Agriculture Reference
In-Depth Information
Table 7.1 Water quality index based on Class III stipulated by the Peruvian
law for vegetable irrigation and animal consumption
Parameter
Water quality index
High
a
Very high
a
Low
Medium
As (mg/L)
<0.01
0.01-0.02
0.02-0.05
>0.05
Cd (mg/L)
<0.01
0.01-0.05
0.05-0.10
>0.10
Cr hexane (mg/L)
<0.05
0.05-1.00
1.00-2.00
>2.00
Pb (mg/L)
<0.01
0.01-0.05
0.05-0.10
>0.10
Fecal coliforms (MPN/100ml)
<100
100-1000
1000-10,000
>10,000
a
Above permissible limits for vegetable irrigation. MPN, most probable number.
To assess the contamination status of water, the General Water Law of
Peru was consulted (MINAG, 1969, 1976). A water quality index was
designed to provide a simple and concise method for expressing the water
quality of the river. The index was classified in four levels, taking into account
the stipulations for water used for vegetable irrigation and animal
consumption (known as Class III waters) as determined by the Peruvian
General Water Law. Low and medium indexes consider values below the
maximum permissible limits set for Class III, while a high index considers
values two to ten times higher than the maximum permissible set for Class III.
A very high index considers values that are extremely high which are set for
Class III, but which are unsuitable for vegetable irrigation (Table 7.1).
Water quality maps were prepared of each of the water quality parameters
sampled. While they are based on average annual values, and hence do not give
us detailed information about monthly variation, they offer a general idea of
what is influencing their concentrations across the Rı
´
mac River.
Perception of risk of pollution or exposure to contaminants
A detailed survey of 125 of the 276 livestock- and vegetable-producing
households had been previously carried out in the Lurigancho Chosica
district.
3
Survey interviewers asked questions on characteristics of members of
the household, the context of the livestock activity, agronomic management,
livestock management, post-harvest and market activities, water use, excreta
and solid waste disposal, complementary activities, expenditures and family
income, division of labour, and institutional and organizational networks that
are assisted by the activities of UA (Lozano, 2004). We used this survey to
understand what
farmers
think about
their exposure to pollution or
contaminants.
Assessment of water, soil and crop quality in eastern Lima
Lurigancho Chosica is one of the most important farming areas, supplying as
much as 35 per cent of the vegetable market in Lima. It is located in the lower
