Two decades of inorganic carbon dynamics along the West Antarctic Peninsula

[摘要] We present 20 years of seawater inorganic carbon measurements collected alongthe western shelf and slope of the Antarctic Peninsula. Water columnobservations from summertime cruises and seasonal surface underway pCO₂measurements provide unique insights into the spatial, seasonal, andinterannual variability in this dynamic system. Discrete measurements fromdepths > 2000 m align well with World Ocean CirculationExperiment observations across the time series and underline the consistencyof the data set. Surface total alkalinity and dissolved inorganic carbon datashowed large spatial gradients, with a concomitant wide range ofΩ_arag (< 1 up to 3.9). This spatial variability wasmainly driven by increasing influence of biological productivity towards thesouthern end of the sampling grid and meltwater input along the coast towardsthe northern end. Large inorganic carbon drawdown through biologicalproduction in summer caused high near-shore Ω_arag despiteglacial and sea-ice meltwater input. In support of previous studies, weobserved Redfield behavior of regional C / N nutrient utilization, whilethe C / P (80.5 ± 2.5) and N / P (11.7 ± 0.3) molarratios were significantly lower than the Redfield elemental stoichiometricvalues. Seasonal salinity-based predictions of Ω_arag suggestthat surface waters remained mostly supersaturated with regard to aragonitethroughout the study. However, more than 20 % of the predictions forwinters and springs between 1999 and 2013 resulted in Ω_arag< 1.2. Such low levels of Ω_arag may have implicationsfor important organisms such as pteropods. Even though we did not detect anystatistically significant long-term trends, the combination of on\-goingocean acidification and freshwater input may soon induce more unfavorableconditions than the ecosystem experiences today.

[学科分类] 地球化学与岩石