WEATHER
The weather so far this trip has been much, much nicer than during MAG-Mix1. We have moderate breezes, sunny skies, and the seas are not nearly as rough as our first cruise in May. The mornings and evenings have been a little chilly but perfect during the middle of the day.
SCIENCE
The sampling has been almost nonstop. Last 
night (10/31/08) we sampled the change in salinity from open water in the Gulf of Mexico to freshwater in the Mississippi River. During MAG-Mix1, the Mississippi River had high discharge so we didn't have to travel very far upriver to reach freshwater. However, during this trip we had to go all the way to Venice, LA, and still didn't reach truly freshwater (0 PPT). During high river discharge like we had in May, the freshwater can push the salt water all the way out of the river, but when the river flow slows, the salt water comes back in.
night (10/31/08) we sampled the change in salinity from open water in the Gulf of Mexico to freshwater in the Mississippi River. During MAG-Mix1, the Mississippi River had high discharge so we didn't have to travel very far upriver to reach freshwater. However, during this trip we had to go all the way to Venice, LA, and still didn't reach truly freshwater (0 PPT). During high river discharge like we had in May, the freshwater can push the salt water all the way out of the river, but when the river flow slows, the salt water comes back in.Near Venice, LA, we collected extra water from the lowest salinity water we sampled. This water will be used in a series of mixing experiments later in the cruise. A lot of our measurements look at what is dissolved in the water, but we have to remember that the river also carries a lot of sediment, and when the river water mixes with the salt water, a lot of chemicals wash off of the sediments, which increases their concencentrations in the river water.
Other things can be changing the chemical concentrations at the same time, so we like to perform a mixing experiment to determine how much of the change comes from just this mixing process, and how much comes from other processes. A few of the other things which might change the chemical concentrations are 1) organisms could be using the chemicals when they grow, or releasing them when they di
e; 2) chemicals could be coming in from other sources, like ground water; 3) chemicals may be being removed from the water as the sediment clumps together and settles out.
e; 2) chemicals could be coming in from other sources, like ground water; 3) chemicals may be being removed from the water as the sediment clumps together and settles out.Science Party:
It seems like everyone on the boat is in good spirits this trip. With the modest sea conditions, no one has really been suffering from the mal de mer. at least not as much as during MAG-Mix 1. Also, we started off on a bit of a holiday, so the mood has been very light-hearted as people occasionally popped up on deck in costume. 
No comments:
Post a Comment