Effects of different types of mechanical disturbances on a charophyte dominated macrophyte community

Charophytes are unique and endangered macroalgae. Mechanical stress is known to damage charophyte communities, however, virtually nothing is known how such disturbance affect seasonal succession and recovery of charophyte communities. We examined the response of a shallow water charophyte community to different types and timing of disturbances by conducting seasonal in situ field experiment in a brackish water ecosystem. The disturbances associated with mechanical removal of vegetation or sediment had the largest impact on the charophyte community. Disturbances that only partly damaged the plants had minor effects and communities were characterized by fast recovery. The timing of disturbance had significant effects on the charophyte community with stronger effects when disturbed at the early stage compared to mid-stage of seasonal succession.     

塔克拉玛干荒漠-绿洲过渡带尘卷风活动特征——以肖塘为例

利用1992—2011年塔克拉玛干沙漠北缘荒漠-绿洲过渡带肖塘气象站的观测资料,分析了该地区尘卷风的年、月变化规律及其与气象因子的关系。结果表明:(1) 1992—2011年尘卷风发生日数总体呈波动递减趋势;尘卷风主要发生在3—9月,占全年总日数的90.9%,其中4—7月占全年总日数的70%左右。(2)尘卷风月发生日数随月平均地表与1.5 m高处温差的增大而线性增加(r=0.875,P<0.01)。(3)尘卷风月发生日数随着月平均风速的增大而幂函数增加(r=0.89,P<0.01)。(4)尘卷风月发生日数随月平均相对湿度的增大而线性减少(r=-0.869,P<0.01)。     

海洋主体功能区划与海洋功能区划关系研究

开展海洋主体功能区划与海洋功能区划的关系和衔接研究,是保障两者在我国海洋事业中充分发挥各自作用的基础.本文从编制及实施2个方面理顺海洋主体功能区划与海洋功能区划的关系,促进两者在实际工作中的相互结合.     

Using otolith weight to predict the age of <Emphasis Type="Italic">Pennahia macrocephalus</Emphasis> in the mouth of the Beibu Gulf

The relation between otolith weight (OW) and the age of marine fish is studied. A total of 222 individuals of bighead white croaker, Pennahia macrocephalus were sampled seasonally in the mouth of the Beibu Gulf, the South China Sea, in 2007. Since there are no significant differences in sagittal OW between otolith in pairs (P≥0.05), the undamaged left sagittal otolith is used for age determination. The highest correlations among standard length, OW and fish ages are confirmed by linear, exponential and multinomial regression. Results show that sagittal OW overlaps only occasionally among age groups, and to individuals with similar standard length, the older and slower-growing fish has a heavier otolith because of the continued otolith material deposition. There are differences in sagittal OW among different age groups and significant positive linear relationship with age (P<0.05). The age readings can be verified by plotting the sagittal OW versus the standard length for age groups, and the individuals with similar standard length but in different ages can be separated by sagittal OW frequency analysis. Mostly, the predicted ages using the regression between sagittal OW and ages are closed to the observed ages by counting annulus on scale. It indicates that the sagittal OW analysis is a useful technique for validating the accuracy of age determination by annuli counts, especially for individuals of similar size. Furthermore, the technique is applied for Pennahia macrocephalus with discussion in this paper. Supported by the National Natural Science Foundation of China (No. 30771653) and Bureau of Fisheries, Ministry of Agriculture     

基于参数空间分布的海洋生态系统模拟

在模拟大尺度海洋生态系统时,由于子区域的生态系统有着各自的特征,导致参数值在空间上存在差异,因此参数在整个研究区域取常数的做法必须改进.基于此,使用气候模式FOAM的气侯态背景场驱动一个简单的三维海洋生态系统模型,并引入参数的空间分布,在全球尺度上通过伴随方法同化SeaWiFS叶绿素资料.引入参数空间分布后,同化结果得到很大改进:浮游植物表层生物量(氮)的平均差从0.155 3减小至0.060 6 mmol·m-3,下降了60.9%,有效地降低了模拟值与观测值在空间上的差异;浮游植物表层生物量平均值也从0.103 1上升至0.125 2 mmol·m-3,更接近SeaWiFS观测.实验结果表明通过引入参数的空间分布来改进海洋生态系统的模拟是可行的.     

1999年11月29日岫岩5.4级地震序列震源参数测定及标度关系分析

根据Andrews谱积分的方法, 采用近震源Brune圆盘模型, 测定了1999年11月29日辽宁岫岩M_S5.4地震序列的震源参数。 结果表明, 得到辐射能量与震级的关系, 与古登堡-里克特给出的关系基本一致; 地震矩与震级的关系中斜率和截距都小于陈培善等给出的全球结果; 视应力与震级呈半对数线性关系; 在双对数坐标下视应力随地震矩的增加而增加; 地震矩随拐角频率的7次方衰减, 在地震序列的不同阶段各参数的拟合关系斜率也不完全相同。     

一种新的流域水沙关系模型及其在年际时间尺度的应用

根据陕西子洲试验站9个流域和山西离石试验站3个流域的观测数据,研究了黄土丘陵沟壑区次暴雨径流和产沙的关系。结果表明:在研究区,当流量超过某一临界值后,含沙量保持稳定,且次洪平均含沙量主要取决于大流量时段,故对于较大的洪水事件,其平均含沙量也趋于稳定,次暴雨和次暴雨过程两个时间尺度的水沙关系表现出很好的相似性。因此可用正比关系式来拟合较大洪水次暴雨径流深和产沙模数之间的关系。由于极端事件对研究区水土流失的重要性,使得该模型有很好的实用性。模型在年际时间尺度上的应用结果表明,对仅在次暴雨期间产流的地区,该模型可以很好地预测年产沙量,而对于常年流水的流域,在丰水年根据汛期径流量该模型也有较好的计算精度。     

从对立到融合：日本的都农关系及都市农业演变研究

把空间概念“都”与产业类别“农”融于一体的“都农关系”,是日本近70年来社会经济发展的重要议题之一。基于对中国城市化发展进入都市化高级阶段,以及乡村振兴亟需多类型化实施的认识背景,对日本都农关系的演变进行历史梳理,划分出都农分离、都农共生和都农融合3个阶段,并从社会经济宏观背景变化的视角说明阶段递进的原因。同时把都市农业视为都农关系的表征,分析其在农户结构、种植结构和功能结构上的系列响应。在此基础上,援引制度学派的基本原理,探索日本都农关系从对立走向融合的制度变迁机理。本文认为,都农融合是不可逆转的潮流,因此有必要把“都农关系”转化为中国的政策性概念,强化从都市区视角处理城乡融合创新发展问题。建设具有中国特色的都农融合和都市农业发展体系,需要一系列的制度创新,也亟需学术界主动的理论探索。     

海洋极端环境微生物活动与油气资源关系

为了弄清海洋极端环境下微生物参与油气资源形成和演化的潜在机制, 进行了现代海洋热泉和冷泉等环境中微生物类型分析和生物量估算, 探讨了极端微生物活动和油气资源的潜在关系.认为海洋极端环境下微生物类型主要为细菌和古细菌, 热泉微生物群落主要为异养发酵菌、硫酸盐还原菌、产甲烷菌等; 冷泉微生物群落主要为ANME-2族的厌氧甲烷氧化古细菌、硫酸盐还原细菌和ANME-1族厌氧甲烷氧化古菌.这些极端微生物利用CH₄和H₂S等气体进行能量固定, 有较高的生物丰度和较低的分异度, 具有垂向和水平分带性, 并能营生一套独特的宏体生物.极端微生物活动直接和间接地参与了油气资源的形成和改造, 示踪海底油气资源的变迁.对于探索地球早期海洋微生物活动与油气资源形成, 寻找地史时期或华南地史早期烃源岩具有重要理论和实践指导意义.      

Sensitivity Analysis of the Super Heavy Rainfall Event in Henan on 20 July (2021) Using ECMWF Ensemble Forecasts

An unprecedented heavy rainfall event occurred in Henan Province, China, during the period of 1200 UTC 19-1200 UTC 20 July 2021 with a record of 522 mm accumulated rainfall. Zhengzhou, the capital city of Henan, received 201.9 mm of rainfall in just one hour on the day. In the present study, the sensitivity of this event to atmospheric variables is investigated using the ECMWF ensemble forecasts. The sensitivity analysis first indicates that a local YellowHuai River low vortex(YHV) in the southe...