Historical News
R/V Monitor's Blog
The crew of the R/V Monitor was out on the upper Bay twice this week. First, on Tuesday, November 17th, the crew dismantled the components from the Bullock's Reach buoy for the season, readying the buoy for removal next week. They also disassembled and removed the temporary buoy located in Pawtuxet Cove for the season. Jeff captained the boat while monitoring professionals Sara, Mike and Daryll worked on the buoys. It was a sunny but brisk day with calm winds and water. On Wednesday, November 18th, the crew returned to the upper Bay collecting nutrients samples, taking Secchi Disk and Par sensor water clarity measurements, conducting waterr 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. Jeff captained the boat while monitoring professionals Bekki and Mike collected the samples and data. It was a sunny but cold day with 10 to 15 knot winds from the north-northwest. There were 3 foot swells at the Bullock's Reach and Conimicut sampling locations preventing nutrients sample collections. The water was calmer at the northern stations and samples were able to be collected. The featured photo was taken at Pawtuxet Cove.
Surface Mapping
Data were collected on November 18, 2020 while the R/V Monitor was underway collecting nutrient samples and performing vertical profiles in the Providence River estuary. The chlorophyll concentrations were good in the areas surveyed. From north to south, average chlorophyll concentrations were as follows: Edgewood Shoals area (1.70 µg/L), Pawtuxet River area (1.70 µg/L), and Lower Providence River area (1.69 µg/L). Overall, chlorophyll ranged between 0.30 and 3.40 µg/L with an overall average of 1.70 µg/L. The chlorophyll data from this date are presented in the map below:
Water Column Clarity
Water clarity was measured at six stations in the Providence and Seekonk Rivers on November 4, 2020. Moderate precipitation occurred over the five days prior to the survey, with a total of 1.2 inches (rain and snowmelt) documented at TF Green. Despite the wet weather, water clarity increased by 0.84 m from the previous survey. The greatest increases in clarity occurred at the downstream sites Bullock Reach and Conimicut Point; clarity at these sites increased by approximately 2.17 m since the last survey. Decreases in water clarity were observed at two sites, with the greatest decrease from last week (0.53 m) observed at Edgewood Yacht Club. Secchi depth averaged 3.91 m and ranged from 2.70 m at Edgewood Yacht Club and Pawtuxet Cove to 5.80 m at Conimicut Point. There was no apparent gradient in clarity from north to south this week.
Nutrients Sampling
Among the river stations sampled, nitrogen concentrations were lowest at Palmer River at Rt. 6 and highest at Ten Mile River at Central Avenue. At the Palmer River at Rt. 6 site, total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were 557 ppb, 264 ppb, and 13 ppb, respectively. At the Ten Mile River at Central Avenue site, TN measured 3,370 ppb, TDN was 3,530 ppb, and DIN was 3,130 ppb.
Among the Bay stations sampled, highest surface nitrogen concentrations were observed at Pawtuxet Cove. At this site, TN, TDN, and DIN concentrations were 893 ppb, 841 ppb, and 569 ppb, respectively. Lowest surface TN concentration (333 ppb, average of duplicates) was observed at Conimicut Point. Concentrations of TDN were low at both Conimicut Point and Bullock Reach Buoy, measuring 186 ppb at both locations. The lowest measured surface DIN concentration (13 ppb) occurred at Conimicut Point, Bullock Reach Buoy, and Phillipsdale Landing. Bay chlorophyll a concentrations averaged 13.7 ug/L, and a maximum result of 54.8 ug/L was recorded at Phillipsdale Landing.
Results from nutrients sampling on October 21 and November 4 are pending analysis. The next scheduled date of nutrients sampling is November 18.
Nutrients Sampling
Nutrient samples were collected from the surface waters at eight bay stations on September 23rd; samples were also collected from bottom waters at one of these stations. Nutrient samples were also collected at fourteen local and border river stations. In the three days prior to sampling there was no recorded rainfall.
Among the river stations samples, 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, concentrations for TN, TDN, and DIN were 2,340 ppb, 2,460 ppb, and 1,821 ppb, respectively. The lowest TN (516 ppb) and TDN (252 ppb) results were observed at Pawtuxet River at Broad Street, while the lowest TDN (13 ppb) result was observed at Palmer River at Route 6.
Among the bay stations sampled, the highest TN (924 ppb) in surface waters was observed at Phillipsdale Landing, with the greatest surface TDN (455 ppb), and DIN (228 ppb) observed at Pawtuxet River at Broad Street. The lowest surface TN (422 ppb) result was observed at Edgewood Yacht Club, while the lowest surface TDN (187 ppb) and DIN (13 ppb) results were observed at Conimicut Point and Phillipsdale Landing, respectively. Chlorophyll a concentrations averaged 11.7 ug/L, with a maximum result of 50.2 ug/L occurring at Phillipsdale Landing.
Results from nutrients sampling on October 7th and 21st are pending analysis. The next scheduled date of sampling is November 4th, 2020.
