An Initial Survey of White Dwarfs in the Sloan Digital Sky Survey

An initial assessment is made of white dwarf and hot subdwarf stars observed in the Sloan Digital Sky Survey. In a small area of sky (190 square degrees), observed much like the full survey will be, 269 white dwarfs and 56 hot subdwarfs are identified spectroscopically where only 44 white dwarfs and 5 hot subdwarfs were known previously. Most are ordinary DA (hydrogen atmosphere) and DB (helium) types. In addition, in the full survey to date, a number of WDs have been found with uncommon spectral types. Among these are blue DQ stars displaying lines of atomic carbon; red DQ stars showing molecular bands of C_2 with a wide variety of strengths; DZ stars where Ca and occasionally Mg, Na, and/or Fe lines are detected; and magnetic WDs with a wide range of magnetic field strengths in DA, DB, DQ, and (probably) DZ spectral types. Photometry alone allows identification of stars hotter than 12000 K, and the density of these stars for 15<g<20 is found to be ~2.2 deg^{-2} at Galactic latitudes 29-62 deg. Spectra are obtained for roughly half of these hot stars. The spectra show that, for 15<g<17, 40% of hot stars are WDs and the fraction of WDs rises to ~90% at g=20. The remainder are hot sdB and sdO stars.Comment: Accepted for AJ; 43 pages, including 12 figures and 5 table

Metals in the Environment: Philosophy and Action by the Metals Industry

A critical issue facing our industrial society is to determine how to continue the beneficial use of metals while minimizing adverse effects metal releases may have on people or the environment. The best way to examine potential adverse effects is to carry out risk assessments. The metals resource industry and certain federal government departments have taken a proactive approach to gaining needed information for risk assessments on metals by forming the Metals in the Environment (MITE) Research Network. This Network, receiving significant funding from NSERC for university research across Canada, is administering a 5-year integrated program defined by government and industry in a truly co-operative and integrated fashion. The program is focussing on: sources of metals, both industrial and natural; processes that move and control metal species; and impacts of metals on flora and fauna. Résumé Continuer à utiliser les métaux tout en minimisant les effers néfastes d'effluents de métaux pour les humains et l'environnement constitue l'un des principaux défis de notre société industrialisée. La meilleure approche permettant d'étudier les effets néfastes potentiels consiste à mener des études d'évaluation des risques. L'industrie des ressources métalliques avec certains ministères du gouvernement fédéral ont adopté une approche proactive dans le but d'amasser les données nécessaires aux évaluations des risques des effluents de métaux et ils ont créé le Réseau de recherche des métaux dans l'environnement (RRME). Doté d'un financement substantiel par le CRSNG, le RRME administrera un programme quinquennal pan-canadien de recherches universitaires de manière véritablement intégrée et coopérative. Ce programme porte en particulier sur les sources des métaux, naturelles ou industrielles, les processus de transport et de sélection des espèces de métaux, ainsi que l'impact des métaux sur la flore et la faune

New views on the hypothesis of respiratory cancer risk from soluble nickel exposure; and reconsideration of this risk's historical sources in nickel refineries

Abstract Introduction While epidemiological methods have grown in sophistication during the 20th century, their application in historical occupational (and environmental) health research has also led to a corresponding growth in uncertainty in the validity and reliability of the attribution of risk in the resulting studies, particularly where study periods extend back in time to the immediate postwar era (1945–70) when exposure measurements were sporadic, unsystematically collected and primitive in technique; and, more so, to the pre-WWII era (when exposure data were essentially non-existent). These uncertainties propagate with animal studies that are designed to confirm the carcinogenicity by inhalation exposure of a chemical putatively responsible for historical workplace cancers since exact exposure conditions were never well characterized. In this report, we present a weight of scientific evidence examination of the human and toxicological evidence to show that soluble nickel is not carcinogenic; and, furthermore, that the carcinogenic potencies previously assigned by regulators to sulphidic and oxidic nickel compounds for the purposes of developing occupational exposure limits have likely been overestimated. Methods Published, file and archival evidence covering the pertinent epidemiology, biostatistics, confounding factors, toxicology, industrial hygiene and exposure factors, and other risky exposures were examined to evaluate the soluble nickel carcinogenicity hypothesis; and the likely contribution of a competing workplace carcinogen (arsenic) on sulphidic and oxidic nickel risk estimates. Findings Sharp contrasts in available land area and topography, and consequent intensity of production and refinery process layouts, likely account for differences in nickel species exposures in the Kristiansand (KNR) and Port Colborne (PCNR) refineries. These differences indicate mixed sulphidic and oxidic nickel and arsenic exposures in KNR's historical electrolysis department that were previously overlooked in favour of only soluble nickel exposure; and the absence of comparable insoluble nickel exposures in PCNR's tankhouse, a finding that is consistent with the absence of respiratory cancer risk there. The most recent KNR evidence linking soluble nickel with lung cancer risk arose in a reconfiguration of KNR's historical exposures. But the resulting job exposure matrix lacks an objective, protocol-driven rationale that could provide a valid and reliable basis for analyzing the relationship of KNR lung cancer risk with any nickel species. Evidence of significant arsenic exposure during the processing step in the Clydach refinery's hydrometallurgy department in the 1902–1934 time period likely accounts for most of the elevated respiratory cancer risk observed at that time. An understanding of the mechanism for nickel carcinogenicity remains an elusive goal of toxicological research; as does its capacity to confirm the human health evidence on this subject with animal studies. Concluding remarks Epidemiological methods have failed to accurately identify the source(s) of observed lung cancer risk in at least one nickel refinery (KNR). This failure, together with the negative long-term animal inhalation studies on soluble nickel and other toxicological evidence, strongly suggest that the designation of soluble nickel as carcinogenic should be reconsidered, and that the true causes of historical lung cancer risk at certain nickel refineries lie in other exposures, including insoluble nickel compounds, arsenic, sulphuric acid mists and smoking

Respiratory cancer mortality and incidence in an updated cohort of Canadian nickel production workers

<p>Respiratory cancer mortality and incidence were examined in an updated cohort of >56,000 Canadian nickel mining and refining workers. There was little evidence to suggest increased lung cancer risk in workers who had no experience in high-risk sintering operations that were closed by 1972, apart from that which would be expected from probable increased smoking prevalence relative to the comparison population. There was no substantive evidence of increased laryngeal cancer risk in the cohort, nor was there evidence of increased pharyngeal cancer risk in nonsinter workers. Nasal cancer incidence was elevated in nonsinter workers, but excess risks appeared to be confined to those hired prior to 1960. These findings lead us to tentatively conclude that occupationally-related respiratory risks in workers hired over the past 45 years are either very low or nonexistent.</p

MANOP Site H manganese nodules and crusts chemical composition determined by atomic absorption spectrometry (AAS)

Manganese nodules and crusts were sampled from box cores collected at the Manganese Nodule Program (MANOP) site H in the Eastern Equatorial Pacific ocean. For majority of site H nodule bottoms have smooth, lustrous patches, whereas nodule tops are generally rough and dull. The top/bottom orientation of each manganese nodule was labeled during curation. Most of the nodutes studied were cut in haIf, and a 3-5 mm layer was scraped from nodule tops and bottoms. The chemical analysis was performed on both top and bottom sides as well as on the whole specimen. Atomic absorption spectrometry (AAS) was used folIowing complete dissolution with HF and aqua regia in teflon bombs

MANOP Site H manganese nodules and crusts chemical composition determined by instrumental neutron activation (INAA)

Manganese nodules and crusts were sampled from box cores collected at the Manganese Nodule Program (MANOP) site H in the Eastern Equatorial Pacific ocean. For majority of site H nodule bottoms have smooth, lustrous patches, whereas nodule tops are generally rough and dull. The top/bottom orientation of each manganese nodule was labeled during curation. Most of the nodutes studied were cut in haIf, and a 3-5 mm layer was scraped from nodule tops and bottoms. The chemical analysis was performed on both top and bottom sides as well as on the whole specimen. They were analysed at the U.S. Geological Survey, Menlo Park using instrumental neutron activation analysis with high-resolution lithium-drifted germanium detectors. This method involves the meeasurement of gamma-ray emission after proper irradiation of the samples

MANOP Sites S and R manganese nodules chemical composition determined by atomic absorption spectrometry (AAS)

Manganese nodules were sampled from box cores collected at the Manganese Nodule Program (MANOP) site S (Clarion-Clipperton Fracture Zone) and site R (Murray Fracture Zone) in the Central Pacific ocean. For these sites nodule tops are smoother than nodule bottoms, which commonly have a gritty texture. The top/bottom orientation of each manganese nodule was labeled during curation. Most of the nodutes studied were cut in haIf, and a 3-5 mm layer was scraped from nodule tops and bottoms. The chemical analysis was performed on both top and bottom sides as well as on the whole specimen. They were analysed at the U.S. Geological Survey, Menlo Park using instrumental neutron activation analysis with high-resolution lithium-drifted germanium detectors. This method involves the meeasurement of gamma-ray emission after proper irradiation of the samples