Physico-Chemical Model of Toxic Substances in the Great Lakes

Abstract

Comparison of calculated cadmium concentration under two assumptions on partition coefficient. Low load estimate............ 60. Comparison of calculated cadmium concentration under two assumptions on partition coefficient. High load estimate........... 61. (Top) Calculated load normalized cadmium time variable response (Bottom) Calculated sediment/water column partition coefficient time variable response.

Particle Transport, Nutrient Cycling, and Algal Community Structure Associated with a Major Winter-Spring Sediment Resuspension Event in Southern Lake Michigan

“…For particle-reactive constituents, internal removal through sedimentation is much more rapid than outflow. Radiotracer studies with 239 Pu (t 1/2 = 25,000 years) and 137 Cs (t 1/2 = 30.2 years) show that > 95% of these tracers were removed from the water and transferred to sediments within a few years (Wahlgren et al 1980, Thomann and DiToro 1983, Edgington and Nelsen 1986, Eadie and Robbins 1987. Although initial removal of particle-reactive tracers from the water is rapid (a few years), a small residual concentration remains in the water (either on particles, in biota, or in solution) and now diminishes exponentially on a time scale of decades.…”

“…Although initial removal of particle-reactive tracers from the water is rapid (a few years), a small residual concentration remains in the water (either on particles, in biota, or in solution) and now diminishes exponentially on a time scale of decades. Studies of Thomann and DiToro (1983), Eadie et al (1984), and Robbins and Eadie (1991) have shown that the small amount remaining in the system is primarily the result of an annual cycle of sediment resuspension and re-deposition that releases constituents from sediments back into the water. Observations of this plume event imply that this episodic process may be responsible for much of this sediment-water coupling.…”

The Lake Michigan contaminant transport and fate model, LM2-toxic: Development, overview, and application

“…Government policy makers and the scientific community continue to be interested in the development and application of integrated multicompartment water quality models that quantitatively relate sources of persistent and toxic chemicals to concentrations of these pollutants in the water, sediments, and biota of the Great Lakes (DePinto et al, 2004, DePinto et al, 1993, Thomann and Di Toro, 1983. In 1994, the Lake Michigan Mass Balance Project (LMMBP) was initiated and led by the United States Environmental Protection Agency (USEPA) Great Lakes National Program Office (GLNPO) to support the development of a Lakewide Management Plan (LaMP) for Lake Michigan.…”

“…1), a comprehensive polychlorinated biphenyl (PCB) congener-based water quality model, LM2-Toxic, was developed. In previous studies on modeling the fate and transport of PCBs in the Great Lakes region (DePinto et al, 2004, DePinto et al, 1993, Endicott 2005, Thomann and Di Toro 1983, PCBs were often simulated as either total PCB or homologs. Due to differences in both physical and chemical characteristics and concentration in various media (such as air, external load, water and sediments) among individual PCB congeners, modeling a large number of PCB congeners such as done in LM2-Toxic (54 PCB congeners) can provide both the details of the fate and transport of PCBs at the individual congener level and a more accurate assessment of total PCB dynamics in an aquatic system derived.…”

Calculation of the Ecological Risk Index in the José Antonio Alzate Dam, State of Mexico, Mexico

“…To avoid the complexity of the processes just mentioned, the partition coefficient was used [4]. The bioavailability of metals is determined by their speciation in the dissolved and particulate phases [5][6][7][8][9], and it depends on factors such as pH, dissolved oxygen, hardness, alkalinity, and the amount of suspended matter that can modify the toxicity of the chemical constituents of water [10].…”