Selenium is a chemical that affects the water stream. There are many chemicals that affect the Earth and it's organisms.a. Visit the Environment Protection Agency's website (epa.gov) and find "Chemicals and Toxics" under Environmental Topics to answer the following questions.

i.Choose at least three chemicals at random. Read about each chemical and explain where it is found and how it affects organisms, air, etc.

ii.Create one master list of all the chemicals you researched and categorize them as either human caused or caused by natural events. Which list is longer, human-caused or nature-caused?

iii.Does human impact play a role in the creation of these chemicals? What actions could hu-mans take to decrease the development of these chemicals? What actions might you specifi-cally take to decrease the development of these chemicals?

b. Go to the website www.pubmed.gov and find the article: Mercury and Selenium in Fish of Fountain Creek, Colorado (USA): Possible Sources and Implications. Download the pdf file of the article to your computer. This article is free. If you are asked to pay money for the article then you have done some-thing wrong and should start over.

i.What is causing the high selenium content in Fountain Creek, Colorado? Name two of the fish collected in order to conduct the scientists' research (you may use their common names or their scientific names).

ii. Name one of the fish that was found with the highest selenium content found? Did the sele-nium (Se) content increase or decrease as the water flowed downstream? What about the mercury (Hg) content?iii.Based on this article that you found on www.pubmed.gov, describe what you learned from two of the figures and/or tables. 

EPA topic

a. Chemicals, Source, and Effects

a.1. Mercury

Sources: batteries, compact fluorescent light bulbs, dental amalgams, thermometers, thimerosal in vaccines, and other consumer products such as antiques, appliances, automotive parts, barometers, electronics, jewelries, skin creams, and sporting equipment

Effects: Mercury both from natural sources such as volcanic eruptions and forest fires, and human-related sources, can result to the release of mercury to the atmosphere, to different bodies of water, and to the land. Airborne mercury can then fall to the ground in raindrops, in dust, or simply due to gravity, increasing the levels of mercury on land and water even more. It is consequently possible for animals, plants, and us humans to acquire various mercury products from the contamination of these abiotic sources. The bioaccumulation of mercury in living organisms can produce both direct toxic effects to the organism exposed to the element and indirect effects to the organisms at successive trophic levels consuming the contaminated organism. A very important factor in the impacts of mercury to the environment is its ability to build up in organisms and up along the food chain. Mercury has been shown to cause deformities in a developing organism and can cause damage on the organ systems of different animals, specifically the liver and the kidneys. Accumulation of mercury in plants causes abnormal germination, reducing biomass production, inhibiting photosynthesis, and impairing water absorption.

a.2. Lead

Sources: Lead is found basically everywhere. Human activities including the use of fossil fuels, leaded gasoline, some types of industrial facilities, and the use of products such as paint, ceramics, pipes and plumbing materials, solders, gasoline, batteries, ammunition, and cosmetics, comprise the majority of the source for human exposure. Lead can then enter the environment from these vehicles. Lead can also be emitted into the environment from industrial sources and contaminated sites, such as former lead smelters. Lead is also occasionally found on drinking waters, consumer products, and even food. The most common sources of lead in drinking water are lead pipes, faucets, and fixtures.

Effects: Similarly as mercury, lead can also accumulate in air, water and in land. Lead can remain in the environment as dust indefinitely. The lead in fuels contribute to air pollution, especially in urban areas. Soils near highways, freeways, and smelting facilities are at high risk for lead contamination. The presence of lead can accumulate throughout time, therefore increasing the toxicity on the exposed organisms. Plants exposed to lead can absorb the metal dust through their leaves and minimally through uptake from the soil. Lead effects on plants include its negative effects on photosynthesis, retardation of growth, blackening of roots, and others. Lead is toxic to many organs and tissues including the heart, bones, intestines, kidneys, and reproductive and nervous systems.

a.3. Formaldehyde

Sources: Formaldehyde can be found in resins used in the manufacture of composite wood products, building materials and insulation, household products such as glues, permanent press fabrics, paints and coatings, lacquers and finishes, and paper products, preservatives used in some medicines, cosmetics and other consumer products such as dishwashing liquids and fabric softeners, and fertilizers and pesticides. It is also a byproduct of combustion and is also found in emissions from unvented, fuel burning appliances, like gas stoves or kerosene space heaters and cigarette smoke.

Effects: Majority of formaldehyde effects focus on humans and animals. Eye and upper respiratory tract irritation, headaches, and gastrointestinal problems are the predominant symptoms associated with exposure to formaldehyde. Skin irritation and allergic dermatitis have also resulted from exposure, and experiments have shown that individuals can become sensitized.

b. Human-caused vs Nature-caused Chemicals

Possible nature-caused

Fluorine - natural geologic sources

Mercury - mining and natural resources

Selenium - natural geologic resources, sulfur and coal

Human-caused

Arsenic - mining by-product, pesticides, chemical waste

Cadmium - industrial discharge, mining waste, metal plating

Beryllium - nuclear power and space industries

Boron - Detergent formulations, industrial wastes

Chromium - metal plating, cooling water additive

Copper - industrial and domestic waste, mineral leaching

Lead - mining, plumbing, gasoline

More chemicals are human-caused as compared to nature-caused.

c. There is no doubt that behind this continuous expansion of human knowledge together with the gobal industrialization has dealt a massive destruction to our very own environment. The advancements of mining, farming, forestry and agriculture may all be because of the search of a better standard of living, but humans are now slowly paying the price.

As humans, there is still a great need to improve the ability to predict the environmental consequences of everything. for example of a new chemical before the great expenditure of getting it into the marketplace is undertaken. Much better proficiency in addressing such environmental questions is crucial and should greatly improve the ability to develop regulations appropriate to the problem. In addressing the modern industry, it needs to have greater assurance that its often expensive product development and commercialization will be successful and not quickly overturned by unforeseen human health or environmental problems. As consumers and members of this growing society, let us practice recycling, reducing, and reusing, this may be small, but together, it can be a big relief to mother earth.

Mercury and Selenium in Fish of Fountain Creek, Colorado

a. The high selenium content in Fountain Creek is attributed from its drainage from El Paso County which is the most populous county in Colorado with over 560,000 residents. Cumulative effect of selenium-involving human activities in El Paso County caused the high selenium contamination of Fountain Creek. The researchers used Longnose (C. catostomus) and white suckers (C. commersonii) as part of their specimen.

b.  The highest whole-body selenium was measured in northern creek chubs and white suckers in Pueblo, Colorado at site LF-4 while the highest mercury was in white suckers, flathead chubs and stonerollers from the Monument Creek tributary north. From site LF-1 downstream, Se in the fish showed a marked increase in the metalloid as the water flowed downstream, especially at the LF-4 and LF-5 sites located in the City of Pueblo, Colorado.  Mercury, on the other hand, was higher in fish collected from the upper segments of Fountain Creek and Monument Creeks.

c. Figures from the study show that Flathead Chub accumulates the greatest selenium concentration, making it possibly useful as a bio-monitoring species for selenium in different bodies of water. Creek Chub, on the other hand, accumulates the greatest mercury concentration among all fish species, raising its potential for its use in mercury bio-monitoring in the future. Ovaries of Flathead Chub and the muscles of Creek Chub can specifically be investigated for bio-monitoring because of its high accumulation for selenium and mercury, respectively.