Geological Carbon Sequestration

A Volatile Organic Compound (VOC) is an organic chemical that has a high vapor pressure at room temperature, leading to significant evaporation. This property is due to a low boiling point. The European Union defines a VOC as any organic compound having an initial boiling point less than or equal to 250°C measured at a standard pressure of 101.3 kPa.

The Ecological Footprint is a resource accounting metric that measures human demand on nature. It quantifies the amount of biologically productive land and sea area required to produce the resources a population consumes (like food, fiber, and timber), and to absorb its waste, especially carbon emissions. It is the 'demand' side of the Earth Overshoot Day (EOD) calculation.

The Kaya identity is a mathematical formula stating that the total emission level of carbon dioxide can be expressed as the product of four factors: human population, GDP per capita, energy intensity (energy per unit of GDP), and carbon intensity (emissions per unit of energy). The formula is \(F = P \times \frac{G}{P} \times \frac{E}{G} \times \frac{F}{E}\), where F is CO2 emissions, P is population, G is GDP, and E is energy consumption.

The Greenhouse Gas (GHG) Protocol categorizes greenhouse gas emissions into three scopes. Scope 1 covers direct emissions from owned or controlled sources. Scope 2 includes indirect emissions from the generation of purchased electricity, steam, heating, and cooling. Scope 3 encompasses all other indirect emissions that occur in a company's value chain, both upstream and downstream, such as purchased goods, business travel, and product use.

Biogenic Volatile Organic Compounds (BVOCs) are VOCs produced and emitted by living organisms, predominantly plants. Isoprene (\(C_5H_8\)) and terpenes are the most abundant BVOCs. While natural, their emissions are vast, exceeding anthropogenic VOCs globally. They play critical roles in plant defense, signaling, and are major precursors for atmospheric ozone and secondary organic aerosols, influencing air quality and climate.

In-Situ Chemical Oxidation (ISCO) is an aggressive remediation technology that involves injecting strong chemical oxidants directly into the contaminated subsurface to destroy pollutants. Common oxidants include permanganate, persulfate, hydrogen peroxide (Fenton's reagent), and ozone. These chemicals react with contaminants, converting them into less toxic substances like carbon dioxide, water, and inorganic salts, without requiring excavation of the contaminated material.

Secondary Organic Aerosols (SOAs) are fine airborne particles formed from the atmospheric oxidation of VOCs. Gaseous VOCs react with oxidants like \(O_3\), \(\bullet OH\), or \(NO_3\bullet\) to produce low-volatility products. These products can then undergo gas-to-particle conversion, either by forming new particles (nucleation) or condensing onto pre-existing aerosols. SOAs are a major component of PM2.5, impacting climate and human health.

Involves capturing CO2 and storing it in the deep ocean, which is the planet's largest carbon sink. Methods include direct injection of liquid CO2 into the water column or onto the deep seafloor, and ocean fertilization to stimulate phytoplankton growth, which absorbs CO2 via photosynthesis. Both approaches have significant environmental concerns, primarily ocean acidification and unpredictable impacts on marine ecosystems.

Biocapacity is a metric that represents the biosphere's regenerative capacity in a given year. It measures the amount of biologically productive land and sea area available to provide resources and absorb wastes under current management practices. It is the 'supply' side of the ecological balance sheet used to calculate Earth Overshoot Day, measured in global hectares (gha).

Earth Overshoot Day (EOD) is the calculated illustrative calendar date on which humanity's demand for ecological resources and services in a given year exceeds what Earth can regenerate in that year. It marks the point where human consumption shifts from using the planet's annual ecological interest to depleting its principal natural capital, effectively living on credit.