科学素养与现象阐释·英语30篇（5）

6 / 30

海洋碳酸盐化学如何缓冲大气CO₂波动

Seawater contains a natural pH buffer system based on dissolved CO₂, carbonic acid, bicarbonate, and carbonate ions.
When atmospheric CO₂ rises, Henry’s law drives increased dissolution—converting CO₂ into HCO₃⁻ with minimal pH change.
This buffering capacity has absorbed ~30% of anthropogenic CO₂ emissions since the Industrial Revolution.
However, excess H⁺ from carbonic acid formation gradually depletes carbonate ion concentration—threatening shell-forming organisms.
The saturation state (Ω) of aragonite—a key biomineral—has declined 15% globally since 1880.
Upwelling zones off Peru and California show seasonal undersaturation, causing oyster larvae mortality spikes.
Ocean alkalinity enhancement proposals aim to restore buffering capacity by adding finely ground olivine.
Modeling future Ω requires coupling atmospheric transport, riverine alkalinity fluxes, and biological calcification rates.
Fisheries management now incorporates carbonate chemistry forecasts alongside traditional stock assessments.
Carbonate buffering explains why ocean pH dropped only 0.1 units despite 120 ppm CO₂ increase—a feat terrestrial systems lack.
Its diminishing efficacy signals a tipping point where marine ecosystems lose adaptive capacity.
This chemistry operates silently beneath policy debates—yet defines the biogeochemical ceiling for climate mitigation.