Ecosystems Impact of Air Pollution

This page last reviewed November 20, 2014

Acid Deposition

Scientific evidence in other parts of the world has shown that atmospheric deposition of sulfur and nitrogen compounds can cause harm to the environment and, thus, may present a threat to California's ecosystems and the health of its citizens. To adequately address this serious concern, the causes and effects of acid deposition in California were studied in two comprehensive State-funded monitoring and research programs.

Lake Tahoe Atmospheric Deposition Study - LTADS (ARB, TRPA, Lahontan, TRG, UCD, UCB)

Lake Tahoe is a beautiful lake ringed by mountains; it is also the second deepest lake in the U.S. and the tenth deepest in the world. This unique alpine lake is world-renowned for its rich blue color. The unique color of the lake is due to its high altitude and pristine water clarity. Objects more than 100 feet deep could be seen through the water. The water clarity is so good because 40 percent of the precipitation within the Lake Tahoe watershed falls directly on the lake; furthermore, the remaining precipitation in the Basin drains through granitic soil, which is relatively nutrient sterile and filters material. However, the water clarity of this once pristine lake, with 63 tributaries draining into and only one draining out of the lake, has been declining. Between the mid-1960s and the mid-1990s, the water clarity has decreased from 100 feet to 65 feet, a decrease averaging over one foot per year! Data for recent years suggest an improvement but additional study is needed to clearly understand the factors impacting water clarity and to ensure environmental thresholds are attained. Increasing inputs of biologically accessible forms of phosphorus (P) and nitrogen (N) cause algal growth in the lake, which is a major factor in the decline of water clarity. The focus of this study is better quantification of the direct atmospheric deposition of nutrients (P & N) and particulate matter (PM). The nutrients can be deposited as gases, particles, or soluble ions in rain and snow. The study will also address the relative contribution of local (within basin) and regional (transport into the basin) sources of nutrients and PM.

Climate Change Program (California Energy Commission ).

On October 13, 2001, Governor Davis signed Senate Bill 527 (SB 527) into law. This bill requires the Commission to provide guidance to the Registry on a number of issues, including developing GHG emissions protocols, qualifying third-party organizations to provide technical assistance, and qualifying third-party organizations to provide certification of emissions baselines and inventories.

As an initial step in fulfilling these requirements, the Commission will hold this public consultation meeting to discuss the implementation of SB 527. At the meeting, the Commission staff and others will present the requirements of SB 527, a Registry overview, an overview of existing GHG protocols and programs, key activities to be undertaken to implement SB 527, and the proposed timetable for those activities. During the meeting, participants will also have opportunities to discuss roles of the various stakeholders, and key topics and issues in developing the guidance.


California's complex Ecosystems interact with emissions related to human activity and substantially Impact Air Pollution photochemistry. Flora, desert species, Oaks, and Pines emit substantial amounts of highly reactive organic hydrocarbons. There is a complex and non-linear relationship between human activity nitrogen oxides emissions and these Biogenic emissions. This relationship is critical to the determine how we advise decision-makers about how much control of human activity nitrogen oxides California should require. It is thus critical to provide accurate estimates of Biogenic emissions. The mission of Biogenic Working Group is to develop reliable simulations for these emissions.


Certain Biogenic emissions also produce Aerosols. We believe that a significant amount of the aerosol load in California is in the form of these Secondary Organic Aerosols of Biogenic Origin. To devise an aerosol control program we need to determine the effect of emissions from human activity and land disturbances on the aerosol load in comparison to the Biogenic particulate matter load. Further, emissions from human activity may interact with Biogenic emissions to magnify negative health effects. Our research program in this area is nascent. We have begun a new project with UC Berkeley to study this problem.


Biogenic emissions include aeroallergens, such as pollens and mold spores. In California there is a broad range of grasses, weeds, and trees, both native and introduced, that use airborne pollination to reproduce. Similarly molds, growing both indoors and outdoors, produce spores which often have allergenic properties. Such biogenic emissions may interact with air pollution from human or geologic activity to cause health problems in respiratory compromised people, especially asthma sufferers who also have allergic symptoms. The following web sites are provided as links for more information about aeroallergens.

En Espanol

Flora in California often germinate in high heat natural fires. Fire is a necessary fact of Natural and Agricultural Ecosystems in California. These Biogenic Aerosols and Fire Emissions form health effects aerosols and reduce visibility. United States Congress and California legislature have required us to devise programs that protect wild lands visibility. Cal/EPA, California Department of Forestry and United States Forest Service and others have significant research programs in fire emission estimation and simulation. Our visibility research program is however nascent.


As it is clear, interaction of Ecosystems with Air Pollution includes complex emission processes, there are also complex deposition and removal processes. We have explored ozone deposition in a complex study in San Joaquin Valley. Dry deposition of aerosols and gases on the vast surfaces of the leaves and needles of California flora are otherwise largely unexplored. After senescence, detritus of leaves and needles decomposing emit organic gases to the atmosphere that are largely unexplored as well. Rain creates wet deposition events taking atmospheric gases as well as deposited gases and aerosols on leaves and needles into the water compartment. These wet deposition events are largely unexplored. These are Net Effects issues and our research program is nascent in this area. Accumulated information on effects of vegetation on trees is however available.


Biogenic Day on July 11th, 2001
- Three presentations on ecosystem effects from Dr. Arthur Winer, Dr. Allen Goldstein, and Dr. John Karlik.

3th and 14th, 2000  (PDF - 61KB )

Biogenic Research Symposium on December 9th to 10th, 1999
(PDF - 34KB )

For further information, please contact: Ash Lashgari at (916) 323-1506.