Management of Non-Point Source Pollution CE 296B

1. Management of Non-Point Source PollutionCE 296B Department of Civil Engineering California State University, Sacramento Lecture #8, February 26, 1998 Sources of Pollutants - Part IV

2. Recall that we were looking at the six categories of pollutants: 1. Toxic inorganics - e.g. metals 2. Synthetic organics - e.g. solvents 3. Biostimulants - BOD, nutrients Left off here 4. Sediment - clay, silt, sand, gravel 5. Pathogenic organisms - viruses, bacteria, protozoa 6. Trash - use your imagination

3. And the framework for acquiring knowledge about each category: • 1. What are the sub-categories in each category and what are representative members? • 2. What are the origins of pollutants? • 3. How pollutants are introduced to the flow stream? • 4. How pollutants behave in water? and here

4. IV. The third category of pollutant to examine is biostimulants. (cont.) E. Examine the concept of a rate limiting nutrient: 1. On a dry weight basis, the primary members of the food chain have a relatively similar make-up in terms of proportions of elements.

5. Typical Elemental Proportions in Microorganisms

6. IV. The third category of pollutant to examine is biostimulants. (cont.) • E. Examine the concept of a rate limiting nutrient: (cont.) 2. Primary members of the food chain require elements roughly in the proportions listed. Excluding the oxygen and hydrogen associated with cell water, we are left with: • Carbon - 50 % of total • Nitrogen - 14 % of total • Phosphorous - 8 % of total

7. Thus, the amount of nitrogen added controls the level of biological activity. P N C Balanced amount of each nutrient Amount of each nutrient available, nitrogen controls here Amount of each nutrient actually used Representation of Limiting Nutrient Concept Balanced amount of each nutrient Amount of each nutrient available, nitrogen controls here Amount of each nutrient actually used

8. IV. The third category of pollutant to examine is biostimulants. (cont.) • E. Examine the concept of a rate limiting nutrient: (cont.) 3. Thus, for each water body, there will be a limiting nutrient. Because of the ability of algae to fix CO2 via oxygenic photosynthesis, the rate limiting nutrient is usually nitrogen or phosphorous. If nitrogen is not the rate limiting nutrient, it will eventually be denitrified to molecular nitrogen. If phosphorous is not the rate limiting nutrient, it may accumulate in the system.

9. IV. The third category of pollutant to examine is biostimulants. (cont.) • E. Examine the concept of a rate limiting nutrient: (cont.) 4. As it is difficult to assess if a water body is nitrogen or phosphorous limiting, it has been considered good practice to limit the introduction of both in excess. 5. It is also difficult to assess just how much nitrogen or phosphorous is required for the water body to be healthy.

10. Discussion Break Imagine that, through an extremely aggressive program, both nitrogen and phosphorous inputs to Santa Monica Bay were lowered to an extremely low level, below the “natural” input. What might happen to the Kelp Harvesting Industry there? Something like this has happened to the south bay from the San Jose Wastewater Treatment Plant.

11. Discussion Break What kind of environmental trade-offs might exist in a substantial campaign to plant trees in a city?

12. IV. The third category of pollutant to examine is biostimulants. (cont.) F. How do biostimulants behave in water? 1. Carbon: a. Aerobic oxidation of organic compounds consumes dissolved oxygen. Desirable fish species (trout, bass, etc.) are more sensitive to reduction in D.O. concentration than rough fish (e.g., carp). D.O. concentrations are most often a central Water Quality Objective.

13. Discussion Break If one where to establish priorities for Water Quality Objectives, where would dissolved oxygen rank? Why? Which reasons are scientific and which are emotional?

14. IV. The third category of pollutant to examine is biostimulants. (cont.) • F. How do biostimulants behave in water? • 1. Carbon: (cont.) b. It is usually considered a minor consideration, but as organic material is oxidized and CO2 is produced, the alkalinity of the water increases. c. Organic compounds that are less degradable remain in system for an extended period of time. They may: • Decay anaerobically in bottom sediments releasing NH3, PO4-3, and producing H2S • Complex with other constituents, e.g. metals

15. IV. The third category of pollutant to examine is biostimulants. (cont.) • F. How do biostimulants behave in water? • 1. Carbon: (cont.) d. Become part of beneficial natural processes. 2. Nitrogen: a. Undergo transformations associated with nitrogen cycle. Note that as with carbon, there is an escape route for nitrogen. It may be transformed by denitrification to N2. b. Nitrification process consumes D.O. and produces strong acid.

16. IV. The third category of pollutant to examine is biostimulants. (cont.) • F. How do biostimulants behave in water? (cont.) • 2. Nitrogen: (cont.) c. Free ammonia (NH3) can be toxic to fish. The Tulare Basin Plan has a water quality objective of 0.025 mg/L as N. The concentration of free ammonia is a function of three things: • Total ammonia concentration (NH3 plus NH4+) • pH • Temperature Equilibrium Relationship

17. Discussion Break Ammonia is toxic to fish everywhere. Some Basin Plans specifically list ammonia concentrations in the Water Quality Objectives. The Los Angeles Region and Tulare Basin are two examples. Other Basin Plans simply give an acceptable pH range. The Colorado Basin and Central Valley Basin are two examples. Which approach to you prefer? Why?

18. IV. The third category of pollutant to examine is biostimulants. (cont.) • F. How do biostimulants behave in water? (cont.) • 2. Nitrogen: (cont.) d. In the capacity of a rate limiting nutrient, excess nitrogen would stimulate excess growth of primary members of the food chain, particularly algae. This would in turn lead to a depletion of D.O. and the subsequent negative effects associated with depressed D.O. levels.

19. IV. The third category of pollutant to examine is biostimulants. (cont.) • F. How do biostimulants behave in water? (cont.) 2. Phosphorous: a. Major difference between phosphorous and the other two major biostimulants, carbon and nitrogen, is that the phosphorous cycle does not have a gas phase component. Thus, in the absence of a flushing mechanism, phosphorous inputs to a water body will continue to accumulate.

20. IV. The third category of pollutant to examine is biostimulants. (cont.) • F. How do biostimulants behave in water? (cont.) • 2. Phosphorous: (cont.) b. As with nitrogen, if phosphorous is the rate limiting nutrient, excess phosphorous would stimulate excess growth of primary members of the food chain, particularly algae. This would in turn lead to a depletion of D.O. and the subsequent negative effects associated with depressed D.O. levels.

21. Discussion Break Every water body requires some input of biostimulants to remain healthy. How might we “draw the line” between required biostimulants and excess biostimulants? What would the implications of incorporating this idea into the Clean Water Act?

22. Recall that we were looking at the six categories of pollutants: 1. Toxic inorganics - e.g. metals 2. Synthetic organics - e.g. solvents 3. Biostimulants - BOD, nutrients 4. Sediment - clay, silt, sand, gravel  On to here 5. Pathogenic organisms - viruses, bacteria, protozoa 6. Trash - use your imagination

23. And the framework for acquiring knowledge about each category: • 1. What are the sub-categories in each category and what are representative members? • 2. What are the origins of pollutants? • 3. How pollutants are introduced to the flow stream? • 4. How pollutants behave in water?

24. V. The fourth category of pollutant to examine is sediment. A. Define what a sediments are: Sediments are the dirt under our feet. 1. Components are:

25. V. The fourth category of pollutant to examine is sediment. • A. Define what a sediments are: (cont.) 2. Important considerations associated with gravel: • Requires a substantial current to transport, only during flood events • Could conceivably contribute to clogging of shipping channels or damage of habitat, but generally, this is not something associated with gravel. • Is a crucial ingredient for spawning beds

26. Discussion Break What about gravel mining (aggregate operations) along stream beds? Pollution effects? Non-point or point source pollution?

27. V. The fourth category of pollutant to examine is sediment. • A. Define what a sediments are: (cont.) 3. Important considerations associated with sand: • Current required to transport is still substantial. • Contributes to clogging type problems, both for navigation and habitat degradation. • Active ingredient for beaches • Helpful in spawning grounds • Low surface to volume ratio, little adsorption takes place.

28. V. The fourth category of pollutant to examine is sediment. • A. Define what a sediments are: (cont.) 4. Important considerations associated with silt: • Easy to transport, slow current will do. • May have substantial contributions to clogging type problems, both for navigation and habitat degradation. • Moderate surface to volume ratio, some adsorption takes place. • Will have a substantial effect on turbidity

29. V. The fourth category of pollutant to examine is sediment. • A. Define what a sediments are: (cont.) 5. Important considerations associated with clay: • Very easy to transport, slow current will do. Small enough to behave as a colloidal particle, settles very slowly in a water column. • May have substantial contributions to clogging type problems, both for navigation and habitat degradation. • Moderate surface to volume ratio, some adsorption takes place.

30. V. The fourth category of pollutant to examine is sediment. • A. Define what a sediments are: (cont.) • 5. Important considerations associated with clay: (cont.) • High surface to volume ratio, substantial adsorption takes place. Associated with clay particles may be high concentrations of: • Organic acids (humic and fulvic) • Metals • Synthetic organics • Will have a substantial effect on turbidity

31. Top Soil Sand and Gravel Bedrock V. The fourth category of pollutant to examine is sediment. (cont.) B. Sources of sediments: Seems obvious and it is. Two groups: 1. Soil as nature delivered it. Soil horizon: 2. Dirt that has been relocated by humans. All mixed up.

32. Discussion Break With respect to soil components, what difference would it make if erosion took place in a soil environment vs. a fill environment?

33. V. The fourth category of pollutant to examine is sediment. (cont.) C. How are sediments introduced to the flow stream? 1. Atmospheric scrubbing during rainstorms. Wetfall. There can be notable concentrations of suspended solids in a rainstorm. 2. Erosion I. Sheet flow over exposed soil, no plant cover or pavement, mobilizes soil particles.

34. V. The fourth category of pollutant to examine is sediment. (cont.) • C. How are sediments introduced to the flow stream? (cont.) 3. Erosion II. Stream flow over exposed soil, no plant cover or pavement, mobilizes soil particles. 4. Raindrop Energy. Raindrops striking the earth’s surface liberate soil particles for transport in sheet flow.

35. V. The fourth category of pollutant to examine is sediment. (cont.) • C. How are sediments introduced to the flow stream? (cont.) 5. Sediments residing on human created surfaces, pavement, roofs, etc., are incorporated into run-off by either sheet flow or raindrop energy. These particles tend to be fine and are purported to be associated with substantial concentrations of metals and/or synthetic organics.

36. Discussion Break Erosion is a natural process. The Clean Water Act does not specifically recognize it as such. What kind of language, in a law, would correctly differentiate between natural and unnatural erosion?