چکیده انگلیسی مقاله :
Nanoparticles have no exact definition, but they are
aggregates of atoms bridging the continuum between
small molecular clusters of a few atoms and dimensions
of 0.2–1 nm and chunks of solid containing millions of
atoms and having the properties of macroscopic bulk
material. In water, nanoparticles include colloids; in air,
they include aerosols. Nanoparticles are ubiquitous. We
pay to have them. We pay more to not have them. They
occur as dust in the air, as suspended particles that make
river water slightly murky, in soil, in volcanic ash, in our
bodies, and in technological applications ranging from
ultratough ceramics to microelectronics. They both pollute
our environment and help keep it clean. Microbes
feast on, manufacture, and excrete nanoparticles.
Understanding nanoparticle formation and properties
requires sophisticated physics, chemistry, and materials
science. Tailoring nanomaterials to specific applications
requires both science and Edisonian inventiveness. Applying
them to technology is state-of-the-art engineering.
Tracing their transport and fate in the environment
invokes geology, hydrology, and atmospheric science.
Applying them to improving soil fertility and water retention
links soil science and agriculture to surface chemistry.
Understanding their biological interactions brings in
fields ranging from microbiology to medicine. Probing
the impact of nanoparticles on humans and of human
behavior on the production and control of nanoparticles
requires the behavioral and social sciences, e.g., in dealing
with issues of automotive pollution. The purpose of this
review is to describe some of the unique features of
nanoparticles and to discuss their occurrence and importance
in the natural environment.
Although we often think of the natural environment as
that part of the planet which we can see, a somewhat
broader definition includes the ‘‘critical zone’’: the atmosphere,
hydrosphere, and shallow portion of the solid earth
that exchange matter on a geologically short time scale, on
the order of tens to thousands of years. This critical zone
affects us directly, and our activities influence it. Because
of the active chemical reactions continuously taking place
in the critical zone, and because its temperatures and
pressures are relatively low and it is dominated by water,
solids are constantly being formed and decomposed.
Many of these solids start out as nanoparticles; many remain
so. In a yet broader sense, our entire planet from
crust to core, the solar system, and the galaxy are part of