Origin anthropogenic

There is also present in the stratosphere a particulate aerosol layer which can, at least temporarily, have an impact on the earth s radiation budget and climate. This layer is formed primarily through oxidation of sulphur-hearing precursor gases of tropospheric origin. Anthropogenic activities contribute to the upward flux of these gases. 

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) ai e toxic compounds of anthropogenous origin, able to accumulate in tissues of alive organisms and to cause different diseases. These compounds ai e the most dangerous for aquatic ecosystems as they easily adsorb in sludge and ai e included in food chains of biota. Humans consume PCBs and OCPs mostly with fish. 

In the marine environment, the numerous radionuclides can be classified into three broad categories based on their production or origin (1) those derived from the weathering of continental rocks, the primordial radionuclides, (2) those formed from cosmic radiation, the cosmogenic radionuclides, and (3) those artificially introduced into nature, the anthropogenic or transient radionuclides and tracers. The primordial radionuclides (e.g. Th, and U) were... 

The majority of published °Pb reports address the utility of °Pb as a geochronological tool rather than as an element that is involved in complex biogeochemical cycles. Nonetheless, some of these studies do provide insight into the geochemical behavior of °Pb and °Po. Nearly all of the lead in the world s surface oceans is believed to be of anthropogenic origin—derived from combustion... 

Certainly, photochemical air pollution is not merely a local problem. Indeed, spread of anthropogenic smog plumes away from urban centers results in regional scale oxidant problems, such as found in the NE United States and many southern States. Ozone production has also been connected with biomass burning in the tropics (79,80,81). Transport of large-scale tropospheric ozone plumes over large distances has been documented from satellite measurements of total atmospheric ozone (82,83,84), originally taken to study stratospheric ozone depletion. 

Apart from CH3 Hg+, other forms of R-Hg+ have been found in the natural environment, which originate from anthropogenic sources but are not known to be generated from inorganic mercury. These forms have been found in terrestrial and aquatic food chains. A major source has been fungicides, in which the R group is phenyl, alkoxy-alkyl, or higher alkyl (ethyl, propyl, etc.). These forms behave in a similar manner... 

CS2 and COS occur in the atmosphere in significant amounts - CS2, 3.8-4.7 Tg S yr-1, COS, 2.7-3.5 Tg S yr-1 one-fifth to one quarter of these amounts are probably anthropogenic. Biogenic CS2 mainly originates in marine settings - anaerobic sediments (bacteria) and salt marshes with a role for Spartina alterniflora.6,10 Some terrestrial plants produce CS2 and tree roots are another source, usually after cutting or wetting. A tree of central America, Stryphnodendron excelsum. can be detected by its CS2 odor.10... 

Several anthropogenic constituents which are present in the atmosphere are potentially useful as an index of water age. Two radioactive gases from nuclear weapons and from power reactors, 3H and 85Kr, have been discussed already. Several other radionuclides of man-made origin are present in the atmosphere and in... 

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