Relationships among the intensities of Li-, Be-, and Na-like resonance lines in collisionally ionized astrophysical plasmas (10(5) <= T-e <= 10(7) K)

The strongest lines emitted from optically thin collisionally ionized astro physical plasmas are usually those of the Li-, Be-, and Na-like sequences. When numerous other weaker lines are also measurable in the spectrum, the d erivation of relative element abundances is reasonably straightforward. How ever, for many sources only the strongest lines will be observed, so here w e explore under what conditions it may be possible to determine relative el ement abundances in this case. We find that several temperature regions exi st in which the ratios of these strong lines can be fairly insensitive to t emperature. We discuss applications to solar/stellar coronae, the interstel lar medium, and SN 1987A. Additionally under certain conditions in the sola r corona ratios of Li-like line intensities to those of He II are found to allow relatively straightforward determinations of the He abundance.