Week of July 18 - 24, 2021
Water Column Profiles
Water column profiles were conducted at eight locations in the Providence and Seekonk Rivers using a Seabird profiling instrument on July 21, 2021. Conditions leading up to the survey included a large rainstorm four days prior (1.52 inches) and light rain totaling 0.11 inches over the two to three days prior, according to data from T.F. Green. Field staff noted a strong current during the survey.
The lowest salinities this week were observed at Phillipsdale Landing, the site furthest from the main-body of the Bay and near several major freshwater sources. At this site, salinity was less than 5 psu from the surface to 4 m depth. The maximum salinity at the bottom at Phillipsdale was just 19 psu. Salinities were highest at Bullock Reach, where surface waters measured 21 psu and bottom waters measured 30 psu (note Conimicut Point bottom water salinity was similarly high). Surface temperatures ranged from 22°C at Edgewood Yacht Club, India Point Park, and Pomham Rocks to 24°C at Conimicut Point, Bullock Reach, and Point St. Bridge. Bottom temperatures were coolest (19°C) at Pomham Rocks and warmest (23°C) at Point St. Bridge.
Dissolved oxygen (DO) concentrations were low this week, with hypoxic conditions (e.g., DO <2.9 mg/L) observed at almost all sites. The only site with DO levels remaining above this threshold was Phillipsdale Landing, thanks to the heavy influx of freshwater flows from area rivers following rain events. DO at Phillipsdale was between 5 and 6 mg/L through the full water column. The site with the lowest DO this week was Edgewood Yacht Club, where hypoxic conditions were observed from 1.75 m and deeper, hitting a minimum of <0.1 mg/L at the bottom. Maximum fluorescence this week was observed in surface waters at Conimicut Point and Bullock Reach. Please note that due to a quality control issue, numerical fluorescence data are not posted at this time.
Week of July 11 - 17, 2021
Water Column Profiles
Water column profiles were conducted at six locations in the Providence River using a Seabird profiling instrument on July 15, 2021. Profiles from two sites (Edgewood Yacht Club and Edgewood Shoal) show signs of sediment interference, were deemed problematic, and are excluded from analysis. Conditions leading up to the survey included a major rainstorm six days prior (2.05 inches) and a moderate storm (0.63 inches) three days prior, according to data from T.F. Green.
The lowest salinities this week were observed at Pawtuxet Cove, with 1.9 psu at the surface and 20.0 psu in bottom waters. This site is near the major freshwater source of the Pawtuxet River, likely flowing at high rates following recent rain events. The highest salinities were observed at the sites closest to the main-body of the Bay, like Conimicut Point where salinity ranged from approximately 15.0 psu at the surface to 30.4 psu at the bottom. Bottom salinities at Bullock Reach were similar. Surface temperatures ranged from 21°C at Pomham Rocks to 23°C at Conimicut Point and Bullock Reach. Bottom temperatures ranged from 19°C at Conimicut Point and Bullock Reach to 21°C at Pawtuxet Cove.
Dissolved oxygen (DO) concentrations were variable this week. Hypoxic conditions (e.g., DO <2.9 mg/L) were observed in the bottom waters of Pomham Rocks and mid-depth at Bullock Reach and Conimicut Point. The minimum DO was 1.9 mg/L, in Pomham Rocks bottom waters. The highest DO concentrations were observed in surface waters at Bullock Reach and Conimicut Point, at 7 mg/L. Please note that due to a quality control issue, numerical fluorescence data are not posted at this time.
Week of July 4 - 10, 2021
Water Column Profiles
Water column profiles were conducted at eight locations in the Providence and Seekonk Rivers using a Seabird profiling instrument on July 7, 2021. Conditions leading up to the survey were relatively wet, with 1.75 inches of rainfall recorded at T.F. Green over the five days prior. Evidence of density stratification was observed at almost all sites.
Surface salinities this week ranged from 2 psu at Phillipsdale Landing to 24 psu at Pomham Rocks and Edgewood Yacht Club. Bottom salinities ranged from 22 psu at Phillipsdale Landing to 31 psu at Conimicut Point. The highest temperatures were observed at Point St. Bridge, where surface waters reached 23°C and bottom waters were slightly cooler at 21°C. Edgewood Yacht Club and Pomham Rocks had the coolest surface waters at 21°C while the coolest bottom temperatures (18°C) were observed at Conimicut Point.
Dissolved oxygen (DO) concentrations were variable this week. Hypoxic conditions (e.g., DO <2.9 mg/L) were observed in the bottom waters of Edgewood Yacht Club, where DO below 3 m averaged 1.3 mg/L. Among the other sites, DO ranged from 3.1 mg/L to 9.3 mg/L. The highest DO concentrations were associated with relatively high fluorescence values in the sub-surface waters at Bullock Reach and Conimicut Point. Please note that due to a quality control issue, numerical fluorescence data are not posted at this time.
Week of September 19 – 25, 2021
Nutrients Sampling
Nutrient samples were collected from thirteen local and border river stations and one bay station on September 22, 2021. Please note that due to ongoing mechanical issues with the NBC research vessel, R/V Monitor, bay sampling this week was limited to only the surface at Phillipsdale Landing. Weather conditions leading up to the sampling day was mostly dry, with 0.03 inches of recorded rainfall in the five days prior to sampling.
Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were all observed at Ten Mile River at Central Avenue. At this site, surface TN, TDN, and DIN were 1,920 ppb, 1,910 ppb, and 1,556.9 ppb, respectively. The lowest TN (666 ppb) and TDN (533 ppb) were observed at Moshassuck River at Higginson Avenue, while the lowest DIN (216.8 ppb) was observed Coles River at Milford Road.
This week at the Phillipsdale Landing surface, the results for TN, TDN, and DIN were 777 ppb, 615 ppb, and 433 ppb, respectively.
Results from nutrient sampling on September 29 are pending analysis. The next scheduled sample date is October 6.
Week of September 12 – 18, 2021
Nutrients Sampling
Due to ongoing mechanical issues with the NBC research vessel, R/V Monitor, nutrient sampling was only collected from the surface and bottom waters at the Bullock Reach Buoy station on September 14, 2021. Weather conditions leading up to the sampling day were dry, with no recorded rainfall in the five days prior to sampling.
At the Bullock Reach Buoy surface, the results for total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were 619 ppb, 344 ppb, and 153.8 ppb, respectively. In the bottom waters at this site, TN was 490 ppb, TDN was 347 ppb, and DIN was 216.2 ppb.
Results from nutrient sampling on September 22 are pending analysis. The next scheduled sample date is September 29.
