Current Issues
Bioaccumulation
This Executive Summary is reproduced from the EPA Guidance
Manual referred to by Don Cox below.
Executive Summary
Traditionally, concerns relative to the management of aquatic resources
in freshwater ecosystems have focused primarily on water quality. As
such, early aquatic resource management efforts were often directed
at assuring the potability of surface water or groundwater sources.
Subsequently, the scope of these management initiatives expanded to
include protection of instream (i.e., fish and aquatic life), agricultural,
industrial, and recreational water uses. While initiatives undertaken
in the past twenty years have unquestionably improved water quality
conditions, a growing body of evidence indicates that management efforts
directed solely at the attainment of surface water quality criteria
may not provide an adequate basis for protecting the designated uses
of aquatic ecosystems.
In recent years, concerns relative to the health and vitality of aquatic
ecosystems have begun to reemerge in North America. One of the principal
reasons for this is that many toxic and bioaccumulative chemicals
[such as metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinatedbiphenyls
(PCBs), chlorophenols, organochlorine pesticides (OC pesticides), and
polybrominated diphenyl ethers]; which are found in only trace amounts
in water, can accumulate to elevated levels in sediments. Some of these
pollutants, such as OC pesticides and PCBs, were released into the
environment long ago. The use of many of these substances has been
banned in North America for more than 30 years; nevertheless, these
chemicals continue to persist in the environment. Other contaminants
enter our waters every day, from industrial and municipal discharges,
urban and agricultural runoff, and atmospheric deposition from remote
sources. Due to their physical and chemical properties, many of these
substances tend to accumulate in sediments. In addition to providing
sinks for many chemicals, sediments can also serve as potential sources
of pollutants to the water column when conditions change in the receiving
water system (e.g., during periods of anoxia, after severe storms).
Information from a variety of sources indicates that sediments in
aquatic ecosystems throughout North America are contaminated by a wide
range of toxic and bioaccumulative substances, including metals, PAHs,
PCBs, OC pesticides, a variety of semi-volatile organic chemicals (SVOCs),
and polychlorinated dibenzo -p- dioxins and furans (PCDDs and
PCDFs). For example, contaminated sediments pose a major risk to the
beneficial uses of aquatic ecosystems throughout the Great Lakes basin,
including the 43 areas of concern (AOCs) identified by the International
Joint Commission. The imposition of fish consumption advisories has
adversely affected commercial, sport, and food fisheries in many areas.
In addition, degradation of the benthic community and other factors
have adversely affected fish and wildlife populations. Furthermore,
fish in many of these areas often have higher levels of tumors and
other abnormalities than fish from reference areas. Contaminated sediments
have also threatened the viability of many commercial ports through
the imposition of restrictions on dredging of navigational channels
and disposal of dredged materials. Overall, contaminated sediments
have been linked to 11 of the 14 beneficial use impairments that have
been documented at the Great Lakes AOCs. Such use impairments have
also been observed elsewhere in Canada and the United States.
In response to concerns raised regarding contaminated sediments, responsible
authorities throughout North America have launched programs to support
the assessment, management, and remediation of contaminated sediments.
The information generated under these programs provide important guidance
for designing and implementing investigations at sites with contaminated
sediments. In addition, guidance has been developed under various sediment-related
programs to support the collection and interpretation of sediment quality
data. While such guidance has unquestionably advanced the field of
sediment quality assessments, the users of the individual guidance
documents have expressed a need to consolidate this information into
an integrated ecosystem-based framework for assessing and managing
sediment quality in fresh water ecosystems (i.e., as specified under
the Great Lakes Water Quality Agreement). Practitioners in this field
have also indicated the need for additional guidance on the applications
of the various tools that support sediment quality assessments. Furthermore,
the need for additional guidance on the design of sediment quality
monitoring programs and on the interpretation of the resultant data
has been identified.
This guidance manual, which comprises a three-volume series and was
developed for the United States Environmental Protection Agency, British
Columbia Ministry of Water, Land and Air Protection, and Florida Department
of Environmental Protection, is not intended to supplant the existing
guidance on sediment quality assessment. Rather, this guidance manual
is intended to further support the design and implementation of assessments
of sediment quality conditions by:
- Presenting an ecosystem-based framework for assessing and managing
contaminated sediments (Volume I);
- Describing the recommended procedures for designing and implementing
sediment quality investigations (Volume II); and,
- Describing the recommended procedures for interpreting the results
of sediment quality investigations (Volume III).
The first volume of the guidance manual, An Ecosystem-Based
Framework for Assessing and Managing Contaminated Sediments in
the Freshwater Ecosystems, describes the five step process
that is recommended to support the assessment and management of
sediment quality conditions (i.e., relative to sediment-dwelling
organisms, aquatic-dependent wildlife, and human health). Importantly,
the document provides an overview of the framework for ecosystem-based
sediment quality assessment and management (Chapter 2). In addition,
the recommended procedures for identifying sediment quality issues
and concerns and compiling the existing knowledge base are described
(Chapter 3). Furthermore, the recommended procedures for establishing
ecosystem goals, ecosystem health objectives, and sediment management
objectives are presented (Chapter 4). Finally, methods for selecting
ecosystem health indicators, metrics, and targets for assessing
contaminated sediments are described (Chapter 5). Together, this
guidance is intended to support planning activities related to
contaminated sediment assessments, such that the resultant data
are likely to support sediment management decisions at the site
under investigation. More detailed information on these and other
topics related to the assessment and management of contaminated
sediments can be found in the publications that are listed in the
Bibliography of Relevant Publications (Appendix 2)- not included here.
The second volume of the series, Design and Implementation of
Sediment Quality Investigations , describes the recommended
procedures for designing and implementing sediment quality assessment
programs. More specifically, Volume II provides an overview of
the recommended framework for assessing and managing sediment quality
conditions is presented in this document (Chapter 2). In addition,
Volume II describes the recommended procedures for conducting preliminary
and detailed site investigations to assess sediment quality conditions
(Chapters 3 and 4). Furthermore, the factors that need to be considered
in the development of sampling and analysis plans for assessing
contaminated sediments are described (Chapter 5). Supplemental
guidance on the design of sediment sampling programs, on the evaluation
of sediment quality data, and on the management of contaminated
sediment is provided in the Appendices to Volume II. The appendices
of this document also describe the types and objectives of sediment
quality assessments that are commonly conducted in freshwater ecosystems.
The third volume in the series, Interpretation of the Results
of Sediment Quality Investigations , describes the four
types of information that are commonly used to assess contaminated
sediments, including sediment and pore-water chemistry data (Chapter
2), sediment toxicity data (Chapter 3), benthic invertebrate community
structure data (Chapter 4), and bioaccumulation data (Chapter 5).
Some of the other tools that can be used to support assessments
of sediment quality conditions are also briefly described (e.g.,
fish health assessments; Chapter 6). The information compiled on
each of the tools includes: descriptions of its applications, advantages,
and limitations; discussions on the availability of standard methods,
the evaluation of data quality, methodological uncertainty, and
the interpretation of associated data; and, recommendations to
guide the use of each of these individual indicators of sediment
quality conditions. Furthermore, guidance is provided on the interpretation
of data on multiple indicators of sediment quality conditions (Chapter
7). Together, the information provided in the three-volume series
is intended to further support the design and implementation of
focused sediment quality assessment programs.
Don Cox has researched the aquatic herbicides used for aquatic weed
control by Citrus county (see county web site: http://www.bocc.citrus.fl.us/pubworks/aquatics/herbicides/herbicides.htm).
The pdf files found at this site are:
Agrisolutions 2, 4-D Amine 4 (http://www.bocc.citrus.fl.us/pubworks/aquatics/herbicides/agrisolutions.pdf)
Aqua
Start (http://www.bocc.citrus.fl.us/pubworks/aquatics/herbicides/aqua_star.pdf)
Aquathol
K (http://www.bocc.citrus.fl.us/pubworks/aquatics/herbicides/aquathol_k.pdf)
Aquathol
Super K (http://www.bocc.citrus.fl.us/pubworks/aquatics/herbicides/aquathol_superk.pdf)
Reward
(http://www.bocc.citrus.fl.us/pubworks/aquatics/herbicides/reward.pdf)
Sonar
A.S (http://www.bocc.citrus.fl.us/pubworks/aquatics/herbicides/sonar_as.pdf)
Sonar
PR (http://www.bocc.citrus.fl.us/pubworks/aquatics/herbicides/sonar_pr.pdf)
Sonar
SRP (http://www.bocc.citrus.fl.us/pubworks/aquatics/herbicides/sonar_srp.pdf)
He has been able to identify five out of six herbicides found in the
eight herbicides used by the county. They are:
2,4-Dichloro-phenoxyacetic acid found in Agrisolutions 2, 4-D Amine
4 http://www.epa.gov/safewater/dwh/c-soc/24-d.html
Diquat found in Reward http://www.epa.gov/safewater/dwh/t-soc/diquat.html
Endothal found in Aquathol and Aquathol k http://www.epa.gov/safewater/dwh/t-soc/endothal.html
Glyshosat found in AquaStar http://www.epa.gov/safewater/dwh/c-soc/glyphosa.html
Fluridone found in Sonar A.S http://www.pesticideinfo.org/
The active ingredients found in these aquatic weed control herbicides
are 2, 4-Dichloro-phenoxyacetic acid, Diquat dibromide, Dipotassium
of endothall, Glyphosate, and Fluridone that are found in Agrisolutions,
Reward, Aquathol K, Aquathol Super K, Aqua-star, and Sonar respectively.
EPA has provided the information on the Environmental fate of
the herbicide, for example, Diquat "When absorbed to sediment,
little or no degradation probably occurs. In any case, the diquat disappears
from the water in 2-4 weeks" It is the absorption
into the sediment that creates the toxic problem.
These herbicides can generate toxicity by continual use, especially
during drought periods. Starting back in the 1970's, aquatic weed
control utilized copper-based and several other types of herbicide formulations
until the late 90's have created a toxic problem with the new herbicides
now being used. (see below, extract from page 20 of Kings Bay/Crystal
River Florida: A Conceptual Proposal To Restore A Submerged Macrophyte
Ecosystem Through Adaptive Management Rather Than Maintenance Control
by Jason Evans, School of Natural Resources and the Environment, University
of Florida, April 2006).
Early hydrilla ( Hydrilla verticillata) control efforts
within Kings Bay were varied and largely ineffective, including
a now notorious attempt to control hydrilla (Hydrilla verticillata)
through the application of large amounts of sulfuric acid obtained
from a nearby phosphate mine into the Hunter Springs area of
Kings Bay. While an initial report indicated somewhat favorable
results from the sulfuric acid treatment method (Phillipy 1966),
aquatic plant managers later suggested that this treatment had
only temporary effects on hydrilla ( Hydrilla verticillata)
and severe detrimental effects on both fish and desirable aquatic
vegetation (Friedman 1987). A more long-term hydrilla (Hydrilla
verticillata) treatment program using a combination of copper-based
and several other types of herbicide formulations was instituted
in the 1970s (Haller et al. 1983). However, this program was
also considered by many citizens and managers to be ineffective
and counter-productive (see Dick 1989), and was eventually abandoned
after elevated levels of copper were detected in Kings Bay's
sediments and the organs of deceased manatees (Trichecus
manatus) (O'Shea et al. 1984; Facemire 1991; Leslie 1992;
SWFWMD 2000). A hydrilla ( Hydrilla verticillata) management
program based upon shredding, mechanical harvest in navigational
trails, and limited application of non-copper containing herbicide
formulations of diquat, endothall, and flurodine was instituted
in the late 1980s (Dick 1989; Cowell and Botts 1994) and remains
the foundation of current hydrilla (Hydrilla verticillata)
management within Kings Bay (Interagency Working Group 2005). |
Bioaccumulation (see EPA - A Guidance Manual to Support the
Assessment of Contaminated Sediments in Freshwater Ecosystems, Volume
III (see Executive Summary above) — Interpretation of the Results of Sediment Quality Investigations
from EPA, see Glossary of Terms extract below). It is the bioaccumulative
effect of herbicides in sediment(s) that can present a toxic problem
when released by dredging or grubbing the lake and bay bottoms. Now,
factor in the Bioaccumulation of various herbicides applied in Citrus
County, and you may well have a toxic soup of sediments just like the copper/herbicide/pesticides
that are found in Kings Bay sediments. Copper sediments react negatively
with a lot of the common herbicides and pesticides according to EPA
studies on Bioaccumulation in Florida (see McDonald studies in Florida,
Bioaccumulation Series, http://www.epa.gov/waterscience/cs/pubs.htm ).
Ecotoxicity — Found on the Fluoride Action Network Pesticide
Project, (http://www.pesticideinfo.org/Index.html)
Pesticide Action Network, North America, Aquatic Ecotoxicity for Fluridone
for Sonar Products containing Fluridone have identified morbidity in
several organism groups. The following summary was given for four groups.
| Summary of Acute Toxicity for Organism Group |
| Organism Group |
Average Acute Toxicity |
Acute Toxicity Range |
| Crustaceans |
Slightly Toxic |
Slight to Moderate Toxicity |
| Fish |
Slightly Toxic |
Slight to Moderate Toxicity |
| Molluscs |
Moderately Toxic |
Moderate Toxicity |
| Zooplankton |
Slightly Toxic |
Slight to Moderate Toxicity |
One of the major sources contributing to the Bioaccumulation of toxic
sediments is golf course* and street run off into Kings Bay and local
waters. Arsenic is one of the contaminates that have been found on
and in the ground water at South Florida golf courses at unhealthful
levels. Arsenic, like the copper sediments, can react negatively with
the application of herbicides and pesticides in the shallow waters
of bay or lakes.
* DERM Technical Report, Environmental Quality Monitoring at Five
Municipal Golf Courses in Miami-Dade County, Prepared By
the Department Of Environmental Resources Management in cooperation
with the Florida Department Of Agriculture And Consumer Services,
Final Report, December 2002.
Don Cox
|
