Question 1

Because groundwater flow rates are often slow,groundwater pollution may first be detected many years after the occurrence of contamination and in areas distant from the pollution source.

Accepted Answer

Groundwater flow rates can be slow, which means it can take a long time for pollution to travel through the underground aquifer and be detected. Additionally, contaminants can sometimes spread far from the source due to the movement of groundwater, making it challenging to identify and clean up polluted areas.

Question 2

Given the quantitative definition of residence time,the effect of increasing the rate of input of a chemical into a natural system at equilibrium would be to increase the chemical's residence time.

Accepted Answer

Increasing the rate of input of a chemical into a system at equilibrium would likely decrease the residence time, as the system adjusts to remove the excess chemical more quickly to maintain equilibrium.

Question 3

The escape of nutrients from sediments can be reduced or eliminated by any of the following strategies except

Accepted Answer

The answer of The escape of nutrients from sediments can...

Question 4

Water containing an abundance of nutrients,which encourages lush growth of such plants as algae is termed

Accepted Answer

The term that describes water with an abundance of nutrients that encourages lush growth of algae and other plants is eutrophic. This often leads to an imbalance in the ecosystem and can harm aquatic organisms. None of the other options accurately describe this phenomenon.

Question 5

Which of the following statements is not true?

Accepted Answer

A body of water described as "dead" does not necessarily have to contain fatal concentrations of toxic chemicals. It can also refer to a body of water that has been depleted of oxygen due to excessive organic pollution.

Question 6

Dumping lawn clippings into a stream will reduce this

Accepted Answer

Dumping lawn clippings into a stream increases organic matter, which decomposes and consumes dissolved oxygen, reducing its levels in the water.

Question 7

What develops as a result of migration of the pollutant by groundwater that forms down-gradient with reference to the point source

Accepted Answer

Migration of the pollutant by groundwater forms a contaminant plume, which spreads downstream or down-gradient from the point source. This occurs due to the movement of contaminated water through the permeable soil or rock layers. A contaminant plume defines a concentration gradient where the concentration of the pollutant decreases with distance from the point source. Therefore, option D, Contaminant plume, is the correct answer. Options A, B, and C do not adequately describe the phenomenon of pollutant migration by groundwater.

Question 8

Ground water contaminated with acid rain percolates through a limestone aquifer.With longer residence time in the aquifer system,

Accepted Answer

Limestone is a sedimentary rock composed mainly of calcium carbonate, which can neutralize the acidity in the groundwater. As the water flows through the limestone, it will dissolve some of the rock, increasing the dissolved bicarbonate concentration. Sulfate and nitrate are not directly affected by the limestone and may remain in the water or even decrease as they are adsorbed onto the limestone surface. Therefore, option C is the correct choice.

Question 9

The pump-and-treat method is

Accepted Answer

The pump-and-treat method involves pumping polluted groundwater from an aquifer to the surface for treatment before it can be returned to the aquifer. This method is commonly used to remediate groundwater contaminated by hazardous waste and other pollutants. It is not a fast, effective or inexpensive method, but it can be effective in cleansing contaminated water well enough to be used as a drinking water supply.

Question 10

Pump and treat technique is used for reversing the damage for

Accepted Answer

The pump and treat technique is commonly used for groundwater remediation, where contaminated groundwater is extracted from the ground and treated before it is released back into the environment. This technique is not typically used for reversing damage in streams, lakes, or estuaries.

Question 11

Use of microorganisms to break down toxic organic compounds in ground water is called

Accepted Answer

Bioremediation is the process of using microorganisms to break down toxic organic compounds in ground water. Aerobic and anaerobic decay refer to the breakdown of organic material in the presence or absence of oxygen, respectively. Eutrophication is the process of excessive nutrient loading in bodies of water leading to an overgrowth of algae and depletion of oxygen.

Question 12

Naturally occurring concentrations of some toxic elements,such as arsenic,may exceed both recommended "safe" levels and wastewater standards for industry.

Accepted Answer

This is true. Naturally occurring concentrations of some toxic elements, such as arsenic, may be above recommended safe levels and wastewater standards for industry. This is due to geological factors and can vary by location.

Question 13

Groundwater pollution in situ is commonly handled by

Accepted Answer

Waiting for the pollutants to disperse or break down is the best choice for handling groundwater pollution in situ as it allows for natural remediation processes to occur. This method is often more cost-effective and less disruptive to the environment than other methods such as chemical decontamination or aeration. However, it is important to monitor the site to ensure that the pollutants are indeed dispersing or breaking down over time.

Question 14

Nonpoint pollution sources are more diffuse and thus harder to monitor and control than are most point sources.

Accepted Answer

Nonpoint sources of pollution include runoff from agricultural fields, parking lots, and urban streets. Because the sources are often widely distributed, it can be difficult to monitor and control them compared to more concentrated point sources such as industrial discharges or sewage treatment plants.

Question 15

The threat posed by some synthetic chemicals is difficult to assess because of lack of knowledge of their residence times in natural systems.

Accepted Answer

Synthetic chemicals can persist for a long time in natural systems, and their effects can be difficult to predict since their residence times in different environments are not well understood.

Question 16

Dredging of a lake bottom

Accepted Answer

All of the choices are correct. Dredging can remove toxic pollutants from sediment particles, but can also cause sediment pollution and reduce nutrient recycling from sediments. Therefore, all the choices are correct.

Question 17

A factory illegally dumps arsenic-rich wastewater into a lake,where the residence time of the arsenic is 10 years.If the dumping stops,after 30 years,the amount of arsenic in the lake will be one-third what it was when the dumping was stopped.

Accepted Answer

The amount of arsenic in the lake will not decrease to one-third of its original level after 30 years, even if the dumping stops. This is because the residence time of arsenic in the lake is 10 years, meaning it takes 10 years for half of the arsenic to be removed through natural processes. After 30 years without further arsenic dumping, only one-eighth (2^-3) of the original amount of arsenic would remain in the lake.

Question 18

Biochemical oxygen demand is the amount of oxygen needed

Accepted Answer

Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms to break down organic matter present in a given water sample at a certain temperature over a specific time period. The higher the BOD level, the greater the organic load or pollution in the water. Therefore, option C is the correct choice as it describes the oxygen demand for the breakdown of organic matter.

Question 19

Eutrophication of water is accelerated by

Accepted Answer

Increased sediment load from erosion contributes to eutrophication by adding excess nutrients, such as nitrogen and phosphorus, to the water which can promote the growth of algae and other aquatic plants. This excess plant growth can lead to decreased oxygen levels in the water and negatively impact other aquatic organisms. Addition of oxygen, reduction in phosphate input, and reduction in nitrate input are not factors that accelerate eutrophication.

Question 20

Concern about environmental pollution is such that comprehensive health hazard information has now been determined for most synthetic drugs and agricultural and industrial chemicals.

Accepted Answer

While there has been significant progress in understanding the environmental and health impacts of various substances, comprehensive health hazard information is not yet available for most synthetic drugs and agricultural and industrial chemicals due to the vast number of chemicals in use and the complexity of their interactions with the environment and human health.

Quiz 17: Water Pollution