Dataset: Water chemistry

Samples were collected in a perimeter of ~1 km offshore of the discharge channel of Carlsbad Desalination Plant, Carlsbad Beach, California (33°08'18.9"N 117°20'21.3"W).

Samples were collected in four trips:
Pre-discharge: Dec 2nd-4th 2014 and Sep 21st-24th 2015.
Post-discharge: May 9th-12th 2016 and Nov 8th-11th 2016

Transect lines were deployed going from the discharge channel (Outflow) and the Intake to 1000 m offshore. Sampling was done every 25 m until 200 m offshore, then at 400, 600, 800 and 1000 m (“stations”). The “Parallel” transect ran continuous parallel to the beach ~200 m offshore and samples stations were deployed every ~100 m. Station 1 is the southern-most sampling point (south of discharge channel). At each station surface (~1 m depth) and bottom water samples were taken and a sediment sample.

The benthic surveys were done continuously at the first 200 m offshore if water conditions allowed. At station 400, 600, 800 and 1000 and on the parallel stations, 10 1x1m quadrates were deployed.

Water was filtered and preserved within 4 hours of collection

Temperature: Temperature was measured with a YSI 85 probe immediately after collection.

pH: pH was measured with a handheld pH probe

Salinity: Water samples were analyzed on a Guideline Portasal instrument.

Chl A: 250 ml seawater was pumped through a GFF filter and the filters were kept in the dark and frozen until analysis. Filters were treated with 90% acetone for 24 hours and analyzed on a TD-700 fluorometer.

Nutrients: Samples were filtered and immediately frozen. Samples were analyzed using a flow injection nutrient auto-analyzer (Lachat). Total nitrogen is determined as nitrate following oxidation with persulphate and UV radiation and total dissolved phosphorus as phosphate following UV radiation.

DOC: 50 ml filtered water was acidified with concentrated HCl. Samples were analyzed on a Shimadzu TOC-V CHS