Ultraviolet Photoprocessing of Interstellar Dust Mantles as a Source of Polycyclic Aromatic Hydrocarbons and Other Conjugated Molecules

By co-depositing a gas mixture of simple carbon- and nitrogen-containing molecules with water on a 10 K surface and exposing it to ultraviolet radiation, we were able to form a residue. This residue was then placed aboard the EURECA satellite behind a magnesium fluoride window and exposed to solar radiation for 4 months before it was returned and analyzed. The resulting residue is believed to simulate the photoprocessing of organic dust mantles in the interstellar medium. Mass spectrometry indicated that the photoprocessing created a rich mixture of polycyclic aromatic hydrocarbons (PAHs) and other conjugated organic molecules, which may explain how PAHs are replenished in space.     

Biological responses to contaminants in the Humber Estuary: disentangling complex relationships

Due to the ecological importance of estuaries, it is necessary to understand the biological effects that potentially toxic contaminants induce in bioindicator species. A key aspect is whether effects at lower levels of biological organisation transfer through the system to higher levels. In understanding such processes, characterising multivariate relationships between contaminants, sediment toxicities and detoxification processes are important. Worms (Hediste diversicolor) and sediments were collected along the Humber Estuary, England, and inorganic and organic contaminants were quantified. Sediment toxicities and glutathione-S-transferases (GSTs) activity in the ragworm were analysed. Concentrations of metals were highest near urban and industrial areas, whereas organic contaminants appeared at upstream locations. GST activity correlated with heavy metals. The genotoxicity, oestrogenicity, dioxin and dioxin-like activity were higher at upstream locations. Oestrogenicity correlated with alkylphenols and some organochlorines, whilst genotoxicity correlated with organochlorines and heavy metals. Despite this, higher level biological responses could not be predicted, indicating that homeostasis is operating.     

Evidence for X-Ray Emission from a Large-Scale Filament of Galaxies?

The large-scale ( approximately 100 kpc) environments of Seyfert galaxies are not significantly different from those of non-Seyfert galaxies. In the context of the interaction model of the formation of active galactic nuclei (AGNs), it has thus been proposed that AGNs form via "minor mergers" of large disk galaxies with smaller companions. We test this hypothesis by comparing the nuclear spectra of 105 bright nearby galaxies with measurements of their R- or r-band morphological asymmetries at three successive radii. We find no significant differences between these asymmetries among the 13 Seyfert galaxies in the sample and galaxies having other nuclear spectral types (absorption, H ii region-like, LINER), nor is there strong qualitative evidence that such mergers have occurred among any of the Seyfert galaxies or LINERs. Thus, either any minor mergers began greater, similar1 Gyr ago and are essentially complete, or they did not occur at all, and AGNs form independently of any type of interaction. Support for the latter interpretation is provided by the growing evidence that supermassive black holes exist in the cores of most elliptical and early-type spiral galaxies, which in turn suggests that nuclear activity represents a normal phase in the evolution of the bulges of massive galaxies. Galaxy mergers may increase the luminosity of Seyfert nuclei to the level of QSOs, which could explain why the latter objects appear to be found in rich environments and in interacting systems.     

Sustainable impact of mussel farming in the Adriatic Sea (Mediterranean Sea): evidence from biochemical, microbial and meiofaunal indicators

We have investigated the impact of a large mussel farm on the benthic environment using a battery of benthic indicators of environmental quality (including biochemical, microbial and meiofaunal parameters). These were analysed through a multi-control sampling strategy over one year. The differences across the seasons are typically higher than those between the impacted and the control stations. No effects are seen in terms of the sediment oxygen penetration and the downward fluxes (as the total mass, organic and phytopigment fluxes). The indicators based on the biochemical compositions of the sediment organic matter and the microbial parameters also show no evidence of the eutrophication process, except as a slight increase in the bacterial density in the sediments beneath the long-lines of the farm during the period of highest mussel stocks. Finally, no effects are observed in terms of the benthic faunal indicators, as the meiofaunal abundance, the community structure and the taxa richness are all indistinguishable between the farm sediments and the controls. These results show that mussel farming in the investigated system is eco-sustainable and does not significantly alter the coastal marine ecosystem, both in terms of the functioning and the trophic state. The battery of indicators selected in this study represents a useful tool for the monitoring of the potential ecological impact of mussel farms, towards guaranteeing the sustainable development of aquacultures in shallow coastal environments.     

Space-time visualization and analysis in the Cancer Atlas Viewer

This article describes the Cancer Atlas Viewer: free, downloadable software for the exploration of United States cancer mortality data. We demonstrate the software by exploring spatio-temporal patterns in colon cancer mortality rates for African-American and white females and males in the southeastern United States over the period 1970–1995. We compare the results of two cluster statistics: the local Moran and the local G*, through time. Overall, the two statistics reach similar conclusions for most locations. Where they disagree reveals functional differences in the kinds of local spatial variation to which the statistics are sensitive and identifies some interesting patterns in the data. There are only two persistent clusters of colon cancer mortality through time, and these are clusters of low values.This project was funded by grant CA92669 from the National Cancer Institute to BioMedware, Inc. The perspectives stated in this article are those of the authors and do not necessarily represent the official views of the National Cancer Institute. Constructive criticism from Heidi Durbeck of BioMedware, Peter Rogerson of SUNY-Buffalo, and three anonymous reviewers helped us improve the interpretation and presentation of these results.     

Polychaetes as indicators of environmental disturbance on subarctic tidal flats, Iqaluit, Baffin Island, Nunavut Territory

The polychaetes of the tidal flats near the town of Iqaluit, Baffin Island were analysed along gradients of environmental disturbance resulting from human activity. Sources of environmental disturbance include a sewage lagoon, garbage sites; and an area of the tidal flat that is cleared by bulldozer. Sampling of the tidal flats included 300 biological sediment cores taken from 75 sites along seven transects. Environmental disturbance has resulted in four zones of polychaete communities with increasing distance. The heavily disturbed zone is closest to the disturbances and is devoid of polychaetes. The disturbed zone follows and is characterized by low diversity the result of increased densities of a few opportunistic species such as, Capitella 'capitata' sp. The moderately disturbed zone is characterized by increased species diversity due to organic enrichment from the disturbances. The undisturbed zone, located the furthest from the sources of disturbance, is characterized by moderate levels of diversity compared to the other three zones.     

The role of organochlorines in cancer-associated mortality in California sea lions (Zalophus californianus)

Wild California sea lions (Zalophus californianus) have an unusually high prevalence of neoplasms (18% of stranded dead adults) and high levels of contaminants. The contribution of organochlorine (OC) tissue burdens to the probability of sea lions dying from carcinoma was explored using a logistic regression model. Levels of PCBs and DDTs were determined in blubber of sea lions diagnosed with metastatic carcinoma and animals that had died from non-carcinoma-related incidents (e.g., gunshot, domoic acid poisoning). Animals with carcinoma had higher mean concentrations (based on wet weight) of PCBs and DDTs (more than 85% and 30% higher, respectively) in blubber than did sea lions without carcinoma; the highest concentrations of OCs in the sea lions affected with carcinoma were measured in the males. Blubber thickness was significantly different between the two groups of sea lions, but after controlling for this difference, there was still a significant effect of PCBs, but not DDTs, on the probability of sea lions dying with carcinoma. Age, sex, mass and length did not affect the probability of dying from carcinoma.     

加利福尼亚皮斯莫盆地（中新世低氧盆地）蒙特雷组的磷集聚速率

长期以来，海洋中的磷处于限制生长状态，因此，研究自古以来海洋中磷的集聚变化对于确定海洋古生产率模式是很重要的。我们测定了加利福尼亚谢尔海滩的磷含量和集聚速率，即富磷海相沉积岩的一个岩段，其中含有蒙特雷组普遍存在的磷质和硅质岩相。磷含量在这些岩相的主要岩性中分布很广。在磷质页岩中，重量已达到０．３６ｗｔ％～３．９ｗｔ％，与此相比，白云岩和硅质岩中只有０．０２ｗｔ％～０．４２ｗｔ％。磷集聚速率（此处记录的所有数值的单位为ｕｍｏ１Ｐｃｍ￣（－２）ａ￣（－１））随样品岩性和岩段位置的不同而表现出很大的差异。两种岩相中的磷质页岩的磷集聚速率（１．５～２９）都大大高于白云岩和硅质岩（０．１～３．１）。此外，上部硅质岩相的磷质页岩与下部磷质岩相的磷质页岩相比，前者的磷集聚速率（３．１～２９）通常高于后者（１，５～１４）。根据各岩相的线性沉积速率模式以及观察磷质页岩、白云岩和硅质岩的相对磷含量而计算出的磷平均集聚速率，在磷质和硅质岩相之间是相差不大的。这表明这两种岩相（其动物群和沉积学特征被认为反映了中中新世期间的主要海洋和气候变化）具有相似的磷埋藏量。磷的总集聚速率与其它中新世和现代成磷环境也差不多相同。我们设计了多种沉