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Water Chemistry and Pollution

Water Chemistry and Pollution

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Water Chemistry and Pollution

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  1. Water Chemistry and Pollution

  2. Why we measure water quality? • When a body of water is overfed with nutrients it can create massive algal blooms which causes very low levels of DO killing off many aquatic organisms. •

  3. Pfiesteria Found in waters high in nutrients -Harmful Algal Bloom (HABs)

  4. A fertilized lake designated "Lake 227" in northwest Ontario, Canada, (foreground) with increased algae, whose growth has been found unpredictable, pictured next to a lake that hasn't been manipulated for research. (Photo by Karen J. Scott

  5. Would you want to swim at this beach? • “Under the belief that water could dilute any substance, industries and individuals during the 18th and 19th centuries often used rivers and lakes as garbage cans. Industrial effluent, raw sewage and animal carcasses would often be dumped into waterways, without much thought of contamination and downstream neighbors.”

  6. Eutrophication • Excessive Nutrients: N>3ppm P>.01ppm • Causes excessive growth of marine autotrophs (large algal blooms) • Die off of Marine Plants = Lack of Light • Decomposition of marine plants uses more oxygen which can lead to an “oxygen sag” in an aquatic environment

  7. The Dead Zone • Oxygen minimum zone that develops annually in response to nutrient and other inputs to the Gulf of Mexico. • Hypoxic - <2.0mg/l of dissolved oxygen • Anoxic – 0.0mg/l of dissolved oxygen

  8. To determine the health of a body of water, many parameters or guidelines are monitored including Coliform Bacteria, Dissolved Oxygen (DO), Nitrate/Nitrite, Phosphate, pH, Temperature, & Turbidity

  9. Coliform Bacteria • EPA standards: One coliform colony / I00 mL of water is cause for concern • Four colonies per 100 mL requires direct action • The appearance of coliform bacteria indicates the presence of raw sewage. Raw sewage may contain disease-producing bacteria. • Coliform is an indicator species. • A coliform test measures the amount of E. coli present in the water supply

  10. DO is dependent on a number of factors including salinity, temperature, photosynthesis rates atmospheric pressure, and the amount of wind & wave turbulence. The suitability of a body of water for organisms to live can be determined by the amount of DO in the water. Fish require 4-5 mg O2/liter of water while air breathing aquatic organisms require less. Dissolved Oxygen

  11. EPA standards: Nitrate cannot exceed 10 mg/L Excess levels of nitrates can cause hypoxia. Excess nitrite can cause the “blue baby syndrome” and is toxic to warm-blooded organisms. Natural levels of nitrates in surface water is <1mg/L. Essential nutrient for plants & animals. Sources of nitrates come from the atmosphere (automobile exhaust), fertilizer runoff from land, animal excrement, sewage wastes, and plant debris. Wastewater treatment plants can have nitrate levels as high as 30mg/L. Nitrates/Nitrites

  12. Phosphates • Phosphorus is also an essential nutrient for the plants and animals that make up the aquatic food web. • Phosphorus is naturally available in low concentrations and is often limited. • Small increases can result in accelerated plant growth, algae blooms, low dissolved oxygen, and the death of certain fish, and other aquatic animals. • Sources of phosphorus include soil and rocks, wastewater treatment, fertilizer runoff, failing septic systems, runoff from animal manure, disturbed land areas, drained wetlands, and commercial cleaning preparations.

  13. pH • pH describes how acidic or alkaline a substance is. Acidity increases as the pH gets lower (pH of 7 being neutral). • pH affects many chemical and biological processes in the water. • Most aquatic organisms prefer a range of 6.5-8.0. Water higher or lower than the range decreases biodiversity, & reduce reproduction. • Low pH can also allow toxic elements to become mobile & “available” for uptake by aquatic plants. This can be particularly dangerous to sensitive species like rainbow trout. • Changes in pH occur from acid rain, wastewater treatment plants, and leaching from surrounding rock beds.

  14. Turbidity • Turbidity measures the amount of particles suspended in a body of water such as soil particles (clay, silt, sand), algae, plankton, microbes, and etc. • Higher turbidity increases water temperatures because the particles absorb more heat reducing the amount of DO. Warm water holds less DO than cold. Higher turbidity reduces the amount of light penetrating the water, and reduces photosynthesis. Suspended materials can clog fish gills, decrease resistance to disease & affect egg/larval development • Sources include soil erosion & runoff, waste discharge, eroding stream banks, bottom feeders (carp). Turbidity has no direct human health effects but can provide a medium for microbial growth.

  15. Indicators vs. actual chemicals • Ecotoxicology- pollutants in the ocean • Eating too much of certain seafood is harmful • We looked at the chemistry of the water. Now we will look at the chemistry of the animals in the water

  16. Why are we concerned about ocean pollution? • Transportation • Coastal ocean is used most heavily-76% of fisheries!! • recreation- jet skis, cruise ships

  17. Causes • Natural (not all are human-caused) • Volcanoes- atmospheric pollutants (ash, SO2) • Underwater seeps • Anthropogenic • Anthro=humans • Industry, mining, agriculture, transportation • Recreation

  18. 4 main pollutants • Petroleum-least damaging, can be broken down naturally • Sewage sludge-water treatment does not treat for chemicals, only treats waste • Toxic chemicals • DDT (banned), PCB’s, PAH’s • Still in environment today • Heavy metals • Lead, mercury, methylmercury

  19. What is mercury? • Heavy, silvery-white liquid • Only metal that is liquid at ambient temp. • Mad as a hatter • Naturally in environment from volcanic eruptions and weathering of rocks- but miniscule compared to human-caused • Environmental neurotoxin affects growth, reproductive success, and development in plants and animals

  20. Uses of mercury • Electrical products-switches, wiring, thermostats, batteries, etc. • Dentistry • Medical products-antiseptics, laxatives • Thermometers • Pharmaceutical preservatives- thimerosal • Industrial processes- byproduct of coal-burning power plants, fossil fuel combustion

  21. Effects of Mercury • Neurological complications on a developing fetus • Sensory disturbances (blindness) • Lack of coordination (slurred speech) • Reproductive failure • Impaired growth • Loss of motor skills • Loss of IQ points • Cardiovascular problems

  22. Different forms of mercury • Elemental mercury-does not affect humans • Inorganic mercury-does not affect humans, gets transformed by bacteria into methylmercury • Methylmercury-also called organic mercury, poisonous, absorbed into tissue

  23. Bioaccumulation: build-up in concentration of something with each step of the food chain • Crosses the blood/brain barrier and placenta • Eliminated from living tissue very slowly • Is contained in fish flesh and is not reduced or removed by cleaning, trimming or cooking • Bioconcentration: comparison between creature’s concentration and concentration in environment (i.e. seawater)