人才流动的空间特征、驱动因素及其对长三角一体化高质量发展的启示——基于高校毕业生的分析

2018年长三角一体化发展上升为国家战略,旨在以一体化的思路和举措打破行政壁垒,实现资金、人才、技术等要素资源的畅通流动。人才作为知识经济时代创新和发展的主要动力,其合理分布和有序流动对于推动长三角一体化和实现高质量发展具有重要意义。聚焦高校毕业生这一重要区域人才资源,基于毕业生就业质量报告数据,刻画长三角高校毕业生流动的空间格局,使用地理探测器探索城市创新等因素对毕业生流动的影响。研究结果表明：（1）长三角高校毕业生流动基本遵循随距离衰减和等级跃迁规律,区域内就业占比高达79.72%。江苏、浙江、安徽呈现出差异化的省内流动空间形态。（2）位于“Z”型发达地带和沿海的城市毕业生粘滞率较高,上海和与其紧邻的苏州、嘉兴、南通形成“高—高”区。（3）因子探测结果显示,创新因素对毕业生流动的驱动力较强,但按省域来看,驱动作用在江苏最强,浙江次之,而在安徽并不显著。风险探测显示,创新因素的驱动存在阈值效应。研究揭示了高校毕业生的流动格局及与城市创新的关系,为推动区域人才一体化政策的制定提供了理论和实证依据。     

Optimism and Challenge for Science‐Based Conservation of Migratory Species in and out of U.S. National Parks

Public agencies sometimes seek outside guidance when capacity to achieve their mission is limited. Through a cooperative agreement and collaborations with the U.S. National Park Service (NPS), we developed recommendations for a conservation program for migratory species. Although NPS manages ～36 million hectares of land and water in 401 units, there is no centralized program to conserve wild animals reliant on NPS units that also migrate hundreds to thousands of kilometers beyond parks. Migrations are imperiled by habitat destruction, unsustainable harvest, climate change, and other impediments. A successful program to counter these challenges requires public support, national and international outreach, and flourishing migrant populations. We recommended two initial steps. First, in the short term, launch or build on a suite of projects for high‐profile migratory species that can serve as proof to demonstrate the centrality of NPS units to conservation at different scales. Second, over the longer term, build new capacity to conserve migratory species. Capacity building will entail increasing the limited knowledge among park staff about how and where species or populations migrate, conditions that enable migration, and identifying species’ needs and resolving them both within and beyond parks. Building capacity will also require ensuring that park superintendents and staff at all levels support conservation beyond statutory borders. Until additional diverse stakeholders and a broader American public realize what can be lost and do more to protect it and engage more with land management agencies to implement actions that facilitate conservation, long distance migrations are increasingly likely to become phenomena of the past. Optimismo y Retos para la Conservación Científicamente Basada de Especies Migratorias Dentro y Fuera de Parques Nacionales de E.U.A.     

Study on the influencing factors of peasants’ subjective well-being

On the basis of data collected from Liupanshan poverty-ridden areas, the paper selects 24 variables under 4 groups to figure out the influencing factors of subjective well-being (SWB) of peasants in ecological migration with the method of Ordered Probit Regression. As is shown in the results, variables under peasants’ personal endowment group and resource of the development group have little impact on peasants’ SWB. The variables with observable impact are concentrated in the living condition group and the public atmosphere group.     

Phenological mismatch and the effectiveness of assisted gene flow

The persistence of narrowly adapted species under climate change will depend on their ability to migrate apace with their historical climatic envelope or to adapt in place to maintain fitness. This second path to persistence can only occur if there is sufficient genetic variance for response to new selection regimes. Inadequate levels of genetic variation can be remedied through assisted gene flow (AGF), that is the intentional introduction of individuals genetically adapted to localities with historic climates similar to the current or future climate experienced by the resident population. However, the timing of reproduction is frequently adapted to local conditions. Phenological mismatch between residents and migrants can reduce resident × migrant mating frequencies, slowing the introgression of migrant alleles into the resident genetic background and impeding evolutionary rescue efforts. Focusing on plants, we devised a method to estimate the frequency of resident × migrant matings based on flowering schedules and applied it in an experiment that mimicked the first generation of an AGF program with Chamaecrista fasciculata, a prairie annual, under current and expected future temperature regimes. Phenological mismatch reduced the potential for resident × migrant matings by 40–90%, regardless of thermal treatment. The most successful migrant sires were the most resident like in their flowering time, further biasing the genetic admixture between resident and migrant populations. Other loci contributing to local adaptation—heat‐tolerance genes, for instance—may be in linkage disequilibrium with phenology when residents and migrants are combined into a single mating pool. Thus, introgression of potentially adaptive migrant alleles into the resident genetic background is slowed when selection acts against migrant phenology. Successful AGF programs may require sustained high immigration rates or preliminary breeding programs when phenologically matched migrant source populations are unavailable.     

水源水库暴雨径流过程水体锰的迁移及其影响

针对西安金盆水库2017年汛期出现的锰浓度超标问题,对水库上游至主库区沿程多个监测点垂向锰浓度及其赋存形态进行监测,研究暴雨径流对水中锰含量的影响以及径流中锰的形态,估算单次典型暴雨径流过程水库水体锰的汇入、输出与沉积量,根据实测数据与计算结果,从运行调度角度提出了暴雨时期高浊、高负荷径流入库的规避方案.结果表明,强降雨过程引起的高浊径流汇入显著增加了西安金盆水库水体总锰浓度,导致水库水质严重恶化,2017年10月12日至2017年10月14日单次降雨径流总锰的输入负荷为9. 11 t,泄洪和出水输出的总锰为6. 22 t,净沉积量(锰)为1. 47 t.水库上游沿程水体锰含量及形态变化表明,连续降雨过程对土壤的冲刷和侵蚀作用导致大量颗粒态污染物随径流汇入水体,占水体中总锰的质量分数大于70%,铁锰氧化物结合态为其主要形态.通过与不同粒径范围的颗粒进行相关性分析,颗粒态锰粒径约为2～20μm.暴雨径流入库时期采取泄洪排浊的措施可以有效减小锰的污染负荷,降低供水安全风险.     

微塑料的形成机制及其环境分布特征研究进展

塑料制品的广泛应用使塑料废弃物对生态环境的危害日益显著,也是全球环境问题关注的热点,由于缺乏完善的塑料废弃物管理体系,大部分塑料废弃物仍按传统模式处理或滞留在环境中,回收利用效率低,尚未形成塑料生命周期循环.环境中的塑料在长期受到物理、化学和生物等多种因素作用后会发生老化降解,形成微(纳)米塑料;由于它们粒径小、比表面积大且带有电荷等特性,除本身具有毒性外,还能作为重金属、持久性有机污染物等其他污染物的载体或被载体,经径流、污水排放和水文气象等多种途径在环境中迁移,造成生态环境污染.微塑料(MPs)分布范围广,全球的水体(淡水、海洋)、土壤和大气环境中均存在不同程度的MPs污染,近些年甚至在人体胎盘、母乳、活人肺部和血液中也发现了MPs的踪迹.因此对国内外MPs在物理、化学和微生物作用下的形成机制及其在水体、土壤和大气环境中的丰度水平、迁移特征进行全面地综述,为监测环境中MPs的污染水平、探究其在环境中的运移规律、提出MPs污染环境治理策略和揭示MPs在不同作用下的降解机制提供资料参考.     

融冰过程中铁离子和锰离子的迁移规律

为探究融冰过程中重金属离子的迁移规律,选择铁离子和锰离子为研究对象,开展了室内模拟融冰实验,探讨其在融冰过程中的迁移规律,并分析初始浓度和冷冻温度对其迁移过程的影响.结果表明：在不同的初始浓度和冷冻温度条件下,铁离子和锰离子在冰中各层的浓度分布关系皆为：中层 < 上层 < 下层;融冰过程中,51.17%~71.67%的铁离子和锰离子均在冰体融化前期（0~25%）集中释放,中后期相对平稳均匀释放,此外初始浓度对冰融化时铁离子和锰离子的迁移规律影响不大,而冷冻温度较低时,融1中铁离子和锰离子的浓度基本在增加;融冰过程中,随着累积融水体积的增加,融水中铁离子和锰离子的浓度与冰体初始浓度之比逐渐降低,它们之间呈指数函数衰减模式.     

特殊地质条件下流动相原油在沿海土-水系统中的运移过程及机制研究

原油作为主要能源之一对现代社会的重要作用不言而喻,但其所带来的污染危害同样不容忽视.通过自制的有机玻璃水槽,建立模型模拟自然地层的非均质性,模拟了原油在沿海土-水系统中的运移过程,探讨了局部非渗透性透镜体、底部隔水层、土壤初始含水率、土壤质地、岩性突变界面对原油在砂土中运移速度和路径的影响.结果表明,局部非渗透性透镜体和底部隔水层对原油的运移具有阻碍作用,会改变其运动速度和路径.在一定范围内,土壤初始含水率越高,原油的侧向运移速率和垂向运移速率越大(模拟成层性土层中原油垂向运移速率随含水率增大,由0.43 cm·min~(-1)增大到1.00 cm·min~(-1),在低含水率区域原油侧向运移速率分别为0.08 cm·min~(-1)(粗-细界面)和0.10 cm·min~(-1)(细-粗界面),而在含水率较高的区域则为0.14 cm·min~(-1)),而过高的含水率又会阻碍原油的运移.土壤孔隙越大,垂向运移越快,侧向运移越慢,反之,垂向运移越慢,侧向运移越快(模拟成层性土层中,原油在粗砂中的垂向平均运移速率为0.54 cm·min~(-1),而在细砂中仅为0.33 cm·min~(-1),自然泄漏时原油在粗砂中的最大扩散范围为9.10 cm,在细砂中为12.50 cm).原油在土壤中运移遇到岩性突变界面时,会产生聚集效应,在聚集处产生侧向运移,试验中在粗-细界面扩散宽度为6.70 cm,在细-粗界面扩散宽度为29.00 cm.     

有机碳含量对土壤剖面中多环芳烃纵向迁移的影响

为探索有机碳含量对土壤剖面中多环芳烃(PAHs)纵向迁移的影响,选取北京地区3条有机碳(TOC)含量明显不同的土壤剖面进行了土柱淋滤实验研究.结果表明,通过30 d(相当于北京地区3年的淋滤水量)的淋滤实验后,不同剖面中PAHs均存在不同程度的迁移现象,但剖面中残留的PAHs仍然主要富集在土柱表层0～30 cm土壤中,且中高环数PAHs的残留率明显高于低环数PAHs.TOC含量与PAHs的残留总量之间具有显著的正相关性,TOC含量越高,PAHs残留量越高.此外,TOC对不同环数PAHs迁移的影响程度存在差别,高环数PAHs受TOC变化的影响高于低环数PAHs.     

4种NAPLs污染物在二维砂箱中的指进锋面形态特征研究

为明确介质和流体性质等因素对非水相液体(NAPLs)在多孔介质中入渗迁移的影响,利用数码图像分析技术对甲苯、柴油、1,2-二氯乙烷和四氯乙烯这4种NAPLs在4种不同粒径多孔介质中的非饱和入渗特性进行了实验研究.结果表明,数码图像分析技术能够动态、全过程记录NAPLs的迁移锋面;NAPLs在驱替气体过程中会出现指进形式的不稳定流;指进生长过程中出现分叉、合并和屏蔽等现象;NAPLs的迁移特性受介质性质和流体特性的共同影响,入渗过程中垂向上的迁移速率和污染面积增长率与介质粒径大小呈正相关,与流体密度呈正相关(甲苯除外),入渗过程中形成的指进与介质和流体本身性质也密切相关.相同时间内,DNAPL相较于LNAPL入渗的距离更深,造成的污染面积更大,其环境风险明显大于LNAPL.