Biogeochemical Equation of State for the Sea-Air Interface

Abstract

We have recently argued that marine interfacial surface tension must have a distinctive biogeography because it is mediated by fresh surfactant macromolecules released locally through the food web. Here we begin the process of quantification for associated climate flux implications. A low dimensionality (planar) equation of state is invoked at the global scale as our main analysis tool. For the reader’s convenience, fundamental surfactant physical chemistry principles are reviewed first, as they pertain to tangential forces that may alter oceanic eddy, ripple, and bubble fields. A model Prandtl (neutral) wind stress regime is defined for demonstration purposes. It is given the usual dependence on roughness, but then in turn on the tension reduction quantity known as surface pressure. This captures the main net influences of biology and detrital organics on global microlayer physics. Based on well-established surrogate species, tangent pressures are related to distributed ecodynamics as reflected by the current marine systems science knowledge base. Reductions to momentum and related heat-vapor exchange plus gas and salt transfer are estimated and placed on a coarse biogeographic grid. High primary production situations appear to strongly control all types of transfer, whether seasonally or regionally. Classic chemical oceanographic data on boundary state composition and behaviors are well reproduced, and there is a high degree of consistency with conventional micrometeorological wisdom. But although our initial best guesses are quite revealing, coordinated laboratory and field experiments will be required to confirm the broad hypotheses even partially. We note that if the concepts have large scale validity, they are super-Gaian. Biological control over key planetary climate-transfer modes may be accomplished through just a single rapidly renewed organic monolayer.

Sodium Drives Interfacial Equilibria for Semi-Soluble Phosphoric and Phosphonic Acids of Model Sea Spray Aerosol Surfaces

“…The interfacial microenvironment at the monolayer–water surface has been shown to drive strong binding enhancements, − shift acid–base speciation, − and alter the hydration environment of ions , as compared to the bulk solution equivalent. Monolayer surfaces are often utilized as a model proxy to study the thin organic coating on sea spray aerosols (SSAs), which are emitted from the ocean’s surface. − SSA models thus need inputs from a molecular understanding of the unique surface properties at SSA interfaces and soluble bulk processes. We have chosen to investigate the surface properties of organic phosphorus species at low pH and high ionic strength (with NaCl) to mimic the aging process of SSAs .…”

Modeling Functional Organic Chemistry in Arctic Rivers: An Idealized Siberian System

“…Fresh organic compounds, which were once intracellular, such as lipids and biopolymers, tend to adsorb along the water-air interface with a strong modulation of mass and energy transfer. Heat, momentum and water vapor fluxes are all in play [2]. Macromolecules in the monolayer enter the primary aerosol through bubble bursting [3], and partially oxidized volatile carbon supplies organics to secondary particles, whether in the Arctic regime or globally [4].…”

“…In fact, our work encompasses all macromolecules from soil sources through to open plumes, with the exclusion of structural cellulose and lignin (insoluble to the zeroth order [9,11]). Distinctions between functional distributions from the deep sea to surface ocean and finally freshwater systems are drawn in a section of definitions [2,6,[9][10][11][12]. Then, we proceed through model description/results in this order: the idealized Siberian river is outlined as a low node-number channel map.…”

“…We thus argue that strong biophysical effects should be investigated along the coast. For example, adsorptive proteins may favor the marine-atmospheric interface with slowing to gas or momentum transfer [2], while sugar chains co-adsorb to hydrophilic groups from below [18]. Lipids will contribute to amphiphilicity as well, and organic chromophores extract light passing downward which might otherwise be available to support bioproduction [1].…”

“…All of our dissolved forms are inherently partially oxidized, and furthermore they degrade near the atmosphere to generate precursors to volatile organic compounds (VOCs). Such transitions can actually be driven by photochemistry isolated to the water-air microlayer, at thicknesses as small as a monolayer or a single carbon-carbon bond [2,4]. Example gases include formaldehyde derivatives, as well as glyoxal and low molecular weight acids.…”