Water ecosystem pollution

Risk
Risk –possibility of hazard realization , or expected value of damage due to, for example, pollution of water.
Risk can NOT be measurement by technical methods
in a qualitative sense risk is characterized by adverse consequences nature
in a quantitatively sense risk is characterized by probability of their beginnings

Risk - quantitatively
in a quantitatively sense risk can be shown:
P, Pi – probability of adverse consequences Z, Zi , that can be put into money (sum damage) or publik permissible risk without money dimension.
As a publik permissible risk can be used MPL (maximum permissible load) of different toxic substances

Risk factor
Risk factor – has dimension and can be show by:
Risk=Exposition * Toxic
Exposition – volume of contaminant for one biological target
Risk management - decision about contaminant using or putting a veto upon it, limitation its production, preparation of special corresponding documentation

Risk factor
Pw – characteristic of hydrolyze volume (speed) (Pw=1 – for quick type an Pw=2 – for slow)
BA – bioaccumulation factor, corresponds to contaminant bioconcentration Bcf in a hydrobiont
Cf – contaminant concentration in hydrobiont
Cw – contaminant concentration in water
R – risk factor
E – exposition factor,
from 04 to 25Cw
EFw – factor of effectiveness impact of contaminant
Ew – factor of water exposition
U – method of chemical using (U=5 for “close” - indoors and U=1 for “open”)
BA=2 for Bcf<100;
BA=4 for 100
BA=8 for 1000
BA=16 for Bcf>10000.

Toxic
Toxic – potential risk of contaminant, its possibility to damage.
for toxic estimation there are some standard tests, for lethal (fatal) dose of 50% fish destruction.
In Europe there are 9 tests and three of them - for water:
LC50 – during 96 hours – for fish;
LC50 – during 48 hours – for water flea;
EC50 - inhibition of algea growth
LC50 depend on water conductivity and species diversity
Sum of tests results – EFw.
R →Sy, maxR=1, minR=0 (Isidorov, 1997).
LC50 for:
Cu – 0,02-1,0;
Zn – 0,5-5,0;
Pb – 0,5-10,0;
Cd – 0,5-105,0;
Cr – 3,5-118,0;
Ni – 5.0-100,0;
Fe – 1,4-133,0 mg/l
Conclution about risk by risk factor volume:
Sy≥0,55 – high risk
0,3≤Sy <0,55 - potencial
Sy<0,3 –without risk

Your work
Calculate risk correspond to contaminant “X” in water availability
Calculate risk correspond to contaminant “Y” in water availability
Normalized a risk factor (R) by the equation if risk increases account of “X” increasing
Calculate risk factor for natural water object (LC50 for fish – as was above noticed)