1 . A new study by scientists at Utrecht University concludes that about half of global wastewater is treated, rather than the previous estimate of 20%. Despite this promising finding, the authors warn that treatment rates in developing countries are still very low.

Humans and factories produce vast quantities of wastewater per day. If not properly collected and treated, wastewater may severely threaten human health and pollute the environment.

The authors use national statistics to estimate volumes of wastewater production, collection, treatment and reuse. “Globally, about 359 billion cubic metres of wastewater is produced each year, equivalent to 144 million Olympic-sized swimming pools,” says Edward Jones, PhD researcher at Utrecht University. “About 48 percent of that water is currently released untreated. This is much lower than the frequently announced figure of 80%.”

While the results show a more optimistic outlook, the authors stress that many challenges still exist. “We see that particularly in the developing world, where most of the future population growth will likely occur, treatment rates are falling behind,” Jones explains. “In these countries, wastewater production is likely to rise at a faster pace than the current development of collection and treatment basic facilities. This poses serious threats to both human health and the environment.”

The main problem, especially in the developing world, is the lack of financial resources to build basic facilities to collect and treat wastewater. This is particularly the case for advanced treatment technologies, which can be extremely expensive. However, the authors highlight potential opportunities for creative reuse of wastewater streams that could help to finance improved wastewater treatment practices.

“The most obvious reuse of treated wastewater is to increase freshwater water supplies,” Jones states. Treated wastewater reuse is already an important source of irrigation water in many dry countries. However, only 11% of the wastewater produced globally is currently being reused, which shows large opportunities for expansion.

“But freshwater increasing is not the only opportunity,” says Jones. “Wastewater also has large potential as a source of nutrients and energy. Recognition of wastewater as a resource, opposed to as ‘waste’, will be the key to driving improved treatment going forward.”

However, the authors stress the importance of proper monitoring of wastewater treatment factories, accompanied by strong legislation (法律) and regulations, to ensure that the reuse of wastewater is safe. The authors also acknowledge public acceptance as another key barrier towards increasing wastewater reuse.

3 . Of all the weird and wonderful creatures living under the sea, perhaps the strangest are jellyfish—those rubbery, cone-shaped creatures found floating in the water, their long tentacles trailing behind.

Some jellyfish species have a bad reputation for scaring away tourists, clogging up fishing nets, and even blocking power station pipes. But with more and more plastic rubbish ending up in the sea, these days you’re as likely to swim into a plastic bag as a jellyfish. Now scientific research is discovering that these rubbery sea creatures might provide an answer—a sticky solution to the problem of plastic pollution.

In recent years, tiny pieces of plastic called microplastic have been a significant problem for the world’s seas and oceans. These plastics are not visible to the eye and aren’t caught by seawater treatment plants due to their small size, so they enter our system and harm our health. They’ve been found in many places—in Arctic ice, at the bottom of the sea and even inside animals. Slovenian scientist, Dr Ana Rotter, heads GoJelly, a European research team of jellyfish ecologists looking into the problem.

Microplastics, plastics in general, are becoming an increasing problem. Dr Ana Rotter says when she was a child, people were more environmentally friendly—not harmful to the environment or having the least possible impact on it. At that time, there were very few single-use plastics—plastic items, like spoons and forks, designed to be used just once, then thrown away. The situation since then has changed dramatically. In fact, there’s been such an increase in microplastics that today the UN lists plastic pollution as one of the world’s top environmental threats.

But how do jellyfish fit into the story? Well, it’s the ‘jelly’ part of jellyfish, and specifically their sticky, jelly-like mucus that is key. Jellyfish produce a thick, sticky liquid called mucus. Dr Ana Rotter has discovered that this mucus has strong absorptive capabilities—it can absorb, take in liquids and other substances. One of the substances jellyfish mucus absorbs are the particles that make up microplastics.

Dr Rotter’s research is still in the early stages, but it’s hoped that jellyfish mucus could hold the key to a future free of microplastic polluted oceans. Scientists are hoping that the mucus’s absorptive properties—its abilities to absorb liquids and other substances and hold them, will allow it to trap particles of plastic floating in the sea. By trapping these, the mucus acts like a magnet—an object that attracts certain materials, like metal, but in this case, microplastic waste.

4 . Human activity is changing the surface and temperature of the planet. But new research shows it is also changing the sound of the Earth’s oceans and seas.

Scientists say the changes in the sounds of our oceans and seas affect many marine(海洋) animals—from very small fish to huge whales. Sound travels “very far underwater,” Francis Juanes told the reporter. Juanes is an ecologist at the University of Victoria and co-writer of the recent research published in a magazine. “For fish,” he explained, “sound is probably a better way to sense their environment than light.”

Sounds help fish and other marine animals survive. They use sounds to communicate with each other. Sounds also help some ocean animals find food and avoid their hunters. Many ocean animals use sounds to find good places to give birth. However, increased noise from humans is making it harder for these animals to hear each other. The noise comes from shipping traffic, underwater oil and gas exploration, offshore construction, and other noisy human activity.

“For many marine species, their attempts to communicate are being masked by sounds that humans have produced,” said Duarte. The marine ecologist at the Red Sea Research Center co-wrote the paper with Juanes. The Red Sea, Duarte said, is one of the world’s most important shipping passages. It is full of large ships traveling to Asia, Europe, and Africa. Some fish and other animals, he said, now avoid the noisiest areas. Also, the overall number of marine animals has gone down by about half since 1970. In some parts of the ocean, scientists now record “fewer animals singing and calling than in the past—those voices are gone,” said Duarte.

Juanes and Duarte examined studies and research articles about changes in noise volume(音量) and frequency in the world’s oceans. Then they put together a detailed picture of how the ocean soundscape is changing and how marine life is affected.

Climate change, the researchers found, also affects physical processes that shape ocean sounds. These include such things as wind, waves, and melting ice.

Some studies suggest that noise may cause hearing loss of marine animals. Besides, many marine animals are showing higher levels of stress due to noise, which might also affect the immune(免疫) system.

Scientist Juanes says sound pollution may be easier to deal with than other ocean threats. “In theory,” he said, “you can turn down or turn off the sound immediately. It’s not like plastics or climate change, which are much harder to undo.”

It seems like common sense: eating local food should be better for the environment, because it     1     (transport) short distances.    2     (Unfortunate), it is not that simple. It is the production of food, not its transport, that uses most of the energy and     3     (produce)most of the greenhouse gases. In some cases, local produce might have used more energy and produced more greenhouse gases than produce grown a long way away—even taking into account its transport.