I have used river drift wood for well over a decade and have never had any issues. I've got wood right now that I pulled out of the Wynoochee reservoir. All the talk of conifers poisoning the water - it's amazing we have any fish in our local lakes and streams.
It looks like the article linked above was written by someone in Poland and is specific to species of tress found there. He mentions near the bottom that coniferous firs don't contain resin but doesn't mention any actual species. Most of what I find and use is from Douglas Fir (which isn't even a true fir). I have also used Alder and maple.
My only caveat being that the wood I use has been submerged for years and already sinks - I would not use fresh cut wood.
The photo above looks to be a softer wood, and I would expect it to take a very long time to sink.
