A secondary pollutant is the product of a primary pollutant already present in the atmosphere that has reacted with another substance in the open air. "Ozone" is a secondary pollutant because it is a product of hydrocarbons and nitrogen oxides (i.e. primary pollutants) that have reacted with one another in sunlight. "Carbon monoxide" from an automobile or "sulfur dioxide" from burning coal are primary pollutants, because they are released into the air by combustion, not by interacting with other molecules in the atmosphere.  

Point-source pollution is defined as pollutants that are derived from a specific source, such as a discharge pipe, ditch, canal, or smokestack. Pollutants sourced from a textile mill, paper mill, or oil refinery would fit this definition because the pollutants are originating from a specific source. Cigarette butts differ from the other possible answers because there is no specific point-source for their disposal. Millions of cigarette butts are discarded on beaches and waterways by millions of different people, and since there is no single point source for the pollution, this would be considered non-point source pollution. 

ESA (Endangered Species Act) bans the sale and transport of endangered species and protects critical habitat but does not specifically focus on water pollution or permitting. RCRA (Resource Conservation and Recovery Act) addresses the permitting of waste storage and transport, while CERCLA (Comprehensive Environmental Response Compensation and Liability Act) establishes a superfund for polluted sites and holds polluting parties accountable. Regardless, neither of those two laws directly address the issue of point-source discharging into waterways. NEPA (National Environmental Policy Act) requires federal agencies to prepare Environmental Assessments and Impact Statements for federally-funded projects, but does not address the private sector.

The Clean Water Act (CWA) allows the EPA to regulate point-source discharge of pollutants into U.S. waterways and all "navigable waters." This piece of legislation also introduced the National Pollutant Discharge Elimination System (BPDES), which is responsible for point-source discharge permits. Any company operating in the United States that commits point-source discharge is held by these regulations outlined by the Clean Water Act.

When small fish eat bacteria and phytoplankton which contain relatively high levels of mercury, they accumulate the mercury into their tissues. This describes the process of bioaccumulation.

"Acid shock" typically occurs during the spring time, when snow (which has retained and accumulated pollutants) begins to melt and runoff into lakes and rivers. Another detrimental effect of acid shock occurs during the spawning/developing stages of aquatic animals. For example, some salamanders and frogs prefer to lay eggs in "vernal pools", or temporary puddles of water only present in the spring. Acid shock can cause these pools to become too acidic; the eggs cannot properly develop, and they die off.

The algal blooms that result from agricultural runoff do not consume oxygen when they are living. The resulting die-off from overcrowding and lack of sunlight availability and decomposition process is what consumes oxygen in the ecosystem, causing fish to suffocate. 

It is also important to recognize that hypoxia is the result of insufficient oxygen in the ecosystem, while hyperoxia is when there is too much oxygen. (Consider the meanings of the prefixes "hypo-" and "hyper-".)

As of 2013, paper products made up 27 percent of the United States' municipal solid waste.

Mitigation is defined as actions taken to prevent or reduce the occurrence of natural disasters and damage to an environment. Restoration is the renewal of an environment or ecosystem after it has been almost or completely destroyed. Preservation is a collection of efforts aimed at sustaining a vulnerable or unstable ecosystem. Remediation is often the clean up or removal of contaminants from an environment. 

Mitigation is defined as actions taken to prevent or reduce the occurrence of natural disasters and damage to an environment. Restoration is the renewal of an environment or ecosystem after it has been almost or completely destroyed. Preservation is a collection of efforts aimed at sustaining a vulnerable or unstable ecosystem. Remediation is often the clean up or removal of contaminants from an environment. 

Mitigation is defined as actions taken to prevent or reduce the occurrence of natural disasters and damage to an environment. Restoration is the renewal of an environment or ecosystem after it has been almost or completely destroyed. Preservation is a collection of efforts aimed at sustaining a vulnerable or unstable ecosystem. Remediation is often the clean up or removal of contaminants from an environment.