Mineralization potentials of aromatic hydrocarbons by estuarine microorganisms: variations with season, location, and bacterioplankton production

Abstract

Mineralization of 14C labeled pentachlorophenol (PCP) and 2 polycyclic aromatic hydrocarbons (PAH), naphthalene and phenanthrene, to 14C02 by surface water microorganisms was assessed in samples collected from a relatively unpolluted Long Island Sound station (USA) in midsummer and at various points in the lower Hudson Rver Estuary from September to June. PCP mineralization was always low, < 5 ng l-l d-', at both sites. Highest rates of naphthalene and phenanthrene mineralization, when corrected for volatilization during experiments, were 118 % d-' (5.8 pg 1-' d-I) and 65 % d-' (3.2 pg 1-' d-l). respectively, in Long Island Sound to 172 O/ O d-' (1.72 pg I-' d-l) and 87 % d-' (0.87 pg I-' d-') in the Hudson River Estuary. PAH mineralization and bacterio-plankton production rates, measured with [3H]thymidine incorporation, increased dramatically downstream from the northern tip of Manhattan Island to the Verrazano Narrows. Phenanthrene mineral~za-tion and bacterioplankton production rates in the Hudson were highest in summer. Bacterial cell abundance usually increased downstream and was at its highest level during June, but overall correlated poorly to bacterioplankton production and pollutant mineralization. The high rates of PAH mineralization and bacterial production near New York Harbor are probably supported by the high inputs of petroleum hydrocarbons and sewage in the region. Total bacterioplankton activity and biomass may be less important than the composition of the bacterioplankton population in determining the extent of naphthalene and phenanthrene biodegradation.