Calcium carbonate global LGM Burial rate data

Global databases of calcium carbonate concentrations and mass accumulation rates in Holocene and last glacial maximum sediments were used to estimate the deep-sea sedimentary calcium carbonate burial rate during these two time intervals. Sparse calcite mass accumulation rate data were extrapolated across regions of varying calcium carbonate concentration using a gridded map of calcium carbonate concentrations and the assumption that accumulation of noncarbonate material is uncorrelated with calcite concentration within some geographical region. Mean noncarbonate accumulation rates were estimated within each of nine regions, determined by the distribution and nature of the accumulation rate data. For core-top sediments the regions of reasonable data coverage encompass 67% of the high-calcite (>75%) sediments globally, and within these regions we estimate an accumulation rate of 55.9 ± 3.6 x 10**11 mol/yr. The same regions cover 48% of glacial high-CaCO3 sediments (the smaller fraction is due to a shift of calcite deposition to the poorly sampled South Pacific) and total 44.1 ± 6.0 x 10**11 mol/yr. Projecting both estimates to 100 % coverage yields accumulation estimates of 8.3 x 10**12 mol/yr today and 9.2 x 10**12 mol/yr during glacial time. This is little better than a guess given the incomplete data coverage, but it suggests that glacial deep sea calcite burial rate was probably not considerably faster than today in spite of a presumed decrease in shallow water burial during glacial time.

本研究借助全新世（Holocene）与末次冰盛期（Last Glacial Maximum）沉积物中的碳酸钙（calcium carbonate）浓度及质量累积速率全球数据库，估算了这两个时段深海沉积物的碳酸钙埋藏速率。针对稀疏的方解石（calcite）质量累积速率数据，本研究借助碳酸钙浓度网格化分布图，并假设在特定地理区域内，非碳酸盐物质的累积与方解石浓度无关，对不同碳酸钙浓度区域的数据进行了外推。根据累积速率数据的分布与特征，将研究区划分为9个区域，并分别估算了每个区域的平均非碳酸盐物质累积速率。对于岩芯表层沉积物，数据覆盖较为合理的区域覆盖了全球67%的高方解石（方解石含量>75%）沉积物，在此类区域中，我们估算的累积速率为55.9±3.6×10^11 mol/yr。上述区域同时覆盖了48%的冰期高碳酸钙沉积物（占比偏低的原因是方解石沉积作用向采样不足的南太平洋转移），总累积速率为44.1±6.0×10^11 mol/yr。将这两类估算结果外推至100%数据覆盖的情况，可得现代深海方解石累积速率为8.3×10^12 mol/yr，冰期则为9.2×10^12 mol/yr。鉴于数据覆盖并不完整，该估算结果仅略优于推测，但它表明：尽管学界普遍认为冰期浅水碳酸钙埋藏速率有所下降，但冰期深海方解石埋藏速率大概率并未显著高于现代。