Dissolved Hydrocarbons and Related Microflora in a Fjordal Seaport: Sources, Sinks, Concentrations, and Kinetics

Abstract

The continuous addition of toluene as a solute of treated ballast water from oil tankers into a well-defined estuary facilitated the study of the dynamics of dissolved hydrocarbon metabolism in seawater. Most rates of toluene oxidation were in the range of 1 to 30 pg/liter per h at 0.5,g of toluene per liter. Near the ballast water injection point, a layer of warm ballast water, rich in bacteria, that was trapped below the less-dense fresh surface water was located. Toluene residence times were approximately 2 weeks in this layer, 2 years elsewhere in Port Valdez, and 2 decades in the surface water of a more oceanic receiving estuary adjacent. Mixing was adequate for a steady-state treatment which showed that 98% of the toluene was flushed from Port Valdez before metabolism and gave a steady-state concentration of 0.18 jig/liter. Total bacterial biomass from direct counts and organism size data was usually near 0.1 mg/liter, but ranged up to 0.8 mg/liter in the bacteria-rich layer. The origin of bacteria in this layer was traced to growth in oil tanker ballast during shipments. The biomass of toluene oxidizers in water samples was estimated from the average affinity of pure-culture isolates for toluene (28 liters per g of cells per h) and observed toluene oxidation kinetics. Values ranged from nearly all of the total bacterial biomass within the bacteria-rich layer down to 0.2% at points far removed. Because the population of toluene oxidizers was large with respect to the amount of toluene consumed and because water from a nearby nonpolluted estuary was equally active in facilitating toluene metabolism, we searched for an additional hydrocarbon source. It was found that terpenes could be washed from spruce trees by simulated rainfall, which suggested that riparian conifers provide an additional and significant hydrocarbon source to seawater.

Nutrient Uptake by Microorganisms according to Kinetic Parameters from Theory as Related to Cytoarchitecture

“…However, some workers suggest that such substrates may be transported ac- a Conversion factors used: 400 mg/liter (wet wt) OD Ϫ1 (30), 3 mg of cells (wet wt) (mg dry wt) Ϫ1 , 1.9 mg of cells (dry wt) mg of protein Ϫ1 . b Biomass is taken as 53% of the total population which used leucine, as determined by autoradiography, and corrected for the 0.8-g-liter Ϫ1 ambient leucine present (12).…”

Competition in chemostat culture between Pseudomonas strains that use different pathways for the degradation of toluene

“…In environments that are adapted .y of uptake. Therefore, we assume, in pursuit of to low concentrations of toluene, such as raw seawater, Monod 5, 6) stated in general for nonpolar compounds, constants for toluene uptake as low as 5 nM were found (7). controlling enzyme of the degradation pathway Groundwater bacteria were found to degrade toluene to a ie specific affinity (the slope of the p. versus s concentration below 12 nM (2).…”

Interactions between marine bacteria and dissolved-phase and beached hydrocarbons after the Exxon Valdez oil spill

“…We had previously examined hydrocarbon oxidizer populations (9), oxidation rates (10), and concentrations in the region (see below) in a search for terpene hydrocarbons. These were located (8), as predicted from kinetics of toluene (12) and terpene (5) oxidation, and presumably arose from coastal conifers and moved into the region with the current. We therefore examined the microflora downstream from Bligh Island in anticipation of a similar response.…”