Preliminary study on characteristics of earthquake precursor of earth resistivity anisotropy degree in East China

Introduction The degree of earth-resistivity anisotropy was described (MAO, et al, 1995, 1998) as follows: S=|1\nn∑I=1(ρSN\ρEW)I|-1|×103 n=6(1) whereρNS and ρEW are monthly mean values of earth resistivity in the direction of NS and EW, respectively, S is the half-year value. Equation (1) shows that if ρNS=ρEW, then S =0 and the electrical property of medium is isotropic; if ρNS≠ρEW, then S≠0 and the electrical property of medium is anisotropic. When S increases, the anisotropy of electrical property of medium is enhanced. Because the rightside of equation (1) is absolute value and the possibility ofρNS＞ρEW and ρNS＜ρEW can be different at different stations, the increase or decrease of S cannot reflect the relative changes between ρNS and ρEW. FENG, et al (2000) defined S as follows:     

Trace organic contamination in biota collected from the Pearl River Estuary, China: a preliminary risk assessment

The marine ecosystem of the Pearl River Delta, located on the southern coast of China, has been heavily exploited following the rapid economic growth that has occurred since the 1980s. This investigation aimed to elucidate trace organic contamination in marine biota inhabiting the Pearl River Delta area. Biota samples, including green-lipped mussels (Perna viridis), oysters (Crassostrea rivularis) and shrimp (Penaeus orientalis) were sampled from 16 stations fringing the Estuary. Elevated concentrations (on a dry weight basis) of polycyclic aromatic hydrocarbons (27.8–1041.0 ng/g), petroleum hydrocarbons (1.7–2345.4 μg/g), polychlorinated biphenyls (2.1–108.8 ng/g), DDTs (1.9–79.0 ng/g), and hexachlorocyclohexanes (n.d.–38.4 ng/g) were recorded. A human health risk assessment was conducted to estimate the risk to local residents associated with the consumption of biota collected from the Pearl River Estuary. The results indicated that PCBs were at levels that may cause deleterious health effects in populations that consume large amounts of seafood. However, it would be instructive to establish health criteria for trace organic contaminants that are specific to the local populations, in order to derive a more accurate and relevant health risk assessment.     

Carbon isotopic fractionation associated with lipid biosynthesis by a cyanobacterium: relevance for interpretation of biomarker records

For the cyanobacterium Synechocystis UTEX 2470, grown photoautotrophically to a logarithmic stage of growth, the total lipid extract is depleted in 13C by 4.8% relative to average biomass. Depletions observed for acetogenic (straight-chain) lipids range from 7.6 (hexadecanoic acid) to 9.9% (a C16 n-alkyl chain bound in a polar-lipid fraction), with a mass-weighted average of 9.1%. Polyisoprenoid lipids fall into two isotopic groups, with phytol, diplopterol, and diploptene depleted by 6.4-6.9% and bishomohopanol (produced from the extracts by the preparative degradation of bacteriohopanepolyol) depleted by 8.4%. Analysis of the pattern of depletions indicates that two carbon positions in each C5 biomonomer leading to polyisoprenoid products are probably depleted in 13C relative to average biomass. The depletion of bacteriohopanepolyol relative to other polyisoprenoids can be ascribed to changes that occur over the life of each cell: (1) the 13C content of carbon flowing to lipid biosynthesis decreases as the cell size increases and (2) a greater proportion of the bacteriohopanepolyol which, unlike other polyisoprenoids, is present mainly in the cytoplasm rather than in membranes and is synthesized when cells are larger. Chlorophyll a is depleted relative to average biomass by O.7%. Given the observed depletion of 13C in phytol, the heteroaromatic, chlorophyllide portion of chlorophyll must be enriched in 13C by 2.7%. This enrichment is large relative to that in chlorophyllides produced by eukaryotes and may be related to a parallel enrichment of 13C in cyanobacterial glutamic acid. As in many previous investigations of cyanobacterial lipids, long-chain n-alkanes (C22-C29) are found in the extracts. They are, however, enriched in 13C relative to biomass and have isotopic compositions suggesting that they are contaminants of petrochemical origin. Available results indicate that cyanobacterial lipids will be depleted relative to dissolved CO2 that has served as a carbon source by 22-30% and that a wider range of depletions will be characteristic of eukaryotic products. The absence of long-chain n-alkanes in cyanobacteria reduces the possibility that petroleum ever formed from pre-eukaryotic sedimentary debris.     

1668年郯城8.5级地震震源参数及其讨论

利用野外考察资料系统地计算和屯１６６８年郯城地震的震源参数，讨论了其特点进而提出了计算地震断层动摩擦阻力和应力的公式，给出了衡量地震断层破裂彻底度的判别指标和主震后强余震的预测方法。     

鲁07井水位对固体潮滞后的处理

本文给出了一种计算考虑滞后影响的井水位固体潮系数的新方法，导出了计算固体潮系数和滞后时间的公式，给出了考虑滞后影响的井水位固体潮校正公式。以鲁07井为例，用该法求出其井水位固体潮系数为16.5mm/10^-8，水位对固体潮响应的滞后时间为0.48小时，与以胶的回归分析方法相比，校正后的水位中误差明显减小，校正效果比较好。     

唐山地震地下水不位动态图象及其预报意义

采用水位滑动变差方法,研究了唐山地震前后地下水位时空演化特征。研究结果表明,水位滑动变差方法是突出地下水位前兆场时空演化特征的良好方法。唐山地震前后地下水位动态图像正负区和异常特征区的时空演化具有明显的规律性和阶段性。负值区的演化具有“收缩－扩展－急速扩展－发震”的特征;异常特征区的演化显示“迁移－扩展－稳定－发震－消失”的特征;滑动变差显示“增大－减小－发震－急速减小”的变化过程。据此给出了地震