A nitrogen fixation estimate for the Baltic Sea based on continuous pCO2 measurements on a cargo ship and total nitrogen data

Schneider, Bernd; Kaitala, Seppo; Raateoja, Mika; Sadkowiak, Bernd

doi:10.1016/j.csr.2009.04.001

Cited by 40 publications

(48 citation statements)

References 19 publications

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“…Thus, when the oxygen concentration reaches zero, the denitrification rate can be anything from very high to nonexistent. Literature estimates of contemporary annual N 2 fixation in the Baltic Proper span a wide range; 180-552 kton year -1 (Larsson et al 2001;Wasmund et al 2001Wasmund et al , 2005Rolff et al 2007;Savchuk and Wulff 2009;Schneider et al 2009). Our simulated average N 2 fixation rate in 1980-2014 is 408 ± 130 kton N year -1 in the EBS (Table 6).…”

Section: Biogeochemical Fluxesmentioning

confidence: 99%

Key processes in the coupled carbon, nitrogen, and phosphorus cycling of the Baltic Sea

et al. 2017

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In this study we examine pools of carbon (C), nitrogen (N), and phosphorus (P) in the Baltic Sea, both simulated and reconstructed from observations. We further quantify key fluxes in the C, N, and P cycling. Our calculations include pelagic reservoirs as well as the storage in the active sediment layer, which allows a complete coverage of the overall C, N, and P cycling on a system-scale. A striking property of C versus N and P cycling is that while the external supplies of total N and P (TN and TP) are largely balanced by internal removal processes, the total carbon (TC) supply is mainly compensated by a net export out of the system. In other words, external inputs of TN and TP are, in contrast to TC, rather efficiently filtered within the Baltic Sea. Further, there is a net export of TN and TP out of the system, but a net import of dissolved inorganic N and P (DIN and DIP). There is on the contrary a net export of both the organic and inorganic fractions of TC. While the pelagic pools of TC and TP are dominated by inorganic compounds, TN largely consists of organic N because allochthonous organic N is poorly degradable. There are however large basin-wise differences in C, N, and P elemental ratios as well as in inorganic versus organic fractions. These differences reflect both the differing ratios in external loads and differing oxygen conditions determining the redox-dependent fluxes of DIN and DIP.

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Section: Biogeochemical Fluxesmentioning

confidence: 99%

Key processes in the coupled carbon, nitrogen, and phosphorus cycling of the Baltic Sea

et al. 2017

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“…For surface water in the eastern Gotland Sea, a maximum oversaturation is obtained for calcite during midsummer (1.65), whereas a slight undersaturation (0.92) was found for aragonite. Despite an increase in atmospheric CO 2 by about 80 ppm since Buch's measurements, the surface water saturation for calcite and aragonite in midsummer did not decrease, but instead increased by a factor of 2.6 during the last 80 years according to pCO 2 measurements performed in 2005 (Schneider et al 2009). This is mainly a consequence of the low pCO 2 that is caused by the eutrophication-related high production and that has completely overridden the effect of the rising atmospheric pCO 2 .…”

Section: Past Changesmentioning

confidence: 99%

“…18.10). According to measurements in 2005 (Schneider et al 2009), this results in a distinct calcite and aragonite undersaturation during winter of 0.56 and 0.31, respectively.…”

Section: Past Changesmentioning

confidence: 99%

“…Due to the intense N 2 fixation in July, the DpCO 2 in the central Baltic Sea currently amounts to almost −300 µatm (Schneider et al 2009), whereas the mean DpCO 2 at this time of year for 1927-1935 was less than −40 µatm (Buch 1945). This indicates low or even absent N fixation activity before the onset of the eutrophication.…”

Section: Past Changesmentioning

confidence: 99%

“…Observations suggest an increase in cyanobacteria after the 1960s (Finni et al 2001). Furthermore, budgets for CO 2 and total N in the surface water of the central Baltic Sea indicated an increase in N fixation by cyanobacteria of 30 % within the past two decades (Schneider et al 2009). Model studies suggest a fourfold ) to 10-fold (Savchuk et al 2008) increase in N fixation since 1900.…”

Section: Past Changesmentioning

confidence: 99%

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Environmental Impacts—Marine Biogeochemistry

Schneider

Eilola

Lukkari

et al. 2015

Regional Climate Studies

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Marine biogeochemistry deals with the budgets and transformations of biogeochemically reactive elements such as carbon, nitrogen and phosphorus. Inorganic nitrogen and phosphorus compounds are the major nutrients and control organic matter (biomass) production in the surface water. Due to various anthropogenic activities, the input of these nutrients into the Baltic Sea has increased drastically during the last century and has enhanced the net organic matter production by a factor of 2-4 (eutrophication). This has led to detrimental oxygen depletion and hydrogen sulphide production in the deep basins of the Baltic Sea. Model simulations based on the Baltic Sea Action Plan (BSAP) indicate that current eutrophication and thus extension of oxygen-depleted areas cannot be reversed within the next hundred years by the proposed nutrient reduction measures. Another environmental problem is related to decreasing pH (acidification) that is caused by dissolution of the rising atmospheric CO 2 . Estimates indicate a decrease in pH by about 0.15 during the last 1-2 centuries, and continuation of this trend may have serious ecological consequences. However, the concurrent increase in the alkalinity of the Baltic Sea may have significantly counteracted acidification.

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The air‐water CO₂ exchange of a coastal sea—A sensitivity study on factors that influence the absorption and outgassing of CO₂ in the Baltic Sea

2015

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In this study, the BALTSEM model is used to estimate how air‐water CO2 fluxes in the Baltic Sea respond to parameterizations of organic alkalinity (Aorg), gas transfer, and phytoplankton growth, and further to changes in river loads. The forcing data include the most complete compilation of Baltic river loads for dissolved inorganic and organic carbon (DIC and DOC) and total alkalinity (TA). In addition, we apply the most recent estimates of internal TA generation in the system. Our results clearly demonstrate how air‐water CO2 fluxes of a coastal sea depend on river loads of carbon, TA, and nutrients as well the freshwater import itself. Long‐term changes in DIC loads are shown to be compensated by corresponding changes in air‐water CO2 exchange. By adding Aorg, a discrepancy in the carbonate system calculations was removed, and the simulated net CO2 absorption of the system decreased by 11%. A new parameterization for cyanobacteria growth significantly improved the seasonal development of pCO2 in the central Baltic Sea, although the net effect on CO2 fluxes was below 5%. By applying either a linear, quadratic, or cubic wind speed dependence for gas transfer, the long‐term net CO2 exchange was adjusted by less than 5%. There is no clear indication that any one of these parameterizations provides a more accurate estimate of CO2 fluxes than the other two. Our findings are applicable in other coastal areas that are heavily influenced by river loads of TA, DIC, and DOC.

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A nitrogen fixation estimate for the Baltic Sea based on continuous pCO2 measurements on a cargo ship and total nitrogen data

Cited by 40 publications

References 19 publications

Key processes in the coupled carbon, nitrogen, and phosphorus cycling of the Baltic Sea

Key processes in the coupled carbon, nitrogen, and phosphorus cycling of the Baltic Sea

Environmental Impacts—Marine Biogeochemistry

The air‐water CO₂ exchange of a coastal sea—A sensitivity study on factors that influence the absorption and outgassing of CO₂ in the Baltic Sea

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A nitrogen fixation estimate for the Baltic Sea based on continuous pCO2 measurements on a cargo ship and total nitrogen data

Cited by 40 publications

References 19 publications

Key processes in the coupled carbon, nitrogen, and phosphorus cycling of the Baltic Sea

Key processes in the coupled carbon, nitrogen, and phosphorus cycling of the Baltic Sea

Environmental Impacts—Marine Biogeochemistry

The air‐water CO2 exchange of a coastal sea—A sensitivity study on factors that influence the absorption and outgassing of CO2 in the Baltic Sea

Contact Info

Product

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The air‐water CO₂ exchange of a coastal sea—A sensitivity study on factors that influence the absorption and outgassing of CO₂ in the Baltic Sea