δ¹³C_TOC data were supplemented with δ¹⁵N and bulk geochemistry data, as well as paleoecological data. We show that δ¹³C_TOC reacted to short term and low amplitude fluctuation in water level, but the response was highly dependent on the morphometry of the lake. In the shallow and small basin, δ¹³C_TOC decreased along with lake level drop due to oxidation and greater input of organic matter from macrophytes colonizing the lake bottom. On the contrary, in the deep/large lake δ¹³C_TOC decreased with increasing water level due to enhanced delivery of soil-derived OM to the lake during highstands. Our results have broad paleolimnological implications as they show that δ¹³C_TOC cannot act as a universal paleohydrological proxy. Its interpretation for a particular lake can be ambiguous and must be supported with additional geochemical and paleocological information.     

粤港澳大湾区红树林长时间序列遥感监测

随着遥感数据量的爆发式增长,对变化过程分析的精细化要求与本地算力不足之间的矛盾日益突出。GEE（Google Earth Engine）地理云平台的出现,解决了用户算力紧张的行业痛点。本文以粤港澳大湾区为研究区,在GEE的支持下,构建1987年—2020年年度湿地分类数据集,分析大湾区红树林的时间阶段性特征和空间扩张过程,结合连续长历时分析对变化时间点的准确识别,揭示了保护区设立与滩涂造林等工程在红树林保护与修复中的积极成效。主要结论有：（1）截止到2020年,大湾区共有红树林2174 ha,81%的红树林集中在深圳湾、淇澳岛和镇海湾;（2）大湾区的红树林经历了由平稳发展（1987年—2003年）到快速增长（2003年—2020年）的变化过程,其主要增量来源于镇海湾（40%）和淇澳岛（28%）;（3）淇澳岛和镇海湾的红树林仍处于快速增长期,但淇澳岛增速最快,从2002年至今面积翻了30倍,深圳湾则在早期的快速增长（1987年—2009年）后进入平稳期（2009年—2020年）;（4）由于保护区设立时间较早,深圳湾成为大湾区唯一一个形成稳定核心区的红树林分布区,镇海湾虽然拥有最大的红树林面积,但林道狭窄,景观破碎,生态系统反而更加脆弱;（5）设立自然保护区和滩涂造林都对红树林面积增长起到了积极作用。本研究为大湾区海岸带湿地生态系统保护与修复提供科学的证据支持,对沿海生态屏障建设具有一定的指导作用。     

Long-term and monthly changes in abundance,size composition and spatial distribution of the mantis shrimp Oratosquilla oratoria in the Bohai Sea

With the decline in fish resources worldwide, the ecological dominance and economic importance of crustaceans have obviously increased. Among crustacean species, mantis shrimps are increasingly dominant in many coastal waters of the world. In China, Oratosquilla oratoria is the most widely distributed and productive species of mantis shrimp, and its relative resource density is the highest in the Bohai Sea. In this study, we analysed the long-term and monthly population characteristics of O. oratoria in the Bohai Sea, including its relative resource density, body size and spatial distribution. The results showed that the relative resource density of O. oratoria in the Bohai Sea increased from 3.59 kg/h in 1982 to 14.48 kg/h in 2018, and the percentage of this species that serves as a fishery resource increased from 4.22% in 1982 to 35.27% in 2018, based on the mean relative resource density in May and August. The relative resource density of O. oratoria in the fishing moratorium season from May to August was significantly higher than that in the other months of fishing season, and the relative resource density decreased rapidly after the fishing moratorium ended. The relative resource density of O. oratoria was the highest in summer (August), followed by in autumn (October) and spring (May), and it was the lowest in winter (January). The relative resource density of O. oratoria in the western Bohai Sea was higher than that in the eastern Bohai Sea. The mean body weight of O. oratoria in the Bohai Sea decreased from 21.95 g in 1982 to 14.34 g in 2018, based on the mean body weight in May and August. The body size of O. oratoria in the fishing moratorium season was significantly higher than that in the fishing season, and the body size decreased rapidly after the fishing moratorium ended. Overall, in the context of declining resources of most fishery species, the relative resource density of O. oratoria increased due to its hardiness and adaptability, and its body size decreased under intensive fishing over the past 30 years. The fishing moratorium system had a great influence on the population dynamics of O. oratoria in terms of the relative resource density and body size in the Bohai Sea.     

2019年夏秋季温州近海海水透明胞外聚合颗粒物（TEP）的分布及影响因素分析

透明胞外聚合颗粒物（TEP）具有高黏性、低密度和高碳氮比等特性,在颗粒有机物的聚集以及食物网循环中发挥着重要作用。为了解近岸海域TEP的分布动力学规律与机制,本文对温州近海夏秋季节水体中透明胞外聚合颗粒物的分布进行调查,并结合多项环境要素的主成分分析与相关性分析,探究了浙江南部近岸海域TEP分布的影响因素。结果显示,温州近海TEP秋季平均含量明显高于夏季,夏季TEP分布变化主要受陆地径流（瓯江）作用影响,而秋季主要受闽浙沿岸流影响。受沿岸流影响,秋季TEP的主要来源可能是其他海域以及底层颗粒物再悬浮。此外,由浮游植物释放的TEP对夏季的POC贡献最大,而秋季外源性TEP对POC的贡献较夏季有所升高。     

钦州湾人工海滩剖面变化过程

波浪和潮汐作用下的海滩剖面动态变化过程是海岸演变及沿海防护工程设计与旅游资源规划的核心内容。本文以广西钦州湾沙井半岛人工海滩为研究区, 基于GPS-RTK采集的2018年1月—2019年12月的逐月剖面高程实测数据, 通过分析剖面冲淤和单宽体积变化, 利用EOF(Empirical Orthogonal Function)函数揭示剖面的高程变化模式, 进而探讨海滩剖面的动态演变过程。研究的主要结果表明: 1) 在观测期间, 人工海滩剖面的冲淤情况整体展现出冬春季淤积、夏秋季侵蚀的变化特征; 2) 人工海滩剖面因泥沙横向输移而导致不同横向分带的单宽体积变化趋势呈差异性, 不同横向分带具有侵蚀与淤积交替出现的情况; 3) 人工海滩剖面的变化模式可划分为由强降雨及台风导致剖面高程明显降低的主要模式、波潮影响下的剖面高程经历强降雨及台风后逐渐淤积和恢复的次要模式、波浪破碎形成卷流引起滩面冲淤变化的其他模式。     

黄河流域绿色发展效率的时空演变特征与影响因素

基于2005—2017年黄河流域61个地级市数据,构建了黄河流域绿色发展效率投入产出指标体系,并运用多种计量方法研究了黄河流域绿色发展效率时空格局特征与驱动因素。结果如下：① 黄河流域绿色发展效率的区域差距不断扩大,研究期限内绿色发展效率呈现出由“高效率小差距”向“低效率大差距”演进,说明黄河流域绿色发展效率的俱乐部收敛特征不断凸显。② 黄河流域绿色发展效率增长主要来源于规模效率的贡献,科学技术尚未发挥重要驱动作用。③ 研究期限内黄河流域绿色发展效率存在较为明显的空间依存关系,绿色发展效率水平相近的地区空间集聚现象显著。④ 黄河流域绿色发展效率空间分异性显著,高效率地区的东西分布、南北分布的地域差异性突出,集中表现在以城市群为载体呈集群式发展。最后采用Tobit回归模型具体分析了产业结构、经济发展、科学技术、政府调控与市场化水平对于黄河流域及上中下游地区绿色发展效率的作用强度与作用效果。     

2000—2018年内蒙古长爪沙鼠疫源地地表景观特征及变化

鼠疫疫源地的环境变化对鼠疫的传播扩散具有重要影响。本文基于2000年、2005年、2010年、2015年及2018年五期土地利用和年最大化合成NDVI数据,选取斑块面积占比、景观形状指数、最大斑块比例和斑块破碎度、周长面积分维数、蔓延度指数、多样性指数、均匀指数及聚集指数,定量分析了内蒙古长爪沙鼠疫源地土地利用格局和植被格局的结构特征及演变规律。结果表明：① 2000—2015年,内蒙古长爪沙鼠疫源地内土地利用整体稳定,变化较小,2015年后变化较大,主要表现为不同草地之间的转换。② 2000年、2005年、2010年、2015年NDVI介于（0.056,0.37]的草地在疫源地内占据主体地位,面积占比分别为77.45%、83.61%、83.03%和82.47%。到2018年,该类草地面积显著减少,面积占比下降到48.44%。与之对应,2000—2015年,NDVI介于（0.37,0.83]的草地面积占比为22.54%、16.39%、16.96%和17.4%,而2018年,该类草地的面积显著增加到51.34%。③ 2000—2015年,各草地类别表现出类内高聚集分布,类间分界明显的特征。到2018年,各类别草地向多个方向扩散,并在整个疫源地内趋于均衡分布,植被类内连通性增加,类间分界逐渐平滑。该变化使得内蒙古鼠疫流行风险呈增加态势。本研究对厘清长爪沙鼠疫源地地表景观和生态环境的变化、预测鼠疫潜在风险、预防人间鼠疫暴发具有科学参考价值。