Spatial distribution of pico-and nano-phytoplankton and bacteria in the Chukchi Sea in relation to water masses

We evaluated the relationships between water masses and pico- and nano-phytoplankton and bacterial abundance in the Chukchi Sea. The abundance of picoplankton ranged from 0.01 ~ 103 cells.mL1 （100 m, station R05） to 2.21 x 103 cells.mL-1 （10 m, station R05） and that of nanoplankton ranged from 0.03 x 103 cells.mL-I （100 m, station R07） to 2.21 ~ 104 cells.mLq （10 m, station R05）. The lowest abundance of bacteria in the whole water column （0.21 x 106 cells.mLq） was at 100 m at station R17, and the highest （9.61 x 106 cells.mLL） was at 10 m at station R09. Melting sea ice affected the physical characteristics of the Chukchi Sea by reducing salinity of the surface mixed layer, resulting in greater hydrodynamic stability of the water column. These changes were accompanied by increased bacterial abundance. The warm Pacific water brought nutrients into the Chukchi Sea, resulting in greater abundance of bacteria and nano-phytoplankton in the Chukchi Sea than in other regions of the Arctic Ocean. However, the abundance of pico-phytoplankton, which was related to chlorophyll a concentration, was higher in Anadyr water than in the other two water masses. The structures ofpico- and nanoplankton communities coupled with the water masses in the Chuk- chi Sea can serve as indicators of the inflow of warm Pacific water into the Chukchi Sea.     

河北省坝上地区1971-2010年沙尘暴日数变化特征及与气象因素关系

利用1971-2010年地面气象观测资料,分析了坝上地区沙尘暴日数的季节变化和年变化特征及其与大风、降水、气温的关系。结果表明：坝上地区沙尘暴日数具有明显的季节性变化特征,春季沙尘暴日数最多,占全年沙尘暴日数的84.88%,秋季最少,仅占全年沙尘暴日数的1.39%,冬季沙尘暴日数多于夏季;从年变化特征上看,20世纪70年代沙尘暴发生日数最多,80年代减少,90年代达到最少,2000年后沙尘暴日数又开始增加,但总体来说沙尘暴日数呈现出波动中下降的趋势;年沙尘暴日数和年大风日数有显著的正相关,与前期、同期降水量没有达到显著相关,但是有着很好的对应关系,与年平均气温有显著的负相关。     

生命起源、早期演化阶段与海洋环境演变

近年的研究表明,地球生命可能起源于距今39~36亿年之间。除了碳元素以外,水、氮、氢、磷等元素也是生命起源的必备条件,黏土矿物和金属硫化物是有机质合成的重要催化剂,有热液活动的碱性热水环境是最有利生命发生的孵化场。自原核生物在约3.5 Ga出现之后,生命就一直表现为与环境的协同进化关系。大气圈氧化是地球史上最重大的地质事件之一,它不仅改变了地球表层环境条件、加速了表生地质过程和新矿物的产生,而且改变了海洋化学条件和元素循环。大气圈氧化事件的根本在于产氧蓝细菌的出现,元古宙中期海洋化学性质的整体转换也与微生物过程密切相关。新元古代多细胞生物的繁盛和末期后生动物的出现及其在寒武纪初期的快速多样化是生物圈演化的重大飞跃。这个过程也与海洋氧化增强及其导致的海洋化学变化密切相关,其中硫化水域消失和减弱以及海水中微营养元素可得性增加可能是重要因素,这也与微生物过程直接相关。     

1961-2010年青藏高原降水时空变化特征分析

利用青藏高原69个气象台站的降水量资料,采用旋转经验正交函数分析（REOF）、线性趋势分析和累积距平法,系统地研究了1961-2010年青藏高原降水的时空变化规律,揭示了青藏高原不同区域降水变化的差异性.研究表明：近50 a来青藏高原降水量总体呈现增加趋势,增长率为6.7 mm·（10a）^-1;青藏高原降水季节分配极不均匀,雨季和旱季非常明显,雨季降水占有主导作用;青藏高原降水由东南向西北递减,而且年际变化具有一定的多元化特征;青藏高原降水量变化空间分布差异显著,采用REOF法将整个高原划分为10个小区,每个小区降水变化都具有不同的特征,除了青海东北部区和青海东南部-川北区降水呈减少趋势外,其他8个小区降水均呈增加趋势.     

氮肥及秸秆有益于提高设施番茄土壤芽孢杆菌及假单胞菌的种群数量

Root zone N management can reduce N fertilizer input and avoid nitrate pollution in greenhouse tomato production; however, little information is available on how reduced N affects soil microbes, especially dominant bacteria populations in long-term continuous greenhouse systems. This study investigated the effects of different combinations of N and straw on the population size of soil total bacteria and two dominant bacteria (Pseudomonas spp. and Bacillus spp.), and microbial community structure in a 6-year greenhouse tomato trial. The treatments were basal fertilizer (10 t ha-1 chicken manure; control), conventional high N treatment [600 kg N ha-1], conventional high N treatment with wheat straw, reduced N treatment [300 kg N ha-1 less than conventional], and reduced N treatment with wheat straw. Six years of reduced mineral N fertilization did not lead to a decrease in fruit yield. Both mineral N fertilizer and straw increased the numbers of soil bacteria (Bacillus spp. and Pseudomonas spp.) compared with the control, but the numbers were not affected by the amount of mineral N fertilizer (high vs reduced). Different denaturing gradient gel electrophoresis patterns were evidence that soil bacterial communities were changed by N treatments and straw application, but little difference in bacterial diversity was detected between high N and reduced N treatments. These results indicated that a reduction in N fertilizer input was possible in greenhouse tomato production and was beneficial in sustainable agriculture.     

莱州湾南岸海水入侵特征及基于WA-NARX混合模型的动态预测

随着我国海岸带经济的快速发展与人类活动的加剧,地下水超采现象十分严峻,由此引发的海水入侵已成为滨海地区普遍存在的地质问题.本研究以莱州湾南岸海水入侵区为研究对象,根据地下水连续监测数据分析了地下水位和电导率的动态变化特征.在此基础上,基于降雨、蒸发、潮汐及农业排灌用电量等影响地下水动态变化的因素,建立了小波分析(WA)...     

无控制点数据的无人机影像快速处理

本文以四川地震灾区作为典型研究区,尝试在无其他控制点数据时,仅利用小型无人机影像和无人机系统自身记录的辅助数据,进行无人机影像的快速匹配、拼接和纠正处理。首先,对小型无人机获取的影像数据和辅助数据进行了详细分析,然后,将小区域原始影像利用影像匹配算法进行自动拼接,拼接后的分块区域再根据辅助数据进行纠正处理。SIFT算法被运用到无人机影像的匹配中,达到了较好的速度和精度;分块拼接后的成果利用辅助数据的伪中心点进行纠正,相对精度较高,镶嵌结果无视觉错位。最后,将纠正结果和GoogleEarth影像数据叠加进行精度检查,主要标志性地物重叠良好。     

New Views on Global Change

1 Global cooling brings about drought anddesertThe achievements of geoscience presented in the29th 30th and 31th IGC indicated that the earth willgo to a new glacial epoch in a long run but it will getwarmer and warmer in a short period because of thehuma…     

黄河三角洲飞雁滩海岸的侵蚀与机理

飞雁滩海域是1964—1976 年黄河刁口河流路入海区域。根据地形和断面水深监测资料,阐述了该岸段流路废弃后的岸滩侵蚀特征和地貌变化。研究结果表明,刁口河流路废弃后飞雁滩海岸向海凸出的地形特征,是造成该岸段强烈侵蚀的重要原因。进一步结合波、流动力的对应分析认为,波浪以掀沙为主,潮流以输沙为主,波浪和潮流的联合作用是飞雁滩海岸侵蚀的主要动力机制,其中潮流主要通过余流携沙外输,造成近岸泥沙亏损。     

聚焦波作用下半浸没圆柱所受波浪载荷理论研究

由于畸形波的物理机制较复杂,有关畸形波-结构物相互作用的理论研究进展缓慢。然而对于较简单的畸形波模型与规则结构体,可以给出畸形波-结构物相互作用的理论解。本文基于畸形波的一种基本模型聚焦模型,采用解析方法研究其对半浸没圆柱体产生的波浪载荷。为保留畸形波的大部分特征,聚焦模型采用高斯包络描述。通过流场分隔给出绕射势,进而给出圆柱所受水平波浪力与波浪弯矩。采用适当方法简化理论公式,并与数值结果进行对比验证。此外,系统分析了聚焦程度、浸没深度与聚焦位置等参数对波浪载荷的影响。