Ingram B L, Sloan D
Science. 1992 Jan 3;255(5040):68-72. doi: 10.1126/science.255.5040.68.
The strontium isotopic composition of biogenic precipitates that occur in estuarine sediments can be used as proxy indicator of paleosalinity and for assessing precipitation and river discharge rates over thousands of years. In the San Francisco Bay estuary, river water with low (87)Sr/(86)Sr ratio (average, 0.7065) and low Sr concentration (0.13 parts per million) mixes with seawater with a higher (87)Sr/(86)Sr ratio (0.7092) and Sr concentration (7.9 parts per million). The predicted mixing relation between salinity and Sr isotopic composition is confirmed by measurements of modern estuarine surface waters. A paleosalinity record obtained from foraminifera for the ancestral San Francisco Bay during oxygen isotope substage 5e of the last interglacial reflects a global rise and fall of sea level, and short time-scale variations related to fluctuations in discharge rates of the Sacramento and San Joaquin rivers.
河口沉积物中生物成因沉淀物的锶同位素组成可作为古盐度的替代指标，并用于评估数千年来的降水量和河流流量。在旧金山湾河口，低（87）Sr/（86）Sr比值（平均为0.7065）和低锶浓度（百万分之0.13）的河水与较高（87）Sr/（86）Sr比值（0.7092）和锶浓度（百万分之7.9）的海水混合。现代河口表层水的测量结果证实了盐度与锶同位素组成之间的预测混合关系。从末次间冰期氧同位素亚阶段5e的旧金山湾祖先有孔虫获得的古盐度记录反映了全球海平面的上升和下降，以及与萨克拉门托河和圣华金河流量波动相关的短时间尺度变化。
