Standard Operating Procedure Secchi Depth

Transcription

1 Standard Operating Prcedure revised January 8, 2017 Secchi Depth Page 1 f 5 Standard Operating Prcedure Secchi Depth Table f Cntents 1 POINT OF CONTACT OBJECTIVE DEFINITIONS AND ABBREVIATIONS OVERVIEW SOURCES MATERIALS AND EQUIPMENT METHODS Preparatin Field Cllectin and Prcessing Sample Strage Labratry Analysis TROUBLESHOOTING / HINTS DATA PROCESSING AND STORAGE REFERENCES Quick Sheet Secchi Depth POINT OF CONTACT NAME: Peter Linderth, Save the Sund / CFE, Water Quality Prgram Manager ADDRESS: 545 Tmpkins Ave, 3rd Flr, Mamarneck, NY plinderth@savethesund.rg PHONE: OBJECTIVE Determine the clarity f the water as represented by Secchi depth. Frequency f sampling and daily rder f events are specified in the UWS Sampling Plan SOP. 3 DEFINITIONS AND ABBREVIATIONS Embayment: A recess in a castline r an indentatin ff a shreline which frms a bay. In Lng Island Sund, the names f embayments ften include the wrds Harbr (27%), River (23%), Cve (19%), Bay (10%), Creek (10%), and Pnd (7%); with a few including the names Brk, Gut, Inlet, r Lake. Field Team: Persn r grup f peple wrking tgether t sample a statin.

2 Standard Operating Prcedure revised January 8, 2017 Secchi Depth Page 2 f 5 Mnitring Grup: The grup cnducting the field wrk. Sectin: The reprting regins fr the embayment reprt card. Each sectin must include a minimum f three statins. Sectins will be assigned a unique name by the UWS; examples are included belw. Number f Sectins Name f Sectins whle inner uter inner middle uter Abbreviatins fr Sectins W I O I M O Site: The whle embayment, as defined by the UWS list. Each site has a unique three letter cde assigned by the UWS; fr example, Little neck Bay, NY is LNE. SOP: Standard perating prcedure; this dcument is a SOP. Statin: The lcatin where samples are cllected, identified by a GPS lcatin. UWS: Unified Water Study UWS Crdinatr: The persn designated as the pint f cntact fr the UWS. UWS Scientific Advisr: Estuarine r water quality scientists designated as advisrs t the UWS. 4 OVERVIEW Secchi disks are used by many mnitring prgrams as they prvide an inexpensive and quick methd fr evaluating the clarity f the water. Secchi discs range in size and material. The disc is typically divided int fur alternating black and white quadrants, thugh discs can alternatively be all white; either is fine fr the UWS. Secchi discs used in freshwater systems are typically 20 cm in diameter, while Secchi discs used in pen water (deep) marine systems are typically 40 cm t 50 cm in diameter, thugh they can range in sizes frm 5 cm t 1 m. The size is determined by the expected Secchi depth fr the system. Larger sizes are used in clearer waters, where the disappearance frm view may be due t the size f the disc versus the clarity f the water. 5 SOURCES These prcedures are based n the EPA Vlunteer Estuary Mnitring Manual (EPA, 2007) and fllws methds used in the EPA Natinal Castal Assessment (EPA, 2001). The EPA Vlunteer Estuary Mnitring Manual (EPA, 2007) prvides a wealth f specific data fr mnitring grups. All grups shuld refer t the EPA manual fr specific guidance. 6 MATERIALS AND EQUIPMENT Weighted Secchi disc

3 Standard Operating Prcedure revised January 8, 2017 Secchi Depth Page 3 f 5 Rpe with depth designatins measured frm the surface f the Secchi disc, when cnnected. Yu may use a metered line. Alternatively, yu may use a rpe and cnnect a meter tape t the rpe fr determining depth. 7 METHODS 7.1 Preparatin Examine the Secchi disc fr damage; check that the weight is securely attached t the Secchi disc. Check that the attachment fr the rpe is secure. Chipped sectins n the disc are acceptable if they d nt affect yur ability t see the disc when underwater. Chips can be repaired by painting with the apprpriate clr r using electrical tape f the apprpriate clr t cver the chips. Examine the line fr wear r damage. At least nce a mnth, measure the increments n the line t ensure line has nt stretched r shrank. Check ut the Secchi disc simulatr. This website prvides a chance t test yur Secchi depth reading skills: This site is hsted by the Maine Vlunteer Lake Mnitring Prgram. 7.2 Field Cllectin and Prcessing 1. Check t make sure that the Secchi disk is securely attached t the measured line. 2. Lean ver the side f the bat and lwer the Secchi disk int the water. a. Sampling shuld ccur n the shady side f the bat. If there is n shade, r yu are sampling frm shre, keep yur back t the sun t blck glare. b. D nt wear sunglasses. 3. Lwer the disk until it disappears frm view. Lwer it an additinal ne third f a meter and then slwly raise the disk until it just reappears. Mve the disk up and dwn until the exact vanishing pint is fund. 4. Recrd the depth f the vanishing pint t the nearest 5 centimeters n the data sheet. It can be helpful t pinch the line exactly at the waterline befre retrieving fr measurement. 5. Repeat fr a ttal f at least three readings and recrd each. 6. If the range f measurements fr the three readings is greater than 0.5 m, repeat the entire measurement prcess, raising and lwering the disk several times arund the vanishing pint. If the Secchi disk is still visible n the bttm, recrd the Secchi depth as BV fr bttm viewable. Be sure t recrd the depth n the data sheet. If mre than ne persn is available, each persn shuld make a measurement and the results shuld be averaged.

4 Standard Operating Prcedure revised January 8, 2017 Secchi Depth Page 4 f Sample Strage Nt applicable. 7.4 Labratry Analysis Nt applicable. 8 TROUBLESHOOTING / HINTS Secure the free end f the line t a cleat r piling t avid lsing the Secchi disc verbard. Use the shady side f the bat. D nt wear sunglasses. Add mre weight in strng currents if needed. Always carry a cpy f this SOP and the relevant parameter-specific SOPs. Print ut the quick sheets fr relevant SOPs t use as a reminder in the field. D nt laminate these as yu will want t add ntes. A plastic page-prtectr taped clse can be used t keep these sheets dry. 9 DATA PROCESSING AND STORAGE The UWS crdinatr will be the custdian f the finalized data files. The UWS crdinatr will maintain a database which includes the unique site cdes, sectin cdes, and statin cdes fr the embayment. Each unique statin cde will be affiliated with the crrespnding GPS fr the statin. The mnitring grup is respnsible fr btaining data, entering data int the UWS data template, and delivering the data t the UWS crdinatr. The mnitring grup is respnsible fr assuring that the crrect unique statin ID assigned by the UWS is prperly matched with the lcal rganizatins statin ID cdes. Bth cdes (mnitring grup s statin cde and UWS unique statin ID) will be entered int the data template, alng with the GPS crdinates. 10 REFERENCES EPA, 2007, Vlunteer Estuary Mnitring, A Methds Manual, Secnd Editin. Orhrel Jr., R.L., Register, K.M. (Eds.). The Ocean Cnservancy & EPA. 396 p. EPA, U.S Natinal Castal Assessment: Field Operatins Manual. U. S. Envirnmental Prtectin Agency, Office f Research and Develpment, Natinal Health and Envirnmental Effects Research Labratry, Gulf Eclgy Divisin, Gulf Breeze, FL. EPA 620/R-01/ p.

5 Standard Operating Prcedure revised January 8, 2017 Secchi Depth Page 5 f 5 11 Quick Sheet Secchi Depth Preparatin Examine the Secchi disc fr damage; check that the weight is securely attached t the Secchi disc. Check that the attachment fr the rpe is secure. Chipped sectins n the disc are acceptable if they d nt affect yur ability t see the disc when underwater. Chips can be repaired by painting with the apprpriate clr r using electrical tape f the apprpriate clr t cver the chips. Examine the line fr wear r damage. At least nce a mnth, measure the increments n the line t ensure line has nt stretched r shrank. Check ut the Secchi disc simulatr. This website prvides a chance t test yur Secchi depth reading skills: This site is hsted by the Maine Vlunteer Lake Mnitring Prgram. Field Cllectin and Prcessing 1. Check t make sure that the Secchi disk is securely attached t the measured line. 2. Lean ver the side f the bat and lwer the Secchi disk int the water. a. Sampling shuld ccur n the shady side f the bat. If there is n shade, r yu are sampling frm shre, keep yur back t the sun t blck glare. b. D nt wear sunglasses. 3. Lwer the disk until it disappears frm view. Lwer it an additinal ne third f a meter and then slwly raise the disk until it just reappears. Mve the disk up and dwn until the exact vanishing pint is fund. 4. Recrd the depth f the vanishing pint t the nearest 5 centimeters n the data sheet. It can be helpful t pinch the line exactly at the waterline befre retrieving fr measurement. 5. Repeat fr a ttal f at least three readings and recrd each. 6. If the range f measurements fr the three readings is greater than 0.5 m, repeat the entire measurement prcess, raising and lwering the disk several times arund the vanishing pint. If the Secchi disk is still visible n the bttm, recrd the Secchi depth as BV fr bttm viewable. Be sure t recrd the depth n the data sheet. If mre than ne persn is available, each persn shuld make a measurement and the results shuld be averaged.