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Abstract. Late Cretaceous clays exposed at sites located on the north shore of Long Island, New York, USA, were sampled to explore questions about how contemporary factors and processes interact with ancient geological materials that are often assumed to not be biologically active. Chemically and biologically catalyzed weathering processes have produced multi-colored clays belonging to the kaolin group with inclusions of hematite, limonite, and pyrite nodules. We sampled exposed clays at three sites to address three questions: (1) do these exposed clays support significant amounts of microbial biomass and activity, i.e., are they alive? (2) Do these clays support significant nitrogen (N) cycle activity? (3) Are these clays a potential non-anthropogenic source of reactive N in the contemporary landscape? Samples were analyzed for total carbon (C) and N content, microbial biomass C and N content, microbial respiration, organic matter (OM) content, potential net N mineralization and nitrification, soil nitrate (NO3-) and ammonium (NH4+) content, and denitrification potential. Results strongly support the idea that ancient geologic materials play a role in contemporary N and C cycling in the Critical Zone. Respiration (average 4.098 µg C g−1d−1) was detectable in all samples and was strongly correlated to OM, indicating a living microbial community on the clays. There was evidence of an active N cycle. Higher levels of denitrification potential (average 1.376 µg N g−1 d−1) compared to both potential net nitrification (average 0.061 µg N g−1 d−1) and potential net N mineralization (average 0.144 µg N g−1 d−1) indicate that these clays act more as a sink rather than as a source of reactive N in the landscape. 

The knowledge of unsustainable human and Earth system interactions is widespread, especially in light of systemic environmental injustices. Systems science has enabled complex and rigorous understandings of human and Earth system dynamics, particularly relating to pollution of Earth’s land, water, air, and organisms. Given that many of these systems are not functioning sustainably or optimally, how might this field enable both rigorous understanding of the issues and experiments aimed at alternative outcomes? Here, we put forth a novel, multiscale systems science approach with three steps: (1) understanding the systemic issues at hand, (2) identifying systemic interventions, and (3) applying experiments to study the efficacy of such interventions. We illustrate this framework through the ubiquitous and yet frequently underrecognized issue of soil lead (Pb). First, we describe the systemic interactions of humans and soil Pb at micro-, meso-, and macroscales in time and space. We then discuss interventions for mitigating soil Pb exposure at each scale. Finally, we provide examples of applied and participatory experiments to mitigate exposure at different scales currently being conducted in New York City, NY, USA. We put forth this framework to be flexibly applied to contamination issues in other regions and to other pressing environmental issues of our time.