Sediment Sampling Protocols

Transcription

1 Sediment Sampling Protocols February 2017 Sampler Training Workshop Thomas Seal, ES III Watershed Monitoring Section (WMS) Water Quality Assessment Program DEAR Tallahassee

2 Sediment Sampling in Large and Small Lakes in the Status Network In the annual Status Network, ideally 180 sediment samples would be collected (90 Small Lake; 15 per zone; 90 Large Lake; 15 per zone). But the annual number is less than 180, due to lack of natural small lakes in certain parts of Florida. Small Lakes are sampled in the center of open water in the lake, whereas Large Lakes are sampled at the provided latitudelongitude value.

3 FDEP SOP References for Sediment Sampling Protocols First, please read Section 6, Sediment Sampling Protocols, in the Status and Trend Network Sampling Manual. These protocols are based on the existing FDEP SOP for sediment sampling, including: Table FS , FS 1000, Table FS (equipment and construction) FS 1000 and Table FS (containers) FC 1100 and FC 1300 (cleaning) FD 1000 (documentation) FS 1000 Table (preservation/holding times)

4 List of Sediment Analytes to be performed by the FDEP Laboratory Metals: Aluminum*, Arsenic, Cadmium, Chromium, Copper, Iron*, Lead, Total Mercury, Nickel, Silver, Zinc (* = normalizing elements) Nutrients: Nitrogen (TKN), Total Phosphorous, Total Carbon, Total Organic Carbon Organic Contaminants: PAHs, PCBs, and pesticides will be analyzed in Status Network sediments in 2017.

5 Equipment Selection Use the appropriate sampling equipment approved by the WMS QA Officer. Dredges are useful in either soft (mud/muck) or hard (sand/gravel) sediments. Coring devices are useful in shallow (wadeable) waters.

6 Dredges used in Watershed Monitoring Program Status Network Ponar Dredge Standard and Petite* * FDEP staff use the petite version Ekman Dredge

7 Dredge Devices The Ponar or Ekman dredges are the preferred devices to use in freshwater systems. When polled, most DEP samplers state they prefer the ponar. Ponar dredges useful in sandy or hard substrates Ekman dredge - useful in soft, mucky sediment With both dredges, to prevent sample washout, make sure the jaws fully close. If washout occurs (e.g., due to wedged stick), dump remaining sample and redeploy the sampler.

8 Coring Sampler Device Use corer made of material such as stainless steel or an approved plastic material. Use plastic sealing caps at both the top and bottom as you remove the corer from the sediment. Multiple cores (4 or more) will need to be collected to acquire enough sediment for analysis.

9 Sampling Protocols Sample surface water before sediments. Collect a minimum of three grabs at each site, and collect enough sediment to fill the provided 500 ml sample jar at least 2/3 s full. If you are having trouble collecting a sediment sample (e.g., rocky bottom, vegetation), contact the project manager or QA officer. Note this on your field sheet.

10 Sampling Protocols If necessary, siphon water out of the sampling device with a sampling syringe and plastic tubing. Remove debris with Teflon forceps. With the provided white HDPE (high-density polyethylene) scoop, collect the top 3-5 cm of sediment from the dredge in order to focus on the bioactive layer.

11 Siphoning water out of Petite Ponar Sampler

12 Remove debris with Teflon forceps

13 Remove debris with Teflon forceps

14 Place top 3-5 cm of cored sediment into sample jar. These rootlets are a good example of what should be removed with forceps.

15 Fill 500 ml sample jar 2/3 full. Seal lid to jar by wrapping somne black electrical tape to prevent water leakage.

16 In 2017 Status Lakes, you will have 1 L jars and fill ½ full

17 Sampling Protocols If sample is flocculent ( soupy ), you may go deeper (>5 cm) with the HDPE scoop. Note this on field sheet. Store samples on ice for shipment to DEP Central Laboratory in Tallahassee.

18 Use of Status Network Sediment Data Status Network sediment data are evaluated with two statistical tools. First, WMS staff use a geochemical normalization tool to distinguish sediment metal background levels from elevated values. Al and Fe data are normalized to other metals data to confirm contamination. Second, FDEP WMS staff use biological sediment guidelines to judge if the metals are elevated enough to cause biological harm. These are cited in Department-approved Rule These results complement WMS water quality data in the biannual Integrated Report, submitted to USEPA by DEAR staff.

19 Geochemical normalization technique using Aluminum to distinguish background copper levels from elevated values Al Cu Natural background of copper vs aluminum in clean Florida sediments Source: DEVELOPMENT OF AN INTERPRETIVE TOOL FOR ASSESSMENT OF METAL ENRICHMENT IN FLORIDA FRESHWATER SEDIMENT (FDEP, 2002)

20 FDEP Biological Sediment Guidelines The Department uses two biological guidelines for each sediment contaminant: a lower guideline, the Threshold Effects Concentration (TEC), and a higher guideline, the Probable Effects Concentration (PEC). A value below the TEC indicates a low probability of harm occurring to sediment-dwelling organisms. Conversely, sediment values above the PEC have a high probability of causing biological harm. For example the Cu TEC is 32 mg/l ; the PEC is 149 mg/l. Sediment sample #5, at 400 mg/l, exceeds the PEC. One reason for Cu exceedances in Florida lake sediments is repeated use of Cu herbicides for aquatic weed application.

21 Status Network Small Lake sediment samples (n = 441) collected from years

22 FDEP Sediment Publications 1988 A Guide to the Interpretation of Metals Concentrations In Estuarine Sediments 1989 Journal article in Environmental Science and Technology 1990 Journal article in Estuaries 1994 Florida Coastal Sediments Contaminants Atlas 1994 Approach to the Assessment of Sediment Quality in Florida Coastal Waters (estuarine/marine sediment guidelines) 1995 Journal article in Environmental Management on national sediment quality guidelines 1996 Journal article in Ecotoxicology on the development and evaluation of sediment quality guidelines for Florida coastal waters 2002 Development of an Interpretive tool for Assessment of Metal Enrichment in Florida Freshwater Systems (Excel tool) 2003 Sediment Quality Consensus Guidelines published in Development and Evaluation of Numerical Sediment Quality Guidelines for Florida Inland Waters (freshwater sediment guidelines)

23 Contact Information Thomas Seal, NWFWMD/SJRWMD/Alachua County Project Manager USGS North Florida river Gaging Contract Manager FDEP Watershed Monitoring Section, Water Quality Assessment Program Division of Environmental Assessment and Restoration 2600 Blair Stone Road, MS 3525 Tallahassee, FL Web Address for FDEP geochemical/biological sediment guideline documents: Pertinent reading!