What are we looking for? Toxins introduced into the environment vary with different land uses. A very brief list of examples includes pesticides from agriculture, heavy metals from urban utilities, and hydrocarbons like petroleum from military projects. In the absence of comprehensive pollutant monitoring programs, understanding how land use history affects current pollution risks can help inform management and restoration strategies.

How do we get that information? In this project, we integrated maps spanning 200 years (1825-2023) to trace land use changes in ​​Pu‘uloa on Oʻahu, Hawai‘i to assist in developing containment risk profiles. We observed a marked increase in agricultural land use following the United States annexation of Hawaiʻi in the late 1890s, followed by a decrease before World War I due to military activities. Post-World War II, there was a resurgence in agriculture. Since Statehood in the late 1960s agricultural land significantly decreased due to urbanization. There are at least 28 documented chemicals, with arsenic emerging as an important risk, that are present in the area, and many of the contaminated spots are currently located in residential or commercial zones.