Wastewater inputs reduce the CO2 uptake by coastal oceans

Every year a large quantity of wastewater is generated worldwide, but its influence on the carbon dioxide (CO2) uptake by coastal oceans is not well understood. Here, sea surface CO2 partial pressure (pCO2) and air-sea CO2 flux were examined in the Jiaozhou Bay (JZB), a temperate coastal bay strongly disturbed by wastewater inputs. Monthly surveys from April 2014 through March 2015 showed that surface pCO2 in the JZB substantially varied both temporally and spatially between 163 μatm and 1222 μatm, with an annual average of 573 μatm. During April–December, surface pCO2 was oversaturated with respect to the atmosphere, with high values exceeding 1000 μatm in the northeastern part of the bay, where seawater salinity was low mainly due to the inputs of wastewater with salinity close to zero. During January–March, surface pCO2 was undersaturated, with the lowest value of