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Table B.1. Irrigation water quality classes to evaluate the risk of its toxic impact on plants in sprinkler
irrigation systems
Water quality parameters
Toxic ions,
in equivalents of Cl
Water quality classes
pH
CO
3
2-
meg/dm
3
Cl
-
, meq/dm
3
from 6,5 to 7,5
0
more than 3,0
less than 15
I
from 5,5 to 6,4
from 7,6 to 8,8
from 0,1 to 0,6
from 3,0 to 15,0
from 15 to 40
II
more than 8,8
more than 5,5
more than 0,6
more than 15
more than 40
III
There is also a system for irrigation water quality assessment related to solonetzization risks,
which is based on the thermodynamic parameters of water and the buffering capacity of soils.
If water quality classes, which are determined from concentrations of alkali metal cations and
thermodynamic parameters, do not coincide, then preference is given to the class determined
form alkali metal cations as a final estimate, because this takes into account more soil properties
including particle-size composition. The phytotoxicity of irrigation waters that are not polluted by
toxic compounds can be assessed on the basis of soil pH, carbonate hardness and the content of
chloride ions.
The other State Standard [7] (developed in cooperation with colleagues from the Institute of
Water Problems and Land Reclamation of the National Academy of Agrarian Sciences) regulates
the ecological safety of all types of irrigation water used in agricultural practices (apart from rice
cultivation) in Ukraine. Regulations set in this Standard are applied to all surface and subterranean
natural waters.
Ecological safety criteria are applied to the assessment of the quality of natural waters used in
irrigation according to sanitation and hygiene as well as environmental pollution regulations. The
results of such assessment serve as a basis for the determination and control of permissible levels
of man- made impacts resulting from irrigation.
Surface and subterranean waters used in irrigation are assessed with the use of parameters that
characterize the following: (i) chemical composition, (ii) environmental safety and phytotoxicity,
(iii) sanitary-toxicological properties of chemical elements and compounds and their abilities to
migrate in water solutions, (iv) bacteriological pollution and (v) concentrations of radioactive
substances (controlled by separate regulations).
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Annex В.Assessing water suitability for irrigation
There are three classes of natural water quality for irrigation purposes: Class I – suitable, Class II
– provisionally suitable and Class III – unsuitable. Class II water can be used along with ecological
impact assessment and the mandatory application of agro-ameliorative measures. Class III water
requires amelioration up to a higher class before it can be used on the land. If the water can be
attributed to different quality classes on the basis of different parameters, then its final grade is
determined by the least favourable parameter value.
The quality control of irrigation water in terms of ecological safety [7, 8] is based on two groups
of parameters:
a) First group – water properties and element concentrations that are essential for soil health.
These parameters are regulated in respect to their influence on the environment;
b) Second group – water properties and element concentrations that have adverse affects on the
state and functioning of agricultural ecosystems and the environment. These parameters are
regulated on the basis of irrigation water quality class.
The first group includes ecological and ecologo-hygienic parameters such as:
• the content of nitrogen;
• the content of micro-nutrients (manganese, iron, copper, boron, cobalt, zinc and molybdenum)
and fluorine;
• the biochemical oxygen demand (BOD5).
The second group includes the following parameters:
a) ecotoxicological: (1) concentrations of heavy metals (lead, mercury, cadmium, selenium,
arsenic, total chromium, bismuth, nickel and vanadium) and (2) concentrations of pesticides,
phenols, cyanides, detergents, oil and oil products;
b) sanitary-bacteriological: the presence of (1) Escherichia coli (coli index), (2) Escherichia coli
phages (coli-phage index), (3) pathogenic microflora and (4) viable helminth eggs;
c) radioactive substances.
The classes of natural water quality assessed by concentrations of microelements and heavy metals
are presented in Table B.2.
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