There are several modes of transport from land to the ocean, one of which is the atmospheric deposition of dust and particles. Atmospheric deposition has been widely recognized as a source of both helpful nutrients and harmful pollutants to coastal ecosystems, particularly in the case of fine aerosols and dust particles, which can be transported over very long distances. Atmospheric particles may include nitrogen and iron, sulfur compounds, mercury, pesticides, phosphate, trace metals and other toxic compounds.

Dr. Adina Paytan's research on atmospheric deposition takes place at several sites throughout the world, one of which is Elkhorn Slough, which provides a pristine area to sample particulates found in the atmosphere. Several types of samplers – of rainwater, aerosols, and mercury deposition – take collections continuously, and samples are analyzed weekly to evaluate the load of pollutants coming from the air into the slough and neighboring Monterey Bay. A meteorological station provides the necessary weather data to be factored in.

"Atmospheric deposition is a whole mixture of things – it could bring important nutrients or toxic components, or viruses and fungi"

In addition to Elkhorn Slough, Adina's lab supports several sites around the globe where atmospheric deposition is being studied, each of which provides unique conditions: one in the Red Sea, one in Bermuda, and one in China. "There’s a lot of concern about the impact of Asian dust on coastal ecosystems," says Adina. "It passes through big industrial sites, and we’ve found that pollutants transported in the air, particularly if rich in copper or other toxic heavy metals, can actually get to concentrations that are negatively impacting phytoplankton." These pollutants may contribute to harmful health and environmental impacts such as eutrophication, contaminated fish and harmful algal blooms. At Elkhorn Slough there are samplers that monitor mercury, which accumulates in the ecosystem and moves up the food chain.

"These particles have a significant effect, particularly the more offshore you go, because that's the only external source of new matter into the ocean," says Adina. "It’s a delicate balance between positive and negative, which varies according to location, which is why we have sites at such a wide array of settings." Adina's research is providing a baseline, to be used to calculate and predict change in a future that contains climate change, increased population and industrialization.