Gaseous flux and distribution of polycyclic aromatic hydrocarbons across the air-water interface of southern Chesapeake Bay

Gaseous fluxes of polycyclic aromatic hydrocarbons (PAHs) across the air-water interface of Southern Chesapeake Bay were calculated for the period January 1994 through May 1995 using a modified two-film model. Additionally, the distributions of PAHs between the vapor and aerosol phase in the atmosphere, and between the freely dissolved and suspended particulate phase in the water column were investigated. Net instantaneous gaseous fluxes of PAHs were determined to vary in direction and magnitude both spatially and temporally across the air-water interface of Southern Chesapeake Bay at four sites ranging from remote to urban and highly industrialized. The magnitude of gas exchange fluxes was of the same order as wet and dry atmospheric depositional fluxes. Spatial variations in gaseous fluxes resulted from differences in the air-water concentration gradients between sites. Temporal variations in gas exchange fluxes resulted from seasonal changes in both water temperatures and vapor concentrations. Atmospheric PAH vapor concentrations increased exponentially with temperature at the non-rural sites suggesting volatilization from contaminated surfaces (soils, roads, vegetation) during warmer weather; whereas, PAH vapor concentrations at the rural site decreased with time. All sites experienced increased loadings of particulate-associated PAHs during winter. Mean total atmospheric PAH concentrations ranged from 7.87 ng/m&\sp3& at a rural (Haven Beach) site to 92.8 ng/m&\sp3& at an urban (Elizabeth River) site. Plots of the logarithm of the particle-vapor partitioning coefficient (C&\rm\sb{lcub}p{rcub}/TSP\sp\* C\sb{lcub}v{rcub})& versus inverse temperature indicate different particle characteristics or atmospheric partitioning processes at the urban and rural sites. Three methods (gas sparging, semipermeable membrane devices, filtration with sorption of the dissolved contaminant fraction to XAD-2 resin) for determining freely dissolved contaminant concentrations in estuarine waters were investigated. Mean total PAH concentrations in surface waters ranged from 24.2 ng/l at a mainstem bay site to 91.1 ng/l at the industrialized Elizabeth River site. Dissolved-particulate partitioning of PAHs approximated equilibrium theory at all sites and sampling periods. The results of this study support the hypothesis that gas exchange is a major transport process affecting concentrations and exposure levels of PAHs in the southern Chesapeake Bay Region

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

How New Subscribers Use Cancer-Related Online Mailing Lists

BACKGROUND: Online cancer-related support is an under-studied resource that may serve an important function in the information seeking, care, and support of cancer patients and their families. With over 9.8 million cancer survivors (defined as anyone living with cancer) in the United States alone and the number growing worldwide, it is important to understand how they seek and use online resources to obtain the information they need, when they need it, and in a form and manner appropriate to them. These are stated cancer communication goals of the US National Cancer Institute. OBJECTIVES: Our purposes are to (1) present background information about online mailing lists and electronic support groups, (2) describe the rationale and methodology for the Health eCommunities (HeC) study, and (3) present preliminary baseline data on new subscribers to cancer-related mailing lists. In particular, we describe subscribers' use of mailing lists, their reasons for using them, and their reactions to participating shortly after joining the lists. METHODS: From April to August 2004, we invited all new subscribers to 10 Association of Cancer Online Resources mailing lists to complete Web-based surveys. We analyzed baseline data from the respondents to examine their perceptions about cancer-related mailing lists and to describe how cancer patients and survivors used these lists in the period shortly after joining them. RESULTS: Cumulative email invitations were sent to 1368 new mailing list subscribers; 293 Web surveys were completed within the allotted time frame (21.4% response rate). Most respondents were over age 50 (n = 203, 72%), white (n = 286, 98%), college graduates (n = 161, 55%), and had health insurance (n = 283, 97%). About 41% (n = 116) of new subscribers reported spending 1 to 3 hours per day reading and responding to list messages. They used the mailing lists for several reasons. Among the most frequently reported, 62% (n = 179) strongly agreed they used mailing lists to obtain information on how to deal with cancer, 42% (n = 121) strongly agreed they used mailing lists for support, and 37% (n = 109) strongly agreed that they were on the mailing lists to help others. Smaller proportions of new subscribers strongly agreed that others on the mailing lists had similar cancer experiences (n = 23, 9%), that they could relate to the experiences of others on the lists (n = 66, 27%), and that others on the list gave them good ideas about how to cope with cancer (n = 66, 27%). CONCLUSIONS: Cancer-related online mailing lists appear to be an important resource, especially for information seeking but also for support of cancer survivors. These were the primary motivators most members reported for joining mailing lists. The modest proportion of subscribers who strongly agreed that they could relate to others' cancer experiences (as well as similar responses to other process questions) is undoubtedly due at least in part to the short duration that these subscribers were involved with the mailing lists. Emerging data, including our own, suggest that mailing lists are perhaps under-used by minority patients/survivors. These preliminary data add to a growing body of research on health-related online communities, of which online mailing lists are one variant