Anthropogenic Sources of Nanoparticles - Nanoparticles' Promises and Risks - page 20

And if the impact of natural particulates has determined the specific adaptation of
living organisms along the time, most anthropogenic nanoparticles were generated
in the nineteenth and twentieth centuries, when large amounts of countless harmful
and change-resistant particulates were released in the atmosphere. Among these are
cancer-causing, mutagenic and teratogenic chlorinated pesticides [ 3 ] that were
largely used in agriculture until recently, heavy metal oxide PM of heavy metals,
PM from the synthesis or chemical purification of various chemical compounds,
fuel combustion or deliberate burning of vegetation for deforestation purposes in
underdeveloped countries.
None of the above-mentioned categories has been the subject of long-term
studies about their impact on health and the environment. The effects of
nanoparticles on the living kingdom have been analysed only recently.
One cannot ignore the unprecedented development of scientific research into
nanoapplications through the synthesis, characterisation and industrial production
of such materials [ 4 - 9 ] which in turn generate various waste types in a similar state
of matter.
Anthropogenic sources of nanoparticles are classified as primary, represented by
ore exploitation, and secondary—PM resulted from industrial activities and energy
production and transport activities.
Secondary sources can be stationary or mobile. The former are thermal power,
chemical, milling, metallurgic or other industrial plants that are continuous and
diffuse and, unlike the latter, produce and release large amounts of PM. The latter
are mostly terrestrial, marine and air vehicle engines and rockets launched to the
extra-atmospheric space. These are considered discontinuous point sources.
As far as global anthropogenic emissions are concerned, the amounts of
nanoparticles released by stationary sources are equal or less than those released
by engines, since the latter total the daily equivalents which account for 40 % of
global pollution [ 10 ].
Table 3.1 is a synthetic presentation of several Australian anthropogenic sources
of nanoparticles [ 11 ].
3.2 Primary Nanoparticle Sources
Depending on the materials extracted from quarries or by underground mining, PM
concentration released during technological processes can have characteristics
similar to those of natural nanoparticle emissions, as it results from the exploitation
of mineral reserves accumulated in time, through orogenesis [ 12 ].
Consequently, the origin of nanoparticles is the direct exploitation of rocks by
surface mining, evacuation through mine shafts or waste heaps produced either
directly, by the separation of the useful fraction, or indirectly, through decantation,
sedimentation or flotation, following the concentration of the useful fraction in ores.
In either case, waste heaps comprise millions of PM which are more or less stable
when rising in the atmosphere.