Monitoring stations for this study were placed in both urban and rural areas to evaluate the influence of Baltimore's urban atmosphere on organic contaminants deposition and ammonia deposition into the Northern Chesapeake Bay. The stations, for organics, were located at Fort Mc Henry National Monument on Hart Miller Island (latitude 39° 14' north, and longitude 76°23' west) and at the U.S.G.S. Station at Still Pond (39°19' north and 76°23' west). Monitoring for ammonia deposition occurred at Solomons Island (38°17' north and 76°26' west) and the Maryland Science Center in Baltimore Maryland (39°16' north and 76°36' west).

Monitoring for organics was for simultaneous eight-hour periods collected daily for seven days in June, 1996. Atmospheric ammonia was collected every ninth day of the month from March 1997 until March 1999.

See the Related Publications section below for sources of information on the CBADS monitoring program.

Precipitation/Air Sampling and Analysis

Precipitation and air sampling occurred in a different manner for the two portions of this study. This section will present the sampling and analysis methods first for the organic contaminants, and then for the nutrient investigation.

The organic contaminant investigation employed simultaneous 8-hour high volume air samples. High volume air samples were collected using glass fiber filters to collect aerosols (organic contaminants) followed by polyurethane foam plugs. Each polyurethane foam plug was individually sealed and frozen after collection until samples were analyzed. The foam plugs were analyzed for 39 PAHs, and 71 individual PCBs were quantified using a Florsil cleanup and GC/MS and GC/ECD analysis, respectively. Results are reported as total atmospheric PAHs (S-PAH) and total atmospheric PCBs (S-PCBs). One precipitation sample was collected for this study using automated samplers that filtered the rainwater through a glass fiber filter and then extraction occurred using a column of XAD-2 resin.

The nutrient loading investigation collected samples every nine days in 1998 at the rural sample locations. Additional urban samples were collected every ninth day from March 1997 to March 1999. Samples were collected using two different methods. In March 1997, both ammonia and ammonium were collected using filter packs. These packs consisted of three 47 mm glass fiber filters coated with a 0.01 M oxalic acid solution. The oxalic acid solution was prepared using 0.12 g oxalic acid, 84 ml methanol, and 16 ml glycerol. The 24-hour samples were collected at a flow rate of 2 liters per minute. In January 1999, a honeycomb denuder/filter system was deployed along with the filter packs. This sample train consisted of the filter pack or denuder followed by a Gilmont® rotometer, Gast® air pump and an Equimeter® dry gas flow totalizer. The second system consisted of an impaction plate, followed by two honeycomb denuders, a Teflon^tm filter, and two glass fiber filters. Filter packs and the denuder/filter were prepared and extracted in a nitrogen-filled glove bag or in a laminar flow clean bench. The purpose of the denuder system was to determine the ammonia/ammonium ratio. Analytes were extracted from all filter media using dionized water and sonication. Extracted samples were frozen until samples were analyzed.

Quality Assurance (QA)

Quality assurance was performed for each portion of the study. However, details about the QA/QC process are not explicitly presented. For the organics investigation, QA/QC involved spike recovery analysis, field and laboratory blanks. Sample specific method detection limits were applied to each sample, as was blank filtering. For the nutrient investigation, field blanks were collected and analyzed to evaluate possible sample contamination. Blank correction for nutrients consisted of determining whether the sample concentration was more than three times the blank concentration. For samples whose concentrations were less than 3x blank concentration, the sample concentration was replaced with 2/3 the mean blank concentration.

Results of these studies may be found in the Report.

Related Publications/Reports

• Baker, J.E. 2000. Expansion of the Chesapeake Bay atmospheric deposition network to create an integrated nutrient-toxics deposition monitoring program. Final Report submitted to United States Environmental Protection Agency. Ref. No. 00-0199-CBL. [UMCES Technical Series No. TS-271-00-CBL].
• Leister, D.L. and J.E. Baker. 1994. Atmospheric deposition of organic contaminants to the Chesapeake Bay. Atmos. Environ., 28, 1499-1520.
• Poster, D.L., R.M. Hoff, and J.E. Baker. 1995. Measurement of particle size distributions of semivolatile organic contaminants in the atmosphere. Environ. Sci. Technol., 29, 1990-1997.
• Poster, D.L. and J.E. Baker. 1995. Mechanisms of wet deposition of organic contaminants. In: Atmospheric Deposition of Contaminants to the Great Lakes and Coastal Waters, ed. by J.E. Baker, Society of Environmental Toxicology and Chemistry, Special Publication Series. Pensacola FL.
• Poster, D.L. and J.E. Baker. 1996. Influence of submicron particles on hydrophobic organic contaminants in precipitation. 1. Concentrations and distributions of organic contaminants in rainwater. Environ. Sci. Technol., 30.
• Poster, D.L. and J.E. Baker. 1996. Influence of submicron particles on hydrophobic organic contaminants in precipitation. 2. Scavenging of polycyclic aromatic hydrocarbons by precipitation. Environ. Sci. Technol., 30.
• Scudlark, J.R., T.M. Church, and K.M. Conko. 1992. A method for the automated collection, proper handling and accurate analysis of trace metals in precipitation. In: The Deposition and Fate of Trace Metals in Our Environment, ed. by E.S. Verry and S.J. Vermette, Proceedings of the NADP Symposium, 8 October 1991, U.S. Forest Service Report No. NC-150, 57-71.
• Scudlark, J.R., K.M. Conko, and T.M. Church. 1994. Atmospheric wet deposition of trace elements to the Chesapeake Bay: CBAD year 1 results. Atmos. Environ., 28, 1487-1498.
• Wu, Z.Y., H. Han, Z.C. Lin, and J.M. Ondov. 1994. Chesapeake Bay Atmospheric Deposition Study, Year 1: Sources and dry deposition of selected elements in aerosol particles. Atmos. Environ., 28, 1471-1486.

The following Chesapeake Bay Program reports on the CBADS are available from the Maryland PPRP:

• Chesapeake Bay Atmospheric Deposition Study Final Report, Prepared by J.E. Baker and C.A. Clark for the Chesapeake Bay Program, August 1996, EPA 903-R-96-005, CBP/TRS 146/96.
• Chesapeake Bay Atmospheric Deposition Study, Phase I: July 1990 - June 1991, Appendices, Chesapeake Bay Program, March 1994, CBP/TRS 105/94. (This report includes the CBADS Quality Assurance Plan.)
• Chesapeake Bay Atmospheric Deposition Study, Phase II: July 1990 - December 1991, Appendices, Chesapeake Bay Program, July 1994, CBP/TRS 119/94.

To review the CBADNT report please go to the data page.

Go to the Chesapeake Bay Atmospheric Deposition Study Page

For more information, e-mail Dr. John Sherwell at the PPRP, or call him at 410-260-8660.