Michigan, lakes

Environment Lake Michigan water treated with dispersant heavily fouled with grease and oil... 

At Mono Lake, a closed basin, alkaline, saline lake in California, the concentrations of plutonium in the water column are about two orders of magnitude higher than in Lake Michigan(12). 

In experiments where Mono Lake water was acidified to remove carbonate and bicarbonate ions and again adjusted to pH 10, more than 90 percent of the soluble plutonium moved to the sediment phase. When carbonate ion concentration was restored, the plutonium returned to solution—strong evidence of the importance of inorganic carbon to solubility in that system(13). Early studies with Lake Michigan water, which has low DOC, had also implicated bicarbonate and carbonate as stabilizing ligands for plutonium at pH 8(14). This latter research characterized the soluble species as mainly anionic in character. 

An interesting aspect of the characterization of plutonium as Pu(V) in the Irish Sea, Lake Michigan, and Pond 3513 is that the origins of the radionuclides are different in each system, i.e., fuel reprocessing waste, fallout, and laboratory effluents, respectively. 

These observations contrast with some of the results obtained in natural waters. In the experiments where contaminated sediments were equilibrated with Lake Michigan water for a number of days, the Pu(IV) that was on the sediments and was transferred to the water was oxidized to Pu(V), with the oxidation occurring either during or after desorption (15). The studies in the Irish Sea near Windscale show that although no more than 1 percent of the waste effluent stream is oxidized plutonium, approximately 5 percent of the plutonium released leaves the area in the currents of the Irish Sea as oxidized plutonium. Most of the plutonium, therefore, must be oxidized fairly rapidly in sea water. 

Observations of the ratio of oxidized plutonium to reduced plutonium may provide some insight to the observations of erratic formation and lack of equilibration in laboratory solutions at ORNL versus fairly consistent and predictable behavior in oligo-trophic lakes and marine systems. In coastal water and the relatively shallow Lake Michigan, Pu(V) is about 90 percent of the soluble plutonium, but in the upper waters of the open ocean, where it does not interact with the seafloor due to the depths,... 

Two of the study systems, Lake Michigan and Pond 3513, exhibit cyclic behavior in their concentrations of Pu(V) (Figure 2 and 3). The cycle in Lake Michigan seems to be closely coupled with the formation in the summer and dissolution in the winter of calcium carbonate and silica particles, which are related to primary production cycles in the lake(25). The experimental knowledge that both Pu(IV) and Pu(V) adsorb on calcium carbonate precipitates(20) confirms the importance of carbonate formation in the reduction of plutonium concentrations in late summer. Whether oxidation-reduction is important in this process has not been determined. 

For Pond 3513, the cycle of 2 3 8U and 239,2 °pu concentrations in water (filtered with a 0.22y membrane) is out of phase with the cycle of plutonium concentrations in Lake Michigan. In this shallow pond, the concentrations of the two actinides peak in summer and decline in winter. An explanation for this cycle of plutonium is that photosynthetic activity depletes dissolved CO2 which results in an increase in pH and this in turn shifts the oxidation state in favor of Pu(V) which is desorbed from the sediments(26). 

No profound effect of pH on K was observed for waters which ranged from pH 4 (Okeefenokee°Swamp) to pH 8 (Lake Michigan). Nor was there an effect of ionic strength on K in the samples which ranged in composition from that of the oceans to that of a lake with a conductivity of less than 20iaS/cm. 

The K1/K3 ratios divide these natural waters into three groups. Okeefenokee Swamp and Volo Bog have ratios of about 3 a group of small lakes and two coastal marine waters show a somewhat weaker binding with K1/K3 ranging from 0.16 to 0.56 Lake Michigan exhibits much weaker organic complexes with a K]VK3 of 0.03. 

Ruch, R.R. Kennedy, E.J. Shimp, N.E. Distribution of Arsenic in Unconsolidated Sediments from Southern Lake Michigan. Environ. Geol. 1979 Notes 37, 1-16. 

Shimp, N.F. Schlercher, J.S. Ruch, R.R. Heck, D.B. Leland, H.V. Trace Element and Organic Carbon Accumlation in the Most Recent Sediments of Southern Lake Michigan. Environ. Geo. 1971 Notes 41, 25. 

Late Pleistocene Lake Saline Compared with Those in Lake Michigan S Sediments. Environ. Geo. 1973 14 pp. 

Lake Ontario, early 1970s Lake Ontario, 1984/1985 Lake Michigan, 1971 Lake Michigan, 1972 Lake Michigan, 1984/1985... 

Hornbuckle KC, CW Sweeet, DL Swackhamer, SJ Eisenreich (1995) Assessing annual water-air fluxes of polychlorinated biphenyls in Lake Michigan. Environ Sci Technol 29 869-877. 

Landis MS, Vette AF, Keeler GJ. 2002. Atmospheric mercury in the Lake Michigan Basin influence of the Chicago/Gary urban area. Environ Sci Technol 36(13) 3000-3009. 

Hurley JP, Cowell SE, Shafer MM, Hughes PE. 1998. Tributary loading of mercury to Lake Michigan importance of seasonal events and phase partitioning. Sci Total Environ 213 129-137. 

A 28-year-old healthy woman seeks your advice. She is about to leave on a 7-day Caribbean cruise and is concerned about motion sickness. She recently experienced nausea and one episode of vomiting while on a sailboat on Lake Michigan for an afternoon. She is not allergic to any medications. She does not smoke and only occasionally drinks alcohol. She takes an oral contraceptive (ethinyl estradiol and norgestimate) and occasional ibuprofen for headaches. 

Lake Michigan, site 7 km from Grandhaven, Michigan, water depth 67 m (cores and sediment trap at 60 m) Alberts et al. 1989... 

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