This study investigates the relationship between microbial biodiversity and sediment contamination in two ponds within the Muddy River system. Willow Pond downstream is known to be contaminated with oil, pesticides and heavy metals, while Ward's Pond upstream has little contamination. Sediment samples from both ponds will be analyzed chemically and microscopically to quantify contaminant levels and compare microbial populations. Previous studies have found microbial indicators can assess water quality and ecosystem health in a simple, inexpensive way. The researchers hypothesize microbial diversity will be lower in Willow Pond's more contaminated sediments.

1. Effects of Contamination in Muddy River Sediment on Microbial Diversity
Abstract
The Muddy River, part of the Emerald Necklace park system designed by Frederick Law
Olmsted, has been contaminated for many years with oil, pesticides, and heavy metals.
This study will investigate if there is a relationship between the benthic biodiversity and the
level of contamination. Willow Pond (contaminated) is about 400 yards downstream from
Ward’s Pond (not contaminated). Both ponds will be sampled in areas of similar habitat
and sediment type for comparison. Analytical techniques will include gas chromatography/
mass spectroscopy for analysis of polycyclic aromatic hydrocarbons (PAHs), and x-ray
fluorescence for analysis of heavy metals in order to quantify the contaminant level. To
complement the chemical analysis, a study of microbial diversity of the two sites will be
conducted using microscopy (100x) and image analysis (CMEIAS) to quantify the
characteristics of microbial populations.
Background
Over many years of exposure to pollution, the water quality of much of the Muddy River has
deteriorated to the extent that only a very few species of fish can exist in many portions of
the river. Pollutants have arisen from street run-off, and releases of oil, and illegal sewer
discharges to the storm water system. Deferred park maintenance and neglect has allowed
the dominance of invasive species and the erosion of the riverbank. The Muddy River
Restoration Project that is currently underway aims to improve the water quality through a
number of initiatives. While the total cost is expected to total more than $50 million dollars
over several years, sufficient funding has been secured from governmental and non-
governmental agencies, including the Town of Brookline, the City of Boston, the
Commonwealth of Massachusetts, the Federal Government, and local non-government
agencies such as the Emerald Necklace Conservancy.
The significance of this research is to find out if there is a correlation between bacterial
species and contamination levels in the Muddy River. I will investigate whether there is a
trend in bacterial species found in contaminated versus cleaner sediments. While
analyzing dissolved oxygen levels or other chemical levels can be a good indicator of
health of a river, another way is to look at different microorganisms species in the
sediments. Chemical indicators are a good way to understand the chemistry of a river, but
it does necessarily predict a vibrant ecosystem. Indicator species of river are a way to test
if the habitat will support a diversity of species, while a contaminated water source may
have almost no biodiversity. Instead of disturbing sediment in order to catch invertebrates,
such as water bugs, it is less disruptive to collect small samples of sediment in order to
study microorganisms. Since they are also living organisms and have preferred habitats,
they can be used to assess biodiversity of a river. Some species are sensitive to pollution
and they can be a good indicator of what the water and sediment composition is like and if
it is also safe for human consumption or recreational use.
The US Environmental Protection Agency’s Environmental Monitoring and Assessment
Program (EMAP) started microbial assessments in Oregon Rivers in 1996 to test if
microbes are a good for environmental indicators. There are many known microorganisms
that could be used to test the health of the river, and could offer a relatively simple and
inexpensive way to monitor ecosystem health. There are many microbial species in waters
and studying these different species can give scientists a clearer idea what kind of
ecosystems different bacteria prefer and how that preference is linked to contaminated or
uncontaminated water sources. After testing the rivers in Oregon for a year, scientists
were able to conclude that using microbial indicators for public health may be useful in
determining the health of a river. HPC (Heterotrophic Plate Counting) and E.coli
significantly correlated with most of the harmful chemicals that were sampled from the
different rivers. Because of this study, it is possible to determine the health of a river, from
the bacteriological communities living in water. We hope to extend that type of analysis to
two ponds which have very different levels of contamination, but are within close proximity.
Angeline Chen, Abigail Smith, Erika Yasamura, Dr. Michael Berger
Department of Chemistry and Physics and the Department of Biology, Simmons College, Boston, MA 02115
12th Annual
Undergraduate Symposium on
Sustainability and the Environment
Bridgewater State University
December 7, 2013
References
Penninton, A.T., Harding, A. K., Hendricks, C.W., Campbell, H.M.K. (2001)
“Evaluating microbial lndicators of Environmental Condition is Oregon Rivers.”
Environmental Management, 28(6), 833-41.
“Screening and Assessment of Contaminated Sediment”, New York State
Department of Environmental Conservation, January 24, 2013, Draft Version 4.0,
http://www.dec.ny.gov/docs/fish_marine_pdf/contamsedimentrev.pdf, accessed
December 3, 2013
Acknowledgements
The authors gratefully acknowledge the Simmons College Department of
Chemistry and Physics and the Thermo Fisher Corporation.
MICROBIAL ANALYSIS - CMEIAS (Center for Microbial Ecology Image Analysis
Software) will be used to quantify microbial biodiversity by quantifying bacteria of
different shapes without identifying the specific bacterial species. CMEIAS was created
as a way to strengthen quantitative microscopy-based approaches to understanding
microbial ecology.
Biodiversity Assessment
Of Willow and Ward Pond
Image Analysis Using CMEIAS
- Image Enhancement
- Relative Microbial Populations
Correlation with Chemical Data?
Surficial
Sediment
Contaminants
(by
XRF)
Ward's
Pond
Willow
Pond
Screening
Level
(ppm)
(ppm)
(ppm)
As
9
17
33
Pb
146
267
130
Cr
17
57
110
Cu
33
122
150
Zn
68
250
460
Sample Prep of microbes from Sediment
-Sample representative location
-Wash sediment
-Prepare slide
CHEMICAL ANALYSIS - Sediment samples are collected about one foot from
the surface using a scoop. The solids were air-dried slowly for a week at room
temperature (avoiding heat to minimize the degradation or loss of volatiles),
finely ground using a mortar and pestle, and finally sieved through a 120 mesh. A
Thermo Scientific Niton XL3t portable X-ray fluorescence analyzer was used to
analyze for metals. Polycyclic Aromatic Hydrocarbon (PAH) contaminants will be
extracted from the sediment through agitation for 15 minutes at room
temperature with a 50/50 mixture of hexane and methylene chloride. The extract
was analyzed with a Perkin Elmer Claris 500 GC/MS with splitless injection and
single ion monitoring (SIM), normally used for analyzing contaminants at trace
levels.
Analytical Methods
Surficial
PAH
Sediment
Contaminants
(by
GC/MS)
Ward's
Pond
Willow
Pond
Screening
Level
(ppm)
(ppm)
(ppm)
Naphthalene
ND
0.07
7.7
Acenaphthylene
0.004
0.20
9.0
Acenaphthene
0.002
0.55
9.8
Fluorene
ND
0.88
10.8
Phenanthrene
/
Anthracene
0.056
7.0
24.0
Fluoranthene
0.095
18.8
14.1
Pyrene
0.10
16.8
14.0
Benz(a)anthracene
/
Chrysene
0.027
9.88
33.6
Benzo(a)pyrene
Benzo(b)fluoranthene
0.11
54.1
38.8
Indeno(1,2,3-­‐c,d)pyrene
Benzo(g,h,i)perylene
0.036
24.1
44.2
Dibenzo(a,h)anthracene
0.036
7.14
22.4
Screening
Level
(ppm)
with
Sediment
at
2%
Total
Organic
Carbon
(TOC)
from
U.S.
EPA
2003)
Results
The results from the chemical analysis confirm past results that Willow Pond has considerably
more contamination than Ward’s Pond. The PAH results indicate a significant difference
between the ponds, that is consistent with their different history. While Willow Pond was
impacted by a petroleum release about 10 years ago, and receives street storm water from a
couple of drains, Ward’s Pond has had a clean history and receives no storm water. Indeed,
the concentrations of PAH contaminants in Willow Pond are more than 100x greater than in
Ward’s Pond. However, XRF analysis shows that both ponds have lead concentrations that
exceed published Sediment Screening Values.
A Sediment Screening Value is a conservative tool for making an initial assessment of the
potential risks to aquatic life associated with contaminated sediment. They are primarily useful
as the initial step in a multistep approach. Usually an initial assessment is followed up with
three different types of sediment evaluations to ascertain risk: contaminant concentrations,
sediment toxicity tests, and benthic community analyses. The microbial analysis, which is part
of this test, will address the health of the benthic community in the two ponds.