鄱阳湖沉积物可转化态氮分布特征及其对江湖关系变化的响应

选取不同高程鄱阳湖表层沉积物,通过研究其总可转化态氮与各形态可转化态氮含量及分布特征,试图揭示江湖关系变化导致的水位变化对鄱阳湖沉积物氮潜在释放风险的影响.结果表明:1鄱阳湖表层沉积物总氮(TN)含量在389~3 865 mg·kg-1之间,空间分布上呈"五河"入湖尾闾区湖心区北部湖区的趋势;总可交换态氮含量在319.36~904.56 mg·kg-1之间,占TN的52%,空间分布趋势与TN相同;2鄱阳湖3个湖区沉积物各形态可转化态氮的含量大小排列次序均为:SOEF-N(强氧化剂可提取态氮)≈SAEF-N(强碱可提取态氮)WAEF-N(弱酸可提取态氮)IEF-N(离子交换态氮);3江湖关系变化致使鄱阳湖枯水期沉积物出露时间提前并且延长,进而导致不同高程沉积物可转化态氮(TTN)含量差异明显,3个湖区沉积物可转化态氮含量均表现为枯水期丰水期,高程越高,由于其沉积物出露时间较长,可转化态氮含量较高,即可转化态氮含量12 m~13 m高程沉积物11 m~12 m高程沉积物10m~11 m高程沉积物;4随着高程的增加,沉积物各形态可转化态氮含量都呈现增加的趋势,其中SAEF-N和WAEFN含量及其占总可转化态氮的比例变化幅度较小,而IEF-N和SOEF-N含量以及其占总可转化态氮比例的增幅均较为显著.如果江湖关系进一步变化,枯水期水位继续下降,势必会引起沉积物出露面积增大及出露时间延长,从而导致沉积物TN、可转化态氮以及释放风险较高的氮形态IEF-N和SOEF-N含量的增大,来年丰水期可能会增加鄱阳湖沉积物氮释放风险.     

武汉汉江水源地水质变化趋势及风险分析

武汉汉江水源地是全国重要饮用水水源地之一,其水质好坏关系到武汉市数百万居民生活及生产用水安全.在引汉济渭、南水北调中线和鄂北调水等大型水利工程建设运行背景下,利用2004～2021年水质监测成果,对武汉市汉江水源地水质变化趋势及风险进行研究.结果表明,武汉汉江水源地水体中总磷、高锰酸盐指数和氨氮等污染物浓度与武汉市城市集中式地表水饮用水水源保护区管理要求存在一定差异,尤其是总磷存在较大超标风险.水源地水体中藻类生长基本不受氮、磷和硅浓度限制,若不考虑其他因素,水温适宜时(6～12℃)暴发硅藻“水华”的风险较高;来水水质对水源地影响较大,西湖水厂至宗关水厂取水口间可能存在污染物汇入;高锰酸盐指数、总氮、总磷和氨氮等水质参数浓度时空变化趋势不一致,尤其是氮、磷元素,2016年以来其比值呈快速上升趋势,水体N/P的显著变化可能会引起浮游藻类种群结构及数量改变,从而影响供水安全.水源地水体总体处于中营养至轻度富营养状态,极个别时段可能会出现中度富营养的状况,当前水体营养状态有好转趋势.有必要对水源地污染物来源、数量和变化趋势深入调查以化解潜在供水风险.     

历史时期长江中游水灾与厄尔尼诺事件的遥相关

长江中游历来是长江流域水灾最严重的地区，研究历史时期这一地区水灾发生的变化波动并找出其与厄尔尼诺事件的遥相关，将有助于对长江中游水灾发生的预测。对这二个时间序列自1525年以来的数据进行了统计学分析。结果表明，水灾发生的主要周期比厄尔尼诺事件发生的周期要长：后者主要表现为2年和3~4年的振动，而前者的主要周期为2年、8年和40年，其显著性也没有后者明显（但都超过了0.03的置信度）。通过进一步分析历史时期长江中游水灾与厄尔尼诺事件的耦合振动，发现它们之间存在显著的遥相关。结果表明，长江中游水灾对厄尔尼诺现象的响应不仅存在着如许多中国学者相信的短期滞后（如：1年），而且还存在着比较长时间的滞后（最长可达8年）。研究结果同时表明，如果厄尔尼诺事件发生的相距时间愈短，这一时期长江中游水灾响应的滞后时间也愈短，反之亦然。     

Marine Ecological Research in New Zealand: Developing Predictive Models through the Study of No-Take Marine Reserves

Abstract:  New Zealand established its first no-take marine reserve more than 25 years ago. Twenty no-take marine reserves have now been created, although few of these are considered comparable. We considered whether existing conceptual models of population and community structure based only on data from exploited systems lack the baseline information of natural states necessary to make accurate predictions for new reserves. Three of the oldest and best-studied reserves are situated on the northeastern coast of New Zealand. These reserves are considered broadly comparable replicates, and research has shown the recovery of previously exploited predator populations and the reestablishment of trophic controls over community structure and productivity. None of the major changes was predicted when the reserves were created. All the observations from and experimental tests of hypotheses in these three ecologically comparable reserves have provided predictive models for future reserves. Recent surveys in newly created reserves, however, suggest that these models are bioregion and habitat specific. In these new reserves the recovery of previously exploited predators was predicted but did not always occur. Where trends were correctly predicted, the speed and amplitude of the changes were not accurately predicted. Research in New Zealand suggests that it is not yet possible to predict explicit outcomes for newly created reserves and less possible to predict detailed results for systems of reserves. Results from a representative system of reserves, including all major habitats within all bioregions and broadly comparable reserves, are needed. Such a system will enable the range and variety of natural ecosystem dynamics to be investigated and provide the controls necessary to measure the effects of exploitation.     

上海市人口分布变动的空间特征分析

空间自相关分析是一种空间统计的方法。可以揭示区域变量的空间结构形态。通过对2000-2003年期间上海市乡镇人口密度变化率的空间相关性分析，发现上海市近几年人口分布空间变动格局表现为以中心城区为中心的环状分布模式，中心城区和远郊区人口密度变化小。人口增长缓慢，而近郊区人口密度变化大，人口增长迅速。全市人口密度变化率存在着显著的空间集聚现象。四种类型的空间关联在空间分布上具有明显的规律性。研究结果表明，目前上海市人口郊区化趋势明显。高人口密度区域在不断向外扩张，人口分布与经济、交通等社会发展因素的关系日益密切。这些研究结果说明利用空间自相关统计方法能够扩展和加强对人口分布空间模式的研究．从而为经济总体布局和城市化建设提供辅助参考作用。     

Adaptation or conflict? Responses to climate change in water management in Bangladesh

The potential of climate change to impact local conflict and cooperation over natural resources has received relatively little attention. Bangladesh floodplains are highly vulnerable to environmental stresses that are worsening with climate change, and community organisations have to respond to water insecurity − seasonally too little or too much. Two case studies based on action research in contrasting water and climate stressed floodplain environments in Bangladesh investigate local conflicts over water management that worsened when water regimes changed. By overcoming conflicts and improving adaptation for all local actors the cases reveal the importance of local knowledge, innovations in institutions, external facilitation, and incentives provided by disadvantaged groups who contribute towards costs in return for a share in decision making power and better adapted water management. The cases show how community organisations diversified their responsibilities and took up the challenge of water management to address local priorities and overcome conflicts. Without a more flexible and enabling approach, public investments in adaptation are likely to focus on strengthening existing water management infrastructure without understanding local social interactions and complexity. This may strengthen elite dominance and local conflicts if there is no comparable investment in developing robust and fair local institutions.     

Why the IPCC should evolve in response to the UNFCCC bottom-up strategy adopted in Paris? An opinion from the French Association for Disaster Risk Reduction

The levels of greenhouse gases in the atmosphere keep increasing every year, and despite the adoption of the Paris agreement, one cannot expect any significant dip in the trend in the near future. We may therefore legitimately question the efficiency of the current governance system, notably concerning the interplay between science and policy. The strategy adopted by the UNFCCC in Paris contrasts with the strategy adopted in Kyoto, as it endorses a dynamic that is more bottom-up. Its success will depend greatly on the ability of the actors to mobilise on climate issues and to find ways to work together. Scientific expertise has a key role to play to this respect. This paper is a reflection led by the French Association for Disaster Risk Reduction on how the Intergovernmental Panel on Climate Change could evolve in order to usefully accompany that strategy. Introducing more reflexivity in the assessment process and widening aspects of the expertise to a more diverse and transdisciplinary range of actors could improve the treatment of uncertainties, multi-scale interactions and the appropriation of expertise, as well as the integration of adaptation and mitigation policies. In practical terms, this could involve more working groups, which could become more focused, drawing up shorter but more frequent reports, and taking account of the “grey” expert literature. The implementation of such an approach merits further investigation, because these improvements could help address the governance challenges in climate change.     

洞庭湖区近50年土地利用/覆盖的变化研究

利用1978，1989，1998年的Landsat卫星遥感影像资料及20世纪50年代航测的地形图，研究了洞庭湖区近50年土地利用／覆盖及其景观结构的变化，土地利用／覆盖类型分为水体，湿地，农田，林地和建成区五类，各时期遥感影像的总体分类精度都在80％以上，运用ArcInfo和ArcView GIS软件，将不同时期的土地利用／覆盖格局在空间上清晰地显示出来，通过叠加4个不同时期的影像分类图，计算出各种土地利用／覆盖类型转变为其他土地利用／覆盖类型的比例，洞庭湖区50年来水体面积不断减少，减少量为1460km^2，其中1955年到1978年水面面积缩小了970。57km^2，分别为1978年到1989年和1989年到1998年缩小面积的2．23倍和1805倍，湿地面积逐渐增加，1998年湿地面积分别为1955，1978和1989年的1．46，1．41和1．09倍，农田的面积百分比从1955年的54．70％增加到1978年62．15％，又逐渐降低到1989年的51．88％和1998年的48．17％，林地的面积1978年比1955年减少了17％,，1989年比1978年增加了57％，1998年比1989年增加了11％，建成区的变化表明近50年来湖区城市化的进程，洞庭湖区土地利用／覆盖及其景观结构的变化是社会经济和自然因素综合作用的结果。     

Seven Years of Change Following Liming of Sphagnum Communities in Sector Vii of the Loch Fleet Catchment

In 1986, application of lime within the upper wetland area of sector VII of the Loch Fleet catchment initiated numerous unscheduled small-scale experiments on the vegetation of this heterogeneous terrain. Vegetation changes and erosion were monitored in permanent or relocated plots established in 1987 and 1989 and re-surveyed in 1993, seven years after liming.

The most striking early effect, possibly occurring within a few weeks of lime application, was the death of Sphagnum papillosum carpet in soakways within the 2.5 ha area. Some patches of dead material were washed away, but bare surfaces were generally colonised by vascular plants, notably Juncus bulbosus. Effects in moorland and bog communities with dwarf shurbs were more subtle, involving reduction in Sphagnum cover and expansion of Erica teralix, Molinia caerulea, sedges and Narthecium ossifragum, but little change in the frequency of occurrence of Calluna vulgaris.     

Hydrologic and land use impacts on vegetation growth and NPP at the watershed scale in a semi-arid environment

Significant, adverse climatic change and drastically increased demographic pressure have strongly affected, in recent years, the hydrology and environment in the semi-arid Sahel region of West Africa. Marked rain deficits have coincided with increased water runoff, meaning less water availability for the vegetation. Conversely, changes in vegetation cover have had strong repercussions on the hydrologic cycle. To study these phenomena, the coupling of two explicit, process-based models, of catchment hydrology and of mixed vegetation cover, respectively, has been undertaken and applied to a 2 km² site in Niger. Some of the first significant results are presented herein. Some are consistent with intuitive judgments that can be made in the absence of a coupled model, others are much less so and show that representation through model coupling of hydrosphere/biosphere interactions is essential to produce more reliable analyses and projections. In particular, it is found that the relation of biomass productivity to rainfall under this dry, water-limited climate is not as straightforward as one would expect, more specifically, that its main control may not be the total season rainfall.