Anthropogenic contaminants are compounds that derive from human activity related to industry, fossil fuel burning, agriculture, sewage and other waste that affect ecosystems through bioaccumulation and biomagnification. These contaminants are sometimes referred to as contaminants of emerging concern (CEC's) or persistent organic pollutants (POP's). The characteristics of contaminants depend on the chemical composition of the compound, and the residence time of the compound also depends on its chemical composition. These contaminants may have a significant effect on ecosystem dynamics and nutrient cycling based on short and long time scales.
Key questions remain regarding the mobility and persistence of these compounds in the environment. The biogeochemical cycling of anthropogenic contaminants sheds light on distribution and mechanisms that control the fate of these compounds in the natural environment. The emission of anthropogenic contaminants may follow point source or non-point source pollution. Point source pollution typically comes from a single identifiable place, such as manufacturing plants, landfills, industrial infrastructure, and water treatment facilities. Non-point source pollution is typically the result of pollutants released in a wide area, such as runoff products or atmospheric deposition. Anthropogenic contaminants may still be persistent in the environment spite of legal guidelines in manufacturing.
Pollutants of interest Biogeochemical cycling of anthropogenic contaminants occurs through various solid-phase, dissolved, gaseous, and biological forms. The soil solution (sum of dissolved chemical species and soluble chemical complexes) can be thought of as a regulator of contaminant fate.
Pesticides Pesticides are chemical compounds that are used to control, eliminate, or destroy pests in order to protect human food sources and health. Pesticides include compounds known as insecticides, herbicides, fungicides, rodenticides, and algicides. Pesticides are generally categorized based on their chemical composition and mode of action: organochlorines, organophosphates, carbamatess, and pyrethroidss. Most pesticides are considered to be POPs. The Stockholm Convention on POPs identified notable pesticides such as aldrin, chlordane, dieldrin, endrin, heptachlor, hexachlorobenzene (HCB), mirex, toxaphene, dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexane (alpha and beta), chlordecone, dicofol, methoxychlor, pentachlorobenzene, and endosulfan. The major source of pesticides is application in agricultural settings. Notable manufactures of these compounds include BASF, Bayer, DuPont, and Syngenta.Pesticides may undergo complex transformations depending on their chemical composition and physical structure, as well as the environmental conditions like temperature, pH, redox, light availability, organic matter availability, and land-use history. The processes that affect the persistence of pesticides in the environment include photodegradation, chemical degradation, microbial degradation. The processes that impact the mobility of pesticides in the environment include sorption, plant uptake, volatilization from soil, volatilization from foliage, wind erosion, runoff, and leaching. Atmospheric deposition of pesticides occurs through precipitation and spray drift, which results from pesticide not adsorbing to the targeted product indicating a potential error in the application process. Microbial degradation is more likely when pesticides are repeatedly used in the same field.
It is assumed that the residence time of pesticides in soil is indefinite because they degrade slowly in soils. However, it is possible to determine the environmental fate of a specific pesticide knowing the biochemical half-life of the pesticide, soil sorption coefficient, water solubility, vapor pressure, and Groundwater Ubiquity Score. For example, in the absence of colloid-mediated transport, the soil residence time of DDT, chlordane, heptachlor, and dieldrin would range between 20 and 100 years. Pesticides may eventually be transported from the continent to continental shelves into the open ocean. Monitoring data have shown that dicofol is sufficiently persistent to be transported via riverine input to the open sea and to be detected in deep sediment layers dated back several decades. It is possible that different ocean basins act as sources or sinks of the pesticides depending on the air-seawater exchange and continental and riverine fluxes.
PFAS Per- and polyfluoroalkyl substances (PFAS) are a class of human made compounds that generally consist of an alkyl carbon chain with fluorines saturating most carbons and at least one functional group. The presence of the carbon to fluorine bond allows PFAS to be strongly resistance to heat, chemical breakdown and microbial breakdown.EPA. "Per- and Polyfluoroalkyl Substances (PFAS)." EPA, Environmental Protection Agency, 2 Dec. 2025, www.epa.gov/pfas This stability leads to PFAS persisting for decades and upwards of one thousand years in soils and water, which yields the nickname - "forever chemicals". PFAS are most broadly categorized as long-chain or short-chain PFAS. Long-chain PFAS tend to have strong sorption onto organic matter and mineral surfaces, while short-chain PFAS are usually more mobile. The distinction between the long-chain and short-chain PFAS is related to the number of carbon atoms in alkyl chains, fluorine atoms, and functional groups like carboxylic acid and sulfonic acid.Mueller, Robert, and Kate Emma Schlosser. "Naming Conventions for Per- and Polyfluoroalkyl Substances (PFAS) 1." Naming Conventions for Per- and Polyfluoroalkyl Substances (PFAS), Interstate Technology Regulatory Council, Aug. 2020, pfas-1.itrcweb.org/wp-content/uploads/2022/09/NamingConventions_PFAS_Fact-Sheet_083122_508.pdf.
Fluoroplastic compounds were first used during the Manhattan project to separate uranium hexafluoride isotopes. However, PFAS are now used widely in consumer products. There are thousands of different PFAS, but some are more well studied and more widely used. Although some PFAS like perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) have been phased out from commercial products, they have long residence times in the environment because of historical use. Release of PFAS to the environment occurs during the production, use, and disposal of materials containing PFAS from primary manufacturing sites or secondary manufacturing facilities. Major manufacturing and industry sources include building and construction materials; cable and wiring; metal finishing and plating; surfactants and fluoropolymer production; paper products and packaging; semiconductor uses; textiles, leather, and apparel (including carpet and furniture upholstery), among others. Wastewater treatment plants, landfills, and use of Aqueous Film Forming Foam (AFFF) during fire training, fire response, or fire suppression are also considered major sources of PFAS to the environment. Notable manufacturers of PFAS products include 3M and DuPont. General mechanisms of release of PFAS from industrial facilities include wastewater and stormwater discharges, on- and off-site disposal of solid waste, leaching into surface soils and groundwater, accidental release during leaks and spills, and stack and fugitive emissions. Stack emissions may lead to wet or dry atmospheric deposition of PFAS to soil and surface water, which can subsequently result in leaching and groundwater infiltration.
Once the molecule is introduced into the environment, the factors that affect the fate and transport of PFAS are dependent on the chemical characteristics of the PFAS molecule itself (e.g. functional groups, fluorination) and the characteristics of the environment the PFAS is introduced to. One consequence of the inherent chemistry of PFAS is that there may be heterogeneity in PFAS distribution in the environment given that PFAS have both hydrophobic tails and hydrophilic heads. Similarly, these chemicals exhibit a wide range of different rates of degradation in the environment, with different functional groups potentially being further modified in the environment to other types of PFAS. Important environmental conditions like soil mineralogy, organic matter content, pH conditions, oxidation-reduction conditions, precipitation, infiltration rates, groundwater velocities/flow directions, groundwater-surface water interactions, surface water flow rates, atmospheric conditions, and the presence of co-contaminants. It is not uncommon for PFAS to partition between multiple solid phases, such as soils and sediment, organic matter, human waste, sewage, and iron oxides. Therefore, the impact of PFAS on biogeochemical cycles in an environment is site-specific. Due to the chemical composition it is possible for PFAS to bioaccumulate in both terrestrial and marine environments. PFAS may interfere with biogeochemical cycling by altering the soil bacterial and fungal community structures. However, determining how PFAS directly interacts with the major biogeochemical cycles like carbon, nitrogen, oxygen, phosphorus, and sulfur and minor biogeochemical cycles warrants more studies, especially conducted in the field. There is evidence from controlled lab experiments that in some bacterial and archaeal communities exposed to PFAS, there can be a reduction in the abundance of nitrification genes and denitrification genes, leading to a build up of ammonium and a decrease in nitrite and nitrate content. Nitrate and sulfate-reducing bacteria have exhibited metabolic inhibition in the presence of PFAS, which has led to an excess of nitrate and sulfate in soils. Any changes in soil pH and microbial and fungal activity leads to shifts in nutrient availability for plants, which can influence the timing and magnitude of carbon and nitrogen export to the hydrosphere.
Pharmaceuticals and personal care products
Pharmaceuticals and personal care products (PPCPs) include a wide suite of antibiotics, analgesics, steroids, antidepressants, antipyretics, stimulants, antimicrobials, disinfectants, fragrances, cosmetics, and many other chemicals that are widely used on a daily basis for various purposes. Veterinary medicines are also considered PPCPs, although their concentrations tend to be higher near agricultural activity like animal feeding operations. PPCPs may enter the environment by direct discharge into surface water from manufacturing, hospitals, households, wastewater treatment plants, and agricultural runoff. Different continents are different point sources of PPCPs. Due to the widespread use of PPCPs in every day life, environmental inputs are mostly continuous rather than intermittent, which results a persistent background of low level contamination. Nevertheless, there is the potential for seasonality due to climate and recreational activities.