Purely academic articles aren't really what C-C is about, and 16,000 words is very long. I have a fanfiction I'm writing that's currently 12,000 words long at it's over 9 chapters!
In general, once you start getting over 2,000 words you're getting into the territory where it will be more difficult for your article to be marketable. I know it's easy to get wrapped up in your artist side-- "This is what I like to create." But you also have to put on your saleswoman hat too.
If you start getting over 2,000 words ask yourself, can I break this topic down? Are you trying to cover too much? Would your audience be more captive with an in-depth twist instead of trying to combine a general article with more specific information? Are your sentences carrying words that are just extra weight?
For example, I'm working right now on researching metabolics. I'm seeing the word thrown around in weight loss articles but it was unfamiliar. So far I've learned there are legitimate metabolic researchers out there looking at enzymes, proteins, and hormones organisms and organelles produce to metabolize food, but it's like the human genome project, there isn't a complete picture out there yet. Various universities in Europe and the United States are working on metabolic profiles, but so far all they can tell is that everyone is different. On the other hand, the word is also being used as a type of pseudo-science mumbo jumbo by diet pills claiming to control glycemic indexes, isolate proteins responsible for fat production, etc. I know from my research on dietary supplements earlier this year that the FDA is very lax in regulation, they do not approve dietary supplements, and only step in to study effects if there is a problem. Otherwise, the companies that manufacture the diet pills are expected to list all ingredients and "self-police."
This is a big topic, if I tried to write about all of it at once, it would be forever and a day long. Here is how I could break it up:
Metabolics: What's the real science behind studying metabolic rates? (talk about the university research)
The Future of Metabolics: What Are the Potential Consequences of Understanding How Humans Metabolize Food and Expend Energy (explain where the research is going, how it will not only affect health and fitness issues, but also pharmaceuticals perhaps answering questions about why medications in different dosages are effective in different people, maybe even a complete spin off on pain management medication issues and metabolism)
Junk Science: When Diet Pill Companies Want You to Believe Metabolics Are More Advanced Than They Are (covering briefly the issue with "self-policing" dietary supplement manufacturers, how research centers funded by universities are far from isolating specific causal links in metabolics and how companies are marring a future health science by wrapping it up with junk science.)
3 articles $75-$150 a piece and 800-1500 words each, probably would take me 10 hours total of writing assuming I only sold them all for $75 (my 800 piece on side effects with dietary supplements sold for $85) I would take home $135, or $13.50 an hour. Writing all of that as one large 3,000-5,000 word piece? It would be difficult to find one market for a piece covering so much ground. For example, the piece on junk science could appeal to not only scientific sites, but also weight loss sites, health and beauty sites, etc. The "research" article could be used in a variety of ways, including a continuing education site advertising careers and education in nutrition science. A "Did you find the above article interesting? Have you considered a career as a licensed nutritionist?" And so on and so on.
Does this help?