Presentation on theme: "Measuring Water Pollution A Quick Overview. How do you measure the quality of a moving, ever changing fluid medium?"— Presentation transcript:
Measuring Water Pollution A Quick Overview
How do you measure the quality of a moving, ever changing fluid medium?
Two Basic Approaches: n TECHNOLOGY- BASED LIMITS: Use a certain treatment technology (BPT, BAT, MACT, BPJ) to achieve a given quality of effluent n WATER QUALITY- BASED LIMITS: Quantitative relationship between inputs and quality (LD 50, NOEL)-- dose/response risk assessment, hydrology, mass balance
The Conventional Pollutant Measures: n Oxygen (BOD, COD, DO) n Solids content (TSS, Conductivity, Secchi disk, settleable solids) n Nutrients (phosphorus, nitrogen) /Algae/Eutrophication n Acidity (pH) n Bacteria (e.g., fecal coliform) n Temperature
Oxidizing (Oxygen-Using) Reactions n Fire n Metabolism of humans and animals n Fate of pollutants in water n C in fuel combines with atmospheric O 2 n carbon-bearing organic compounds oxidized to CO 2,water, energy n pollutants are oxidized, depleting O 2 in water
Measures of oxygen in water: n Dissolved oxygen (DO)--time and space variables, dilution n Biological oxygen demand, five days (BOD 5 ) n Chemical oxygen demand (COD) n Sediment oxygen demand (SOD)
Oxygen and other pollutants may vary according to: n Fluctuations in inputs (lagged) n Time of day (day-night) n Time of year (summer-winter) n Water temperature (thermal stratification) n Stream flow –Which in turn varies with land clearance/impervious cover, storm events, seasonal variations, channel structure, etc.
Effects of sediment loading n Destruction of spawning beds n Adsorption and transport of other pollutants n Reduced light penetration, aquatic vegetation n Greater nutrients loadings, oxygen demand n Interference with navigation, flood control, recreation, industry
Effects of nutrient loadings (N, P measured by Chlorophyll a, Secchi, algal species) n Algae blooms n DO changes, fish kills n Shift of trophic status toward eutrophic n Drinking water impairment (direct and indirect) n Aesthetics (color, clarity, smell) n Uptake and release of toxics
Effects of acidification (measured in pH--log scale) n Direct kill of living things n Shift toward acid-tolerant species n Mobilization (dilution, desorption) of metals and other toxics
What about toxics?
Impacts of toxics n Acute mortality (instant death) n Chronic illnesses (e.g., cancer) n Reproductive and developmental toxicity (hormone mimics) n Persistence over space (toxaphene) and time (PCBs); or transformation (DDT to DDE, PCB dechlorination, methyl mercury) n Storage in reservoirs (sediment sinks)
Some approaches to toxics parameters n Chemical levels (water, sediment) n Ability to support designated uses n Ability to support beneficial uses n Fish advisories n Historical baselines n Background levels n Narrative criteria (no toxics in toxic amounts)
Indices Bring diverse measurements together into a single-number value
Ecosystem approaches n Look at interactions of living and nonliving parts of the ecosystem (whats an ecosystem?) n Try to identify stresses and responses n Holistically integrate physical, biological, and social aspects of the area in question
Social Indicators n Stewardship n Sustainability n Stakeholder Involvement n Etc., etc. (what is the good society?)