Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

This dataset includes water chemistry results from samples collected at the surface and bottom water offshore of the discharge channel of Carlsbad Desalination Plant, Carlsbad Beach, California.

Related datasets:
Benthic macrofaunal abundance
Macrofauna species distribution
Phytoplankton cell count
Sediment fauna and plastic
Sediment grain size

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

BCO-DMO Processing:

- added conventional header with dataset name, PI name, version date
- renamed parameters to BCO-DMO standard
- added year column
- sorted data by year, site, direction, station, depth

Version 1: 2015-08-03
Version 2: 2015-08-11 (added lat_site/lon_site for mapping purposes)
Version 3: 2016-09-21 (added 2015 data)
Version 4: 2017-09-22 (revised 2014 data and added 2016 data)

Description from NSF award abstract:
Desalination of seawater accounts for a worldwide water production of about 70 million cubic meters per day. Despite the many benefits the technology has to offer, there are concerns over potential negative impacts on the environment. A key issue that has not been thoroughly investigated is the impact of effluent discharge on coastal marine ecosystems. This project will provide quantitative scientific assessment of the potential impacts of effluent discharge on coastal ecosystems in California and assess how such data influences public perception and public policy. The team of social and natural scientists has experience related to coastal pollution, California coastal ecology, marine biogeochemistry, toxicology, environmental policy and economics, water policy and management, and utility-stakeholder communications. Established relations with desalination facilities in California will ensure an integrative framework for research on the human and environmental aspects related to the increasing abundance of desalination facilities along the California coast, and contribute to both securing freshwater resources and sustaining productive and healthy coastal communities and coastal environments.

The objectives of this project are to (1) determine how effluent discharges from facilities for seawater desalination by reverse osmosis affect key organisms of the California coastal ecosystem with implications for ecosystem structure and function, (2) describe the spatial extent of the effect for different discharge schemes, and (3) evaluate how results from this and similar environmental impact studies influence public perception and decision making regarding desalination plant construction and operation. The project will combine in situ field chemical and biological measurements, controlled laboratory experiments, and assessments of how people and organizations interpret and use this data for making environmentally sound and sustainable decisions. Field studies will be performed at three different desalination plants to identify and quantify the possible effects of stressors associated with effluent discharge on local biota. Observed effects will be validated through controlled laboratory bioassay experiments. The scientific results will be communicated to the general public and decision makers to assess how scientific data is used by different stakeholders.

This project is supported under NSF's Coastal SEES (Science, Engineering and Education for Sustainability) program.