This fresher water is evidently derived in great measure directly from precipitation, which is here in excess of the evaporation from the surface of the sea.
(This fresher water; is evidently derived directly; from precipitation) (precipitation; is; here in excess of the evaporation from the surface of the sea)
This fresher water precipitation
is evidently derived directly is
from precipitation
here in excess of the evaporation from the surface of the sea