Richard Artz

Screening Level Assessment of Risks Due to Dioxin Emissions from Burning Oil from the BP Deepwater Horizon Gulf of Mexico Spill

Between April 28 and July 19 of 2010, the U.S. Coast Guard conducted in situ oil burns as one approach used for the management of oil spilled after the explosion and subsequent sinking of the BP Deepwater Horizon platform in the Gulf of Mexico. The purpose of this paper is to describe a screening level assessment of the exposures and risks posed by the dioxin emissions from these fires. Using upper estimates for the oil burn emission factor, modeled air and fish concentrations, and conservative exposure assumptions, the potential cancer risk was estimated for three scenarios: inhalation exposure to workers, inhalation exposure to residents on the mainland, and fish ingestion exposures to residents. U.S. EPAs AERMOD model was used to estimate air concentrations in the immediate vicinity of the oil burns and NOAAs HYSPLIT model was used to estimate more distant air concentrations and deposition rates. The lifetime incremental cancer risks were estimated as 6 × 10(-8) for inhalation by workers, 6 × 10(-12) for inhalation by onshore residents, and 6 × 10(-8) for fish consumption by residents. For all scenarios, the risk estimates represent upper bounds and actual risks would be expected to be less.

MercNet: a national monitoring network to assess responses to changing mercury emissions in the United States

A partnership of federal and state agencies, tribes, industry, and scientists from academic research and environmental organizations is establishing a national, policy-relevant mercury monitoring network, called MercNet, to address key questions concerning changes in anthropogenic mercury emissions and deposition, associated linkages to ecosystem effects, and recovery from mercury contamination. This network would quantify mercury in the atmosphere, land, water, and biota in terrestrial, freshwater, and coastal ecosystems to provide a national scientific capability for evaluating the benefits and effectiveness of emission controls. Program development began with two workshops, convened to establish network goals, to select key indicators for monitoring, to propose a geographic network of monitoring sites, and to design a monitoring plan. MercNet relies strongly on multi-institutional partnerships to secure the capabilities and comprehensive data that are needed to develop, calibrate, and refine predictive mercury models and to guide effective management. Ongoing collaborative efforts include the: (1) development of regional multi-media databases on mercury in the Laurentian Great Lakes, northeastern United States, and eastern Canada; (2) syntheses and reporting of these data for the scientific and policy communities; and (3) evaluation of potential monitoring sites. The MercNet approach could be applied to the development of other monitoring programs, such as emerging efforts to monitor and assess global mercury emission controls.

Comparison of the ARL/ATAD constant level and the NCAR isentropic trajectory analyses for selected case studies

Abstract The following study is a comparison of the National Center for Atmospheric Research (NCAR) isentropic trajectory model and the Air Resources Laboratories Atmospheric Transport and Dispersion (ARL/ATAD) variable height trajectory model. Back-trajectories from each model were computed within the boundary layer and at two levels above the boundary layer over periods in July and December of 1977 and February of 1978. All trajectories terminated in Charlottesville, Virginia. Assessment of the models was achieved through the study of potential vorticity measurements computed along NCAR trajectories, wind shear values computed along the ARL/ATAD trajectories, as well as through consideration of synoptic patterns available during the case study periods. A root mean square (r.m.s.) analysis was performed to quantify model differences. Results of this study show that in the absence of frontal movement the ARL/ATAD model is a better choice within the boundary layer, but only because the model is less expensive to run. NCAR trajectories are probably more realistic in the vicinity of fronts or other large sources of vertical movement. Above the boundary layer, both models produce similar trajectories when the atmosphere is barotropic; NCAR trajectories appear more accurate in baroclinic atmospheres because of better treatment of vertical motion, r.m.s. studies show that NCAR and ARL/ATAD trajectories differ more during winter than summer, especially after 48 h of trajectory calculation r.m.s. trajectory differences remain similar for different levels for a given season and period of time.

The occurrence and distribution of trace organic compounds in Bermuda precipitation

Abstract Data are presented on the chemical composition of 36 rainwater events sampled in Bermuda during 1983 and 1984. Samples were analyzed for alpha and gamma isomers of hexachlorocyclohexane, chlordaneand dieldrin. Mean concentrations with standard errors found were 854 ± 217 pg l −1 for α HCH, 126 ± 27 pg l −1 for γ HCH, 77 ±17 pg l −1 for chlordane and 158 ± 27 pg l −1 for dieldrin. The data indicate that higher concentrations of α HCH and γ HCH in rainwater are associated with air masses originating in North America. The concentrations of the compounds in precipitation are highly variable and the deposition of the compounds is extremely episodic. The wet fluxes of chlordane and dieldrin are discussed in relation to deep-sea sediment trap measurements collected at 3200 m in the Sargasso Sea 25 km southeast of the rainwater sampling site and indicate a wet flux of 78–115 ng m −2 yr −1 for chlordane and 217–237 ng m −2 yr −1 for dieldrin which is 6–8 times higher than the measured deep-sea flux.

Aerosols over the western atlantic: Scale heights, concentrations and fluxes

Abstract Aerosols were measured with two aircraft-mounted spectrometer probes from 0.1 to 23.5 μm particle radius, between 1000 and 600 mb pressure altitude (100–4300 m MSL), and up to 200 km distance off the shores of Virginia and Bermuda. The particle size distributions, typically bimodal with modes around 0.1 μm and several μm particle radius, were integrated analytically to yield mass and number concentrations. The relatively long-lived accumulation mode, of greater importance to long-range transport of S pollutants than the shorter-lived, coarse-mode aerosol fraction, showed both horizontal and vertical variabilities. Horizontally, the atmosphere was patchy in its aerosol content from tens to hundreds of km. Vertically, the accumulation-mode mass formed three atmospheric layers: A boundary layer below 900 mb that contained 10–20 μg m −3 aerosol mass, a band between 700 and 900 mb with 2–5 μg m −3 , and a layer above 700 mb that had less than 2 μgm −3 of particles. No statistically significant differences in aerosol masses between the U.S. east coast and Bermuda could be detected within the lowest and highest atmospheric layers that were investigated. Between 700 and 900mb pressure altitudes, however, the accumulation-mode mass concentration off the Virginia coast was twice than what was measured at Bermuda. In terms of fluxes, computed from the spectrometer probe-derived masses and Loran-C-measured wind velocities, it was found that 65% of the paniculate burden leaving the U.S. east coast reached Bermuda. At Bermuda, the particulate burden reaching the islands from the west was 1.6 times the fluxes of background aerosols from the south and/or the east.

NAQFC Developmental Forecast Guidance for Fine Particulate Matter (PM2.5)

AbstractThe National Air Quality Forecasting Capability (NAQFC) upgraded its modeling system that provides developmental numerical predictions of particulate matter smaller than 2.5 μm in diameter (PM2.5) in January 2015. The issuance of PM2.5 forecast guidance has become more punctual and reliable because developmental PM2.5 predictions are provided from the same system that produces operational ozone predictions on the National Centers for Environmental Prediction (NCEP) supercomputers.There were three major upgrades in January 2015: 1) incorporation of real-time intermittent sources for particles emitted from wildfires and windblown dust originating within the NAQFC domain, 2) suppression of fugitive dust emissions from snow- and/or ice-covered terrain, and 3) a shorter life cycle for organic nitrate in the gaseous-phase chemical mechanism. In May 2015 a further upgrade for emission sources was included using the U.S. Environmental Protection Agency’s (EPA) 2011 National Emission Inventory (NEI). Emiss...

Background precipitation chemistry monitoring in the Soviet Union

An overview is given of the precipitation chemistry field and laboratory programs of the former U.S.S.R. World Meteorological Organization Background Air Pollution Monitoring Program (WMO BAPMoN). Field and laboratory procedures are discussed, siting criteria are examined, station histories are documented, and four Soviet quality assurance techniques are discussed. Comparison of data from three Soviet BAPMoN stations with data from three U.S. BAPMoN stations indicate that sulfate concentrations are comparable but that U.S. samples are typically much more acidic. Soviet samples tend to have higher concentrations of cations of soil origin and higher concentrations of ammonium.

Meteorological summary of four WATOX 1985 research intensives

Abstract A detailed review of four intensive events in the Western Atlantic Ocean Experiment (WATOX) in 1985 is given. Three air parcel trajectory models are used to assess the general flow characteristics associated with these events, and results show that all three models produce trajectories with similar source regions. Not surprisingly, isentropic trajectories tended to show faster transport because of vertical movement from higher altitudes. The goal of sampling during periods of strong northwesterly flow was generally met.

A paired comparison of two precipitation chemistry sites in East-Central Mississipi

Abstract A paired comparison was performed on 2 years of precipitation chemistry data from Meridian and Newton, MS. The Meridian site is in violation of several National Atmospheric Deposition Program siting criteria, whereas the Newton site, 35 km west, is mostly in compliance. The two sites are compared through the use of volume-weighted means, deposition, logarithmic distributions, boxplots, paired t-tests, the nonparametric Wilcoxon test, and a form of linear regression analysis that accounts for cases in which both populations are subject to error. Results indicate Meridian has higher concentrations of all measured ions except NH4+. Elevated NH4+ concentrations at Newton are most likely due to the location of the site in a cattle pasture. Significant differences (95% confidence level) were found for Cl−, Na+, K+, Ca2+ and Mg2+. SO42− was found to be borderline significant.

Evaluation of precipitation chemistry siting criteria using paired stations from northern Maine and southeastern Texas

Abstract Two-year precipitation chemistry data records from each of the two paired stations are compared to determine whether the precipitation chemistry is different. In each pair, one of the stations (Caribou, Maine and Victoria, Texas) violates National Atmospheric Deposition Program (NADP) siting requirements, while the other station (Presque Isle, Maine and Beeville, Texas) is in compliance. Methods employed to carry out this study include the calculation of precipitation weighted statistics, the study of logarithmic distributions, the study of regression line residuals, the study of relative sample differences and the use of the non-parametric Wilcoxon test for two matched samples. Results indicate no clear differences occurred between paired stations over a seasonal or longer period of time; however, considerable variation was observed on a weekly basis. Maine stations were in excellent agreement for all ions; Texas stations showed small differences between ions typically associated with soil dust and between ions typically associated with anthropogenic activity.