【推荐1】For many of us，summertime means road trips to the beach or mountains，or at the very least some additional dust and bird poop on the exterior of our vehicles.The extra dirt leads us to do one of two things：wash our car in the driveway or head to the car wash.But which choice is better for the environment?

The main concerns with either choice are the amount of fresh water being used and the types of chemicals used to remove the dirt.Both of these concerns can be closely monitored when washing the car at home，says Katy Gresh，spokeswoman for the Southwest Region of the Pennsylvania Department of Environmental Protection.She advises car owners to put aside a set amount of water for the entire wash.“It’s just like brushing your teeth，”she says.“You don’t want to leave the water running or use more than you need for the job.” But even following this advice comes with an environmental risk：Washing your car in the driveway or street flushes the dirty water into storm drains.

John Schombert is executive director of 3 Rivers Wet Weather.His organization works to educate the public about storm sewers(下水道) and water runoff，keeping this untreated water from entering the Allegheny region’s waterways.“We ask people to consider washing their cars on lawns or other permeable(透水的) surfaces where the water gets absorbed，”Schombert says.“Soil can break down and help filter(过滤) those things，”Schombert says.“Storm sewers are not made for waste disposal.”Even when car owners use natural soaps to wash their cars，which Schombert says are probably ineffective at breaking down grease anyway.

The commercial car wash down the street knows full well the rules regarding wastewater in storm sewers.According to the International Carwash Association(ICA)，professional car washes must use water reclamation systems.These mandated processes not only keep the dirty water out of storm sewers and regular water treatment systems，but they also work to reduce water usage at commercial facilities.

【推荐3】They give us paper and fuel, as well as vital ecological services — like cleaning the air, storing carbon and providing habitat. We’re talking about trees, of course. But changes in the environment largely caused by humans appear to be causing great transformations in trees around the world.

In a new study, scientists reviewed global research on trends in tree seedlings, growth and death. They combined those data with an analysis of deforestation (森林砍伐). And they found that worldwide, older trees are dying at a higher rate than in the past due to factors like rising air temperature, wildfires, drought and pathogens (病原体).

“And most of the drivers of this decrease in large, old trees, such as rising temperatures, severe droughts, wildfires, windstorms and deforestation are all — although variable across the globe — generally increasing. And so both the loss has already occurred, but we expect more continued loss of big, old trees,” said Nate McDowell, an earth scientist at Pacific Northwest National Lab, who was one of the study’s authors.

“So if we have an increasing rate of death, particularly of the larger, older trees, what’s left are the younger trees. So that’s why, on average, through the loss of bigger, older trees, our forests are becoming younger and shorter.”

This trend is a problem because old trees are vitally important. “For sure, the increase in death does limit the carbon storage of an ecosystem and can force the system to become a carbon source to the atmosphere. The second reason we care is from a biodiversity perspective: Old trees tend to house a higher biodiversity than young forests do. And the third reason is linked with beauty: As a society, we care about these trees. We have national parks named after these big trees. So there’s a personal reason for people to care about this as well,” McDowell added.

【推荐1】Scientists say they have found high levels of small plastic particles （颗粒）in Arctic snow. Their findings provide more evidence that plastic is entering Earth's atmosphere and traveling great distances around the planet.

A German-Swiss research team collected snow samples from the Arctic and other areas. They included northern Germany, the Bavarian and Swiss Alps, and the North Sea island of Heligoland. When the researchers examined the samples in a lab, they were surprised to find very high levels of microplastics.

Microplastics are very small pieces of plastic. These plastic particles are generally smaller than 5 millimeters in length. Other studies have found microplastics in the environment. They come from the disposal and breakdown of man-made plastic products and industrial waste.

The study found the highest levels of microplastics came from the Bavarian Alps. One snow sample （标 本）from the area had 154,000 microplastic particles per liter. Samples collected from the Arctic had much lower levels. However, even samples from the Arctic contained up to 14,000 particles per liter.

Earlier studies found signs of plastic in Arctic areas. Those microplastics were found in coastal areas, sea ice, the seafloor and the seawater's surface. The new study attempted to explore how some of the material could have been carried in the atmosphere. A limited number of earlier studies did find microplastics in the air of some cities, including Paris, Tehran and Dongguan, China.

The research team discovered many kinds of microplastics. Some were from paints commonly used to coat the surface of automobiles and ships. A rubber-like substance was also found that could have come from vehicle or boat parts or packaging materials.

While there is growing concern about the effect of microplastics on the environment, scientists are still studying their possible harmful effects on humans and animals.

【推荐3】Elements of Latin have made their way into many western countries. Data varies, but as much as 70% of words in English have a Latin or Greek root. By learning more about these roots and how they combine (结合) to create words, you will have an advantage in understanding new words, even if you’ve never seen them before.

The great thing is that you’re not learning the whole language with its grammar. You just need to memorize some parts of the vocabulary that you often see in English. So how do word roots work?

Every word has a root. This part contains the key to a word’s meaning. Take the word “happy”, for example. This word only contains the root, which means full of joy. Some words, however, have extra parts. We call these affixes (词缀), including prefixes, the part attached before the root, and suffixes, the part attached behind the root. Based on the additional meaning of the prefixes and suffixes, the meaning of the final word will be shaped to mean something new.

Take the word “autobiography” for example. The root is “bio”, meaning life. You may have noticed that many words with “bio” have something to do with life or living beings—biology, biography, and so on. When the suffixes “graph”, meaning to write, is added to it, it means a story about someone’s or something’s life. “Auto” means by oneself. Altogether, an “autobiography” is a story about a person’s life, written by the person himself or herself.

In a word, a better grasp of word roots can make you understand the English language better, and will help you with your vocabulary recognition and memory skills.