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Determination of the Gas-phase Acidities of Oligopeptides
Published on: June 24, 2013
海洋pH的冰川 - 间冰川稳定性是从氨基溶解率推断出来的
David M Anderson1, David Archer
1NOAA Paleoclimatology Program and University of Colorado, 325 Broadway, Boulder, Colorado 80303, USA. dma@ngdc.noaa.gov
Nature
|March 8, 2002
概括
海洋pH值和碳酸盐化学对于调节大气中的CO2至关重要. 这项研究发现冰川大西洋碳酸离子度下降,挑战了以前整个海洋的pH偏移理论.
科学领域:
- 古海洋学是古海洋学.
- 地质化学 地质化学
- 气候科学 气候科学
背景情况:
- 海洋pH值和碳酸盐化学在长时间内显著影响大气二氧化碳调节.
- 了解过去的海洋pH值对于理解全球碳循环至关重要.
- 以前的研究表明,在最后的冰川最大值 (LGM) 期间,整个海洋的pH值更为基本.
研究的目的:
- 为了重建冰洋碳酸离子度和pH值.
- 在LGM期间调查海洋在全球碳循环中的作用.
- 将新的重建与基于同位素的先前发现进行比较.
主要方法:
- 使用Climap数据集的类动物群组合.
- 分析碳酸盐在菌中溶解的程度.
- 重建碳酸离子度并推断海洋pH值.
主要成果:
- 观察到,大西洋冰川中的碳酸离子度下降 (~20微摩尔千克-1).
- 与今天相比,在印度洋和太平洋碳酸离子度的变化很小.
- 在太平洋海域,碳酸离子度在3000米以下略有增加 (~5μmolkg-1).
结论:
- 这项研究表明海洋pH值的重新安排,可能与改变的海洋循环模式有关.
- 结果不支持LGM期间整个海洋pH的显著变化,正如以前从同位素中推断的那样.
- 碳酸盐溶解在藻中为重建过去的海洋化学提供了有价值的代理.
相关概念视频
Mixtures of Acids
The pH of a solution containing an acid can be determined using its acid dissociation constant and its initial concentration. If a solution contains two different acids, then its pH can be determined using one of several methods depending upon the relative strength of the acids and their dissociation constants.
A Mixture of a Strong Acid and a Weak Acid
In a mixture of a strong acid and a weak acid, the strong acid dissociates completely and becomes a source of almost all the hydronium ions...
A Mixture of a Strong Acid and a Weak Acid
In a mixture of a strong acid and a weak acid, the strong acid dissociates completely and becomes a source of almost all the hydronium ions...
Determining the pH of Salt Solutions
The pH of a salt solution is determined by its component anions and cations. Salts that contain pH-neutral anions and the hydronium ion-producing cations form a solution with a pH less than 7. For example, in ammonium nitrate (NH4NO3) solution, NO3− ions do not react with water whereas NH4+ ions produce the hydronium ions resulting in the acidic solution. In contrast, salts that contain pH-neutral cations and the hydroxide ion-producing anions form a solution with a pH greater than 7. For...
Henderson-Hasselbalch Equation
The ionization-constant expression for a solution of a weak acid can be written as:
Calculating pH Changes in a Buffer Solution
A buffer can prevent a sudden drop or increase in the pH of a solution after the addition of a strong acid or base up to its buffering capacity; however, such addition of a strong acid or base does result in the slight pH change of the solution. The small pH change can be calculated by determining the resulting change in the concentration of buffer components, i.e., a weak acid and its conjugate base or vice versa. The concentrations obtained using these stoichiometric calculations can be used...
Extraction: Effects of pH
Consider a neutral form of an amine, B, with a partition coefficient, K, in a liquid mixture containing organic and aqueous phases. The pH of the aqueous phase affects the charge on acidic and basic solutes, and the charged form is usually more soluble in the aqueous phase. Suppose the conjugate acid form of the amine is soluble only in the aqueous phase while the base form is soluble in both phases. Then the distribution coefficient, D, can be given as the ratio of amine concentration in the...
Mixtures of Acids
The pH of a solution containing an acid can be determined using its acid dissociation constant and initial concentration. If a solution contains two different acids, then its pH can be determined using one of several methods depending on the relative strength of the acids and their dissociation constants.
In a strong and weak acid mixture, the strong acid dissociates completely and becomes a source of almost all the hydronium ions present in the solution. In contrast, the weak acid shows...
In a strong and weak acid mixture, the strong acid dissociates completely and becomes a source of almost all the hydronium ions present in the solution. In contrast, the weak acid shows...

