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.