Man-made "traces" on the seabed: Should mining sacrifice life on the seabed?

At the bottom of the Pacific Ocean hundreds of kilometers away from land, there are some strange signs that no animal can leave. Some are like narrow grooves cut in pale soil, and some are like paw prints, which were dug by a huge underwater monster in the deep-sea ecosystem.

In fact, these are all left by human beings. Humans have left countless traces on the earth's surface, but most of these long-standing excavation traces on the seabed are unknown. They are occasionally illuminated by the spotlight of the remote control submersible, but then they return to the darkness. They have existed for decades, just like the footprints left by astronauts on the moon, they are still clearly visible today, and nothing can wash them off.

In a picture taken a few years ago, we can see a 37-year-old excavation, and the following mark can be traced back to 1989. Similar marks can be traced back to 1970s and 1980s, and they are the first batch of scraps from deep-sea mining experiments. Ships equipped with dredgers and trenchers leave these wastes after operation and then leave.

Recently, scientists came back here with cameras and detectors to observe the changes in the ecosystem here-they found wounds that never completely healed. Soon, there will be more such excavations all over the ocean abyss, one of the last untouched wilderness on earth. What will future generations think of these marks? What will they say about human's pursuit of resources at the beginning of 2 1 century?

Where did the undersea digging mark come from?

In order to understand why there are these excavations and why they are so important, we need to dive into the prehistoric ocean. One day, a tooth fell from the shark's mouth and floated to the bottom of the sea hundreds of meters deep. Gradually, the metal precipitated from the seawater, forming a watery deposit, covering the teeth with a layer of minerals. Therefore, one of the slowest geological phenomena on earth-the growth of polymetallic nodules-began.

Not all polymetallic nodules start from teeth, some start from shells or bone fragments, or there is no inner core at all, but their similarity is that the growth rate is extremely slow. In millions of years, they can only grow a few centimeters. But as time goes on, they will become so rich that they cover a large area of deep-sea plains.

The Royal Navy Challenger discovered polymetallic nodules for the first time on its voyage 1873. The sailors dragged these nodules out of the water and crushed them with their hands like potatoes made of stone. They feel that the top seems smoother, but the bottom in contact with the surrounding sedimentary particles is rough, like pumice. Sailors may have smelled it, but these tuberculosis have no smell.

Chemists who participated in the Challenger expedition were among the first to notice that polymetallic nodules were not worthless. They are composed of "manganese peroxide", which is "one of the main substances for making bleaching powder", he wrote. In terms of material composition, polymetallic nodules are solidified by iron or manganese hydroxide and have a core, so they are also called manganese nodules. However, the remoteness of these nodules means that "they will never become a profitable resource". Obviously, chemists don't realize how important polymetallic nodules will be to deep-sea creatures and later humans.

A few years later, scientists found that these mycobacterium tuberculosis were like islands with some unique life forms. Their deep-sea plains cover 50% of the earth's surface-an unimaginable spectacular scale. If the ocean suddenly disappears, we will see that half of the earth is a vast desert composed of loose sediments. On this barren plain, polymetallic nodules provide a rare and solid surface for life. Some unique sponges and molluscs are fixed on it, and larvae of nematodes and crustaceans live in their gaps.

Daniel jones of ocean centre, Southampton, England, is mainly engaged in the research on the influence of human intervention on deep-sea creatures. He said: "They are like stony areas in the garden-there are more species living there than those living only in the soil."

In recent years, these tuberculosis have also attracted human attention, because many substances contained in them can be used to make smart phones. What the chemists who participated in the 1873 expedition didn't find was that manganese nodules also contain metal elements such as cobalt, nickel, copper, titanium and rare earth, which will bring great value to mankind one day. 2 1 century, with the rapid development of science and technology, there is an increasing demand for various metal materials, such as cobalt for lithium batteries. Lithium batteries have been widely used in automobiles and electronic products. At present, the problem is that the source of many metal materials is problematic, which involves the process of resource reserves and mining activities.

Therefore, these deep-sea polymetallic nodules have become more and more attractive targets, despite the huge engineering challenges in mining these nodules. For example, if all the nodules in the Clarion-Clipperton Zone (CCZ) in the northeast Pacific Ocean are mined and dried, the total amount will be conservatively estimated to reach 20 billion tons. For decades, mining these seabed minerals was considered uneconomical, but now, some mining organizations are taking action to mine polymetallic nodules and other types of seabed minerals. If their plan goes well, the seabed area excavated every year will reach hundreds of square kilometers.

What impact will such mining have? In the 1970s and 1980s, researchers and mining companies conducted preliminary experiments to evaluate the feasibility and environmental consequences of nodule mining. At different locations in CCZ and Ducorps proving ground near Peru, mining ships use special mechanical plows and rakes to level the Pacific Ocean floor, pick up nodules and drag them to the surface. Although this experiment does not fully simulate the mining machinery used in the future mining plan, and the scale is much smaller, the results are enough for us to understand the impact of mining on the seabed ecosystem.

Some excavations are left by scientists, who are curious about what will happen when an untouched ecosystem is excavated. Some emerging mining organizations will also leave traces of mining when testing mining technology, and even the CIA has left its own traces. Ocean Minerals Company (OMCO) is an industrial group alliance led by Lockheed Martin, which used Hughes Glomar Explorer for experimental mining. The ship later became famous for other reasons-in the 1960s and 1970s, in a secret salvage operation led by the Central Intelligence Agency, the ship carried a huge hook claw to salvage a Soviet submarine.

Impact on deep-sea creatures

Many years later, with the acceleration of deep-sea mining plan and the opening of exploration license, researchers returned to these sites in the Pacific Ocean and began to study the long-term effects of mining polymetallic nodules. They found that even after decades, life in these artificial trenches has not returned to normal.

On land, ploughed fields often germinate new life, but in the deep sea, these grooves are relatively barren. Organisms that used to rely on polymetallic nodules could not find the attachment surface after the nodules were removed. Others need to dig holes in soft sediments for food, but they cannot survive on the artificially compacted seabed surface. Lara Macheriotou of Ghent University in Belgium and his colleagues concluded in a paper published earlier this year: "In these deep-sea plains containing nodules, biological communities will be particularly vulnerable to the risk of extinction caused by mining nodules."

Researchers say that this effect may last for hundreds or even thousands of years. Sociologist Barbara? Adam once suggested that the world can be regarded as adjacent "time scenes", each with its own unique rhythm. According to her description, the time scale of industry or agriculture will move much faster than that of nature and ecology. All these time scales are intertwined, and when one of them is forced to advance at the pace of the other, long-term environmental damage will become a risk.

The time scale of the deep sea is slow and patient. Therefore, when humans send machines to the seabed to collect these minerals, two different time mechanisms collide: one is the rhythm of the deep sea, and the other is the desire for quickness and short-termism brought by new technologies.

On the earth, these deep-sea plains are the farthest from the lush terrestrial ecosystem and the accelerated development of human society. The temperature there is close to freezing point, the pressure is huge, and there is almost no light. Living creatures depend on "sea snow" to survive. The so-called sea snow refers to the organic debris that keeps settling like snowflakes in the deep sea. These fragments keep falling and are often digested by marine life three or four times.

"This is an environment with low temperature, low energy and lack of food, which often determines the rhythm of life," daniel jones said. "In shallow water, animals usually don't have extreme physiological changes. But here, any disturbance may last for a long time. "

Of course, compared with coral reefs in tropical shallow waters, these areas are like deserts in the ocean, but they are still important treasures of biodiversity and play a vital role in the carbon cycle through natural storage. Jones said, "We have seen many animals that are completely unfamiliar with science ... some creatures also have pharmaceutically active compounds." In the long run, these seabed areas may also interact with fisheries in the upper waters. "In some cases, the functions played by these communities may be of no value for centuries."

In this huge space, it is difficult for us to see life, because they are too small and scattered; We can't use photos to express the scale of this three-dimensional space. Unlike the scenes in the movies, there are no charming giant animals, but there are enough kinds of life, which cover half the earth after all.

Some people may think that in order to obtain valuable resources, destroying the deep-sea ecosystem is a worthwhile sacrifice. However, David Santillo of the Greenpeace Research Laboratory at the University of Exeter says that one mining method cannot simply replace another. Recently, he co-authored an overview of seabed mining and its potential impact on the forefront of marine science. He wrote: "This involves different companies, different markets, different demand-side pressures and incentive mechanisms to some extent ... So if seabed mining really begins to develop, it is more likely to become an auxiliary mine source."

Although it is difficult to quantify the importance of deep-sea creatures from the perspective of human morality or economy, they do have intrinsic value. As for those excavated traces, they will continue to exist for a long time, affecting the life of underwater creatures. Take the author of Footprints, David? In Farrier's words, these traces will eventually become "future fossils". He pointed out that in the Anthropocene, we are leaving all kinds of unnecessary industrial, chemical and geological relics, which will exist for centuries. "Future fossils are our heritage, so we have the opportunity to choose how we will be remembered," he wrote. "They will record whether we know that there is danger ahead, but we are still desperate to move on, or we care enough about the earth and choose to change direction. Our imprint will reveal to the living how we live, hint at what we cherish or ignore, as well as the road we have traveled and the direction we have chosen. "

These imprints are likely to be interpreted as one of the signs of our consumption habits at the beginning of 2 1 century. "If we have to destroy a large area of the seabed after running out of some minerals, it is undoubtedly a signal to re-examine how seriously we waste existing minerals," Santillo said. "If the ultimate goal of mining the seabed is to extend the unsustainable consumption pattern for another 30 years, or even accelerate this pattern by transporting more materials to the market ... then our future will not change."

Most people can't witness the vast deep sea world with their own eyes. Even today's deep-sea scientists use remote cameras instead of diving into the sea floor. No matter in space or time, the deep sea and the life in it are of unimaginable scale, and they are unaffected by events on land-it has been like this for thousands of years.

However, in the century we live in now, the situation may change; Humans may leave more than one or two gouges or piles of debris on the seabed. When researchers talk about human intervention in the deep sea, one word they often use is "interference". In scientific terms, this refers to the floating and diffusion of sediments and their effects on benthic biota; But the word has another meaning, and that is "irrational chaos". As a species that pursues rationality, we should be more cautious about the development of polymetallic nodules on the seabed. (Ren Tian)