carbon dioxide produced by respiration
processes (in both plants [dark cycle] and
animals) will lower the pH of the water. The
carbon dioxide and bicarbonate removed from
the water by the photosynthetic processes of
aquatic plants raises the pH and concurrently the
same processes alter the dissolved oxygen
content. A pH that is too high is undesirable
since the concentration of free ammonia
increases with rising pH.Phosphates
(PO 4 3–)
Phosphates are an essential nutrient for aquatic
plants, but only in very low concentrations.
Excessive amounts of phosphorous build up
easily, and small amounts can contaminate large
volumes of water, resulting in increased algae
growth, which blocks sunlight, decreases DO,
and increases decomposition rates. Sources
include fertilizers, sewage, and detergents.
Phosphorous exists in water in both organic and
inorganic forms.Salinity Chloride (Cl–) is one of the major ions found in
water and sewage. Its presence in large amounts
may be due to natural processes, such as the
passage of water through natural salt formations
in the earth, or it may be an indicator of pollution
from seawater intrusion or industrial or domestic
waste from de-icing processes. Proper salinity
levels are required to maintain osmotic pressure
for living cells. Decreased salinity also results in
decreased DO and decreased viability of eggs
and larvae. An increased Cl– concentration
interferes with hatching, embryo development,
and reproduction.Solids A steady concentration of dissolved minerals is
necessary to maintain the osmotic balance with
the cells of organisms. Changes in concentration
can lead to a weakening of the organism or even