VOA慢速英语2018--专家担心道路盐有害美国水质

Experts Worry That Road Salt Harms US Waters

Communities in the Northern parts of the United States have used salt to keep icy roads safe during winter for many years. But, some experts now say salt harms nearby fresh water supplies.

Putting salt on icy roads helps reduce traffic accidents and prevents people from slipping and falling on roads and walkways.

But researchers have found growing evidence that salt used on roads is increasing the salinity¹ in many lakes in the U.S.

Instead, they recommend using other materials such as beet² juice, molasses, or even waste products from making beer or cheese.

Victoria Kelly is a road salt expert at the Cary Institute of Ecosystem³ Studies in New York. She said scientists have been seeing increased amounts of salt in streams, rivers and lakes.

Now, she said, scientists are asking: “What is going to happen to the organisms living in freshwater bodies and what will happen to the freshwater bodies as a whole?”

New tools for keeping roads safe

Road salt is believed to have been first used in the 1940s in the state of New Hampshire. It became the main tool for removing ice from roads as cities expanded, highways were built and drivers began expecting clear roads.

It is estimated that more than 20 million tons of salt are used each winter in places like the Northeastern and Midwestern United States.

But many state and local agencies are looking for ways to reduce salt use because its harmful effects on the environment are becoming clearer.

Some agencies now use high-technology equipment to spread salt more effectively. Others are trying to study weather reports to make better decisions about when to use salt. Another new tool is liquid organic products that help salt stick to roads so it does not wash away easily.

For example, agencies in states such as New Jersey⁴ and North Dakota are using a mixture that includes beet juice to keep ice off of roads. New Hampshire and Maine use molasses. Highway departments also have used beer waste and pickle⁵ brine. In at least one county in Wisconsin, cheese brine was used.

Jonathan Rubin is director of the Margaret Chase Smith Policy Center in Maine. He is the lead author of a 2010 report on salting roads in the state.

“Adding salt to the environment does have negative impacts, but for those of us in the Northeast, especially in rural states, where driving is the predominant way of getting around, we need mobility,” said Rubin.

“In my opinion, we are always going to be using some degree of road salt,” he said. “The question is, can we use less?”

Leaving a salty taste in freshwater

Experts say salt corrosion⁶ already causes billions of dollars in damage each year to cars, roads and bridges. They also say there are growing signs that road salt is getting into freshwater.

In the past 50 years, chloride levels in some lakes and rivers are four times higher than normal. In a few cases, they are one hundred times higher.

Last year, a study in the Proceedings⁷ of the National Academy of Sciences found that more than 40 percent of the lakes studied showed long-term salinization.

The researchers estimated that by 2050, nearly 50 lakes in the study will have chloride levels that threaten freshwater plants and animals.

Other studies have shown that salinization of lakes and streams reduces the numbers of fish and amphibians⁸ and kills plants.

Caleb Dobbins is New Hampshire’s highway maintenance engineer. Although there are concerns, he does not think salt will be replaced anytime soon. Other chemicals, he notes, are more expensive than salt and have their own environmental risks.

I’m Phil Dierking.

Words in This Story

salinity - n. the amount of salt in something?

molasses - n. a thick, brown, sweet liquid that is made from raw sugar?

concentrations - n. a large amount of something in one place?

organic -adj. grown or made without the use of artificial chemicals?

brine - n. a mixture of salty water used especially to preserve or add flavor to food?

predominant - adj. more important, powerful, successful, or noticeable than other people or things?

corrosion - n. to slowly break apart and destroy (metal, an object, etc.) through a chemical process?

amphibians - n. an animal (such as a frog or toad) that can live both on land and in water

1 salinity   

n.盐分；咸度；盐浓度；咸性

参考例句：

• In the sea water sampled the salinity is two parts per thousand.在取样的海水中，盐度为千分之二。
• In many sedimentary basins the salinity of the formation water increases with depth or compaction.在许多沉积盆地中，地层水的含盐量随深度或压实作用而增高。

2 beet   

n.甜菜；甜菜根

参考例句：

• He farmed his pickers to work in the beet fields. 他出租他的摘棉工去甜菜地里干活。
• The sugar beet is an entirely different kind of plant.糖用甜菜是一种完全不同的作物。

3 ecosystem   

n.生态系统

参考例句：

• This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
• We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。

4 jersey   

n.运动衫

参考例句：

• He wears a cotton jersey when he plays football.他穿运动衫踢足球。
• They were dressed alike in blue jersey and knickers.他们穿着一致，都是蓝色的运动衫和灯笼短裤。

5 pickle   

n.腌汁，泡菜；v.腌，泡

参考例句：

• Mother used to pickle onions.妈妈过去常腌制洋葱。
• Meat can be preserved in pickle.肉可以保存在卤水里。

6 corrosion   

n.腐蚀，侵蚀；渐渐毁坏，渐衰

参考例句：

• Corrosion is not covered by the warranty.腐蚀不在保修范围之内。
• Zinc is used to protect other metals from corrosion.锌被用来保护其他金属不受腐蚀。

7 proceedings   

n.进程，过程，议程；诉讼(程序)；公报

参考例句：

• He was released on bail pending committal proceedings. 他交保获释正在候审。
• to initiate legal proceedings against sb 对某人提起诉讼

8 amphibians   

两栖动物( amphibian的名词复数 )； 水陆两用车； 水旱两生植物； 水陆两用飞行器

参考例句：

• The skin of amphibians is permeable to water. 两栖动物的皮肤是透水的。
• Two amphibians ferry them out over the sands. 两辆水陆两用车把他们渡过沙滩。