基于自然资源价值理论的自然岸线价值核算——以辽宁省大连市为例

以自然资源价值理论为指导,构建以使用价值和生态价值为基础的自然岸线资源二元价值结构。结果表明：通过建立自然岸线资源物质量与价值量核算方法,得出大连市自然岸线资源物质总量为766.6 km,全市自然保有率为46.9%。到“十四五”末,大连市海岸线资源价值总量约1 792.88亿元,自然资源岸线价值组成中生态价值占主导地位,价值量占比为99.8%。该核算方法实现了自然岸线资源生态价值的内部化过程,解决了岸线资源的价值以使用价值为主、对生态价值的忽视或考虑不足、导致整体价值被低估的核心问题。过度的资源开发是造成自然岸线资源稀缺的原因,加之资源保护与开发的高质量发展模式,自然岸线资源价值将不断攀高。自然岸线资源价值也将成为沿海地区核心价值的重要组成部分。     

克氏原鳌虾气象因子影响研究现状与展望

克氏原螯虾主要养殖在长江中下游地区,目前最主要的养殖模式为虾稻共作模式。大量研究结果表明,克氏原螯虾的生长发育与气象要素密切相关。水温在25-30℃时,克氏原螯虾生长较快;16-25℃水温范围内,温度越高,越有利于雌虾卵巢发育;20-30℃水温范围内,水温越高,受精卵孵化时间越短。光明和黑暗时间之比为16 h∶8 h时,最有利于雌虾性腺发育。与克氏原螯虾养殖有关的气象灾害主要有暴雨洪涝、高温热害、低温冷害。鉴于目前的养殖和气象因子影响研究及服务现状,建议气象部门开展虾-稻种养基地气象观测站网建设,开展气温与水温相关性和水温预报研究,以及气象要素对克氏原螯虾影响的定量化研究。     

丝绸之路遗产诠释与重游意愿影响关系研究

为探究世界遗产丝绸之路沿线遗址点遗产诠释与重游意愿的影响关系,研究将遗产诠释分为现场遗产解说与非现场遗产传播两部分,并以旅游体验为中介变量,游客特征为调节变量,构建“遗产诠释-旅游体验-重游意愿”的结构关系模型。研究表明：（1）非现场遗产传播正向影响现场遗产解说;（2）遗产诠释需要通过深刻的旅游体验才能更好地影响重游意愿;（3）遗产诠释与重游意愿的影响关系部分受游客性别和文化程度的调节,其中非现场遗产传播更能在高文化程度的游客中发挥其对重游意愿的影响作用,同时更能在男性游客中发挥其对旅游体验的影响作用。     

Mapping Geochemical Anomalies Through Integrating Random Forest and Metric Learning Methods

Extracting geochemical anomalies from geochemical exploration data is one of the most important activities in mineral exploration. Geochemical anomaly detection can be regarded as a binary classification problem. The similarity between geochemical samples can be measured by their distance. The key issue of this classification is to find the intrinsic relationship and distance between geochemical samples to separate geochemical anomalies from background. In this paper, a hybrid method that integrates random forest and metric learning (RFML) is used to identify geochemical anomalies related to Fe-polymetallic mineralization in Southwest Fujian Province of China. RFML does not require any specific statistical assumption on geochemical data, nor does it depend on sufficient known mineral occurrences as the prior knowledge. The geochemical anomaly map obtained by the RFML method showed that the known Fe deposits and the generated geochemical anomaly area have strong spatial association. Meanwhile, the receiver operating characteristic curves for the results of RFML and another method, namely maximum margin metric learning, indicated that the RFML method exhibited better performance, suggesting that RFML can be effectively applied to recognize geochemical anomalies.

     

A bounding surface model for anisotropically overconsolidated clay incorporating thermodynamics admissible rotational hardening rule

A bounding surface model is formulated to simulate the behavior of clays that are subject to an anisotropic consolidation stress history. Conventional rotational hardening is revisited from the perspective of thermodynamics. As the free energy cannot be accumulated infinitely upon critical state failure, the deviatoric back stress must vanish. This requires the rotated yield surface to be turned back to eventually align on the hydrostatic axis in the stress plane. Noting that most of the previous propositions violate this restriction, an innovative rotational hardening rule is formulated that is thermodynamically admissible. The bounding surface framework that employs the modified yield surface is applied to simulate elastoplastic deformations for overconsolidated clays, with which the overprediction of strength on the “dry” side can be greatly improved with reasonable results. Other important features, including contractive or dilative response and hardening or softening behavior, can also be well-captured. It has been shown that the model can simulate three types of reconstituted clays that are sheared with initial conditions over a wide range of anisotropic consolidation stress ratios and overconsolidation ratios under both triaxial undrained and drained conditions. Limitations and potential improvement of the model regarding the fabric anisotropy at critical state have been discussed.     

富营养化湖泊蓝藻—芦苇碎屑堆积分解过程及其潜在的共代谢效应

为探究富营养化浅水湖泊所富集的有机物对湖泊碳循环和水质的影响,本研究构建微宇宙系统,模拟蓝藻和芦苇碎屑单独分解及混合分解过程.通过测定各组上覆水营养盐浓度、有机质含量及结构的变化,揭示富营养化湖泊藻草残体混合分解过程中养分和有机碳的释放特征.结果 表明,在实验0～88 h内,在添加相同的碳源条件下,蓝藻和芦苇混合处理组...     

Changes in soil organic carbon stocks as affected by cropping systems and cropping duration in China’s paddy fields: a meta-analysis

Great uncertainties remain in the impact of cropping systems on soil organic carbon (SOC) stocks in paddy fields that hold a large potential for carbon (C) sequestration. In this study, a meta-analysis was performed to examine trends on SOC stocks in unfertilized and fertilized fields from three of the most common rice cropping systems in China. Results showed that rice cropping without any nutrient application (Control) significantly increased SOC stocks by 9% compared to the initial level in double rice cropping systems (DR), whereas no significant effects were observed in single rice cropping systems (SR) and rice-upland crop rotation systems (RU). Paddy soils sequestered C in all the three cropping systems under inorganic NPK fertilization, and the magnitude of the increase in SOC stocks was in the order DR > RU > SR. Soil C stocks increased with the increasing cropping duration. Continuous rice cropping for more than 20?years led to average SOC gains of 15% and 23% in the control and NPK treatments, respectively. Furthermore, it seems that C sequestration was still occurring in the longest fields from the included studies. Thus, no SOC saturation trend was found over the investigated cropping duration. However, the negative relationship between SOC changes and their initial C stocks suggests indirectly the possibility of SOC saturation in paddy fields.     

横流环境中水下溢油输移扩散的实验研究

文章基于自制的组合式环形水槽（周长9.7 m、宽0.45 m、深1.0 m）,分别以阿曼原油及其消油剂混合物和淡水（含示踪剂）为模拟污染物,开展水下溢油的物理模拟实验,以浮射流输移轨迹、污染物扩散范围和油滴粒径分布为考察指标,研究横流环境和消油剂的使用对水下溢油输移扩散的影响。实验结果表明:在横流环境中,浮射流输移轨迹开始弯曲的高度随着流速的增加而降低;与淡水浮射流主要在水中输移扩散的情况不同,当污染物为原油时,大粒径油滴脱离浮射流主体并上浮至水面,导致扩散范围更大;消油剂的添加会使原油浮射流内部油滴的体积中值粒径变小,油滴粒径分布曲线向小尺寸方向偏移。实验结果可为后续的物理模拟实验和数值模拟研究提供参考。     

鄂尔多斯盆地庆城地区延长组7段致密油特征及油源分析

鄂尔多斯盆地三叠系延长组7段(长7段)半深湖—深湖相优质油源岩是油气的重要来源,包括黑色页岩和暗色泥岩,作为盆地重要的供烃源岩一直是研究的热点。为了明确不同烃源岩的贡献及油气来源,通过对庆城地区长7段致密油特征进行分析,对原油进行精细划分,并对源岩有效性进行分析,进一步明确油源对应关系,研究表明,庆城地区长7段黑色页岩和暗色泥岩均对油气成藏有贡献,其中黑色页岩贡献最大,长7₃段暗色泥岩次之,长7₂和长7₁段暗色泥岩贡献较小;原油为低密度、中—低黏度和低凝固点的轻质油。根据生标物特征将原油划分为3类,A类原油具有低C₃₀重排藿烷/C₂₉藿烷、低C₂₉Ts/C₂₉藿烷、低Ts/Tm的特征,由黑色页岩贡献,主要分布于长7₁段;C类原油具有高C₃₀重排藿烷/C₂₉藿烷、高C₂₉Ts/C₂₉藿烷、高Ts/Tm的特征,主要由暗色泥岩贡献,...     

Low post-Cenomanian denudation depths across the Brazilian Northeast: Implications for long-term landscape evolution at a transform continental margin

The Brazilian Northeast affords good opportunities for obtaining reliable timings and rates of landscape evolution based on stratigraphic correlations across a vast region. The landscape formed in the context of an episodically fluctuating but continuously falling base level since the Cenomanian. After formation of the transform passive margin in Aptian times, landscape development was further driven by a swell-like uplift with its crest situated  300 km from the coastline. The seaward flank of this swell or broad monocline between the interior Araripe and coastal Potiguar basins was eroded, and currently forms a deeply embayed plain bordered by a semi-circular, north-facing erosional escarpment. The post-Cenomanian uplift caused an inversion of the Cretaceous basins and generated a landscape in which the most elevated landforms correspond either to resistant Mesozoic sedimentary caprock, or to eroded stumps of syn-rift Cretaceous footwall uplands. Denudation in the last 90 My never exceeded mean rates of 10 m·My^− 1 and exhumed a number of Cretaceous stratigraphic unconformities. As a result, some topographic surfaces at low elevations are effectively Mesozoic land surfaces that became re-exposed in Cenozoic times. The Neogene Barreiras Formation forms a continuous and mostly clastic apron near the coast. It testifies to the last peak of erosion in the hinterland and coincided with the onset of more arid climates at  13 Ma or earlier. The semi-circular escarpment is not directly related to the initial breakup rift flanks, which had been mostly eroded before the end of the Mesozoic, but the cause and exact timing of post-Cenomanian crustal upwarping are poorly constrained. It could perhaps have been a flexural response of the low-rigidity lithosphere to sediment loads on the margin, and thus a slowly ongoing process since the late Cretaceous. Uplift could instead be the consequence of a more discrete dynamic event related either to Oligocene magmatism in the region, or to continental-scale far-field stresses determined by Andean convergence.