3 Causes and Effects of Water Pollution in Romania
65
Table 3.2 Major water pollutants and its contribution to water and biota
Pollutant
category
General
contribution/examples
Relative contribution
Sources
Water
supplies
Biota
Natural
Anthropic
Organic
Add toxics;
Increased
oxygen demand
Plant matter,
livestock
excreta,
pesticides;
solvents
Increased
need of
treatment
Tolerated in
moderate
quantities if is
not released
too quickly,
serious if DO
drops too
quickly
Run-off
and
seepage
through
soil
Domestic
sewage,
food
processing,
animal
wastes,
industry
Immiscible
liquids
Formation of a
layer at the
water surface
that could
prevent
O 2 /CO 2
interchange
Oil
Reduced
dissolved
oxygen;
insect
breeding
affected
Unlikely
Oil-related
activity
Microorganisms Pathogenic to
humans
Cause disease
Bacteria;
viruses;
protozoa;
parasites
Escherichia
coli, total
coliforms,
faecal
coliforms and
enterococci
None
Animal
excrement
Human and
animal
wastes
Endocrine
disruptors
Alteration of
ecology
Drug residues,
hormones and
feed additives
Can be
present in
water sold
in plastic
bottles
May
adversely
affect health
and
reproduction
of both
Fusarium
species of
fungus
Chemical
manufacture,
intensive
farming
Nutrients
Excessive
growth of
plants and other
species
Nitrates and
phosphates
Demand on
dissolved
oxygen
Natural
degradative
processes
Sewages
Animal
wastes,
fertilisers,
detergents
(continued)