Characterizing sedimentary phytopigment values directly before environmental impact in NORI, Clarion Clipperton Zone

The increased demand for metals to aid in the green technology transition has led to the development of exploratory areas for deep sea mining within the Clarion Clipperton Zone (CCZ). The seafloor of the CCZ contains nodules composed of critical metals. Sedimentary phytopigments, chlorophyll-a and phaeophytin, are indicators of labile organic matter and degraded organic matter deposits, respectively. The characterization of these pigments in the Nauru Ocean Resources Inc. (NORI) exploration zone of the CCZ is necessary to understand the deposition of organic matter to the seafloor as well as the availability of food for detritivores. We establish pre-test mining values as a baseline to determine the environmental impact of test mining. Samples were collected in August-September 2022 via multicore aboard the Island Pride. Sediment cores 0-5 centimeters in depth were separated into 1 centimeter increment subsamples. Acetone extracts were taken from each subsample for spectrofluorometric analysis. Previous baseline samples from 2020 and 2021 determined average concentrations were 0.027 +/- 0.004 ug/g chl-a; 0.049 +/- 0.005 ug/g phaeo in test mining areas. Calculations of values within the test field and outside the test field are in progress. The characterization of phytopigment concentrations within NORI allows for the comparison of these values before test mining, which occurred October-November 2022, to those immediately after test mining. This data will contribute to the documentation of deep-sea mining impact as companies attempt to harvest metals, pushing forward the movement towards green technology. 

Poster 

For more information: iaiannot@eckerd.edu

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