  ZrSiS is the most intensively studied topological nodal-line semimetal
candidate, which is proposed to host multiple nodal lines in its bulk
electronic structure. However, previous angle-resolved photoemission
spectroscopy (ARPES) experiments with vacuum ultraviolet lights mainly probed
the surface states. Here using bulk-sensitive soft X-ray ARPES, we acquire the
bulk electronic states of ZrSiS without any interference from surface states.
Our results clearly show two groups of three-dimensional bulk nodal lines
located on high-symmetry planes and along high-symmetry lines in the bulk
Brillouin zone, respectively. The nodal lines on high-symmetry planes are
enforced to pin at the Fermi level by carrier compensation and constitute the
whole Fermi surfaces. This means that the carriers in ZrSiS are entirely
contributed by nodal-line fermions, suggesting that ZrSiS is a remarkable
platform for studying physical properties related to nodal lines.
