Coolant lines on the turbo possibly, check the clamps. There is the big crossover hard pipe that could be leaking, that you would have to remove the intake manifold to replace the o-rings. Check the hose underneath the top little coolant tank, that is right in the area. You could unscrew the tank and move it a little so you get a better view, or even just drain some of the coolant and pull it off.
Most likely just a clamp that got loose.