Introduction
In 2000 the
Stroud Center was awarded
a Safe
Drinking Water Act (SDWA) grant funded by the New
York State Department of Environmental Conservation and the
USEPA to conduct
a six-year study to monitor and evaluate water quality and sources
of pollution in the streams,
rivers, and reservoirs that provide New York City's (NYC) drinking
water. The NYC drinking water supply and infrastructure are monitored,
maintained, and improved by NYC's Department
of Environmental Protection. The SDWA is the main federal law
(administrated by the USEPA)
that ensures the quality of America's drinking water.
This monitoring
program involves analyzing specific physical, chemical, and biological
indicators to measure, quantify, and determine sources and impacts
of contaminants throughout these watersheds. The project was designed
to enhance on-going monitoring projects and to provide an additional
baseline of information useful in such aspects as measuring changes
in water quality in response to changes in land cover/use and
the implementation of best management practices (BMP) for mitigating
both point and non-point source pollution. The project focuses
on ecosystem impairment (e.g., differences in stream community
structure and stream/reservoir productivity, levels of nutrient
processing or sequestering) and contaminant sources (e.g., point
sources such as wastewater treatment plants and non-point sources
such as agricultural fields).
Principal
Objectives
- Measure
specific environmental variables that statistically relate aquatic
ecosystem structure and function to land use, BMP implementation,
and other watershed inputs or factors.
- Measure
chemical, physical, and biological factors that can be used
to evaluate or indicate the occurrence and/or source of selected
chemical and biological aquatic contaminants.
- Provide
a baseline data set of biological indicators and ecosystem-level
variables and for assessing water quality improvements and aquatic
ecosystem responses resulting from on-going and historical land
cover/use change, BMP implementation, restorations, and mitigations.
Project
design
The project
was designed as a six-year study (2000-2005) divided into two distinct
three-year phases (download the Phase
I Report, 6 MB). Sixty stream sampling stations distributed
among the major sub-basins of the principal
source watersheds (East of Hudson River, EOH, and West of Hudson
River, WOH) in Phase I. The 60
sampling stations were designated as either a “targeted”
(n=50) or “integrative” (n=10) sampling
site depending on the location in the watershed and type and intensity
of variables being measured. Targeted stations occurred throughout
the watersheds on streams of varying sizes. Integrative stations
occur sufficiently downstream to integrate the effects of land use
and other factors on a given project element or task under study
over a large portion of the watershed.
Site selection
criterion was to capture the range in land
covers/uses across geologic and soil characteristics of all
NYC source watersheds. Secondary site selection criteria included
ongoing or future BMP implementation, presence of U.S.
Geologic Survey (USGS) stream gaging stations, and the feasibility
of studying the various study components. Sampling stations on
eight reservoirs were also established in Phase I.
Phase II
(2003-2005) of the project established 48 new (differing from
Phase I) stream sites and four new reservoir sites. Twelve of
the Phase I stream sites and three existing reservoir sites were
retained to maintain continuity between phases and provide a measure
of inter-annual variability. Phase II work builds upon Phase I
results by sampling other important tributaries and focusing sampling
effort to refine any ambiguous results from the Phase I effort.
The project
is designed as a broad synoptic survey repeated annually, rather
than as a highly targeted, spatially narrow survey with a high
degree of repetition in each year of study. Sampling is conducted
primarily in the late spring, summer, and early fall; however,
winter sampling is conducted as part of one study task.
Project
Components
There are
eight project elements or tasks:
Nutrients
and Major Ions in Transport are monitored during
summer baseflow and during stormflows. Major ions include cations
(i.e., sodium, magnesium, calcium, and potassium), and anions
(i.e., sulfate, chloride). Nutrients include various forms of
nitrogen and phosphorus. pH, alkalinity, and conductivity are
also measured at the study sites.
Molecular
Tracers are a broad group of compounds present
in the aquatic environment that are unique to various contaminant
sources. The use of such tracers is an emerging technique that
qualitatively links the presence of a particular contaminant
in a stream or river to a specific source of that contamination
within the upstream watershed. Tracers are measured during summer
and winter baseflow and during stormflows and include: fragrances
found in domestic products (e.g., detergents) and caffeine,
which are used to indicate the presence of waste water treatment
plant (WWTP) or septic effluent; fecal steroids, which track
animal (farm or wildlife) and human contamination; and polycyclic
aromatic hydrocarbons (PAH), which target urban/suburban sources
of contamination.
Macroinvertebrate
Community Structure provides an integrated (over
time) measure of water quality conditions. Stream dwelling invertebrates
are collected at the 60 stream sites during spring baseflow.
Benthic macroinvertebrates, such as insects, worms, and molluscs,
provide an extended temporal perspective (relative to the molecular
tracer, major ions and nutrient sampling performed periodically)
because they have limited mobility and relatively long life
spans (e.g., a few months to a year or more for some insects
and molluscs). Macroinvertebrates have measurable responses
to a wide variety of environmental changes and stresses that
can be easily analyzed, and they are an important link in the
aquatic food web.
Organic
Particles (Suspended Solids) in Transport are indicative
of the ability of a stream ecosystem to process organic matter,
provide a link between the upstream generation and downstream
transfer of organic energy, and provide an estimate of the carbon
loading to downstream reservoirs. The concentration, size distribution,
and transport of organic particles under baseflow conditions
and, to estimate response of organic particle transport to runoff
events, during stormflow.
DOC
and BDOC Dynamics. Dissolved organic carbon (DOC)
is an indicator of organic loadings to streams, as well as terrestrial
processing (e.g., within the soil, forests, and wetlands) of
organic matter. In the absence of extensive wetlands, bogs,
or swamps, baseflow concentrations of DOC in undisturbed watersheds
generally range from approximately 1 to 3 mg carbon/L. Higher
concentrations suggest sources of organic pollution such as
point sources from sewage treatment plant discharges or non-point-source
runoff from urban or rural landscapes. The biodegradable DOC
fraction (BDOC) consists of organic molecules that heterotrophic
bacteria can utilize as a source of energy and carbon. Within
the context of drinking water quality, some subset of DOC constitutes
the precursors of disinfection byproducts, and the BDOC constitutes
the nutritional resources that can contribute to biological
regrowth within water distribution systems.
Nitrogen
(N), Phosphorous (P), and Dissolved Organic Carbon (DOC) Spiraling.
Phosphorus, nitrogen, and carbohydrates tend to be taken up
and recycled several times as they move downstream. This cycling
and the
simultaneous downstream transport are sometimes referred to
as "spiraling." The "spiraling length" represents
the distance over which the average nutrient atom travels as
it completes one cycle of utilization from a dissolved available
form, passes through one or more metabolic transformations and
is returned to a dissolved available form. Spiraling in the
stream ecosystem reflects the degree of metabolic activity within
the system, the ability of the system to retain nutrients, and
the relative utilization rates (hence degree of nutrient limitation)
among different nutrients. Spiraling length also describes the
scale on which upstream processes are linked to downstream processes.
Thus spiraling represents a fundamental measure of stream ecosystem
function. Ecosystem impairment is likely to increase spiraling
length (reduce the cycling intensity) through reduced uptake,
excessive loading, or decreased retentive ability of the ecosystem.
An exception to this rule would occur when the increased loading
of a single nutrient stimulates uptake of a second nutrient,
whose spiraling length would shorten. Spiraling lengths of nitrogen,
phosphorus and carbon (DOC) are estimated in the ten integrative
stream sites under baseflow conditions.
Net
Stream Metabolism. Stream metabolism is assessed
concurrently with spiraling work (Task 6) at 10 integrative
stream sites. Stream metabolism measurements provide data on
two fundamental ecosystem functions – primary productivity
and community respiration. Gross primary productivity (GPP)
is a measure of the rate of synthesis of plant (primarily algal)
biomass, and respiration is an index of the breakdown of reduced
chemical energy, including the metabolic costs of photosynthesis.
These functional attributes are expected to relate principally
to biomass of algae, heterotrophic microorganisms, and, to a
lesser extent, macroinvertebrates. The actual rates are also
influenced by environmental variables of light, temperature,
and dissolved and particulate nutrients. Changes in activity,
or in the balance of activity, over time would be an important
signal that watershed activities are affecting function in a
stream entering a reservoir, and would indicate a need for follow-up
work on upstream tributaries.
Reservoir
Primary Productivity. Measuring primary productivity
in reservoirs allows us to determine whether there is a link
between the reservoirs and the primary tributaries to these
reservoirs. If the major tributary to a reservoir contributes
the most nutrients to the reservoir, we would expect that reservoirs
would rank in the same order as tributaries with respect to
metabolic activity. If they do not rank similarly, and the pattern
was sustained over a period of years, we would infer that nutrients
from other sources – or reservoir morphology or other
physical characteristics – are more important regulators
of metabolic activity than nutrients from the primary tributary.
Just as for the influent streams, a change in activity over
time will suggest that watershed changes are affecting processes
in the system.
Laboratories
and Principal Investigators
Organic
Geochemistry -
Anthony K. Aufdenkampe, Ph.D.
Biogeochemistry
-
Louis A. Kaplan, Ph.D.
Entomology
-
John K. Jackson, Ph.D.
Ecosystems
-
J. Denis Newbold, Ph.D.
Microbiology
- Thomas
L. Bott, Ph.D.
Information
Services - Charles L.
Dow, Ph.D. (NY Project Manager)
New York
Project Coordinator - Dave
B. Arscott, Ph.D.
Project
Director - Bernard
W. Sweeney, Ph.D. (Stroud President and Director)
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