Final Exam Study Guide Flashcards
What is the problem with pesticide resistance or the “Pesticide Treadmill”?
Industrial chemists are caught up in an evolutionary arms race with the pests they battle, racing to increase or retarget the toxicity of their chemicals while the armies of pests evolve ever-stronger resistance to their efforts. Because we seem to be stuck in this cyclical process, it has been nicknamed the “pesticide treadmill.” As of 2011, among arthropods (insects and their relatives) alone, there were more than 9,900 known cases of resistance to herbicides and other pesticides. Many species, including insects such as the green peach aphid, Colorado potato beetle, and diamondback moth, have evolved resistance to multiple chemicals.
What is the advantage of biofuels?
Can be grown at home and not imported. Using carbon that is already in circulation taken out of the air by plants.
What is bioaccumulation?
Fat and oil soluble toxicants accumulate in fatty tissues in a process termed bioaccumulation, which results in the animal’s tissues having a greater concentration of the substance than exists in the surrounding environment. Toxic substances that bioaccumulate in an organism’s tissues may be transferred to other organisms as predators consume prey. When one organism consumes another, the predator takes in any stored toxicants and stores them itself. Thus bioaccumulations takes place on all trophic levels. Moreover, each individual predator consumes many individuals from the trophic level beneath it, so with each step up the food chain, concentrations of toxicants become magnified.
What happened with DDT in North America?
This process, called biomagnification, occured throughout North America with DDT. Top predators, such as birds of prey, ended up with high concentrations of the pesticide because concentrations became magnified as DDT moved from water to algae to plankton to small fish to larger fish and finally to fish eating birds. Biomagnification of DDT caused populations of many North American birds of prey to decline precipitously from the 1950s to the 1970s. The peregrine falcon was almost totally wiped out in the eastern United States, and the bald eagle, the U.S. national bird was virtually eliminated from the lower 48 states. Eventually scientists determined that DDT was causing these birds eggshells to grow thinner, that eggs were breaking in the nest and killing the embryos within. In a remarkable environmental success story, populations of all these birds have rebounded since the United States banned DDT.
What are some problems with pesticides to humans?
Acutely toxic to humans and other life forms
Novel, we were never exposed to these things before
Often concentrated
Often designed to be biologically active
Pesticides are designed to kill pests
Neurotoxins - harm the nervous system
What affect do pesticides have on nutrient cycling?
Healthy functioning ecosystems provide the service of nutrient cycling. Decomposers and detritivores in the soil break down organic matter and replenish soils with nutrients for plants to utilize. When soils are exposed to pesticides or antifungal agents, the nutrient cycling rates are altered this affects the quantity of nutrients available to producers, affects their growth, and produces effects throughout the ecosystem.
How have pesticides affected honeybees?
Toxicants can alter the biological composition of ecosystems and the manner in which organisms interact with one another and their environment. In so doing, harmful compounds can threaten the ecosystem services provided by nature. For example, pesticide exposure has been implicated as a factor in the recent declines in honeybee populations. Honeybees pollinate over 100 economically important crops, and reduced pollination by wild bees has increased crops, and reduced pollination by wild bees has increased costs for farmers by forcing them to hire professional beekeepers to pollinate their crops.
Explain the reason why biomagnification occurs because of persistent chemicals.
Once a toxic substance arrives somewhere, it may degrade quickly and become harmless, or it may remain unaltered and persist for many months, years, or decades. The rate at which a given substance degrades depends on its chemistry and on factors such as temperature, moisture, and sun exposure. The Bt toxin used in biocontrol and genetically modified crops has a very short persistence time, whereas chemicals such as DDT and PCBs persist for decades. Persistent synthetic chemicals exist in our environment today because we have designed them to persist. The synthetic chemicals used in plastics, for instance, are used precisely because they resist breakdown. Sooner or later, however, most toxic substances degrade into simpler compounds called breakdown products. Often these are less harmful than the original substance, but sometimes they are just as toxic as the original chemical, or more so. For instance, DDT breaks down into DDE, a highly persistent and toxic compound in its own right.
Explain how risk assessment works.
Risk is expressed through probability - The quantitative measurement of risk and the comparison of risks involved in different activities or substances together are termed risk assessment. Risk assessment is a way to identify and outline problems. In environmental health, it helps ascertain which substances and activities pose health threats to people or wildlife and which are largely safe.
Describe effective risk management with respect to toxics.
Risk management, e.g., with respect to toxics - Accurate risk assessment is a vital step toward effective risk toward effective risk management, which consists of decisions and strategies to minimize risk. In most nations, risk management is handled largely by federal agencies. In the United States, these agencies include the Environmental Protection Agency (EPA), the Centers for Disease Control and Prevention (CDC), and the Food and Drug Administration (FDA). In risk management, scientific assessments of risk are considered in light of economic, social, and political needs and values. Risk managers assess costs and benefits of addressing risk in various ways, with regard to both scientific and non-scientific concerns, before making decisions on whether and how to reduce or eliminate risk.
Two approaches to protections from toxics:
Innocent until proven guilty (U.S. approach) Doesn’t slow technology but allows mistakes.
Precautionary Principle (guilty until proven innocent; European Approach) Slows technology, but prevents mistakes.
Innocent until proven guilty (U.S. approach) Doesn’t slow technology but allows mistakes.
Innocent until proven guilty (U.S. approach)
Doesn’t slow technology but allows mistakes. One approach is to assume that substances are harmless until shown to be harmful. We might nickname this the “innocent until proven guilty” approach. Because thoroughly testing every existing substance (and combination of substances) for its effects is a hopelessly long, complicated, and expensive pursuit, the innocent until proven guilty approach has the virtue of facilitating technological innovation and economic activity. However, it has the disadvantage of putting into wide use some substances that may later turn out to be dangerous.
What is the US Toxic Substances Control Act?
In U.S.: Toxic Substances Control Act - directs the EPA to monitor the roughly 83,000 industrial chemicals manufactured in or imported into the United States, ranging from PCBs to lead to bisphenol A. The act gives the agency power to regulate these substances and ban them if they are found to pose excessive risk.
What E-waste management concepts are taking hold in Europe?
Concepts taking hold in Europe:
Life cycle engineering - Producer responsibility for entire life cycle of products
Extended Producer Responsibility - producer responsible for making and accepting at end of useful life
Materials that biomagnify
Heavy metals (lead, mercury)
Radioactive isotopes
Some pesticides (e.g., DDT)
Others: e.g., PCB
Asymmetries of costs and benefits of toxics and toxics regulation - Nature of costs and benefits
Nature of costs and bens - In environmental health and toxicology, comparing costs and benefits can be difficult because the benefits are often economic, whereas the costs often pertain to health. Moreover, economic benefits are generally known, easily quantified, and of a discrete and stable amount, whereas health risks are hard to measure probabilities, often involving a small percentage of people likely to suffer greatly and a large majority likely to experience little effect. When a government agency bans a pesticide, it may mean considerable economic loss for the farmer, whereas the benefits accrue less predictably over the long term through healthier people, lower healthcare costs, and increased worker productivity. Because of the lack of equivalence in the way costs and benefits are measured, risk management frequently tends to stir up debate.
List three types of pesticides
To suppress pests and weeds, people have developed thousands of chemicals to kill insects (insecticides), plants (herbicides), and fungi (fungicides). Such poisons are collectively termed pesticides. The highly modified ecosystems of industrial farming limit the ability of natural mechanisms to control pest populations. Hence, as industrial agriculture grew in use, farmers turned to chemical means to control agricultural pests.
What is biomagnification?
The magnification of the concentration of toxicants in an organism caused by its consumption of other organisms in which toxicants have bioaccumulated.
What is a Carbon Cycle?
A major nutrient cycle consisting of the routes that carbon atoms take through the nested networks of environmental systems.
Carbon cycles globally (through atmosphere and living things)
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth. Along with the nitrogen cycle and the water cycle, the carbon cycle comprises a sequence of events that are key to making the Earth capable of sustaining life; it describes the movement of carbon as it is recycled and reused throughout the biosphere.The global carbon budget is the balance of the exchanges (incomes and losses) of carbon between the carbon reservoirs or between one specific loop (e.g., atmosphere ↔ biosphere) of the carbon cycle. An examination of the carbon budget of a pool or reservoir can provide information about whether the pool or reservoir is functioning as a source or sink for carbon dioxide.
Details of the Kyoto Protocol
2005 Kyoto Protocol - Mandated signatory nations, by the period 2008-2012, to reduce emissions of six greenhouse gases to levels below those of 1990. The US was the only developed nation that didn’t ratify, and it’s refusal to join the global effort generated widespread resentment and undermined the treaty’s effectiveness (since the US generates ⅕ of greenhouse gases). The protocol itself has not had an effect on greenhouse gases.
Describe mitigation versus adaptation
Mitigation - reduce the problem, lower CO2 emissions. Why aren’t we doing this? Because it admits blame and means a large change in behaviors.
Adaptation - reducing the negative effects of GCC. Accepting it is going to happen and asking how we can adapt. Why are we doing this? Because it is easier to build a sea wall instead of changing our lifestyles.
Movement between atmosphere and biota: photosynthesis and respiration
Carbon dioxide leaves the atmosphere through photosynthesis, thus entering the terrestrial and oceanic biospheres. Carbon dioxide also dissolves directly from the atmosphere into bodies of water (oceans, lakes, etc.), as well as dissolving in precipitation as raindrops fall through the atmosphere. When dissolved in water, carbon dioxide reacts with water molecules and forms carbonic acid, which contributes to ocean acidity. It can then be absorbed by rocks through weathering. It also can acidify other surfaces it touches or be washed into the ocean.
Describe the carbon reservoirs and the movement between them.
The global carbon cycle is now usually divided into the following major reservoirs of carbon interconnected by pathways of exchange:
- The atmosphere
- The terrestrial biosphere
- The oceans, including dissolved inorganic carbon and living and non-living marine biota
- The sediments, including fossil fuels, fresh water systems and non-living organic material, such as soil carbon
- The Earth’s interior, carbon from the Earth’s mantle and crust. These carbon stores interact with the other components through geological processes
The carbon exchanges between reservoirs occur as the result of various chemical, physical, geological, and biological processes. The ocean contains the largest active pool of carbon near the surface of the Earth. The natural flows of carbon between the atmosphere, ocean, and sediments is fairly balanced, so that carbon levels would be roughly stable without human influence.
What is the record of Kyoto Protocol?
The US was the only developed nation not to ratify the Kyoto Protocol. Because the US emits ⅕ of greenhouse gases, its refusal to join this global effort generated widespread resentment and undermined the treaty’s effectiveness. US leaders called the treaty unfair because it required industrialized nations to reduce emissions but did not require the same of rapidly industrializing nations such as China and India. Proponents of the Kyoto Protocol countered that the differential requirements were justified because industrialized nations created the current problem and thus should take the lead in resolving it. In recent years, representatives of the world’s nations have met at a series of conferences, trying to design a treaty to take effect once the Kyoto Protocol ends in 2012. These climate negotiators could not reach a consensus at their 2009 meeting in Denmark. Here, the world’s two biggest greenhouse gas emitters, China and the US, did not offer enough to satisfy other nations. China promised steep emissions cuts but proved unwilling to allow international monitoring to confirm them. Obama chose not to promise more than the US Congress agreed to. In 2010, developed nations promised to pay under-developed nations up to $100 billion per year for mitigation and adaptation.
Pros and cons of nuclear relative to fossil fuels
Using fission nuclear power plants generate electricity without creating the air pollution from stack emissions that fossil fuels do. Nuclear power helps us avoid emitting 600 million metric tons of carbon each year or 7% of global emissions. Nuclear power produces waste that is radioactive and safe disposal is challenging. If an accident happens at a plant, or a plant is sabotaged, the consequences can potentially be catastrophic.
Renewable energy sources
Renewable energy sources include biomass, hydropower, solar, wind, geothermal, and ocean energy sources. Biomass and hydropower are well established and widely used sources. the other renewable sources are often termed “new renewables” because they are not yet widely used sources.
US EPA regulation of CO2 as an air pollutant
On September 20, 2013, the U.S. Environmental Protection Agency announced its first steps under President Obama’s Climate Action Plan to reduce carbon pollution from power plants. EPA is proposing carbon pollution standards for new power plants built in the future, and is kicking off the process of engagement with states, stakeholders, and the public to establish carbon pollution standards for existing power plants.
