Elizabeth River Tributyltin Monitoring Program

Michael A. Unger

Elizabeth River photo gallery

Link to: 
ELIZABETH RIVER TRIBUTYLTIN MONITORING PROGRAM REPORT: 1999-2006

The purpose of this project is to implement a study that would document the current levels of tributyltin (TBT) in the Elizabeth River and provide baseline data for future efforts to determine the trend of TBT concentrations found in the Elizabeth River Watershed. TBT concentrations can also be compared to non-industrialized areas outside the Elizabeth River to assess the relative status of TBT contamination in this watershed.

BACKGROUND 

The Virginia Department of Environmental Quality, in collaboration with the Elizabeth River Project, has prepared an Elizabeth River Monitoring Program (ERMP) that is designed to describe the trend in environmental conditions relating to five areas of concern to stakeholders. The five primary areas of concern are: sediment quality; water quality; habitat; living resources and quality of life.

This TBT monitoring project began in July of 1999 to evaluate the potential for TBT impacts on water quality in the Elizabeth River. By comparing monitoring results with areas outside the Elizabeth River basin, it will allow managers to assess how the Elizabeth River compares to other nearby, less industrialized regions.

Assessing TBT Regulations

Concern over adverse environmental effects from TBT use in the 1980's led to regulatory actions restricting the use of TBT in France, the United Kingdom and the United States. The Virginia General Assembly in 1987 enacted TBT legislation limiting use of TBT paints to vessels over 25 m in length and set a water quality criteria of 1 ng/L (Code of Virginia, 1987). Legal application of TBT paints to large vessels continues. In October of 2001, the International Maritime Organization (IMO) adopted a convention to prohibit the use of harmful organotins in anti-fouling paints used on ships and will establish a mechanism to prevent the potential future use of other harmful substances in anti-fouling systems. Annex I attached to the Convention and adopted by the Conference states that by an effective date of 1 January 2003, all ships shall not apply or re-apply organotins compounds which act as biocides in anti-fouling systems.

By 1 January 2008 (effective date), ships either:

This applies to all ships (including fixed and floating platforms, floating storage units (FSUs), and Floating Production Storage and Offtake units (FPSOs).

To assess the effectiveness of TBT regulations, the Department of Environmental & Aquatic Animal Health at VIMS began analyzing water samples and biota from various locations around southern Chesapeake Bay. Water column monitoring has continued at nine stations near marina areas every month since 1985 and the resulting data set has shown elevated TBT concentrations in the vicinity of marinas and has documented the variability in spatial and temporal trends. Concentrations have decreased by at least a factor of five at the marina monitoring stations in the last ten years but are still above detection limits (1 ng/L) in most samples.

VIMS continued monitoring TBT in water samples from nine locations in Hampton Creek and Sarah Creek, Virginia. This allows a comparison of TBT concentration trends in water from marina areas with trends determined for the Elizabeth River.

METHODS

Water Column Monitoring: 18 Stations were selected for monitoring sites in the Elizabeth River and Hampton Roads (Figure). Environmental water samples are collected by VIMS personnel bimonthly at 18 E.R. station locations selected by the VADEQ. Sample custody issues are eliminated by utilizing the same  analyze water samples. Once collected, all environmental samples are maintained in locked storage prior to analysis. All vessels used for collecting samples are free of TBT containing antifoulants and water samples are collected in sample storage containers to avoid cross contamination of samples via sampling gear. Samples are collected as near to high slack water as possible and the sampling information recorded on each container and in a field notebook. Water is collected from the top meter of the water column with care to exclude the surface microlayer. Sample bottles are rinsed twice with ambient water prior to collection of the sample. Field blanks were carried on each sampling trip and the samples are kept in the dark on ice in the field for transport back to the laboratory. To document sampling variability, duplicate 2 liter samples are collected at four stations during each sampling trip (>20% replication). Once returned to the laboratory the samples are preserved with HCL to below pH 2 and kept at 4^oC in the dark in a locked cold room prior to analysis.

Tributyltin analysis: Water samples are analyzed for butyltins by an adaptation of the methodology published earlier (Unger et al, 1986 ) which has been described in detail in a manual prepared for the Virginia DEQ (Unger, 1996). This is the same analytical method used in all previous TBT monitoring and assures comparability with historical data. Analysis of extraction blanks (>10%), sample duplicates (>10%), matrix spikes and matrix spike duplicates document the accuracy and precision of these analyses to assure project data objectives are met. The method detection limit is 1 ng/L and has been determined using the procedures recommended by the DEQ and described in detail in the report “Elizabeth River TBT Monitoring Report on TBT Methodology Detection Limit, Precision and Linearity” (Figure).

Left: Scientist extracting TBT from Elizabeth River water samples

Click here for a pdf copy of the manual describing the analysis of butyltins in environmental samples. 

Click here for a pdf copy of the TBT method validation report. 

RESULTS & REPORTS

Link to: 
ELIZABETH RIVER TRIBUTYLTIN MONITORING PROGRAM REPORT: 1999-2006

Comparison with areas outside the Elizabeth River  
Average concentrations for all monitoring stations over the 1999-2002 time period are plotted and compared (Figure). Error bars illustrate one standard deviation of the calculated mean concentration. Long-term monitoring of marina stations by VIMS has shown that average TBT concentrations have been reduced dramatically since legislation limiting TBT application was enacted in the late 1980’s. The results of current monitoring shows that many of the Elizabeth River and Hampton Roads monitoring stations now exceed the average TBT concentrations measured in marina areas.

• All monitoring stations had average yearly TBT concentrations that exceeded the Virginia Water Quality Criteria for TBT (1 ng/L).

• A few stations, near the confluence of the eastern and southern branches, had average concentrations that exceeded 10 ng/L or individual measurements greater than 20 ng/L. Typically, TBT concentrations in the Elizabeth River showed a gradient with the highest levels near the confluence of the Eastern and Southern Branches. (Figure)

• The highest measured concentrations, to date, occurred on September 20, 2001 with several stations near the confluence of the Eastern and Southern Branches exceeding 20 ng/L and the highest measured concentration was greater than 70 ng/L at a station in the Southern Branch. (Figure)

• Code of Virginia, Title 3.1, chap. 14, Article 5, Sections 3.1-249.22-3.1-249.26, 1987.

• Unger, M.A., W.G. MacIntyre, J. Greaves and R.J. Huggett. 1986. GC Determination of Butyltins in Natural Waters by Flame Photometric Detection of Hexyl Derivatives with Mass Spectrometric Confirmation. Chemosphere 15(4):461-470.

• Unger, M.A., 1996. A Manual for the Analysis of Butyltins in Environmental Samples. Prepared for the Virginia Department of Environmental Quality. VIMS Special Report in Applied Marine Science and Engineering #338.

CONTACTS

ACKNOWLEDGMENTS

This work has been funded by the Department of Environmental Quality Elizabeth River Monitoring Program

The following people have been instrumental in the collection and analysis of samples from the Elizabeth River:

Questions/comments regarding the design of this website should be directed to Gregory Mears.

(This page was last updated 05/16/2007 )