Hydrology and Water Quality. Water. Water 9/11/2018. Molecular Water a great solvent. Molecular Water

Transcription

1 Hydrology and Water Quality Water Molecular Water Exists as an equilibrium But equilibrium altered by what is dissolved in it Water Molecular Water a great solvent In reality, water in the environment is a solution and a suspension Solutes, colloids, and particulates from many sources found in water WHERE DO THESE ADDITIONS COME FROM? 1

2 Water cycles in the environment = % Hydrologic Cycle Leaving 0.038% The Earth s Freshwater Fresh water is a finite natural resource Majority of Earth's water is in oceans which is not readily potable Water consumption in the U.S./world is increasing Constituents of the solution we call freshwater are the result of Geology Geography/Climate Location Use Diagram from 90s 2

3 km 3 = 264,172,051,242 gallons The Environmental Technologist s Understanding Of Water Interacts with soil and rock at and below Earth s surface geology affects water, water affects geology rainfall and topography affect water s interactions with geology within watershed Interacts with organisms (like transpiration) including human technology and population Weather and climate affect the availability of water in the country Since humans rely on water, ET seeks to provide it, protect it, and control it Rock Formations Not as solid as you think Can be porous porosity = % occupied by voids spaces where water may move, reside Can be permeable (permeability) water can (slowly) flow through the pore spaces Can be soluble develop solution cavities, affect water chemistry Otherwise solid rock possesses fractures, fissures, faults that allow water to enter 3

4 Surface Water Reminder: What is surface water? creeks, streams, rivers Impoundments (constructed) Wetlands, ponds, lakes, oceans Ridge line Surface Water Terms headwaters Point of concentration Watersheds and subwatersheds Stream order 4

5 Watershed Concerns Rainfall effects Human use Drinking Industry Wastewater assimilation Erosion Design of stormwater management structures Design of drinking water reservoirs Flooding Rain Of importance to environmental technologists: How much total inches in single event How often number of events How intense rainfall total per hour All are described and modeled for prediction purposes Example: hydrographs -- 5

6 Water Quality Categories of Constituents: Type and concentration determine water quality Physical constituents - characteristics Chemical constituents Inorganics Organics Biologic constituents Turbidity Suspended solid materials Clay, silt, organic matter, microbes Natural sources erosion, living things Anthropogenic sources organic enrichment, development/construction 5 TU noticeable 6

7 Turbidity Affects drinking water treatment and aesthetics Significantly affects aquatic life Suspended load - Transparency and primary productivity Habitat Loss Bed load - Silting in Affects benthic community Temperature Significantly affects aquatic life Optimum temperature Coldwater versus warmwater species Too warm a temperature can stimulate growth of undesirable populations Acclimatization Quick changes devastating Relationship to dissolved oxygen concentration Humans like drinking cold water! 7

8 Color, Taste, and Odor Primarily drinking water or aesthetic issue Drinking water must look, taste, and smell good even if it is completely safe to drink Laundry issues Various measurements are used In aquatic systems, color is aesthetic issue and possibly a transparency one Dissolved Oxygen Concentration Ecologically, one of the most important chemical parameters of water quality Oxygen gas does dissolve in water mg O 2 /l Saturation is temperature dependent Most life on planet adapted to oxygen Important to aerobic metabolism Without it, no metabolism Aerobes compete for DO DO directly related to aeration and temperature Biochemical Oxygen Demand Utilization of oxygen by aerobic microorganism community as they metabolize organic materials Organics decomposed (oxidized) to CO 2 and H 2 O, theoretically Oxygen availability limits what can be done aerobically Organic concentration directly impacts BOD Affected by temperature 8

9 Biological Oxygen Demand A conventional pollutant lack of control significantly impacts water quality BOD has been controlled by municipal sewage treatment Biological Oxygen Demand Ecological Effects Waste Assimilation in Waterways It s real if the waste is Biodegradable Pollutant loading not too strong and not too often Water flow and aeration provide dilution, volatilization, and O 2 for aerobic biodegradation Persistent chems do not assimilate Dilute Are lost to sediment only to reappear Note the BOD example 9

10 Types of BOD Ultimate BOD BOD L mg/l of O 2 needed to completely oxidize organics strong sewage needs more O 2 5-day BOD BOD 5 - a management tool Change in DO during 5-day, 20 C incubation in dark 1 mg/l natural background >10 mg/l significantly organic enriched Dilution Seeding Solids Suspended or dissolved Suspended solids contribute to turbidity Dissolved solids also related to the parameters of hardness, alkalinity, nutrients Measurements: Total Suspended Solids ml/l, mg/l Turbidity! Total Dissolved Solids mg/l Impacts drinking water treatment and aquatic life Undesirable Dissolved Solids 10

11 Hardness and Alkalinity Measure of Ca +2 and Mg +2 (hardness) and buffering capacity (alkalinity) of water Both naturally occurring Reported as mg CaCO 3 /l Hardness presents challenges for drinking water use and delivery Related parameter acidity, has implications for drinking water delivery and taste Implications for aquatic life Nitrogen and Phosphorus Compounds Ammonia Toxicity and BOD Nitrate Plant nutrient Phosphate Often a limiting nutrient Ammonia 11

12 Nutrient Enrichment ph Naturally occurring and controlled Human sources must be controlled or devastating effects on aquatic life A conventional pollutant 12

13 Residual Chlorine Different from Cl -, a naturally-occurring ion Added to drinking water for disinfection and protection during delivery Disinfection by-products Significant implications for aquatic life Toxics Organics And Inorganics heavy metals pesticides Hydrocarbons including chlorinated hydrocarbons miscellaneous synthetics Biologic Constituents of Water Microbes Virus Bacteria Protozoa Algae Fungi Invertebrates Vertebrates Presence or absence gives indication of water quality Lack of diversity can be a sign of poor water quality 13

14 Indicator Organisms Fecal coliforms Community of organisms that inhabit the colons of humans (and other warm blooded animals) Not all bad but indicate presence of contamination with fecal wastes, likely human Greater the number, the greater the probability of illness-causing organisms present Indicator Organisms Protection and disinfection of drinking water the single most significant factor in extending human life span Nearly doubled since the advent of drinking water treatment Water Pollution In general terms, water is considered to be polluted when it contains enough foreign material to render it unfit for a specific beneficial use, such as for drinking, recreation, or fish propagation. 14

15 Urban Hydrologic Cycle Water use: public, industrial, commercial Wastewater treatment Water treatment Water source: Streams, rivers, lakes, groundwater Sources of Water Pollution Point source discharges Non point (dispersed) sources Discharge of dredge or fill materials % Impaired River Miles U.S. 15

16 Causes of River Impairment Point Source Discharges Municipal and industrial effluents Contaminants present in varying concentrations Actual contaminants present a function of source Contaminant concentrations regulated based on numeric values, physical characteristics, or toxicity limits Point Source Discharges Sewage treatment plants Steel mills Paper mills Chemical manufacturers Automakers Textile manufacturers Others! 16

17 Non Point Sources Urban runoff Major source Construction sites Septic systems Non Point Sources Agricultural use and runoff Non-Point Sources- Mining 17

18 Thermal Pollution Cooling water Sources mostly under control using cooling ponds and towers May result from uncontrolled point sources, non-point sources, and habitat alteration Non-Point: Soil Erosion Sediment moved by wind or water Sheet erosion Stream erosion Control Vegetative cover Soil erosion and sediment control plans Detention Special Consideration for Lakes Eutrophication Natural process but accelerated culturally by anthropogenic nutrients Oligotrophic Mesotrophic Eutrophic Advanced wastewater treatment Significant sources remain 18

19 Lake Pollutants Organics impact oxygen profile Nutrients impact plant growth, organic production, and therefore oxygen Silts/sediments impact plant growth and temperature via shallowing Groundwater Pollution GW quality generally good right out of the ground Natural filtration of particulate But also inclusion of minerals, hardness But, in some areas, impacted by Land disposal Industrial municipal Deep well waste management Accidental spills USTs Septic systems Abandoned wells Mining and petroleum Overuse groundwater mining Agricultural chemicals Urbanization 19