Use of the clam Asaphis deflorata as a potential indicator of organochlorine bioaccumulation in Hong Kong coastal sediments

In order to test its ability as a bioaccumulator, the deposit feeding clam Asaphis deflorata, collected from a clean coastal area in Hong Kong (Ding Chau, Ma On Shan), was exposed to field-collected sediments representing a gradient of contamination. Sediments were collected from four sites, namely Shek O in the southeast of Hong Kong Island, Ap Lei Chau in Aberdeen district, Tai Kok Tsui in the Mong Kok waterfront, and To Kwa Wan near Kowloon City pier. Shek O was the cleanest and To Kwa Wan was the most polluted site. Replicate 30L fiberglass tanks containing equal numbers of organisms were maintained for 28 days, with equal quantities of sediment and filtered seawater. Prior to this the animals were depurated for 10 days in clean sediment. During the 28-day holding period, sampling of both sediment and clams was performed on days 0, 10 and 28, along with condition index measurements. Concentrations of organochlorine pesticides and PCBs in sediments showed that Shek O was the cleanest of the sites, followed by Ap Lei Chau, Tai Kok Tsui and To Kwa Wan. There were marked differences among the sites, especially in PAH concentrations, with To Kwa Wan showing extremely high sediment concentrations. Following exposure, the biota concentrations of various organochlorine pesticides and PCBs suggested that there was sediment concentration-dependent accumulation by A. deflorata on day 10 of the experiment. However, there was no significant increase on day 28 for any of the compounds tested. Contaminant concentrations in clams feeding on Shek O sediments were minimal and almost the same on all sampling days, indicating the presence of only baseline contaminant concentrations. The condition indices (CI) of the clams on various sampling days showed that the animals were relatively more stable in sediment from Shek O. There were some deaths in all the test tanks (including those containing Shek O sediments). In addition, clams appeared to bury faster in the cleaner Shek O sediment and remained buried, unlike those in the sediment from the other locations, where some remained predominantly on the surface. Nevertheless, despite not completely burying, the clams in other test sediments still exhibited sediment concentration-dependent tissue accumulation. The results of the investigation indicate the possibility of developing a standard test protocol for bioaccumulation by sediment dwelling invertebrates, for practical use in Hong Kong, using A. deflorata.     

观察自然的地震窗——古宾谈地震构造规律

苏联科学院通讯院士、地质矿物学博士古宾对不同地区(其中也包括塔吉克斯坦)的地质构造及其沿断层发生的孕震运动进行了半个多世纪的研究,确定了人们过去还不知道的地震能量与地震构造(地壳块体)尺度和类型之间有规律性的数值关系。这种综合性关系被称为古宾地震构造规律。这个规律不仅能导致建立预报地震各种不同要素的新(原则上)方法,而且还能导致绘制出完全新的、反映许多要素的地震区划图(标出可能     

日本本州岛地区地震活动频繁

据塔斯社1988年6月27日至8月6日发自东京的电讯报道:日本的本州岛地区地震活动频繁,强度为日本气象厅7度烈度标度的1至     

苏联地质部长谈苏联的地质勘探工作

根据对地壳和地幔所有构造层进行的综合观测,苏联已经完成了对地球深部的新研究。苏联地质部长科兹洛夫斯基在会见塔斯社记者时说,这些研究工作对许多国家的专家也具有重大的科学和实际意义。这位部长还说,新型的地球物理仪器,技术手段和先进的钻探工序为研究工作的成功提供了主要保证。部长首先介绍了科拉半岛(苏联国土欧洲部分的北部)和萨阿特雷(外高加索)超深井的试钻情况,这些超深井已提供了关于地球深部的构造和所发生过程的丰富资料;然后他又介绍了苏联2000年以前在辽阔国土上进行深部     

Biological marker distribution in coexisting kerogen, bitumen and asphaltenes in Monterey Formation diatomite, California

Organic-rich (18.2%) Monterey Formation diatomite from California was studied. The organic matter consist of 94% bitumen and 6% kerogen. Biological markers from the bitumen and from pyrolysates of the coexisting asphaltenes and kerogen were analyzed in order to elucidate the relationship between the various fractions of the organic matter. While 17 alpha(H), 18 alpha(H), 21 alpha(H)-28,30-bisnorhopane was present in the bitumen and in the pryolysate of the asphaltenes, it was not detected in the pyrolysates of the kerogen. A C40-isoprenoid with "head to head" linkage, however, was present in pyrolysates of both kerogen and asphaltenes, but not in the bitumen from the diatomite. The maturation level of the bitumen, based on the extent of isomerization of steranes and hopanes, was that of a mature oil, whereas the pyrolysate from the kerogen showed a considerably lower maturation level. These relationships indicate that the bitumen may not be indigenous to the diatomite and that it is a mature oil that migrated into the rock. We consider the possibility, however, that some of the 28,30-bisnorhopane-rich Monterey Formation oils have not been generated through thermal degradation of kerogen, but have been expelled from the source rock at an early stage of diagenesis.     

Quantitative interpretation of specific conductance frequency distributions in karst

Use of the coefficient of variation (CV) of specific conductance has been a simple and popular approach to classifying karst aquifers; however, problems with this approach arise because specific conductance frequency distributions (CFDs) are usually multimodal and the use of the CV sometimes erroneously classifies aquifers in terms of their dominant flow type or recharge type. Here, we demonstrate a more rigorous analysis of the CFD, which gives insight into the water types contributing to spring flow. The CFD for a water year is separated into an additive series of normal distributions, each related to a hydrogeochemical population. For each water type, its mean, variance, and contribution to the overall CFD can be quantified and compared between water types and water years. We applied this method to 4 years of data collected at Barton Springs, Austin, Texas. Although the overall shape of the CFD changed from year to year, it could consistently be separated into the same set of normally distributed populations. We suggest that each population represents a water type resulting from a particular mode of aquifer functioning. Changes in the parameters describing the curves reflect aquifer response to climatic variations. The results suggest that no single parameter of specific conductance can be used to describe the degree of karst behavior of an aquifer but that the degree of karst behavior itself varies from year to year depending on hydrologic conditions.