Historical News
Fixed Site Network
Phillipsdale Landing
Water quality was good this week at Phillipsdale Landing. During the first three days of the week, 1.2 inches of precipitation occurred, with the daily maximum, 0.76 inches, measured on December 1. Surface salinity generally decreased over the course of the week, particularly following December 3 in response to the early-week precipitation. Surface salinity was lower than the previous week, averaging 8.71 ppt and ranging from 1.9 ppt to 16.1 ppt. Bottom salinity averaged 23.3 ppt and ranged from 5.0 ppt to 30.1 ppt. Water temperatures at both depths continued to cool into the first week of December; surface temperatures for the week averaged 3.6°C and bottom temperatures averaged 6.7°C. Dissolved oxygen (DO) concentrations continued to remain above the hypoxia threshold (> 2.9 mg/L) at both depths. Surface DO averaged 12.2 mg/L, with a minimum of 9.8 mg/L and bottom DO averaged 10.4 mg/L with a minimum of 7.1 mg/L. Surface chlorophyll-a remained low all week, averaging 1.8 ug/L with a maximum of 3.6 ug/L. Note that tidal fluctuations and Blackstone River flow greatly influence water column DO, temperature, and salinity at this location.
Bullock Reach
Please note, the Bullock Reach sondes were removed for the 2019 monitoring season on November 19.
Fixed Site Network
Phillipsdale Landing
Water quality was good this week at Phillipsdale Landing. The sondes were changed out for routine maintenance on the morning of November 26. Approximately 1.6 inches of precipitation was recorded over the week, with most of the rain occurring on November 24. Surface salinity decreased at Phillipsdale in response to the precipitation and increase in freshwater flow from the Blackstone River. Surface salinity averaged 11.1 ppt and ranged from 2.2 ppt to 24.1 ppt while bottom salinity averaged 21.2 ppt and ranged from 6.4 ppt to 29.3 ppt. Compared to the rest of the November, the water temperatures at both depths continued to cool. Surface temperatures for the week averaged 6.8°C and bottom temperatures averaged 8.1°C. Dissolved oxygen (DO) concentrations continue to be good for the week, remaining above the hypoxia threshold (2.9 mg/L) at both depths. Surface DO averaged 10.9 mg/L with a minimum of 8.3 mg/L and bottom DO averaged 9.2 mg/L with a minimum of 7.8 mg/L. Surface chlorophyll-a remained low all week, averaging 2.1 ug/L with a maximum of 5.4 ug/L. Note that tidal fluctuations and Blackstone River flow greatly influence water column DO, temperature, and salinity at this location.
Bullock Reach
Due to remote data transfer issues, there are no current Bullock Reach data available since October 19. The data are being internally logged by the sondes, and will be updated to the blog as they become available.
Please note, the Bullock Reach sondes were removed for the 2019 season on November 19.
R/V Monitor's Blog
On Wednesday, December 4th, the crew of the R/V Monitor was out on the upper Bay collecting nutrients samples, taking Secchi Disk water clarity measurements, 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 Fern collected the samples and data. It was a very cloudy day with no wind. A heavy fog in the early morning resulted in a delay getting underway. The photo featured this day shows Field's Point in the foreground with the City of Providence in the background.
Phytoplankton Sampling
Phytoplankton samples were collected on November 20, 2019 at Bullock's Reach and analyzed in the laboratory shortly after collection. It was a cloudy and raw day with a northwest wind, about 10 knots, on Narragansett Bay. Sondes data revealed the surface water temperature was 8.54oC, salinity was 27.38 psu, and chlorophyll a was 2.3 ug/L. The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was a tan color and had a short filter time. The tow net sample was analyzed qualitatively for microorganisms using 100x phase contrast microscopy. The whole water sample was analyzed quantitatively under 200x phase contrast microscopy. A Hensen Stempel pipette was used to accurately deliver 1ml of sample to a Sedge-wick Rafter chamber. This analysis revealed a total of 408,000 cells per Liter. The most predominant phytoplankton was Leptocylindrus spp.at 196,000 cells/L. The flagellates were found at 52,000 cells/L. Representative genera include Skeletonema spp., Guinardia, and Chaetoceros spp.
200x phase contrast micrograph of Guinardia spp.
Nutrients Sampling
Nutrient samples were collected at seven river stations and one bay station (Phillipsdale Landing; surface and bottom) on October 23, 2019. On October 24, 2019, nutrient samples were collected at six bay stations (surface and bottom). On October 23, approximately half an inch of rainfall was recorded in the early morning hours.
Among the river stations sampled, highest total nitrogen (TN) was measured at Ten Mile River at Roger Williams Avenue, at 1030 ppb. Greatest total dissolved nitrogen (TDN), 998 ppb, occurred in a single sample at the Moshassuck River at Mill Street site, however, the average of duplicate samples at this site (938 ppb) was lower than the TDN concentration measured at Ten Mile River at Roger Williams Avenue (954 ppb). Dissolved inorganic nitrogen (DIN) was greatest (637 ppb) at the Pawtuxet River at Broad Street site. Lowest TN, TDN, and DIN values occurred at Moshassuck River at Higginson Avenue, with results of 504 ppb, 439 ppb, and 208 ppb, respectively.
Among the bay stations sampled, greatest TN (1000 ppb) and TDN (817 ppb) in surface waters occurred at Phillipsdale Landing, however, this location was sampled following some rainfall during the morning hours of October 23. Among the bay stations sampled the following day, highest TN and TDN results were observed at Pawtuxet Cove, at 940 ppb and 613 ppb, respectively. The greatest DIN concentration, 631 ppb, was also measured at Pawtuxet Cove. Lowest TN (564 ppb) was observed in one of two duplicate samples at Edgewood Yacht Club surface, however, the average of both duplicates at this site (594 ppb) was higher than results from Bullock Reach Buoy (572 ppb). Bullock Reach Buoy also had the lowest TDN value, at 233 ppb. Finally, lowest DIN occurred at Conimicut Point, at 194 ppb.
Results from sampling on November 6 and 20 are pending analysis. The next scheduled date of sampling is December 4, 2019.
