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MAJOR FINDINGS
![Figure 5. Stream conditions for fish communities have improved from the 1970s to the 1990s at 41 of 88 sites in northern New Jersey.](images/linj_fig005.gif) |
Figure 5. Stream conditions for fish communities
have improved from the 1970s to the 1990s at 41 of 88 sites in northern
New Jersey. |
Stream Conditions for Fish Have
Improved Since the 1970s
Fish are useful indicators of environmental changes
in drainage basins because they are sensitive to a wide variety of stresses
including changes in water chemistry and flow, modifications in habitat
and food, and landscape alterations resulting from urbanization and other
human-related activities. Moreover, fish accumulate certain contaminants
within their tissues over their entire life span (Fausch and others, 1990;
Karr and others, 1987, Chang and others, 2000). One way to identify environmental
changes in watersheds is to assess changes in stream condition by use
of an Index of Biotic Integrity (IBI; blue text box below). On the
basis of IBI results, conditions for fish in streams of the Delaware,
Passaic, and Raritan River Basins have improved since the 1970s (fig.
5; table 2) (Chang and others, 2000).
Of the 88 sites assessed, stream condition improved
at 46 percent, worsened at only 13 percent, and remained the same at 41
percent from the 1970s to the 1990s (fig. 5).
Many factors, especially the improved treatment of
wastewater discharges during the 1980s and changes in land-use practices,
may have contributed to the statistically significant increase in IBI
scores in all three basins (table 2). Nonpoint sources were less of
a factor than were point-source improvements; but as discussed on pages
7 and 8, urban nonpoint influences are still significant. The Delaware
River Basin reflected the greatest improvement in stream condition, moving
from a condition category of fair up to good (table 2).
A change in stream condition also can be assessed by
comparing the percentage composition of the fish families (fig. 6). For
example, the highly contaminant-tolerant white suckers made up a greater
percentage of the fish communities in all basins during the 1970s than
in the 1990s, especially in streams in the Delaware River Basin. In addition,
during the 1990s, darters, of which many species (for example, the shield
darter) are highly intolerant of human disturbance and habitat modification,
increased in abundance in streams in the Passaic and Raritan River Basins
and remained unchanged in streams in the Delaware River Basin.
Many minnow species are indicators of good stream condition
because they rely directly on the availability of aquatic insects for
survival. Thus, as streams become degraded and insects and their larvae
become scarcer, the numbers of insect-eating minnows often decrease. Minnows
made up greater than 42 percent of the community during the 1970s
and 1990s in all three river basins (fig. 6). The percentage of minnows
increased in Delaware River streams. Minnows decreased slightly in the
Passaic and Raritan River streams, however, an indication that these two
basins may still reflect some degree of impairment.
Table 2. The mean Index of
Biotic Integrity (IBI) scores for streams of the Delaware, Passaic,
and Raritan River Basins have increased significantly from the
1970s to the 1990s. [n, the number of stream sites assessed; *
indicates a significant change in mean IBI score (Chang and others,
2000)]
|
Index |
Delaware River
(n=32) |
Passaic River
(n=24) |
Raritan River
(n=32) |
Mean
Index of Biotic Integrity score |
|
|
|
Condition
rating |
|
|
|
Index of Biotic Integrity (IBI)—Ten community
measures (often called biometrics) based on the number of fish species,
feeding habits, abundance, and health are used to evaluate the biological
integrity of streams. A score of 1, 3, or 5 is assigned to each community
measure on the basis of overall similarity to an appropriate regional
reference site, 5 indicating most similar and 1 indicating least similar
to reference conditions. Scores for individual community measures
at each sampling location are then summed to produce a total score,
which is assigned a condition category. The maximum score a site can
receive is 50 and the minimum is 10. The four condition categories
are excellent (44–50), good (37–43), fair (29–36), and poor (10-28)
(Kurtenbach, 1993). The IBI serves as an integrated analysis because
individual biological measures provide differing levels of sensitivity
to changes in biological condition (Barbour and others, 1999). |
These differences, perhaps, may explain why the mean
IBI score for streams in the Delaware River Basin increased slightly more
than that for streams in the Passaic or Raritan River Basins (table 2).
Other fishes (such as eels) were not included in this comparison because
they are found over a large range in water-quality and habitat conditions,
thus limiting their use as aquatic indicators (Kurtenbach, 1993). Chang
and others (2000) provide information on collection methods, fish taxonomy,
and variability between the 1970s and 1990s collections.
|
Figure 6. Changes in the percentage of fish
families (that is, a decrease in suckers and a general increase in
darters) captured in streams of the Delaware, Passaic, and Raritan
River Basins during the 1970s (top) and the 1990s (bottom) indicate
that stream conditions have improved. |
Aquatic
Invertebrate Communities Differ Naturally Across the Study Area
The New Jersey Department of Environmental Protection
(1994b) established 43 reference or benchmark sites whose drainage basins
have been minimally disturbed by human activity. A comparison of these
sites indicates that the aquatic invertebrate communities in the southern
New Jersey Coastal Plain are distinctly different from those in the north
as a consequence of natural differences in environmental and physical
conditions (table 3). Thus, natural variability in aquatic invertebrates
needs to be taken into account when assessing communities across the entire
study area. This finding helped focus our data-collection efforts toward
gaining a better understanding of urban influences on northern New Jersey
communities. In addition, analysis of LINJ NAWQA data indicates that aquatic-invertebrate
communities on Long Island closely resemble New Jersey Coastal Plain communities
because of similar physiographic and habitat conditions.
Table 3. Differences in aquatic-invertebrate
communities in reference streams between northern and southern
(Coastal Plain) New Jersey can be explained by natural differences
in environmental conditions
|
|
Northern
New Jersey |
Southern
New Jersey |
Most abundant aquatic
invertebrates |
Mayflies, stoneflies,
caddisflies, and riffle beetles |
Worms, freshwater
clams, black flies, midges, caddisflies, and stoneflies |
Environmental characteristics |
Steeper channels
and higher dissolved oxygen content |
Low pH and low dissolved
solids and nutrient content |
Streambed
characteristics |
Mainly rock and cobble |
Mainly sand and other
fine sediments |
Fish and Aquatic Invertebrate
Communities Are Impaired in Urban Areas
![Figure 7. Aquatic-invertebrate-community data at more than 700 New Jersey AMNET sites (blue text box above) commonly indicate moderate to severe impairment in higher density urban areas (gray areas in fig. 1, p. 3).](images/linj_fig007.gif) |
Figure 7. Aquatic-invertebrate-community
data at more than 700 New Jersey AMNET sites (blue text box above)
commonly indicate moderate to severe impairment in higher density
urban areas (gray areas in fig. 1, p. 3). |
Despite some overall improvements in stream condition
(p. 5), fish and aquatic-invertebrate communities
are commonly impaired in the urbanized parts of New Jersey (figs.
7 and 8; see also fig. 1 on p.
3 for a comparison with urban area). Community-impairment scores at
more than 150 fish-sampling sites (Kurtenbach, 1993) and more than 700
aquatic-invertebrate sampling sites (for example, New Jersey Department
of Environmental Protection, 1994a) in New Jersey were examined with respect
to land use and other basin characteristics. The northwestern part of
the State is less developed and consequently was least likely to reflect
moderately or severely impaired aquatic communities (figs. 7 and 8).
The percentage of urban area in the drainage basin
and the amount of treated wastewater flows upstream from sampling sites
were the primary factors related to a severely impaired aquatic-invertebrate
community (Kennen, 1999). Total amount of forest land in the basin,
however, was a strong mitigating factor and increased the likelihood of
an unimpaired aquatic-invertebrate community. Similarly, total population
in proximity to the sampling site and the amount of urban land in a basin
were found to be most highly related to poor fish-community conditions.
![Figure 8. Fish-community data at more than 150 sampling sites in northern New Jersey indicate that streams in urban areas are in poor to fair condition (based on IBI scores; blue text box on p. 5).](images/linj_fig008.gif) |
Figure 8. Fish-community
data at more than 150 sampling sites in northern New Jersey indicate
that streams in urban areas are in poor to fair condition (based on
IBI scores; blue text box on p. 5). |
New Jersey Department of Environmental Protection’s
Ambient Biomonitoring Network (AMNET) is a statewide network of
more than 700 aquatic-invertebrate sampling sites that was designed
to monitor the condition of aquatic-invertebrate communities in five
water-management areas on a 5-year rotational basis. This sampling
frequency is considered to be realistic for evaluating long-term environmental
changes. Sampling locations (fig. 7), which were chosen in a stratified-random
design to monitor all nontidal streams at approximately 3-mile intervals,
include 43 reference sites. In addition, this network was designed
to incorporate, wherever possible, existing USGS and NJDEP cooperative
water-quality monitoring stations to maximize the integration of water-quality
and biological information. Level of community impairment (non-impaired,
moderately impaired, and severely impaired) is based on a modification
of the USEPA Rapid Bioassessment Protocol II (Plafkin and others,
1989). |
The following section describes an extension of these
analyses of available data through an integrated study of the specific
factors that affect biological communities in urban environments.
Characteristics of
Urban Landscapes That Affect Aquatic Communities
More than 400 landscape and environmental variables
were aggregated for comparison with data describing fish, invertebrate,
and algal communities at 36 streams in New Jersey and Long Island. Sites
were chosen with drainage basins that ranged from 3 to 96 percent urban
land. Analyses of these data indicated that increasing impairment of fish,
aquatic-invertebrate, and algal communities was statistically related
to components of the urban gradient (table 4; refer
also to “Glossary,” p. 31).
Table 4. Environmental factors
that were highly related to impairment of fish, aquatic-invertebrate,
and algal communities along an urban land-use gradient. Green
shading indicates factors that were more favorable to healthy
aquatic communities and red shading indicates factors that were
less favorable. [NS, No statistically significant effect on aquatic
community]
|
|
Response of aquatic community |
Watershed characteristic |
Fish |
Aquatic invertebrates |
Algae |
Area of forest and
wetlands |
NS |
Positive |
NS |
Ability to maintain
base flow |
NS |
Positive |
NS |
Percentage of cobble
substrate |
Positive |
Positive |
NS |
Median sulfate concentration |
NS |
Positive |
Positive |
Median total phosphorus
concentration |
Negative |
NS |
Positive |
Mean annual flood |
Negative |
Negative |
Negative |
Flashiness of streamflow |
Negative |
NS |
NS |
Impervious area, road
area only |
Negative |
Negative |
Negative |
Impervious area, nonroad
area only |
NS |
Negative |
NS |
Population density |
Negative |
Negative |
Negative |
Total urban area in
1986 |
Negative |
NS |
NS |
Urban area growth from
1986 to 1995 |
NS |
Negative |
NS |
Commercial and industrial
area in 1986 |
NS |
Negative |
Negative |
Total point-source
flow |
NS |
Negative |
NS |
Environmental factors such as annual peak discharge,
amount of impervious road area, and population density were related to
impairment in all three types of aquatic communities (negative in
table 4). Some environmental factors such as point-source flow, urban
growth during 1986–95, and impervious nonroad area were related to impairment
in the aquatic-invertebrate community only (negative in table 4). In addition,
total urban area in 1986 appeared to be important only for the fish community.
Other studies have found that historical changes in land use may have
significant implications for longer-lived organisms such as fish.
![Figure 9. Unregulated impervious-area runoff directly affects water quality, habitat, and aquatic communities in streams and is exemplified by a stormsewer pipe (left) that drains directly into the Saddle River at Ridgewood, N.J.](images/linj_fig009.gif) |
Figure 9. Unregulated impervious-area runoff
directly affects water quality, habitat, and aquatic communities in
streams and is exemplified by a storm-sewer pipe (left) that drains
directly into the Saddle River at Ridgewood, N.J. |
The presence of cobble substrate was a factor contributing
to healthier fish and aquatic-invertebrate communities (positive in table
4). Degradation of cobble and other stream habitat in urban systems likely
is related to increases in flow, channel erosion, and sedimentation common
to minimally controlled urban stormwater runoff (fig. 9).
In fact, changes in hydrologic factors (such as decreases
in base flow and increases in peak discharge and the flashiness of streamflow)
play a major role in influencing the types and condition of aquatic communities
present in a stream (table 4, fig. 10), in large part, by the way
these changes in flow affect stream habitat. As a result, stream communities
are continually stressed and rarely reach stable population levels in
urban systems. Conversely, reductions in base flow resulting from changes
in water-use and wastewater distribution practices greatly influence the
suitability of a stream for many types of organisms (Klein 1979). The
area of forest and wetlands in the drainage basin was a positive factor
in the health of aquatic-invertebrate communities (tables 4 and 5). Forests
and wetlands play a major role in maintaining a healthy supply of water,
food, and habitat for disturbance-intolerant and highly desired species.
Thus, forest and wetlands are able to help mitigate the undesirable effects
of other human-induced landscape alterations.
Figure 10. Reductions
in base flow of streams resulting from changes in up stream land-use
and water-use practices affect the distribution of aquatic species
in streams. For example, the difference in wetted habitat for median-flow
conditions (upper photograph) and low-flow conditions (bottom photograph)
at Neshanic River at Reaville, N.J., is substantial, although not
entirely related to human activities. |
![Figure 10. Reductions in base flow of streams resulting from changes in up stream land-use and water-use practices affect the distribution of aquatic species in streams. For example, the difference in wetted habitat for median-flow conditions (upper photograph) and low-flow conditions (bottom photograph) at Neshanic River at Reaville, N.J., is substantial, although not entirely related to human activities.](images/linj_fig010b.gif) |
![Figure 10. Reductions in base flow of streams resulting from changes in up stream land-use and water-use practices affect the distribution of aquatic species in streams. For example, the difference in wetted habitat for median-flow conditions (upper photograph) and low-flow conditions (bottom photograph) at Neshanic River at Reaville, N.J., is substantial, although not entirely related to human activities.](images/linj_fig010a.gif) |
Organochlorine
Compounds Were Detected in Streambed Sediment and in Fish Tissue
Even though the use of many organochlorine compounds
has been discontinued, the widespread historical application and the environmental
persistence of compounds such as chlordane, dieldrin, DDT, and PCBs have
led to frequent detection in streambed sediment and in whole-fish tissue
samples in Long Island and New Jersey (Stackelberg, 1997; Long and others,
2000). Analyses of available bed-sediment chemical data for nearly 300
sites (Stackelberg, 1997) indicate that chlordane and dieldrin concentrations
in bed sediments were highest in urban areas, reflecting their past use
for termite control. Concentrations of DDT and PCBs were highest in urban
and industrial areas, reflecting their principal historical use as an
insecticide and an industrial chemical (in hydraulic lubricants and heat-resistant
oils in electrical transformers), respectively. No significant relations
were found, however, between chlorinated hydrocarbon concentrations in
bed-sediment and whole-fish samples (white sucker, the chosen target species
for this analysis) or between those in whole-fish samples and land use
(Long and others, 2000).
Table 5. Comparison of biological
status at 36 Long Island–New Jersey stream sites to 140 NAWQA sites
nationwide indicates that the high scores relative to other NAWQA
sites are associated with urban watersheds. Sites are ordered from
top to bottom in descending percentage of urban land (urban gradient) |
![Table 5. Comparison of biological status at 36 Long IslandNew Jersey stream sites to 140 NAWQA sites nationwide indicates that the high scores relative to other NAWQA sites are associated with urban watersheds. Sites are ordered from top to bottom in descending percentage of urban land (urban gradient)](images/linj_table005.gif) |
Organochlorine pesticides in
the environment—Following discovery of the tremendous insecticidal
properties of DDT in the 1940s, numerous organochlorine insecticides
(for example, dieldrin, chlordane, heptachlor, and DDT) were developed
and used extensively for the control of agricultural pests as well
as termites in residential and commercial settings. DDT was also used
historically to control mosquito and gypsy moth populations in residential
and forested areas. The use of these insecticides peaked in the 1960s,
but because of concerns over their toxic effects and tendency to bioaccumulate,
restrictions on their use began in the 1970s; all uses of these organochlorine
insecticides were discontinued by the mid-1980s. The residues of organochlorine
insecticides are, however, extremely persistent in the environment.
Once introduced into the aquatic environment, the lipophilic (“fat-loving”)
nature of these compounds allows them to bioaccumulate and ascend
through the food chain, often resulting in adverse effects on many
aquatic species and fish-eating birds and wildlife. |
Of the eight streams sampled in fall 1997, one-half
of all bed-sediment samples contained concentrations of chlordane, DDT,
and PCBs that exceeded threshold effect levels (fig. 11; blue
text box on p. 12; Long and others, 2000). Concentrations of chlordane
and PCBs in whole-fish samples from many of the sites exceeded established
guidelines for fish-eating wildlife. Some of the detected compounds are
known to pose human health risks; however, concentrations in whole-fish
samples from this study are not directly comparable to concentrations
in edible portions (fillets) that are used to establish U.S. Food and
Drug Administration (FDA) action levels for human consumption (U.S. Food
and Drug Administration, 1992). Nonetheless, the FDA action levels for
human consumption of total chlordane [300 µg/kg (micrograms per kilogram)],
total DDT (5,000 µg/kg), and total PCBs (2,000 µg/kg) in edible portions
of fish were not exceeded in the whole-body samples at any of the sites.
Organochlorine compounds in lake-sediment cores and in water samples are
discussed on pages 14 and 20, respectively.
![Banner: Aquatic-Community Status in a National Context.](images/linj_banner_aquatic.gif)
Comparisons of invertebrate and algal status at 36 LINJ sites to
their status at 140 selected NAWQA sites nationwide were made using
nationally derived indicators (described in blue text box below).
These indicators were selected because of their ability to discriminate,
in a predictable way, human influences on the environment. These
indicators also have the desirable characteristic of sensitivity
to environmental stressors and a low dependency on natural variability
such as elevation, stream size, and ecoregion. The results discussed
in this section are for the sole purpose of a national comparison
and refer only to a population of NAWQA Program sampling sites.
They are not designed to be used as benchmarks for other State,
regional or national studies because the aquatic community indicators
have not been calibrated for such purposes.
Biological indicators
of water quality in a national context—The selected biological
indicators respond to changes in stream degradation. Degradation
can result from a variety of factors that modify habitat or
other environmental features such as land use, water chemistry,
and streamflow. Algal status focuses on changes in the
percentage of certain algae in response to increasing siltation
and often appears to correlate closely with increasing nutrient
concentrations. Invertebrate status is the average of
11 invertebrate biometrics that summarize changes in richness,
tolerance, trophic conditions, and dominance associated with
water-quality degradation. Fish status, which sums the
scores of four fish metrics (percent tolerant, omnivorous, non-native
individuals, and percent individuals with external anomalies),
was not used for this national comparison because values for
the full suite of sites were not available. For all these indicators,
higher values indicate a more degraded system. |
About one-half of LINJ status scores ranked
in the middle one-third (yellow squares, table 5) of the 140 NAWQA
sites sampled during 1996–98. Some LINJ status scores (orange squares),
however, were in the upper one-third, and a few sampling sites such
as the Elizabeth River at Hillside, Rahway River at Washington Park,
and Passaic River near Chatham, N.J., were among the highest scores
nationally for algae and invertebrates. All these sites fell in
the upper part of the urban gradient, or in basins with greater
than 47 percent urban land use. These sites were dominated by disturbance-tolerant
aquatic invertebrates such as worms and midges and supported few
if any disturbance-sensitive invertebrates such as mayflies, stoneflies,
and caddisflies. In addition, highly silt-tolerant algae made up
from 86 to 98 percent of the overall community abundance. The presence
of these tolerant forms reflect significant levels of disturbance
and highly degraded instream and riparian habitat.
About 35 percent of the LINJ status scores
were among the lowest one-third nationally (blue squares, table
5). The Rockaway River at Boonton (figure top right), Lamington
River near Pottersville, South Branch Raritan River at Arch Street,
Spruce Run at Glen Gardner, Pequannock River at Riverdale, and Flat
Brook near Flatbrookville, N.J., had some of the lowest scores nationally
for algae and invertebrates (table 5). Land use in the basins of
these sites is less than 34 percent urban. These sites were among
the most diverse sampled in the LINJ study; 50 to 79 percent of
the invertebrate community was composed of intolerant organisms
such as mayflies, stoneflies, and caddisflies. In addition, silt-tolerant
algae made up less than 19 percent of the algal community abundance
at all sites.
![Sampling aquatic invertebrates in the Rockaway River at Boonton, N.J.](images/linj_photo01.gif) |
Sampling aquatic invertebrates in the Rockaway
River at Boonton, N.J. |
Two sites, Beden Brook near Rocky Hill and Doctors Creek at Allentown,
N.J., were among the sites with the highest status scores nationally
(most degraded) for algae and invertebrates, respectively (table
5), yet corresponding basins had relatively little urban land (less
than 25 percent). In addition to nonpoint-source influence, these
sites likely reflect additional degradation resulting from wastewater-treatment-plant
effluent. Doctors Creek also has a high proportion of agricultural
land and far less forest than many of the sites on the lower end
of the urban gradient. Agricultural land is known to produce high
levels of sedimentation in surface water and high levels of nutrients
in surface water and ground water (see section on nitrate concentrations,
p. 15), which have historically been linked to aquatic-community
degradation (Culp and others, 1986). |
Trace-Element Concentrations
Were Elevated in Streambed Sediment, Fish Tissue, and Ground Water
Human activities have accelerated the release of trace
elements to aquatic environments through point- and nonpoint-source contamination
(blue text box below). Analyses of available bed-sediment chemical data
for nearly 300 sites (O'Brien, 1997) indicated that trace-element concentrations
in bed sediments were generally higher in the northern New Jersey physiographic
provinces (related to urban development and geologic availability) and
lower in the Coastal Plain (related to lower organic content of sediments,
geologic availability, and stream-water pH). Higher copper, lead, and
zinc concentrations were correlated with increased population density;
zinc was correlated with wastewater-treatment-plant flows; higher arsenic
was correlated with increased agricultural land use; and higher chromium
was correlated with certain geologic deposits (especially in the New England
Physiographic Province).
All eight of the streams sampled during fall 1997 were
found to have at least two trace elements that exceeded TELs in bed sediment
(fig. 11; Long and others, 2000; blue text box on TELs and PELs below).
Concentrations of eight trace elements at Rahway River near Springfield
(fig. 11) exceeded TELs; arsenic, cadmium, and copper also exceeded PELs.
Trace elements in the environment–Geologic
weathering accounts for natural releases of trace elements to aquatic
environments. Human activities, however, have accelerated the release
through point- and nonpoint-source contamination. Historically, industrial
and other point sources were significant, as were releases from fossil-fuel
burning and use of trace-element-based pesticides. More commonly now,
trace elements from atmospheric deposition, vehicular traffic, and
other activities accumulate on urban surfaces and are subsequently
carried in runoff to streams. When introduced into aquatic environments,
trace elements adsorb to fine-grained sediments (Forstner and Wittman,
1983). Trace elements can accumulate in sediments and may affect the
health of bottom-dwelling (benthic) organisms and higher trophic-level
species (fish) that rely on benthic organisms for food. Although some
trace elements such as copper, iron, manganese, selenium, and zinc
are vital to the metabolic processes of aquatic organisms, they can
still be toxic at high concentrations. |
![Figure 11. Concentrations of selected trace elements and organochlorine compounds in bed sediment commonly exceeded TEL and PEL guidelines, especially at urban sites. (Background concentrations were estimated using method of Velz (1984); see blue text box below concerning TELs and PELs.)](images/linj_fig011.gif) |
Figure 11. Concentrations of selected trace
elements and organochlorine compounds in bed sediment commonly exceeded
TEL and PEL guidelines, especially at urban sites. (Background concentrations
were estimated using method of Velz (1984); see blue text box below
concerning TELs and PELs.) |
Copper, manganese, mercury, and selenium were detected
in fish livers at all sites. No significant relations were found between
trace-element concentrations in fish livers and those in bed sediment
or between concentrations in fish livers and any land-use category or
population density (Long and others, 2000).
Arsenic was detected in 17 of
22 samples collected from domestic-supply (household) wells completed
in fractured bedrock aquifers of the Piedmont Physiographic Province,
where geologic formations are known to contain arsenic-bearing minerals.
Concentrations ranged from 1 to 57 µg/L. The current drinking-water standard
for arsenic is 50 µg/L, but the USEPA has proposed a tenfold decrease
in this standard to 5 µg/L. Six of the samples (27 percent) contained
arsenic in concentrations equal to or greater than 5 µg/L.
Concentrations of radium (sum
of Ra-226 and Ra-228) above the drinking-water standard were found in
33 percent of 170 wells sampled in the surficial aquifer system in southern
New Jersey (Szabo and others, 1997). The highest radium levels were in
areas where acidic waters are associated with surficial sediments that
contain radium from geologic sources (primarily the Bridgeton Formation)
and agricultural areas where use of nitrogen fertilizers and lime is heavy.
The leaching and nitrification of applied fertilizers, which increase
the dissolved-solids content and acidity of ground water, are likely mechanisms
by which radium is mobilized from surficial sediments and transported
to ground water. More recently, the short-lived isotope radium-224 was
detected in samples from this surficial aquifer system in waters affected
by the same chemical processes (Zoltan Szabo, U.S. Geological Survey,
written commun., 2000).
In a 59-well subset of the 170 wells above, mercury
was detected at concentrations above the drinking-water standard of 2
µg/L in about 10 percent of the samples. The source is suspected to be
linked to past use of mercury-based pesticides. Mercury may have increased
mobility as a result of the natural acidity of waters from the surficial
aquifer in southern New Jersey, as well as widespread contamination of
these waters with chloride from road salt, septic systems, and other discharges;
but the mechanisms are as yet not well understood.
TELs and PELs—Currently,
there are no U.S. standards for assessing the potential for adverse
biological effects due to contaminated freshwater sediment. The Canadian
Council of Ministers of the Environment (CCME) modified an approach
by Long and Morgan (1991) to develop guidelines for marine and freshwater
sediments. The CCME modified approach uses two assessment levels:
(1) the threshold effect level (TEL), representing the concentration
below which adverse effects are expected to occur rarely, and (2)
the probable effect level (PEL), representing the concentration above
which adverse effects are expected to occur frequently (Ecosystem
Conservation Directorate Evaluation and Interpretation Branch, 1995).
Concentrations between TEL’s and PEL’s are values at which occasional
adverse biological effects are expected. Adverse biological effects
are generally defined as effects that are considered to produce a
negative response in an organism (for example, death, reduction in
growth, or reduced reproductive success). |
![Banner: Mercury Concentrations in Fish Tissue Were Related to Methylmercury Concentrations in Water](images/linj_banner_mercury.gif)
During summer 1998, the LINJ study participated with 20 other NAWQA
studies in a national survey (Krabbenhoft and others, 1999) in which
bed sediment samples were analyzed for total mercury and methylmercury,
and fish-muscle tissues (fillets) were analyzed for total mercury
(assumed to be predominantly methylmercury). Four sites were sampled
in the LINJ study area (map on p. 28).
Atmospheric deposition is the primary source of mercury to most aquatic
ecosystems in the eastern United States; in some areas, however, urban,
industrial, mining, volcanic, and (or) geothermal sources contribute
to elevated concentrations of total mercury in bed sediment. In addition,
past use of mercury-based pesticides on golf courses and certain agricultural
crops are possible sources.
Mercury is readily methylated in the natural environment as a result
of bacterially mediated sulfate reduction. Methylmercury is readily
bioaccumulated and biomagnified, is the primary form of mercury in
fish, and is a potent neurotoxin to humans and wildlife (fish, birds,
and mammals).
At the LINJ sites, mercury concentrations in fish tissue
(pickerel fillets) normalized by mean weight were positively related
to methylmercury concentrations in water and negatively related to
total mercury concentrations in bed sediment. These data indicate
that mercury concentrations in fish tissue are more a function of
methylmercury levels in water than in the sediment. This is consistent
with results found nationally in fish tissue (Dennis Wentz, U.S. Geological
Survey, written commun., 2000). The highest concentrations of mercury
in fish tissue [near 0.5 µg/g (micrograms per gram) wet weight] were
from the mixed-land-use site (Great Egg Harbor River), where relatively
high percentages of wetlands may enhance methylation rates. Concentrations
of mercury in fish tissue were intermediate in urban basins and lowest
in the agricultural basin.
Nationally, background and mixed (agricultural and forested) basins
had the highest mean mercury methylation efficiencies (as measured
by the ratio of methyl-mercury to total mercury) in water. Mixed (agricultural
and forested) basins had the highest mean methylation efficiencies
in bed sediment; methylation efficiencies in background, agricultural,
and urban basins were lower. |
![Banner: History of Chemical Use Is Evident in Lake-Sediment Cores](images/linj_banner_history.gif)
Analyses of lake sediment
cores are an effective method for evaluating water-quality trends.
(See blue text box below.) Cores were extracted from three lakes
in northern New Jersey and one on Long Island as part of a national
lake-coring study (Callender and Van Metre, 1997). Sediment
was dated by use of cesium-137, a by-product of nuclear-weapons
testing. Trace elements (arsenic, cadmium, chromium,
lead, mercury, nickel, and zinc) were detected throughout the
cores of all four lakes, with concentrations of most elements
elevated in the three urbanized basins relative to the largely
forested Clyde Potts Reservoir basin. Until concentrations
of lead peaked in the 1970s, lead and zinc concentrations were
highly correlated over time with the population in the vicinity
of the lake. Population is an indicator of vehicular traffic,
which in turn is an indicator of gasoline use (a probable lead
source) and tire wear (a probable zinc source). Removal of lead
from gasoline by the Clean Air Act resulted in a general decrease
in sedimentary concentrations of lead since the mid-1970s phaseout
(fig. 12); however, lead concentrations remain elevated compared
to detections at the base of the cores. Zinc concentrations
are generally increasing in the three urban watersheds in response
to increasing population and traffic density, but not in Clyde
Potts Reservoir, which is least affected by traffic.
Detectable concentrations of chlordane, total DDT, total polycyclic
aromatic hydrocarbons (PAHs) and total PCBs were found in all
lake cores; dieldrin was detected in only two lake cores. Generally,
concentrations of organochlorine compounds began to decline
after regulatory action discontinued organochlorine production
and use in the 1970s and 1980s, but the persistence of these
compounds may mean that a substantial amount of time must pass
before they are purged from the basin. Concentrations of PAHs,
however, are elevated and generally increasing over time in
sediment cores (fig. 13), presumably as a result of increased
vehicular and other fossil-fuel use associated with urban development.
Concentrations of PAHs were lowest in Clyde Potts Reservoir
(least traffic influence). Of particular note are the low concentrations
of PAHs in Packanack Lake sediments in the 1930s, when automobiles
were comparatively rare and before the watershed was urbanized.
These trends have been observed in other urban lake-sediment
cores across the United States (Callender and Rice, 2000). |
|
Figure 12. The mid-1970s phaseout
of lead from gasoline as a result of the Clean Air Act
has resulted in decreased basin inputs of lead concentrations
in lake sediment. |
|
Figure 13. Concentrations of total
polycyclic aromatic hydrocarbons (PAHs) are elevated and
generally increasing in sediment cores as a result of
increased vehicular traffic and fossil-fuel use. |
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Lake-sediment cores were useful
for discerning chemical-use history—Lakes are more representative
of a stable depositional environment than streams. Differences in
sediment concentrations between the lake-sediment cores are related
to differences in sedimentation rates and to factors affecting chemical
inputs such as population density, traffic density, chemical use,
and the extent of urban land use in the watershed. For example, even
though the concentrations are different, the reduction of contaminants
regulated by environmental legislation (chlordane, PCBs, DDT, and
lead) is clearly evident in the sedimentary record for the three urban
lakes. Bed-sediment chemical data from streams, although useful
for determining the relative effects of basin land use, had large
within-site sample variability and were not particularly useful for
trend detection, even with 25 years of data (Stackelberg, 1997;
O'Brien, 1997). This finding is typical of streambed-sediment data
because sediments of different ages and different sources are continuously
being mixed by changing hydrologic conditions. |
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|| Glossary
U.S. Geological Survey Circular
1201
Suggested citation:
Ayers, M.A., Kennen, J.G., and Stackelberg, P.E., 2000, Water Quality in the Long IslandNew Jersey Coastal Drainages New Jersey and New York, 199698: U.S. Geological Survey Circular 1201, 40 p., on-line at http://pubs.water.usgs.gov/circ1201/
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