Bulk atmospheric deposition of hydrocarbons to lower Chesapeake Bay

Abstract

Anthropogenic and biogenic hydrocarbons (HC) were continuously deposited from the atmosphere at stations in SE Virginia. The bulk deposition rate for total unresolved complex mixture (UCM) and n-alkane HC was constant at all stations during the sampling period (> 1 year). The deposition rates at the three non-urban stations was similar and averaged 69, 27 and 18 μg m −2 d −1 for total, UCM and n-alkane HC, respectively. The urban station had a higher deposition rate for total (203 μg m −2 d −1) and UCM (90 μg m −2 d −1) HC than the non-urban stations, but a similar deposition rate for n-alkanes (22 μg m −2d −1). These results indicate a regionally similar deposition rate for biogenic ( n-alkanes) and anthropogenic (UCM) HC, with a major localized input of anthropogenic HC at the urban station. Long range atmospheric transport followed by dry deposition appear to be the major processes responsible for these similar deposition rates over this geographical area.