Porphyrin and chlorin distributions in a Late Pliocene lacustrine sediment

The tetrapyrroles in a highly immature Late Pliocene lacustrine sediment (Willershausen, Germany) show a simple distribution of both chlorin and porphyrin components as the free bases. The major components are C32 desoxophylloerythroaetioporphyrin (DPEP), a C33 bicycloalkano porphyrin, the chlorin analogue of the latter, and desoxophylloerythrin and its chlorin counterpart. The structure of the novel bicycloalkano chlorin was determined using a combination of two-dimensional phase-sensitive COSY NMR and nOe studies. Measurements of delta 13C and other data indicate that DPEP and the bicycloalkano porphyrin were derived from the chlorophyll(s) of photosynthetic organisms utilising a common source of CO2, probably diatoms. The occurrence of DPEP and other minor alkyl porphyrins indicates that the chlorophyll defunctionalisation pathway leading to these components can occur at low temperature and was probably biologically mediated, as was the condensation leading to the fused ring components.     

Using nitrate to quantify quick flow in a karst aquifer

In karst aquifers, contaminated recharge can degrade spring water quality, but quantifying the rapid recharge (quick flow) component of spring flow is challenging because of its temporal variability. Here, we investigate the use of nitrate in a two-endmember mixing model to quantify quick flow in Barton Springs, Austin, Texas. Historical nitrate data from recharging creeks and Barton Springs were evaluated to determine a representative nitrate concentration for the aquifer water endmember (1.5 mg/L) and the quick flow endmember (0.17 mg/L for nonstormflow conditions and 0.25 mg/L for stormflow conditions). Under nonstormflow conditions for 1990 to 2005, model results indicated that quick flow contributed from 0% to 55% of spring flow. The nitrate-based two-endmember model was applied to the response of Barton Springs to a storm and results compared to those produced using the same model with δ¹⁸O and specific conductance (SC) as tracers. Additionally, the mixing model was modified to allow endmember quick flow values to vary over time. Of the three tracers, nitrate appears to be the most advantageous because it is conservative and because the difference between the concentrations in the two endmembers is large relative to their variance. The δ¹⁸O-based model was very sensitive to variability within the quick flow endmember, and SC was not conservative over the timescale of the storm response. We conclude that a nitrate-based two-endmember mixing model might provide a useful approach for quantifying the temporally variable quick flow component of spring flow in some karst systems.     

Uptake and depuration of PAHs and chlorinated pesticides by semi-permeable membrane devices (SPMDs) and green-lipped mussels (Perna viridis)

Semi-batch seawater experiments were conducted to follow the uptake and release of selected PAHs (anthracene, fluorathene, pyrene and B[a]P) and organochlorine pesticides (-HCH, aldrin, dieldrin, p,p′-DDT) in semi-permeable membrane devices (SPMDs) and green-lipped mussels (Perna viridis). Mathematical models were applied to describe the uptake and elimination curves of the contaminants for SPMDs, and kinetic parameters, such as uptake rate constants, and equilibrium triolein/water partitioning coefficients were calculated. SPMD data showed a good fit to estimate rate constant and partition coefficient equations, but only those contaminants which partitioned mainly in the dissolved phase (-HCH and dieldrin) were well explained for mussels. Poor conformity of the other contaminants indicated mussels uptake by routes other than diffusion, such as ingestion of algae. An apparent equilibrium state was only noted for -HCH in mussels. Aldrin was not detected in mussels in the first few days of exposure, indicating potential metabolism of this compound. B[a]P was not detected in the triolein of SPMDs, which suggests that the membrane may act as a reservoir. Loss of spiked B[a]P from the triolein was evident in a depuration experiment, which may indicate transfer to the membrane. Rate constants for mussels were higher than those for SPMDs, but the reverse was true for partition coefficients. Overall, mussels and SPMDs had similar uptake rates for all compounds in this study, excluding p,p′-DDT and dieldrin. Contaminant elimination took place more rapidly in mussels, implying that SPMDs are better candidates for detecting episodic discharge of organic contaminants.     

苏联格鲁吉亚地质-地球物理实验场开始工作

据塔斯社报道,一个供地质-地球物理综合实验用的实验场在格鲁吉亚加盟共和国(外高加索)已开始工作。实验场领导人季·加哈里亚对塔斯社记者说,“格鲁吉亚共和国的国土早已是全世界的地质学家、地理学家和气象学家公认的极好的自然实验室,在那里可以实地研究地球及其气候和景观的发育历史。在构造活动迄今仍很活跃的高加索存在着当今非     

欧洲地震委员会第21次大会简介

1.概况:欧洲地震委员会是历史比较悠久的欧洲国际性学术委员会之一,它是国际大地测量和地球物理联合会的成员,还是国际地震学和地球内部物理学协会的一个较大的委员会。这个委员会每二年召开一次大会,会上讨论有关在欧洲开展地震学研究和资料交换的问题,选举委员会的领导班子。欧洲地震委员会第21次大会于1988年8月在索菲亚(保加利亚)召开。这次大会在历届     

苏联哈萨克对住宅的抗震性能实行计算机控制

据塔斯社报道,阿拉木图的科学家们已开始制定哈萨克共和国首都的住宅及其他永久性建筑物的抗震性能说明书。为了分析和保存关于这座超过百万人口的城市内5万幢建筑物中每一幢的强度的资料,建立了专用计算机信息系统。该系统可对地震时有较大危险的所有建筑物予以特殊处理。这样,就可预先对其采取防震加固措施,从而可免遭破坏。之所以需要实行这种说明书制度(首次在苏联实行),其原因是哈萨克的科学家预报该地区内可能发生烈度为Ⅸ—Ⅹ度(按12度烈     

苏联克里米亚强震预报是没有根据的

苏联最近流传的克里米亚地区将发生灾难性地震的“预报”是没有根据的。这是苏联电视台1990年3月2日的报道。电视台的记者之所以在这时采访苏联科学院地球物理研究所的     

地震与太阳活动

苏联国家水文气象委员会北极和南极科研所的瑟京斯基根据大量的统计资料研究了地球的地震活动与太阳和地磁活动以及与行星际介质状态的关系。为了进行分析,利用了从1904年至1977年底期间的年     

月食与地震

地质学家罗曼诺夫报道:1986年10月17日,他在基齐尔-杰列位于达吉斯坦南部)矿区观测到了月全食。当地球的阴影完全遮住月球37分钟之后发生了地震,其震中位置离他不远。当他用苏联科学院达吉斯坦分院地震台站资料进一步核实发震时间和月食最大相的时刻之后