岬湾海滩剖面中长期变化特征及其控制因素——以青岛石老人海滩为例

了解海滩剖面变化可以更好地理解海滩动态过程。利用2007年5月~2014年12月近8 a青岛石老人海滩剖面的实测资料,计算剖面各段单宽体积变化量及后滨宽度,结合交叉小波和小波相干分析方法,探讨海滩剖面中长期淤蚀变化特征及其控制因素。结果表明,近8 a来海滩剖面表现为侵蚀状态,不同岸段侵蚀程度不同。剖面1岸段侵蚀明显,剖面2和剖面3岸段轻微侵蚀。剖面的变化过程可划分为平稳期、剧变期和微调期3个时期。各时期剖面的季节性变化较复杂,平稳期具冬蚀夏淤的交替变化特征,整体淤蚀量较小;剧变期剖面呈阶段性蚀退,变化幅度相对较大,微调期剖面可能仍处于剧变期的恢复阶段,季节性变化不明显。剧变期和微调期的小波交叉谱和相干谱分析显示,波浪和前滨单宽体积相干性较好,尤其当大于2 m的波高达到10%以上,海滩地形可以和波高变化产生同周期的变化。因此波高变化基本控制了剖面的季节变化。而海滩长周期变化主要受控于风暴潮作用及其漫长的恢复期,沿岸输沙和海平面变化则一定程度上导致了剖面长期侵蚀格局的形成。     

Tracking temporal palynofloral changes close to Cretaceous-Paleogene boundary in Deccan volcanic associated sediments of eastern part of central Deccan volcanic province

Deccan volcanic sequences( DVS) in the central Deccan volcanic province( CDVP) are designated as Sahyadri Group having ~ 500 m thick lava pile associated with multiple sedimentary beds at different stratigraphic levels. In the eastern part of CDVP between the latitude 19 °55 '--20 °25 ' N and the longitudes 78 °15 '--78 °30 ' E,palynological investigation of the intertrappean sedimentary beds at five stratigraphic levels was carried out. The study was basically aimed for tracking the floral and environmental changes across the Deccan transition. The resulting finds indicate that the intertrappean sediments at the lowest stratigraphic level between the earliest lava flows are characterized by presence of marker Maastrichtian palynomorphs- Gabonisporis vigourouxii,Aquilapollenites bengalensis,Azolla cretacea and Farabeipollis associated with triporate and tricolpate pollen grains,phytoliths of Oryzeae of Poaceae family and peridinoid dinoflagellate cysts. The increasing volcanism deteriorated the existing flora as evident by absence of pollen-spores and presence of only structured biodegraded organic matter,fungal spores,acritarchs and algal( Botryococcus) remains in the sediments of higher-up in the sequence. For chronostratigraphic constraints on the lava flows magnetic polarity of the flows bracketing the intertrappean beds was investigated. The results indicated presence of N-R-N-R magnetic polarity in the basal lava pile that are interpreted as representing the magnetochron C30 N to C28 R( Maastrichtian-Paleogene). The floral change begins with the onset of volcanism in the chron C30 N and floral deterioration is observed in C29 N with increasing volcanism and it is only in the chron C28 R( Danian) that some evidence of recovery of flora is recorded. The current study shows that in eastern part of CDVP the post Cretaceous-Paleogene boundary eruptions represent the main phase of eruptions that triggered deterioration of the flora.     

Impacts of climate change on the hydrological cycle over France and associated uncertainties

This study deals with the evolution of the hydrological cycle over France during the 21st century. A large multi-member, multi-scenario, and multi-model ensemble of climate projections is downscaled with a new statistical method to drive a physically-based hydrological model with recent improvements. For a business-as-usual scenario, annual precipitation changes generally remain small, except over southern France, where decreases close to 20% are projected. Annual streamflows roughly decrease by 10% (±20%) on the Seine, by 20% (±20%) on the Loire, by 20% (±15%) on the Rhone and by 40% (±15%) on the Garonne. Attenuation measures, as implied by the other scenarios analyzed, lead to less severe changes. However, even with a scenario generally compatible with a limitation of global warming to two degrees, some notable impacts may still occur, with for example a decrease in summer river flows close to 25% for the Garonne.     

Spatiotemporal change patterns of urban lakes in China’s major cities between 1990 and 2015

China has experienced unprecedented urbanization in the past decades, resulting in dramatic changes in the physical, limnological, and hydrological characteristics of lakes in urban landscapes. However, the spatiotemporal dynamics in distribution and abundance of urban lakes in China remain poorly understood. Here, we characterized the spatiotemporal change patterns of urban lakes in China’s major cities between 1990 and 2015 using remote-sensing data and landscape metrics. The results showed that the urban lake landscape patterns have experienced drastic changes over the past 25 years. The total surface area of the urban lakes has decreased by 17,620.02?ha, a decrease of 24.22%, with a significant increase in the landscape fragmentation and a reduction in shape complexity. We defined three lake-shrinkage types and found that vanishment was the most common lake-shrinkage pattern, followed by edge-shrinkage and tunneling in terms of lake area. Moreover, we also found that urban sprawl was the dominant driver of the lake shrinkage, accounting for 67.89% of the total area loss, and the transition from lakes to cropland was also an important factor (19.86%). This study has potential for providing critical baseline information for government decision-making in lake resources management and urban landscape design.     

Chronology of the Mediterranean sea-level highstand during the Last Interglacial: a critical review of the U/Th-dated deposits

Relative sea-level (RSL) evolution during Marine Isotopic Stage (MIS) 5 in the Mediterranean basin is still not fully understood despite a plethora of morphological, stratigraphic and geochronological studies carried out on highstand deposits of this area. In this review we assembled a database of 323 U/Th-dated samples (e.g. corals, molluscs, speleothems) which were used to chronologically constrain RSL evolution within MIS 5. The application of strict geochemical criteria to the U/Th samples indicates that only ~33% of data available for the Mediterranean Sea can be considered ‘reliable’. Most of these data (~65%) refer to the MIS 5e highstand, while only ~17% could be related to the MIS 5a. No attribution to MIS 5c can be unequivocally supported. Nevertheless, the resulting framework does not allow us to define a satisfactory RSL trend during the MIS 5e highstand and subsequent MIS 5 substages. Overall, the proposed selection of reliable/unreliable data would be useful for detecting areas where MIS 5 substage attributions are not supported by confident U/Th chronological data and thus the related reconstructions need to be revised. In this regard, the resulting framework calls for a reappraisal and re-examination of the Mediterranean records with advanced geochronological methodologies.     

人类从哪里来？——（4）人类演化与古地理、古环境和古气候变化

详细介绍了8 Ma以来全球气候变化的规律,研究表明地球上主要发生过3次冷气候事件：第一次冷气候事件大约发生在距今7 Ma,一股强烈的干冷气流刮过欧洲大陆,穿越赤道地区直达非洲大陆,使得原始森林开始萎缩,面积的缩小导致古猿与人类发生演化分异;第二次冷气候事件大约发生在距今4.2 Ma,那时干冷气候持续发展,非洲大陆的原始森林进一步萎缩,并逐渐演化为稀树草原,出现了南方猿人和傍人;第三次冷气候事件大约发生在距今2.3 Ma,全球气候变化波动较大,冷-暖气候交替发育,地球上出现了真正意义上的人（人属）,并逐渐演化成现代人。根据目前的研究,人类的起源和演化与古地理、古环境和古气候变化密切相关,人类演化历史大致可分为7个时期：撒海尔猿人—原初猿人时期、地居猿人时期、南方猿人—傍人时期、能人—鲁道夫人时期、匠人—直立人时期、先驱人—海德堡人时期和智人时期。     

三江源区大气可降水量时空特征及其与降水关系

利用1979—2016年欧洲中期天气预报中心(ECMWF) ERA-Interim (1°×1°)再分析资料中的经、纬向水汽通量和大气可降水量(precipitation water vapor,PWV)数据,采用相关性分析、趋势分析法、累积距平、IDW等方法,分析三江源地区PWV与水汽通量的时空分布特征、降水转化率(precipitati-on conversion efficiency,PCE)变化规律。结果表明:过去的38 a,经、纬向多年平均水汽通量分别为50. 2、196. 7 kg·m-1·s^(-1),纬向水汽通量气候倾向率比经向大。南边界为纬向主要水汽输入边界,东边界为经向主要水汽输出边界,纬向水汽输送大于经向输送。多年平均PWV为1998. 3 mm,近38 aPWV呈现微弱增加趋势,1979—1997年,PWV呈下降趋势,1998年后PWV呈增加趋势,同期降水也在增加,说明该时段三江源地区气候转湿。PWV与水汽通量的年际变化趋势和转折年相一致。三江源区多年平均PCE为24. 57%,1989年PCE最高,达32. 76%,各季节平均PCE空间分布与年平均PCE分布一致,均表现出南部、东南部高,西部、东北部低的变化特征,各季节PCE大小差异明显,春季多年平均PCE为15. 92%,夏季25. 67%,秋季21. 01%,冬季仅7. 03%。     

Trends in stream and river temperature

Information on past and likely future trends in water temperature from different parts of the world is collated. The potential causes of trends in the thermal regimes of streams and rivers are many, but the existing database of water temperature information is inadequate to provide a global perspective on changes during the recent, let alone the more remote, past. Data from Europe suggest that warming of up to ca. 1°C in mean river temperatures has occurred during the 20th century, but that this trend has not been continuous, is distorted by extreme hydrological events, is not correlated with simple hydrometeorological factors and has been influenced by a variety of human activities. Predictive studies indicate that an accelerated rise in stream and river temperatures will occur during the next century as a consequence of global warming. However, forecasts must be tentative because future climatic conditions are uncertain and interactions between climate, hydrological and vegetation changes are complex.     

区域农业用地营养盐剩余量的长期变化研究

根据太湖南部长兴县农业统计资料,对该地区1949~2002年农业用地上N、P的剩余量作出评估。评估结果认为,1949~2002年期间,单位农业用地面积的N、P剩余量具有显著地增加趋势。20世纪50及60年代期间,N的剩余量增加缓慢,自70年代中期以后增加迅速。1996年达到历史最大值。1996年后,N剩余量呈现减少趋势。60年代初期以前,P处于亏损状态。1975~1980年期间,P剩余量呈现缓慢增长趋势,其后出现回落,自80年代中期以后出现迅速增加趋势。1992~1998年期间,P剩余量维持在35~45 kg/(hm²·a)之间的高水平变化,自1999年以后出现显著回落。     

Observation on height changes of chinese tide gauges by GPS

IntroductionBecause of global temperature rising and glacierthawing,the sea level has risen about 10-25 cmin the past century[1]. The sea level change isone of the main ai ms in global change monito-ring. Presently the basic tool used in sea levelmonitori…