Project Title: Developing and Applying A New In Situ Technology for the Investigation of Episodic Contaminant Transport Events within Estuaries
Principal Investigator(s): John W. King, Alfred K. Hanson, Christopher R. Kincaid, Elizabeth Lacey, James G. Quinn.

Accomplishments
Scheduled Tasks:

1. Equipment tests in outdoor tanks and in Narragansett Bay (4/30, 5/22 and 7/13) with SubChem Systems XZ-Profiler and the SubChemPak Analyzer.
2. Field survey in Narragansett Bay (6/23). SubChem Systems XZ-Profiler was towed from north of Prudence Island up the Providence River and back (a five hour tow).
3. Two additional seasonal sampling events of sediment and sediment trap material from the stations located throughout Narragansett Bay.
4. Laboratory analysis of sediment and sediment trap material. Analyses included grain size, simultaneously extracted metal/acid volatile sulfide concentrations (of sediment samples), and organic contaminant concentrations (of sediment from selected sediment trap stations).

Progress on Tasks

1. SubChem field cruises on May 22 and July 23, 2001.
2. Fieldwork in March 2001 and June 2001 to collect sediment samples and retrieve/deploy sediment traps.
3. After sample collection, bottom sediment is subsampled for grain size and trace metal analysis. Separate aliquots of bottom sediment are collected in the field for SEM-AVS analysis. The sediment trap material is weighed to determine the flux of material into the location and then the material is subsampled for grain size, trace metal and organic contaminant analyses.
4. Presentations at Meetings.
   • Egli, P., A. Hanson and W.DeLeo, April 2001. "In Situ Measurement of Fine-Scale Nutrient Gradients in Narragansett Bay, RI". Poster presentation at The Oceanography Society (TOS) Annual Meeting held in Miami, FL.
   • DeLeo, W., A. Hanson and P. Egli, April 2001. "3-D Mapping of Hypoxia and Nutrient Plume Events in Narragansett Bay, RI". Poster presentation at The Oceanography Society (TOS) Annual Meeting held in Miami, FL.

Difficulties Encountered

1. We had some electronic difficulties with instrumentation during the early spring that were subsequently corrected.
2. In response to the low number of sediment traps recovered during the previous sampling events, the traps deployed in March 2001 had subsurface floats and no surface buoys. Unfortunately, none of these subsurface traps were found during the June 2001 sampling event.

Anticipated Success in Meeting Project Objectives in Scheduled Project Period

1. We have made good progress towards attaining our project objectives and attaining our milestones.
2. We have documented the general pattern of trace metal contamination in the NERRS area.
3. We have demonstrated that plumes of resuspended contaminants from the Providence River and Upper Narragansett Bay contribute to trace metal and organic contamination in sediments in the NERRS area.
4. We have also developed and had successful field trials with the SubChemPak Analyzer and XZ-Profiler. This new oceanographic equipment is now commercially available from SubChem Systems, Inc.
5. The majority of the sample analyses have been finished; the remaining analyses will be presented in the next progress report (February 2002).

Preliminary Results
The following data and results are from the seasonal sampling events and the test deployments of the SubChemPak Analyzer and XZ-Profiler in Narragansett Bay. Figure 1 is a location map for the CICEET stations.

Seasonal Sampling of sediments and settling particles: Samples collected during this report period were Round 5 in March 2001 and Round 6 in June 2001.

The potential bioavailability of trace metals may be related to the amount of acid volatile sulfide (AVS) that is present. AVS has been shown to bind certain trace metals (cadmium, copper, lead, nickel and zinc, the simultaneously extracted metals or SEMs) on a molar basis. AVS is produced by sulfate reducing bacteria and has been related to the overlying water temperature. Therefore, AVS concentrations may vary seasonally. Figure 2 shows the seasonal variability in AVS at stations 3 and 4. There are low AVS concentrations in the winter when there is a lower overlying water temperature and less AVS production by the bacteria. The AVS concentrations at these particular stations are significantly greater than the corresponding SEM concentrations. During Round 6, samples were only collected from Stations 2, 5 and 11 which had historically showed seasonal remobilization of the trace metals (Figure 2).

The concentrations of the organic contaminants are given in Figures 3a and 3b. In general, the agreement between 2-3 samples collected at the same station over the study is fair to good and no seasonal trends are readily apparent. Highest levels of organic contaminants are observed at station 6 near Sabin Point, which is the northern most station in the Providence River. Concentrations decrease from that site to station 7 at Conimicut Point near the mouth of the river. From that station south, the values either decrease somewhat or remain about the same to station 10 at the southern end of Prudence Island. In a few cases, high levels are seen at station 4 in Potter Cove at the northern end of Prudence Island. Several samples from stations 6 to 4, exceeded the sediment ERM guidelines for PCBs. In addition, 4 samples exceeded the ERL guidelines for PAHs and all samples exceeded those guidelines for PCBs and DDTs.

SubChemPak Analyzer and XZ-Profiler Deployments: The SubChem Systems instrumentation tests in Narragansett Bay for this report period were conducted on May 22, 2001 and July 23, 2001. The deployment on May 22 involved testing different techniques for towing the instrument package (see photo in Figure 4). The deployment on July 23rd involved a five hour tow (~20 nautical miles) from the tip of Prudence Island, up the Providence River, past the Field's Point Sewage Treatment Plant outfall and back. The track of the boat for the initial 2 hour leg upriver is shown in Figure 5. Measurements of nitrate, nitrite, dissolved oxygen, pH, chlorophyll, directional current velocity and other parameters were obtained in real-time while towing the instrument package at 4 knots. The package was undulated between 3 and 10 meters depth (above and below the pycnocline). The ribbon plots shown in Figure 6 depict some of the chemical concentration gradients that were detected, in real-time, during this initial upriver transect. A separate data report is being prepared that will review all the results from the five hour survey.

Tasks and activities for next reporting period
An additional year of funding has been granted for this project. Over the next year, we plan to conduct additional field experiments deploying SubChem's XZ-Profiler to investigate episodic events contaminant transport events. We intend to conduct these experiments sometime during October and April 2001. We are initiating plans to collaborate with the Narragansett Bay Commission and the Rhode Island Department of Environmental Management for these experiments. We also plan on collecting sediment cores from locations adjacent to the NB-NEERs and analyze the sediment for trace metal and organic contaminants. Organic contaminants from sediment samples will provide additional information on the sources transport and fate of contaminants in the Narragansett Bay estuary.

Tasks for the next reporting period

1. A cruise is planned for October 2001 to examine chemical plume activity after a significant storm event.
2. The remaining the sediment and sediment trap analyses will be performed and results for trace metal and organic contaminants will be provided.
3. A web site will be developed with information on both seasonal sampling and results for the study area.

Work plan to accomplish tasks

1. It is anticipated that a storm event can be documented by performing a cruise in October 2001.
2. The remaining sediment analyses will be completed and documented.
3. Web site development will continue.

Concerns or difficulties
No significant problems are anticipated.

Expenditures
The expenditures have included boat time, analytical costs, personnel costs, travel and are within the anticipated range.