1. Water Pollutants and their Sources

3. River and Lake Pollutants
Sewage, manure
nitrogen, phosphorus
pathogenic organisms
biodegradable chemicals – consume O2
Fertilizers
Pesticides, oil
Toxic chemicals
Sediments

4. Effects of Pollutants Oxygen depletion
septic conditions
change in biota
destruction of certain species
Biomagnification
Restrictions on fish consumption
Accumulation in sediments (benthic organisms)
more turbid waters
loss of habitats
clog fish gills
change in biota
Foaming

5. Point sources
Wastes that are collected in pipes or channels and discharged to a surface water with or without treatment
Distinguished by source
municipal sewage or wastewater
industrial waste waters
combined sewers and combined sewer overflows

6. Non-point sources Storm water runoff discharged at multiple points
Varies substantially with use of the land runoff originates from
agricultural
urban
suburban
commercial
special (e.g. golf courses)
Minimal regulation

7. Oxygen-Demanding Material
When organic substances are broken down in water, oxygen is consumed
organic C + O2 → CO2
High oxygen levels necessary for healthy stream ecology
trout require 5-8 mg/L dissolved oxygen (DO)
carp require 3 mg/L DO
aesthetic problem <1 mg/L

8. Oxygen-Demanding Material
Pollutants measured by oxygen demand potential or total organic content
biochemical oxygen demand (BOD)
chemical oxygen demand (COD)
total organic carbon (TOC)
Sources
municipal sewage -- agricultural wastes
storm water -- leachate
industrial wastes (e.g. pulp and paper, food processing, chemical processing)

9. Nutrients
Phosphorus is typically the limiting nutrient in lakes, and algae growth is linked to phosphorus inputs
Problems
aesthetics
taste and odor in drinking water
can be toxic, especially to farm animals
Disturbance in DO cycles

10. Nutrients Phosphorous Sources
fertilizers
detergents
Phosphorous can exist in a variety of chemical forms, so total P in normally measured

11. Nutrients
Nitrogen is often the limiting nutrient in ocean waters and some streams
Nitrogen can exist in numerous forms, but nitrate (NO3-), nitrite (NO2-), ammonia (NH3) are most commonly measured
Sources are primarily from fertilizers and acid deposition

12. Salts Dissolved solids, or salts, may be present as any number of ions
cations: Na+, K+, Mg2+, Ca2+
anions: Cl-, SO42-, HCO3-
Typically measures as total dissolved solids (TDS)
Water classification
freshwater <1500 mg/L TDS
brackish water 1500 – 5000 mg/L
saline water >5000 mg/L
sea water g/L

13. Salts Sources and concentration influences Effects minerals
evaporative losses
irrigation
industrial discharges
sea water intrusion
Effects
limits use for drinking
crop damage/soil poisoning

14. Suspended Solids
Organic and inorganic particles in water are termed suspended solids
May be distinguished from colloids, particles that do not settle readily
Measured by filtering a water sample, drying and weighing the filter

15. Suspended Solids Problems Sources sedimentation
may exert oxygen demand
primary transport mechanism for many metals, organics and pathogens
aesthetic
complicates drinking water treatment
Sources
storm water
wastes
erosion

16. Pathogenic Organisms
Many organisms that cause human or animal diseases colonize the intestinal tract but can live for a period of time outside the body
Carriers (who may or may not exhibit disease symptoms) excrete these intestinal tract organisms in very large numbers
When water is contaminated by excreta, the organisms can be transmitted to those who contact the water

17. Pathogenic Organisms

18. Pathogenic Organisms

19. Toxic and Hazardous Substances
Heavy metals
Other inorganic elements
Acids/bases
Oxidants/reductants
Chlorination by-products
Combustion by-products
Volatile organic compounds
Petroleum Additives
Pesticides

20. Volatile Organic Compounds
Petroleum constituents:
benzene and substituted benzenes
prevalent in gasoline, diesel fuel, heating oil
most easily transported, slow degradation, toxic

21. Volatile Organic Compounds
Oxygenated gasoline additives
added to gasoline to improve air quality
very soluble, resistant to degradation, toxic
attempt to solve one problem caused another (spills)
Methyl tertiary butyl ether (MTBE)

22. Volatile Organic Compounds
Chlorinated solvents
C1 and C2 aliphatic
widely used in degreasing, dry cleaning, extraction
somewhat soluble, volatile, difficult to degrade

23. Hydrophobic Organics/ Chlorinated Aromatics
Chlorinated Pesticides
Polychlorinated dibenzodioxins (PCDDs)
Polychlorinated biphenyls (PCBs)

24. Some Other Categories Trihalomethanes Explosives and Propellants
Phenolics
Aldehydes
Organometallics
Asbestos

25. Arsenic Occurs naturally in rock and soil
Released to groundwater under some conditions
Health effects include skin cancer, nervous system effects, and kidney disease
Major problem in Bangladesh