Research cruise on ocean acidification and microplastics in the North Pacific

An international team of scientists, involving ICREA research professor at ICTA-UAB Patrizia Ziveri, conducted a month-long research cruise from Hawaii to Alaska aboard the University of Hawaii's R/V Kilo Moana.

During the cruise they sampled sites from sub-tropical gyres to sub-polar waters, conducting experiments on sediment and water from different ocean depths. They chose this route because these are among the most acidic waters in the world oceans.

In particular the members of the groups in charge of the calcifying plankton studies were Dr. Patrizia Ziveri (ICTA-UAB) and Dr. James Rae (University of Sant Andrews).  As certain shelled plankton, called pteropods, die and sink to the ocean floor, they become part of the sediment. However, with a more acidic ocean, the shells are dissolving well before they reach the ocean floor. Analyzing this data along the cruise transect route provided an opportunity to characterize a large portion of the ocean. 

Dr. Ziveri collected also samples to characterize the distribution of plastic debris and micro plastic in this transect crossing the 'Pacific garbage patch'. This is one of most polluted large open ocean areas with regard to plastic pollution.  The team also aimed to understand the fate of plastic in the ocean sampling a different water depth and the deep sediment.

Specifically, the team, led by Dr. Will Berelson from the University of Southern California and Dr. Jess Adkins from California Institute of Technology (CalTech), studied how the deep ocean neutralizes increased amounts of carbon dioxide (CO2) using the mineral calcium carbonate. As the ocean absorbs more CO2 from the atmosphere, it causes a fundamental change in the chemistry of the ocean.  One change is that the ocean uses calcium carbonate to absorb CO2, essentially dissolving the mineral and leaving fewer calcium carbonate molecules available for marine organisms - such as coral, plankton, and shellfish - to use to build structures and shells. 

The research team conducted experiments on the rate at which calcium carbonate dissolves with location-specific variables such as water temperature, salinity, nutrients, and depth and also collected sediment and plankton samples.