How phosphorus limitation can control climate-active gas sources and sinks

Abstract

Since the 1950's, anthropogenic activities have increased nutrient river loads to European coastal areas. Subsequent implementation of nutrient reduction policies have led to considerably reduction of phosphorus (P) loads from the mid-1980's, while nitrogen (N) loads were maintained, inducing a P limitation of phytoplankton growth in many eutrophied coastal areas such as the Southern Bight of the North Sea (SBNS). When dissolved inorganic phosphorus (DIP) is limiting, most phytoplankton organisms are able to indirectly acquire P from dissolved organic P (DOP). We investigate the impact of DOP use on phytoplankton production and atmospheric fluxes of CO 2 and dimethylsulfide (DMS) in the SBNS from 1951 to 2007 using an extended version of the R-MIRO-BIOGAS model. This model includes a description of the ability of phytoplankton organisms to use DOP as a source of P. Results show that primary production can increase up to 30% due to DOP uptake under limiting DIP conditions. Consequently, simulated DMS emissions also increase proportionally while CO 2 emissions to the atmosphere decrease, relative to the reference simulation without DOP uptake.

Dissolved trace elements and nutrients in the North Sea—a current baseline

“…However, riverine input is important for the duration of the bloom and phytoplankton growth, especially in coastal regions (Frigstad et al, 2020 ; Gross et al, 2022 ; Skogen et al, 2004 ). Limitations of specific nutrients can cause a shift in the phytoplankton community, due to the different demands of the species (Gross et al, 2022 ; Grosse et al, 2017 ; Gypens et al, 2017 ). Hence, unbalanced nutrient inputs can support toxic algae blooms (Emeis et al, 2015 ; Lefebvre & Dezecache, 2020 ).…”