Experiments were carried out in diluted seawater media at different salinities (4-29%o) and different concentrations of the chelator NTA (nitrilotriacetic acid) to determine the relationship between the chemical speciation of cadmium and the toxicity of cadmium to Palaemonetes pugio, grass shrimp. After four days of exposure to a given concentration of CdCl2, shrimp mortality decreased with increasing salinity and increasing concentration of NTA. The protective effect of high salinity or NTA was attributable to the complexation of cadmium. Mortality was related to the measured free cadmium ion concentration that, in turn, was determined by the total concentration of cadmium and by the level of complexation by either chloride ion or NTA. Fifty percent mortality occurred at a free cadmium ion concentration of ~4 X 10-7 M.

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We recently demonstrated that zinc, copper, and hemocyanin metabolism in the blue crab varies as a function of the molt cycle. To extend these observations, and better delineate metal metabolism in marine crustaceans, we have conducted experiments to determine if environmental temperature and season of the year affect concentrations of hemocyanin and copper in the hemolymph and copper and zinc in the digestive gland. Overwintering, cold water crabs (6°C) had decreased hemocyanin and copper in the hemolymph and normal zinc and copper in the digestive gland with respect to summer crabs collected at 20-30°C. When these crabs were warmed to 20°C and fed fish for three weeks, they showed increases in the concentrations of copper in the digestive gland, and copper and hemocyanin in the hemolymph. In addition, a change from a zinc to a copper-dominated metallothionein was found in a majority of the warmed crabs, suggesting the involvement of copper metallothionein in the resynthesis of hemocyanin. Based on these observations and previous data (Engel, 1987) a conceptual model of copper and zinc partitioning in the blue crab has been constructed. In this model, metallothionein has an important role in metal regulation both during molting and in the changes related to season of the year. Metallothionein-bound copper and zinc appear to be regulated at the cellular level for the synthesis of metalloproteins, such as hemocyanin (copper) and carbonic anhydrase (zinc), both of which are necessary for normal growth and survival. Finally, we present evidence showing that copper metallothionein can directly transfer its metal to the active site of apohemocyanin. Copper insertion seems to precede the formation of viable oxygen binding sites.

Blue crab, Callinectes sapidus, hemolymph and digestive glands were examined at different stages of the molt cycle to determine whether molting affected tissue and cytosolic partitioning of copper and zinc and, if so, whether metallothionein was involved. The crabs used in these determinations were not exposed to elevated concentrations of copper or zinc. Concentrations of hemocyanin, copper, and zinc in the hemolymph all decreased significantly during molt. They were lowest at the soft crab stage (A 2 ) and highest during premolt (D!-D 3 ) and intermolt (C 4 ). The digestive gland copper concentrations also were highest during premolt (D!-D 3 ) and lowest in the papershell stage (BO. Zinc followed the same general pattern in both hemolymph and digestive glands. The cytosolic distributions of copper and zinc were determined in the digestive glands using gel filtration chromotography. The elution profiles showed that the percentages of copper and zinc on metallothionein ranged from 10% copper/ 90% zinc at DI to 100% copper at B, . The estimated concentrations of metallothionein were highest during intermolt (Ci) and premolt (D!-D 3 ) and lowest during the papershell (B,). The observed changes in the tissue and cytosolic partitioning of copper and zinc are consistent with the physiological changes occurring in the crabs. These observations support the hypothesis that metallothioneins are naturally occurring proteins that are actively involved in the synthesis of hemocyanin and zinc regulation during the normal processes of growth in blue crabs.

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Advanced multiscale modeling and simulation have the potential to dramatically reduce the time and cost to develop new carbon capture technologies. The Carbon Capture Simulation Initiative is a partnership among national laboratories, industry, and universities that is developing, demonstrating, and deploying a suite of such tools, including basic data submodels, steady-state and dynamic process models, process optimization and uncertainty quantification tools, an advanced dynamic process control framework, high-resolution filtered computational-fluid-dynamics (CFD) submodels, validated high-fidelity device-scale CFD models with quantified uncertainty, and a risk-analysis framework. These tools and models enable basic data submodels, including thermodynamics and kinetics, to be used within detailed process models to synthesize and optimize a process. The resulting process informs the development of process control systems and more detailed simulations of potential equipment to improve the design and reduce scale-up risk. Quantification and propagation of uncertainty across scales is an essential part of these tools and models.

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