科学术语“cal BP”是“现在之前校准的年份”或“现在之前的日历年”的缩写,这是指考古学家在放射性碳曲线中发现产生可用年代的摆动的事实。对曲线的调整以校正摆动(“摆动”实际上是研究人员使用的科学术语)被称为校准。 cal BP,cal BCE和cal CE(以及cal BC和cal AD)的名称都表示所提到的放射性碳日期已经过校准以解释那些摆动;未调整的日期被指定为RCYBP“现在之前的放射性碳年”。放射性碳测年是科学家们可以使用的最着名的考古约会工具之一,大多数人至少听说过它。但是关于放射性碳如何工作以及它的技术可靠性存在很多误解;本文将尝试清除它们。所有生物都将气体碳14(缩写为C14,14C,最常见的是14C)与它们周围的大气交换 – 动物和植物将碳14与大气交换,鱼和珊瑚在水中与溶解的14C交换碳。在动物或植物的整个生命周期中,14C的量与其周围环境的量完全平衡。当有机体死亡时,这种平衡就会被打破。死亡生物中的14C以已知的速度慢慢衰变:它的“半衰期”。像14C这样的同位素的半衰期是其中一半衰变所需的时间:在14C,每5,730年,其中一半消失了。因此,如果你测量死亡生物体中14C的含量,你可以计算出它停止与大气交换碳的时间。鉴于相对原始的情况,放射性碳实验室可以在长达5万年前准确测量死亡生物体中的放射性碳量;在此之后,还没有足够的14C来衡量。

新加坡国立大学化学Essay代写:放射性碳

The scientific term “cal BP” is an abbreviation for “the year before calibration” or “the calendar year before now”, which refers to the fact that archaeologists have found a swing in the radiocarbon curve that produces usable age. The adjustment of the curve to correct the wobble (“swing” is actually the scientific term used by the researcher) is called calibration. The names of cal BP, cal BCE and cal CE (and cal BC and cal AD) indicate that the radiocarbon dates mentioned have been calibrated to account for those swings; the unadjusted date is designated as RCYBP “now the radiocarbon year before “. Radiocarbon dating is one of the most famous archaeological dating tools available to scientists, and most people have heard of it at least. But there are many misconceptions about how radiocarbon works and its technical reliability; this article will try to clean them up. All organisms exchange gaseous carbon 14 (abbreviated as C14, 14C, most commonly 14C) with the atmosphere around them – animals and plants exchange carbon 14 with the atmosphere, and fish and coral exchange carbon with dissolved 14C in water. During the entire life cycle of an animal or plant, the amount of 14C is perfectly balanced with the amount of its surroundings. When the organism dies, this balance is broken. 14C in the dead organism slowly decays at a known rate: its “half-life”. The half-life of an isotope like 14C is the time required for half of it to decay: at 14C, every 5,730 years, half of it disappears. Therefore, if you measure the 14C content of a dead organism, you can calculate the time it stops carbon exchange with the atmosphere. Given the relatively primitive situation, radiocarbon laboratories can accurately measure the amount of radioactive carbon in dead organisms up to 50,000 years ago; after that, there is not enough 14C to measure.

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