Sediment Sampling Methods & Considerations. MSC-210 Marine Environmental Sampling & Analysis Lecture 7

Transcription

1 Sediment Sampling Methods & Considerations EQUIPMENT, DECONTAMINATION, PRESERVATION, STORAGE, & TRANSPORTATION MSC-210 Marine Environmental Sampling & Analysis Lecture 7

2 Purpose of Sediment Collection Investigate sediment quality: Reservoir Source Adverse effects associated with exposure Protect sediment quality: Restore & maintain biological integrity of our Nation s waters Protect aquatic life, wildlife, and human health October 2015 CFCC MSC-210 2

3 Purpose of Standard Operating Procedures (SOPs) To ensure accurate data To provide consistent, high quality data collection To set up systematic, repeatable methods (comparison) To maintain in situ conditions To most accurately represent the sediment in question October 2015 CFCC MSC-210 3

4 Sediment Collection Devices Designed for: Volume Surface area Depth Integrity of the sample Minimize contamination Can be: Pole mounted Suspended on a winch wire Suspended on a hand-line October 2015 CFCC MSC-210 4

5 Three Main Types Grab samplers Collect surficial sediments Assessment of horizontal distribution of sediment characteristics Useful for physico-chemical and toxicity evaluations Core samplers Collect samples from thick sediment deposits Assessment of vertical distribution of sediment characteristics or entire sediment column Useful for physico-chemical and toxicity evaluations Dredge samplers Primarily used to collect benthos Cause disruption of sediment and pore water integrity Result in a loss of fine-grained sediments October 2015 CFCC MSC-210 5

6 Grab Samplers Jaws or rotating buckets Easy use & maintenance Sub-sample access Moderately priced Versatile Potential Problems?? October 2015 CFCC MSC-210 6

7 Different Grabs Smith-Mcintyre Ekman Ponar Petite Ponar Peterson Shipek Clam shell Grab Van Veen Orange Peel Bucket Shipek October 2015 CFCC MSC-210 7

8 Different Grabs Smith-Mcintyre Ekman Ponar/Petite Ponar Peterson October 2015 CFCC MSC-210 8

9 Selection of Grab Consider: Water depth Sediment depth Sediment grain size and/or type Access to sample site Type of study: Chemical analysis Grain size analysis Biota analysis October 2015 CFCC MSC-210 9

10 Grab Sample Acceptability The sampler is not overfilled Overlying water is present Sediment-water interface intact and relatively flat Desired depth achieved No evidence of sediment loss October 2015 CFCC MSC

11 Core Samplers Obtain samples for geological, biological, or chemical considerations Investigate historical input of contaminants Less disruptive Small volumes possible Used where sediment profile integrity is important Strata Sediment surface-water interface Pore water Data can be used to develop a three-dimensional map of sediments. Piston Core and the Box Core October 2015 CFCC MSC

12 Different Corers Fluorocarbon plastic or glass tube Hand corer Box corer Gravity corer Phleger corer Piston corer Vibracorer Lamont box corer October 2015 CFCC MSC

13 Core Sample Acceptability The core sampler was not inserted at an angle The core sampler was not tilted upon retrieval The core collected the required depth to meet the study objectives There was no apparent loss of sediment Including no loss of surficial fines October 2015 CFCC MSC

14 Sampling Documentation Station ID Geographic location (Lat/Long) Sample methods Sample time and date Sample number Ambient environmental measurements/observations Weather conditions Sample photograph Sample description Equipment used Personnel present Sketch of area and/or station map October 2015 CFCC MSC

15 Sampling EPA recommendations for: Subsampling Compositing Homogenization October 2015 CFCC MSC

16 Equipment Decontamination For general grain-size and sediment identification samples: Site water rinse Simple scrub with a brush For samples taken for chemical analysis (e.g., pollutant identification): Site water rinse Soap and water wash; scrub with brush Distilled or deionized water rinse Acetone or ethanol rinse Site water rinse ALWAYS document all decon methods October 2015 CFCC MSC

17 Preventing Contamination of Samples Selection of sampling equipment Selection of sample containers Maintaining a barrier between the sample/sampling gear and any other object: Wear gloves Have clean space for sample gear Do not set sample containers down until complete Teflon coatings Do not dump decon materials into sampling area Always sample from least contaminated areas to most contaminated areas within site October 2015 CFCC MSC

18 Sample Storage Storage conditions should be achieved as quickly as possible and in appropriate, labeled containers Preservation: Refrigeration Ice-chest or insulated container containing ice or ice packs Refrigerator Freezing Dry ice Freezer Preservative Reagents Not typically used in sediment samples October 2015 CFCC MSC

19 Sample Transport Tailored to each study Transport may be: From study site directly to analysis lab, or From study site to local storage facility; followed by transport to analysis lab by freight carrier MUST: Maintain sample temperature Exclude light Secure samples to prevent mixing of sediment Chain of custody form may be necessary October 2015 CFCC MSC

20 EPA Recommendations October 2015 CFCC MSC

21 EPA Recommendations October 2015 CFCC MSC

22 EPA Recommendations October 2015 CFCC MSC

23 References Lecture Content US Environmental Protection Agency (EPA) Office of Water. (2001) Methods for Collection, Storage, and Manipulation of Sediments for Chemical and Toxicological Analyses: Technical Manual. EPA-823-B October Hazardous Materials Training and Research Institute (HMTRI) Writing Team. (2002). Preserving the Legacy: Site Characterization, Sampling and Analysis. In Chapter 3 Equipment and Sample Preparation and Chapter 5 Sampling Soils and Sediments (pp , ). Hoboken, NJ: John Wiley & Sons, Inc. Images Slides 7 & 11: Grabs and Corers - Slide 9: Grab Sample Slide 14: Subsampling & Compositing Slide 18: Delivery truck Slides 19, 20, & 21: EPA recommendations October 2015 CFCC MSC