Water Pollution Close to home…

Types of Water Pollution The contamination of bodies of water by pollutants either directly or indirectly Types of water pollution Can be anthropogenic or natural Point source or non-point source Organic or inorganic Direct or indirect Sources of freshwater pollution Agricultural Run-off, sewage, industrial discharge, solid domestic waste Sources of marine pollution Rivers, Pipelines, the atmosphere, human activities at sea, discharges (both on purpose and on accident)

Types of Water Pollution Types of aquatic pollution include… Organic Material, inorganic plant nutrients, toxic metals, synthetic compounds, suspended solids, hot water, oil, radioactive material, pathogen, light, noise, biological (invasive species) Lowers the waters ability to hold dissolved oxygen

Measuring Water Pollution Biological Oxygen Demand (BOD) Organic material can be “biodegraded” by aerobic microbes, Therefore certain types of organic pollutants increase the “BOD.” This can lead to anoxic conditions Definition: A measure of the amount of dissolved oxygen required to breakdown the organic material in a given volume of water through aerobic biological activity by microorganisms.

Measuring Water Pollution Biotic Indices Indicator Species: Plants and animals that show something about the environment by their presence, absence, abundance, or scarcity. Early warning signs that are sensitive to change Ex: Canary in a coal mine, benthic macroinvertebrates, Biotic Index: Indirectly measures pollution by assaying the impacts on species within the community according to their tolerance, diversity, and relative abundance Doesn’t measure pollutants, just their effect on biodiversity Biotic Indices are used in combination with other measures such as BOD

Eutrophication When excess nutrients are added to an aquatic ecosystem Can be natural, but we will focus on cultural or anthropogenic eutrophication The Process… 1. Fertilizer runs off into river or lake 2. High nutrient levels make algae grow faster (phosphate is often a limiting factor to growth) 3. Algal bloom forms blocking light to littoral/benthic plants which die 4. Big feeding party at surface 5. Eventually algae die too 6. Decomposed by aerobic bacteria 7. Not enough oxygen and everything dies!

Impacts of Eutrophication Water ways affected by cultural eutrophication are usually covered by green scum and/or duckweed (lemna) They also usually give off smelly gasses like hydrogen sulfide Other impacts include… Lack of oxygen Loss of biodiversity Increased turbidity of water Where do these nutrients come from???? Detergents (major phosphate source) Fertilizers (n, p, k) Livestock runoff (nitrates) Sewage Increased erosion of topsoil

Eutrophication management Strategies The Clean Water Act