Can marginal seas account for the missing CO2 and is the marginal sea sink affected by human activities on land?

Current estimate of CO2 uptake by the oceans by and large ignored marginal seas and continental shelves. Preliminary investigations indicate that these areas are a larger sink of CO2 than open oceans on the per area basis. If proven, this sink may be as large as 25% of the oceanic sink. Human activities on land are affecting this sink via construction of dams, increasing nutrient discharge into the continental shelves, etc. Global synthesis, however, is nonexistent because of insufficient data.