Sediment-laden water is just water from glacial rivers that ends up in the ocean, causing the appearance (and speculation) that there are two separate oceans meeting up. Kind of like if one ocean asked another ocean to get some coffee, and then someone took a picture of it and sent the internet into a frenzy of gossip.
Gossip about oceans getting coffee aside, Bruland explained that in the summer, glacier rivers erode away the mountains and create a material known as "glacier flour" that is carried out into the water.
I know, Bill, IT'S MIND BLOWING. According to Bruland, when these glacial rivers empty into the larger body of water ”” the ocean ”” they're picked up by the water's currents. Then, they move east to west circulating, as they did in the Gulf of Alaska, creating the myth that the "oceans" never mix.
One of the major reasons why the Gulf of Alaska appears as if there are two separate oceans meeting is iron, which is found in the sediment-laden glacier water. The iron then goes to areas in the Gulf of Alaska that are deprived of the chemical.
Bruland explained that his photo shows the water from the sediment rivers pouring out and hitting the general ocean water. As for the belief that these two bodies of water will never mix? A big, resounding FALSE.
The two bodies of water are totally going to mix, although there are moments when you can look at the gulf and see the very clear gradients, as depicted in Bruland's photo. The border is never consistent, either. It will change and move with the water.