World leaders at the 5th meeting of the United Nations Environment Assembly (UNEA) agreed that by 2024, they would create and sign a new treaty on plastics. The new treaty would create international laws     1     could help bring plastic waste under control.

Because plastic is useful for so many purposes, it has become a part of nearly all areas of our lives. It’s hard to look anywhere without finding dozens of     2     (object) made of plastic.

The United Nations Environment Program (UNEP) reports that     3     (current) 400 million tons of plastic is produced every year. By 2040, that number is predicted to double. And even though there’s a lot of talk about recycling, only 9% of all the plastic ever     4     ( produce) has been recycled.

Plastic gives off dangerous gases when it’s made and also when it’s burned or buried in the ground. Scientists say plastics are responsible     5     4.5% of the world’s greenhouse gases — the gases that are driving the climate crisis.

Plastic doesn’t “decompose (腐烂)” like natural materials. Instead, it just breaks into smaller and smaller pieces. And as the plastics     6     (fill) our world break down, they create     7     new problem — microplastics.

Microplastics are so tiny that     8     (they) existence is usually ignored. In the past few years, microplastics     9     (find) almost everywhere, from the North pole to Antarctica, from the top of the Earth’s     10     (high) mountain to the deepest point in the sea. They’ve even appeared in the bodies of animals including humans.

5 . What is the Great Pacific Garbage Patch?

The Great Pacific Garbage Patch (GPGP) is the largest of the five offshore plastic accumulation zones in the world’s oceans. It is located halfway between Hawaii and California.

PLASTIC __________

It is estimated that 1.15 to 2.41 million tonnes of plastic are entering the ocean each year from rivers. More than half of this plastic is less __________than the water, meaning that it will not sink once it encounters the sea.

The strong and floating plastics show resiliency(韧性) in the marine environment, allowing them to be transported over __________distances. They persist at the sea surface as they make their way off shore, transported by converging (汇聚的) currents and finally accumulating in the patch.

Once these plastics enter the gyre（环流）, they are unlikely to leave the area until they __________into smaller microplastics under the effects of sun, waves and marine life. As more and more plastics are discarded into the environment, microplastic __________in the GPGP will only continue to increase.

LOCATION

Due to seasonal and interannual variabilities of winds and currents, the GPGP’s location and shape are constantly changing. Only floating objects that are __________influenced by currents were likely to remain within the patch.

By simulating concentration levels in the North Pacific, the researchers were able to follow the location of the patch and found on average it orbits around 32°N and 145°W. However, the team observed seasonal __________from west to east and substantial variations in latitude（纬度）depending on the year.

IMPACT ON WILDLIFE

Plastic has increasingly become a very common substance in the ocean. Due to its size and color, animals __________the plastic for food, causing malnutrition; it poses entanglement（缠绕）risks and threatens their overall behavior, health, and existence.

Studies have shown that about 700 species have encountered marine debris, and 92% of these __________are with plastic. 17% of the species affected by plastic are on the International Union for Conservation of Nature Red List of Threatened Species.

IMPACT ON HUMANS AND SOCIETY

Once plastic enters the marine food web, there is a possibility that it will contaminate the human food chain as well. Through a process called bioaccumulation, chemicals in plastics will enter the body of the animal __________on the plastic, and as the feeder becomes prey, the chemicals will pass to the __________—making their way up the food web that includes humans. These chemicals that affected the plastic feeders could then be __________within the human as well.

__________, yearly economic costs due to marine plastic are estimated to be between $6-19billion USD. The costs __________its impact on tourism, fisheries and aquaculture, and governmental cleanups. These costs do not include the impact on human health and the marine ecosystem due to __________research available.

8 . Microplastic pollution has been detected in human blood for the first time, with scientists finding the tiny particles(微粒) in almost 80% of the people tested. The discovery shows the particles can travel around the body and may live in organs.

The impact on health is as yet unknown. But researchers are concerned as microplastics cause damage to human cells in the laboratory and air pollution particles are already known to enter the body and cause millions of early deaths a year.

Huge amounts of plastic waste are left in the environment and microplastics now pollute the entire planet, from the top of Mount Everest to the deepest oceans. People were already known to consume the tiny particles via food and water as well as breathing them in, and they have been found in the faeces (排泄物) of babies and adults.

The scientists analysed blood samples from 22 healthy adults and found plastic particles in 17. Half the samples contained PET plastic, which is commonly used in drinks bottles, while a third contained polystyrene, used for packaging food and other products. A quarter of the blood samples contained polyethylene, from which plastic carrier bags are made.

“Our study is the first indication that we have polymer particles(聚合物颗粒) in our blood — it’s a breakthrough result,” said Prof Dick Vethaak, an expert at Vrije Universiteit Amsterdam in the Netherlands. “But we have to extend the research and increase the sample sizes, the number of polymers assessed, etc.” Further studies by a number of groups are already under way, he said.

“It is certainly reasonable to be concerned,” Vethaak said. “The particles are there and are transported throughout the body.” He said previous work had shown that microplastics were 10 times higher in the faeces of babies compared with adults and that babies fed with

Vethaak acknowledged that the amount and type of plastic varied considerably between the blood samples. “But this is a pioneering study,” he said, with more work now needed. He said the differences might reflect short-term exposure before the blood samples were taken, such as drinking from a plastic-lined coffee cup, or wearing a plastic face mask.

“The big question is what is happening in our body?” Vethaak said. “Are the particles retained in the body? Are they transported to certain organs, such as getting past the blood-brain barrier? And are these levels sufficiently high to cause disease? We urgently need to fund further research so we can find out.”

9 . Microplastics —   tiny pieces of plastic waste less than five millimetres long that have been degraded by waves, wind and ultraviolet rays — have been discovered in the deepest oceanic trenches and within the stomachs of the organisms that live there, but we have little idea about where the great majority of them end up. More than eight million tonnes of plastic enters our oceans every year, comprising between 80 and 85 percent of all marine trash, but with inadequate data, there are concerns that these figures could be underestimates.

Currently, most of the data we have on microplastics are accidentally captured by research ships, which use plankton nets to collect marine-microorganism samples. However, researchers Christopher Ruf and Madeline Evans from the University of Michigan have discovered an innovative way to identify and track concentrations of microplastics in the ocean.

The technique relies on NASA’s Cyclone Global Navigation Satellite System (CYGNSS), a constellation of eight micro-satellites used to predict hurricanes that calculate wind speeds above the ocean by measuring the roughness of surface waters. As the satellites are continuously recording, Ruf and Evans realised that they collect a great deal of additional data. It was while analysing these data that they noticed some differences-times where the surface of the ocean appeared to be much smoother than it should, given the prevailing wind (盛行风) conditions.

Knowing that water isn’t roughened as much when it contains a lot of floating material, Ruf and Evans identified a pattern that linked areas of unusual smoothness and predicted microplastic distributions. They found that the difference between their measurements, and how much rougher the surface would be if winds of the same speed were blowing across clear water, was “highly correlated with the presence of microplastics, and the degree of the difference also correlated with the concentration of the plastics.”

The research reveals that there are seasonal variations,where the concentrations of microplastics tend to be higher in the summer and lower in the winter in a very clean, periodic way, which Ruf explains mirrors the way in which the ocean circulation changes throughout the year. It also confirms, as was previously thought, that rivers are the main source of ocean microplastics.

Raising awareness of the issue of ocean microplastics among the public and politicians is just one of the researchers’ future aims; they are also in conversation with Duteh non-profit The Ocean Cleanup and Finnish clean-technology specialist Clewat, which are interested in using the information to more efficiently target their trash-collection campaigns.

So far, only one year’s worth of data have been processed since CYGNSS was launched in 2016. By looking at a longer time period, Ruf and Evans aim to determine whether the seasonal pattern is repeatable, and whether the concentration of micmplastics in the ocean is getting worse.

10 . Flower scents (香味) help pollinators (传粉者) locate their favorite plants. Scientists have established that air pollutants change those scents, throwing off the tracking abilities of such beneficial insects as honeybees. But new lab experiments are the first to confirm that one pollinator, the tobacco hawkmoth, can quickly learn that a pollution-changed scent comes from the jasmine tobacco flower that the insect likes.

Chemical ecologist Markus Knaden and colleagues focused on one pollutant-ozone, the main element in smog. In the lab, his team blew an ozone-changed scent from a tiny tube into a tunnel, with a moth (飞蛾) awaiting at the far end of the tunnel. Usually, when the moth smells the unchanged scent, it flies upwind and uses its long, skinny mouthparts to probe the tube the way that it would a flower. The researchers expected that the changed scent might throw the moth off a little. But the insect wasn’t attracted at all.

In addition to scent, tobacco hawkmoths track flowers visually, so Knaden’s team used the feature, along with a sweet snack, to train the moth to be attracted to a pollution-changed scent. The researchers wrapped a brightly-colored artificial flower around the tube to trick the moth back across the tunnel, despite the unfamiliar scent. And the team added sugar water to the artificial flower. After a moth was given four minutes to taste the sweet stuff, it was attracted to the new smell when sent into the tunnel 15 minutes later, even when neither the sugar water nor the visual signal of the artificial flower was present.

This study focused on only one moth species, but Knaden’s team is now working on planning experiments with other pollinators that are easier to follow than tobacco hawknoths. While he guesses honeybees might also be as adaptable as the moth was, that won’t be true of every pollinator. “The situation can become very bad for insects that are not as clever or cannot see that well. I don’t want the take-home message to be that pollution is not a problem.”