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双壳类壳体碳酸盐(文石)稳定同位素组成已被广泛地用于古气候和古环境重建研究中,但是双壳类壳体碳同位素组成所指示的气候和环境意义一直是争议的问题。对双壳类河蚬(corbicula fluminea)进行了室内养殖,并选取两个壳体样品(壳高,A=13mm,B=9mm),测定其生长部分壳体和生长期间水体碳同位素,研究表明,随着水体碳同位素的升高(δ13CDIC由-5.24‰升至1.41‰),两壳体碳同位素也随之升高,表明水体对壳体碳同位素的影响;δ13CA分布范围为-4.76‰～-2.09‰,δ13CB为-8.49‰～-2.89‰,壳体A和B碳同位素均比预测平衡值偏负,表明壳体在形成过程中利用了新陈代谢产生的富集12C的CO2。根据计算壳体A在实验中沉淀部分壳体利用新陈代谢碳的比例(M值)为24%～43%,平均值为33%;壳体B为33%～75%,平均值为58%。M值随生物的生长呈下降变化,这说明在实验中河蚬主要是通过增加对DIC的吸收和利用来满足壳体生长对物质量增加的需求。
The carbonate (aragonite) stable isotopic compositions of bivalve shells have been widely used in paleoclimate and paleoenvironmental reconstruction studies, but the climatic and environmental implications of the carbon isotopic composition of bivalve shells have been controversial problem. The corbicula fluminea was bred indoors, and two shell samples (shell height, A = 13 mm, B = 9 mm) were selected for the determination of the growth part of the shell and the carbon isotope of water during growth (Δ13CDIC increased from -5.24 ‰ to 1.41 ‰), the carbon isotopes of the two crusts also increased, indicating the influence of water body on the carbon isotope of the crust. The distribution range of δ13CA was -4.76 ‰ ~ -2.09 ‰ and δ13CB ranged from -8.49 ‰ to -2.89 ‰. The A and B carbon isotopes of shell A and B were all negatively correlated with the predicted equilibrium values, indicating that the shell used the CO2-enriched 12C generated during the formation process. According to the calculation, the proportion (M value) of the utilization of the metabolic carbon by the shell in the shell A was 24% ~ 43% and the average was 33% in the shell A, and 33% ~ 75% in the shell B with the average value of 58%. The value of M decreased with the growth of the organism, indicating that in the experiment, the river 蚬 mainly meets the demand of increasing the mass of the shell by increasing the absorption and utilization of DIC.