1. Water Resources and Pollution

2. Summary Available freshwater is in limited supply Groundwater is being withdrawn from aquifers faster than it can be recharged Dams provide freshwater reservoirs and hydroelectric power but disrupt ecosystems, displace people and valuable arable land Human activities (like agricultural runoff, industrial discharge, mining practices) pollute aquatic ecosystems and groundwater Sewage treatment plants help reduce water pollution

3. Strategies to Protect Groundwater Increase price of water to discourage waste Reduce use of crops that need excessive watering Reduce use of fertilizers, pesticides and industrial chemicals Implement water conservation practices in homes Gov’t susidies or tax breaks for water conservation

4. Improving Irrigation Methods 40% of the freshwater used in U.S. goes to irrigation of crops using flood irrigation Drip irrigation or micro-irrigation is more efficient (95%) because water is delivered slowly directly to roots = no evaporation or runoff – ALSO INCREASES CROP YIELDS BY 20-90%!!!!!! Center pivot – increases water use efficiency to 80%

5. Industrial and Residential Water Conservation Introduce grey water systems where water that is not contaminated by residential sewage or industrial chemicals is diverted and collected for use on lawns, washing cars, flushing toilets Use low-flow showerheads and low-volume toilets Recycle industrial-use water within the factory

6. Water Testing Techniques Physical water Quality Temperature – affects DO (dissolved oxygen) levels and reproductive cycles River/Stream Flow Velocity Turbidity – measures cloudiness of water due to suspended solids. Water clarity is important to photosynthesis in aquatic systems!

7. Water Testing Techniques Chemical Water Quality pH – most organisms require pH of 6-9 DO – dissolved oxygen must be at least 5ppm or organisms become stressed = unhealthy ecosystem – Highest in cold, fast-moving water – If DO is low, may indicate cultural eutrophication (excess fertilizer), sewage or thermal pollution (artificially warm water from electrical power plants) Nitrates/Nitrites & Phosphates lead to eutrophication usually from fertilizer runoff, sewage, septic tank leaks, animal waste from factory farming Hardness – presence of metals in water which may increase due to acid rain (causing increased solubility & loss of ability to buffer the pH of aquatic systems)

8. Water Testing Techniques Biological Water Quality Fecal Coliform – indicates fecal contamination from sewage, septic tank leaks, animals waste from factory farming Biological Indicators – monitoring of organisms to measure ecosystem health over time – Benthic macroinvertebrates: aquatic insects and their larvae, crustaceans. E.g., stonefly, mayfly, caddisfly. – Fish species: sensitive to DO concentrations, temp & pH

9. Groundwater Pollution Nondegradable wastes (arsenic, lead, fluoride) can remain permanently Slowly degradable wastes (DDT and other pesticides, herbicides, fungicides) can persist for tens – thousands of years Prevention & Remediation (cleanup) – Prevention more cost effective! – Remediation methods include injecting microorganisms into aquifers to degrade pollutants or water pumped to surface to be cleaned and returned to aquifer – ALL VERY EXPENSIVE!

10. Preventing Groundwater Pollution Protect natural water filtration systems (wetlands and river buffer zones) Use alternative energy sources to reduce mercury emissions from coal-burning power plants Sustainable Agriculture not factory farming – Reduce soil erosion by keeping land covered with vegetation (called no-till agriculture) – Reduce fertilizer use to bare minimum or farm organically – Use integrated pest management (IPM) not pesticides – Limit or eliminate large animal feedlots/factory farms

12. Sewage Treatment Primary – physical process using screens and grit tank to remove large debris – Solids settle out as sludge Secondary – biological process where aerobic bacteria breakdown wastes in aeration tanks – Additional solids settle out as sludge – Water then treated with chlorine (can react becoming chlorinated hydrocarbons linked to human endocrine and nervous system damage – Safer alternatives to chlorination are ozone or ultraviolet light Advanced or tertiary treatment – used to remove excess nitrates from fertilizer-contaminated water

13. Diagram showing Primary, Secondary & Tertiary Treatment

14. Secondary Treatment – Aeration Tank with aerobic bacteria hard at work “activated sludge”

15. Additional Sewage Treatment Options – use natural ecosystem services as a model! Sludge from sewage treatment facilities can be incinerated or treated for harmful bacteria, toxic metals and then can be applied as fertilizer Require industries to remove toxic and hazardous waste before reaching municiapl sewage treatment plant (E’town requires this) Use natural and artificial wetland systems to treat sewage: water pumped into oxidation ponds where bacteria break down organic waste for 30 days, then pumped into marsh where plants and bacteria filter and clean water

16. Water Quality Legislation