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Scheckel, K.G., and D.L. Sparks. 1998. Assessment of Ni sorption mechanisms on soil mineral surfaces using time-resolved x-ray absorption fine structure (XAFS) spectroscopy. V.M. Goldschmidt Conference, Toulouse, France. Mineralogical Mag. Vol., 62A:1330--1331.
Introduction: Many kinetic studies have shown that sorption of metal cations onto soil, clay mineral and metal (hydr)oxide surfaces is described by a two step process comprising a rapid stage and a slow stage (Ainsworth et al., 1994). The rapid initial stage, occurring on time scales of seconds, minutes or hours, has been interpreted as an adsorption phenomenon (Sparks, 1995). However, the slow reaction stage, associated with time scales on the order of days, weeks or months is not clearly understood. Three possible mechanisms have been attributed to the slow sorption stage including: 1)adsorption onto sites of lower reactivity (Dzombak and Morel, 1986), 2) diffusion of the adsorbate into the adsorbent via micropores and/or directly in the solid material (absorption) (Pignatello and Xing, 1995), and 3) surface precipitation formation (Scheidegger et al., 1996). However, until recently, the proposed mechanisms for slow metal sorption were based strictly on macroscopic measurements via sorption isotherms and kinetic studies. To definitively prove sorption mechanisms one must employ molecular approaches. With the advent of in-situ spectroscopic and microscopic techniques, it is possible to identify the cause of slow metal sorption mechanisms.
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Class Time Grid
Schedule blocks for Fall 2015
Courses are arranged with section letters that correspond to periods of the day. This way you will not book yourself into more than one course that meets at the same time. For example, you can only take one "A" course, and so on.
In situations where the course straddles the time blocks, the section code will begin with the letter in which the course starts.

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I recently received the following questions about animal behavior.
Q: I saw a video of a cat on a boat playing with a dolphin. Both animals seemed to be enjoying themselves. The dolphin even looked like it was smiling. Was this real or some kind of filming trickery?
A: Apparently you have never had a dolphin or a cat for a pet. A dolphin smiles perpetually, not because it thinks everything it does is funny but because that it is the way its head and mouth are shaped. When cats are not sleeping or eating they are looking for something to play with their shadow, a cardboard box, a dolphin. I found the video youre referring to online (www.youtube.com/watch?v=rynvewVe21Y), and it is as real as it gets when dolphins and cats have nothing else to do. The dolphin even looks like it is laughing. They like being filmed.
Q: My husband and I were visiting friends in Clarksville, Tenn., and saw an unusual sight: a squirrel and a rabbit playing together in the yard. I dont mean they were tossing a ball back and forth or taking turns pushing each other in a swing, but they were clearly engaged in playful behavior. The rabbit would hop and the squirrel would chase it; then the squirrel would run and the rabbit would hop after it. All four of us witnessed this one afternoon. The next day we observed the same behavior; presumably these were the same two animals we had seen before. These were definitely wild animals, not someones pets. Is playing a common behavior in wild animals?
A: I asked Jim Beasley, who does research on wildlife ecology at the Savannah River Ecology Laboratory, what he knew of wild animals playing with a different species. He knew of numerous examples, but he suspected that most of the individuals engaging in this behavior are young ones that are still playful and developing their hunting/fleeing skills. He mentioned deer and other animals playing with cats, dogs, and squirrels. He noted that such sightings of interspecies play often occur in urban or suburban areas where the landscape could have a role in modifying their behavior. The young of many mammals, such as coyotes, otters, foxes, raccoons, and deer, can be quite playful with their own species, so I am sure they would engage in similar behaviors with other species on occasion when the opportunity arose.
The excellent Animal Answer Guide series published by Johns Hopkins University Press always includes a question on whether the species in question (turtles, frogs, fishes, deer, as well as rabbits and squirrels) play. Almost no fishes, frogs, toads, or turtles have much to offer in regard to being playful creatures, even when they are young. Deer raise the bar a bit in that frogs or turtles will trigger jumping and pawing in fawns. Im pretty sure the frogs and turtles do not take advantage of the opportunity to return the playful gesture.
As for squirrels and rabbits, play behavior is widespread among all the species. Such activities are generally restricted to juveniles but may occasionally occur among adults. Behavioral ecologists assume that play in juvenile mammals confers some biological advantage to the individual as an adult, but for most species no research has been done to confirm this idea. However, in a study of ground squirrels, scientists documented that playing by juveniles enhanced the motor skills of individuals as adults, which helped them avoid predators and win in fights. Increased play among ground squirrel females leads to greater reproductive success.
Anyone who has ever had a puppy or a kitten knows that playful behavior is common among domestic dogs and cats, and it occurs frequently among other young mammals. Occasionally it even arises between two different species. Those situations are guided by each species awareness that the other does not pose a threat. A young squirrel that decided to play with a rattlesnake wouldnt be around long enough for anyone to observe the behavior.
Send environmental questions to firstname.lastname@example.com.
Whit Gibbons is an ecologist and environmental educator with the University of Georgias Savannah River Ecology Laboratory.
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