VOA标准英语2010年-Computer Model Helps Minimize Water Po

The US Environmental Protection Agency lists stormwater as the primary cause of water pollution in the United States.

Roads, shopping centers and housing developments are generally seen as enhancing a community's quality of life. But they can also disrupt the delicate water cycle that provides food, recreation and hydration to communities.

 When rain and melting snows flow over a city's streets, parking lots and sidewalks, that runoff picks up all kinds of pollutants¹ such as residues² of petroleum³ and pesticides⁴, soaps and solvents⁵, as well as pet and wildlife waste.

Too often, the run-off spills directly into local waterways. The U.S. Environmental Protection Agency, or EPA, lists stormwater as the primary cause of water pollution in the United States, and encourages local communities to develop management plans to treat run-off before it pollutes their rivers, lakes or streams.

Easy to use computer model

Bill Hunt, a professor of Biology and Agricultural Engineering at North Carolina State University, has developed an easy-to-use computer model to predict how landscape impacts water pollution.

"There are different ways of evaluating how well stormwater practices clean water … things like ponds and wetlands and permeable pavement."

The program asks users - developers or state regulators, for example - to enter a description of the local land types, such as parking lots, rooftops, roads, grasses or woods, along with any water treatment areas.

"This model essentially⁶ assesses how well (stormwater practices) work in a new way. And it's a break from the way states have done it previously⁷."

Communities across the U.S. have become more aware of the dangers of untreated stormwater. Hunt's computer program gives them a useful new tool for addressing the problem.

The model works by using a relatively⁸ new understanding of the water filtration process. Engineers have found that wetlands, grassy⁹ fields and soil or sand filters can take in stormwater with different levels of pollution and release water with a relatively constant cleanliness. One important factor affecting the water quality is the area's temperature and rainfall, and Hunt's model is set up for the mid-Atlantic region of the United States. However, Hunt says the principles can easily be applied¹⁰ to other temperate¹¹ climates.

Nitrogen and phosphorous

To encourage widespread use among land design firms and regulators, Hunt kept his computer model simple. It uses average yearly data in its computations, and focuses on only two major pollutants - nitrogen and phosphorous.

"If you have an imbalance, or literally¹² too much nitrogen and too much phosphorous getting into those systems, you can essentially deplete¹³ the oxygen in that water. Which, in the end, without oxygen you have fish kills, and the like."

Phosphorous from detergents¹⁴ often contaminates urban stormwater, while nitrogen comes primarily from fertilizer use in agricultural areas. According to Ben Urbonas, president of the Urban Watersheds¹⁵ Research Institute, these nutrient¹⁶ contaminants tend to be more of a problem in closed water systems, like lakes, where concentrations can build up.

Wastewater first, then stormwater

In developing countries, the main source of water pollution is not stormwater, but waste water. Urbonas says communities there must focus first on developing a proper wastewater treatment system, using more complex models to plan collection and treatment.

"I think the priorities are totally skewed when people start looking at stormwater when in reality they need to be looking at what is the primary biggest culprit in what their receiving waters are being degraded by."

While many developing-world communities might not be ready for Hunt's runoff management model, Urbonas believes it is important for them to be aware of the pollutants present in stormwater even as they learn to manage their community's waste water.

A small community of design firms and regulators in North Carolina is currently testing the model, and after this trial period, it will be available free to the public on Bill Hunt's university faculty¹⁷ webpage.

 

1 pollutants   

污染物质（尤指工业废物）( pollutant的名词复数 )

参考例句：

• Pollutants are constantly being released into the atmosphere. 污染物质正在不断地被排放到大气中去。
• The 1987 Amendments limit 301(g) discharges to a few well-studied nonconventional pollutants. 1987年的修正案把第301条（g）的普通排放限制施加在一些认真研究过的几种非常规污染物上。 来自英汉非文学 - 环境法 - 环境法

2 residues   

n.剩余，余渣( residue的名词复数 )；剩余财产；剩数

参考例句：

• pesticide residues in fruit and vegetables 残留在水果和蔬菜中的杀虫剂
• All organic and metallic residues on the wafers must be removed. 片子上所有的有机和金属残留物均必须清除。 来自辞典例句

3 petroleum   

n.原油，石油

参考例句：

• The Government of Iran advanced the price of petroleum last week.上星期伊朗政府提高了石油价格。
• The purpose of oil refinery is to refine crude petroleum.炼油厂的主要工作是提炼原油。

4 pesticides   

n.杀虫剂( pesticide的名词复数 )；除害药物

参考例句：

• vegetables grown without the use of pesticides 未用杀虫剂种植的蔬菜
• There is a lot of concern over the amount of herbicides and pesticides used in farming. 人们对农业上灭草剂和杀虫剂的用量非常担忧。 来自《简明英汉词典》

5 solvents   

溶解的，溶剂

参考例句：

• It is resistant to borohydride reduction in alcoholic solvents. 在醇溶剂中，它不能被硼氢化物还原。
• Strains require special treatments for removal such as spotting with organic solvents. 要清除这些着色物质，需要特殊处理，例如：滴加有机溶剂。

6 essentially   

adv.本质上，实质上，基本上

参考例句：

• Really great men are essentially modest.真正的伟人大都很谦虚。
• She is an essentially selfish person.她本质上是个自私自利的人。

7 previously   

adv.以前，先前（地）

参考例句：

• The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
• Let me digress for a moment and explain what had happened previously.让我岔开一会儿，解释原先发生了什么。

8 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

9 grassy   

adj.盖满草的；长满草的

参考例句：

• They sat and had their lunch on a grassy hillside.他们坐在长满草的山坡上吃午饭。
• Cattle move freely across the grassy plain.牛群自由自在地走过草原。

10 applied   

adj.应用的；v.应用，适用

参考例句：

• She plans to take a course in applied linguistics.她打算学习应用语言学课程。
• This cream is best applied to the face at night.这种乳霜最好晚上擦脸用。

11 temperate   

adj.温和的，温带的，自我克制的，不过分的

参考例句：

• Asia extends across the frigid,temperate and tropical zones.亚洲地跨寒、温、热三带。
• Great Britain has a temperate climate.英国气候温和。

12 literally   

adv.照字面意义，逐字地；确实

参考例句：

• He translated the passage literally.他逐字逐句地翻译这段文字。
• Sometimes she would not sit down till she was literally faint.有时候，她不走到真正要昏厥了，决不肯坐下来。

13 deplete   

v.弄空，排除，减轻，减少...体液，放去...的血

参考例句：

• Most native mammal species have been severely depleted.大多数本地哺乳动物的数量都已经大大减少了。
• Elastic collisions deplete very little of the electron's energy.弹性碰撞中电子减少的能量非常少。

14 detergents   

n.洗涤剂( detergent的名词复数 )

参考例句：

• Such detergents do not yellow the wool as alkali tends to do. 这种洗涤剂不会象碱那样使羊毛发黄。 来自辞典例句
• Development of detergents has required optimization of the surfactants structure. 发展洗涤剂时，要求使用最恰当的表面活性剂结构。 来自辞典例句

15 watersheds   

n.分水岭( watershed的名词复数 )；分水线；转折点；流域

参考例句：

• Hyetographs are important in estimating stormflow hydrographs from upstream watersheds. 降雨历线资料为上游集水区推估洪水流量历线的重要依据。 来自互联网
• Sediments check dam in small watersheds in loess hilly gully area come from three proportion, i. 黄土丘陵沟壑区治沟骨干工程泥沙淤积来源于坡面侵蚀、沟道侵蚀和库区岸坡坍塌。 来自互联网

16 nutrient   

adj.营养的，滋养的；n.营养物，营养品

参考例句：

• Magnesium is the nutrient element in plant growth.镁是植物生长的营养要素。
• The roots transmit moisture and nutrient to the trunk and branches.根将水分和养料输送到干和枝。

17 faculty   

n.才能；学院，系；(学院或系的)全体教学人员

参考例句：

• He has a great faculty for learning foreign languages.他有学习外语的天赋。
• He has the faculty of saying the right thing at the right time.他有在恰当的时候说恰当的话的才智。