Elizabeth River Tributyltin Monitoring Program 1999-2006 : A Report to the Virginia Department of Environmental Quality Tidewater Regional Office

The purpose of this project was to implement a study in 1999/2000 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. Subsequent years of sampling have documented spatial and temporal trends in TBT and are described in this report

Elizabeth River TBT Monitoring Report on TBT Methodology Detection Limit, Precision and Linearity

The purpose of this project was to determine the accuracy, precision, linearity and Method Detection Limit (MDL) for tributyltin (TBT) analytical techniques available at the Virginia Institute of Marine Science prior to implementing an environmental monitoring program in the Elizabeth River, Virginia. This precursory work is to document the ability of analytical techniques to accurately detect TBT in ambient water samples at concentrations of 1 ng/L and greater

Investigation of tributyltin: Water/sediment interactions

Tributyltin (TBT) and its degradation products dibutyltin (DBT) and monobutyltin (MBT) have been quantitatively analyzed in environmental water samples using gas chromatography with flame photometric detection and gas chromatography/mass spectrometry (GC/MS). The butyltins were extracted from environmental samples with hexane/0.2% tropolone and derivatized with hexyl magnesium bromide to form hexylbutyltins. Full scanning GC/MS was used for confirmation of peak identifications and quantification was done by selective ion monitoring (methane chemical ionization) at m/z 319 (TBT) and m/z 347 (DBT, MBT and tripentyltin, the internal standard). Calibration curves were linear and detection limits were less than 2 ngL&\sp{lcub}-1{rcub}&. GC/MS and GC with flame photometric detection were compared as quantification methods and were shown to give similar results at the low ngL&\sp{lcub}-1{rcub}& levels. Water samples from Southern Chesapeake Bay were analyzed for TBT in areas of high boating activity. Several sites around a marina were sampled at repeated intervals. High spatial and temporal variability was noted. Reproducible concentration gradients were apparent, with the highest TBT levels near marinas and boatyards. Equilibrium sorption of TBT was measured on selected estuarine and freshwater sediments. Isotherms from twenty-four hour sorption and desorption equilibrations were linear with sorption coefficients between 1.1 &\times& 10&\sp2& and 8.2 &\times& 10&\sp3& Lkg&\sp{lcub}-1{rcub}&. Sorption coefficients decreased with increasing salinity and varied by a factor of two over the salinity range 0-34&\perthous&. Desorption kinetics were measured and indicated an initial fast rate followed by a slower rate. Water and sediment concentrations for TBT at locations in the Chesapeake Bay system were used to calculate apparent sorption coefficients that generally agreed with laboratory measured sorption coefficients. Exceptionally high apparent sorption coefficients were found near areas of high vessel activity and may be the result of TBT paint chips in the sediment

A Manual for the Analysis of Butyltins in Environmental Samples

The Virginia Institute of Marine Science (VIMS) has developed methods for the analysis of tributyltin (TBT) in environmental samples. These methods have been published in the scientific literature where they are freely available to the public. When used by skilled analysts and supported by appropriate quality assurance and quality control procedures (QA/QC), we believe these methods, as well as other published analytical methods for TBT, can provide accurate and precise results. As in any environmental analysis, method performance is a function of the sample type, available instrumentation and skill and care taken by laboratory workers. The suitability of the data produced will only be confirmed by proper QA/QC in the laboratory. At the request of the Virginia Department of Environmental Quality (DEQ), the Virginia Institute of Marine Science has prepared this laboratory manual as an advisory to those interested in methods for analysis of TBT in environmental samples. This manual is based on the previously published methods developed at VIMS and describes procedures for the analysis of TBT in water, sediment and biota samples. This effort is not intended to endorse these techniques as the only suitable methods for butyltin analysis, but is intended to provide detailed information on procedures which have been developed and successfully used at VIMS for the past ten years. It contains a higher level of detail than previous publications and also incorporates any recent changes in procedures, as well as listing possible sources for reagents and standards. This manual also contains a bibliography which lists published VIMS methods as well as other literature citations in which alternative techniques for the analysis of TBT may be found

Body burden of polycyclic aromatic hydrocarbons and tributyltin in hard clams, Mercenaria mercenaria from the Elizabeth River, Va

The Elizabeth River, contaminated with PAH, TBT, and heavy metals, is potentially home to a variety of estuarine invertebrates of commercial importance, notably oysters, hard clams, and crabs. Harvestable oysters have virtually disappeared from the system, but it has been rumored among commercial fishermen that a population of small (little neck to cherrystone) hard clams (Mercenaria mercenaria) exists within the Elizabeth River system. These clams are of serious interest to commercial clammers in the area as a previously unharvested source of market-size clams. Crabs of a harvestable size are also reasonably abundant throughout this river according to local fishermen. The Elizabeth River is presently closed to any type of commercial bivalve harvest because of bacterial and chemical contamination. Chemical contaminants of concern include heavy metals (including organotin compounds), pesticides, and PAHs. If these factors, bacterial or chemical, were shown to pose no human health risk after suitable depuration, the river could conceivably be opened to the taking of bivalve species

Kepone in the James River Estuary: Past, Current and Future Trends

In late 1975, a manufacturing facility in Hopewell, VA had not only exposed workers to the chlorinated pesticide, Kepone, but had also severely contaminated the James River estuary. To assess the potential risk to the public, Virginia initiated a finfish-monitoring program in late 1975. Over the next 40 years over 13,000 samples were collected from the James River and Chesapeake Bay and analyzed for Kepone. Kepone production was eventually banned worldwide. The average Kepone concentrations found in most species began falling when the production of Kepone ended, but the averages remained over the action limit of 0.3 mgkg-1 until the early 1980s. By 1988, few fish contained average Kepone concentrations greater than the action limit. Kepone was still detected (\u3e0.01 mgkg-1 wet weight) in the majority of white perch and striped bass samples taken from the James River in 2009 and a fish consumption advisory is still in effect over forty years after the source of contamination was removed. Due to state budget cuts, monitoring of Kepone has not been conducted since 2009. As part of its 40th Anniversary, the Virginia Environmental Endowment -- which was established as part of the Kepone pollution court settlement in 1977 -- requested that VIMS conduct an updated study of the current levels of Kepone in the James River

Evaluation of a rapid biosensor tool for measuring PAH availability in petroleum-impacted sediment

Decades of research have shown that the concentration of freely dissolved PAH (Cfree) in sediment correlates with PAH bioavailability and toxicity to aquatic organisms. Passive sampling techniques and models have been used for measuring and predicting Cfree, respectively, but these techniques require weeks for analytical chemical measurements and data evaluation. This study evaluated the performance of a portable, field-deployable antibody-based PAH biosensor method that can provide measurements of PAH Cfree within a matter of minutes using a small volume of mechanically-extracted sediment porewater. Four sediments with a wide range of PAHs (ΣPAH 2.4 to 307 mg/kg) derived from petroleum, creosote, and mixed urban sources, were analyzed via three methods: 1) bulk chemistry analysis; 2) ex situ sediment passive sampling; and 3) biosensor analysis of mechanically-extracted sediment porewater. Mean ΣPAH Cfree determined by the biosensor for the four sediments (3.1 to 55 µg/L) were within a factor of 1.1 (on average) compared to values determined by the passive samplers (2.0 to 52 µg/L). All mean values differed by a factor of 3 or less. The biosensor was also useful in identifying sediments that are likely to be non-toxic to benthic invertebrates. In two of the four sediments, biosensor results of 20 and 55 µg/L exceeded a potential risk-based screening level of 10 µg/L, indicating toxicity could not be ruled out. PAH Toxic Units (ΣTU) measured in these two sediments using the passive sampler Cfree results were also greater than the ΣTU threshold of 1 (6.7 and 5.8, respectively), confirming the conclusions reached with the biosensor. In contrast, the other two sediments were identified as non-toxic by both the biosensor (3.1 and 4.3 µg/L) and the passive sampler (ΣTUs of 0.34 and 0.039). These results indicate that the biosensor is a promising tool for rapid screening of sediments potentially-impacted with PAHs

A Peters cycle at the end of the cosmic ray spectrum?

We investigate the degree to which current ultrahigh energy cosmic ray observations above the ankle support a common maximum rigidity for all nuclei, often called a Peters cycle, over alternative scenarios for the cosmic ray spectra escaping sources. We show that a Peters cycle is not generally supported by the data when compared with these alternatives. We explore the observational signatures of non-Peters cycle scenarios, and the opportunities to explore both ultrahigh energy cosmic ray source conditions, as well as, physics beyond the Standard model they present

Data-driven analysis for understanding ultrahigh energy cosmic ray source spectra

One of the most challenging open questions regarding the origin of ultrahigh energy cosmic rays (UHECRs) deals with the shape of the source emission spectra. A commonly-used simplifying assumption is that the source spectra of the highest energy cosmic rays trace a Peters cycle, in which the maximum cosmic-ray energy scales linearly with $Z$, i.e., with the charge of the UHECR in units of the proton charge. However, this would only be a natural assumption for models in which UHECRs escape the acceleration region without suffering significant energy losses. In most cases, however, UHECRs interact in the acceleration region and/or in the source environment changing the shape of the source emission spectra. Energy losses are typically parameterized in terms of $Z$ and the UHECR baryon number $A$, and therefore one would expect the source emission spectra to be a function of both $Z$ and $A$. Taking a pragmatic approach, we investigate whether existing data favor any region of the $(Z,A)$ parameter space. Using data from the Pierre Auger Observatory, we carry out a maximum likelihood analysis of the observed spectrum and nuclear composition to shape the source emission spectra for the various particle species. We also study the impact of possible systematic uncertainties driven by hadronic models describing interactions in the atmosphere