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源地黑潮及其上下游流量的变化特征

本文基于长时间序列的海流和温盐资料（最新版SODA高分辩率再分析资料和137°E断面的观测资料），计算了黑潮流系四个主要断面的流量，并分析了它们的变化特征．结果表明，黑潮流系各主要断面流量具有显著的季节性差异，其年际、年代际变化明显．相关分析表明，源地黑潮及其上下游流量变化具有较强的独立性，变化不尽一致，其中，短期气候变化特征可能与热带太平洋的年际变化有明显关联，而年代际变化则可能与发生于北太平洋的年代际变化以及其它副热带中尺度涡旋等变化有一定联系．     

贵州普定喀斯特植被恢复进程研究

喀斯特地区由于其环境的特殊性,人为干扰后植被的恢复有很多不确定性。在普定进行标准木解析和年轮调查,对喀斯特地区植被恢复进程进行研究。结果表明,喀斯特植被在恢复过程中,乔木层表现为高度增加、地径增粗,高度、地径的增长分别呈现对数、乘幂曲线,乔木发育时间连续,生长位置随机分布;而在繁殖体大量存在的情况下,植被可以直接由草灌阶段恢复发育形成次生乔林,且恢复时间明显缩短。     

粤东柘林湾发光细菌法监测生物毒性的周年变化

以发光细菌法监测了粤东柘林湾水体和表层沉积物生物毒性的周年变化,结果表明,所有站位的周年调查中,最低相对发光度为84%,最高为131%,各站位的表层水、底层水和沉积物的相对发光度的年均值都在100%以上,其水体和沉积物均属于低毒或无毒水平,表明该海域尚未被有毒物质污染。由于海水对海洋发光细菌的活化作用,大部分检测样品的发光度都超过对照样品的发光度。监测样品的相对发光度在周年和季节变化上没有规律性,与细菌季节变化的关系不明显,相对发光度的高低与细菌生理群数量的大小没有必然的联系。沉积物样品生物毒性的发光细菌监测方法有待于进一步改善。     

Annual cycle and budgets of nutrients in the Bohai sea

The environmental problems in the Bohai Sea have become more serious in the last decade. High nutrient concentration contributes much to it. A Sino-German cooperation program has been carried out to improve the understanding of the ecosystem by observations and modelling. A three-dimensional ecosystem model, coupled with a physical transport model, is adopted in this study. The simulation for the year 1982 is validated by the data collected in 1982/1983. The simulated annual mean nutrient concentrations are in good agreement with observations. The nutrient concentrations in the bohai Sea, which are crucial to the algal growth, are high in winter and low in summer. There are depletion from spring to summer and elevation from autumn to winter for nutrients. The nutrients’ depletion is a response to the consumption of the phytoplankton bloom in spring. Internal recycle and external compensation affect the nutrient cycle. Their contributions to the nutrient budgets are discussed based on the simulated results. Production and respiration are the most important sink and source of nutrients. The process of photosynthesis consumes 152 kilotons-P and 831.1 kilotons-N while respiration releases 94.5 kilotons-P and 516.6 kilotons-N in the same period. The remineralization of the detritus pool is an important source of nutrient regeneration, It can compensate 23 percent of the nutrient consumed by the production process. The inputs of phosphates and nitrogen from rivers are 0.55 and 52.7 kilotons respectively. The net nutrient budget is −3.05 kilotons-P and 31.6 kilotons-N.     

Annual trace element cycles in calcite–aragonite speleothems: evidence of drought in the western Mediterranean 1200–1100 yr BP

Each of two calcitic stalagmites from Grotte de Clamouse, Herault, southern France, displays a discrete aragonite layer dated at around 1100 yr BP. The layer of fanning aragonite ray crystals is immediately preceded by calcite with Mg and Sr compositions that are uniquely high for the past 3 kyr. Trace element compositions close to the boundary between original aragonite and calcite are consistent with quasi‐equilibrium partitioning of trace elements between the phases. Study of modern dripwaters demonstrates that pronounced covariation of Mg/Ca and Sr/Ca ratios in dripwater occurs owing to large amounts of calcite precipitation upflow of the drips that fed the stalagmites. Trace element to Ca ratios are enhanced during seasonally dry periods. Ion microprobe data demonstrate a pronounced covariation of trace elements, including Mg and Sr in calcite, and Sr, U and Ba in aragonite. The mean peak spacing is close to the long‐term mean of annual growth rates determined by differences in U‐series ages and so the trace element peaks are interpreted as annual. The trace element chemistry of the stalagmites on annual to inter‐annual scales thus directly reflects the amounts of prior calcite precipitation, interpreted as an index of aridity. The longer‐term context is a multi‐decadal period of aridity (1200–1100 yr BP) possibly correlated with an analogous episode in Central America. The arid period culminated in the nucleation of aragonite, but within a decade was followed by a return to precursor conditions. Copyright © 2005 John Wiley & Sons, Ltd.     

花园口站年最大洪峰流量时间序列的HHT分析

Hilbert-Huang变换能够定量描述非线性、非平稳复杂时间序列的时频特性,较传统分析方法更具优势。通过对时间序列进行EMD分解,得到变化过程的内在模态函数和趋势项函数,而后对各内在模态函数进行Hilbert-Huang变换,从而揭示出时间序列的多时间尺度特征。以黄河花园口站1952-2009年的年最大洪峰流量时间序列为例,对其进行多时间尺度分析,得到不同波动周期的振荡分量及趋势分量,具体分析了各分量的变化特征。结果表明,花园口年最大洪峰流量变化过程中存在准3.2a、准6.4a、准11.8a和准31.0a周期的波动,其中准3.2a和准6.4a的周期波动是引起原序列波动的主要原因,近60年来花园口年最大洪峰流量变化呈递减趋势,由此揭示了年最大洪峰流量变化过程的多时间尺度特征。在此基础上,探讨了各波动分量变化的影响因素,其变化与大气低频振荡、ENSO、太阳活动及气候变迁等因素有关。