26 biogeochemical cycling

Which process produces a gaseous product that can be used as fuel to provide heat or power for a wastewater treatment plant?

anaerobic secondary wastewater treatment

Lignin is a complex polymer of methoxylated ________ compounds and is present in ________.

aromatic / vascular plant material

Water distribution systems contain

biofilms that may harbor opportunistic pathogens and numerous grazing protists that consume bacteria.

The burning of fossil fuels produces significant amounts of

sulfur dioxide

In a global sense, ALL nutrient cycles are coupled together.

t

Effluent water is wastewater

discharged from the wastewater treatment facility.

Geobacter sulfurreducens uses its pili to form direct connections with insoluble ferric iron particles. As the organism carries out respiration, the Fe3+ is acting as a(n) __________.

electron acceptor

Sulfate reduction (SO42- → H2S) occurs only where organic material is abundant because __________.

electrons from organic compounds are necessary for this reaction

Both ammonium (NH4+) and nitrate (NO3-) are assimilated by primary producers, but ammonium is the preferred form of nitrogen for fertilizers used in agriculture because __________.

nitrate leaches out of soils easily due to its negative charge

You have created a small-scale ecosystem in your laboratory that exactly mimics the nitrogen cycle in nature. You accidentally release a virus into your laboratory that inserts itself into (and inactivates) the gene for nitrogenase. What would you expect to happen in your ecosystem?

Atmospheric nitrogen gas would increase and soil ammonia would decrease.

The Lake of the Ozarks is a human-made lake, so it collects runoff from coal strip-mining, fertilizers, resort wastewaters, and septic drainages. The average lake temperature is between 10∘C and 21∘C. Consider the physical requirements for growth and multiplication that would allow fecal coliforms to "blossom" in the Lake of the Ozarks. Which of the following would accurately describe these organisms?

Facultative halophile, Mesophiles

Which of the following is a sulfide?

H2S, HS-, and S2- are all sulfides.

________ is a term used to describe dead organic matter.

Humus

Bacteria naturally prefer company instead of solitude for growth. Examples of this kind of communal growth pattern can be found everywhere, from surfaces of the teeth and the intestines, to the surface of a slimy rock in the lake, to the thick floc that clogs water pipes. These examples of communal bacterial growth are known by what name?

biofilm

Increases in atmospheric carbon dioxide concentrations leads to acidification of the oceans as CO2 dissolves in the water and forms carbonic acid. This acidification is predicted to have a major effect on the carbon cycle, as well as the calcium and silica cycles, due to the roles of Ca+ and Si in __________.

building the shells and frustules of microscopic algae and some animals

Human activities have disrupted the carbon cycle by

burning carbon stored as fossil fuels or biomass, thus increasing the amount of carbon dioxide in the atmosphere.

The Ca cycle is tightly coupled to the

carbon cycle through calcium carbonate formation in ocean waters.

The use of ________ to treat drinking water, which began in 1913, reduces the incidence of waterborne diseases

chlorination

To further reduce the possibility of biological contamination, MOST treatment plants treat the effluent with

chlorine.

Sulfide is toxic to respiring organisms, because it can combine with metals present in ________ that serve a critical function in respiration.

cytochromes

Which of the following processes does not involve ammonia?

denitrification

Which of the following processes does not result in a product that can be directly utilized by plants?

denitrification

Denitrification contributes to global warming by __________.

destroying ozone

The ocean has mitigated the impact of anthropogenic carbon dioxide production by

absorbing 500 billion tons of atmospheric carbon dioxide and over 80% of the trapped heat energy.

Nitrate (NO3-) reduced into ammonia (NH3) to produce energy for the cell is called

dissimilative reduction of nitrate to ammonia (DRNA).

The Fe and Mn cycles include

educed and oxidized forms that are very chemically reactive

Which statement BEST describes sewage and wastewater?

Sewage is a subset of wastewater.

In addition to physical requirements, bacterial growth and multiplication also entails chemical requirements. Which of the following statements would accurately describe chemical requirements and conditions associated with growth in the Lake of the Ozarks environment? Select all of the following statements that are true regarding fecal coliforms in the Lake of the Ozarks.

The lake environment will support the growth of facultative anaerobes. Fecal coliforms will likely contain enzymes to counteract toxic oxygen forms. Fecal coliforms will need to acquire trace elements for growth in the lake environment.

In designing a drinking water purification system for a rural African town, a Peace Corps volunteer engineer is asked by the local officials to reduce the cost of the project by eliminating one of the steps. The raw water supply from the nearby river is high in suspended solids, dissolved organic carbon, and bacterial load. Which of the answers below is NOT a reason none of the steps could safely be eliminated?

You cannot eliminate the chlorination step due to the presence of Cryptosporidium cysts in the water.

Which of the following processes does denitrification contribute to?

acid rain, ozone depletion, and global warming

Nitrogen fixation results in the

addition of biologically available N to an ecosystem

The type of wastewater treatment that would be used to reduce the BOD (biological oxygen demand) of liquid waste would be __________.

aerobic activated sludge

The two major forms of carbon that remain following microbial degradation are

methane and carbon dioxide.

Carbon dioxide and methane are potent greenhouse gases, with methane having 20 times more warming potential in the atmosphere than CO2. As global warming progresses, there is the real possibility that increased temperatures on land and in the oceans will lead to a positive feedback effect leading to accelerated warming. From the carbon reservoirs listed below with their percentage of the total carbon on Earth, what would be the most dangerous potential source of C that could be released to potentiate further warming?

methane hydrates (0.014%)

Frozen methane molecules are called

methane hydrates.

What is the main form of nitrogen found on Earth?

n2

The metabolic process of ammonification ________ ammonia.

produces

As nutrients cycle in the biosphere, __________ can participate in every transformation from one chemical form of a nutrient to another.

prokaryotes

Opportunistic pathogens such as Legionella, Pseudomonas, and Mycobacterium species have the ability to grow within ________, which may enhance their ability to survive in water distribution systems.

protists

The goal of wastewater treatment is to

reduce organic and inorganic materials in wastewater to a level that no longer supports microbial growth.

Aerobic secondary treatment is usually best for ________ wastewater.

residential

What is a characteristic of a deep sea marine cold seep/vent?

rich in methane

What is the largest carbon sink on Earth?

rocks and sediments

As a wastewater technician you are receiving sewage with a biological oxygen demand of 200. Which process would be best to treat this sewage?

secondary aerobic treatment

An engineer working for the Peace Corps is helping a small town in Africa to design a drinking water purification system. The raw water supply from the nearby river is high in suspended solids, dissolved organic carbon, and bacterial load. What would be the most effective order for the water treatment processes?

sedimentation, coagulation, filtration, disinfection

Which choice provides the steps in drinking water treatment in the correct order?

sedimentation, coagulation, filtration, disinfection, storage

More carbon is present in dead organic material on Earth than in living organisms.

t

Ocean acidification decreases the precipitation of calcium carbonate and thus will probably affect the cycling of Ca and other nutrients in the ocean

t

Secondary treatment may be aerobic or anoxic.

t

n the natural carbon cycle, carbon dioxide is returned to the atmosphere by the respiration of animals and chemoorganotrophic microorganisms.

t

One important difference between the C, N, and S cycles and the P, Ca, and Si cycles is that

the P, Ca, and Si cycles do NOT involve redox changes or gaseous forms that can alter Earth's atmospheric chemistry.

Phosphorus is cycled like carbon, nitrogen, and sulfur, except for the fact that __________.

there are no gaseous forms that can alter the chemistry in the atmosphere

A farmer wants to acidify his alkaline soils by adding elemental sulfur (S0), which will, under the right conditions, be oxidized to H2SO4 by chemolithotrophs. However, the weather report predicts heavy rains and possible localized flooding starting within in a few days and lasting for the next couple of weeks. Why should the farmer wait to apply the S0 to his fields until the soils are well-drained?

to avoid production of hydrogen sulfide (H2S) due to anoxia

The largest reservoir of methane is found

trapped under permafrost and marine sediments.

Water leaving an efficient wastewater treatment facility ideally has a biochemical oxygen demand (BOD) between ________ units

0 and 5

Which product of anoxic sewage treatment can be used to heat and power an entire water treatment facility

CH4

Decomposition of organic carbon ultimately results in the formation of __________.

CO2 in aerobic environments and CO2 plus CH4 in anoxic environments

Which of the following bacterial pathogens is found in water distribution systems?

Legionella pneumophila

Lysis of marine algae and cyanobacteria releases the major osmoregulatory solute, dimethylsulfoniopropionate (DMSP), which is degraded into the most abundant organic S compound in nature, ________.

Lysis of marine algae and cyanobacteria releases the major osmoregulatory solute, dimethylsulfoniopropionate (DMSP), which is degraded into the most abundant organic S compound in nature, ________.

There is a large plastic container of water by the soccer fields. It is labeled not potable. Should the soccer players drink this water?

No; it is not safe to drink.

Which statement exemplifies the biological pump concept?

Primary producers sink to the deep ocean, which provides deep ocean organisms with nutrients when the primary producers die.

Sampling lake water for microscopic organisms is not as easy as it sounds when you want to both count and identify species. In a given water sample, your bacteria of choice can be rare or difficult to culture, particularly given the mixture of bacteria in a biofilm. Which of the following culture media would be best for growing fecal coliforms when they are relatively less abundant than other bacteria in the lake?

enrichment culture medium

Calcium is cycled most rapidly in terrestrial environments.

f

Carbon dioxide is the only greenhouse gas produced by anthropogenic activities.

f

Energy yields are high enough for Fe2+ oxidation that the bacteria that perform this reaction require only small quantities of Fe2+ to be available.

f

In water, MOST taste- and odor-producing compounds are inorganic in nature.

f

MOST wastewater treatment facilities employ methods designed to detect each pathogenic organism that may be present in a given sample.

f

In anoxic environments, organic compounds are cycled back to carbon dioxide and methane by __________.

fermentation

Industrial production of nitrogenous fertilizers from N2 now equals or exceeds the amount of nitrogen fixation carried out by microbes in the biosphere. The resulting increase in primary production is an example of the fact that __________.

he C and N cycles are closely coupled

Cultures of the Lake of the Ozarks water samples were grown on enrichment media for identification. However, these organisms are present to some degree in all samples. An important question from a clinical perspective is whether or not there is a significant increase in the fecal coliform populations that would put people's health at risk. If you were part of the team investigating this outbreak, how would you best enumerate the fecal coliform threat

iltration count culture

With increased levels of oxidizable materials, the biochemical oxygen demand (BOD) will

increase.

Treatment of drinking water by UV irradiation is effective at ________, but it does NOT remove ________.

killing bacteria and eukaryotic pathogens / odor- and taste- altering organic compounds

Which of the following would NOT be a factor enhancing the growth and/or survival of Legionella pneumophila in drinking water distribution systems?

lack of residual chlorine in the drinking water

Bacterial oxidation of Fe2+ occurs BEST under which environmental condition?

low (acidic) pH

Many nutrient cycles are coupled and changes in one cycle will affect another. This means that a change in the amount of carbon dioxide fixed is intimately affected by the amount of __________.

nitrogen available in an ecosystem

Studying the redox cycling of Fe in the environment has led to the discovery

of bacteria that transfer electrons long distances and generate electric currents.

Diatoms require silicon due to their

ornate frustules

While wastewater is in an activated sludge tank, much of the organic matter is

oxidized, adsorbed to the floc, and incorporated into microbial cells

Which of the following is/are NOT a degradation product of organic material?

oxygen

Phosphorus reservoirs include

phosphate minerals in rocks, dissolved phosphates in aquatic environments, and the nucleic acids and phospholipids of living organisms.

Which organisms form the foundation of the carbon cycle?

phototrophs

Which treatment method(s) are used in primary wastewater treatment?

physical separation

Physical separation of solids and organic and inorganic particulates from sewage is termed _______

primary wastewater treatment