Rapid DMSP production by an Antarctic phytoplankton community exposed to natural surface irradiances in late spring

Natural marine microbial communities sourced from under fast ice at an Antarctic coastal site were incubated in tanks under differently attenuated natural sunlight for 2 wk in late spring (Expt 1) and early summer (Expt 2). In the 18 d period between the 2 sampling episodes, the ice edge retreated from 10 to within 1.5 km of the sampling site, and the fast ice began to break up. Expt 1 rapidly produced significant quantities of total DMSP (DMSPt) with concentrations increasing from 16.6 nmol l-1 to 192.7-204.5 nmol l-1 in 2 d. We believe this is the largest observed increase in DMSPt in a semi-natural community over this time frame. Abundances of Phaeocystis antarctica increased significantly during this initial period, while other phytoplankton species/groups remained stable. DMSPt concentrations then declined at rates averaging 39.2-50.0 nmol l-1 d-1 between Days 2 and 4. No major DMSPt production event occurred during Expt 2 despite strong community similarities. Sea ice breakout exposes phytoplankton to significant light-related oxidative stress, and these results suggest the rapid production of DMSPt during Expt 1 was due to the initiation of anti-oxidant mechanisms by a low-light-acclimated community in response to solar radiation stress. DMS concentrations remained comparatively low throughout Expt 1, suggesting oxidation of DMSP to products other than DMS. Rapid sea ice breakout in coastal regions of Antarctica may result in similar fast DMSP production events during spring

Geo-demographics of gunshot wound injuries in Miami-Dade county, 2002–2012

Abstract Background We evaluated correlates of gunshot wound (GSW) injuries in Miami-Dade County, Florida. Firearm-related injury has previously been linked to socio- and geo-demographic indicators such as occupation, income, neighborhood and race in other metropolitan areas, but remains understudied in Miami. Methods We reviewed 4,547 cases from a Level I trauma center’s patient registry involving an intentional firearm-related injury occurring from 2002 to 2012. During this eleven-year study period, this trauma center was the only one in Miami-Dade County, and thus representative of countywide injuries. Results The crude morbidity rate of GSW injury over the 11-year period was 15 per 100,000 persons with a crude mortality rate of 0.27 per 100,000 persons. The case fatality rate of injured patients was 15.4%. Both morbidity and mortality increased modestly over the 11-year study period. The total number of GSW patients rose annually during the study period and patients were disproportionately young, black males, though we observed higher severity of injury in white populations. Geo-demographic analysis revealed that both GSW incident locations and patient home addresses are spatially clustered in predominantly poor, black neighborhoods near downtown Miami, and that these patterns persisted throughout the study period. Using spatial regression, we observed that census tract-level GSW incidence rates (coded by home address) were associated with a census tract’s proportion of black residents (P < .001), single-parent households (P < .001), and median age (P < .001) (R 2 = .42). Conclusions These findings represent the first representative geo-demographic analysis of GSW injuries in Miami-Dade County, and offer evidence to support urgent, targeted community engagement and prevention strategies to reduce local firearm violence

Global oceanic DMS data inter-comparability

The global surface seawater dimethylsulphide (DMS) database (http://saga. pmel. noaa. gov/dms/) contains >50,000 data points and is the second largest trace gas database after carbon dioxide. However, there has been relatively little quality control on the data that have been collated to date. Furthermore, the recent development of technologies capable of high frequency (>1 Hz) DMS measurements will have a disproportionate effect on the database in future years. At this juncture, the comparability of analytical techniques, sample handling methodologies and standards are pressing issues that the DMS community needs to address. In October 2010, during the Fifth International Symposium on Biological and Environmental Chemistry of DMS(P) and Related Compounds held in Goa, India, attendees participated in a discussion concerning the current DMS database and its future development. We develop some of the ideas from that session and combine them with available data. From the few inter-comparison exercises that have been conducted we show that variability between existing measurements within the DMS database is likely to be ≤25%. Tests comparing different DMSP·HCl standards demonstrate that a reference calibration standard would be beneficial for the DMS community. Confidence in future data collation would be substantially improved with a comprehensive inter-comparison experiment between new analytical techniques and sampling methodologies (e. g., mass spectrometers with equilibrators attached to a continuous flow of seawater) and more established methods (i. e., filtered samples analysed with purge and trap gas chromatography). We conclude with recommendations for the future expansion of the DMS database and its data quality control. © 2011 Springer Science+Business Media B.V