Ed Roland
Addicted to ArboristSite
Your problem is cultural.
The problem this person has is root crown rot due to deep planting and excessive watering.
Hmmm, could be... perhaps a nice fat conk sitting where that little bit of algae resides...
"White pine is very susceptible to damage by salt. This species is also considered sensitive to air pollution, particularly ozone. There are a total of 277 insects and 110 disease organisms known to attack white pine."
From the good people @ BTRL
Could be any number of things. Thats why it is so important to have a qualified pro come to the property to view the soil, touch the tree and collect the necessary samples for pathology in an effort to identify the issue. Master arborist or not, it is impossible to say definitively what the causal is from 5 photos.
His guess is as good as any though.