  We revisit the big bang nucleosynthesis (BBN) limits on primordial magnetic
fields and/or turbulent motions accounting for the decaying nature of turbulent
sources between the time of generation and BBN. This leads to larger estimates
for the gravitational wave (GW) signal than previously expected. We address the
detection prospects through space-based interferometers (for GWs generated
around the electroweak energy scale) as well as pulsar timing arrays and
astrometric missions (for GWs generated around the quantum chromodynamics
energy scale).
