Groundwater Inputs to the Coastal Ocean

SGD = Submarine Groundwater Discharge SGR = Submarine Groundwater Recharge 

The coastal ocean is a dynamic region where the rivers, estuaries, ocean, land, and the atmosphere interact. Coastlines extend over an estimated 350,000 km worldwide, and the coastal ocean is typically defined as a region that extends from the high water mark to the shelf break. 

Some margins receive their terrestrial inputs from estuarine line-sources (numerous estuaries) with very little direct effects from rivers, while others may receive large direct inputs from rivers, such as deltaic regions these differences will have serious consequences on the amount of terrestrial material recycling that has occurred before entering the coastal zone, as well as how these materials (particulate and dissolved) will be transported offshore. 

Rivers transport an estimated 20 Pg y 1(l Pg = 1015 = 1 gigaton) of fluvial sediments to the coastal margin associated with this sediment loading is an estimated 0.21 Pg of POC y-1. Global estimates of riverine flux of DOC to the oceans range from about 0.25 to 0.36 Pg y-1. 

While the coastal ocean has been largely ignored in global carbon budgets, recent work has shown that shelf regions may actually be CO2 sinks recently referred to as the continental shelf pump, that may account for as much as -0.95 Pg C y 1. 

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