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硅是硅藻生长所必需的养分,硅藻在生长过程中从水体吸收主要以硅酸(H4SiO4)形式存在的溶解硅。硅藻δ30Sidiatom可反映硅藻吸收硅酸比例的变化,进一步可以反映湖区气候与环境变化。为探索湖泊沉积物硅藻δ30Sidiatom在指示湖泊古环境方面的潜力,我们测定了湖光岩玛珥湖沉积物硅藻硅同位素变化。研究结果表明,沉积物δ30Sidiatom变化与生物硅和有机碳含量变化呈显著相似性,可作为一种有效的古环境代用指标。同时,与已有温度记录的对比分析表明,两者具有很好一致性。较高的30Sidiatom指示了温度较高的气候条件下硅藻对硅酸的利用率较高;当30Sidiatom较低时,对应着在温度较低的气候条件下硅藻对硅酸的利用率较低。目前,热带陆地区域古气候重建的方法中可用的温度代用指标很少,此项研究证明了δ30Sidiatom是一种很有潜力的古环境代用指标,有望在低纬度地区古温度重建中发挥重要作用,值得进一步深入研究。
Silicon is a nutrient necessary for the growth of diatoms that absorb dissolved silicon, mainly in the form of silicic acid (H4SiO4), from the body of water during growth. The diatom δ30Sidiatom can reflect the change of the proportion of diatom absorbing silicic acid, which can further reflect the climate and environmental changes in the lake. To explore the potentiality of δ30Sidiatom, a diatom lacustrine sediment, in indicating the paleoenvironment of the lake, we measured the diatomite isotopic composition of diatom in Lake Maar Lake sediments. The results show that the δ30Sidiatom variation of sediments is significantly similar to the changes of biosilica and organic carbon content, which can be used as an effective paleo-environmental proxy index. At the same time, the comparison with the existing temperature records shows that the two are in good agreement. The higher 30Sidiatom indicates that diatoms have a higher utilization of silicic acid in higher temperature climates; when 30Sidiatom is low, diatom accounts for the lower utilization of silicic acid in lower temperature climates . At present, there are few available temperature substitution indicators in the paleoclimatic reconstruction of tropical terrestrial regions. This study proves that δ30Sidiatom is a promising paleo-environmental proxy indicator and is expected to play an important role in palaeoclimate reconstruction in low latitudes. Worth further study.