Field Notes

Hill Slough: 2024-01-18 16:35:00 (DOY 18)
Author: Daphne Szutu
Others: Arman

Summary: Near low tide, swapped 7500 for calibration, gaps in mux data--fixed maybe, removed EXO for calibration--fish, roe, mysids

2024-01-18
Hill Slough

Arman and I arrived at 16:35 PST. It was cool, mostly overcast, and near low tide. This site is always scenic in the wintertime because we're here near sunset. The channel staff gauge read 3.2ft at 17:15 PST.

Arman cleaned flux and rad sensors and swapped the 7500 for calibration: sn 0418 came off and sn 1594 went on. I uploaded a new config file and updated the pressure coefficients. The 7550 software froze a few times while I was trying the update the pressure coefficients. I think my holding the laptop and moving back and forth between the 7550 and the met box meant the USB connection was getting loose. Eventually I got the pressure coefficients updated and saved. The eddy clock looked ok. I had trouble ejecting the USB from the 7550 software and the USB LED had a slow blink. We pulled the USB and reset the box. The GHG data looked fine and the new USB mounted fine. I confirmed that the 7500 was OK and the 7700 was connected w/o error. Maybe just stick with ejecting the USB using the Eject button on the 7550.

0418 dirty read: 415ppm Co2, 595mmol/m3 H2O, 13.4C, 102.0kPa, 98SS
0418 clean read: 434ppm Co2, 476mmol/m3 H2O, 13.1C, 102.0kPa, 104SS
1594 fresh read: 439ppm CO2, 462mmol/m3 H2O, 12.7C, 102.0kPa, 98SS
The 7700 read: 2.18ppm CH4, 53RSSI – 82 after cleaning

The reservoir was 65% full; Arman refilled it.

I downloaded met, cam, and USB GHG data. Most sensors on the mux had gaps or spikes, such as AirT/RH, PARin/out and the 4-way radiometer. I unplugged and replugged all of the mux blocks. None seemed particularly loose, but hopefully that will solve the problem. I forgot to check the wiring for the blocks connecting the datalogger and mux.

I showed Arman how to take the porewater samples using the 3-way valve and syringe. The very first pull of water seemed to trickle back down the tubing quickly, but maybe we didn't maintain enough suction on the syringe or the valve was not closed completely. We measured the first two pulls and the second pull was fresher and cooler. We measured the surface conductivity at the channel since there wasn't enough water under the tower.

Sample, Temperature-compensated conductivity, Temperature
Porewater_flush, 9.42 mS, 12.7 degC
Porewater, 9.15 mS, 11.6 degC
Surface, 5.33 mS, 11.1 degC

At the channel, we pulled the EXO for calibration. Two fish fell out when we pulled it up, and there was another pile of fish roe on the sensors. I rinsed off the roe and random mysids. The brush had stopped over the pH sensor again so I will make sure to test this in the lab before we deploy it again. I disconnected the EXO power and tied up the sensor cable underneath the datalogger enclosure.
Sensors removed:
sn 22C103416 EXO2
sn 22E106072 Turbidity
sn 22E100649 fDOM
sn 23D104030 Conductivity/Temperature
sn 22D102641 pH/ORP

Arman cleaned the channel staff gauge with the telescoping scrubby pad. It was hard to see the big number at the top, but I think it's the bottom half of 4.

We left at 17:15 PST right at sunset.

2 photos found

20240118HS_Arman.jpg ( 2024-01-18 17:13:45 ) Full size: 1920x1440
Arman using the telescoping scrubber to clean the staff gauge by the Hill Slough channel