In addition to producing a strong gravitational-wave signal and a short gamma-ray burst (GRB), neutron star mergers eject significant masses at significant kinetic energies. Such a mass ejection produces a large variety of electromagnetic signatures including a macronova, also called a kilonova, and a long-lasting radio flare. Discoveries of macronova/kilonova candidates associated with the short GRB 130603B and GRB 060614 are the direct observational evidence of the mass ejection. I will show the estimates of the ejecta mass. The late time radio observations also can limit on the ejecta's kinetic energy. I will discuss compact binary mergers as the origin of heavy r-process elements. I will show that both the total r-element mass in the Galaxy and the 244Pu accumulation measurements on the Earth's deep-sea floor are compatible with the merger scenario.