Major Water Pollutants

Leading Causes of Water Pollution Most water pollution comes from: Agriculture Fertilizers, pesticides, bacteria, food wastes Industrial Facilities Sewage Treatment Inorganic and organic chemicals Mining Sediment erosion, toxic chemical runoff/leaching

Agriculture Nutrient Runoff Chemical Pollution Infectious Diseases Fertilizers & Manure Pesticides Infectious Diseases Sedimentation Overgrazing

Industrial Organic & Inorganic Compounds Heavy Metals Thermal Pollution

World Wide Disposing sewage Drinking Same Water Source Bathing Washing

Wastewater Two main systems: Septic Systems Sewage Treatment Plants

Septic Systems Septic Tank Leach Field Large container holding wastewater from a household Two parts: Sludge – bottom layer of solids Septage – middle liquid layer More bacteria and nutrients Leach Field Septage distributed into soil

Sewage Treatment Plants Urban areas Sewage plants are used in urban areas bc there is not sufficient land for leach fields Primary – Screen & settling tank for large solid waste (Sludge is taken to landfill or burned) Secondary – bacteria to break down organic waste Tertiary – treatment with chemicals (chlorine, ozone) and/or UV light Last is released into streams

Testing for Water Pollutants Temperature Dissolved Oxygen BOD pH Nitrates Phosphates Turbidity Indicator species Coliform bacteria (E. coli)

Temperature Range of Tolerance Inverse relationship with Dissolved Oxygen (DO)

Dissolved Oxygen Amount of oxygen available Range 5 ppm and up Things affecting DO: Water movement  higher DO Decomposition  lower DO Temperature  Inverse relationship

Biochemical Oxygen Demand (BOD) Amount of oxygen a water system uses over a period of time at a specific temperature Low BOD = Low Pollution High BOD = High Pollution High microbial activity leads to high BOD

pH Determines solubility of nutrients Affects organism physiology Species dependent Water that has more free hydrogen ions is acidic, whereas water that has more free hydroxyl ions is basic. . For example, in addition to affecting how much and what form of phosphorus is most abundant in the water, pH also determines whether aquatic life can use it. In the case of heavy metals, the degree to which they are soluble determines their toxicity. Metals tend to be more toxic at lower pH because they are more soluble. 

Nitrate & Phosphate Limiting nutrients in aquatic ecosystems Can result in extreme algal growth Algal blooms Red tide

Turbidity A measure of the degree to which the water loses its transparency due to the presence of suspended particulates. Affects sunlight penetration Affects predator/prey interactions Affects gill function