This paper describes adsorption of the aqueous purines adenine (10), adenosine (11), adenosine 5’-monophosphate (12), guanosine (13), and guanosine 5’-monophosphate (14) on compost-derived humic acid (HA) over the solute concentration (12-1200 mu M) and temperature (10.0-40.0 degrees C) ranges used with pyrimidine solutes in Part 1. Nucleobase 10 and nucleosides 11 and 13 are neutral under the experimental conditions, while nucleotides 12 and 14 are monoanions. All the purines interact with HA, but only adenine causes HA dissolution at pH 5-6 and temperatures above 25.0 degrees C, as found with cytosine and (-)nicotine. The TR spectrum of the soluble adenine-HA product indicates strong interaction with carboxylic and phenolic HA groups that is not due to simple proton transfer. Pyrimidines and purines are adsorbed in sequence on three HA sites A, B, and C. Most of the data fit the Langmuir model to generate site capacities v(A), v(B) and v(C) and equilibrium constants K-A, K-B, and K-C for each solute and site. Average site capacities increase (v(A)) < (v(B)) < (v(C)), while equilibrium constants at 25.0 degrees C decrease K-A > K-B > K-C. Site capacities v(i) are independent of temperature and solute molar mass or charge, indicating adsorption through solute nucleobase units. Adenine has unusually high average (v(A)) and (v(B)) related to its ability to dissolve HA at pH 6, but (v(C)) is unexceptional. The equilibrium constant data show that compost-derived HA sites have quite different solute selectivities. For example, site A discriminates poorly between the solutes thymine (4), thymidine (5), and 11 while site C has a strong preference for 4. These selectivities could influence animal, plant, soil, and sediment biochemistry. Linear correlation of the enthalpies and entropies for adsorption of every solute at each HA site points to a common underlying adsorption mechanism.