Objective Understand the regulations concerned with water and water quality (CWA, SDWA) Identify most common Sources of Pollutants Define Water Quality Standards & Water Quality Criteria Understand Basic Premise of Water Quality Monitoring in the field: What parameters to sample? Where and when to sample? Sampling Techniques, & Field safety Lab sessions (2-3 sessions): Intro to Field monitoring Equipment's use and calibrations & Field Measurements
Major Fedral Regulations Governing Water in the US Clean Water Act (CWA): Approved by Congress in 1972 into law Safe Drinking Water Act: Approved by Congress in 1974 into law Enforced by U.S. Environmental Protection Agency (EPA or sometimes USEPA) Established in 1970. Put into action by States and Tribes through established water quality Standards.
EPA Safe Drinking Water Act:SDWA Concerned with public health associated with safe drinking water. Ensure that water is protected “from source to tap.” SDWA Regulates: - Public Water Treatment Systems that treat, store, and distribute water to consumers -Protect sensitive groundwater/well water and surface water sources of drinking water.
EPA Clean Water Act: CWA The Clean Water Act (CWA) Regulates discharges of Pollutants into Waters of United Sates: Rivers & Streams Lakes Wetlands (generally include swamps, marshes) Marine Environment Broader Regulation than SDWA: Ensure clean, fishable and swimmable water, as well as protecting marine habitat.
Other Regulatory Agencies Working with EPA US Geological Survey (USGS) US Army Corps of Engineers US Department of Agriculture US Fish and Wild Life US Department of Transportation US Department of Interior These agencies may add other regulatory criteria to a permit depending on where the polluted water is discharged
Source of the Pollutants Nonpoint Source (NPS) Pollution - Pollution that, comes from many diffuse sources. Snow melts or rainfall runoff on large surface areas picks up and carries away natural and man made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters, and even our underground sources of drinking water. Point Source of Pollution (PS) – Pollution that comes from a single source -such as pipes or man made ditches that discharge pollutants into waters of the United States. Examples : -Discharges from municipal sewage plants -Industrial facilities, - Construction Sites Storm water run-off - Storm drains in urban areas - Fish farms/Cattle farms/Croplands - Ships/oil Tanker
Non-Point Source Pollution Sources Image from EPA
Water Quality Standards (Enforced!) Safe Drinking Water Act (SDWA) has established strict National enforceable water quality Standard for Drinking water that must be enforced at State levels. Assigns MCLs =Maximum Contaminant limits allowed for pollutants in drinking water Goal= achieve zero to low contaminant limits such that no adverse human health effect is expected.
Water Quality Standards The Clean Water Act (CWA) makes it illegal to discharge pollutants from a point source to the waters of the United States. Section 402 of the Clean water Act creates the National Pollutant Discharge Elimination System (NPDES) regulatory program that enforces the law. Point sources must obtain a discharge permit from the proper authority (usually a state, sometimes EPA, a tribe, or a territory). Enforcable Goal= Set limits on the amount of various pollutants that a source can discharge in a given time. Not as restrictive as Drinking water Standards
Water Quality Standards-Components 1.Designated Use (DU) ; How public uses the water body 2. Water Quality Criteria: condition in the water body that support Designated use. e.g. concentration of pollutants, Temperature, pH, Turbidity, Toxicity, etc... 3. Anti-degradation Policies developed by states or tribes: ensure high quality water is maintained by establishing a set of rules for activities that could affect/degrade the quality of water.
Regulatory Designations Assigned to Water Use Drinking water (regulated under SDWA) -Treated /Untreated Water-Based Recreation (regulated under CWA) Fishing/eating (CWA) Aquatic Life/Aquatic habitat (CWA) Agriculture water supplies (CWA) Industry water supplies (CWA)
Water Quality Criteria (WQC) 1. Narrative standards Most states and tribes require all surface waters to be free of oil, floating debris, odor, color and substances known to be toxic in human and aquatic life.. 2. Numeric Standards usually parameter specific, such as level of dissolved oxygen, pH, turbidity, Nitrogen, phosphorus, heavy metals such as mercury and synthetic organics like PCB, Dioxin etc… Numeric Standards have MCLs for maximum contaminant limits allowed under CWA
WQS: Numeric Criteria Regulatory agencies assign several numeric criteria that are established for each pollutant dependent on Water Source Aquatic life: short term effect (acute toxicity) and long term effect: chronic toxicity-Generally numerical value established for chronic toxicity limits are more stringent than for acute short term effect. Fresh water vs. Salt water: for example copper in more toxic in marine water; while cadmium is more toxic in fresh water Most human health criteria-is based on chronic except for pathogens. e.g Fecal coliform should be 0 in drinking water.
Water Quality Monitoring Objectives What parameters to sample? Where and when to sample? What Sampling Techniques? Field Measurements and/or laboratory samples? What Analytical Methods shall be use? These questions must be answered prior to field sampling in a Sampling and Analysis Plan (SAP) by the project management. Field Personnel must be aware of the content before any sampling can be initiated! Defendable and meaningful laboratory data depends on a well thought-out sampling plan!
What Parameters Are Commonly Measured In the Field ? Common Field Sampling Parameters are generally a combination of physical, chemical and biological indicators of water quality: -Turbidity-Chlorine (free & total) -Temperature-Specific Conductance -Dissolved Oxygen-Color -pH-Salinity -Total dissolved solids (TDS) -Indicator bacteria(sometimes)
Temperature (°C or °F) Most aquatic organisms are “cold-blooded"- which means they are unable to internally regulate their core body temperature. Therefore, temperature exerts a major influence on the biological activity and growth of aquatic organisms. Temperature also affects chemical processes in the water; Important in determining dissolved oxygen(Do), pH and conductivity as these parameters are temperature dependent. Field measurements generally conducted by Probes or liquid in glass thermometer. Temperature should near or at the background ambient (natural) water temperature
Turbidity Measures how particles suspended in water affect its clarity. Inorganics like clay and silt,(Sediments) and Organic material like algae, bacteria and plankton often cause turbidity. Erosions and runoff during storm events can increase turbidity of the receiving water body Field turbidity measurements are made with -Turbidimeters (field portable or laboratory meters) - Continuous monitoring sensors
Turbidimeters -Nephelometric optics Principle: Nephelometric turbidity estimated by the scattering effect suspended particles in water have on light detector is at 90 o from the light source Units: Nephelometric Turbidity Units (NTU) Standards are formazin or other certified material Limit of discharge to waterways ~< 50 0r <10 NTU depends on NPDES permits- drinking water or source of drinking water <0.3 NTU
Dissolved Oxygen (DO) Oxygen is produced during photosynthesis and consumed during respiration and decomposition. Generally < 3 mg/L is stressful to aquatic life. Units of measurement are: Concentration: mg/L = ppm; concentrations range 0.0 to 20 mg/L % saturation – used to determine if water is fully saturated with oxygen at a particular temperature Limits set at ≥ 5.2 mg/L for discharges into most waterbodies.
Do Measurement: probes Most common sensor Temperature sensitive (but virtually all are compensated). The probes actually consume O 2 as they work so measurements require moving water using either a built-in stirrer (typical in multiparameter sondes and BOD probes) or “hand jiggling” during the measurement. sensors are prone to fouling by algal/bacterial slimes and by silt in streams HI 9146-10 Portable D.O. Meter for Field Application
DO Measurement Colorimetric Test kit for environmental and drinking water applications–Uses a Photometer to measure colorimetric reaction employ the indigo carmine method. The reduced form of indigo carmine reacts with D.O. to form a blue product measured at 520 nm. The indigo carmine methodology is not subject to interferences from temperature, salinity or dissolved gases such as sulfide, which plague users of D.O. meters. Results are expressed as ppm (mg/L) O 2.
Free & Total Chlorine (Cl2) Measurement Colorimetric Test kit for environmental and drinking water applications (ppm range) Uses a photometer Employs the DPD Chemistry. - Free chlorine oxidizes DPD(N,N-Diethyl-p- phenylenediamine) to form a pink color measured at 515 nm- in direct proportion to free chlorine concentration -Total chlorine/chloramines (combined chlorine) oxidizes excess potassium iodide added to sample to iodine. The iodine then oxidizes DPD to pink color measures a 515nm. Results are expressed as ppm (mg/L) Free and Total Chlorine. Max Max Limit allowed in Drinking water=4 ppm
DO/Cl2 Measurements -Colorimetric Benefits of Colorimeters Easy Fast (2-10 minutes incubations) Replacement needed are ampoules (cost effective) Limitation of Colorimeters Reagents may react on unwanted parameters Reagents may be insufficiently sensitive for parameter Limited storage time of reagents May be quite different from official lab methods
Parameter: pH The pH of a sample of water is a measure of the concentration of hydrogen ions. pH determines the solubility and biological availability of chemical constituents such as nutrients (phosphorus, nitrogen, and carbon) and heavy metals (lead, copper, cadmium, etc.). pH range 6.5-8.5 is the regulatory range!
pH pH can be measured electrometrically or colorimetrically (pH paper) BUT ONLY the former technique is approved by the EPA The electrometric method uses a hydrogen ion electrode. pH meters require extensive care in handling and operation. Report to the nearest 0.1 standard pH unit
pH Probes Field probe types: Combination probes Less expensive; more rugged design Less precise Shorter life because reference solution cannot be replenished Separate reading and reference electrodes Costs more More precise; faster response time Allows user maintenance; Teflon junction and electrolyte can be replaced Image courtesy of USGS at http://www.usgs.gov/ HI 991301 Waterproof pH/EC/TDS/Temperature Meter (High Range EC)
Specific Conductance (EC)-or Conductivity Measures the ability of water to pass electric current Very useful general measure of Water Quality It is a function of dissolved substances in the water: Higher specific conductance means higher dissolved material in the water that may adversely affect the water quality. Note: Sea water already has high specific conductance due to dissolved salts! At present there is no water quality index associated with conductivity, although some values may be better than others for a particular body of water. Abrupt changes in conductivity might indicate that water or wastes are being diverted into the stream from a new source. Basic unit of measurment is µS/cm. (microsiemens/centimeter) Most commonly measured with conductivity probes meter
EC-Conductivity or Specific Conductance Principle of measurement A small voltage is applied between 2 parallel metal rod shaped electrodes, usually 1 cm apart. Measured current flow is proportional to the dissolved ion content of the water. If the sensor is temperature compensated to 25 o C, EC is called “specific” EC (EC25) Some common errors include: Not immersing the entire probe in the sample Forgetting to report as specific conductivity: i.e. reporting values without temperature correction
Total Dissolved Solids (TDS) The term TDS describes all solids (usually mineral salts) that are dissolved in water. The TDS and the electrical conductivity are in a close connection. The more salts are dissolved in the water, the higher is the value of the electric conductivity. The majority of solids, which remain in the water after a sand filter, are dissolved ions. Sodium chloride for example is found in water as Na+ and Cl-. High purity water that contains in the ideal case only H2O without salts or minerals has a very low electrical conductivity. The water temperature affects the electric conductivity so that its value increases from 2 up to 3 % per 1 degree Celsius.
Salinity - Dissolved Salts The salinity of water, how much dissolved salt is in the water, or the concentration of salt in the water. Concentration is the amount (by weight) of salt in water and can be expressed in parts per million (ppm). Here are the classes of water: Fresh water - less than 1,000 ppm (Drinking water <100 ppm) Slightly saline water - From 1,000 ppm to 3,000 ppm Moderately saline water - From 3,000 ppm to 10,000 ppm Highly saline water - From 10,000 ppm to 35,000 ppm Ocean water has a salinity that is approximately 35,000 ppm. That's the same as saying ocean water is about 3.5% salt. Sometimes, salinity is measured in different units. Another common unit is the psu (practical salinity units). Ocean water has a salinity of approximately 35 psu.