Fixed Site Network
Water quality was good this week at Phillipsdale Landing. The sondes were changed out for routine maintenance mid-day on November 13. A portion of the data, approximately 2.5 hours late night November 11 into early morning November 12, was affected by a buoyancy issue and has been excluded from the summary written below. Approximately 0.8 inches of precipitation was recorded on November 12, but salinity did not appear to be impacted greatly. Surface salinity averaged 12.7 ppt and ranged from 2.5 ppt to 22.5 ppt while bottom salinity averaged 22.9 ppt and ranged from 8.1 ppt to 28.5 ppt. Compared to last week, water temperatures at both the surface and bottom cooled this week, with surface temperatures averaging 8.5°C and bottom temperatures averaging 11.2°C. Dissolved oxygen (DO) concentrations this week were good, remaining above the hypoxia threshold (2.9 mg/L) at both depths. Surface DO averaged 9.6 mg/L with a minimum of 7.6 mg/L and bottom DO averaged 7.5 mg/L with a minimum of 6.0 mg/L. Surface chlorophyll-a remained low all week, averaging 2.4 ug/L with a maximum of 5.7 ug/L. Note that tidal fluctuations and Blackstone River flow greatly influence water column DO, temperature, and salinity at this location.
Due to remote data transfer issues, there are no current Bullock Reach data available for this week. The data are being internally logged by the sondes, and will be updated to the blog as they become available.
Data were collected on November 14, 2019 while the R/V Monitor was underway collecting bacteria samples in the Seekonk and Providence River estuaries. The chlorophyll concentrations were good. From north to south, average chlorophyll concentrations were as follows: Seekonk River (1.47 µg/L), Upper Providence River (0.95 µg/L), Edgewood Shoals area (0.77 µg/L), Pawtuxet River area (1.06 µg/L), and Lower Providence River area (0.96 µg/L). Overall, chlorophyll ranged between non-detectable and 4.00 µg/L with an overall average of 1.12 µg/L. The chlorophyll data from this date are presented in the map below:
R/V Monitor's Blog
On Thursday, November 14th, the crew of the R/V Monitor was out on the upper Bay collecting bacteria 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. Water column profiles and Par measurements were not done this day, as the equipment is being calibrated. Sara captained the boat while monitoring professionals Steve and Amanda collected the samples and data. It was a cold and cloudy day with no wind and glass-like waters. Today's photo features a US Coast Guard vessel observed on the Bay.
Water Column Profiles
Water column profiles were measured at five sites in the Providence River on October 24, 2019. A sixth site, Bullock Reach, was also surveyed however a malfunction with the instrument caused the data to be incomplete and unusable. The two days prior to the survey were rainy, with 0.16 inches recorded on October 22 and 0.42 inches recorded on October 23 (TF Green gauge data). Salinity stratification was observed at three sites (Pomham Rocks, Conimicut Point, and India Point Park), while the remaining two sites exhibited well-mixed conditions.
Surface salinities were highest at Pomham Rocks (29 psu), and lowest at India Point Park (25 psu). The highest bottom salinity (31 psu) was observed at Pomham Rocks and Conimicut Point, while the lowest (29 psu) was observed at Pawtuxet Cove. The warmest waters overall were observed at Pawtuxet Cove, from 15.8°C at the surface to 15.6°C at the bottom. The coolest surface waters (14.3°C) were observed at Conimicut Point, while the coolest bottom waters (15.1°C) were observed at India Point Park and Pomham Rocks.
This week, hypoxic conditions (e.g., dissolved oxygen [DO] concentrations <2.9 mg/L) were not observed at any of the sites. Surface and bottom DO ranged from 5 to 7 mg/L across all sites. Fluorescence was much lower than previous surveys on September 25, averaging 1.4 mg/m3 among all sites, with a maximum of 3.1 mg/m3 at 3.25 – 3.5 m at Conimicut Point.