Rano Raraku geochemical data

A geochemical survey of the water, suspended particulate matter, sediments and soil of the Rano Raraku crater lake basin in Rapa Nui (Easter Island) was performed in order to assess if the lake water could have been a viable fresh water source for early inhabitants, as well as better understanding past interactions between humans and environmental conditions as archived in lake sediments. At the time of sampling in September 2017, lake maximum depth was 1.5 m. The lake level has substantially declined in the subsequent years, with the lake drying almost completely in January 2018. The lake is currently characterized by highly anoxic conditions, with a predominance of ammonium ions on nitrates, a high concentration of organic carbon in the water-sediment interface and reducing conditions of the lake, as evidenced by Mn/Fe and Cr/V ratios. At the time of sampling, water pH was 7.8.