Historical News
Surface Mapping
Data was collected on November 21, 2018 while the R/V Monitor was underway collecting nutrient samples and performing vertical profiles in the Providence River estuary. The chlorophyll concentrations were mostly low in areas surveyed. From north to south, average chlorophyll concentrations were as follows: Upper Providence River (16.00 µg/l), Edgewood Shoals area (1.63 µg/l), Pawtuxet River area (1.54 µg/l), and the Lower Providence River (1.06 µg/l). Overall, chlorophyll ranged between non-detectable and 69.90 µg/l with an overall average of 6.08 µg/l. The chlorophyll data from this date is presented in the map below:
Nutrients Sampling
Five bay stations and twelve river stations were sampled for nutrients on October 24, 2018. Surface and bottom waters were sampled at all bay stations. Light rainfall occurred in the five days prior to sampling, with 0.2 inches of recorded precipitation.
Among the river stations sampled, highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) values were measured in the Ten Mile River at Central Avenue, with reported values of 1380 ppb, 1550 ppb, and 1108 ppb, respectively. The Moshassuck River at Higginson Avenue had the lowest measured TN (496 ppb) and TDN (510 ppb) values. Lowest DIN concentrations were observed in the Palmer River at Route 6, at 317 ppb.
Highest bay surface nutrient concentrations occurred at Phillipsdale Landing, with TN, TDN, and DIN concentrations of 927 ppb, 761 ppb, and 640 ppb, respectively. Conimicut Point demonstrated the lowest nitrogen values, at 803 ppb TN, 441 ppb TDN, and 313 ppb DIN. Chlorophyll a averaged 1.7 ug/L, ranging from 1.0 ug/L at Conimicut Point to 3.2 ug/L at Edgewood Yacht Club.
Results from nutrient sampling completed on November 7 and November 21 are pending final analysis from the NBC Laboratory. The next anticipated date of sampling is December 5, 2018.
Water Column Profiles
Water column profiles were measured at three sites in the Seekonk and Providence Rivers on November 7, 2018. A total of 2.41 inches of precipitation was recorded in the five days prior to sampling; the day before sampling, 0.72 inches of rainfall occurred. Some salinity-driven stratification was evident, as recent precipitation enhanced surface freshwater inputs.
Highest water column salinity was observed at Edgewood Shoal, where surface salinity measured 15.6 psu and bottom salinity measured 27.5 psu. Lowest surface salinities (around 2.5 psu) were observed at Phillipsdale Landing and Pawtuxet Cove. Phillipsdale Landing and Pawtuxet Cove had bottom salinities of 14 and 13 psu, respectively.
Surface water temperatures were approximately 12.5°C at all sites. Lowest bottom water temperatures (around 12°C) were observed at Phillipsdale Landing. Water temperature at depth was highest at Edgewood Shoal, at 13.3°C.
Hypoxic conditions (dissolved oxygen <2.9 mg/L) were not present at the sites sampled. The maximum dissolved oxygen (DO) concentration, 9.89 mg/L, was observed at Phillipsdale Landing. The minimum DO concentration, 5.65 mg/L, occurred at Edgewood Shoal. Fluorescence was low (<3 mg/m3) at all sites, and maximum fluorescence values (2.0 - 2.2 mg/m3), were observed at Phillipsdale Landing.
Water Column Clarity
Water clarity was measured at seven locations in the Providence and Seekonk Rivers on November 7, 2018. In the five days prior to sampling, 2.41 inches of precipitation was recorded, with 0.72 inches of rain falling on the day prior to sampling. In light of the recent rainfall, average water clarity decreased from the previous week, from 1.9 m to 1.1 m.
Decreases in water clarity were observed at Phillipsdale Landing, India Point Park, Pomham Rocks, Pawtuxet Cove, Bullock Reach and Conimicut Point. Water clarity increased at Edgewood Shoals. Secchi depth ranged from 0.63 m at Pawtuxet Cove to 1.50 m at Bullock Reach. A slight north to south water clarity gradient was present.
R/V Monitor's Blog
On Wednesday, November 7th, the crew of the R/V Monitor was out on the upper Bay collecting nutrients and plankton samples, taking Secchi Disk and Par sensor water clarity measurements, conducting water column profiles using the Seabird instrument, and conducting real-time surface mapping of water quality parameters, including dissolved oxygen, chlorophyll, water temperature, salinity, and pH, all in an effort to document water quality improvements associated with NBC construction projects. Sara captained the boat while monitoring professionals Mike and Bekki collected the samples and data. It was a clear and sunny day with wind out of the southwest, making the waters choppy. The photo featured this day is of the Seabird instrument being deployed for a profile.
