Positive ions were studied at three field sites, two of which contained ions produced by high-voltage direct current (HVCD) transmission lines. Natural ions were also studied at two of the three sites. The observed differences between natural and anthropogenic ion spectra near HVCD lines are attributed primarily to a shortening of ion lifetimes by the strong electric field associated with the HVCD lines. One exception is the production of potassium- and probably sodium-based ions from the decomposition of insects in transmission line coronas. Several ions which have been observed previously at mass 60 and 130 were also identified for the first time, using tandem mass spectrometric techniques, as trimethylamine and quinoline (and isoquinoline), respectively. ¿ American Geophysical Union 1989