Russell A. Moll

Concentrations of Dissolved and Particulate Polychlorinated Biphenyls in Water from the Saginaw River, Michigan

The Saginaw River receives water from a major drainage basin in the east-central portion of the lower peninsula of Michigan. Historically the river has been contaminated with polychlorinated biphenyls (PCBs) from several sources. The present study was conducted to determine the concentrations of PCBs in both the dissolved and particulate phases of water in the lower Saginaw River, as well as the relative contribution of PCBs from the lower portion of the river relative to more upstream locations. Water samples were collected in 1990–1991, during a range of discharge conditions. Suspended particulates were collected from water onto glass-fiber filters by use of a “Penta-plate” filtration apparatus. Filtered water was subsequently passed through XAD-2 macroreticular resin to collect the “dissolved” PCBs. Concentrations of PCBs in both phases were determined by congener specific gas chromatography with electron capture detection. Total concentrations of PCBs ranged from 11 to 31 ng/L. The concentrations of PCBs in the dissolved phase ranged from 1.9 to 16 ng/L. The ratio of total PCBs bound to suspended particulates, relative to dissolved PCBs, was 2:1 and remained fairly constant for discharges less than approximately 400 M3/sec. The loading of total PCBs to Saginaw Bay was estimated to be 225 kg/yr, of which approximately 60% was found to be contributed by the lower 8 km of the Saginaw River.

Assessing the Potential Efficacy of Glutaraldehyde for Biocide Treatment of Un-ballasted Transoceanic Vessels

Treating the ballast water of oceanic vessels with a biocide is one potential management strategy to reduce the number of nonindigenous species released into the Laurentian Great Lakes from NOBOB (no ballast on board) vessels. To evaluate biocide effectiveness, glutaraldehyde, a five-carbon dialdehyde widely used for its antimicrobial properties, was investigated. Biocide effectiveness was assessed for various organisms using 24 h acute toxicity bioassays in water-only and water-sediment environments. Acute studies indicate a 24 h LC90 value of 100 mg glutaraldehyde L–1 or less for most of the freshwater organisms tested. The main exception was the freshwater amphipod, Hyalella azteca, which was much more resistant to glutaraldehyde (24 h LC90 = 550 mg glutaraldehyde L−1; 95% CI: 476–681). Biocide efficacy was also evaluated in water-sediment exposures. The presence of a test sediment (3% organic carbon) greatly increased lethal concentration estimates for the oligochaete Lumbriculus variegatus, but not for H. azteca: The 24 h LC90 for L. variegatus varied depending on the water-sediment ratio, and ranged from 61 mg glutaraldehyde L−1 (95% CI 52–78) for an 8:1 water-sediment ratio to 356 mg glutaraldehyde L−1 (95% CI 322–423) for a 2:1 water-sediment ratio. This indicates that the amount of sediments present in NOBOB vessels may have a significant impact on biocide efficacy. Experiments using material from actual NOBOB vessels generally corroborated data from the water-sediment experiments and suggest a potential treatment concentration of approximately 500 mg glutaraldehyde L−1 for short exposure periods (e.g., 24 h).

Abundance and distribution of bacterioplankton in the Gambia River, West Africa

Four ecological zones of the Gambia River were sampled during four different hydrologic seasons for determination of microbial, nutrient, and physical parameters. A Greco-Latin Square experimental design was used to define the particular transect, station, depth, and tide/time-of-day of samples taken. Ranges of total bacterioplankton densities (106 cells/ml) were similar to those of tropical and temperate environments. Numbers of free bacteria were similar temporally, whereas attached bacteria numbers were greater during periods of high stream flows when suspended solids concentrations were higher. Free bacteria were usually twice as numerous in the freshwater zones than in the estuarine zones. Attached bacterial densities were approximately four times greater in the estuarine zones than in the freshwater zones. Uptake of3H-glucose on both a sample volume and per-cell basis increased from the early stages of the flood (6.95±SE 1.37 ng/liter/hour and 3.8 pg/hour/106 cells, respectively) and reached observed annual maximums during the dry season (21.01±SE 3.05 ng/ liter/hour and 13.0 pg/hour/106 cells, respectively). Spatially,3H-glucose uptake per sample volume and per cell was highest in the upper river zone and lowest in the lower estuary zone. The lower estuary zone consistently acted out of concert with the other river zones in terms of3H-glucose and14C-bicarbonate uptake. Analysis of variance (ANOVA) indicated that free and attached bacterioplankton densities were not homogeneous among transects, stations, depths, and tide/time-of-day at the different zones during the four hydrologic seasons. The results suggested that heterotrophy overshadowed autotrophy in the river and that the bacterial abundance, distribution, and glucose uptake activity in this tropical floodplain river were greatly influenced by the annual flood and the presence of extensive mangrove forests in the estuary.

Movement and Loadings of Inorganic Contaminants Through the Lower Saginaw River

Abstract The objective of this study was to investigate the movement of selected contaminants (four heavy metals) and conventional limnological variables through the lower Saginaw River. We related limnological variables to concentrations of contaminants, determined if sources of these contaminants existed in the lower 8 km of the river, and calculated loadings of materials to Saginaw Bay. Concentrations of most variables changed significantly among the six sampling dates in 1990–1991, while relatively few variables were different among the six sampling stations. Causes of changes in concentrations of variables in the river over time appeared to stem from two factors, seasonality and river discharge. One phase of the sampling program was conducted on six different dates which encompassed river flows ranging from greater than 700 m 3 sec −1 to less than 25 m 3 sec −1 . The date on which the least river discharge was observed included a flow reversal when Saginaw Bay water intruded into the lower Saginaw River. Statistical analyses showed that temporal variation among variables was due, in part, to fluctuating river discharge and in part to seasonal factors. The relative importance of these two components varied among parameters. For example, total suspended solids were positively correlated with river discharge, while chlorophyll varied more seasonally. In contrast to temporal trends, few parameters varied significantly among the six sampling stations. This was especially true for dissolved and paniculate metals. Loadings of key materials to Saginaw Bay from the Saginaw River were generally positively correlated with river discharge. We concluded that most substances entered the river upstream of our study section in the lower 8 km of the Saginaw River.

In Situ Quantum Efficiency of Lake Superior Phytoplankton

In situ quantum efficiencies were measured in Lake Superior over a 4-day period in 1978 and on one occasion in 1980. In 1980, experimental artifacts caused by exposing deep phytoplankton to elevated irradiances were minimized by the use of SCUBA divers. The trends of quantum efficiency with depth agreed well with theory. In the nutrient-limited upper portion of the euphotic zone, quantum efficiencies increased with depth, whereas in the light-limited lower portion of the euphotic zone, quantum efficiencies were relatively constant. Maximum quantum efficiencies calculated with downwelling irradiances ranged from 0.041 to 0.069 moles C fixed • Einst abs−1 with a mean maximum quantum efficiency of 0.0538 ± 0.0025 moles C fixed • Einst abs−1. Maximum quantum efficiencies in morning experiments ranged from 0.041 to 0.053 moles C fixed • Einst abs−1 and were slightly less than noon values, 0.057 to 0.067 moles C fixed • Einst abs−1. Correction for scalar irradiance would reduce all quantum efficiencies by 25%.

Distribution of Water Masses in and Near the Straits of Mackinac

Abstract Three cruises in the Straits of Mackinac area were conducted from 30 August to 8 October 1973. Samples were taken from up to 11 depths during each cruise and analyzed for silica, nitrate, total and soluble phosphorus, chlorophyll a , pH, water temperature, and specific conductance. Cluster analyses were used to visualize the relationship between stations for each depth on all cruises. The clearest relationships observed were from 0, 5, and 10 m depths, while clusters of data from other depths were not as useful in describing water masses. Analyses of 0 - 10 m depths showed a consistent homogeneous water mass extending through the northern edge of the Straits proper, past the western edge of Mackinac Island, to south of Bois Blanc Island. This cluster of stations was found during most wind conditions at the three depths considered. The last cruise, 6-8 October, occurred during a period of light winds from the southeast which partially disrupted this cluster. Relationships between the variables were defined by factor analysis which showed silica and nitrate increased with decreasing water temperature and pH, and partly as a function of depth. Secchi disc values tended to vary independently of most other variables, implying these readings had little value in explaining water quality in the Straits region.

Response of bacteria and phytoplankton to contaminated sediments from Trenton Channel, Detroit River

Several types of bioassays were used in 1986 and 1987 to investigate the effect of contaminated sediments on natural populations of bacteria and phytoplankton from the Trenton Channel, Detroit River. The approach included the measurement of uptake of 3H-glucose or 3H-adenine by bacteria and 14C-bicarbonate by phytoplankton in the presence of different amounts of Trenton Channel and Lake Michigan (control) sediments. Trenton Channel sediments are contaminated by high levels of toxic organic compounds and metals, especially zinc, lead, and copper. Because levels of biomass of bacteria and phytoplankton varied widely among the different bioassays, it was necessary to adjust uptake rates for biomass. Biomass adjustments were made using acridine orange counts for bacteria and chlorophyll measurements for phytoplankton. The results show a statistically significant suppression of uptake of substrates for both bacteria and phytoplankton with increasing amounts of sediment. Uptake was suppressed as much as 90 percent for bacteria and 93 percent for phytoplankton at 1200 mg l-1 of Trenton Channel sediments compared to bioassays without sediment. Uncontaminated Lake Michigan sediment suppressed uptake much less than Detroit River sediment; the difference in suppression of uptake between the two types of sediment was statistically significant for both bacteria and phytoplankton.

Analysis of temporal and spatial phytoplankton variability in a Long Island salt marsh

A study of phytoplankton and related variables in a Long Island salt marsh was designed to incorporate three major sources of variation in the sampling regime: spatial, short-term temporal, and long-term temporal. The combination of multivariate (MANOVA and factor analysis) and univariate (ANOVA) data analyses was used to examine the relative importance of each source of variation in 11 variables and to aid in the ecological interpretation of the data. MANOVA confirmed that all three sources of variation were significant with temporal variation (weekly sampling and at different times of the day) more important than spatial variation (sampling at different stations). The analyses also indicated that sampling a dynamic, tidally-driven system, such as a small salt marsh, cannot be carried out on a once-per-day basis; tidal flushing and diurnal changes in primary production induce a large amount of variation into the concentrations of phytoplankton and related variables within the salt marsh.