Margie Springer-Young

Evidence of inorganic chlorine gases other than hydrogen chloride in marine surface air

We report the first measurements of inorganic chlorine gases in the marine atmosphere using a new tandem mist chamber method. Surface air was sampled during four days including one diel cycle in January, 1992, at Virginia Key, Florida. Concentrations of HCl* (including HCl, ClNO3, ClNO2, and NOCl) were in the range 40 to 268 pptv and concentrations of Cl2* (including Cl2 and any HOCl not trapped in the acidic mist chamber) were in the range <26 to 254 pptv Cl. Concentrations of Cl2* increased during the night, and decreased after sunrise as HCl* concentrations increased by similar amounts. The measurements suggest an unknown source of either HOCl or Cl2 to the marine atmosphere. Photochemical model calculations indicate that photolysis of the observed Cl2* would yield a chlorine atom (Cl•) concentration of order 104–105 cm−3. Oxidation by Cl• would then represent a significant sink for alkanes and dimethylsulfide (DMS) in the marine boundary layer. The cycling of Cl• could provide either a source or a sink for O3, depending on NOX levels.

On the ozone minimum over the equatorial Pacific Ocean

Since 1977, several ship and aircraft expeditions to the equatorial Pacific have reported extremely low (≤10 ppbv) or undetectable levels of ozone within the marine boundary layer. Of necessity, field programs from mobile platforms are limited in both their temporal and spatial coverage. However, a 10-year record of observations at the geophysical monitoring for climatic change site in American Samoa suggests that low ozone mixing ratios are a common occurrence and may reflect a spatially variable but permanent region of low ozone in the equatorial Pacific. The spatial and temporal limits of this feature as well as some aspects of the intensity of the minimum appear to be maintained by the large-scale atmospheric circulations of the equatorial Pacific. Perturbations in the large-scale circulations as well as episodic events are reflected in observations of O3 in the equatorial Pacific. Variations in the large-scale, zonal circulation patterns (i.e., Walker circulation) of the equatorial Pacific appear to have a major influence on the spatial distribution of O3 across the equatorial Pacific. The relative importance of variations in large-scale, meridional circulation patterns on the distribution of O3 in the tropical Pacific is uncertain; however, they may be important at latitudes somewhat removed from the equator such as at American Samoa.

Nitrogen oxides and ozone production in the North Atlantic marine boundary layer

Measurements of reactive nitrogen gases (NO, NO2, NOy), as well as related chemical (O3, CO, aerosol black carbon, radon, selected nonmethane hydrocarbons) and meteorological parameters were made on board the R/V Malcolm Baldridge prior to and subsequent to the 1992 ASTEX (Atlantic Stratocumulus Transition Experiment) in the North Atlantic Ocean during June and July 1992. Results showed indications of well-defined plumes from North America and Europe from both chemistry and back trajectory data. Elevated ozone concentrations were also observed in airmasses from uninhabited continental regions. Chemical and meteorological data were incorporated into a simple photochemical model in which ozone destruction predominated over

Hydrogen peroxide in the marine atmospheric boundary layer during the Atlantic Stratocumulus Transition Experiment/Marine Aerosol and Gas Exchange experiment in the eastern subtropical North Atlantic

Gas phase H2O2 was measured in surface air on the NOAA ship Malcolm Baldrige from June 8 to 27, 1992 (Julian days 160–179), during the Atlantic Stratocumulus Transition Experiment/Marine Aerosol and Gas Exchange experiment in the eastern subtropical North Atlantic region. Average H2O2 mixing ratios observed were 0.63±0.28 ppbv, ranging between detection limit and 1.5 ppbv. For the entire experiment, only weak or no correlation was found between H2O2 mixing ratio and meteorological parameters (pressure, temperature, humidity, or UV radiation flux) as well as with tracers of continental air masses (CO, black carbon, radon). The average daily H2O2 cycle for the entire period exhibits a maximum of 0.8±0.3 ppbv near sunset and a minimum of 0.4±0.2 ppbv 4–5 hours after sunrise. Several clear H2O2 diurnal variations have been observed, from which a first-order removal rate of about 1×10−5 s−1 for H2O2 can be inferred from nighttime measurements. This rate compares well with those deduced from measurements taken at Cape Grim (Tasmania, 41°S) and during the Soviet-American Gas and Aerosol III experiment (equatorial Pacific Ocean).

Carbon monoxide gradients in the marine boundary layer of the North Atlantic Ocean

We present an observational data set that suggests that the ocean source of carbon monoxide (CO) may influence the atmospheric CO concentration in the marine boundary layer (MBL). Atmospheric CO concentration gradient data obtained during the 1992 Atlantic Stratocumulus Transition Experiment Marine Aerosol and Gas Exchange (ASTEX/MAGE) show significantly (range of 2-47 ppbv, average of 15 ppbv) more CO at altitudes of 0.05 to 0.5 m above sea level as compared to 10 m above sea level. The seawater CO concentrations needed to support the fluxes obtained from an atmospheric gradient calculation are much higher than generally reported in the literature. However, studies of CO production by Jones and Amador (1993) and data from Seiler (1978) suggest the possibility that CO production and the resultant flux to the MBL could be 1-2 orders of magnitude higher than currently estimated using seawater pumped from depths of 4-10 m below the sea-air interface. We infer that the surface ocean production and sea-air exchange of photochemically produced trace gases such as CO may participate in physical, chemical and biological processes on vastly different spatial and temporal scales than those inherent to more stable species such as CO 2 .

Impact of an episodic event on copper and zinc concentrations and speciation in surface waters of the Gulf of Mexico

Abstract Electrochemical and chelation/extraction trace metal techniques are used to develop an understanding of changes in copper and zinc concentrations and speciation associated with a hydrographic and atmospheric event which occurred during an 8-day station in the Gulf of Mexico. Changes in copper and zinc concentrations and speciation coincided with physical changes and biological productivity stimulation. In normally oligotrophic water masses it is possible that episodic events, such as inputs from beneath the mixed layer or aeolian transport, may impact the interaction of trace metals and marine biological processes.