农业水生产力研究进展

文章系统阐述了农业水生产力概念的发展过程,综合分析了影响农业水生产力的主要因素,详细列举了不同尺度上评估农业水生产力所需的水流及产出计算方法,给出了4种主要农作物在全球范围内的水生产力的分布范围与空间格局,并从提高水分利用效率、加强田间水资源管理、选择适宜的种植模式和栽培技术以及培育更加高效的农作物品种4个方面全面综述了各种水生产力提高策略。指出在未来的水生产力研究中还需要强调农户的参与以及学科间的协作,加强水生产力尺度效应、水权与水价问题、虚拟水交易、水生产力提高措施对环境影响等方面的研究。     

薄互层地层震电波场响应特征

震电耦合产生的伴随震电场（CS）和震电界面场（IR）具有不同的强度,且能够反映地下地质体界面信息的震电界面响应一般较弱,而震电界面响应场可能在薄互层地质背景下能够出现较强的振幅值.目前还未有针对薄互层震电波场响应特征分析,且纵波引起的震电界面响应场是否对薄互层敏感有待探究.本文基于体积电荷密度的震电耦合理论数值模拟了平行薄互层（VTI）和倾斜薄互层（HTI）地质背景下的震电波场响应特征.结果表明,伴随纵波传播而产生的CS震电场几乎不受平行薄互层和楔形薄互层的影响.纵波在界面处诱导产生的IR震电场对垂直薄互层不敏感,但水平薄互层和楔形薄互层模型的厚度和薄互层的层数均能影响IR震电信号,薄互层单层厚度减小和薄互层层数增加会导致IR信号的增强.结果有力证明了纵波引起的震电界面响应场在薄互层地质体处会产生振幅异常,而水平和垂直薄互层的震电波场差异也有将助于探究层理方向有显著差异的页岩等储层中产生的震电信号.

     

CO2地下埋存分布状况及环境影响的监测

CO₂的地质埋存处理是减缓温室效应的现实选择之一。要保证埋存的有效性、安全性和持久性,需要对钻井（主要包括注入井和废弃井）、CO₂地下分布运移状况以及因CO₂渗漏所造成的环境影响等方面实施严格的监测管理。通过对以上各方面文献的查阅和综合分析,系统阐述了世界范围内目前CO₂地质埋存过程中所采用的各项主要监测技术。     

海洋环境中铁的来源、微生物作用过程及生态效应

铁在地壳中的含量位列第四,在海洋中常以微量元素的身份出现。铁拥有多变的价态和多样的功能,是调节海洋初级生产力和驱动海洋生物地球化学循环的重要力量。以往的研究表明,铁在维持初级生产力、耦合物质循环以及调节生源要素转化中具有重要作用。近年来微生物生态学的发展将铁的研究推向了新的高度,包括微生物驱动的铁氧化-还原行为、代谢过程以及与主要元素(C/N/P)的交互关系等。以近15年发表的文献为重点,尝试综述铁的最新进展。首先梳理了海洋中铁的来源和赋存状态(溶解态、胶体态、颗粒态和有机态);其次阐释了微生物介导的铁氧化还原类型和过程机制(如硝酸盐氧化、生物还原等);最后总结了铁与C/N/P循环的耦合关系以及在特定生态事件中的生态效应。此外,对海洋铁研究的“化学-生物-物理”理论框架也进行了展望,旨在为更好地认识铁循环及其在海洋微生态过程的作用提供资料借鉴。     

Cytological and Physiological Biomarker Responses from Green Mussels, Perna viridis (L.) Transplanted to Contaminated Sites in Hong Kong Coastal Waters

Biological monitoring of marine contaminants often involves the analysis of metals accumulated in mussel tissues. Critiques of this type of monitoring suggest that although relatively good indications of ambient metal concentrations are determined, actual biological harm is not elucidated. Biomarkers, techniques originally developed in medicine, have recently been employed in an attempt to ascertain the health of marine mussels. Biomarkers have been used with good effect in temperate marine pollution monitoring programmes. The use of biomarkers in the toxicological evaluation of tropical and subtropical waters is, however, generally lacking, which is somewhat surprising, as considerable industrialisation and environmental degradation is taking place in the Pacific-rim countries of Southeast Asia. In the present study, a suite of cytological and physiological biomarkers have been measured from mussels (Perna viridis: Mytilidae) transplanted within the coastal waters of Hong Kong. Mussels from contaminated sites, had labile lysosomal membranes, whereas animals from a cleaner reference site had more stable membranes. These cytological responses have been related to metal-induced stress and are simple, cost-effective markers of pollution. Cardiac activity from mussels transplanted to polluted sites was generally similar to that of individuals from the reference site, although a mild tachycardia was associated with one site. The cause of the tachycardia and the use of heart rate in mussels as a biomarker is discussed. Integrated physiological responses to stress, condition indices, revealed mussels from a clean reference site had higher indices than animals from contaminated sites. The relative sensitivities of the cytological and physiological biomarkers deployed in this study and their application to pollution monitoring is discussed.     

Articles 4.8 and 4.9 of the UNFCCC: adverse effects and the impacts of response measures

Abstract

Articles 4.8 and 4.9 of the United Nations Framework Convention on Climate Change (UNFCCC) and Article 3.14 of its Kyoto Protocol require parties to take measures to minimise the adverse effects of climate change on developing and least developed countries (LDCs). The Alliance of Small Island States (AOSIS) argue that this should mean assistance for capacity building to help them adapt to a changing climate. Articles 4.8 and 3.14 also require parties to take measures to minimise the impacts of emission reduction measures on energy exporting countries. The Organisation of Petroleum Exporting Countries (OPEC) countries argue that this should mean assistance to compensate for lost oil revenues. This paper explores the dimensions of the adverse effects/impacts issue. It explains how, in arguing that progress on Articles 4.8, 4.9 and 3.14 be equal to progress on the issue of assistance to compensate for lost oil revenues, OPEC countries obstruct progress on assistance to developing and LDCs for adaptation to climate change. This suggests that tacit G77/China support for OPEC's position may ultimately not be in their best interests. The paper discusses the outlook for the adverse effects/impacts of response measures issue.     

Global analysis of time-lag and -accumulation effects of climate on vegetation growth

Climate dominantly controls vegetation over most regions at most times, and vegetation responses to climate change are often asymmetric with temporal effects. However, systematic analysis of the time-lag and time-accumulation effects of climate on vegetation growth, has rarely been conducted, in particular for different vegetation growing phases. Thus, this study aimed to leverage normalized difference vegetation index (NDVI) to determine the spatiotemporal patterns of climatic effects on global vegetation growth considering various scenarios of time-lag and/or accumulation effects. The results showed that (i) climatic factors have time-lag and -accumulation effects as well as their combined effects on global vegetation growth for the whole growing season and its subphases (i.e., the growing and senescent phases). However, these effects vary with climatic factors, vegetation types, and regions. Compared with those of temperature, both precipitation and solar radiation display more significant time-accumulation effects in the whole growing season worldwide, but behave differently in the growing and senescent phases in the middle-high latitudes of the Northern Hemisphere; (ii) compared to the scenario without time effects, considering time-lag and -accumulation effects as well as their combined effects increased by 17 %, 15 %, and 19 % the overall explanatory power of vegetation growth by climate change for the whole growing season, the growing phase, and senescent phase, respectively; (iii) considering the time-lag and -accumulation effects as well as their combined effects, climate change controls 70 % of areas with a significant NDVI variation from 1982 to 2015, and the primary driving factor was temperature, followed by solar radiation and precipitation. This study highlights the significant time-lag and -accumulation effects of climatic factors on global vegetation growth. We suggest that these effects need to be incorporated into dynamic vegetation models to better understand vegetation growth under accelerating climate change.     

Demand modulation of water scarcity sensitivities to secular climatic variation: theoretical insights from a computational maquette

ABSTRACT

Increased demand associated with population or economic growth, and decreased supply under some climatic shifts, obviously contribute to water scarcity. As a fresh perspective, we offer a generic theoretical treatment using a computational “maquette”, employing parameterizations to avoid assumptions about the origin and scale of climate and demand changes. The results suggest a distinct (and more subtle) point: the sensitivities of water stress to changes in both the mean and the variance of hydroclimate are modulated by demand level. Theoretical behaviours generated by the reduced-complexity model are surprisingly intricate, including profound nonlinearities and bifurcations. These may form a lower bound on the dynamical complexity of the demand–supply–scarcity nexus. Overall, the outcomes suggest that demand growth substantially intensifies and nonlinearizes water stress sensitivities to secular climate variation, and, in particular, that the interactions between demand changes and second-order hydroclimatic non-stationarity may produce non-intuitive water scarcity impacts requiring much closer study.

EDITOR A. Castellarin; ASSOCIATE EDITOR N. Ilich     

长春市各级交通路线对城市功能用地变化的作用效应关系研究

利用长春市中心城区2003年、2013年土地利用现状图,运用廊道效应原理与ArcGIS空间分析功能,揭示了交通系统“快速化”背景下长春市各级交通路线对城市功能用地演替的作用效应关系。研究发现：轻轨、主干路、快速路对商服用地的吸聚效应依次增强,快速路沿线商服用地主要用于专业化市场建设,轻轨沿线商服用地用作综合性商场开发;快速路对沿线居住用地吸聚强度大于主干路,轻轨对沿线居住用地具有近距离排斥效应;在市中心区,快速路、主干路、轻轨对工业用地的排斥强度依次增强,但随着由中心至外围的过渡,快速路的排斥效应将转化为吸聚效应。各级交通路线对沿线城市功能用地作用效应的差异性,一定程度上推动了长春市城市地域结构的演变。     

Galaxy evolution in clusters

The galaxy populations in present-day clusters are distinctly different from those of the field, indicating that environment plays a strong role in galaxy evolution. This review discusses some of the recent observations of moderate to high redshift clusters. A consistent picture of galaxy evolution in clusters appears to be emerging, which includes a population of galaxies which formed early in the cluster history, as well as field galaxies which have had their star formation truncated upon falling into the cluster potential. Galaxy interactions probably play an important role in exhausting star formation in some of these galaxies. However, there is significant variation in the populations of different cluster samples, with substantial evidence that some galaxies have their star formation terminated more gradually. This suggests that different mechanisms may dominate in different clusters, perhaps because of the recent merging history of the clusters. We also present a recent analysis of population gradients in clusters which suggests that the observed evolution in cluster populations is consistent with a scenario where changing infall rates drive the fraction of star forming galaxies in clusters, rather than a changing physical mechanism within the cluster. Thus, galaxy populations may provide a fundamental measure of the growth of large scale structure. This revised version was published online in July 2006 with corrections to the Cover Date.