Pico- and Nanophytoplankton Dynamics in Two Coupled but Contrasting Coastal Bays in the NW Mediterranean Sea (France)

Due to its ecological context, the Toulon bay represents a site of scientific interest to study temporal plankton distribution, particularly pico- and nanophytoplankton dynamics. A monthly monitoring was performed during a two-year cycle (October 2013–December 2015) at two coupled sampling sites, referred to as Little and Large bays, which had different morphometric characteristics and human pressures. Flow cytometry analyses highlighted the fact that pico- and nanophytoplankton were more abundant in the eutrophic Little bay. Furthermore, it evidenced two community structures across the Toulon bays: at times, a co-dominance of picoeukaryotes, nanoeukaryotes, Synechococcus 1-like cells and Prochlorococcus-like cells was found, and at other times, a Synechococcus 1-like dominated community existed. The alternation of one structure or the other can be explained by a combined action of temperature regime, nutrient conditions and degree of contamination. This study showed that pico- and nanophytoplankton dynamics were mainly driven by temperature in both sites, as in other temperate Mediterranean regions. Thus, the community was mainly composed of picoeukaryotes and Prochlorococcus-like cells in the winter (<?15 °C), while it was dominated by Synechococcus 1-like cells in the summer (>?20 °C). Additionally, the multiple human stressors in the Little bay seemed to affect the increase in abundance of Synechococcus 1-like cells as they were preferentially observed in the Large bay.     

基于生态足迹的中国四大沙地地区可持续评价

基于社会经济统计数据,采用生产性生态足迹模型,评估并对比了我国四大沙地地区2000年和2015年的生产性生态足迹和生态赤字/盈余状态,以揭示区域的可持续性。结果表明：2000-2015年,四大沙地地区人均生态足迹总体呈现增加趋势,毛乌素沙地地区人均生态足迹年均增长率最高,达20.85%,增长量为79.21 hm²·人^-1;人均生态足迹主要以化石能源足迹和草地足迹为主;2000-2015年四大沙地地区生态赤字程度在不断增强,毛乌素沙地地区人均生态赤字变化量最大,达79.51 hm²·人^-1,造成赤字程度加大的主要原因是地区化石能源的大量生产。随着人们生活水平的提高,人们对资源的需求量也在不断增加,当前四大沙地地区社会经济的发展在一定程度上仍以自然资源大量生产和消耗为代价,经济发展和环境保护之间的平衡仍存在挑战,需要根据各地区的具体情况制定有针对性的管理措施,以维持区域的可持续发展。     

断裂应力特征及其转折控油气规律研究——以南堡凹陷为例

为了分析断裂对油气宏观分布规律的控制作用,寻找有勘探潜力的油气富集带,文中以地质力学理论为指导,对南堡凹陷断裂组合应力特征、断裂转折及成因进行解析,并结合砂体分布和古今构造应力场分布特征,对南堡凹陷东营组油气分布规律和有利勘探区带做了研究。结果表明:断裂转折部位对油气分布有着控制作用,东营组已探明的油气主要在帚状断裂系、入字形断裂系、交织式断裂系转折轴部高曲率附近呈环带状分布;断裂转折凹面一侧控油性明显,从宏观上来看,油气具有沿沉积相带由细到粗的构造脊高点以及弧形断裂转折凹面一侧的选择性运移的特征,断裂转折轴部高曲率高孔、高渗域与高孔、高渗砂体沉积相带的有利对置决定了油气的主流向;综合研究指出,南堡凹陷北堡构造带是今后优势勘探的首要区带,其次是南堡构造带和南堡4号蛤坨构造带南部。     

Laboratory sulfurisation of the marine microalga Nannochloropsis salina

To understand more fully the mode of preservation of organic matter in marine sediments, laboratory sulfurisation of intact cells of the cultured microalga Nannochloropsis salina was performed using inorganic polysulfides in seawater at 50°C. Solvent extractable and non-extractable materials were analysed by GC–MS and Py–GC–MS, respectively, to study the incorporation of sulfur into the microalgal organic matter. No GC-amenable sulfur-containing compounds were found in the extracts apart from some minor thiophenes with a phytanyl carbon skeleton. The residue after extraction and hydrolysis contained abundant macromolecular sulfur-containing moieties as revealed by the presence of dominant C₂₈–C₃₂ thiols, thiophenes, thianes and thiolanes in the flash pyrolysates. These products are thought to be formed from moieties derived from sulfurisation of C₂₈–C₃₂ diols and alkenols, characteristic lipids of N. salina. C₁–C₂ alkylated thiophenes were also found in the pyrolysates and probably result from moieties formed upon sulfurisation of carbohydrates. The highly resistant biomacromolecule (algaenan) synthesised by N. salina remains unaffected by sulfurisation. The non-hydrolysable residue isolated from the sulfurised N. salina thus comprises algaenan and (poly)sulfide-bound long alkyl chains. The sulfurisation experiments show that both selective preservation of algaenans and lipid and carbohydrate “vulcanisation” can be involved in the preservation of algal organic matter in marine environments.     

广东省1960～2007年降雨侵蚀力变化趋势分析

降雨侵蚀力反映由降雨引起的土壤侵蚀的潜在能力.本文利用广东省25个站点48年(1960～2007)的日雨量资料计算了各站的降雨侵蚀力,并用Mann-Kendall(M-K)非参数检验和克里格空间插值法分析了降雨侵蚀力的时空变化规律.结果表明:广东省降雨侵蚀力的空间分布呈沿海向内陆逐渐递减的趋势.全省大部分地区的年降雨侵蚀力呈现不明显上升趋势,且存在较明显的年代际和年际变化.降雨侵蚀力的年内分布特征和降雨量分布类似,呈"双峰型",主要集中在4～9月的雨季.对于季节序列,冬季、春季和夏季大部分地区的降雨侵蚀力有不同程度的上升,秋季全省几乎所有地区呈下降趋势.汛期的降雨侵蚀力变化特征与年降雨侵蚀力相似.     

地震诱发黄土滑坡稳定性评价中的不平衡推力法

以不平衡推力法为基础,同时考虑不同烈度、不同地震力作用方向条件下黄土滑坡的稳定性评价,以宁夏西吉回回川滑坡为例,进行了滑坡稳定系数 K 与地震系数 KS,与地震作用角度β的关系及滑坡稳定性敏感性分析.结果表明地震最危险作用方向与水平方向有一定夹角倾向坡外,且随地震系数增大而增大.黄土滑坡稳定性评价中应该考虑地震最危险作用方向.     

一种高精度的干涉雷达复数影像配准方法

在总结现有算法的基础上,提出了基于相干系数、Harris特征点、小波金字塔及TIN三角微分纠正技术的单视复数雷达图像的配准流程。通过ERS 1/2的实验表明,提高了配准的精度和效率,特别是保证了在没有精确轨道甚至没有轨道参数的情况下也能获得很高的配准精度,计算正确的干涉相位图。在重采样过程中采用的三角联网策略,进一步使匹配点的局部拟合误差得到有效控制,得到配准精度更高的复图像对。在CPU 3.06GHz计算机上,43 s内完成5000像素×1000像素的主辅图像的配准,平均相干系数为0.719855。     

Integrated Geological–Geophysical and Oceanographic Research in the South China Sea: Cruise 88 of the R/V “Akademik M.A. Lavrentyev”

Oceanology - Abstract—The paper gives brief results of comprehensive studies in the South China Sea obtained from a joint Russian–Vietnamese expedition in November 2019 (cruise 88 of...     

Aridity changes in the Temperate-Mediterranean transition of the Andes since ad 1346 reconstructed from tree-rings

The Andes Cordillera acts as regional ??Water Towers?? for several countries and encompasses a wide range of ecosystems and climates. Several hydroclimatic changes have been described for portions of the Andes during recent years, including glacier retreat, negative precipitation trends, an elevation rise in the 0° isotherm, and changes in regional streamflow regimes. The Temperate-Mediterranean transition (TMT) zone of the Andes (35.5°?C39.5°S) is particularly at risk to climate change because it is a biodiversity hotspot with heavy human population pressure on water resources. In this paper we utilize a new tree-ring network of Austrocedrus chilensis to reconstruct past variations in regional moisture in the TMT of the Andes by means of the Palmer Drought Severity Index (PDSI). The reconstruction covers the past 657?years and captures interannual to decadal scales of variability in late spring?Cearly summer PDSI. These changes are related to the north?Csouth oscillations in moisture conditions between the Mediterranean and Temperate climates of the Andes as a consequence of the latitudinal position of the storm tracks forced by large-scale circulation modes. Kernel estimation of occurrence rates reveals an unprecedented increment of severe and extreme drought events during the last century in the context of the previous six centuries. Moisture conditions in our study region are linked to tropical and high-latitude ocean-atmospheric forcing, with PDSI positively related to Ni?o-3.4 SST during spring and strongly negatively correlated with the Antarctic Oscillation (AAO) during summer. Geopotential anomaly maps at 500-hPa show that extreme dry years are tightly associated with negative height anomalies in the Ross?CAmundsen Seas, in concordance with the strong negative relationship between PDSI and AAO. The twentieth century increase in extreme drought events in the TMT may not be related to ENSO but to the positive AAO trend during late-spring and summer resulting from a gradual poleward shift of the mid-latitude storm tracks. This first PDSI reconstruction for South America demonstrates the highly significant hindcast skill of A. chilensis as an aridity proxy.     

居住区典型地物热环境的日变化及其相互影响分析

居住区热环境状况是影响局地微气候变化的重要因素,研究居住区地物的热环境特征,对于了解和改善微气候具有重要意义。为了更好地揭示居住区热环境特征,本研究使用热红外成像仪对北京市某校园居住区进行观测,获取了夏季不同天气状况下（晴天、阴天、多云）的24 h热红外影像数据。依据各天气数据和地物属性,系统分析了各地物日变化规律,并通过垂线法判定邻近地物的温度边界范围,进而揭示出地物间温度交互特征。结果如下：① 太阳辐射是影响地物白天温度变化的主要因素,与地物温度呈正相关性;在多云天气下,地物的最高温度滞后至16:00出现,且地物温度曲线呈现连续的“锯齿状”升降趋势,云层的大量运动是导致多云天气下的地物温度波动变化的关键因素;沥青道路在夜间的温度均高于其他地物,并且夜间持续放热,提生周围环境温度;阴影能够有效减少地物吸收的太阳辐射量,降低地物表面温度;植被的冠层厚度与地物温度呈负相关性,因此增加居住区内绿植的冠层厚度,增大区域阴影面积有助于改善局地微气候;② 树木和裸土在06:00和14:00的温度交互作用强烈,表明在地物交界处,全天持续发生显著的热量交换;而夜间至凌晨,草坪与人行道持续进行热量交换,帮助降低路面温度,缓解周围高温状况。