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Abstract. Biogeochemistry has an important role to play in manyenvironmental issues of current concern related to global change and air,water, and soil quality. However, reliable predictions and tangibleimplementation of solutions, offered by biogeochemistry, will need furtherintegration of disciplines. Here, we refocus on how further developing andstrengthening ties between biology, geology, chemistry, and social scienceswill advance biogeochemistry through (1) better incorporation of mechanisms,including contemporary evolutionary adaptation, to predict changingbiogeochemical cycles, and (2) implementing new and developing insights fromsocial sciences to better understand how sustainable and equitable responsesby society are achieved. The challenges for biogeochemists in the 21stcentury are formidable and will require both the capacity to respond fast topressing issues (e.g., catastrophic weather events and pandemics) andintense collaboration with government officials, the public, andinternationally funded programs. Keys to success will be the degree to whichbiogeochemistry can make biogeochemical knowledge more available to policymakers and educators about predicting future changes in the biosphere, ontimescales from seasons to centuries, in response to climate change andother anthropogenic impacts. Biogeochemistry also has a place infacilitating sustainable and equitable responses by society. 

This study evaluates rates and pathways of methane (CH₄) oxidation and uptake using¹⁴C‐based tracer experiments throughout the oxic and anoxic waters of ferruginous Lake Matano. Methane oxidation rates in Lake Matano are moderate (0.36 nmol L⁻¹ day⁻¹to 117 μmol L⁻¹ day⁻¹) compared to other lakes, but are sufficiently high to preclude strong CH₄fluxes to the atmosphere. In addition to aerobic CH₄oxidation, which takes place in Lake Matano's oxic mixolimnion, we also detected CH₄oxidation in Lake Matano's anoxic ferruginous waters. Here, CH₄oxidation proceeds in the apparent absence of oxygen (O₂) and instead appears to be coupled to some as yet uncertain combination of nitrate (), nitrite (), iron (Fe) or manganese (Mn), or sulfate () reduction. Throughout the lake, the fraction of CH₄carbon that is assimilated vs. oxidized to carbon dioxide (CO₂) is high (up to 93%), indicating extensive CH₄conversion to biomass and underscoring the importance of CH₄as a carbon and energy source in Lake Matano and potentially other ferruginous or low productivity environments.