Using sediment cores: Case studies to assess contamination in estuarine

environments

Brad HubenySalem State University

Introduction

• Salem State is adjacent to an estuary that has experienced various human impacts since the early 17th century

• Goal of this project is to allow students to investigate how human activities can be preserved in the sedimentary record

• In-class and take-home assignment

Audience

• Sophomore/Junior level Geology elective: Estuaries and Pollution

• ~25% are non-geology majors who have taken at least Physical Geology and have an interest in environmental science

• Most students are from the region, so Salem Sound has a personal connection to them

Objectives• Investigate the concept of sediment proxy data

to reconstruct environmental conditions from the past

• Quantitatively relate sediment depth to age of deposition

• Assess a contaminant’s level of impact using sediment quality guidelines

• Practice formulating and testing scientific hypotheses

• Final Report: Standard written format with associated figures

Data Sources

• Three sediment cores with age constraints and organic matter concentration; one core with CNS isotope, magnetics, and metals data

• Two undergraduate theses, which were both presented at NEGSA in 2011 – Ellen Kristiansen– Andrew Danikas

• More recent analyses associated with a manuscript in prep.

Salem Sound

Sediment Cores

Step 1: Hypothesis Formulation: How might documented population growth

show up in the sediment record?

Additional Watershed Information:•Peabody was “Leather Capital of the World” from 19th century until mid-20th century•Effluent pipe discharged raw sewage to estuary from 1905-1977•Primary sewage treatment started in 1977•Secondary sewage treatment started in 1998

US Census Data

Step 2: Computing Age from Depth

Mid Depth (cm) Age 14C calibration error Be-7 (mBq/g) Error (+/-) Cs-137 (mBq/g) Error (+/-)0.75 2007 10.61 2.08 1.01 0.122.25 2000 0 0 1.63 0.313.75 1993 1.51 0.195.25 1986 1.95 0.26.75 1980 2.19 0.238.25 1973 0.93 0.359.75 1966 0.37 0.32

11.25 1960 0 012.75 195314.25 194615.75 193918.75 192621.75 191324.75 189927.75 1886

74 1606 81

Step 2: Computing Age from Depth

Step 3a: Test organic matter hypothesisBasic time series

How well do they match? Is something else going on?

Step 3b: Test organic matter hypothesisSpatial Distribution

Step 3c: Test organic matter hypothesis

More advanced with CN data

Step 4a: Test Contaminant Hypothesis

Step 4b: How “bad” are these levels?

ERL & ERM fromLong et al, 1995

ERM: 370ppm

ERM: 218ppm

ERM: 410ppm

ERL: 150ppm

ERL: 34ppm

Acknowledgments

• Ellen Kristiansen, Andrew Danikas, Jeremy Louisos, Bridgette Gillespie, John Strom, Jess Jones, Joe Incatasciato

• Curtis Olsen and Jun Zhu, UMass Boston• Doug Allen, William Hamilton, SSU• SSU Dean of the College of Arts and Sciences

• Massachusetts Bays Program• Massachusetts Environmental Trust• National Science Foundation• Barbara Warren and Salem Sound Coastwatch