Presentation is loading. Please wait.

Presentation is loading. Please wait.

Turbidity and Chlorophyll Lecture 3. YSI (Yellow Springs Inc) https://www.ysi.com/ysi/Products.

Similar presentations


Presentation on theme: "Turbidity and Chlorophyll Lecture 3. YSI (Yellow Springs Inc) https://www.ysi.com/ysi/Products."— Presentation transcript:

1 Turbidity and Chlorophyll Lecture 3

2 YSI (Yellow Springs Inc) https://www.ysi.com/ysi/Products

3 YSI sensors

4 HACH - Hydrolab

5 Some Hydrolab sensors

6 Turbidity Measure of suspended particles in water – can include inorganic (sediments) as well as organic (bacteria, plankton). High turbidity reduces light transmission (by both absorption and scattering), i.e. larger light attenuation coefficient (K). Can measure with secchi disk (secchi depth, cm) Can measure by weight (total suspended solids (TSS, mg/L) Can measure with turbidimeter = nephelometer (NTU)

7 NTU Nephelometric Turbidity Units (NTU) dete ctor mirror A more popular term for this instrument in water quality testing is a turbidimeter. However, there can be differences between models of turbidimeters, depending upon the arrangement (geometry) of the source beam and the detector. A nephelometric turbidimeter always monitors light reflected off the particles and not attenuation due to cloudiness. In the United States environmental monitoring the turbidity standard unit is called Nephelometric Turbidity Units (NTU)geometryattenuationUnited Statesenvironmental monitoringNephelometric Turbidity Units Nephelometer comes from the Greek word for cloud, nephos,

8 Turbidity standards Formazine based (carcinogenic) – typically 4000NTU stock diluted. Need to test against NIST standards. Precipitates unless stirred constantly. AMCO beads – non-toxic. Long shelf life. More expensive. Slightly different scattering properties. tandards.php

9 Some NTU numbers DI or RO water (approx 0 NTU) Tapwater (<0.3NTU) Surface waters clear (<5NTU) Surface waters visibly turbid (10-50NTU) Silted waters from erosion (up to 1000NTU) Problems for fish/organisms (>50-100NTU) Protect benthic seagrasses (<5-10NTU)

10 Light Limitation is the Principal Determinant of SAV Distribution Water Quality drives light limitation Secchi depth (m) or attenuation coefficient (K d ) in 1/m Light-limitation depends on water quality Light is absorbed (a) and scattered (b) by water+TSS+color+chl a From mathematical models of light absorption and scattering a direct link between water quality and light available to SAV can be calculated. TSS

11 U.S. Coastal States Water-Quality Criteria for Turbidity Patrick Biber - Univ. of North Carolina, Chapel Hill RegionStateCriteria for saltwaters (surface WQ standards)Year Best Numerical Criterion + Exceed 25NTU 1 Exceed 5NTU 2 NEConnecticutnot to exceed natural origin, use BMPs (FW <5NTU over backgrnd)1997 NEDelaware<10NTU above background natural turbidity NEMaineno turbidity criteria2000 NEMassachussettsfree from turbidity that aesthetically objectionable or impair any use1993 NENew Hampshire<10NTU above background natural turbidity NERhode Island<5NTU above background (SA), <10NTU above background (SB, SC) CENMarylandnot exceed 50NTU monthly avg, not exceed 150NTU point msr1995? CENNew Jersey<10NTU 30 day avg, <30 NTU point msr CENNew Yorkno increase that will cause substantial visible contrast to natural conditions1999 CENVirginiano turbidity criteria1997 SEFlorida<29NTU above background natural turbidity SEGeorgiafree from turbidity that results in a substantial visual contrast due to man-made activity2000 SENorth Carolinanot exceed 25NTU, if natural background >25 NTU no increase over background permitted SESouth Carolinanot exceed 25NTU provided existing uses maintained1976?25020 GOMAlabama<50NTU above background natural turbidity2002? GOMLouisianaestuarine lakes, bays, bayous <50NTU GOMMississippi<50NTU above background turbidity beyond a 750ft mixing zone at time of discharge GOMTexasno substantial and persistent changes from ambient conditions1997 PACAlaskanot exceed 25NTU, not increased Ksecchi by more than 10% PACCaliforniaWastewater to oceans = 75NTU 30 day avg, 100NTU 7 day avg, max 225NTU point msr PACOregon<10% cum increase relative to upstrm control location, except in emergency/construction w BMPs2001 PACWashington <5NTU above background when <50NTU, <10% above background otherwise (AA, A); <10NTU above background when <50NTU, <20% above background otherwise (B, C) HAHawaiiEstuaries and embayments = geom mean <1.5NTU, 90% of time <3NTU, 98% ot time <5NTU1992? NATFEDERALno turbidity criteria NB: Hawaii only state that has turbidity criteria that appear to be fully protective of seagrasses to depths >1m + Numerical criterion based on background of 0 NTU 1,2 Turbidity levels associated with minimum light requirements for seagrass at 1m depth in 1. North Carolina and 2. Chesapeake Bay

12 Calibration Always check expiration dates. Make Formazin solutions fresh EACH time – check against a standard in turbidimeter before use. Always check 0 NTU first (DI water) Always use a standard higher than max value expected (e.g. 10 NTU or 100 NTU) ALWAYS check for AIR BUBBLES – this is the major source of error or bad data.

13

14 Chlorophyll Fluorescence Derived from light NOT used for photosynthesis. A proxy for phytoplankton concentration (= abundance of cells) Affected by amount of photosynthesis happening as well as cell density. Can vary widely over the course of a day FOR THE SAME AMOUNT OF CELLS!!!

15

16

17 Photosynthesis

18 Chloroplast

19

20 Chlorophyll Excitation Each quantum of light absorbed by a chlorophyll molecule rises an electron from the ground state to an excited state.

21 Light reaction – Z scheme

22 Photosynthesis 3%

23 Light Energy “Usage”

24 Light Rct and Fluorescence IN VIVO - LIVING CELLS: Not all light is used for photosynthesis, i.e. for electron transport in the light reaction. Depending in species, conditions, physiological state, some or most of light is converted to fluorescence (measurable) or heat (“not” measurable) IN VITRO – chl extracted with acetone: None of the above matters – fluorescence is directly proportional to chl concentration

25 METHODS – chl extraction EPA standard method 445 (fluorometric) or ESS150 (spectrophotometer) are for phytoplankton. Grind sample in solvent (90% acetone) in dark and keep cold (chl is easily destroyed!) Allow to extract overnite in fridge (4 0 C) Centrifuge or filter to remove “particles” Read Abs or Flr on machine. [Acidify with HCL – read phaeophytin and used in calculations] [Other solvents include methanol, dimethylformamide (DMF), fluorocarbon ionic surfactant Zonyl FSA, etc.]

26 Turner TD700 fluorometer Sensitive – use for low concentrations (very faint green color). Best for phytoplankton. Configuring the Turner Designs Model TD-700 Fluorometer for Method Method Your fluorometer should be equipped with the following Turner Designs optical filter kit (or equivalent): Optical Kit: PN: Excitation filter: R color specification 5-60 Emission filter: R color specification 2-64 Lamp: Daylight White Lamp

27 Turner TD700 fluorometer Sensitive – use for low concentrations (very faint green color). Best for phytoplankton. Configuring the Turner Designs Model TD-700 Fluorometer for Method Method Your fluorometer should be equipped with the following Turner Designs optical filter kit (or equivalent): Optical Kit: PN: Excitation filter: R color specification 5-60 Emission filter: R color specification 2-64 Lamp: Daylight White Lamp

28 THEREFORE In water quality monitoring chl fluorescence is a RELATIVE indicator of change in phytoplankton population abundance. IT IS NEVER AN ABSOLUTE MEASURE! The only “absolute” measure is to take a water sample, filter to concentrate, extract with solvent (e.g. 90% acetone), determine sample chl concentration and back-calculate to in-water chl concentration after correcting for volume filtered.

29 Another note Usually chl samples are frozen after filtering, and run weeks or months later. THIS MAY BE A PROBLEM? A recent study in Long Island showed about a 30% decrease in extracted chl concentration of samples frozen longer than 2 weeks compared to the SAME samples if extracted immediately. NUTRIENT MANAGEMENT STRATEGIES ARE BASED LARGELY ON CHL NUMBERS…

30 Lab Check turbidity standards. Calibrate NTU+ sensor and read water samples. Optical sensor maintenance. Test chl flr sensor with fluorophore


Download ppt "Turbidity and Chlorophyll Lecture 3. YSI (Yellow Springs Inc) https://www.ysi.com/ysi/Products."

Similar presentations


Ads by Google