CADMIUM
AND LEAD IN AGRICULTURAL SOIL OF SANTIAGO IXCUINTLA NAYARIT, MEXICO.
Verónica Ibarra, Roberto
Gomez, Rosa M. Arriaga (Dirección de Investigación Científica, Facultad de
Agricultura, Universidad Autónoma de Nayarit, Ciudad de la Cultura Amado Nervo,
Tepic Nayarit, México C.P. 63000 Vibar@nayar.uan.mx).
Two trace elements of great
risk for the environmental health are lead and the cadmium, Kabata 1992, they are in our days
associated to the agricultural products when waters of waste for irrigation
have been used. In state of Nayarit are used for the agricultural irrigation
mainly of bean, rice and tobacco, waters that from the Lerma - Santiago River takes
the residual waters of the Guadalajara, Jalisco.
The bean of the variety
black Jamapa, is one product agricultural of economic importance in this region,
grown sowed 2500 ha, which represent the 95% of the bean grown in the place, is
cultivated under irrigation. The objectives these study are the quantification
of lead and cadmium in the soil, water of irrigation and grain of bean.
30 plots were selected
randomly to quantification of lead an cadmium is carried out with ICP and previous
acid digest carried out, method D4638-86 Of ASTM 1990 for the samples soil, and
bean.
The results showed that the
highest values found for cadmium and
lead in water of irrigation is: 0.0029 and 0.0671 mg . l-1,
respectively and these values were inferior to
the limits established by the Norms Official Mexicans; the highest values of cadmium and lead in soil,
were 0.3069 and 11,440 mg.kg-1 respectively, it was interesting to
note that the two values correspond to
the same plot. In the grain of bean the highest values of cadmium and lead were
0.1106 and 1.54 mg.kg-1
respectively and are minor to the limits established by the World Health
Organization, the cadmium concentration and lead in the grain of bean had a
positive high correlation with the organic matter of the soil.
Kabata, A.P., 1992, Trace
Elements in soil and plants. 2 nd
edition, Sc CRC Press, Printed USA.
ASTM 1990.
INTRODUCTION
Two trace elements of great risk for the environmental health are lead
and the cadmium, they are in our days associated to the agricultural products
when waters of waste for irrigation have been used. Until 1994 in Mexico there
was 6.2 million of ha was crops, under irrigation with 4.11.1010 m3
of coming water from average superficialities that is polluted, this represents
a serious problem of public health for the ease that they have the pollutants
of being absorbed for the several crops. In the coastal Plain of the State of
Nayarit, they are showered 27 000 ha there is mainly of bean, rice and tobacco,
these waters come from the basin hydrologic Lerma – Chapala – Santiago that
takes the residual waters of the city from Guadalajara Jalisco, México mainly.
The zone of study is located
in the municipality of Santiago Ixcuintla Nayarit, in the public land Emiliano
Zapata between 21° 30’ – 22 ° 00’ of north latitude and 105°00’ – 105°30’ of
longitude west to a height of 10 meters above the sea level. The climate is
warm medium humidity AW1 (W) of the classification of modified Koppen by E.
Garcia (1981), the half temperature annual is in the range of 26 – 28 °C, with
half precipitation annual of 1703.12
mm.
The bean is a product economic
importance in the region, in the last ten years, the average of surface grow of
this crops is 2500 ha which represent the 95 % of the bean grow in the region,
a product that is cultivated under irrigation, y the reported consumption is 100g/person/ day, in the state of Nayarit
and 50 g/person/day in México for this importance know if the be using water of
residual origin in this crop could represent a risk for the human health, for
the presence of two element of great risk
how they are lead and cadmium, this study have the quantification of
cadmium and lead in agricultural soil and water of irrigation, and the bean grain of human consumption.
METHODS
SOIL: For the study a simple
random selection of 30 plots with grown of bean variety black jamapa, was
carried out, the samples of soil, were taken from 0 - 30 cm depth later the samples was carried out were dried and
meshed followed the digestion with HNO3 / H2O2 according to the method D4638-86 of
ASTM 1990, the quantification de cadmium an lead with spectroscopy of emission
ICP Mark Spectro Model FMA03, input 220 VAC 60.
WATER: the samples of water
of irrigation were taken the channels that provide of water to the selected
plots, with the methodology of NOM 001-ECOL-1996 the samples were preserved at
pH< 2
according to criteria Standard Methods, Table 1060:1, followed by treatment of
digestion according to the method 3030E
the Standard Methods For the Examination Of Water and Wastewater 1992, which
made with HNO3 concentrated en hot plate until digestion was
completed, after that filtered with paper Wattman 45. The measurements of
cadmium and lead were in Spectroscopy of Emission ICP, according method 3500-Cd
of Standard Methods.
BEAN GRAIN: The bean grain
sampling of the selected plots for the study was carried out, in random manner
at the end of the growing season, 50 pods harvested of each selected plots,
they were put in the plastic bag, for to be analyzed in laboratory, later was
carried out trashing, and drying to 65 °C in stove and digestion treatment
according the method D4638-86 of ASTM 1990, for all samples bidistilled and
deionized we used.
RESULTS AND DISCUSSION.
SOIL: The highest value
found for cadmium in soil was 0.3069 mg.kg-1, and the minimum value
found was 0.1099 mg.kg-1 , the mean value was 0.21 mg.kg-1, the highest value is the plot number 578 in the area study, (in this plot two crop
are established by year in the growing Spring –Summer and Fall Winter), the
minimum value was found at the plot 474 (in which only is established one crop
per year in the growing season, fall – winter and no fertilizer are used). It
is worth to mention the highest value found in the area the study was less to
that cited in the literature for soil type, references are of fluvisol in tree
different countries with an average as follows: Austria 0.37 mg.kg-1,
Grand Britain1.10 mg.kg-1, Poland 0.30 mg.kg-1, Kabata
1992.
The highest found for lead in soil was 11.40 mg.kg-1, and the
minimum 4.36 mg.kg-1, the
mean value was 7.4 mg.kg-1, these values are in according the
literature cited which report common values de 10 – 40 mg.kg-1; Kabata 1992, it is worth to mention that the plot with the highest value of
lead is the same that highest value of cadmium plot number 578.
WATER: for irrigation water
The highest value found for cadmium was 0.0029 mg.lt-1, and the
minimum value found was 0.0013 mg.lt-1, the mean value was 0.0023
mg.lt-1, the highest value was less
that the limited established by NOM-ECOL-001-1996 that is 0.2 mg.lt-1, for water irrigation, The highest value found
for lead was 0.0671 mg.lt-1, and the minimum value found was 0.0285
mg.lt-1, the mean value was 0.0482 mg.lt-1, the highest
value was less that the limited
established by NOM-ECOL-001-1996, that
is 0.5 mg.lt-1, for water irrigation.
BEAN GRAIN: For cadmium the
bean grain had highest value found 0.110 mg.kg-1
The value of the bean grain
is less to the established limited World Health Organization (WHO) 0.50 mg
/person/week if uptake by food Galvao 1987,
considering that consumption per capita
of bean for Mexico is 50 gr/person/day the uptake is 0.0387 mg Cd / person
/week, if we consider the mean value found 0.061 mg.kg-1 uptake is
0.215 mg Cd/person/week and any of the cases is exceeded the limited
established by WHO.
For Lead the bean grain had
highest value found 1.54 mg.kg-1.The value of the bean grain is less
to the established limited WHO 3.00 mg Pb/person
/week if uptake by food, Galvao 1987,
considering that consumption per capita
of bean for Mexico is 50 gr/person/day the uptake is 0.539 mg Pb/ person
/week, if we consider the mean value found 1.3063 mg.kg-1 , uptake is
0.457 mg Pb / person/week and any of the cases is exceeded the limited
established by WHO.
For water irrigation low
correlation in general observed between the variables of soil and of water.
The lead was high positive
correlation with percentage organic matter of soil with the which is in
accordance with that of literature.
Between cadmium and lead of
soil was high positive correlation, with correlation coefficient 0.92 Pr>F
0.0001. Cadmium of bean grain was high positive correlation with percentage of
organic matter of soil with correlation coefficient 0.96 Pr>F
0.0001, about this mention literature that cadmium are found bonded with
organic complexes, which suggest that cadmium was bonded with organic matter
soil. With the rest variables the soil showed very low correlation.
REFERENCES
ASTM, 1990. Printed USA.
Galvao L. Y G.C. 1987,
Cadmio serie vigilancia No. 4 Centro Panamericano de Ecologia Humana y Salud
OPS y OMS Metepec Edo. de Mexico,
Mexico.
Galvao L. Y G.C. 1987, Plomo
serie vigilancia No. 8 Centro Panamericano de Ecologia Humana y Salud OPS y OMS
Metepec Edo. de Mexico, Mexico.
Garcia E., 1981 Modificaciones
al sistema de clasificacion climatica Koppen, Tercera Edici’on, Instituto de
Geografia UNAM, Mexico.
Kabata, A.P., 1992, Trace
Elements in soil and plants. 2 nd
edition, Sc CRC Press, Printed USA.
NOM.ECOL-001-1996, Diario
Oficial de la Federación, México.
Standard Methods For The
Examination Of Water And Wastewater, 1992, Printed USA.