Week of April 4 – April 10, 2021
Surface Mapping
Data
were collected on April 7, 2021 while the R/V Monitor was underway collecting nutrient
samples in the Providence River estuary. The chlorophyll concentrations were
good in the areas surveyed. From north to south, average chlorophyll
concentrations were as follows: Upper Providence River (2.04 µg/L), Edgewood
Shoals area (2.27 µg/L), Pawtuxet River area (1.61 µg/L), and Lower Providence
River (1.89 µg/L). Overall, chlorophyll ranged between 0.30 µg/L and 3.70 µg/L
with an overall average of 1.95 µg/L. The chlorophyll data from this date are
presented in the map below:
Week of March 28 – April 3, 2021
Water Column Clarity
Water clarity was measured at four locations in the Providence and Seekonk Rivers on March 31, 2021. Precipitation in the five days prior to sampling totaled 1.53 inches, with a majority of the rainfall (1.47 inches) occurring on March 28. Overall, water clarity increased from the previous survey. Secchi depth averaged 2.4 meters, compared to 2.2 meters on March 24, 2021. The lowest clarity (1.9 meters) was measured at Point St. Bridge, while the greatest clarity (3.1 meters) was measured at Conimicut Point. Generally, water clarity increased along a down-bay gradient.
Week of March 28 - April 3, 2021
Fixed Site Network
Phillipsdale Landing
Sondes were changed out for routine maintenance this week mid-morning on March 30. Water quality at Phillipsdale was good this week. Substantial rainfall of 2.77 inches was recorded at TF Green; the majority of this rain (1.47 inches) fell in a single day, March 28. Blackstone River flows increased following this rain, though overall remain at or below average for this time of year. Salinity at the Phillipsdale surface averaged 7.7 ppt and ranged from 1.0 ppt to 20.7 ppt. Bottom salinity averaged 16.4 ppt and ranged from 2.4 ppt to 28.8 ppt. Surface temperatures were similar this week to last, averaging 10.1°C and ranging from 7.5°C to 12.5°C. Bottom waters continued to warm slightly, averaging 9.2°C and ranging from 7.4°C to 12.3°C.
Dissolved oxygen (DO) was high at both depths, typical for this time of year, and well above the hypoxia threshold (2.9 mg/L). Surface DO averaged 10.9 mg/L, with a minimum of 9.4 mg/L, and bottom DO averaged 10.4 mg/L, with a minimum of 9.1 mg/L. Chlorophyll concentrations generally remain low, with isolated high values, averaging 6.4 ug/L at the surface and 15.2 ug/L at the bottom. Maximum surface chlorophyll concentrations reached 67.3 ug/L, measured on March 29. Please note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and dissolved oxygen at this location; chlorophyll readings could also be impacted by suspended matter/particulates.
Bullock Reach
Bullock Reach sondes are expected to be deployed in May 2021.
Week of March 21 – 27, 2021
Water Column Clarity
Water clarity was measured at eight locations in the Providence and Seekonk Rivers on March 24, 2021. Trace amounts of precipitation were recorded in the five days prior to the survey. Overall, water clarity decreased from the previous survey. Secchi depth averaged 2.23 meters, compared to 2.56 meters on March 17, 2021. The lowest clarity (1.90 meters) was measured at Pomham Rocks, while the greatest clarity (2.70 meters) was measured at Edgewood Yacht Club and Edgewood Shoal. Generally, water clarity increased along a gradient from north to south.
Week of March 21 - 27, 2021
Fixed Site Network
Phillipsdale Landing
Water quality at Phillipsdale was good this week. Light rain was recorded at TF Green, a total of 0.21 inches over March 24-26. Blackstone River flows declined all week. Salinity at the Phillipsdale surface averaged 4.6 ppt and ranged from 1.2 ppt to 17.9 ppt. Bottom salinity averaged 19.4 ppt and ranged from 2.7 ppt to 28.6 ppt. Surface and bottom water temperatures warmed slightly this week, averaging 9.9°C and 7.1°C, respectively. Surface temperatures ranged from 5.9°C to 13.0°C, while bottom temperatures ranged from 4.6°C to 11.1°C.
Dissolved oxygen (DO) was high at both depths, typical for this time of year, and well above the hypoxia threshold (2.9 mg/L). Surface DO averaged 12.1 mg/L, with a minimum of 9.7 mg/L, and bottom DO averaged 10.7 mg/L, with a minimum of 8.5 mg/L. Chlorophyll concentrations declined from the previous week, averaging 3.9 ug/L at the surface and 5.0 ug/L at the bottom. Maximum surface chlorophyll concentrations reached 40.2 ug/L, measured on March 21. Please note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and dissolved oxygen at this location; chlorophyll readings are also frequently impacted by suspended particulates.
Bullock Reach
Bullock Reach sondes are expected to be deployed in May 2021.
