Mass-balance chemistry of ecological compartments: water, soil, sediment, biota, and their interconnecting cycles. Substrate of pollution science and biogeochemistry.
environmental-chemistry
Biogeochemical cycle
Mass-conserving budget of an element through atmospheric, oceanic, lithospheric, and biotic reservoirs with characteristic turnover times τ…
Carbon cycle
Reservoirs (atmosphere ≈ 870 GtC, ocean ≈ 38,000 GtC, soil ≈ 1,500 GtC, biosphere ≈ 550 GtC) connected by photosynthesis/respiration,…
Nitrogen cycle
N₂ (atm ≈78%) fixed into NH₄⁺/NO₃⁻ by bacteria or Haber–Bosch; nitrified, assimilated into biomass, denitrified back to N₂/N₂O. Haber–Bosch…
Water pollution chemistry
Contaminant classes: heavy metals (Pb, Cd, Hg, As), nutrients (N, P) causing eutrophication, persistent organics (PCBs, PFAS), pathogens,…
Soil chemistry
Cation exchange capacity (CEC) on clay/organic-matter surfaces buffers pH and nutrient availability; redox chemistry (Eh–pH diagrams)…
Ocean acidification
Absorption of anthropogenic CO₂ by seawater: CO₂ + H₂O ⇌ H₂CO₃ ⇌ HCO₃⁻ + H⁺; ocean pH has dropped from ≈8.2 to ≈8.1 since pre-industrial,…
Eutrophication
Nutrient (N, P) over-enrichment of surface waters triggers algal blooms whose decomposition depletes dissolved O₂, producing hypoxic 'dead…
Persistent organic pollutants (POPs)
Halogenated, lipophilic organics (PCBs, DDT, dioxins, PFAS) with long half-lives, global transport via 'grasshopper effect', and…
Atmospheric deposition (acid rain)
SO₂ + NOx oxidation to H₂SO₄ + HNO₃ + atmospheric-transport → wet/dry deposition lowers rainfall pH below 5.6. Ecosystem effects:…
Heavy metal bioaccumulation
Hg / Cd / Pb / As biomagnify up food-chain via fat-soluble methylmercury or protein-binding. Minamata Bay 1956 → Minamata Convention 2013…
Pharmaceutical micropollutants
Trace concentrations (ng/L–μg/L) of pharmaceuticals + personal-care-products in surface water from incomplete WWTP removal. Diclofenac,…
Per- and polyfluoroalkyl substances (PFAS)
Long-chain PFAS (PFOS / PFOA) — persistent, bioaccumulative, toxic 'forever chemicals'. Used in firefighting foam, non-stick cookware,…
Acid rain (SOx, NOx)
Likens-Bormann 1972 Hubbard-Brook: SO2 + 1/2 O2 + H2O -> H2SO4; NO2 + OH -> HNO3; pH 4-4.5 in rain since industrial-revolution; Clean Air…
Ozone depletion (Rowland-Molina 1974)
Rowland-Molina 1974 (Nobel 1995): CFCs photolyzed in stratosphere release Cl atoms; Cl + O3 -> ClO + O2 catalytic cycle; Antarctic ozone…
Greenhouse gases + radiative forcing
IPCC 1990+: CO2 + CH4 + N2O + halocarbons absorb IR; radiative-forcing W/m^2 vs preindustrial; CO2 +2.16 W/m^2 (2024); equilibrium climate…
Persistent organic pollutants (POPs)
Stockholm Convention 2001: 12 POPs (PCB + dioxin + furan + DDT + chlordane + ...); bioaccumulation Kow > 5; biomagnification in food-chain;…
Eutrophication (N, P loading)
Vollenweider 1968 P-loading model: phytoplankton bloom triggered when [P] > 25 ug/L; Schindler ELA-227 1974 whole-lake experiments;…
Microplastic pollution (marine)
Thompson 2004 'microplastic' coined; <5 mm fragments in oceans 5.25 trillion pieces (Eriksen 2014); ingestion by zooplankton ->…
Revelle buffer (Revelle 1957)
R Revelle-H Suess 1957 ocean CO2-buffer factor; modern Sabine 2004 anthropogenic-CO2 30% absorbed by ocean.
Rowland-Molina (1974)
F Rowland-M Molina-P Crutzen 1974 (Nobel 1995) CFC-stratospheric-ozone destruction; modern Montreal-Protocol healing 2026+.
Redfield ratio (1934)
A Redfield 1934 C:N:P=106:16:1; modern marine-biogeochemistry + nutrient-limitation + extended Anderson 1995 P-stoichiometry.
Planetary boundaries (Rockström 2009)
J Rockström 2009 + Steffen 2015 9 planetary boundaries; modern 6 transgressed: climate / biosphere / N-P / land / freshwater /…
Paracelsus dose (1564)
Paracelsus 1564 'sola dosis facit venenum'; modern toxicology + dose-response Hill + ecological-risk-assessment frameworks.
Microplastic (Thompson 2004)
R Thompson 2004 'Lost at sea: where is all the plastic?' Science; modern nanoplastic + tire-wear + atmospheric-transport + tea-bag.