Download The Bioaccumulation of Mercury - Phoenix Union High School District

The Bioaccumulation of
Mercury
Cloze reading notes
Mercury is a naturally occurring element found in
the Earth’s crust
Mercury is commonly used in thermometers and
compact fluorescent light bulbs
Mercury is also present in coal and when coal is burned it is
released into the air. This is the largest source of anthropogenic
mercury in the environment in the US. Other sources are
manufacturing and industry. A natural release of mercury is from
volcanoes.
Mercury from the air settles in water or onto land where it
can be washed into water. It is then transformed into
methylmercury by certain organisms. This form is highly
toxic and builds up in shellfish and fish.
Methylmercury is a neurotoxin, meaning
it effects the brain. In children
methylmercury impairs neurological
development and impacts cognitive
thinking ability, memory, attention,
language, fine motor skills, and visual
spatial skills. It can slow neurological
processes in adults
Methylmercury is taken up by tiny aquatic plants called
phytoplankton and tiny animals called zooplankton. These
organisms are eaten by larger organisms such as fish, and
the concentration of methylmercury increases at each level
of the food chain. The larger and older the fish the more
accumulation of mercury in their system.
The process of taking in the contaminant,
such as methylmercury and storing it in the
body is called bioaccumulation. As the
concentrations increase with each level of
the food chain, this process is called
biomagnification. Bioaccumulation occurs
within the organism and biomagnification
occurs within the food chain.