Muscatine

"It can not only can be measured, it has been measured. "

I must say, you've never given us, here on NL, any proof of that.  Hallucinating maybe?

Would you agree it's possible to measure the quantity of nitrogen or nitrogen compounds in water?   Usually in parts per billion (ppb).

Yes. I do it nearly everyday when on projects. It's the "IOWA FACTOR", stupid! You said Iowa's fertilizer was in the gulf (keeping you on subject of YOUR assertion). How does one identify Iowa's fertilizer, miss braindead? This has been the case the whole time with your claims. Those of us in the industry cannot separate Iowa fertilizer from Nebraska fertilizer in the Gulf, nor any other state's for that matter. Iowa's fertilizer runoff from farms and lawns is not black and gold in color like the Hawkeyes. Why do you keep insisting otherwise? We know fertilizer is in the gulf. No one argues that. There can be NO proof where it came from. I have already questioned you about your agendized and location-specific ancient report you tried to pass off here. I have proven it wrong simply over the river confluence issue alone. What dingbats they were, who wrote that silly report you used, leaving out all the north and western states that also have fertilizer runoff that eventually flow into the Miss. Rvr. and then into the Gulf! So, when someone says you have never given any proof; they are right. You CANNOT prove Iowa fertilizer is in the GULF, and you are a liar to keep insisting this!

(Example: My neighbor changed his oil in his car in his garage. He took the used oil at night and walked out to the curb and dumped it into the storm sewer to get rid of it. Someone took samples where that storm drain exited into the Miss Rvr. No one can come to my neighbor and say that was his oil going into the river. They can only say oil came into the river from somewhere upstream! DUH!) Just like your fertilizer in the GULF that you have never offered any proof that it ever came from IOWA!

"Would you agree it's possible to measure the quantity of nitrogen or nitrogen compounds in water?   Usually in parts per billion (ppb)."

You don't have to obfuscate and pretend to be ignorant while trying to misdirect this thread.

Of course N can be measured.  But what you are contending is that Iowa's N in the gulf can be measured.  Of that, you have furnished no proof.