Field Notes

<--2022-11-03 10:00:00 | 2022-11-18 08:45:00-->

Gilbert Tract: 2022-11-08 07:15:00 (DOY 312)
Author: Ariane Arias-Ortiz
Others: Marc, James, Daphne, Dennis, Robert, Koong, Carlos and others

Summary: 24h tidal cycle sampling

The goal of this tidal sampling was to collect a high resolution (every 1 hour) physico-chemical snapshot of surface waters throughout a full tidal cycle during the wet season (as a continuation of the 24h tidal cycle sampling during the growing season). The sampling location was the same, Gilbert Tract breach between the ADCP and EXO2 YSI. Collected samples in this round will be analyzed for dissolved organic/inorganic carbon, dissolved gas concentrations, anions, MeHg, and nutrients (DIN and DIP).

It was a cold (47-55 F) rainy morning, with intermittent showers in the afternoon and evening. Clear sky at night. There was a moderate breeze during periods of rain. Water temperatures were about 13 C and there were no mosquitoes this time.

Marc Olds (Hydrofocus), James Hada (USGS), and I arrived at the site at 7.15 am and drove to the Gilbert breach to drop off the jonboat. Marc stayed at the breach and started unloading his truck. I unloaded my car and helped James to deploy one of the USGS EXO's at Marsh Creek, right before the bridge at the western edge of the Emerson's parcel. The road at Emerson was very muddy, there is less gravel on the ground, and I had to park my car and drive with James in his pickup truck. We deployed the EXO and returned to the Gilbert tract breach at around 8.30 am. Daphne and Dennis had arrived and with Marc, they had set up the canopies, and tables, and unloaded all the coolers and boxes with sampling supplies. Marc and I lowered the boat into the water and paddled to the opposite bank to span the rope between the two fence posts installed during May's tidal cycle sampling campaign. It was pretty easy to reach the opposite bank with paddles. The wind was low and we were near slack water at low tide. We anchored the jonboat to the 100 ft spanning rope using carabiners.
Daphne and James checked on the UCSC EXO and realized it hadn't recorded any data since we deployed it last Thursday. The configuration was set to measure 1 min bursts every 15 min, but for some reason, it had changed to 0 min bursts. We tested a new configuration without the burst mode for a few minutes and confirmed there wasn't any problem and data was being stored. Finally, we changed the configuration to 1 measurement every 15 min without the burst mode and re-deployed the EXO, hoping it would continue to record data throughout the sampling campaign. The EXO was deployed at 34 cm (from the top of the channel post to the top of the housing post), which is equivalent to about 1.15 m depth from the top of the channel post. The rear end of the housing was sitting on the channel bank while the front end was in the water at about 20-30 cm from the bank slope. We started sampling at 9.30 am and the first MeHg composite sample was skipped and collected at the end of the graveyard shift as an additional sampling event at 9 am on Nov, 9th.

Shifts:
We organized four shifts (6 hr each) formed by UCB and Hydrofocus personnel. USGS James and Kail participated in the morning and graveyard shifts, respectively.

Morning crew
8:00-15:00
sampling starts: 9:00
sampling ends: 14:00

Afternoon crew
14:00- 21:00
sampling starts: 15:00
sampling ends: 20:00

Evening crew
20:00-3:00
sampling starts: 21:00
sampling ends: 2:00

Graveyard shift
2:00-9:00
sampling starts: 3:00
sampling ends: 8:00

We had 3 tables, coolers for UCB and Hydrofocus (each group brought their own), and two canopies (one from the lab). A link to detailed SOP's for sample collection and analysis is provided here:
https://berkeley.box.com/s/pqo7vop4yv4hpzaak0fwbr66zc699n79

We conducted a sampling event every hour, and two boat trips were required to sample all of the analytes. On the first boat trip, two participants collected all the syringe samples at the center of the channel and recorded physico-chemical parameters (pH, water temp, specific conductance, dissolved oxygen, and flow velocity) with a handheld YSI probe and a manual flow meter. These measurements and except for the very first one, happened at the ~o'clock hour.
The second boat trip was conducted at around 20-30 min past the hour to sample Hg and MeHg with the depth-integrated sampler. In this case, 5 locations were sampled across the channel-spanning transect. Sampling stations were marked with yellow electrical tape on the rope directly. Three people were required to be on the boat for Hg and MeHg sampling (dirty hands, clean hands, and a person pulling the boat to reach the sampling stations). The 4rth team member remained on shore filtering and processing the syringe samples and getting all the supplies and bottles labeled before the Hg/MeHg churn arrived on shore.

The sampling campaign went well and we could do the 24 sampling events. Having 4 people per shift worked well. Overlap between shifts was necessary for the new team getting the workflow going. Robert stayed a few hours into the evening shift to help train all the Hydrofocus team members. The night shift was smooth, we saw the international space station overpassing and finished the last sampling event at around 9.40 am as we had to collect the MeHg sample that was skipped during the morning shift. During the last sampling event, we removed the channel spanning rope but left the fence posts installed in case the tidal cycle sampling needs to happen again (Hydrofocus was interested). Like last time, Waterhyacinth and some plant material were floating in and out of the channel with the tide and getting stuck on the rope throughout the tidal cycle sampling.

Marc arrived at around 8 am to help dismantle the working station. We loaded the sampling material, samples, and supplies onto the trucks and checked on the EXO again to confirm it had recorded data throughout the tidal cycle sampling. All was good (whew), we downloaded data, removed our fDOM sensor, and left the UCSC sensor installed. USGS was waiting for our fDOM sensor to ship their EXO + sensors back to YSI for inspection. Carlos downloaded ADCP data before leaving. We left the site at around 11 am, on Nov 9th. Marc stayed for a bit longer organizing Hydrofocus truck.

12 photos found

20221108GT_logsheet.jpg ( 2022-11-09 08:48:48 ) Full size: 1440x1920
Water quality parameters log sheet taken with every tidal cycle discrete sampling event

20221109GT_channel_upstream.jpg ( 2022-11-09 07:04:39 ) Full size: 1920x1440
View of the channel facing upstream of the Little Dutch Slough breach

20221109GT_syringe_sampling.jpg ( 2022-11-09 07:04:55 ) Full size: 1920x1440
Carlos is sampling at the center of the channel using a syringe-stopcock-tubing assembly

20221109GT_sunrise.jpg ( 2022-11-09 07:04:50 ) Full size: 1920x1440
Sunrise at little Dutch Slough breach, photo view is downstream, facing the booms at the channel mouth

gilberttract_2022_11_07_161406.jpg ( 2022-11-07 16:19:54 ) Full size: 1296x960
Black birds

gilberttract_2022_11_07_164405.jpg ( 2022-11-07 16:49:44 ) Full size: 1296x960
Starling

gilberttract_2022_11_08_161405.jpg ( 2022-11-08 16:19:50 ) Full size: 1296x960
Grackles

gilberttract_2022_11_09_161405.jpg ( 2022-11-09 16:19:44 ) Full size: 1296x960
Grackles

20221108GT_Boat.jpg ( 2022-11-08 14:24:19 ) Full size: 1920x1440
Boat started to capsize as people were stepping in, dumping Koong and Robert into the water

20221108GT_Channel.jpg ( 2022-11-08 14:20:22 ) Full size: 1920x1440
Turned out to be a beautiful day for the 24hr tidal sampling

20221108GT_WaterSamples.jpg ( 2022-11-08 14:13:15 ) Full size: 1440x1920
Robert, Koong, and Ari taking water samples and measuring flow during the 24hr tidal campaign

20221108GT_WaterSamples2.jpg ( 2022-11-08 14:22:53 ) Full size: 1920x1440
Robert, Koong, and Ari navigating the boat back to the southern bank during the 24hr tidal sampling campaign