福建沿岸6000年来的海平面波动

本文通过35个~(14)C测年数据进行评价,建立一条福建省沿岸过去6000年海平面变化曲线,该线表明海平面在现代位置上下呈振荡性变化,最高和最低海平面分别出现距今5000年前和4000年前左右,海平面高度分别为约+2m,-2m。     

Multifractal analysis of spatial distribution of microearthquakes in the Kanto region

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The spatial distribution of earthquakes is a fractal, which is characterized by a fractal dimension. However, if a spatial distribution has a heterogeneous fractal structure, a single value of fractal dimension [e.g. D_o (capacity dimension) or D ₂ (correlation dimension)] is not enough to characterize it. From a multifractal viewpoint, we analysed the spatial distribution of microearthquakes in the Kanto region by using a local density function. Generalized dimensions, D_q , of the spatial distribution were calculated from the slopes of generalized correlation integrals, C_q(r) versus distance r , on a log-log plot, examining the self-similarity of the spatial distribution of microearthquakes. Self-similar structures are held well at scales from 1.26 to 12.6 km. Our results suggest that the spatial distribution of microearthquakes in the Kanto region is not a homogeneous fractal structure but a heterogeneous one with generalized dimensions D₂ = 2.2 ≤ D ₃≤…≤ D _∞= 1.7. The value of D _∞, the lower limit of fractal dimension, is the fractal dimension of the most intensive clustering in the heterogeneous fractal set. The fractal dimension of the most intensive clustering of microearthquakes in the Kanto region is 1.7.     

Study of phytoplankton community in the channel from Dongting Lake to Changjiang River, China

1 INTRODUCTION Dongting Lake (28°18'–29°45'N, 111°35'– 113°18'E) is the second largest freshwater lake in China, and directly connected with the Changjiang River (Yangtse River) through the channel. The sur- face area was about 2 740 km2 (at the low     

汕头台地下流体正常动态与地震短临异常

地震前兆观测异常信息识别是前兆研究的基础.分析了汕头观测站地下流体各测项如水位、水温、气氡和气汞等观测资料,对其正常动态和短临异常信息进行了讨论.结果表明,上述各测项能够较有效地反映出某些中等地震前兆的短临异常信息.     

相关函数法计算相关距离的分析探讨

根据数百个土层土性参数相关距离的计算, 对相关函数法计算相关距离的方法、相关函数型式选择、拟合范围等问题进行了分析探讨。     

辽宁西部地区的气候变化及干湿状况年代际变化特征

辽宁西部(简称辽西)是气候及生态环境脆弱区,因其特殊性使之成为相关科研人员关注的焦点,在全球气候变暖背景下增温显著的辽西地区气候及地表干湿气候界线如何变化是本文研究的问题。应用1961—2004年辽宁省内52个气象站的温度、降水、湿度、风、日照等气候资料,分析了辽西近50 a来的气候变化特点,采用改进的Penman模型计算潜在蒸发量,讨论了其时空代表性及分布特征;进一步计算了干燥度指数,并在10 a代际尺度上详细分析了辽西干湿气候变化特征。研究表明:辽西地区近44 a的总体气候变化趋势是气温升高、降水减少。20世纪60年代以来该区域干湿气候界线波动显著,呈现出整体移动、南北异相波动的特征。干湿气候年代际变化特征为60年代最湿润;70年代北部明显变干,南部不明显;80年代干湿气候存在一次突变,半干旱与半湿润界线明显东移,为最干期;90年代又跳跃性西移,明显变湿,尤其在北部表现更为显著,接近60年代。辽西的气候干湿年代际变化与西太平洋副热带高压和东南季风波动有较好的对应关系。     

藏南沉错湖泊三角洲的沉积相及沉积环境

在西藏自治区沉错湖泊三角洲平原和湖内钻孔取芯 ,利用14 C和ESR测年方法建立了钻孔剖面的年代标尺。在岩芯描述、沉积物粒度分析和CaCO3含量分析基础上 ,对沉错湖泊三角洲的沉积环境和沉积相进行了解释分析。 36 7m长的岩芯大致记录了 5 5万年以来的沉积历史。全孔平均沉积速率约为 0 6 6 7mm/a。 16 92 0aBP以来三角洲的沉积速率较大 ,平均为 1 2 7mm/a。由于沉积物物质来源的多源性导致CaCO3在剖面上的无规律性变化。但是 ,沉积物粒度和沉积序列变化指示全套沉积由底部的冲积扇相向上过渡为水下扇亚相和三角洲沉积相。在大约 175 0 0aBP～ 14 0 0 0aBP时期 ,沉错存在高湖面阶段。沉积序列中记录了末次冰期最盛期 (LastGlacialMaximum )和新仙女木事件 (YoungerDryas)。沉积特征和沉积环境的变化主要受湖面涨缩变化所控制。而湖面升降变化的驱动因素主要为气候 ,尤其夏季风的强弱和冷事件     

Quantification of peatland water storage capacity using the water table fluctuation method

Peat specific yield (S_Y) is an important parameter involved in many peatland hydrological functions such as flood attenuation, baseflow contribution to rivers, and maintaining groundwater levels in surficial aquifers. However, general knowledge on peatland water storage capacity is still very limited, due in part to the technical difficulties related to in situ measurements. The objectives of this study were to quantify vertical S_Y variations of water tables in peatlands using the water table fluctuation (WTF) method and to better understand the factors controlling peatland water storage capacity. The method was tested in five ombrotrophic peatlands located in the St. Lawrence Lowlands (southern Québec, Canada). In each peatland, water table wells were installed at three locations (up‐gradient, mid‐gradient, and down‐gradient). Near each well, a 1‐m long peat core (8 cm × 8 cm) was sampled, and subsamples were used to determine S_Y with standard gravitational drainage method. A larger peat sample (25 cm × 60 cm × 40 cm) was also collected in one peatland to estimate S_Y using a laboratory drainage method. In all sites, the mean water table depth ranged from 9 to 49 cm below the peat surface, with annual fluctuations varying between 15 and 29 cm for all locations. The WTF method produced similar results to the gravitational drainage experiments, with values ranging between 0.13 and 0.99 for the WTF method and between 0.01 and 0.95 for the gravitational drainage experiments. S_Y was found to rapidly decrease with depth within 20 cm, independently of the within‐site location and the mean annual water table depth. Dominant factors explaining S_Y variations were identified using analysis of variance. The most important factor was peatland site, followed by peat depth and seasonality. Variations in storage capacity considering site and seasonality followed regional effective growing degree days and evapotranspiration patterns. This work provides new data on spatial variations of peatland water storage capacity using an easily implemented method that requires only water table measurements and precipitation data.     

A general solution for groundwater flow in an estuarine's leaky aquifer system after considering aquifer anisotropy

This paper presents an analytical model for describing the tidal effects in a two‐dimensional leaky confined aquifer system in an estuarine delta where ocean and river meet. This system has an unconfined aquifer on top and a confined aquifer on the bottom with an aquitard in between the two. The unconfined and confined aquifers interact with each other through leakage. It was assumed that the aquitard storage was negligible and that the leakage was linearly proportional to the head difference between the unconfined and confined aquifers. This model's solution was based on the separation of variables method. Two existing solutions that deal with the head fluctuation in one‐dimensional or two‐dimensional leaky confined aquifers are shown as special cases in the present solution. Based on this new solution, the dynamic effect of the water table's fluctuations can be clearly explored, as well as the influence of leakage on the behaviour of fluctuations in groundwater levels in the leaky aquifer system. Copyright © 2015 John Wiley & Sons, Ltd.     

青藏高原第四纪冰川作用及其气候响应的讨论

关于青藏高原和周边山地第四纪冰川作用及其气候响应存在不同观点.一些学者认为老冰期主要发生在氧同位素奇数阶段;MIS 3和早全新世存在规模较大的冰川前进;南亚季风对青藏高原冰川作用起主导作用(水汽驱动).另一些学者则认为青藏高原冰川作用主要对应于氧同位素偶数阶段;冰川发育是构造隆升-冰期气候耦合的产物(低温驱动).本文基于现有的陆地生成宇宙核素(TCN)和光释光(OSL)等年代结果总结了不同时间尺度和不同类型冰川波动与气候变化历史的对比,并对几个关键的争议问题做了讨论.结果表明,在不同类型冰川区和不同时间尺度下,冰川作用在湿润期和低温期都有可能发生,但总体上主要与低温相对应.青藏高原冰川对气温的响应似乎更为敏感.MIS 3冰进规模较大可能是降水较多结合冷期(或冷事件)降温所致,显示了印度季风降水和气温波动对高原冰川的共同作用.早全新世冰进也与印度季风和北半球冷事件关系密切.目前的测年数据还没有推翻“冰期发生在氧同位素偶数阶段”这种传统认识.当前急需更多精确的数字定年工作,以不断更新对青藏高原冰期时代及其气候响应机制的了解.