概括
大气中的核试验,主要是在圣诞岛,是1962年5月至6月中西部牛奶中-131的主要来源. 雷暴充当了一种清理机制,将核废料拖入平流层的下层,并影响牛奶污染水平.
科学领域:
- 环境科学 环境科学
- 核化学 核化学 核化学
- 大气科学 大气科学
背景情况:
- 牛奶中的放射性 (-131) 污染在核试验时代引起了公众健康的关注.
- 了解-131的来源和运输机制对于评估环境和健康风险至关重要.
研究的目的:
- 确定1962年5月至6月中西部牛奶样本中-131度显著的主要来源.
- 调查大气和地下核试验在牛奶污染中的作用.
- 研究气象因素,特别是雷暴对放射性水平的影响.
主要方法:
- 对牛奶样本进行-131度分析.
- 污染水平与已知的核试验事件 (大气和地下) 的比较.
- 检查雨水样本以确认大气清理机制.
主要成果:
- 圣诞岛的大气测试被确定为牛奶中-131升高 (>300 pCi/L) 的主要来源.
- 在内华达州的地下测试在指定的期间起到了很小的作用.
- 观察到雷暴活动穿透核废物层和牛奶中随后的-131水平之间存在直接关系.
结论:
- 大气中的核试验是造成大量-131牛奶污染的主要原因.
- 雷暴的"清理"效应是将平流层核废料转移到热带层,随后转移到牛奶的关键因素.
- 在1961年9月至1963年12月期间,地下测试对-131污染牛奶的贡献很小.
相关概念视频
Precipitation of Ions
Predicting Precipitation
The equation that describes the equilibrium between solid calcium carbonate and its solvated ions is:
The equation that describes the equilibrium between solid calcium carbonate and its solvated ions is:
Chemical Ionization (CI) Mass Spectrometry
The molecular ion peak of a molecule in the mass spectrum provides vital information for molecular identification. However, conventional electron impact ionization can lead to the rapid dissociation of some molecular ions before they reach the detector. A milder ionization method is required to increase the lifetime of such ionized analyte molecules. Chemical ionization (CI) is a gas-phase protonation reaction useful for mass-analyzing analyte molecules that are easily protonated to yield the...
Precipitation Titration: Overview
Precipitation titration involves the reaction of a titrant and an analyte to generate an insoluble precipitate. While precipitation titration uses various precipitating agents, silver nitrate is the most common precipitating reagent; titrations involving Ag+ are called argentometric titrations. Usually, the endpoint in a precipitation titration can be detected by visual indicators.
A precipitation titration curve demonstrates the change in concentration of the titrant or analyte upon adding the...
A precipitation titration curve demonstrates the change in concentration of the titrant or analyte upon adding the...
Precipitation Titration Curve: Analysis
The precipitation titration curve demonstrates the change in concentration of one reactant with the volume of titrant added. During the titration of chloride ions with silver nitrate, the precipitation titration curve is divided into three regions: before, at, and after the equivalence point. Before the equivalence point, low redissolution of the sparingly soluble silver chloride precipitate gives a low silver ion concentration. However, in the second region, representing the equivalence point,...
Precipitation Titration: Endpoint Detection Methods
In argentometric precipitation titrations, endpoints can be detected visually by the Mohr, Volhard, and Fajans methods. In the Mohr method, adding a soluble chromate indicator gives an initial yellow color to the analyte solution. As the titrant is added, the first excess of silver ions forms a red silver chromate precipitate, marking the endpoint. The solution pH should be maintained at about 8 by adding solid CaCO3.
In the Volhard method, a standard excess of AgNO3 is first added to the...
In the Volhard method, a standard excess of AgNO3 is first added to the...
Acid–Base Titration: Overview
An acid-base titration is a technique used to determine the concentration of an unknown acid or base, using a titrant of known concentration–either a base for acid titration or an acid for base titration. The process involves gradually adding the titrant, leading to a predictable change in the pH of the solution. This change is plotted on a titration curve, showing how a solution's pH varies with the amount of titrant added. Such curves are instrumental in monitoring the titration's progress...


