QUALITY ASSURANCE/QUALITY CONTROL Maryland Department of Natural Resources followed specific procedures to ensure that the Mainstem component of the Chesapeake Bay Water Quality Monitoring Program design was properly implemented and managed with sufficient accuracy, precision and detection limits. Accuracy (closeness to the true value) of collected data was controlled and assured by proper use, calibration and maintenance of both field and laboratory equipment for the measurement of physical and chemical parameters. The procedures to control and assure the accuracy of field measurements involved the calibration of field instruments, the verification of calibrations, and equipment maintenance. Most of the details of how data acquired with YSI sondes were quality assured and quality controlled are described in the process description elements in the Lineage portion of this metadata record.
Daily quality control checks, which included the running of blanks and standards, were used to control and assure laboratory accuracy. Accuracy of Chesapeake Biological Laboratory, Nutrient Analytical Services Laboratory (CBL NASL) results was also assessed through DNR's participation in the Chesapeake Bay Coordinated Split Sample Program (CSSP) a split sampling program in which five laboratories involved in Chesapeake Bay monitoring analyze the coordinated split samples. CSSP was established in June 1989 to establish a measure of comparability between sampling and analytical operations for water quality monitoring throughout the Chesapeake Bay and its tributaries. DNR followed the protocols in the Chesapeake Bay Coordinated Split Sample Program Implementation Guidelines (EPA 1991) and its revisions. Split samples were collected quarterly. Results were analyzed by appropriate statistical methods to determine if results differed significantly among labs. If a difference occurred, discussions began regarding techniques and potential methods changes to resolve discrepancies.
ADDITIONAL COMMENTS
January 2016: Silicate samples were not frozen after collection due to equipment issues. Water for both the surface and the 1.0 m samples at stations CB5.2 and CB4.3C was collected at the same depth. Pycnoclines were not evident at stations: CB5.2, CB5.1, CB4.4, CB4.3C, CB4.2C and CB4.1C. Therefore the above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of total water column depth, respectively.
February 2016: Silicate samples were not frozen after collection due to equipment issues. Scoping is a term used to describe situations when strong currents and or winds make it difficult to maintain the water quality data sonde at a depth long enough for readings to stabilize. Meter scoping was noted at stations: CB4.4, CB4.3C, CB4.2C, CB4.1C and CB3.3C. Water samples for surface and 1.0m at stations: CB4.3C, CB4.2C, CB4.1C and CB3.3C were collected at the same depth.
March 2016: At station CB2.2, water for both the below pycnocline and the bottom sample was collected from the same bottle. Meter scoping was noted at stations: CB5.2, CB5.1, CB4.4 and CB4.3C. There was no pycnocline at station CB5.2 and the above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of the total water column depth, respectively.
April 2016: Meter scoping at the bottom was logged when station CB3.1 was sampled. Surface and 1.0m water samples at stations: CB5.2, CB5.1, CB4.4, CB4.3C and CB4.2C were collected at the same depth. Due to no pycnocline, above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of the total water column depth, respectively, at the following stations: CB5.2, CB5.1, CB4.4, CB4.3C, CB4.2C, CB4.1C, CB3.3C and CB2.2.
May 2016: Station CB4.4 data sonde readings were double checked at 15.0m. Surface and 1.0m water samples at stations: CB4.3E, CB4.3W and CB4.2W were collected at the same depth. A strong tide was noted at station CB3.3C. Station CB3.3W conductivity readings were unstable at 7.0m. Attempts to post-calibrate the meter D dissolved oxygen sensor, used for sampling at station CB5.1W, were not successful.
June 2016: The first June cruse was conducted June 6-8. A squall passed through during sampling operations at station CB1.1 8-Jun-2016. The sampling array touched the bottom at 11m at station CB2.2. Similarly, the array hit bottom at station CB2.1. Absence of pycnoclines at stations: CB5.1, CB4.4 and CB4.3E necessitated collection of the above pycnocline and below pycnocline samples at 1/3 and 2/3 of total water column depth. A ship passed during sample collecting at station CB4.3C. Station CB4.1E temperature readings at 5m were double checked. Surface and 1m water samples at stations CB3.2 and CB3.1 came from water collected at the same depth.
Rough conditions June 14, at station CB5.1W, made LI-COR sampling unsafe.
The second June cruise was conducted June 27-29. Station CB5.2 sonde readings at 10m and 13m were double checked. At station CB4.3C meter scoping at the bottom was noted. Surface and 1m samples were comprised of water collected at the same depth. The above pycnocline and below pycnocline samples at station CB4.1E were collected from 1/3 and 2/3 of the total water depth, respectively. The 2m sonde readings were checked twice at station CB3.3E
July 2016: During the first July survey (July 11-13), 14m and 15m sonde readings at station CB4.4 were double checked. Meter scoping was noted at station CB4.1C. The surface and 1m samples were taken from water collected at the same depth.
August 2016: On the first survey (August 8-10), hydrogen sulfide odors were observed in bottom and below pycnocline water sampled at stations: CB4.3E, CB4.3C, CB4.2C, CB4.1E and CB4.1C. The bottom sample water at station CB3.3C had a hydrogen sulfide smell. Split samples were churned by hand when water was dispensed into sample bottles. (Normally, churning is accomplished using an electric drill). Meter scoping was noted at station CB4.4. A tanker passed while samples were collected at station CB3.2. Station CB3.2 and CB3.1 surface and 1m samples came from water collected at the same depth.
During the second cruise (August 29-31), a hydrogen sulfide odor was observed in bottom water sampled at stations CB5.1 and CB3.3C. Hydrogen sulfide odors were also noted in water samples collected at stations: CB4.3E, CB4.3C, CB4.2C, CB4.1C bottom and below pycnocline depths. Both the 0.5 m and 1.0 m water samples at stations: CB5.3, CB4.3C, CB4.3W and CB4.2W were collected at the same depth. Meter scoping was reported at stations CB4.3C, CB4.2C and CB3.3C. The air temperature reading at station CB2.2 was taken in the sun.
September 2016: Heavy storms preceded sample collection at station CB5.3. Similarly, heavy rainfall occurred before station CB5.2 was sampled. Stations: CB5.3, CB4.3W, CB4.2E, CB4.2C and CB4.2W 0.5m and 1m water samples were drawn from water collected at a single depth. Meter scoping was noted at station CB4.2C and near the bottom when station CB4.1C when water quality was measured. Absence of a pycnocline at station CB2.2 necessitated collection of the above pycnocline and below pycnocline samples at 1/3 and 2/3 of total water column depth.
October 2016: USS Zumwalt passed while sampling was conducted at station CB5.1. Coiling and kinking of a newly-deployed sampling hose were noted. The bottom and below pycnocline water samples drawn at stations: CB4.4, CB4.3E, CB4.3C, CB4.2C, CB4.1E, CB4.1C, CB3.3C, CB3.2 and CB2.2 came from the same bottle. Meter scoping was noted at station CB4.1C. Dissolved oxygen reading at station CB3.1 were double checked.
November 2016: Split samples were churned by hand when water was dispensed into sample bottles. Station CB3.1 0.5m and AP water samples were drawn from water collected in a single bottle. Pycnocline thresholds were not met at stations: CB5.3, CB5.2, CB5.1, CB4.4, CB4.3C, CB4.2C and CB2.2. Therefore, the above pycnocline and below pycnocline samples, for each station, were collected from 1/3 and 2/3 of the total water depths, respectively.
December 2016: Stations CB5.2 and CB5.1 surface samples were collected at 1m depths. Pycnoclines did not exist at stations: CB5.2, CB5.1, CB4.4, CB4.3C, CB4.2C, CB4.1C and CB3.3C. Therefore, above pycnocline and below pycnocline samples at each station were collected from 1/3 and 2/3 of the total water depth. Surface conductivity readings changed between the beginning and the end of the hydrocasts at station CB3.1. pH readings took more than five minutes to stabilize at 9.3m at station CB1.1.