Article reprinted from "Gezhi Discourse Forum"
I named the Raman probe RiP.
Because it's just a passer-by at the bottom of the sea,
will not destroy the environment in which those creatures live,
It will not disturb the blue world.
Zhang Xin· Institute of Oceanology, Chinese Academy of Sciences
Ge Zhi said | September 5, 2020 Beijing
What is in the deep sea? Is it a desert?
The average depth of the ocean has reached more than 3700 meters, while the deep sea area of more than 1000 meters has exceeded 90%.
The general view is that below the true light layer below 200 meters, there is almost no life of all kinds. It was also in 1977, before the discovery of hydrothermal systems in the deep sea, which was considered to be a desert.
However, there are various extreme environments under the deep sea.
Extreme environments under the deep sea
Completed: 10%///////
A more extreme example is called hydrothermal systems in the deep sea.
▲ Deep-sea hydrothermal system: Hydrothermal vent fluid is generally high temperature, rich in methane, carbon dioxide and other gases and metal mineral particles, most of which are acidic
This system is formed by the rapid ejection of large amounts of high-temperature, high-pressure, strong acid or strong alkali fluids on the seafloor. It carries a large amount of methane, carbon dioxide gas, as well as a variety of metallic elements, which can accumulate on the seabed to form hydrothermal sulfide minerals. At the same time, it also gave birth to various phenomena of life.
▲ Deep-sea cold spring system: The cold spring fluid is mainly water, methane, hydrogen sulfide, and fine-grained sediments, and the fluid temperature is similar to the temperature of the surrounding seawater
Another kind of ecosystem, we call it cold springs. Cold springs are not cold, it is only after the discovery of hydrothermal fluids that we find that there is a low temperature fluid.
Its temperature is comparable to that of the surrounding seawater, and the substances contained in it do not have a large number of metal sulphide particles, but mainly water, methane, hydrogen sulfide and some fine sediments.
It also gave birth to an energy source, or strategic energy of the future, which we call combustible ice. Therefore, its resources and energy, or effects, are indisputable.
The extreme environment of hot liquid cold springs also gave birth to a special phenomenon of life.
It is generally believed that all things grow by the sun, which requires photosynthesis, and there is no life without light.
▲ The extreme environment of the deep sea gives birth to special life processes
Later, we found that this creature in the deep sea is particularly magical, it can use the methane and hydrogen sulfide gases spewed from hot and liquid cold springs to convert inorganic matter into organic matter through microbial synthesis, and then produce macromolecules.
This phenomenon of life does not require the participation of light, we call it a chemically synthesized autotrophic ecosystem.
Is it feasible to bring deep-sea samples directly back to the lab?
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Since the seabed has this particularly magical ecosystem, which is completely different from our surface ecosystem, we have to explore it.
Is it possible to directly bring everything in the hot liquid cold spring back to the laboratory for various analyses? Probably not quite.
▲ Inaccurate
First of all, you can't measure it.
▲ The test is not correct
It is also possible that the test is not correct. The points at the bottom are obtained by the International Ocean Drilling Program using non-insulated and packed technology, which is the traditional sediment sampling technique.
The concentration of methane in the pore water of the sediment is about 1 mmol. What is the concept of 1 millimole? It is the solubility of methane in water at normal 25 degrees and 1 atmosphere.
The upper black spots were obtained using a new technology, called thermal insulation and pressure retention sampling technology. Its methane concentration can reach 1000 mmol.
If this is its true concentration, then the traditional measured data and the true concentration are 1,000 times different. Therefore, a lot of data is inaccurate.
Also, it breaks down and spoils easily.
In the South China Sea of our country, I conducted an in situ synthesis experiment of natural gas hydrates, also called combustible ice.
▲At 3 °C in the deep sea, 11Mpa (1100 m) synthetic natural gas hydrate (combustible ice)
I synthesized the gas hydrate in situ at a depth of 11 MPa at 3 degrees, 1100 meters.
▲ The synthetic natural gas hydrate (combustible ice) begins to decompose at 7 °C and 7Mpa (700 m).
When I took it to a depth of 700 meters and the water temperature was about 7 degrees, it had already begun to decompose, so it did not reach the surface of the sea at all.
So a lot of the things that may be brought back are no longer these material components in situ.
▲ Can't be harvested
Also, you can't pick it up.
This white one is a submarine shrimp, and underneath are some deep-sea clams. Further down is the substrate on which it grows, which we call the autobiogenic carbonate rock. This substance between the autobiogenic carbonate rock and the submerged shrimp is called subsurface water in the biome.
This fluid cannot be mined because it is only about a few centimeters to a dozen centimeters thick, and it is impossible to obtain it by various sampling techniques.
Self-growing carbonate rock, such a large piece of stone, can not all be moved back to the laboratory.
Therefore, we take the sample back to the laboratory and analyze the various data, which may not represent the true value of the data, or we cannot take the sample at all.
Take the probe to the dive
Completed: 30%/////////
So how?
The work I've been doing recently, or the work I've been doing for the last dozen years, hasn't fulfilled my dream of moving the lab to the bottom of the ocean.
▲ Serialized Raman probes
I just made a simple probe called the Raman Spectroscopic Probe and took it to the dive.
It has been three generations since my first probe sediment pore water probe was born around 2008.
What can be done? It can detect sediment pore water and cold spring fluids, and can detect natural gas hydrates, also known as combustible ice. Finally, and recently, our breakthrough is the ability to detect hydrothermal vent fluids at high temperatures and pressures.
This probe is a particularly large system that uses our Discovery robot.
Where is the Discovery robot?
It is an ROV robot that is carried to a major infrastructure in our country, the scientific expedition ship "Science". This robot is like a human, can do all kinds of operations under the seabed, I use almost all the functions of this robot.
I'm going to use its electricity to power my probes, to use its communications to control my probes for various operations, and I need to use the robot's two hands to grasp the probes to detect different locations.
That probe is like the laser sword in Star Wars, it points to where to fight.
Of course, this hand is a mechanical hand, so where does it really point?
First, I made some solid material on the seabed.
Natural gas hydrates, also known as combustible ice, were first discovered in the South China Sea, where this combustible ice is exposed on the seabed. The laser sword emits a blue-green laser beam that hits the surface of the combustible ice and we can get its chemical composition.
But now the combustible ice in the cold spring vent is impossible to bring back the sample. After this beam of light hits, it takes back all its material components.
We not only do the detection of the composition of the material, we also do in situ experiments under the seabed.
▲ Natural gas hydrate
This honeycomb-like device is that we synthesized combustible ice using cold spring fluids on the seabed, and then found that under the seabed, combustible ice could be synthesized in 0 seconds.
And if in the laboratory it may take a few days, more than ten days to synthesize. Why?
Because the cold spring fluid contains a large number of mineral particles, it is like our artificial rain core, which will rapidly increase the formation rate of combustible ice.
▲ Autobiosis carbonate rock/hydrothermal sulfide
I probed the self-generated carbonate rocks of cold springs and the sulfides of hydrothermal fluids.
After taking the probe into the sea, probe at each point, just like you're doing CT, so that you get an ecosystem, or a model and pattern of fluid formation.
In addition to this stone and hydrate, I also probe creatures.
Rest assured, none of the creatures I'm probing now are dead, and they're well surviving in our deep sea.
The name I gave the Raman probe, like my child, was RiP.
What is RiP? If you have been abroad, you may find that the tombstones in the cemetery have RIP, which means rest.
The work I want to do with a Raman probe is also, just hit a beam of light past, and then the return signal of this beam of light can tell me your physiological state, or your chemical composition, but I will not destroy the environment in which you live.
So they're resting in peace, we just look at it in the past, we're like passers-by.
▲ Seabed organisms: anemones/snails/mussels
So what's the difference between red and white anemones? Quite simply, there are carotenoids in the red sea anemone, which is found in large organisms.
I also went to test all kinds of snails, and those snails looked about the same length as the conch you ate, but its material composition was very different.
After measuring so many solid matter, what is the measurement point at other times?
Let's either measure some fluids. So what's in the fluid?
First I made deposits of pore water.
What is sediment pore water?
As you can imagine, you take a piece of mud from the ground into your hand, and you squeeze it so hard that you might squeeze out a little water. Or when you're playing with your kids on the beach, take out a bunch of sand and the water will drip down.
Pore water is the water in the middle of this sediment or rock, or this sandy sediment argillaceous sediment.
So why measure it? Because there are a large number of this methane oxidizing bacteria in the sediment, it digests a large amount of methane from the seabed. Without it, methane concentrations on Earth would have risen a lot.
Then the current temperature may not be the 20 degrees Celsius we are now, it may become 200 degrees.
So how to measure it?
▲ In situ concentration of dissolved methane in sediment pore water
The traditional technique is to bring the sample back, so the job I do is to insert a probe into its different depths, you can get its spectrum, and then do our relevant quantitative analysis, you get its data.
Its methane concentration is 20 times different from that of ordinary conventional sampling, so is the methane concentration in global sediments undervalued by a factor of 20? I don't know. But at least it's vastly underestimated.
The entire reserve of methane, or its content, may also be underestimated on a global scale.
Sediment pore water is too complex, to give a simple example.
▲ Cold spring fluid
We do the fluid of the cold spring, and the water underneath is only about ten centimeters or a few centimeters thick. I also inserted my probe into it at different depths, so what did you find?
It is generally believed that the anaerobic oxidation of methane produces hydrogen sulfide gas and carbon dioxide, but we did not hit any hydrogen sulfide gas, but measured a lot of elemental sulfur.
In this way, the traditional understanding of the oxidation process of methane is subverted.
Therefore, in situ detection can subvert some of the traditional cognition based on sampling or other simulation techniques.
▲ High temperature "black chimney" hydrothermal fluid
Some of the main developments I have made recently are that I now dare to insert an optical probe into a system of three or four hundred degrees celsius and some black smoke.
This system is first of all high temperature, our technology to solve the optical lens in high temperature, high pressure, strong corrosion, turbid environment detection.
This technology may now be the only optical sensor in the world that can be inserted into a hydrothermal vent for in situ detection.
▲ Low temperature polar acidity (pH
We don't just do high-temperature hydrothermal fluids, there are "black chimneys" and "white chimneys".
Its temperature is not particularly high, I call it low temperature, but it also has 100 degrees, but its pH is particularly low.
You can imagine a concentrated sulfuric acid under the sea floor, and then I hit the probe down and found that the probe measured a lot of hydrogen in the data.
Hydrogen is a very important gas required for the transformation of life from inorganic to organic, or organic, so it may have a certain relationship with this origin of life in the deep sea.
There is nothing special about solids and liquids, there must be stones under the seabed, there must be seawater, so can you believe that there is gas under the seabed?
We measured the gases on the ocean floor, and it was impossible for them to leave that environment and bring them back to the surface.
▲ The presence of supercritical carbon dioxide in nature was found
In an article we recently published in the English edition of The Science Bulletin, we found for the first time in nature the presence of supercritical carbon dioxide in its natural state.
My dress is wool and needs dry cleaning, so what does the dry cleaner use? It is the use of supercritical carbon dioxide.
What are its features?
It has the characteristics of gaseous and liquid, it can first dissolve organic matter. When it becomes supercritical, the organic matter, that is, some of the organic matter and dirt on the clothes, is taken away.
Then when its temperature and pressure drop, it becomes gaseous, and it can be pumped back and reused, which is the principle of dry cleaning.
It also has a principle that the oil industry uses it as an organic solvent.
It can also perform various catalytic functions.
The environment in which supercritical carbon dioxide is formed requires more than 30 degrees and more than 70 atmospheres, which is impossible on our surface, only in the deep sea or deep ground.
We found the presence of such bubbles in this hydrothermal area.
You can't bring this bubble back because its temperature reaches about 90 degrees. We can only shoot our light down, then measure its composition, and find that it is exactly the same as the composition of supercritical carbon dioxide simulated in the laboratory.
This bubble also carries a lot of nitrogen in it, which is needed for the origin of life. Miller's discharge experiment, which is the production of amino acids, also requires nitrogen.
Hydrothermal systems have long been thought to be a possible explanation for the origin of life on Earth, but no large amounts of nitrogen have been found in it.
We found that supercritical carbon dioxide may have an enriching effect on nitrogen. In this way, we propose a new early origin of life on Earth, or a process of transformation from inorganic to organic.
So, the supercritical carbon dioxide that you dry clean your clothes may be related to life.
▲ The presence of gaseous water on the seafloor was found
We also found a gaseous water under the seabed, which is also more magical. If it is a gaseous thing, it will either become water or liquid after the temperature drops, or it will rise to the surface of the sea.
So why didn't it become liquid, didn't it rise?
It has an inverted lake.
You can imagine holding your big washbasin in your house to the bottom of the sea and then having a steaming steaming water vapor that fills your basin all the time, and that water vapor will keep supplying it with heat.
In this way, it forms the structure of an inverted lake.
The structure of this inverted lake is amazing, it first has gaseous water in it, so that our earth science, the phenomenon of water and gas separation, or phase separation, is moved from the depths of the seabed to the surface of the seabed.
In addition, this inverted basin will form a very flat mirror surface, which will inhibit the large amount of sulfide particles from erupting into the marine environment.
These sulfide particles accumulate in large quantities around the vent, and its impact on the surrounding marine environment is reduced.
Footprint of a Raman spectroscopic probe
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Where did this probe go?
▲ Footprints of Raman probes
It has gone to many hydrothermal areas, has divened more than 150 times, and followed several domestic and foreign robots down to almost all the hydrothermal and cold spring areas of the post-arc basins of the Pacific Ocean, as well as the hydrothermal areas of the southwest Indian Ocean.
▲ Paired with "Starfish"
We use the Discovery robot, which is the robot of our Institute of Oceanography of the Chinese Academy of Sciences, and the "Starfish" robot, which is the first 6,000-meter electric propulsion robot in our country.
We paired it up and did weather hydrates in the deep ocean, also known as synthetic experiments with combustible ice.
▲ Communicate with the "Sea Dragon"
We also communicate with the "Sea Dragon", which is also a robot, which is the robot of our country to conduct ocean research.
We followed the Sea Dragon to the Southwest Indian Ocean, and then did various exploration work on the mid-ocean ridge.
▲ Explore the sea with the "dragon"
We are also exploring the sea with jiaolong, which is the deepest manned submersible in our country, or the world, to dive deeply.
We have carried it through joint testing and are expected to go to sea with it in September 2020.
▲ Out of the country
We've also gone abroad and worked with the United States to conduct in-situ exploration of all cold springs and hydrate zones along the west coast of the United States and Canada.
Move the lab to the bottom of the sea
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I didn't move the lab to the bottom of the sea, I just went to the sea with my probe, so how to build a laboratory on the seabed?
We've been exploring since 2016, and I've called it the Eye of the Ocean, staring at the bottom of the sea like an eye, not long, just a year.
▲ Eye of the Ocean-I
In the picture, we can see that there are huge changes in the ecological community of cold springs. You can see that the submarine shrimp from scratch, from the more to the more, less.
The experiment I did was a synthesis experiment of hydrates, and I found that the change in salinity was particularly large at 375 days.
In June 2020, we conducted a scientific expedition at a time when the epidemic was more serious and overcame various difficulties.
We put the third generation system into the sea, this system is particularly complex, there are 7 light-resistant ballast chambers, equipped with various sensors and then conducted a related experiment.
▲ Eye of the Sea-III
It's not that I'm just looking at things in the deep, it's about doing all kinds of experiments in the deep.
But there is no Raman system in it, there is no system of various spectra, more electrochemical sensors and ordinary optical images.
What is my dream for the future?
It is to establish a laboratory of spectroscopy in the deep sea.
This laboratory not only uses the Raman probe or Raman spectroscopy I just talked about, but also puts the deep-sea laser-induced breakdown spectroscopy, fluorescence spectroscopy, infrared spectroscopy, all of which are placed on the seabed.
Why? Go observe the changes in the oceans, do some experiments.
What are the benefits? Because it is light, it will not destroy the environment in which those creatures live, I only need to hit a beam of light to get the information I need.
The realization of this dream is inseparable from the increasingly strong scientific research strength of our country.
This is our Science research vessel, which I have been working on for almost 8 years.
It's like a mother ship, or like our mother ship, that can lead us to all kinds of deep-sea experiments.
I hope that in the future, or when you are engaged in scientific research in the future, you can join the ocean and explore the deep sea.
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