Managing coastal bathing water quality: the contribution of microbiology and epidemiology

The EU Bathing Water Directive with a life of 25 years (EEC, 1976) has contributed significantly to the improvement of the quality of coastal recreational waters throughout Europe and has successfully protected public health. Improvement of the standards of living and general public demands has made it necessary to consider updating it (EU, 1994) introducing important changes in microbiological parameters. Measurement of microbial pollution is of primary importance to this new proposal, as is to the regulatory schemes introduced by the very recent 'Annapolis Protocol' (WHO/US EPA, 1999). This report discusses the microbiological aspects of the health-related management of bathing seawater in the context of the scientific information available from epidemiological and microbiological studies.     

Anomalous Enrichment of Silver in Organic Matter of the Songxi Shale-hosted Ag-Sb Deposit in Northeastern Guangdong

The silver contents of organic matter in the host rocks of the Songxi shale-hosted Ag-Sb deposit of northeastern Guangdong, South China, have been directly determined using the electron microprobe technique. The silver contents in two types of organic matter, marine vitrinite and solid bitumen, vary in the range from 100×10-6to 350×10-6, which are from tens of times to thousands of times higher than those of the host rocks in the ore deposit. The average silver content of the organic matter is also several times higher than the pay grade of silver for commercial mining of the ore deposit. It is quite obvious that the organic matter of the host rocks in the ore district is characterized by an anomalous enrichment of silver. The results of this study indicate that the silver anomalies in the organic matter have been derived from both the host rocks and the silver-bearing fluids of the Songxi black shale ore source. In the course of sedimentation and later hydrothermal reworking, organic matter was able     

Flow Characteristics of Large-Scale Liquefaction-Slip of the Loess Strata in Shibei Tableland, Guyuan City, Induced by the 1920 Haiyuan M8 1/2 Earthquake

Based on the dynamic triaxial liquefaction test of the loess samples which are taken from Shibei tableland, Guyuan City, Ningxia, China, the characteristics of dynamic strain, dynamic stress and pore water pressure are studied under cyclic loading. Triaxial shear test is conducted immediately after the sample reaches liquefaction point. During the test, the property of the liquefied soil is analyzed through fluid mechanics method, whereby the fluidity of the liquefied soil is represented by apparent viscosity.The results show that the fluidity of liquefied loess changes from "shear thickening" to "shear thinning" as the shear force continues, and the fluidity of liquefied loess is closely related to its structure. In addition, in the process of forming a new stable state, the apparent viscosity and deviant stress change with axial strain in a similar approach. When the sample reaches its stable state, it meanwhile shows a relatively stable apparent viscosity. According to the fluid mechanics and the law of conservation of energy, the slip distance of the liquefied soil is estimated, and the results are in good agreement with the field investigation results.     

Mercury in sediments of Ulhas estuary

Hg levels in water, suspended particulate matter and sediment of the Ulhas estuary are under considerable environmental stress due to the indiscriminate release of effluents from a variety of industries including chlor-alkali plants. Concentration ranges of dissolved (0.04-0.61 micro gl(-1)) and particulate (1.13-6.43 micro gg(-1)) Hg reveal a definite enhancement of levels in the estuary. The Hg burden in sediment upstream of the weir that limits the tidal influence is low (0.08-0.19 micro gg(-1)) with low C(org) content (1.8-2.9%). The high Hg content of the sediment just below the weir varies seasonally (highest concentration recorded being 38.45 micro gg(-1)) due to incremental accretion of sediment as the fresh water flow over the weir progressively decreases. The 30 km segment of the estuary sustains markedly high levels of Hg in the sediment with an exponential decrease in the seaward direction from the weir. Higher concentrations than the expected background prevail in all the estuarine cores up to the bottom, though the overall concentration decreases from about 20 micro gg(-1) in core 7 (inner estuary) to 1 micro gg(-1) in core 31 (outer estuary). The Hg in sediment is associated with C(org), while its correlation with Al, Fe and Mn is poor. The Hg profiles in cores from the Arabian Sea (stations 34, 35 and 37) have a distinct horizon of enhanced concentration in the 5-60 cm segment. Based on 210Pb dating of core 37, the sediment at the bottom of this core is inferred to have been deposited in the year 1949, roughly two year prior to the establishment of the first chlor-alkali plant and represents the background (0.06-0.10 micro gg(-1)). The Hg profiles in the offshore cores indicate a marked increase in transfer of Hg to sediment subsequent to 1980, with a peak around 1990-1992. Based on the index of geoaccumulation it is considered that the estuarine segment between stations 4 and 23 is extremely polluted, while the sediment from the open coast is moderately polluted in the top 25-30 cm with respect to Hg. The enrichment factor of Hg in the sediment is 350-700 for core 4 and decreases to 0-7 for the open-shore cores.     

Ground water flow analysis of a mid-Atlantic outer coastal plain watershed, Virginia, U.S.A

Models for ground water flow (MODFLOW) and particle tracking (MODPATH) were used to determine ground water flow patterns, principal ground water discharge and recharge zones, and estimates of ground water travel times in an unconfined ground water system of an outer coastal plain watershed on the Delmarva Peninsula, Virginia. By coupling recharge and discharge zones within the watershed, flowpath analysis can provide a method to locate and implement specific management strategies within a watershed to reduce ground water nitrogen loading to surface water. A monitoring well network was installed in Eyreville Creek watershed, a first-order creek, to determine hydraulic conductivities and spatial and temporal variations in hydraulic heads for use in model calibration. Ground water flow patterns indicated the convergence of flow along the four surface water features of the watershed; primary discharge areas were in the nontidal portions of the watershed. Ground water recharge zones corresponded to the surface water features with minimal development of a regional ground water system. Predicted ground water velocities varied between < 0.01 to 0.24 m/day, with elevated values associated with discharge areas and areas of convergence along surface water features. Some ground water residence times exceeded 100 years, although average residence times ranged between 16 and 21 years; approximately 95% of the ground water resource would reflect land use activities within the last 50 years.     

Critical Self-Organization of Astrophysical Shocks

There are two distinct regimes of the first-order Fermi acceleration of shocks. The first is a linear (test-particle) regime in which most of the shock energy goes into thermal and bulk motions of the plasma. The second is an efficient regime in which the shock energy goes into accelerated particles. Although the transition region between them is narrow, we identify the factors that drive the system toward a self-organized critical state between those two regimes. Using an analytic solution, we determine this critical state and calculate the spectra and maximum energy of accelerated particles.     

Radio Emission from Three-dimensional Relativistic Hydrodynamic Jets: Observational Evidence of Jet Stratification

High-resolution, high signal-to-noise ratio, blue-violet spectra of three red giant branch tip stars in M15 have been obtained with the Keck I High-Resolution Echelle Spectrograph. These spectra have been analyzed to determine the abundances of several neutron-capture elements, including the radioactive chronometer element thorium. There are two principal results of this study. First, the abundances of the heavier (Z>/=56) elements for each of the three stars is well matched by a scaled solar system r-process abundance distribution. Second, a weighted mean-observed Th/Eu ratio for the stars implies an age for the neutron-capture material in M15 stars of 14+/-3 Gyr, in reasonable agreement with other recent age estimates for Galactic globular clusters.     

柴北缘—东昆仑地区造山型金矿床的流体包裹体研究

柴达木盆地北缘(以下简称柴北缘)—东昆仑地区已经勘查发现了一批造山型金矿,它们是加里东和晚华力西—印支复合造山作用的产物。通过柴北缘—东昆仑地区12处造山型金矿中流体包裹体研究发现,该区造山型金矿中发育两种不同的成矿流体:低盐度的H2O-CO2-NaCl-CH4流体和低盐度的H2O-CO2-NaCl±CH4。前者的XCH4、XCO2和XH2O分别为0.14～0.34(平均值0.24)、0.11～0.59(平均值0.34)和0.64～0.31(平均值0.42),温度变化为180～270℃,压力为180～560Mpa,是晚加里东期碰撞造山作用的产物,主要沿加里东碰撞造山带边界的上地壳底部-中地壳上部的塑性变形带大规模流动,并在本区形成了广泛的金矿化;后者的XCH4、XCO2和XH2O分别为0～0.12(平均值0.06)、0.18～0.25(平均值0.21)和0.79～0.69(平均值0.73),温度变化为280～449℃(主要在280～360℃),压力为80～230Mpa,主要与晚华力西—印支期碰撞造山作用有关,其中不少矿床还受侵入岩浆作用的影响,其沿晚华力西—印支期碰撞造山带边界的上地壳大规模流动,导致了本区造山型金矿的最终定位。上述两期成矿流体的盐度相差不大,总体变化在1.4%～11.4%(NaCl)(大部分集中于2.7%～9.1%)。压力-深度换算结果显示,本区晚华力西—印支期碰撞造山作用表现出地壳强烈隆升过程,其最大隆升幅度达12km。这说明该区大规模的造山型金成矿作用发生在地壳隆升的背景之下。     

管得住 用得好——吉林市矿产资源开发利用工作综述

吉林市既是国家提出振兴东北老工业基地的前沿城市,又是一个以化工、电力、冶金、建材为主的原材料加工型城市,对矿产资源的的依赖程