Home Archived April 24, 2019

  California Water Science Center

Carbon Processes

The Carbon Processes taking place

GreenHouse Gasses

GreenHouse Gasses


Mercury in the process

The Research and Development

The Twitchell Island pilot project has shown that it is highly feasible to use managed wetlands to sequester carbon and reduce subsidence. Additional scientific work is necessary to learn how to maximize growth rates, verify greenhouse gas benefits over several years and minimize any potential adverse environmental impacts.


Gaining the best bang for the buck

We know that these carbon capture systems are effective, but there are several questions that need to be answered:

  • Can we determine why some portions of the Twitchell Island wetlands are capturing carbon twice as fast as other areas?
  • Can conditions be modified to increase carbon capture?
  • Would carbon-capture farms perform the same if they were located in other parts of the Bay-Delta Estuary?
  • How will climate change affect carbon farms? For example, what will happen if sea levels rise and nutrient loads, water temperatures and salinity increase?


Verification of greenhouse gas benefits

The Twitchell Island research has documented significant sequestration, or capture, of CO2. But wetlands can be emitters of methane and nitrous oxide (N2O), two other greenhouse gases. Preliminary measurements of methane at Twitchell vary widely, and more monitoring is needed. Researchers have not measured for N2O, a far worse greenhouse gas. Greenhouse gas impacts also need to be precisely measured at adjacent farmland and for different land-use types in the Delta. Specific questions that need to be answered:

  • What are the total greenhouse-gas emissions, including methane and N2O? How do these emissions evolve as the carbon-capture farm grows over years or decades?
  • What are the greenhouse gas emissions for Delta farmlands and other typical land uses?


Do no harm

Large-scale efforts to manage the environment have a decidedly mixed record of success. Our research will address two major areas of concern: production of methyl mercury and transport offsite, and the addition of dissolved organic carbon to Delta waters that are used as drinking water sources. Specific questions about the carbon-capture farms which need to be answered are:

  • Do farm conditions which capture the most carbon also produce methylmercury, and if so, how much, and can the process be managed to mitigate this production?
  • How does methylmercury production and transport in carbon-capture farms compare to production by Delta farms and other typical Delta land uses?
  • What levels of mercury are found in the aquatic and terrestrial plants and animals living in the carbon-capture farms that can be attributed solely to methylmercury being produced in the farm system?
  • What amounts and types of dissolved organic carbon are produced in the carbon-capture farm?
  • How is the dissolved organic carbon related to conditions driving sequestration and mercury methylation?
  • Is the dissolved organic carbon coming off the farms important for the Delta food web and/or of concern to drinking water suppliers?
  • Can the carbon-capture farm be managed to control any adverse effects linked to dissolved organic carbon and methylmercury production?

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Page Last Modified: Thursday, 29-Dec-2016 22:57:31 EST