密歇根新闻广播 2014年微囊藻毒素恐慌之后,托莱多致力于恢复水质

Four years ago, the city of Toledo told more than 450,000 residents to immediately stop drinking water out of the tap.

That's after a toxin¹ called microcystin was detected in the water. The toxin came from a bloom of cyanobacteria that had surrounded the city's water intake² in Lake Erie.

The incident caused panic among some residents, hoarding³ of water, even fights at bottled water distribution sites - along with a lot of unwanted national media attention.

And it taught the city some hard lessons.

What happens to the water Toledo takes from Lake Erie

Municipal water treatment is a painstaking⁴ and complicated process.

Toledo's current water treatment plant was built in 1941, with multiple additions and updates over the years.

Inside the plant, it's humid and dark. Plant administrator⁵ Andrew McClure peers over the concrete side of a 20-foot deep channel, where 50,000 gallons of water a minute are flowing into the plant.

He says even at this early stage, the water has been partially⁶ treated, starting at the intake crib in Lake Erie.

"The water going through this channel has had potassium permanganate added, primarily for zebra mussel control, and powdered activated⁷ carbon for taste and odor and microcystin," McClure says.

Another chemical, aluminum⁸ sulfate, is added at this point. That gets all the microbes and other unwanted particles to coagulate or stick together.

"And then we go through a flocculation process to make floc and that's larger particles that actually settle out."

Flocculation involves passing the water through a fast and then slower churning. The chemicals mix thoroughly⁹ with the water, and the clumps¹⁰ of floc get bigger and heavier, so they can be removed later as sediment¹¹.

After flocculation, the plant adds lime, for softening¹², then sends the water to vast pools to pass through filters filled with sand and other materials.

Then the water's treated with chlorine and fluoride. Only after all this does the water leave the treatment plant.

Microcystin is detected and all heck breaks loose

Toledo had been testing for microcystin, a toxic¹³ by-product¹⁴ of cyanobacteria, only since about 2012. The U.S. EPA does not require the testing.

On August 1st, 2014, a routine weekly test detected a tiny amount of microcystin in the treated water -- 1.6 parts per billion, about the equivalent of a blade of grass in a football field. The microcystin came from a huge bloom of slimy green cyanobacteria that had surrounded the water intake in Lake Erie.

Janet Schroder is an analyst¹⁵ for Toledo public utilities. She says the detection put the city in a quandary¹⁶. The World Health Organization says a microcystin level of one part per billion is unsafe - but that's a lifetime exposure level. There's been little reseach on the risk to human health from acute or temporary exposures.

And the U.S. Environmental Protection Agency provided no guidance.

"Microcystin was not a regulated contaminant," she says. "It still is not a regulated contaminant."

Out of an abundance of caution, the city told residents to stop drinking the water. Administrator McClure says Toledo wasn't well prepared for what happened next.

"People fighting over bottled water, and the distribution of bottled water... the emergency response wasn't what it could have been."

At the time, it seemed like the right thing to do

After the Toledo crisis, the U.S. EPA decided¹⁷ 1.6 parts per billion of microcystin is not a public health crisis. The agency now gives utilities that are screening for microcystin more than a week to eliminate the toxin from treated water. The Ohio EPA has a shorter timeline, but the agency still does not require a do not drink advisory¹⁸ to be issued right away.

"Had rules been in place then, that are in place now, there would not have been a do not drink advisory," says McClure.

That's not to say the crisis was all for naught¹⁹.

Water systems all across the nation now have some idea what to do if it happens to them. In Michigan, communities that are monitoring for microcystin have had no incidents of detection in tap water.

And Toledo is determined²⁰ to avoid a repeat.

The water treatment plant tests for microcystin once a day during HAB (harmful algal bloom) season, typically from July through September.

New water quality monitoring buoys²¹ around the intake crib in Lake Erie send hourly reports of changing conditions in the water, including increasing levels of cyanobacteria.

The plant also built a new carbon storage system and increased its ability to treat the water with chemicals by a factor of four.

Utilities analyst Janet Schroeder says the city has also developed a better emergency response plan, including better public outreach. That includes a dashboard on the internet to show people the water is safe.

"In the event we have an emergency, everyone knows what's going on," she says.

Toledo's microcystin levels have been undetectable since 2014. But the work to restore trust is ongoing²². In the first couple of years after the incident, people would start rumors²³ on Facebook, sparking runs on bottled water. McClure says that behavior seems to be reducing in frequency.

A few people are still buying bottled water to drink, four years after the crisis, says Schroeder. She says it's not uncommon²⁴ for residents who go on public tours of the water treatment plant to express a willingness afterwards to start drinking the water from the tap.

So it could be a long time before people in Toledo take their drinking water for granted.

And maybe that's a good thing.

1 toxin   

n.毒素，毒质

参考例句：

• Experts have linked this condition to a build-up of toxins in the body.专家已把这一病症与体内毒素的积累联系起来。
• Tests showed increased levels of toxin in shellfish.检验表明水生有壳动物的毒素水平提高了。

2 intake   

n.吸入，纳入；进气口，入口

参考例句：

• Reduce your salt intake.减少盐的摄入量。
• There was a horrified intake of breath from every child.所有的孩子都害怕地倒抽了一口凉气。

3 hoarding   

n.贮藏；积蓄；临时围墙；囤积v.积蓄并储藏（某物）( hoard的现在分词 )

参考例句：

• After the war, they were shot for hoarding. 战后他们因囤积而被枪决。 来自《简明英汉词典》
• Actually he had two unused ones which he was hoarding up. 其实他还藏了两片没有用呢。 来自英汉文学

4 painstaking   

adj.苦干的；艰苦的，费力的，刻苦的

参考例句：

• She is not very clever but she is painstaking.她并不很聪明，但肯下苦功夫。
• Through years of our painstaking efforts,we have at last achieved what we have today.大家经过多少年的努力，才取得今天的成绩。

5 administrator   

n.经营管理者，行政官员

参考例句：

• The role of administrator absorbed much of Ben's energy.行政职务耗掉本很多精力。
• He has proved himself capable as administrator.他表现出管理才能。

6 partially   

adv.部分地，从某些方面讲

参考例句：

• The door was partially concealed by the drapes.门有一部分被门帘遮住了。
• The police managed to restore calm and the curfew was partially lifted.警方设法恢复了平静，宵禁部分解除。

7 activated   

adj. 激活的 动词activate的过去式和过去分词

参考例句：

• The canister is filled with activated charcoal.蒸气回收罐中充满了活性炭。

8 aluminum   

n.(aluminium)铝

参考例句：

• The aluminum sheets cannot be too much thicker than 0.04 inches.铝板厚度不能超过0.04英寸。
• During the launch phase,it would ride in a protective aluminum shell.在发射阶段，它盛在一只保护的铝壳里。

9 thoroughly   

adv.完全地，彻底地，十足地

参考例句：

• The soil must be thoroughly turned over before planting.一定要先把土地深翻一遍再下种。
• The soldiers have been thoroughly instructed in the care of their weapons.士兵们都系统地接受过保护武器的训练。

10 clumps   

n.（树、灌木、植物等的）丛、簇( clump的名词复数 )；（土、泥等）团；块；笨重的脚步声v.（树、灌木、植物等的）丛、簇( clump的第三人称单数 )；（土、泥等）团；块；笨重的脚步声

参考例句：

• These plants quickly form dense clumps. 这些植物很快形成了浓密的树丛。 来自《简明英汉词典》
• The bulbs were over. All that remained of them were clumps of brown leaves. 这些鳞茎死了，剩下的只是一丛丛的黃叶子。 来自《简明英汉词典》

11 sediment   

n.沉淀，沉渣，沉积(物)

参考例句：

• The sediment settled and the water was clear.杂质沉淀后，水变清了。
• Sediment begins to choke the channel's opening.沉积物开始淤塞河道口。

12 softening   

变软，软化

参考例句：

• Her eyes, softening, caressed his face. 她的眼光变得很温柔了。它们不住地爱抚他的脸。 来自汉英文学 - 家（1-26） - 家（1-26）
• He might think my brain was softening or something of the kind. 他也许会觉得我婆婆妈妈的，已经成了个软心肠的人了。

13 toxic   

adj.有毒的，因中毒引起的

参考例句：

• The factory had accidentally released a quantity of toxic waste into the sea.这家工厂意外泄漏大量有毒废物到海中。
• There is a risk that toxic chemicals might be blasted into the atmosphere.爆炸后有毒化学物质可能会进入大气层。

14 by-product   

n.副产品，附带产生的结果

参考例句：

• Freedom is the by-product of economic surplus.自由是经济盈余的副产品。
• The raw material for the tyre is a by-product of petrol refining.制造轮胎的原材料是提炼汽油时产生的一种副产品。

15 analyst   

n.分析家，化验员；心理分析学家

参考例句：

• What can you contribute to the position of a market analyst?你有什么技能可有助于市场分析员的职务？
• The analyst is required to interpolate values between standards.分析人员需要在这些标准中插入一些值。

16 quandary   

n.困惑，进迟两难之境

参考例句：

• I was in a quandary about whether to go.我当时正犹豫到底去不去。
• I was put in a great quandary.我陷于进退两难的窘境。

17 decided   

adj.决定了的，坚决的；明显的，明确的

参考例句：

• This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
• There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。

18 advisory   

adj.劝告的，忠告的，顾问的，提供咨询

参考例句：

• I have worked in an advisory capacity with many hospitals.我曾在多家医院做过顾问工作。
• He was appointed to the advisory committee last month.他上个月获任命为顾问委员会委员。

19 naught   

n.无，零 [=nought]

参考例句：

• He sets at naught every convention of society.他轻视所有的社会习俗。
• I hope that all your efforts won't go for naught.我希望你的努力不会毫无结果。

20 determined   

adj.坚定的；有决心的

参考例句：

• I have determined on going to Tibet after graduation.我已决定毕业后去西藏。
• He determined to view the rooms behind the office.他决定查看一下办公室后面的房间。

21 buoys   

n.浮标( buoy的名词复数 )；航标；救生圈；救生衣v.使浮起( buoy的第三人称单数 )；支持；为…设浮标；振奋…的精神

参考例句：

• The channel is marked by buoys. 航道有浮标表示。 来自《现代汉英综合大词典》
• Often they mark the path with buoys. 他们常常用浮标作为航道的标志。 来自辞典例句

22 ongoing   

adj.进行中的，前进的

参考例句：

• The problem is ongoing.这个问题尚未解决。
• The issues raised in the report relate directly to Age Concern's ongoing work in this area.报告中提出的问题与“关心老人”组织在这方面正在做的工作有直接的关系。

23 rumors   

n.传闻( rumor的名词复数 )；[古]名誉；咕哝；[古]喧嚷v.传闻( rumor的第三人称单数 )；[古]名誉；咕哝；[古]喧嚷

参考例句：

• Rumors have it that the school was burned down. 有谣言说学校给烧掉了。 来自《简明英汉词典》
• Rumors of a revolt were afloat. 叛变的谣言四起。 来自《简明英汉词典》

24 uncommon   

adj.罕见的，非凡的，不平常的

参考例句：

• Such attitudes were not at all uncommon thirty years ago.这些看法在30年前很常见。
• Phil has uncommon intelligence.菲尔智力超群。