柳林泉域岩溶水特点与地质背景条件分析

柳林泉域作为我国北方典型的单斜 - 顺置式岩溶水资源系统 ,岩溶水在循环过程中表现出与其它泉域共性的同时 ,也存在一些非常奇特的特征: ( 1)由于泉域内断层、褶皱轴和区域隔水顶板的阻水作用 ,造成了岩溶地下水在主径流方向上的二级排泄与三次富集; ( 2)由于泉域中部王家会阻水性背斜轴的倾覆所形成的地下潜流断面梯形形态 ,导致了泉水流量衰减幅度与阻水断面上游区岩溶地下水位下降幅度的不匹配; ( 3)由于泉域南、北翼岩溶地下水循环路径和所处的地球化学背景不同 ,导致了分布在三川河两岸相距不足 300m 的泉水水化学特征表现出很大的差异性 ; ( 4)由于岩相建造地处中奥陶世古膏盐湖东部边缘 ,泉域西部中硬石膏溶解不仅形成了岩溶热水 ,而且还使得柳林泉成为“锶矿泉水”。 上述特征都是由柳林泉域特定的地质结构、地球化学环境和岩相古地理条件所决定的。      

宁夏春季降水及其典型年份水汽通量特征分析

选用1961—2006年宁夏19个主要站降水量分析宁夏春季降水的气候特征,得出其存在16 a左右的长周期和8 a左右的短周期,但年际、年代际变化特征不明显。宁夏春季降水量与春季首场透雨出现日期存在显著的负相关关系,春季如果出现首场透雨,其降水量对整个春季降水量贡献很大。研究春季降水典型旱涝年850—700 hPa水汽通量场的分布,发现影响宁夏春季降水的水汽有两支,一支是来自于孟加拉湾洋面上向东北方向输送的水汽,一支是从里海沿我国新疆地区向东输送的水汽,典型涝年这两支水汽带汇合区域明显向北抬,且汇合区域大,中心值大;典型旱年这两支水汽带汇合区偏西、偏小,中心值也较平均年减小。典型旱涝年水汽通量在u方向差别不大,但在v方向上呈反位向分布,典型涝年宁夏为正距平控制,典型旱年为负距平控制。     

Biological control of short-term variations in the concentration of DMSP and DMS during a Phaeocystis spring bloom

In the spring of 1995, short-term variations in the concentration of particulate and dissolved dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) were monitored in the western Wadden Sea, a shallow coastal region in open connection with the North Sea. Significant correlations were found between abundance of Phaeocystis globosa and particulate DMSP; concentrations increased rapidly from 100 to 1650 nM in the middle of April. Highest DMS concentrations were found during the initial phase of the exponential growth of the bloom. DMS production and loss rates of DMSP and DMS were estimated experimentally during various phases of the bloom. DMS production and consumption were roughly in balance, with production only slightly exceeding consumption at the start of the bloom. Rates of production and consumption were highest during the exponential growth phase of Phaeocystis and declined in the course of the bloom (from 300–375 to less than 5 nmol dm⁻³ d⁻¹). Demethylation of DMSP increased during the bloom (from 11 to 1300 nmol dm⁻³ d⁻¹); it accounted for up to 100% of the DMSP loss at the end of the bloom. The shift from DMSP cleavage to demethylation in the course of a Phaeocystis bloom implies that DMS concentrations are not necessarily highest at the peak or towards the end of blooms.     

Behavior of Cu, Ni and Cd during nutrient depletion in a spring bloom in Funka Bay

The concentrations of Cu, Ni and Cd were determined in Funka Bay during a spring phytoplankton bloom, consisting of diatoms. Just after the bloom, both dissolved Cd and nutrients were removed in the euphotic zone. However, the removal ratio of Cd to phosphate was very different from that in seawater. The removal of Cd took place at a Cd/phosphate ratio of 0.07×10⁻³, which was lower than in seawater before the bloom (0.25×10⁻³), leading to an increase in this ratio in seawater exceeding 0.7×10⁻³ at the end of the bloom. Elevated concentrations of Cd and phosphate were observed in the deeper layer after the bloom due to the decomposition of detrital materials produced in the bloom. The ratio of Cd/phosphate in the regeneration step was 0.24×10⁻³ which was different from the removal ratio of 0.07×10⁻³. These observations suggest that the high Cd/phosphate ratio in the regeneration would reflect a relatively high regeneration rate of Cd than that of phosphate. No significant decrease in Cu and Ni concentrations was observed during the development of the bloom, suggesting that biological removal of these metals was not so significant during the spring bloom. The concentrations of Cd, Cu and silicate in surface waters increased after the bloom with decreasing salinity due to the influence of a spring thaw.     

A Preliminary Study on the Polar Climate Predictability

Studies have revealed that predictability of the atmospheric general circulation is generally high in the tropics throughout the year and that there is some predictability in the Northern extra-tropical winter at-mospheric circulation through some patterns of tele connection. Predictability of the general circulation at the polar regions has still remained as a ‘cold’ topic and little has been known about this question. Based on a preliminary study on the predictability by using the Institute of Atmospheric Physics (IAP) general circulation model, it is found that the SST-related predictability of the Southern winter lower atmospheric circulation in Antarctica is reasonably high and that there is some predictability in the 500 hPa and 200 hPa geopotential height fields over Europe and the Okhotsk Sea region during the Northern winter. It is sug-gested that more researches on this issue based on data analysis and model simulations are needed to obtain better understanding.     

初春南黄海水文特征及环流状况的分析

根据1996年初春中韩黄海水循环动力学合作调查所获资料,分析了南黄海水文特征及其环流状况,并获得了以下几点主要认识:(1)初春南黄海的温、盐分布特征及环流基本形态,与以往所揭示的冬季状况基本相似.然而,本次调查发现,在30m以浅,黄海中部暖水舌轴线比冬季的明显偏东;且出现一范围较小的孤立的相对高温高盐区.在垂向,一种中层冷水和表层逆温跃层现象出现在黄海局部区域.(2)直接测流的结果,不仅部分地印证了由温、盐场所显示的环流基本形态,而且较好地揭示了流场中发生的一些新现象,其中尤其是绕济州岛的流动.(3)黄海暖流水是对马暖流水和陆架水混合而成.而且,它主要是在济州岛西侧水域,从锋带中衍生出来的.     

河西绿洲区春小麦蒸腾蒸散的变化研究

在甘肃张掖绿洲区利用浮力称重式蒸散仪对春小麦蒸散量进行了测定,对蒸散量的日变化和季节变化特征进行了论述。研究结果表明:小麦田的日蒸散量在白天12:00~16:00达到最大,夜间20:00~08:00最小甚至呈负值。灌溉前后蒸腾强度出现峰值的时间有所变化。但灌溉以后,蒸腾与蒸散量均呈增大趋势。日蒸散量随着净辐射的增加而加大。在小麦不同的生育阶段,蒸散量有所不同,小麦拔节以前较小,拔节以后开始增大,灌浆期达到最大,接近成熟时逐渐降低。     

三峡水库香溪河库湾春季水华期间浮游植物昼夜垂直分布与迁移

三峡水库蓄水后,香溪河库湾每年春季均会暴发硅、甲藻水华.为了揭示香溪河库湾水华的暴发规律,于2008年春季对水华期间优势浮游植物的昼夜垂直分布格局及其影响因子进行了研究.利用时间深度等值图模拟浮游植物在水柱中的昼夜垂直分布格局,并用Morisita指数对其进行定量检验,采用修正的K-S test来检验浮游植物是否存在昼...     

Intertidal spring dynamics and coastal nutrient loading revealed through geophysics,drone surveys,and in-situ monitoring

Coastal eutrophication poses an increasing risk to ecosystem health due to enhanced nutrient loading to the global coastline. Submarine groundwater discharge (SGD) represents a significant pathway for nitrate-nitrogen (NO₃-N) transport to the coast, but diffusive SGD transport is difficult to monitor directly, given the low flux rates and expansive discharge areas. In contrast, focused SGD from intertidal springs can potentially be sampled and directly gauged, providing unique insight into SGD and associated contaminant transport. Basin Head is a coastal lagoon in Prince Edward Island, Canada that is a federally protected ecosystem. Nitrate-nitrogen is conveyed from agricultural fields in the contributing watershed to the eutrophic lagoon via intertidal groundwater springs and groundwater-dominated tributaries. We used several field methods to characterize groundwater discharge, nutrient loading, and in-channel mixing associated with intertidal springs. The tributaries and intertidal springs were gauged and sampled to estimate a representative summer nitrate load to the lagoon. Our analysis revealed that NO₃-N export to the lagoon through tributaries and springs throughout summer 2023 was on average 401 kg N/month, with the combined spring loading comparable in magnitude to the combined tributary loading. We collected thermal infrared and visual imagery using drone surveys and found spatial overlap between cold-water plumes from the spring discharge and macroalgae blooms, indicating the local thermal and ecosystem impacts of the focused SGD. We also mapped the electrical resistivity (salinity) distribution in the water column around one large spring with electromagnetic geophysics at different tidal stages to reveal the three-dimensional spring plume dynamics. Results showed that the fresher spring water floated above the saline lagoon water with the brackish plume oriented in the direction of the tidal current. Collectively, our multi-pronged field investigations help elucidate the hydrologic, thermal, and nutrient dynamics of intertidal springs and the cascading ecosystem impacts.     

西北太平洋热带气旋频次的延伸期动力-统计预报方法和评估

介绍了西北太平洋热带气旋(TC)频次的延伸期预报方法,比较了新构建的动力-统计和统计预报模型的预测技巧,并探讨了预报误差来源及改进方向。动力-统计预报模型是基于动力模式预测的热带季节内振荡(ISO)信号及ISO-TC生成的同期统计关系来进行预报;统计预报模型则是基于TC生成的前兆ISO信号建模预报。预报评估结果显示,动力-统计混合预报模型的预报技巧高于统计预报模型,原因在于影响TC次季节变化的前兆信号并不稳定,且随着预报超前时间迅速消散,无法提供有效且稳定的可预报源;相反地,TC生成与同期的ISO背景场显著相关,动力模式对ISO(预报因子)有较好的预报能力,因此动力-统计相结合的预报方法为TC延伸期预报提供了有效途径。虽然目前动力-统计预报模型的预报技巧可达5～6周,但仍有进一步改进和提高的空间。通过对不同类型TC预报技巧检验和误差分析,研究认为年际和年代际背景场对ISO调控TC活动的影响不可忽略,且热带外ISO信号(如罗斯贝波破碎和西风急流强度等)对TC频次和轨迹也有显著影响,这些因子为TC延伸期预报提供了潜在可预报源。