user: Given these paragraphs about Natural hydrogen, what are some of its sources?

assistant: <think>
Natural hydrogen (known as white hydrogen), is naturally occurring molecular hydrogen on or in Earth (as opposed to hydrogen produced in the laboratory or in industry). The name white hydrogen distinguishes it from green hydrogen, which is produced from renewable energy sources, and from grey, brown or black hydrogen, which is obtained from fossil sources or from the electrolysis of water. Natural hydrogen may be renewable, non-polluting and allows for lower cost operation compared to industrial hydrogen. Natural hydrogen has been identified in many source rocks in areas beyond the sedimentary basins where oil companies typically operate.

Origin of natural hydrogen
There are several sources of natural hydrogen:

- degassing of deep hydrogen from the Earth's crust and mantle;
- reaction of water with ultrabasic rocks (serpentinisation);
- contact of water with reducing agents in the Earth's mantle;
- interaction of water with freshly exposed rock surfaces (weathering);
- decomposition of hydroxyl ions in the structure of minerals;
- Natural radiolysis of water;
- decomposition of organic matter;
- biological activity
- Extraction
- Natural hydrogen is extracted from wells, mixed with other gases such as nitrogen or helium.

Several sources have been identified in France. Geologists Alain Prinzhofer and Eric Derville have demonstrated the existence of large reservoirs in a dozen countries, including Mali and the United States. However, their potential remains difficult to assess.

Numerous emanations on the ocean floor have been identified but are difficult to exploit. The discovery of a significant emergence in Russia in 2008 suggests the possibility of extracting native hydrogen in geological environments.

Geology
Natural hydrogen is generated continuously from a variety of natural sources. There are many known hydrogen emergences on mid-ocean ridges. Another of the known reactions, serpentinisation, occurs under the sea floor (in the oceanic crust).

Diagenetic origin (iron oxidation) in the sedimentary basins of cratons, notably in Russia. Other sources are being explored, such as mantle hydrogen, or hydrogen from radiolysis (natural electrolysis) or from bacterial activity. In France, the Alps and Pyrenees are suitable for exploitation. New Caledonia has hyperalkaline sources that show dihydrogen emissions. A large accumulation of natural hydrogen was discovered in Bourakebougou (Mali).

Characteristics
Dihydrogen is very soluble in fresh water, especially at depth (solubility increases with pressure).

https://en.wikipedia.org/wiki/Natural_hydrogen</think>
degassing of deep hydrogen from the Earth's crust and mantle; reaction of water with ultrabasic rocks (serpentinisation); contact of water with reducing agents in the Earth's mantle; interaction of water with freshly exposed rock surfaces (weathering); decomposition of hydroxyl ions in the structure of minerals; Natural radiolysis of water; decomposition of organic matter; biological activity; Extraction; Natural hydrogen is extracted from wells, mixed with other gases such as nitrogen or helium.

user: Give me a list of Tour de France general Classification winners who have won more than 4 times.

assistant: Jacques Anquetil, Eddie Merckx, Bernard Hinault, Miguel Indurain and Lance Armstrong. Lance Armstrong has won seven times but had those victories rescinded after admitting to using performance enhancing drugs.

user: Why is the Chernobyl disaster considered to be the world's worst-ever civil nuclear incident when only an excess of 15 childhood thyroid cancer deaths were documented as of 2011?

assistant: <think>
The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the No. 4 reactor in the Chernobyl Nuclear Power Plant, near the city of Pripyat in the north of the Ukrainian SSR in the Soviet Union. Called the world's worst-ever civil nuclear incident, it is one of only two nuclear energy accidents rated at seven—the maximum severity—on the International Nuclear Event Scale, the other being the 2011 Fukushima nuclear disaster in Japan. The initial emergency response, together with later decontamination of the environment, involved more than 500,000 personnel and cost an estimated 18 billion roubles—roughly US$68 billion in 2019, adjusted for inflation. Chernobyl's health effects to the general population are uncertain. An excess of 15 childhood thyroid cancer deaths were documented as of 2011. A United Nations committee found that to date fewer than 100 deaths have resulted from the fallout. Determining the total eventual number of exposure related deaths is uncertain based on the linear no-threshold model, a contested statistical model. Model predictions of the eventual total death toll in the coming decades vary. The most widely cited studies by the World Health Organization predict an eventual 9,000 cancer related fatalities in Ukraine, Belarus and Russia.</think>
The Chernobyl disaster was called the world's worst-ever civil nuclear incident because it is one of only two nuclear energy accidents rated at seven—the maximum severity—on the International Nuclear Event Scale. The initial emergency response, together with later decontamination of the environment, involved more than 500,000 personnel and cost an estimated 18 billion roubles—roughly US$68 billion in 2019, adjusted for inflation. Even though Chernobyl's health effects to the general population are uncertain, the World Health Organization predict an eventual 9,000 cancer related fatalities in Ukraine, Belarus and Russia.