The distribution and sources of polycyclic aromatic hydrocarbons in Narragansett Bay surface sediments

Polycyclic aromatic hydrocarbons (PAHs) were measured in 41 surface sediments from Narragansett Bay, RI. All the analytes generally decrease down bay from the Seekonk, Providence and Taunton Rivers at the head of the bay. Total PAHs ranged from 0.569 to 216 microg/g with 27% exceeding the effects range median (ERM) of 44.8 microg/g and 73% of the stations exceeding the effects range low (ERL) of 4.02 microg/g (Long et al., 1995). Based on principal component analysis, the major source of the contaminants in Narragansett Bay was the Providence River while the coves and Taunton River/Mt. Hope Bay appeared to only have a limited influence on the open bay. PAH source ratios indicate that creosote and/or coal may be the most significant contributor of pyrogenic high molecular weight PAHs in Narragansett Bay, along with significant contributions from diesel exhaust.     

Thomson Thick X-Ray Absorption in a Broad Absorption Line Quasar, PG 0946+301

We present results of new ASCA observations of the low-luminosity active galactic nucleus (LLAGN) NGC 4579 obtained on 1998 December 18 and 28, and we report on the detection of variability of an iron K emission line. The X-ray luminosities in the 2-10 keV band for the two observations are nearly identical (LX approximately 2x1041 ergs s(-1)), but they are approximately 35% larger than that measured in 1995 July by Terashima et al. An Fe K emission line is detected at 6.39+/-0.09 keV (source rest frame), which is lower than the line energy 6.73+0.13-0.12 keV in the 1995 observation. If we fit the Fe lines with a blend of two Gaussians centered at 6.39 and 6.73 keV, the intensity of the 6.7 keV line decreases, while the intensity of the 6.4 keV line increases, within an interval of 3.5 yr. This variability rules out thermal plasmas in the host galaxy as the origin of the ionized Fe line in this LLAGN. The detection and variability of the 6.4 keV line indicates that cold matter subtends a large solid angle viewed from the nucleus and that it is located within approximately 1 pc from the nucleus. It could be identified with an optically thick standard accretion disk. If this is the case, a standard accretion disk is present at the Eddington ratio of Lbol/LEdd approximately 2x10-3. A broad disk-line profile is not clearly seen, and the structure of the innermost part of accretion disk remains unclear.     

Survival, growth, metallothionein and glycogen levels of Nucella lapillus (L.) exposed to subchronic cadmium stress: the influence of nutritional state and prey type

Dogwhelks Nucella lapillus feed mainly on mussels and barnacles, and may experience periods of starvation. We report effects of nutritional state and prey type on the survival, growth, cadmium (Cd) accumulation, metallothionein (MT) induction and glycogen stores in N. lapillus exposed to Cd in water. Adult dogwhelks, with similar shell length (30.0+/-1.5 mm), were either starved or fed to satiation with barnacles Semibalanus balanoides, mussels Mytilus edulis or Cd-dosed M. edulis, and kept in filtered natural seawater (< 0.01 microg Cd 1(-1)) or Cd-contaminated (400 microg Cd 1(-1)) seawater for 80 days. Mortality and individual growth rate were determined. Cd, MT and glycogen were measured in different tissues. Prolonged starvation and exposure to Cd significantly reduced the survivorship of N. lapillus, but feeding could help dogwhelks to combat Cd toxicity and minimise mortality. Extended starvation also caused tissue wastage, leading to higher concentrations of Cd and MT in tissues, whereas fed animals increased in weight and had lower Cd and MT concentrations because of the tissue dilution effect. Prey type significantly affected growth rate of dogwhelks and indirectly influenced Cd accumulation, MT induction and glycogen stores. Eating mussels promoted better growth and higher glycogen reserves than eating barnacles. Individual growth rate decreased with increasing Cd accumulation. Cd-exposed survivors grew faster and consumed more than control animals, implying that these survivors may have better fitness and greater tolerance to Cd toxicity. The use of growth, condition index, MT and glycogen as biomarkers of environmental pollution are discussed. These results indicate a need to incorporate biological data including growth (or at least condition index) and prey type into biomonitoring programmes to allow sound interpretation.     

澳大利亚南部Gambier海湾卡洛林CO2气田及有关的CO2产状

虽然ＣＯ２气田在地理上分布很广，但地下高纯ＣＯ２气比较少见。在Ｏｔｗａｙ盆地海湾内部，已经钻遇了两个ＣＯ２气圈闭，其中Ｋａｌａｎｇａｄｏｏ１井产气１４７吨／天（２．８百万立方英尺／天），卡洛林１井产气１４２吨／天（２．７百万立方英尺／天）。澳大利亚的唯一一口生产商业ＣＯ２的井是联盟公司卡洛林１井，年产液态ＣＯ２１５０００吨。处理方法主要限于用单一分馏法处理掉井口气液中含量的１％的烃。Ｋａｌａｎｇａ     

地壳增长与壳—幔再循环

在会聚边缘的地壳增长目前是由地壳从地幔中的萃取作用所支配的,这是一个只能间接观察到的过程。在现代的会聚边缘,常见于地壳最上部的玄武岩和安山岩(及相应的侵入岩)并非直接源于地幔(如它们不是地幔的初始成分)。例如,在阿留申岛弧,橄榄拉斑玄武岩已被认作是初始岩浆,它与普通高铝玄武岩有关,而后者是由积聚在莫霍面深处的橄榄石和辉石的分离作用所形成的,并代表一个新生的上地幔,更常见的浅部富铝质火山岩及深成岩可以由高铝玄武岩的壳内组分分异、岛弧地壳低熔组分的同化、地壳熔融所形成,或者是诸过程结合的产物。每个岛弧真正的地壳剖面取决于岛弧     

卡鲁溢流玄武岩由地幔羽—岩石圈混合作用形成的Re—Os同位素证据

大量证据表明大陆溢流玄武岩省与地幔羽活动有关。然而，溢流玄武岩所具有的放射性同位素特征往往超出了地幔羽源区（如海岛玄武岩所证实的）范围。这些特征较易解释为大陆岩石圈源于将温度较低的，难熔的地幔岩石圈贡献了富集同位素的（低＾１４３Ｎｄ／＾１４４Ｎｄ）物质。然而，对于将温度较低的，难熔的地幔岩石圈作为玄武质岩浆的一个重要源区的模式有不少反对意见。关于玄武岩的成因，Ｒｅ－Ｏｓ体系可以对地幔羽和大陆下岩石